Aortic valve replacement utilizing the sutureless (Magovern) prosthesis

Aortic valve replacement utilizing the sutureless (Magovern) prosthesis With particular reference to pathologic anatomy and choice of prosthesis C. Walton Lillehei, M.D., Richard C. Lillehei, M.D., Aldo R. Castaneda, M.D. (by invitation), and Randolph M. Ferlic, M.D. (by invitation), Minneapolis, Minn.

I feel my heart new open'd—Shakespeare (King Henry VIII)

Ihe report in 1963 by Magovern-Cromie1 of a successful sutureless aortic ball-valve prosthesis has engendered widespread in­ terest and comment from cardiac surgeons. Those who have favored this type of prosthesis have emphasized the distinct ad­ vantages of speed of insertion, and techni­ cal facility of usage where exposure to the subcoronary root of the aorta may be lim­ ited by the pathologic anatomy. Critics have emphasized the possibilities of régurgitant leaks, dislodgment, and the less favorable ratio of internal to external orifice in the smallest size of the prosthesis. The ease and speed of insertion of the From the Department of Surgery, University of Minnesota Medical Center, and Variety Club Heart Hospital, Minneapolis, Minn. Supported by research grants from Life Insurance Medical Research Fund, U. S. Public Health Service Grants No. HE-00830 and No. HE-7067, Max Baer Cardio­ vascular Research Fund of Fraternal Order of Eagles, and Maria and Joseph Gales Ramsay III Cardio­ vascular Research Fund. Read at the Forty-fifth Annual Meeting of The American Association for Thoracic Surgery, New Orleans, La., March 29-31, 1965.

482

sutureless aortic prosthesis first attracted us to its usage. Experience with the prosthesis and certain anatomical considerations have led to the formulation of some indications and contraindications for its employment. Patient material Our experience is based on an evaluation of 55 patients, 35 males and 20 females. This series includes all patients who were operated upon by the authors at the Uni­ versity of Minnesota Medical Center and Variety Club Heart Hospital between May 22, 1964, and March 1, 1965. Fifty-two of these patients had the Magovern aortic prosthesis inserted, and in 3 patients the Starr-Edwards aortic prosthesis was utilized. Three separate surgical services are repre­ sented, each with its own surgical philos­ ophy and individual variations in surgical technique. It is our belief that this diversity makes these data obtained particularly val­ uable in the evaluation of the usefulness of this prosthesis, since the methods of preoperative evaluation, type of pump oxygenator, and postoperative care were similar. Preoperative status. No patient was asymptomatic and all but 2 of these patients

Volume 50

Sutureless (Magovern) prosthesis

Number 4

483

October, 1965

had exhibited left heart failure previously. Preoperatively, most patients required vigor­ ous adjunctive digitalis and diuretic therapy. Five patients fell into Class II of the American Heart Association functional clas­ sification while the remainder fell into Classes III and IV (Table I). Types of lesions. Cardiac disease and re­ serve were evaluated by left heart catheterization with cardioangiography performed retrogradely through the femoral artery2 or by means of percutaneous cardiac punc­ ture.3 In addition, some patients underwent right heart catheterization when indicated. These studies revealed isolated aortic dis­ ease in 41 cases, of which 23 were aortic stenosis, the remainder, aortic insufficiency (Table II). In those 42 patients in whom the aortic disease was acquired, 7 patients had mitral valves which were so diffusely scarred, re­ tracted, or calcified that they too necessi­ tated replacement. This was done in 6 in­ stances with the Starr-Edwards mitral valve and in 1 case with a Gott2-' mitral prosthesis.

Table I. Functional classification (A.H.A.) of patients undergoing aortic valve replacement with Magovern prosthesis Mortality

Class

No. of patients

Hospital

Late

II HI IV

5 26 21

0 3 (11.5%) 8 (38%)

0 2 2

Totals

52*

11 (21%)

♦Includes 11 patients (with 3 hospital deaths) who had aortic valve replacement plus an additional corrective procedure (see Table I I ) .

In two other instances the mitral disease caused stenosis which was alleviated by concurrent valvuloplasty. Nine patients had congenital aortic valve disease revealed by history and findings both during the catheterization and at op­ eration. Three of these patients had their disease previously complicated by bacterial endocarditis. Two of the patients with con­ genital aortic disease had concomitant con­ genital lesions. One 41-year-old man had a large patent ductus arteriosus which was ligated and divided just prior to going on cardiopulmonary bypass for the placement of the aortic prosthesis. The other case oc­ curred in a 17-year-old boy who was suffer­ ing from a remarkable variety of multiple defects. In addition to aortic valvular in­ sufficiency, he had a discrete subaortic dia­ phragm and diffuse hypertrophie subaortic stenosis with a total systolic gradient of 120 mm. Hg across these two obstructions. In­ fundibular pulmonic stenosis with a systolic gradient 60 mm. Hg and a ventricular septal defect with a 35 per cent left-to-right shunt completed the picture. All of these lesions were diagnosed preoperatively and were suc­ cessfully corrected at the time of opera­ tion. Peri-infarction block. Left ventricular hy­ pertrophy and strain were exhibited in ev­ ery instance. In addition, some patients re­ vealed right ventricular hypertrophy and rhythm abnormalities. Five patients with acquired disease were found to have the electrocardiographic pat­ tern comprising the anterolateral peri-infarc­ tion (myopathie) block. These patients were found to have a left axis deviation of greater

Table II. Aortic valve replacement with sutureless (Magovern-Cromie) prosthesis Lesion Aortic stenosis Aortic insufficiency Double replacement Aortic replacement and mitral valvuloplasty Aortic replacement and other defect Totals

No. of patients 23 18 7 2 2 52

Age range

Mortality

(yr.)

Hospital

Late

38-72 9-65 22-50 39-61 17-40

5 (21.7%) 3 (16.7%) 1 (14%) 1 1

1 3 0 0 0

11 (21%)

Journal of

484

Lillehei et al.

Thoracic and Cardiovascular Surgery

Table III. Aortic valve replacement (May, 1964 - March, 1965) Mortality Type of prostheses Sutureless (Magovern) Starr-Edwards Totals

No. of patients

Age range (yr.)

