CA1293895C

CA1293895C - Procedure and catheter instrument for treating patients for aorticstenosis

Info

Publication number: CA1293895C
Application number: CA000547258A
Authority: CA
Inventors: Alain Cribier; Brice Letac; John P. Ariola, Jr.
Original assignee: Boston Scientific Corp
Current assignee: Boston Scientific Corp
Priority date: 1986-09-19
Filing date: 1987-09-18
Publication date: 1992-01-07
Anticipated expiration: 2009-01-07
Also published as: US4777951A; JPS6399879A; EP0260711B1; EP0260711A3; EP0260711A2; DE3750718D1; DE3750718T2

Abstract

PROCEDURE AND CATHETER INSTRUMENT FOR
TREATING PATIENTS FOR AORTIC STENOSIS
Abstract Dilatation procedures and catheter instrument for treating patients having acquired aortic stenosis, typically in which there are calcific deposits on the leaflets of the aortic valve. A dilatation balloon introduced into the stenosed aortic valve via the aorta while the blood circulation of the patient is maintained by the heart via the aortic valve, is inflated to grossly deflect the leaflets of the valve in a manner avoiding blocking the outer portions of the commissures of the valve. This inflating step enables substantial flow of blood through the outer portions of the commissures during systole despite the presence in the valve of the large inflated balloon. By prolonging the inflation for at least 30 seconds, over a large multiplicity of heart beats the calcific deposits are disturbed to increase the pliability of the leaflets and the degree of their opening, in an action found not to produce emboli. The catheter instrument incorporates means for measuring the pressure gradient across the valve and has features facilitating introduction, retention of position during inflation, withdrawal and re-crossing of the valve to achieve progressive enlargement of the aortic valve.

Description

CATHETER INSTRUMENT FOR TREATING
PATIENTS FOR AORTIC STENOSIS
Backaround of _he Invention This invention relates to an aortic valve dilatation instrument useful for adult patients having aortic stenosis, especially acquired calcific stenosis, a diseas0 which is prevalent in elderly people.
Stenosis of the aortic valve has long been known to cause serious diminishment of blood flow from the heart. The critical position of the aortic valve, preceding the arteries that nourish the heart and brain as well as all other parts of the body, makes this a very serious ailment.
For those patients sufficiently well to endure the surgery, it has become common to replace the aortic valve wi-th a ~prosthetlc device while the patient is maintained by an extra-corporeal circulation system that by-passes the heart and valve.
There is, however, risk with this major surgical procedure and there remains a large population who are ~too weak or otherwise do not wish to undergo such surgery.
~ Relationship to Prior Techniques Percutaneous transluminal halloon catheter angioplasty is a recogni~ed treatment for peripheral and coronary artery stenosis. This technique has also been used successfully in certain forms oF coarctation of the aorta, pulmonary stenosis, congenital aortic valve stenosis, and mitral stenosis, but not previously in adults with acquired aortic valve stenosis. It might be though~ impossible to diIate such long-standing and a~;

usually calcified lesions because of the anticipated critical effects of the expected disruption of the aortic blood flow in the weakened patient and the apparently serious risk of dislodging particles of the calcific plaque to produce life-threat~?ning emboli in th blood stream, References to work prior to commencement of our development are:

. Cooper, R.S.; Ritter, S.B.; Golinko, R.J.;
~alloon dilatation angioplasty: Nonsurgical management of coarctation of the aorta;
Circulation, 1984; 70:903-07.

Kan, J.S.; White, R.I.; Mitchell, S.E.;
Anderson, J.H.; Gardner, T.J.; Percutaneous transluminal balloon valvuolplasty for pulmonary valve stenosis; C _ ulation, 1984;
69:s54-60.
I

Lababidi, Z.; Wu, J.R.; Percutaneous balloon : pulmonary valvuloplasty; Am J. Cardiol, 1983;
: 20 52:560-62.

Pepine, C:.J.; Gessner, I.H.; Feldman, R.L.;
: : : Percutaneous balloon valvuloplasty for pulmonic valve stenosis in the adult; Am. J. Cardiol, :~ 1982; 50:1442-45.
: :
Rey, C.; Marache,~ P.; Matina, D.; Mouly, A.;
Valvuloplastie transluminale percutanee des stenose6 pulmonaires; A propos de 24 ca~, Arch M ocur, 1985; 78:703-10.

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Rocchini, A.P.; Kveselis, D.A.; Crowley, D., Dick Mac, D.; Rosenthal, A.: Percutaneous balloon valvuloplasty for treatment of con~enital pulmonary valvular stenosis in children; J. Am. Coll Cardiol, 1984; 3 l00~-12.
-Lababidi, Z.; Wu, J.R; Walls, J.T.;
Percutaneous balloon aortic valvuloplasty:
results in 23 patients; Am. J. Cardiol, 1984;
53:lg4-97.

Lock, J.E.; Castaneda-Zuniga, W.R.; Fuhrman, B.P.; Bass, J.L.; Balloon dilation angioplasty of hypoplastic and stenotic pulmonary arteries;
Circulation, l983; 67, 5:962-7.

Walls, J.T.; Lababidi, Z.; Curtis, J.J.;
Silver, D.; Assessment of percutaneous balloon pulmonary and aoctic valvuloplasty; J. Thorac.
: Cardiovasc. Surq., I9~4; 88:352-56.

Inoue, K.; Owaki, T.; Nakamura, T.; Kitamura, F.; Miyamoto, N.; Clinical application of transvenous mitral commissurotomy by a new : : balloon catheter; J. Thorac. Cardiovasc. Surq., :1984: 8~:394-~02.

Cohen, M.V.; Gorlin, R.; Modified orifice ~ : equation for the calculation of mitral valve : 25 area; Am. Heart J., 1972; 8~:839.
~ ~ :
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:
:

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Brockmeier, L.B.; Adoph, R.J.; Gustin, B.W.;
Holmese, J.C.; Sacks, J.G.; Calcium emboli to the retinal artery in calcific aortic stenosis;
Am. Heart J/, 1981; 101:32-37.
SummarY of Our Develo~ment In the beginning, percutaneous transluminal balloon catheter aortical valvuloplasty (PTA~) was carried out in three elderly patients with acquired severe calcific aortlc valve stenosis. In all 3 cases, severity of progression made valve replacement appear both mandatory and urgent. We eIected to attempt valvuloplasty, however, because advanced age and poor physical condition made the operative risk very high in 2 patients, while the third refused to contemplate surgery.
Transvalvular systolic pressure gradient was considerably decreased at the end of each procedure, during which there were no complicatlons. Increased valve opening was confirmed by a decrease ln pressure gradient and an increase in valve area calculated by Gorlin's formula using measurement of cardiac output. Subsequent clinical course showed a pronounced functional improvement. (For simplicity, in the following text, measured p~essure gradient will be used to denote the results.) In the course of this work, and con~irmed by many ~; follow-up cases, it has been discovered that placement of an appropriately sized inflated balloon in an aortic valve that is seriously stenosed as a result of calcific plaque build-up, does not, in the majority of cases, significantly worsen blood flow through the stenosed valve during a prolonged treatment (greater ~L~93l~S