52* 3t 55

9-72 45-50

Hospital 11 0

Late 4 0

11 (20%)

♦Includes 9 double valve procedures. tAll had cystic medial aortic necrosis with prosthetic graft replacement of the ascending aorta.

than -30 degrees in the frontal plane with an anterolateral myopathie block. The my­ opathie block was identified by the presence of R waves in Leads II and III exceeding 0.04 second in duration, and the area cir­ cumscribed by the S waves in these leads exceeds that of the respective R waves. This sign has been associated with a grave surgical prognosis in our experience and has indicated that the myocardium has sus­ tained severe damage, manifested by de­ creased cardiac reserve and increased irri­ tability. As reported previously, 4 · 5 · 21 these hearts have frequently failed to re-start fol­ lowing cardiopulmonary bypass. Many patients exhibited symptoms and electrocardiographic evidence of myocardial ischemia. Two candidates with aortic dis­ ease died from myocardial infarction a short time preoperatively. The mechanism of their demise is generally unappreciated. Recent studies at this institution revealed that pa­ tients with aortic stenosis had a lower inci­ dence of coronary atherosclerosis and coro­ nary arteriosclerotic occlusion than the com­ parable general population age group. The diminished cardiac output possibly mit­ igates against the arteriosclerotic process. This is paradoxical protection, however, be­ cause the low cardiac output does not sup­ ply the cardiac musculature efficiently and frank muscle infarction without coronary artery occlusion" can and does frequently occur. Surgical procedure The sutureless valve was used preferen­ tially in all but three aortic valve replace­ ments performed during this time (Table III). These 3 patients suffered from cystic

medial necrosis with ascending aortic aneurysms and aortic insufficiency which necessi­ tated prosthetic replacement of the ascend­ ing aorta, in addition to the valvular re­ placement. The friable nature of this tissue, together with the very large annulus, sug­ gested that the valve be sutured in for security and thus a Starr-Edwards aortic valve was utilized. Extracorporeal circulation. All patients were operated upon with the aid of the DeWall-Lillehei bubble type oxygenator7 with the Zuhdi heat exchanger.8 The oxygenator was primed with low molecular weight dextran* plus, usually, 300 to 400 c.c. (for adult sized patients) of 25 per cent mannitol to make a total priming volume of 16 to 20 c.c. per kilogram of body weight. A midline sternotomy was used for the sur­ gical exposure. The presence of prior kidney damage and the development of renal depression during extracorporeal circulation has led to a va­ riety of methods for improving renal func­ tion. The increase in circulating plasma catecholamines with the resultant efferent renal vasoconstriction and decrease in blood flow has led to the pretreatment of patients with phenoxybenzamine.0 This adrenergic blocking agent protects against the previ­ ously observed renal blood flow decrease although the plasma catecholamines are still elevated during cardiopulmonary bypass.10 Moderate systemic hypothermia was used, reducing the rectal temperature to 28° to 30° C , with the esophageal temperature ranging from 23° to 26° C. As the total patient temperature was lowered, the flow *Rheomacrodex, Pharmacia Laboratories, 800 Centennial Avenue, Piscataway, New Market, N. J. 08854.

Volume 50 Number 4 October, 1965

Sutureless (Magovern) prosthesis

485

Fig. 1. Sutureless (Magovern-Cromie) aortic valve prosthesis with Silastic skirt utilized in the majority of the patients herein reported. A, View from above. B, View from below with pins extended. In patients in whom the Silastic skirt might possibly interfere with coronary flow by overlying the coronary orifice, the skirt can be quickly removed. This was done in 2 patients in this series.

rate was also dropped; the flow rates as de­ scribed by Gollan11 were used. While the systemic temperature was fall­ ing to the desired levels, the heart was placed in ventricular fibrillation with a 60 cycle AC current in the range of 2 to 4 volts for the control of air embolism and to ob­ tain a motionless operative field.12 The ascending aorta was then crossclamped and a transverse aortotomy incision was made above the aortic valve. Coronary perfusion. Two of the three sur­ gical services deemed coronary perfusion unnecessary for the placement of the suture­ less valve and thus perfusion was not util­ ized in 15 patients for insertion of the Magovern prosthesis. In the remaining 37 cases, myocardial protection was obtained by utilizing con­ tinuous bilateral coronary perfusion with arterial blood tapped off of the systemic arterial line, except during the actual valve placement, to obviate injuries to the coro­ nary orifices and also in those few instances in which either the right or left coronary artery origin was particularly small. Small separate pumps perfused the right coronary artery at 100 to 125 c.c. per minute, while the left coronary artery was perfused at 125 to 200 c.c. per minute. For perfusion

of the left coronary artery, we have utilized either the Roe cannula with an expansile tip to hold it in place, the Spencer Silastic,* or the self-expanding balloon catheter. For the right coronary artery, the self-expanding bal loon-tipped plastic catheter13 has been the most useful. Additional hypothermie myocardial protection was obtained in some cases with an ice slush of Ringer's solution in the pericardial sac. Technique. Sufficient time should be spent cutting away the heavily calcified or cartilaginous-like valve remnants. A smooth subcoronary orifice is necessary in order to prevent insecure anchorage of the prosthe­ sis, interference with the ball motion, and as a nidus for thrombus formation. Certain additional technical considera­ tions have been adopted during this expe­ rience. The addition of a Silastic skirt on the valve ring (Fig. 1, A and B) and more re­ cently a Dacron skirt (Fig. 2) has insured an immediate blood-tight seal between the prosthesis and the aorticoventricular junc­ tion. We have observed that the firm impaction of the sutureless valve into the ring before advancing the pins allows placement of a valve with a larger outside diameter than would be the case with a sutured valve. *Dow Corning Corp., Midland, Mich.

Journal of

486

Lillehei et al.

Thoracic and Cardiovascular Surgery

In those patients with a very small annulus, another useful step has been the placement of three stay sutures at the commissural junctions for retraction upward during the impaction of the valve (Fig. 3). This ma-

neuver allows considerable pressure to be exerted without danger of aortic tearing. Mitral inspection. Concomitant mitral disease accompanying many of the cases with a rheumatic etiology has led us to in­ spect the mitral valve in every case. By the use of blunt, curved, uterine curettes (Fig. 4 ) , inspection is facilitated through the aortic annulus by retraction on the chordae tendineae and papillary muscles (Fig. 3). This allows the surgeon to obtain full visual­ ization of the mitral valve without an atriot­ omy. Cardiac venting. In most of these patients with isolated aortic valve disease, venting of the right or left ventricle has been omitted. Results

Fig. 2. Sutureless valve with Teflon base and Dacron-covered skirt to promote endothelization.

Mortality. There were 6 deaths that oc­ curred during surgery in these 55 patients, 5 of which resulted from the inability of the heart to resume its pumping load inde­ pendent of cardiopulmonary bypass (see Table I I ) . The other patient had a large elastic annulus in which the prosthesis

Fig. 3. In some patients, particularly those with a small scarred annulus, the placement of 3 commissural sutures will allow effective upward retraction at the time the sutureless valve is inserted thus permitting insertion of a larger prosthesis. The stitches are then removed. The use of a blunt uterine curette (Fig. 4) has been found to facilitate effective inspection of the mitral valve through the transverse aortotomy, thus obviating the need for left atriotomy in cases in which some mitral abnormality may be suspected.

Volume 50 Number 4

Sutureless (Magovern) prosthesis

487

October, 1965

Fig. 4. The blunt uterine curettes found to be very useful for retraction and examination of the mitral valve leaflets through the opened aorta.

proved to be too small and dislodged after completion of the pump run; emer­ gency resuscitation in the operating room was unsuccessful. In four of these instances, after prolonged resuscitative attempts the patient was pro­ nounced dead after the extracorporeal cir­ culation was discontinued. After a short period of time without extracorporeal cir­ culation, the cardiopulmonary bypass was again instituted and the patients were im­ mediately cooled and, with the permission of the relatives, the kidneys were obtained for patients awaiting a renal transplanta­ tion. The uniform, immediate, effective kid­ ney function in all the recipients, described in greater detail elsewhere,21 has been of interest because these donor patients had been on extracorporeal circulation from 6 to 9 hours by the time their kidneys were utilized. This would confirm our previous beliefs14·1S that the oliguric and anuric epi­ sodes occuring postoperatively in some of these patients having open-heart procedures are due to low cardiac output in the ma­ jority of these cases rather than to deleteri­ ous effects attributable to the pump oxygenator perfusion. There were five other hospital deaths. A valve dislodgment occurred in the post-anes­

thetic recovery room. At the unsuccessful re-operation the subcoronary annulus was found to be very elastic, with an ascending aorta of a normal diameter (see Fig. 9 ) . This problem will be discussed more fully below, under valve choice in relation to path­ ologic anatomy. One patient succumbed from myocardial infarction and anuria. Candida albicans septicemia which was sec­ ondary to intensive antibiotic treatment of an Escherichia coli .septicemia was respon­ sible for the demise of another patient. One other patient, 72 years of age, sustained a cerebral vascular accident on the first post­ operative day and succumbed from an ad­ ditional cerebral vascular accident 10 days later in the postoperative period. One un­ usual death in a patient with peri-infarction block occurred 3 weeks after surgery due to the erosion of the ascending aorta by a stainless steel band which had been used to close the sternum. This band had been dislodged at the time of successful external cardiac massage for arrest on the first post­ operative day. Late deaths. Among the 52 patients in whom the sutureless aortic prosthesis was utilized there have been 4 late deaths. The cause of one late death is unknown, whereas another patient, who had had an entirely

Journal of

488

Lillehei et al.

Thoracic and Cardiovascular Surgery

uncomplicated operation, died at home 3 months postoperatively from a yeast infec­ tion (Candida albicans). Two patients suc­ cumbed from valve dislodgment, both 3 months after surgery, and these are dis­ cussed in more detail later, (see Table VI). Postoperative recatheterization. Elective recatheterization and angiography studies have been performed 9 to 12 months post­ operatively on 14 patients with sutureless aortic valves, ranging in size from No. 2 to 7. In 10 patients, both left ventricular and aortic pressures were measured, and none had a systolic gradient (all measurements made at rest). One of these patients had mild aortic régurgitation (1+ to 2+ by an­ giography2) without symptoms or abnormal prosthesis motion so that continued observa­ tion rather than reoperation was advised. Four additional patients had selective aortograms and aortic pressures measured, but for various reasons the left ventricle could not be entered. All 4 of these pa­ tients had normal pulse pressure, and 3 had negative aortograms, with 1 patient show­ ing a trace of aortic régurgitation. These results are superior to those previ­ ously observed20 by us in patients with the Starr-Edwards aortic prosthesis in which 7 of 8 patients had a systolic gradient rang­ ing from 15 to 50 mm. Hg. This finding is of special interest since the sutureless valve has been criticized a priori in this regard. Two factors undoubtedly account for these favorable hemodynamic findings. First, since the sutureless valve is impacted into position, it is possible to place a larger prosthesis than would be possible by means of sutures. Second, we have previously noted20 that the area between the aortic wall and cage is relatively more important than the internal diameter of the prosthesis in determining the resistance to outflow, and it is the patients with this type of anatomy (post-stenotic dilatation) whom we have favored for use of the sutureless valve. Complications Cardiac arrest. Three patients who suffered from cardiac arrest in their post­

operative period were successfully revived with external cardiac massage and DC defibrillation and left the hospital without sequelae. Significant infections with recovery. One patient suffered from subacute bacterial en­ docarditis which gave rise to coronary emboli causing myocardial ischemia and in­ farction. Interestingly, this was detected both by a rise in the heat stable component of lactic dehydrogenase16 and by an in­ creased number of histiocytes in the periph­ eral blood smear.17 Despite multiple nega­ tive blood cultures in this patient, initially, the histiocytes caused persistence in our culture efforts and subacute bacterial endo­ carditis due to Streptococus viridans was confirmed by a later positive blood culture. Successful therapy followed identification of this organism. Two other patients in this series had a gram-negative septicemia, and were suc­ cessfully managed with intensive antibiotic therapy. In another case there was a staphylococci septicemia which responded favor­ ably to therapy. These instances have indi­ cated that it is not necessary to remove the prosthetic device when there is systemic blood stream sepsis, and that this serious complication may be better managed with intensive antibiotic therapy. Heart block. Four patients developed complete heart block during aortic valve replacement with the sutureless valve of which one was permanent. The heart block can be accorded to injury of the main atrioventricular bundle which underlies the junc­ tion between the right and noncoronary cusp. Chronic block occurs probably either as a result of the removal of the calcium which extends into this vulnerable area or results from the extension of the teeth of the valve into the bundle. Temporary block was probably due to hemorrhage or edema in this area. In all instances, myocardial electrodes were immediately placed and con­ nected to an external pacemaker unit as previously described. 18 ' 19 The 3 patients with temporary complete heart block re­ verted to a normal sinus rhythm from 2 to

Volume 50

Sutureless (Magovern) prosthesis

Number 4

4 89

October, 1965

Table IV. Magovern-Cromie aortic prosthesis: postoperative embolization Incidence

No. of patients with prosthesis

Hospital

45

0

After

discharge 2*

*Both were fully anticoagulated. The interval was 3 mo. and 4 mo., respectively, following valve placement.