than thirty seconds, up -to four minutes); that dilatation and in particular prolonged dilatation provides a very desirable increase in pressure-responsiveness oE the valve leaflets to produce a larger arterial flow; that the calcific plaque, though effectively disturbed by the dil.atation does not result in significant entry of free particles in the vascular system, 50 that life-threatening calcific emboli are not generally formed; and we have confirmed~
by correlation with measured cardiac output, that measurement of pressure gradient across the valve, even with a catheter present in the valve, is useEul as one indication of the imp~ovement achieved by the procedure.
A multipurpose aortic valve dilatation catheter, and procedure using it, has been conceived that significantly reduces the number of procedural steps, reduces the time required for the : procedure, and enhances pa-tient safety. The final design has been ; demonstrated to facilitate re-entry into the valve for repeated dilatation of the aortic valve without need of a guidewire, to : enable monitoring of the results at each step, and to enable ventriculograms, aortograms, and angiograms of the left coronary artery. Use oE the device significantly reduces trauma to the blood vessels, and provides significant improvement in patient comfort.
Certain features are summarized in more detail as fol.lows:
A dilatation procedure for treating patien-ts having calcific aortic stenosis, in which there are calcific deposits on the leaflets of the aortic valve that impair their opening movement dur:ing systole, comprising the steps of: introducing a dilatation balloon into the stenosed aortic valve via the aorta while the blood circulation of the patien~ is maintained by the heart via the aortic valve, inflating the balloon to grossly deflect the calcific leaflets of the valve in a manner avoiding blocking the outer portions of the commissures of the valve, the inflating step enabling substantial blood flow through the outer portions of the commissures during sys~ole despite the presence in the valve of the inflated balloon, and prolonging the inflation of the balloon over an interval spanning a large multiplicity of heart beats, e.g. thirty seconds or longer, whereby the calcific deposits on the leaflets are disturbed to incrQase the pliability of the leaflets and the degrea of their opening in response to systolic pressurQ, the calcific deposits, though thus disturbed by the dilatation, remaining as part of the leaflets so that life-threatening emboli do not orm. In this : 20 manner, while grossly deflected by the balloon, the : : leaflets may be repeatedly, oppositely stressed by exposure to alternating systolic and diastolic pressure conditions to improve their action.
In carrying out the above procedure there are a number of preferred further features: the inflation of the balloon is so performed that, during the inflation, the calculated effective flow cross-section in the unblocked outer portions of the commissures durlng systolQ is o~ the order of or greater than the calculated flow cross-section during systole of the : steno~Qd valve prior to the dilatation; where the treatmQnt i~ o~ a normally sized adult, the balloon is selected to have an aVeraqQ inflat~d diameter in the ranga between about 14 and 24 mm; the interval of prolonged inflation is preferably of the order of one minute or more and preferably no greater than about 5 minutes; the aortic pressure is monitored during the inflation and the inflation is discontinued upon the occurrencQ of substantial decrease in aortic pressure during systole; prior to inflation of the balloon in the valve, the press~re gradient is measured across the aortic valva in the absence o the balloon within the valve, to es~ablish a pre-dilatation base-line value for ~ th~ flow-restriction imposed by the stenosed valve, and during the procedure, following infla~ion of the balloon within the valve, the balloon is withdrawn from the valve, the pressure gradient is re-measured,-and the procedure is terminated when the gradient has substantially decreased, e.g., to about 30 ~m Hg or less; preferably these pressure gradients being measured while a distal portion of the balloon catheter is within the valve; a multilumen dilatation catheter is provided having at least two pressure-measuring lumens in addition to lumen means that inflates the balloon, one of the pressure-measuring lumens terminating in distal sensing port means disposed on the portion of the catheter distal of the balloon, the sensing port means adapted for measuring pressure in the left ventricle of the heart, and a second of the pressure-measuring lumens terminating in a proximal sensing port means disposed :~ along the catheter proximal of the balloon, the second sensing port means adapted for measuring aortic pressure, the distal sensing port means being spaced distally rom tha balloon a distance sufficient that, while the balloon reside~ proximal of the aor~ic valve, ths distal portion of th~ catheter extendinq through the 3~

valve can position the distal sensing port means entirely within the let ventricle of the heart, the procedure includinq the step of positioning the catheter so that the balloon lies proximal of the valve and the distal sensing port means lies entirely within the le~t ventricle, and while the catheter is thus disposed, by use of the distal and proximal sensing port means, measuring the pressure gradient across the valve while the heart is beating, and the procedure including the step of positioning and infiating the '3alloon within the valve to cause the gross deflection of the valve leaflets; a dilatation balloon catheter is provided having a curved distal portion of a stiffness no greater than a first value over a length extending from the distal tip of the catheter to a point close to but distal of the balloon and havin~ a se~ond portion of : substantially greater stiffness extending from the point, proximally at least to a point beyond the portion of the catheter that lies in the aortic arch during inflation of th~ë balloon and preferably for the full length o the catheter to enable the physician to grasp and thrust or twist the catheter without disadvantageous distortion of the catheter, the distal portion adapted to flex and follow a guidewire over which it is threaded to pass through the aortic valve and into the left ventricle, and to conform atraumatically to the wall of the ventricle while the heart is beating, and the second, relatively stiffer portion of the catheter serving to resist collapse under axial compression to enable repeated thrusting of the balloon into the valve, and, by reaction of the catheter against the wall of the aortic arch, to hold the balloon in axial position ~2~3~5 - . 60412-1673 _ g within the valve durlng infla~ion while the ball~on is confronted by pressurized flow o blood from the heart;
during withdrawal the catheter tip is designed to rake across or be manipulated to register with the coronary artery to permit injection of radiopaque contrast fluid.
~ ccording to a further a~pect a method of aortic valvuloplasty, comprises:
A. providing an inflatable balloon cathe~er selected to have an effective balloon si~e and shape to daflect valve leafle~s without ocoluding the outer portions of the commissur~s, the balloon catheter having a relatively ~lexiblQ~ curved distal portion defining a conduit that ha~ a multiplicity o~ side hol~s ~or measUrQment oE pressure and injection of fluid, a relatively stiff distal segment oE catheter substantially smaller than the balloon dispesed between the 1exible curv~d distal portion of catheter and the balloon, and an elonga~ed catheter body proximal of the balloon and defining an opening proximal of the balloon for measurement of pressure;
~ . advancing the balloon catheter until the distal flexible portion is passed through the valve into the ventricle, and the distal stifE segment of catheter i6 lodged within the valve, blood flow through the valve being only minimally impeded because of the relatively small diameter of the stiff segment;
C. measuring the pressurQ in the ventricle by means of the openings in the flexible distal catheter portion and measuri~g the pressur~ in the aorta by means of the proximal opening to de~ermine the pressur~
gradienk across the valve, such gradient being minimally afE~cted by th~ presence of the small diameter, stiff segment of the catheter within the valve:

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D. advancing the catheter until the balloon is positioned within the valve;
E. inflating the balloon to deflect the leaflets of the valve;
F. deflating the balloon and withdrawing the balloon catheter until the stiff segment is again lodged : within the valve;
G. repeating step C to determine the pressure gradient resulting from the treatment; and H. removing the balloon catheter from the patient.
In pr~ferred embodiments, the method includes, after withdrawinq the balloon as provided in step G, thrusting the balloon forward to cause the stif~ seyment to guide the balloon back into the valve, and thereafter repeating steps E, F and G before removing the catheter : from the patient; the method further includes, during the inflation of the balloon, continually monitorinq the ;~ aortic pressure and deflating the balloon and withdrawing it ~rom the valve upon the occurrence of significant drop in aortic pressure, preferably the method further comprises, where desirable, repeating : steps E through G until an acceptable pressure gradient is achieved, and preferably the method further includes continually monitoring aortic pressure and, under the ;~: conditians that the aortic pressure has not : significantly dropped and pressure differential across the valve has remained above about 3~ mm Hg, repeating steps E, F and G; the balloon is of stepped construction of two different diameters, with the smaller diameter : portion positioned distally of the larger diame~er portion, and the method comprises dilating the valve with tile smallar diameter balloon portion and then 3~3~35 11 ~0412-1673 dllating the valve with the larger diameter portion; the method further comprises the step of taking a ventriculogram by inject.ing a radiopaque con-trast fluid through openings of the Elexible dis-tal portion while the distal portion is positloned in the ventricle and the small diameter stlff segment is lodged within the valve; the method comprises withdrawing the distal portion of the catheter through the valve, into the aorta, injecting radiopaque contrast fluid via the distal opening of the catheter into the aorta and performlng an aortogram; the method comprises, during removal of the balloon cathe-ter, positioning the clistal end of the catheter in the left coronary artery osteum and injecting radiopaque con-trast fluid via the distal opening of the catheter into the coronary artery for performing a coronary angiogram; and the catheter is provided with a bend of about 30 proximal of, but adjacent to, the balloon, the method comprising performing initial : diagnostic catheterization of the aortic stenosis using the balloon catheter and a guidewire inserted from the aorta through the valve, over which the balloon ca-theter is passed, the bend facilitating the passage of the catheter over the guidewire, ~0 through the aorta and the valve.
: The invention features aortic valvuloplasty dilatation catheters per se, constructed as described above.
According to the invention there is provided an aortic valvuloplasty dilatation catheter having at least one dilatation balloon and balloon inflation lumen means, said catheter having a curved distal portion of a stiEfness no greater than a first value over a length extending from the distal tip of the catheter to a point close to but di.stal of said balloon and having a second ~3~S

lla 60412-1673 portion of subs-tantially greater stiffness extending from said point, proximally at least beyond the portion of said catheter adapted to lie in the aortic arch during inflation of said balloon, said distal portion adapted to flex and follow a guidewire over which it is threaded to pass through said valve and into the left ventricle, and to conform atraumatically to the wall of said ventricle while the heart is beating, and said second, relatively stiffer portion of said catheter adapted to resist collapse under axial compression to enable repeated thrusting of the balloon into the valve, and, by reaction of the catheter against the wall of the aortic arch, to hold the balloon in axial position within the valve during inflation while the balloon i.s confronted by pressurized oncoming flow of blood from the heart.
Such catheters preferably have a number of further important pre~erred features: the first portion of the catheter incorporates a single lumen adapted to slide over a guidewire and to serve for measurement of ventricular pressure and the second portion of the catheter~incorporates that lumen and at leas~ two - 12 ~

additional lumens, one of which is adapted for measurement of aortic pressure and another of which is adapted for inflation of the balloon; the two portions of the catheter are integral, the first portion of the catheter being the product of heating and radial collapsing of a multiple lumen cathet~r of thermoplastic while only the single lumen is supported by a mandrel residing within the lumen: a stiffener rod is permanently embedded within the catheter, the rod extending distally to the point lying distal of the balloon, preferably the distal tip of the rod being fixQd with respect to the catheter, proximal portions of the rod being free to slide in the lumen relative to the catheter in response for instance to bending of the catheter and/or preferably an extended sleeve integral with the balloon extends distally of the balloon a distanco of between about l and 2 centimeters, serving to stiffen the corresponding portion of the catheter.
In any of the aortic valvuloplasty dilatation catheters above; the balloon preferably has a number of other preferred faatures: it is of stepped construction having at least two different diameters and has tapered transition portions, preferably, in a two diameter balloon the smaller diameter portion of the balloon ~ 25 comprising the distal portion of the balloon beinq : between about 2 and 2.5 cm in longth and having a diameter between about 14 and 18 mm and the larger : diameter portion of the balloon comprising the proximal portion of the balloon bQing between about 3 and 3,5 cm in length and having a diameter between about 18 and 24 mm, the tapered transition portions at the ends of the balloon having a length between about l/2 and l cm and the transition between the two balloon diameters beiny of the order of 1/2 cm in length; a bend in the catheter is providPd of between about 20 and 30, located immediately proximal of the balloon and adapted to ease the passage of the catheter through the aortic arch; the distal portion of the catheter has a compound curvature, the distal-most portion having a smaller radius of curvature than the portion lying proximal thereof, preferably the total arc of curvature is between about 250 and 300; the catheter has a distribution of side holes aIong the length of the distal portion, on the ini3ide of the curve, the proximal-most hole being at least about 3 cms distal of the end of the balloon, for the purpose of left ventricular angiography before the valvuloplasty procedure and supravalvular aortograms;
each hole has a flow cross-sectional area between about 1.5 to 2.0 mm2; there is provided a further hole at the end of the distal portion t~e further hole having a flow cross-sectional area substantially greater than that of any of the side holes; the total arc of the 20 curvature bein~ bet~ween about 200 and 250, the ~: catheter adapted, when the distal tip is withdrawn into t.he aorta from the valve, to register with the inlet of a coronary artery to enable in~ection of radiopaque : contrast fluid therein, whereby an angiogram of the : 25 coronary:artery can be obtained; in one insta,nce, the balloon is cylindricaI and has a diameter betwèen about ~: : 14 and 24 mm and is about 3 l/2 to 4 l/2 cm in length;
in another instance, the balloon is of noncircular cross-sectiQn having a multiplicity of lobes for the : 30 purposa of enhancing blood flow past the balloon; and : : the catheter further comprises a pair of spaced apart radiopague indicators positioned on the catheter, distal of the balloon, to enable the physician to accurately ~ 3~9~i determine the position of the portion of the catheter relative to the valve when the balloon is withdrawn from the valve, wlth one of the markers lying on each side of the valve.
Accordlng to the invention, an aortic catheter comprises a mult.tlumen catheter having at least two pressure-measurlng lumens, one pressure-measurlng lumen termlnclting ln a distal senslng port mean disposed on a distal portlon of the catheter, the sensing port means adapted for measuring pressure ln the left ventricle of the heart, a second pressure-measurlng lumen terminating in a proximal sensing port means disposed proxirnally along said catheter~ the second senslng port means adapted for measurlng aortlc pressure, the dlstal senslng port means being spaced dlstally a distance sufficlent that, while the catheter resides wlthin an aortic val~e, the catheter tlp extends through the valve, for positloning the distal sensing port means entirely within the left ventricle of the heart, whereby when the catheter ls ::