9 days postoperatively. The 1 surviving pa­ tient with permanent complete heart block was maintained by an external pacemaker and then had a permanent implantable pacemaker inserted 6 weeks after initial surgery.1" Emboli. Of the 3 patients who suffered from cerebral vascular accidents during op­ eration, the 2 survivors had complete func­ tional return to the affected side. Those neurologic signs observable immediately postoperatively were believed due to cal­ cine debris lost into the circulation during removal of their diseased valves. Postoperatively we recommended that all patients be maintained on the coumarin an­ ticoagulants which are started on the third to fourth postoperative day. A survey of all discharged patients and their physicians has revealed only two in­ stances of postoperative embolization (Table IV). The first occurred in a patient 4 months postoperatively who was ade­ quately anticoagulated at the time of em­ bolization. Subsequent recovery from the transient hemiplegia was complete. The other cerebral vascular accident happened in the only patient in this series with post­ operative evidence of some aortic insuf­ ficiency. This patient had a diastolic mur­ mur and an aortogram performed just prior to hospital discharge demonstrated only very small amounts of dye reflux around the posterior portion of this valve. Three months later his physician noted that the diastolic murmur had disappeared. Within that same week the patient suffered a cere­ bral vascular accident the evening after ski­ ing. We theorized that a thrombus had formed on the posterior edge of this valve and that the vigorous exercise had dislodged

it before complete organization could take place. The patient is presently recovering from the effects of this cerebral vascular occlusion. Valve choice in relationship to pathologic anatomy On the basis of the experience obtained with use of the Starr-Edwards and Magov­ ern-Cromie ball-valve prostheses, we are of the opinion that each may have certain particular advantages in relationship to such factors as the pathologic anatomy, associ­ ated severe coronary artery or myocardial disease or multiple valvular involvement. Obviously, there also exists a middle area of overlap in which either type of prosthe­ sis might be utilized to advantage. In Table V we have attempted to formulate some of these considerations upon the basis of our observations. Anatomy favorable to sutureless pros­ thesis. The pathologic alterations associated with calcific aortic stenosis are characteris­ tically a contracted annulus, heavily scarred and calcified, associated with post-stenotic dilatation of the ascending aorta (Fig. 5, A and B). Some of the technical problems of placing a sutured valve into the subcoronary area in such patients have been: lim­ ited exposure, friable tissues for holding Table V. Sutureless aortic valve prosthesis Indications Peri-infarction block electrocardiographic pattern Myocardial infarct electrocardiographic pattern Calcific aortic stenosis Multivalvar replacements (if anatomy favorable) All poor risk patients (if anatomy favorable) Contraindications Cystic medial necrosis Many patients with free aortic insufficiency who have a large, elastic subcoronary annulus Patients with unfavorable anatomy at aortic root (a normal or hypoplastic ascending aorta due to long-standing low output with subcoronary dilatation of the sinuses Val­ sai va)

Journal of

490

Lillehei et al.

Thoracic and Cardiovascular Surgery

Fig. 5. Pathologic anatomy favorable for Magovern prosthesis. A, The retrograde aortogram reveals a severely stenotic calcified aortic valve with a contracted annulus and ascending aortic post-stenotic dilatation. We consider this anatomical configuration to be favorable for a sutureless prosthesis. B, The illustration depicts the sutureless prosthesis seated in the annulus in diastole and systole. Note that there is ample space between the aortic wall and the ball to allow an impeded seating during diastole and ample outflow during systole.

stitches, and, finally, the fact that patients with severe long-standing obstructive lesions have myocardiums less able to withstand operative stress when compared to régurgi­ tant lesions so that operative time has defi­ nitely seemed to be a factor in mortality. In practice we have found that after careful and complete excision of the diseased valve, as outlined above, it is possible to impact securely a sutureless valve with an internal

diameter usually larger than with a sutured prosthesis. Moreover, this can be accom­ plished in less time and with virtually no danger of prosthesis dislodgment or régur­ gitant leakage. Since the post-stenotic dila­ tation gives an inverted cone type of ana­ tomical configuration, one can be assured of ample outflow area around the prosthesis (Fig. 5, B) which is a factor at least as im­ portant as the internal orifice in determin-

Volume 50 Number 4

Sutureless (Magovem)

prosthesis

491

October, 1965

ing cardiac output through a ball-valve pros­ thesis.20 The use of the sutureless prosthesis has significantly reduced our operative risk in the patients with calcific aortic stenosis (see Table VII). Multivalvular lesions. Patients with se­ vere disease in both the aortic and mitral

valves often have a rather limited cardiac reserve, together with significant hepatic, pulmonary, and renal dysfunction, and the shortening of operative time by use of a sutureless aortic replacement together with either a Starr-Edwards or Gott22 type prostheses in the mitral area has appeared to be beneficial (see Table I I ) .

Fig. 6. Unfavorable pathologic anatomy for the sutureless valve. (H. H.. age 22 yr., 4+ aortic insufficiency and mitral insufficiency.) A, The aortogram shows a dilated subcoronary aortic annulus with elastic, uncalcified leaflets resulting in free aortic régurgitation. Note that the ascending aorta is considerably smaller in diameter than the subcoronary annulus due to a long-standing low cardiac output. In this patient at operation a No. 5 Magovern prosthesis fitted securely into the aortic root but the aortic wall protruded between the valve struts to prevent ball closure. B, Portrayal by drawing to illustrate what was observed at operation after bypass was discontinued. During systole the ball moved to the fully opened position, but remained there during diastole, entrapped by the aortic wall, thereby allowing free aortic régurgitation. Further, systolic outflow was seriously interfered with because of the small space between the aortic wall and the ball. C, In this case the patient was severely hypotensive and, as soon as the problem was recognized, the patient was put back on the pump bypass and a sutured valve (9A Starr-Edwards) was substituted.

Journal of

492

Lillehei et al.

Thoracic and Cardiovascular Suraery

Fig. 7. Free aortic régurgitation in a 41-year-old man. Note that the subcoronary annulus is significantly larger than the ascending aorta. At operation, a No. 8 sutureless valve was indicated by the sizer, but it was immediately obvious that a No. 8 valve would occlude the ascending aorta. Therefore, a No. 12 Starr-Edwards sutured valve was utilized.

Anatomical configurations unfavorable to the sutureless aortic prosthesis. Patients with free aortic insufficiency, lack of calci­ fication, and long-standing low cardiac out­ put may present a left ventricular outflow tract as portrayed in Fig. 6, A. This patient also had severe mitral insufficiency which required valve replacement. Note on the aortogram that the ascending aorta is con­ siderably smaller than the subcoronary an­ nulus. At operation the subcoronary an­ nulus was found to be very elastic and a No. 5 sutureless prosthesis was required to fit securely into this area. After the patient came off cardiopulmonary bypass, we found that the valve ball was held in the opened position by the aortic wall which protruded between the valve struts (Fig. 6, B). The solution to this problem was to re­ move the sutureless prosthesis and replace it with a much smaller Starr-Edwards valve (Fig. 6, C). Subsequent to this experience it has been possible to recognize this potential compli­ cation in all cases before closing the aorta. Inspection of the preoperative aortogram also has been very helpful in alerting one to this type of anatomical configura­ tion (Fig. 7) and this awareness will facilitate a correct decision at operation.

Fig. 8. Calcific aortic stenosis. A No. 3 sutureless valve was inserted. Dislodgment occurred in the operating room after termination of cardiopulmo­ nary bypass. It is clear that the annulus in this patient was much too large for the size of the valve utilized.