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positioned with the distal sensing port means lying entirely within the left ventricle, by use of the distal and proximal sensing port means, the pressure gradient across the val~e can be measured while the heart is beating.
Other-features and advantages of the invention will be understood from the followin~ description of the original case reports and the presently preferred embodiments, and from the claims.
Initial Case Reports Case 1 A 77 year old woman had been treated for 10 years for angina pectoris. In August, 1984 several syncop~l attacks on mild exertion led to the discovery of aortic stenosis. Angina and exertional dyspnoea severely limited physical activity. Physical examination showed a mid-systolic grade 3J6 murmur at the aortic area, radiating to ~he cervical vessels, an absent second heart sound, and a grade 1i6 dias~olic ; 20 murmur. Electrocardiogram (ECG~ showed pronounced left ventricular hypertrophy, and the left ventricle was moderately enlarged on ~he chest radiograph.
T~o-dimensional t2D~ echocardiogram showed severe aortic stenosis with calcifications and satisfactory left ven~ricular function. In view of the severity of symptoms, cardiac catheterization was proposed ~or preoperative evaluation, but the patient withheld her consent for a ~ear, during which symptoms steadily worsen~d, with nocturnal angina and two episodes of syncope at rest.
Left ventricular catheteri2ation showed left ventricular pressures of 245/28 mm Hg and aortic pressures of 155i70 mm Hg (systolic pressure yradient 90 ~3~5~5 mm Hg). Aortic valve cusps were moderately calcified.
Selective lef~ ven~ricular angiography showed a normal diastolic volume (73 ml/m2), with normal left ventricular function (ejection fraction 775) and clearly thickened walls. Post-stenotic dilatation of the ascending aorta and slight aortic regurgitation were seen on aor~ic angiography. Selective coronary arteriography did not show any significant coronary lesions. The patient gave informed consent for PTAV as an al-~ernative to surgical valve replacement and this was done three weeks later.
Case 2 A 68 year old woman had had aortic stenosis diagnosed 15 years previously. Her clinical status deteriorated progressively over the years (New York Heart Association functional class III~ and angina appeared and became progressively worse. Admission for further investigation was precipitated by an attack of severe chest pain when walking against the wind, followed by syncope. Physical examina-tion on admission showed a grade 3t6 systolic murmur at the base, absent second heart sound, and a grade 2/6 diastolic murmur.
There were clearcut signs of left ventricular hypertrophy on ECG and the chest radiograph showed slight cardiomegaly. 2D echocardiogram showed severe calcific aortic stenosis with normal left ventricular function.
Cardiac catheterization demonstrated ventricular pressures of 230/22 mm Hg and aortic pressures of lO0/50 mm Hg (systolic pressure gradient 130 mm Hg~. The aortic valve was massively calcified.
Right heart pressures and cardiac index were normal.
Left ventriculax angiography showed 2 normal 3~5 end-diastolic volume (94 ml/m2) with slightly reduced ejection fraction (54~) and thickened walls. The ascending aorta was moderately dilated, and aortic regurgitation was insignificant. Selective coronary arteriogram was normal.
Severity of both symptoms and haemodynamic data led U5 to propose immediate valve replacement, but the patient would not contemplate surgery. However, she accepted PTAV, which was done a month later.
Case 3 A 79 year old man had complained of p.cogressive exertional dyspnoea for 10 years was admitted ater three syncopal attacks brought on by mild exertion.
Aortic stenosis was diagnosed. Physical examination on admission showed a grade 4/6 mid-systolic murmur at the base, with an absent second heart sound. ECG showed sèvere left ventricular hypertrophy and the chest radiograph mild cardiomegaly and signs of mild pulmonary : hypertension. 2D echocardiogram showed severe aortic stenosis with considerable valve calcification and seve~e left ventricular dilatation with impaired ventricular function. Two days after admission, the patient had an episode of acute, massive pulmOnary oedema which was brought under control with difficulty by high doses of frusemide.
~ At cardiac catheterization, left ventricullar pressure was 140/28 mm Hg (systoiic pressure gradient 60 mm Hg) and the aortic valves were massively calcified.
Left ventricular angiography confirmed left ventricular dysfunction, with an increased diastolic volume (190 ml/m2) and greatly decreased ejection fraction (20~).
SelectivQ coronary arteriography showed major multiple vessel lesions with proximal left-anterior-descending occlusion. These ~indings made us reluctant to re~ommend valve replacement and, with information consent, we decided to attempt PTAV.
Methods The same procedure for PTAV was followed in all 3 patients. Premedication consisted of intravenous atropine sulphate l mg, clorazepate 50 mg, and heparin 100 u/kg bodyweight. A surgical team was on standby.
For continuous aortic pressure monitoring, a 5F
catheter was inserted into the descending thoracic aorta. In addition, a Swan-Ganz thermodilution catheter was inserted into the pulmonary artery in patients 2 and 3 for measurement of cardiac output. Left ventricular catheterization was carried out via the brachial approach which made it easier to cross the stenosed aortic orifice (and was also necessitated by the short length (60 cm) of the dilatation catheters available in our laboratory). A 7F Sones catheter was inserted into the aorta and then in the left ventricle. After simultaneous left ventricular and aortic pressure recording, right-anterior-oblique angiogra~s of the left ventricle and of the aortic root were done. A Cordis straight guidewire, diameter 0.038 inch, length 270 cm, was inserted into the left ventricle via the Sones catheter to enable its replacement by the dilatation catheter.
We used 9F balloon catheters designed for dilatation of congenital valve stenosis, available from Meditech, Incorporated, of Watertown, Massachusetts and from Mansfield Scientific, Inc. of Mansfield, Massachusetts. T~o radiopaque markers gave the positions of the distal and proximal ends of the ~3~ 5 balloon, thus ensuring correct transvalvular positiQning which was also confirmed by narrowing of the balloon where it crossed the stenosis during inflation. The balloons were 40mm long. Inflations were carried out by injecting 10 ml of a 50J50 mixture of saline solution and contrast medium, up to pressures o~ 6-8 atm. Three inflations, lasting 20-60s, were successively done with three balloons whose maximum inflatable diameters were 8, lO, and 12 mm, respectively. In order to stabilize the balloon in its transvalvular position, the guidewire ~ was left in ~ae ventricular cavity during inflation.
ECG and aortic pressure were continuously recorded during the procedure. Ventricular and aortic pressures were simultaneously measured ater each series of inflations, At the end of the procedure, an aortic root angiogram was done to assess valve opening and residual aortic regurgitation.
Results The haemodynamic and clinical response to the inflations was good. There was no loss of consciousness when the balloon was inflated in transvalvular position. The first patient complained of moderate chest pain after 15-20 s of inflation, at the same time an ST-segment depression was noted in the antero-Iateral ; 25 precordial leads. In patients 2 and 3 the three inflat~ions each lasted 1 min. without any ill-effects.
During inflation, the aortic~pressure never ~, ~ decreased below 60 mm Hg. The obstruction caused by the inflated balloon was therefore incomplete; this was confirmed by manual injection of a few ml of contrast medium into the ventricular cavity during one inflation ; (via the angioplasty catheter with guidewire removedi.
A f~w prematUrQ ventricular contractions occurred inrequently during the inflations.