Valve dislodgment. Dislodgment of a sutureless prosthesis occurred four times in this series (Table VI) and in three of these it is believed that the problem was clearly preventable in light of the experience now available.

Volume 50 Number 4

Sutureless (Magovern) prosthesis

493

October, 1965

In Case 1 (Table VI) the anatomy was favorable and the problem was clearly that of utilizing a valve far too small for the size of the annulus (Fig. 8). In Cases 2 and 3 (Table VI) the use of sutureless prosthesis was inadvisable (Figs. 9 and 10). Both patients had free aortic régurgitation with an elastic subcoronary annulus which was large in relationship to the ascending aorta. If a sutureless prosthesis large enough to be firmly impacted into the subcoronary area is utilized (and even the largest size now available may not be large enough for patient 2, Table VI, Fig. 9) then one runs the risk of ball entrapment by the ascending aorta. On the other hand, use of a smaller sutureless prosthesis in­ vites dislodgment. In such patients, a su­ tured prosthesis is indicated and, fortu­ nately, exposure in such cases is usually ex­ cellent so that the insertion may proceed rapidly and expeditiously.

The fourth patient (Table VI) repre­ sented a technical problem. At the time of operation, removal of very heavy calcifica­ tion probably extending full thickness into the heart and aorta will result in a large subcoronary laceration involving the orifice of the left coronary artery. Considerable time was expended in this repair and also, because the patient preoperatively was con­ sidered to be a very poor risk, we elected to utilize a sutureless valve despite consider­ able concern about the possibility of dis­ lodgment occurring. The immediate recov­ ery was very satisfactory, but sudden dis­ lodgment (confirmed by autopsy) occurred 3 months later. In summary, awareness of some of these variations in the pathologic anatomy of aortic valve disease from preoperative study of angiograms and observations at operation will permit an accurate choice of the type of prosthesis best suited to the patient.

Fig. 9. This aortogram reveals the enlarged, elastic type subcoronary annulus with a "normal" sized aortic diameter. A No. 5 Magovern valve was inserted and dislodged in post-anesthetic recovery room. In retrospect, this type of annulus configuration needs a sutured valve for security because a sutureless valve large enough to fit into the subcoronary annulus securely will likely plug the aortic orifice.

Journal of

494

Lillehei et al.

Thoracic and Cardiovascular Surgery

Fig. 10. Sequential anterior-posterior and lateral (lower) aortogram reveals a partially dis­ lodged valve. Note the differing positions of prosthesis in systole and diastole. This occurred 3 months postoperatively. The patient was taken immediately to the operating room for reoperation but did not survive the emergency procedure (Case 3, Table VI). The observation of a pathologic tilting or rocking motion of the prosthesis at postoperative fluoroscopy (or in angiograms) is an urgent indication for immediate reoperation.

Discussion When comparing the results between su­ tured and sutureless valves for individual lesions it appears that the sutureless valve has significantly reduced the higher mortal­ ity associated with acquired calcific aortic stenosis-" (Table VII) while that for aortic insufficiency has remained relatively un­ changed. Survival statistics in multivalvular proce­ dures have been improved with the Magovern prosthesis (see Table I I ) . Seven pa­ tients had double prosthetic valve replace­

ment with six survivals. Two patients with congenital aortic disease had additional de­ fects repaired along with their aortic valve. Table I serves as a poignant reminder that patients who deteriorate into the termi­ nal stages of their disease face a higher operative mortality. Three of the 5 patients with Magovern valves who had anterolateral myopathie block survived valve replacement (Table VIII). This is in marked contrast to our previous experience in which 18 out of 18 patients with this electrocardiographic pat-

Volume 50

Sutureless (Magovem) prosthesis

Number 4

495

October, 1965

Table VI. Prosthesis dislodgment (sutureless aortic valve) Cases

Age

1

(yr.)

Lesion

Valve

size

Interval

Result

Critique

Died*

Annulus too large

51

Calcific aortic stenosis

In operating room

36

Aortic insufficiency

In post-anes­ thetic room

23

Aortic insufficiency

3 mo.

Died*

Large, elastic annulus

63

Calcific aortic stenosis (periinfarction block)

3 mo.

Died

Subcoronary aortic laceration in­ curred during removal of dis­ eased valve

Died* Large, elastic (Peri-infarc- annulus tion block)

♦Re-operation attempted.

Table VII. Aortic valve replacement (ball valve) Mortality Prosthesis Starr-Edwards 1961-64

Magovern-Cromie 1964-65

No. of patients

Hospital

Aortic stenosis

Lesion

35

13 ( 3 7 % )

Aortic insufficiency

37

7 (19%)

72

20 (27.7%)

Aortic stenosis

25

5 (20%)

Aortic insufficiency

27

6 (22%)

52

11 ( 2 1 % )

Late

Table VIII. Aortic valve disease with electrocardiographic pattern of anterolateral peri-infarction block Mortality Prosthesis

No. of patients

Survived

Starr-Edwards Magovern-Cromie

18 5

0 3 (60%)

tern died in the immediate period following valve replacement with a sutured (StarrEdwards) prosthesis. Summary Thorough removal of the diseased valve, coronary perfusion, and retraction on the commissural junction by means of traction sutures with firm placement of the prosthesis have been the major factors in our technical considerations. The type of pathologic anatomy present in the patient with aortic valve disease is an

In operating 10 1

room

First 24 hr. 5 0

|

Hospital 3 1

important consideration in the choice of a sutured or the sutureless ball-valve pros­ thesis. These anatomical types can be readily identified from the configuration of the aortic valve and ascending aorta in the preoperative aortogram as well as by ob­ servations at operation. The sutureless ball valve has contributed significantly in reducing the mortality of certain patients who require aortic pros­ thesis. This reduction has been most marked in those patients suffering from calcific aortic stenosis with advanced myocardiop-

Journal of

4 9 6 Lillehei et al.

Thoracic and Cardiovascular Surgery

athy as well as in multivalvular procedures. The poor risk patient with a contracted annulus or a patient in need of multivalvular replacement appears to be the most suitable candidate for a sutureless prosthesis. In properly selected patients, the sutureless aortic prosthesis has proved to be a valuable addition to our armamentarium. Sutured valve replacement is indicated in patients with cystic medial necrosis, and in those pa­ tients with an elastic, subcoronary annulus dilated with respect to the ascending aorta. The identification of these particular con­ figurations is very important from the stand­ point of preventing dislodgments. REFERENCES 1 Magovern, G. J., and Cromie, H . W.: Suture­ less Aortic and Mitral Prosthetic Valves, J. THORACIC & CARDIOVAS. SURG. 46: 726, 1963.

2 Sellers, R. D., Levy, M . J., Amplatz, K., and Lillehei, C. W.: Left Retrograde Cardioangiography in Acquired Cardiac Disease: Tech­ nique, Indications and Interpretations. Experi­ ence in 700 Cases, A m . J. Cardiol. 14: 437447, 1964. 3 Levy, M . J., and Lillehei, C. W.: Cardiac Puncture Catheterization. Experience in 80 Patients, Dis. Chest 45: 449, 1964. 4 Eliot, R. S., Sellers, R. D., Lawrence, T . C , Wang, Y., and Lillehei, C. W.: Significant Prognostic Electrocardiographic Finding in Surgery for Aortic Régurgitation, Circulation 30: 73, 1964 (Suppl. III). 5 Eliot, R. S., Sellers, R. D . , and Lillehei, C . W.: T h e Prognostic Significance of Anterolateral Peri-infarction Block in Surgery for Aortic Régurgitation, A m . J. Cardiol. 16: 6771, 1965. 6 Nakib, A . A., Lillehei, C. W., and Edwards, J. E.: Incidence of Coronary Atherosclerosis in Aortic Stenosis and Insufficiency, Arch. Path. In press. 7 DeWall, R. A., Lillehei, C. W., Hodges, P . C , Long, D . M., Wade, J. B., and Cardozo, R. H.: Description of the Helical Reservoir Bubble-Type Oxygenator for Hemodilution Hypothermie Perfusion, Dis. Chest 44: 113, 1963. 8 Zuhdi, N . , McCollough, B., Carey, J., and Greer, A.: Double-Helical Reservoir HeartLung Machine, Arch. Surg. 82: 320, 1961. 9 Lillehei, R . C , Lillehei, C. W., Grismer, J. T., and Levy, M . J.: Extracorporeal Circulation and Myocardial Function: Plasma Catecholamines in Open Heart Surgery; Prevention of Their Pernicious Effects by Pretreatment

With Dibenzyline, S. Forum 14: 269-271, 1963. 10 Indeglia, R. A., Ferlic, R. M., Todd, D . B., Lillehei, R. C , and Lillehei, C. W.: The effect of Phenoxybenzamine (Dibenzyline) on Renal Hemodynamic Changes in Response to Extracorporeal Circulation, J. THORACIC & CARDIOVAS. SURG. I n press.

11 Gollan, F . : Physiology of Cardiac Surgery, Springfield, 111., 1959, Charles C Thomas, Publisher, chapt. 3. 12 Levy, M . I., and Lillehei, C. W.: Apparatus, Application, and Indication for Fibrillatory Cardiac Arrest, Surgery 5 3 : 205, 1963. 13 King, B. J.: A n Improved Coronary Artery Perfusion Cannula, J. THORACIC & CARDIOVAS. SURG. 4 5 : 667, 1963.

14 Doberneck, R. C , Reiser, M. P., and Lillehei, C. W.: Acute Renal Failure Following OpenHeart Surgery Utilizing Extracorporeal Circu­ lation and Total Body Perfusion: Analysis of One Thousand Patients, J. THORACIC & CARDIOVAS. SURG. 4 3 : 441-452,

1962.

15 Grismer, J. T., Levy, M . I., Lillehei, R. C , Indeglia, R., and Lillehei, C W.: Renal Function in Acquired Valvular Heart Disease and the Effects of Extracorporeal Circulation, Surgery 55: 24-41, 1964. 16 Strandjord, P . E., Clayson, K. J., and Freir, E. F . : Heat Stable Lactate Dehydrogenase in the Diagnosis of Myocardial Infarction, J. A . M . A . 182: 1099, 1962. 17 Beeson, P.: Bacterial Endocarditis in Harri­ son's Principles of Internal Medicine, ed. 3, New York, 1958, McGraw-Hill Book Com­ pany, Inc., p . 973. 18 Lillehei, C. W., Levy, M . J., Bonnabeau, R. C , Jr., Long, D . M., and Sellers, R. D.: The Use of a Myocardial Electrode and Pace­ maker in the Management of Acute Post­ operative and Postinfarction Complete Heart Block, Surgery 56: 463-472, 1964. 19 Lillehei, C. W., Sellers, R. D., Bonnabeau, R. C , Jr., and Eliot, R. S.: Chronic Post-Surgical Complete Heart Block, J. THORACIC & CARDIOVAS. SURG. 46: 436, 1963.

20 Lillehei, C. W., Levy, M . J., Lillehei, R. C , Wang, Y., Cruz, A. B., Raster, R. L., and Bonnabeau, R. C , Jr.: Mitral, Aortic, and Tricuspid Valve Replacement With the Ball Valve, Surgery 57: 184, 1965. 21 Lillehei, C. W., Lillehei, R. C , and Ferlic, R. M.: Aortic Valve Replacement Utilizing the Sutureless (Magovern-Cromie) Prosthesis, Am. J. Cardiol. In press. 22 Gott, V . L., Daggett, R. L., Whiffen, J. D., Koepke, D . E., Rowe, G. G., and Young, W. P.: A Hinged-Leaflet Valve for Total Replace­ ment of the H u m a n Aortic Valve, J. THORACIC & CARDIOVAS. SURG. 48: 713-723, 1964.

Volume 50

Sutureless (Magovern) prosthesis 4 9 7

Number 4 October, 1965

Discussion

DR. MICHAEL E. DE BAKEY

Houston,

Texas

I think our experience would generally confirm the observations that have just been made by Dr. Lillehei. I would certainly agree with him on the indications as well as the contraindications. My own personal experience with the use of the Magovern valve is now based on 49 cases, and I would say that as a result of that experi­ ence we would find a definite useful place for this valve. The indications are pretty much those that Dr. Lillehei has brought out. I think it does require a certain amount of experience and a certain amount of practice in fitting the valve properly, and that if the valve does not fit properly, even after trying several times to seat it well, one should not then persist in trying to use it but should simply remove the valve and replace it with the Starr-Edwards valve. The fitting of the valve, I think, is extremely important in insuring its proper seating and its proper fixation. I think this is a technical matter that deserves a certain amount of effort. In the 49 cases I have just referred to, in which we have used this particular valve, our operative mortality has been about the same as it has been with the Starr-Edwards valve, around 12 per cent. There were two late deaths in this series in addition to the six operative deaths, giving a total cumulative mortality, in a little over 1 year in which we have used this valve, of 16 per cent. In none of these cases was death attributable to a defect in the valve. There have been only 3 cases in the series in which there is some evidence of insufficiency, but none of these patients is in serious difficulty and all are much better than they were preoperatively. I may say, therefore, that there were no serious complications or deaths attributable to the use of the valve. I believe this valve has a very useful place and should be added, as Dr. Lillehei said, to our surgical armamentarium in the treatment of these patients. DR. DRYDEN P. MORSE Philadelphia,

Pa.