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In ~he first patient, transvalvular gradient was 90 mm Hg at the start of the procedure and remained unchanged after the first two series of inflations with the a and lo mm balloons. After a series of these inflations wi~h the 1~ mm balloon, it decreased to 40 mm H~. In the second patient, the mitral gradient wa~
found to be 80 mm Hg (rather than the 130 mm Hg measured durin~ th~ initial catheterization~ and decreased to 70, 60 and finally 30 mm Hg after each series of inflations. In the third patient, improvement of systolic gradient was very similar - from 60 mm Hg to 50, 40, and finally 30 mm Hg. In patients 2 and 3 in whom cardiac output was measured before and after valvuloplasty, valve surface calculated according to Gorlin's formula increased from 0.46 cm2 to 0.96 cm2 and from 0.50 cm2 to 0.75 cm2, respectively.
Aortic root angiography showed no worsening of the aortic regurgitation. Valve motion, which was considerably impaired before the procedure, wa~s greatly improved, espec'i:ally in the second patient. These results were supported by the f indings of 2D
echocardiography done 24 hours later in the patasternal long axis view, opening of the aortîc valve increased from 0.45 to 0.77 cm in the first case, from 0.41 to 0.72 cm in the second (Fiq. 4); and from 0.32 to 0.48 cm in the third. In the cross-sectional view, valve opening was also clearly improved, mainly in the se~ond patient.
Clinical coursQ during the eight days in hospital after th~ procedure was uneventful in the first two patients, and before discharge both climbed three flight of stairs without any pain or displayed a striking functional improvement. At four weeks, the 12~?~3~395 improvement persisted, there had been little pain, and very little dyspnoca, even thouqh the patients had by then resumed a normal lifestyle. Follow-up of the third patient has been shorter, but it was uneventful ater fifteen days with no more functional signs, including dyspnoca.
Discussion To our knowledge, the 3 patients reported here are the first to undergo PTAV of adult acquired aortic stenosis. Immediate results appear very encouraging, since the cZilatation resulted in a change from severe to moderate aortic stenosis according to the usual haemodynamic criteria--a pronounced decrease in the ventriculo-aortic systolic pressure qradient,-with a residual gradient of 40 mm Hg in one patient, and of 30 mm Hg in the other two.
From the angiographic and echocardiographic data, improvement in the gradient is a consequence of better systolic valve opening. The balloon inflations probably resulted~in a partial tear of the stenosed ;;~ valve~ Although the valve orific~ is often hard to cross in severe adult calcific aortic stenosis, we experienced no technical difficulty in passing the ~ dilatation catheters via the aortic orifice and in reaching a good transvalvular position. The excellent patient tolerance of the inflations is worth emphasi~ing, since we had feared that inflation of the balloon in a stenosed aortic orifice might lead to syncopal circulatory arrest. During the inflations, the aortic pressure remained satisfactory, suggesting that the inflated balloon was not totally occlusive, probably due to the irregular shape of the aortic orifice. There were no complications during or after the procedure, although calcium embolism could be considered a risk.

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These 3 cases, and a large number of further cases using larger balloons and longer durations of inflation illustrate the feasability of the general procedure, its good patient tolerance, and the resulting haemodynamic and clinincal improvement. PTAV can offer a simple therapeutic alternative to patients, mostly elderly, in whom surgery would be to risky or impossible.
Preferred Embodiments _f the Aortic Valvuloplasty Catheter We first briefly describe the drawings.
Drawinqs Fig. 1 is a plan view of an embodiment of the catheter of the invention, Fig. la is an enlargecl view of the distal portion o~ the catheter, and ~ig. lb is an enlarged ViQW of the distal end portion o~ the main catheter body within the balloon; while Figs. 2 and 3 are sec~ion views taken along lines 2-2 and 3-3 of Fig.
1, respectively;
Fig. 4 is a diagrammatic view of the human heart, with the left ventricle shown in section, while Fig. 4a is a schematic, axial view, on an enlarged scale, of the aortic valve as viewed from within the ventricle during the step of the procedure illustrated in Fig. 4;
Figs. 5 through 13 are diagrammatic views of the human heart with the left ventricle, and the aortic valve and arch shown in section, during respective further steps of the procedure, while Fig. 9a is a schematic, axial view, similar to Fig. 4a, as viewed during the step of the procedure illustrated in Fig. 9.
Fig. 14 is a schematic, axial view, on an enlarged scale, simiIar to Figs. 4a and 9a, as viewed during the step of the procedure of Fig. 9 using an alternate embodiment of the catheter of the invention;

Fig. 15 is a partial plan view of the distal portion of the balloon, taken on an enlar~ed scale, of another embodiment of the catheter of the invention, while Figs. lSa, lSb and 15c are cross-sectional views taken on corresponding lines in Fig. 15;
Fig. 16 is an enlarged view of an alterna~e embodiment of the distal end portion of a catheter of the invention, while Fig. 17 is a diagrammatic view of the heart tsimilar to Figs. S through 13) with the catheter distal end portion of Fig. 16 positioned in the left main coronary artery osteum; and Fig.18 is a side view of a diagnostic catheter of the invention.
The aortic valvuloplasty dilatation catheter instrument 10 comprises a 9 French catheter of a~out 100 cm length formed over a major portion of its length as a multilumen extrusion of medium density polyethylene material. The catheter has three lumens over its proximal length, Lp. At the proximal end 11 of balloon 22, the main catheter body 8 terminates ~see Fig. lb~ and a single lumen catheter extension 13 of relatively stiff material is joined, e.g., by lap welding, to it. At the distal end of balloon 22, a second single lumen catheter extension 15 of relatively softer material is joined, e.g., by lap welding, to the distal end of catheter extension 13. The largest lumen 14, which has a diameter in the main catheter body of about 1.30 mm and in the catheter extensions has a diameter of about 1.02 mm, is a distal lumen, which runs the entire length of the catheter to distal tip 20, and ~3~il9S

is used for threading the catheter over a guidewire as well as for measuring distal pressure and infusion of fluids. Second lumen 12 is for balloon inflation-deflation and terminates at port 26 in the end surface 28 of main catheter 8 within dilatation balloon 22. The third lumen lS is a proximal pressure measuring lumen that opens at a proximal port 32, about 4 mm long and 0.8 mm wide, situated approximataly 10 cm proximal of the balloon, for measurement of pressure and infusion of fluids. (Tha end of lumen 16 is sealed by plug 30 at surface 28). Lumens 12, 16 have diameter of about 0.8 mm each.
The catheter has an extended curved distal portion of length, Ld, beyond the balloon of about 5 cm length, having six side holes 21, defined on the inside of the curve, each having diameter between about 0.025 to 0.030 inch. The closest hole is placed 3 cms from the balloon and the others are spaced distally therealong at regular intervals. This distal portion of the catheter is of com~ound curvature, a~ shown, with the di.stal-most part Lt having the smallest radius, the total arc of curvature being about 300. The tip is thus shaped so it will rest directed back toward the inside of the curve to avoid contact with the interior wall of the ventricle, and to present a nontraumatic surface to the inner lining of thQ heart. Tha side holes in the distal portion are design~d for measurement of pressure inside the ventricle and also for injection of radiopaque contrast fluid for ventricular graphs at the end o the procedure. The multiple side holes protect against the possibility that one or more holes s may become occluded by rubbing up against the wall of the hear~ and also enable the relative:Ly viscous contrast fluid, when injected, to be dispersed evenly and in desirably large amounts.
The distance from the balloon of the first or most proximal side hole 21 is established to make it possiblQ to deflate the balloon when within the valve, withdraw thQ balloon into the ascending aorta, leaving the most proximal hole 21 still within the ventricle beyond the valve, so that the pressures measured through the di~i:al lumen are the ventricular pressures. These pressures are compared to the pressures measured thruugh the proximal port 32 and lumen 12, these two measurements providing an accurate measuremen-t of pressure gradient across the aortic valve.
Disposed about the catheter are bands 36, 3~, 40 of radiopaque material which give the cardiolo~ist an : accurate radiographic image of the location of the balloon in relation to the aortic valve.
: 20 The distal portion of the cath~ter has an outer diameter of about 7 French and is of relatively softer material. Thus the distal tip is made more ~lexible than the main body of the catheter, and is also made less traumatic to the wall of the ventricle and more able~to easily follow the guidewire. The main body of the catheter is larger in:outer diameter, e.g., about 3.05 mm, compared to the diameter of the distal portion, e.g., about 2.54 mm, and the catheter extension 13 ~ within the balloon is of relatively stiffer material, : 30: giving the main body sufficient axial stiffness to permit the physician to push the balloon repeatedly through the aortic valve and providing a substantial resistance to torque so that the catheter may be twisted :

s to acilitate insertion or to position the tip in a desired place, such as in the coronary artery during withdrawal for injection of contrast media for a coronary radiograph.
In this embodiment, the balloon itself has a thickness of 0.0035 inch and is formed of polyethylene that is biaxially oriented and treated to make it strong and noncompliant, with strength sufficient to withstand in1ation pressures, of the order of 4 to 6 atmospheres, or higher (burst pressure of the order of eight -~- atmospheres). The balloon is approximately 10 cm .n length, a~d tapers gradually from the 9 French catheter shaft at the proximal end and the 7 French tip on the distal end to the full balloon diameter. The-full diameter is different at the two ends of the balloon.
On the distal end 42 there is a smaller balloon section, of 16 mm diameter and at the proximal end 44 there is a larger diameter balloon section of 20 mm diameter. The axial length of the distal portion 42 i9 between about 2 and 2 1/2 cm an~ the length of the proximal portion 44 is betwe~n about 3 and 3 1/2 cm. The tapered transition portions at each end of the balloon have lengths of one half up to one centimeter, and the transition between the two balloon diameters has a lenqth of about one half centimeter.
The balloon terminates distally in a sleeve 43 which makes the corresponding portion of the catheter relatively more stiff than the tip portion to aid in the passage of the balloon when it crosses or re-crosses the valve. The tip portion itself is very flexible and is able to conform to the contours of the ventricle to which it is exposed. The distal sleeve 43 is between 1 and 2 cms in length and has a diameter of about 0.125 ~3~

inch, The proximal sleeve ~5 is curved at an angle between 20 and 30 to provide to the catheter a geometry which eases passage of the device through the aortic arch. The distal sleeve 43 and proximal sleeve 45 are integral continuations of the balloon, and serve to attach the balloon to the cathater itself. The balloon is attached to the catheter by heating the material of the sleeves and the underlying catheter to melt them together.
lo Percutaneous Technique Employing the Seldinger t.echnique for percutaneous insertion, a guidewire 50 is introduced into a puncture in the ~emoral artery of the patient and advanced through the aorta. The guidewire is.advanced and allowed to coil inside the left ventricle (Figs. 4, 4a, 5) The aortic valve dilatation catheter 10 of the inven~ion is advanced along the guidewire, the leading portion of the catheter, conforming to the shape of the guidewir~. The tip 20 is pushed through the aortic valve o~er the guidewire ~Fig. 6). This is followed by the relatively stiff section of the sleeve 43 which helps to dilate the valve (Fig. 7). (The catheter may be preceded in these steps by a diagnostic catheter or ~5 the dilatation catheter 10 itself may be employed for diagnostic purposes.) The guidewire is withdrawn and tha sleeve is positioned within the valve (Fig. 8), as determined by the physician observing the radiopaque rings 33, 40 at either side of valve AV. Also, prior to any portion of -the balloon entsring the valve, i.e., in the position of Fig. 8, but with the guidewire removed, when the holes 21 at the tip o~ the catheter are inside the ventricla and the proximal port 32 of the lumen is ~Z~38~