I would like to compliment Dr. Lillehei on his thoughtful and philosophical paper. I would like to report 1 case which may be the first of many, in which the ball wore out. This patient was operated upon in September, 1963, and 11 months later died suddenly. At autopsy the ball was so small that it could slide in and out through the cage. [Slide] We had to prop up the ball to take this picture because it would fall in and out freely. The ball had worn down from a size 9 Starr

valve to less than a size 8. Its weight was some­ what less than a size 8. [Slide] The factory thought we might have put a size 8 ball in a size 9 cage. However, we use only one valve on the table. We measure the orifice in the patient and then call for the correct size. The other possibility that at the factory the wrong ball was put in is unlikely. We would have noticed it easily slipping in and out of the cage as we inserted it on the table. Also, this patient lived for 11 months before dying suddenly. The final "clincher" was that on measuring this ball's various diameters it was quite irregular in a microscopic way. Its diameter range was 0.007, whereas the usual range for balls coming from the factory may be as small as 0.001, and the worst ball we found coming from the factory had a diameter of only 0.003. This prosthetic failure puts an added burden on the manufacturer to be sure that any new valve, whether sutureless or sutured, and whether of the ball or disc type, has material adequate to withstand the strain. There is also an onus on the surgeon not to use prosthetics when he can use the patient's own tissues. This onus is not as great in the aortic area as it is in the mitral, where I am sure with greater experience and skill a lot more mitral valves of the stenotic type can be made to work again; and some with mitral insufficiency will remain permanently competent with the Nichols type of annulus plication. Such plastic procedures may be preferable to immediate and constant resort to developmental prosthetic devices. DR. CHARLES P. BAILEY New York, N.

Y.

There is probably no one in this audience who admires more the work of Dr. Walton Lillehei, and the papers that he presents are always of the greatest interest and importance. Nevertheless, men are born to differ, and I think it is wrong for the members of this Society to glean the impression that the prosthetic valves have been fully tried and are completely acceptable. Dr. Lillehei said that the plastic procedures upon the aortic and mitral valve in the extensively diseased cases are essentially palliative. I should like to point out that all previous medical experi­ ence and all accepted surgical principles clearly indicate that these prosthetic valves are but palliative by their own nature. They are foreign bodies which will be rejected if the patient lives long enough, and the only question is how long that will take. [Slide] I did not always feel this way, and some of you may have seen this illustration in my textbook which was published in 1955, in which I described a technique of implanting a ball valve suspended by a plastic pedicle by a

Journal of

498

Lillehei et al.

Thoracic and Cardiovascular

Surgery

closed technique. One of those patients lived 11 years and had benefit for at least 8 of those 11 years. That was not the average survival period of the other 35 patients. [Slide] Occasionally we do implant a prosthetic valve. This is a Starr valve, an aortic replacement. There was a special indication here. This particu­ lar patient was a member of the Jehovah's Witness sect and would not let us use any blood transfusions. I didn't think we could perform an extensive plastic repair upon the aortic valve in the time that would be permitted without blood. He is doing quite well 7 months postoperatively. In the words of Adam Wesolowski, "These prosthetic devices have been accepted on the basis of a pitifully short-term follow-up." Last June I asked Dr. Charles Hufnagel, whom I hope is here to confirm this, what the long-term results were in his 300-odd patients submitted to opera­ tion for aortic insufficiency with the use of a true ball valve, implanted within the course of the descending thoracic aorta. He gave figures which indicated that in less than 10 years over 90 per cent of these patients already have died. I know that this valve was not placed in quite the right place. I know it was not as sophisticated as these modern valves, but I have a strong belief that our present valves aren't going to do too much better than that. There are plastic pro­ cedures other than simple commissurotomy, other than simple sculpturing or débridement of the calcium from the valve. The British and the Australians are putting in homologous valves. People in the United States, not only in New York City but even in Seattle, Washington, are building valves out of autog­ enous tissue in a very extensive fashion and sometimes in the form of total replacement. I think we ought to take another look at these procedures because they are not inherently pallia­ tive as is implantation of prosthetic valves. In conclusion I should like to point out that if these procedures should fail eventually and the stenosis or insufficiency should come back years after a tissue valve has been used, the surgeon probably will have a chance to reoperate on the patient. But when a ball valve goes bad (and I should not eliminate the leaflet on meniscus valves), one usually has a chance only to examine the patient on the autopsy table. DR. ALBERT STARR Portland,

Ore.

This was a stimulating and provocative presen­ tation of an important subject—aortic valve replacement. Dr. Lillehei is to be congratulated on his reduction in operative mortality in recent months. I believe it is pertinent to this discussion to review our own operative mortality and provide a progress report on the incidence

of

late death following aortic replacement. [Slide] In 1962 we had three deaths in 16 isolated aortic replacements, an operative mor­ tality of 19 per cent. In 1963 we had 10 deaths in 45 patients, an operative mortality of 22 per cent. In 1964 we had 4 deaths in 61 patients, an operative mortality of 7 per cent. Thus far in 1965 we have had one death in 18 patients, an operative mortality of 6 per cent. This fall in mortality is not related to any significant change in the aortic ball-valve pros­ thesis or in the selection of patients. If any change has occurred in the latter it is on the side of including more severely ill patients in the operative group. Many of our recent patients have been in the 7th and 8th decades of life. The only change in operative technique is the increased percentage of patients operated upon by our resident staff and may be the main improvement. [Slide] Certainly operating time is not a factor in operative mortality as can be seen in our result of multiple valve replacement. Thus, in 1963 we had four deaths in 14 multiple replace­ ments, a mortality of 29 per cent. In 1964 we had two deaths in 27 patients, a mortality of 7 per cent. Thus far in 1965 we have had one death in 14 patients, a mortality of 7 per cent. Included in this group are 13 triple replacements with 11 survivors—all with a suture technique aortic prosthesis. The oldest survivor is 67 years of age. It appears to us that the main problem of valve replacement is not the operative risk which is quite low but the long-term results. [Slide] Thus far, as you can see from our figures, we have not been reaping a harvest of late deaths among patients operated upon early in our experience with aortic valve replacement. Thus in 1962 there were 2 late deaths following aortic replacement in 16 patients; in 1963 there were 4 in 45 patients; in 1964 there were 5 in 61 patients. Thus far in 1965 there have been no late deaths. Thus there were 11 late deaths in 123 surviving patients following isolated aortic valve replacement. This was related to coronary artery disease in 4 patients, coronary embolus in 3 patients, thrombotic occlusion of the prosthesis in 1 patient, erosion of the aortic root in 1 patient, staphylococcal endocarditis in 1 patient, and sudden death without autopsy in 1 additional patient. It is disturbing that late deaths, while they represent less than 10 per cent of the surviving patients, occur at all and it is in this area that we must direct our attention at this stage in the de­ velopment of surgery for acquired valve disease. DR. FRANK C. SPENCER Lexington,

Ky.