in the aorta, simultaneous pressures can be taken to enable the physician to obtain a pre-dilatation, base line pressure gradient across the valve by comparing the systolic peaks in the ventricle and aorta. A
ventriculogram is then taken by injection of radiopaque f luid through the distal opening, and also via the side holes, with the physician observing the flow of the radiopaque fluid from the heart. When ready to commence dilatation, the physician, taking advantage of the relatively stiff sleeve lodged in the valve, advances - the deflated balloon between the valve leaflets, VL
tFigs. 9, 9a). During this motion, the tip portion Ld assumes its preset curvQ corresponding to the curved interior wall of the ventricle, the tip portion presentin~ a nontraumatic surace to the ventricle, the reduced diameter and added flexibility of the distal portion and its pre-set curve enabling this to occur with:ease and without traum~ to the ventricle wall.
While aortic pressure is being monitored, the balloon is inflated with liquid:and the valve is dilated : with first the small diameter section of the balloon : 4~. After an interval, the balloon i5 deflated and withdrawn into a position where the tip of the cath~ter, including all the holes 21, remains inside the : 25 ventricle, with the balloon out of the valve, in the aorta, and the stiff sleeve is lying within the valve, Fig. 10.
Pressures are again recorded through the distal and proximal lumens and the pressure gradient across the valve is determined. Depending upon the amount of this ~radient, e.g., if it is abave 30 mm Hg, the balloon is reinserted into the valve, facilitated by the stiff - :29 -sleeve, without need to reinsert the guidswire (Fig.
ll), this time the larger section of the balloon 44 being placed in the valve, and the balloon is again inflated.
Inflation of the balloon may b~e maintained from a few seconds ~o.g., in the case of rapid decrease of aortic pressure) to many minutes, depending upon the condition of the patient, It is found, surprisingly, in a large majority of elderly and gravely ill patients, that despite the stenosed condition of the aortic valve, and the presence of the inflated balloon i~ the valve, the aortic pressure does not rapidly deteriorate~ This i8 attributed to a special condition achieved at the commissures, C, the region o contact between the valve leaflets. It is found that when the inflated balloon is in place, the outer portions CO of the commissures C, open to provide a calculated flow cross sectional area commensurate with or even in some instances greater than the original stenosed calculated flow cross section of ~o the valve.
Longer inflations tend to produce better results. As the heart beats, the valve in response to systolic and diastolic pressure conditions opens and closes around the relatively stiff surface of the highly inflated balloon, which is believed to disturb the calcium deposits in a manner increasing the pliability c,f the leaflets~ Also, when a balloon is first inflated, it has been observed that there are indentations in the balloon in regions where the valve leaflets rQstrain the diameter of the balloon (so called "waisting" of the ballocn). Sometimes a prolonged inflation and/or multiple inflations are required before this waisting action disappears, and the valve leaflets expand.

~3~

It has been found that a cylindrical shape of balloon is helpful in enabling the balloon to be left inflated for an extended period. This is attributed to the fact that a cylindrical balloon shape does not take up the space all the way to the root of the leaflets to block flow while it assures considerable distortion of the leaflets in their root region. This facilitates flow through the outer commissure regions CO held open by the balloon. During treatment, in making the valve leaflets more pliable, it is surmised that the calcium deposits on the leaflets are fractured or disrupted without dislodgement, which enables them to open wider and close more easily in response to the action of the heart, to provide better flow. -During the dilatation procedure, after the large section of the balloon has been expanded and the valve dilated, the balloon is again deflated. The balloosl is again removed from the valve and, with the sleeve within the valve, the pressure gradient again

2~ measured between the aorta and the ventricle, ~ig. 12.If this pressure gradient ha~ decreased sufficiently, e.g., to 30 mm Hg, the procedure is regarded as successfully completed. At this time the physician may perform another ventriculogram hy injecting contrast fluid through the distal lumen of the catheter to exit th~ side holes 21 in the distal portion of the catheter, to observe the wall motion of the ventricle and the level of cardiac function. As the distal tip of the catheter is withdrawn from the valve into the aorta, an aortogram is parformed to confirm that the valve is closing so thQre is no regurgitation into the ventricle 3i~9~

during diastole. The catheter is then removed from the femoral artery, and the artery is compressed until hemostasis occurs and the patient is returned to his room.
Other embodiments of the invention are of course possible. The balloon may have a maximum inflated diameter of up to 24 mm, selected on the basis of the patient's physical characteristics to be less ~han the diameter of the aortic root to avoid stretching of the root, and obstruction of flow and to avcid over-distention of ~he leaflets that could result in regurgitation of flow or evulsion of lea1ets. The balloon may have another shape, e.g., it may be a sausaqe shape of uniform diameter, or be specially shaped to increase blood flow through the commissures during inflation. In certain circumstan~es, e.g., where in addition to the leaflets having calcific plaque, the commissures of an aortic valve are fused, a multilobe balloon, e.g., formed by molding, with 3 or 4 lobes, may be employed to improve blood flow during dilatation ~Fig. 14). The catheter may include a fourth lumen containing a rod, a.g., of metal or plastic, to provide additional stiffness and torqueability of the catheter over its length to the distal end of the balloon, while not afecting the soft tip. The stiffener may be fixed in the lumen, see below, or may be movable to vary the stiffened length of the catheter, and the stifener may be tapered to vary the degree of stiffness provided.
Referring to Figs. 15-lSC in another preferred embodiment, a our lum~n catheter is provided, lumens 12, 14 and 16 serving the functions of the lumen of like numbers in Fig. 1, while lumen 60 is blind, i. Q., it has no outlet at its distal end. A stiffener rod 60 is

3~ 5 permanently inserted in this blind lumen and which is anchored at its distal end relative to the catheter and which is otherwise free to slide relative to the catheter e.g. during bending of the catheter or when subjected to a large change in temperature. This rod provides added stiffness in the region extending distally to the sleeve region beyond the balloon for facilitating crossing and re-crossing of the stenosed aortic valve. It terminates at the end of the sleeve and thus leaves the distal portion of the catheter, LD, with the designed degree of flexibility. A
preferred means of fixing the distal end of the rod within ~he catheter is by the provision of surface roughening at 62 at the distal end, and heating the substance of the catheter, for instance during the affixation of the balloon to cause the plastic to flow into the interstices of the surface roughness, thus to provide a mechanical grip upon the roughened end of the rod.
An altèrnate manufacturing technique involves placing a mandrel in the distal portion of the distal lumen 14 while leaving the other lumens unsupported from within, heating the thermoplastic substance of this portion of the catheter and radially compressing the substanc~ of the catheter to reform it about the mandrel, and cooling. This process closes the smaller lumens 12, 16 and reduces the diameter of the distal lumen 14 to about 1.I2 mm, with the distal opening having a diameter of about 1 mm.
Referring to Fig. 16, the distal tip portion may hava a shape of somewhat less curvature, e.g., about 200, to enable it to be positioned in the left main coronary artery osteum ~Fig. 17). The physician can inject contrast fluid through the distal lumen into the 3~

~12-1673 left coronary artery to observe the coronary artery circulation. Du~ to the relative sizes of the distal and side holes, a sufficient volume of the contras~
fluid flows into the coronary artery t:o allow visualization of the artery.
!

~3~

Also, a catheter device of the invention, formed of a catheter body 100 without an inflatable balloon (Fig, 18~, may be employed for diagnosis in simultaneously measuring the pressure on both sides of the valve for determination of the gradient.

.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An aortic valvuloplasty dilatation catheter comprising a multilumen catheter having a dilatation balloon, balloon inflation lumen means and at least two pressure-measuring lumens, one of said pressure-measuring lumens terminating in a distal sensing port means disposed on the portion of the catheter distal of said balloon, said sensing port means adapted for measuring pressure in the left ventricle of the heart, a second of said pressure-measuring lumens terminating in a proximal sensing port means disposed along said catheter proximally of said balloon, said second sensing port means adapted for measuring aortic pressure, said distal sensing port means being spaced distally from said balloon a distance sufficient that, while said balloon resides proximal of an aortic valve, the catheter tip extends through said valve, for positioning said distal sensing port means entirely within the left ventricle of the heart, whereby when said catheter is positioned so that said balloon lies proximally of said valve while said distal sensing port means lies entirely within the left ventricle, by use of said distal and proximal sensing port means, the pressure gradient across said valve can be measured while the heart is beating, and whereby by relatively little motion from said position said balloon can be positioned within said valve to be inflated to cause gross deflection of the leaflets of said valve.

2. An aortic valvuloplasty dilatation catheter having at least one dilatation balloon and balloon inflation lumen means, said catheter having a curved distal portion of a stiffness no greater than a first value over a length extending from the distal tip of the catheter to a point close to but distal of said balloon and having a second portion of substantially greater stiffness extending from said point, proximally at least beyond the portion of said catheter adapted to lie in the aortic arch during inflation of said balloon, said distal portion adapted to flex and follow a guidewire over which it is threaded to pass through said valve and into the left ventricle, and to conform atraumatically to the wall of said ventricle while the heart is beating, and said second, relatively stiffer portion of said catheter adapted to resist collapse under axial compression to enable repeated thrusting of the balloon into the valve, and, by reaction of the catheter against the wall of the aortic arch, to hold the balloon in axial position within the valve during inflation while the balloon is confronted by pressurized oncoming flow of blood from the heart.

3. The catheter of claim 2 wherein said second portion of greater stiffness extends over substantially the full length of the catheter, to a region within the physician's grasp, said stiffness enabling thrusting and torquing of the catheter without disadvantageous deformation.

4. The aortic valvuloplasty dilatation catheter of claim 2 wherein said first portion of said catheter incorporates a single lumen adapted to slide over a guidewire and to serve for measurement of ventricular pressure and said second portion of said catheter incorporates said lumen and at least two additional lumens, one of which is adapted for measurement of aortic pressure and another of which is adapted for inflation of said balloon.

5. The aortic valvuloplasty dilatation catheter of claim 2 in which said two portions of said catheter are integral, said first portion of said catheter being the product of heating and radial collapsing of a multiple lumen catheter of thermoplastic while only said single lumen is supported by a mandrel residing within said lumen.

6. The aortic valvuloplasty dilatation catheter of claim 2 in which a stiffener rod is permanently embedded within said catheter, said rod extending distally to said point lying distal of said balloon.

7. The aortic valvuloplasty dilatation catheter of claim 6 wherein the distal tip of said rod is fixed with respect to said catheter, proximal portions of said rod being free to slide in said lumen relative to said catheter in response for instance to bending of said catheter.

8. The aortic valvuloplasty dilatation catheter of claim 1 wherein an extended sleeve integral with said balloon extends distally of said balloon a distance between about 1 and 2 centimeters, serving to stiffen the corresponding portion of the catheter, said sleeve having a diameter sufficiently small so as not to impede blood flow through said valve.

9. The aortic valvuloplasty dilatation catheter of any one of the claims 1 to 8 in the alternative wherein said balloon is of stepped construction of two different diameters and having tapered transition portions, the smaller diameter portion of said balloon comprising the distal portion of the balloon being between about 2 and 2.5 cm in length and having a diameter of between about 14 and 18 mm and the larger diameter portion of said balloon comprising the proximal portion of the balloon and being between about 3 and 3.5 cm in length and having a diameter between of about 18 and 24 mm.

10. The catheter of claim 9 wherein said tapered transition portions at the ends of said balloon have a length between about one-half and one cm and the transition between the two balloon diameters having a length of the order of one-half cm.

11. The aortic valvuloplasty dilatation catheter of any one of the claims 1 to 8 in the alternative having a bend of between about 20° and 30° located immediately proximal of said balloon and adapted to ease the passage of the catheter through the aortic arch.

12. The aortic valvuloplasty catheter of any one of the claims 1 to 8 in the alternative having a distal portion of compound curvature, the distal-most portion having a smaller radius of curvature than the portion lying proximal thereof.

13. The catheter of claim 12 wherein the total arc of curvature is between about 250° and 300°.

14. The catheter of claim 12 having a distribution of side holes along the length of the distal portion, on the inside of the curve, the proximal-most hole being at least about 3 cms distal of the end of said balloon, for the purpose of left ventricular angiography before the valvuloplasty procedure and supravalvular aortograms.

15. The catheter of claim 14 wherein each said side hole has a flow cross-sectional area between about 1.5 and 2.0 mm2.

16. The catheter of claim 14 wherein there is provided a further hole at the end of said distal portion, said further hole having a flow cross-sectional area substantially greater than that of any of said side holes.

17. The catheter of claim 12 wherein the total arc of said curvature is between about 200° and 250°, and said catheter is adapted, when the distal tip is withdrawn into the aorta from said valve, to assume a position within the osteum of a coronary artery to enable injection of radiopaque contrast fluid therein, whereby an angiogram of the coronary artery can be obtained.

18. The aortic valvuloplasty dilatation catheter of any one of the claims 1 to 8 in the alternative wherein said balloon is cylindrical and has a diameter between about 14 and 24 mm and is about 3 1/2 to 4 1/2 cm in length.

19. The aortic valvuloplasty dilatation catheter of any one of the claims 1 to 8 in the alternative wherein said balloon is of noncircular cross-section, having a multiplicity of lobes for the purpose of enhancing blood flow past said balloon.

20. The aortic valvuloplasty dilatation catheter of any one of the claims 1 to 8 in the alternative further comprising a pair of spaced-apart radiopaque indicators positioned on the catheter distal of said balloon to enable the physician to accurately determine the position of said portion of said catheter relative to the valve when said balloon is withdrawn from the valve, with one of said markers lying on each side of the valve.

21. An aortic catheter comprising a multilumen catheter having at least two pressure-measuring lumens, one of said pressure-measuring lumens terminating in a distal sensing port means disposed on a distal portion of the catheter, said sensing port means adapted for measuring pressure in the left ventricle of the heart, a second of said pressure-measuring lumens terminating in a proximal sensing port means disposed proximally along said catheter, said second sensing port means adapted for measuring aortic pressure, said distal sensing port means being spaced distally a distance sufficient that, while said catheter resides within an aortic valve, the catheter tip extends through said valve, for positioning said distal sensing port means entirely within the left ventricle of the heart, whereby when said catheter is positioned with said valve while said distal sensing port means lying entirely within the left ventricle, by use of said distal and proximal sensing port means, the pressure gradient across said valve can be measured while the heart is beating.