I want to propose one hypothesis regarding Dr. Lillehei's delightful presentation. This point is that a comparison of his experiences and ours

Volume 50 Number 4

Sutureless (Magovern) prosthesis 4 9 9

October, 1965

suggests that the most important factor influenc­ ing operative mortality after an adequate aortic valve replacement is the degree of myocardial ischemia incurred with operation. More simply stated: How adequately were the coronary arteries perfused while the valve was inserted? In our series of 32 patients with ball-valve replacements of the Starr type, we employed al­ most continuous coronary perfusion of both coro­ nary arteries. There was not a single instance of low cardiac output afterward. This was obtained by monitoring the left atrial pressure and the pulmonary artery oxygen saturation for 24 hours. The mortality figures are similar to those of Dr. Lillehei and of the patients over 50 years of age. [Slide] This slide illustrates one method of continuous coronary artery perfusion with plastic cannulas inserted into each coronary ostium be­ fore the procedure is started. The perfusion is through separate pumps, perfusing about 200 ml. per minute—usually the heart beats with a sinus rhythm throughout the operative procedure. [Slide] This slide emphasizes one principle— that the cannulas must be pliable if they are to be moved about while the valve is excised and the prosthesis inserted. Otherwise the perfusion must be interrupted or there is grave risk of in­ juring the aortic intima from a rigid cannula. [Slide] Finally, with a complicated aortic re­ construction, continuous perfusion is particularly important. This patient had the Marfan syndrome, requiring aortic valve replacement for aortic in­ sufficiency and an aortic graft for an aneurysm of the ascending aorta. He had 3 hours of con­ tinuous coronary perfusion, and normal cardiac function afterward. DR. FRANK GERBODE San Francisco, Calif.

We don't really have any experience with the Magovern valve. It is probably slightly illegal not to discuss the essence of Dr. Lillehei's paper, but everyone else is taking advantage of the situation by reporting his own experiences, so I would like to report an experience we have had with a Starr-Edwards aortic ball valve. The valve after about 7 or 8 months became grossly incompetent at its attachment to the annulus; in replacing the old valve we were sur­ prised to find that the Silastic ball (as previously described here this afternoon) was not only smaller but was quite irregular and very dis­ colored. It did not actually produce any incom­ petence and it had not got out of the cage, but it was grossly distorted, and physically it had been altered considerably. It is somewhat worri­ some to look at this specimen, as it is apparent that in some circumstances the Silastic ball can become distorted in shape and be subject to wear in a relatively short period of time.

DR. GEORGE J. MAGOVERN

Pittsburgh,

Pa.

I am extremely pleased to have such eminent surgeons as Dr. Lillehei and Dr. De Bakey to confirm our experience with the sutureless tech­ nique of inserting aortic prostheses, and I know there are similar advantages to this technique in the mitral position as well. Our total number of aortic replacements is over 75, with an over-all hospital mortality of 10 per cent. We have never, and I emphasize this point, never had a displace­ ment of the fixation occur. We have been using the cloth cuff modification since September of 1964 and since then have completely eliminated the occasional problem of perivalvular leak. I am pleased to add that 15 patients are now 2 or more years following valve replacement and, although all are on anticoagulants, we have had no late embolie complications or ball dislodgment. While Dr. Lillehei favors the use of this valve in aortic stenosis, we have used it in all types of cases, and, indeed, believe that it func­ tions more easily in aortic insufficiency, particu­ larly if a purse-string suture is used inside the aorta at the base of the leaflets to secure ap­ proximation. However, even this is rarely neces­ sary with the range of valve sizes available now. The valve fixation site should again be stressed, i.e., as shown on the slide, at the base of the aortic leaflets in the aortico-myocardial junction. I would like to add a word about the mitral prosthesis by saying that 23 of our 26 patients operated upon are now living and well. The valve can be very rapidly inserted and it is particularly helpful in those patients with aortic insufficiency, only demonstrable on the pump oxygenator, in that it reduces the time of cross-clamping of the aorta. As shown on this slide, sutureless aortic and mitral prostheses have been simultaneously used with excellent results, particularly in reduc­ ing the bypass time to less than an hour. May I thank the Association for the privilege of the floor and congratulate Dr. Lillehei for this fine paper and Dr. De Bakey, Dr. Kent and others for their valuable suggestions. DR. LILLEHEI (Closing) Thank you very much. I have enjoyed all of these discussions. They were, I think, for the most part, self-evident and self-contained and probably, therefore, do not need individual comment. I do thank Dr. De Bakey for rising to confirm that their experience with the sutureless valve parallels ours very closely. Moreover, it is rather difficult to get a cardiovascular series larger than that of Houston, but I did notice that we were still slightly ahead numerically, so if any of you see Dr. De Bakey leaving the meeting early, I would appreciate your letting me know about it. In reference to Dr. Bailey's remarks, certainly many of his objections to prosthetic materials are

Journal of

500

Lillehei et al.

Thoracic and Cardiovascular Surgery

well taken, at least on the basis of some past ex­ periences. Nonetheless, more recent research, knowledge, and experience has given us much more insight in the principles involved in the use of prosthetic materials implanted into human tis­ sue. I personally believe that we are well into an "Era of Prosthetic Replacement" in which we will see a vast expansion in the use of artificial materials to replace vital human tissues and, even, organs. I think that Dr. Starr's results are certainly admirable and I believe that we all owe both Dr. Starr and Mr. Edwards a great deal of credit for giving us a prosthetic valve that is good enough to make its routine use very feasible when de­ stroyed valves are encountered, which is so fre­ quently the case. In regard to Dr. Spencer's comments on coro­ nary perfusion, there were some differences on the three surgical services, in regard to its need; but I personally have felt that it is of utmost value, even when utilizing the sutureless valve, because

it takes only a minute or two as a rule to cannulate the two coronary arteries, and this allows one more time in sizing up the pathological anatomy and in excising the diseased valve. How­ ever, I regularly take out the left coronary artery cannula when sliding the sutureless valve down into position, because the fit should be very snug and one runs risk of damaging the left coronary artery orifice unless the cannula is temporarily removed. I appreciate Dr. Magovern's discussion. He and Mr. Cromie have been very helpful to us in con­ sultations about various aspects of the design and use of their valve. In regard to his suggestion about the use of a purse-string suture—I think one is always worried, in vascular surgery of this type, about the use of purse strings, because they are prone to either relax or cut through tissues. Thus, I have been hesitant and have not used a purse-string suture under these circumstances, even though I have known about this suggestion from him. Thank you very much.