prosthetic replacement of the mitral or aortic valves: a preliminary report on 111 cases

6
Prosthetic Replacement of the Mitral or Aortic Valves A Preliminary Report on 111 Cases* THO~,\S G. NELSON, Lt. Cal., MC, LISA, and DENTON A. COOLEY, M.D., F.A.C.C. Houston, Texas W ITH increasing experience in mitral and aortic valve repair, the need for total valve replacement in patients with functionless valves has become apparent. Development of the ball and seat type of valve by Starr and Edwards’,2 now offers a promising method of substitution which is replacing other technics of surgery for the destroyed mitral or aortic valve.Y This report reviews an experience during the past year in the use of the Starr- Edwards valve for mitral and aortic disease in 111 patients. Forty-eight patients had mitral valve replacement, 61 had aortic replacement, and 2 patients had both valves replaced simul- taneously. Patients were selected for replacement of valves only when no other satisfactory means of medical or surgical management was available. For example, patients with noncalcific mitral and aortic stenosis and mitral annular dilata- tion were treated by valvulotomy4 or annulo- plasty. The patients undergoing replacement were not amenable to the above methods of treatment because of destroyed valves from dense calcification and loss of valve substance. In such cases results of debridement, sculptur- ing and replacement or repair of individual valve leaflets were generally unsatisfactory in our cases. Over 20 per cent of the 111 patients had recurrence of valve disease after a previous repair. All patients had progressive cardiac deterioration, and many had intractable heart failure with pulmonary congestion and hepato- megaly despite intensive medical treatment. TECHNICAL CONSIDERATIONS A simplified technic of cardiopulmonary bypass, consisting of a disposable oxygenator, 5% dextrose prime and normothermia, now used successfully in over 600 open heart operations, was employed in all valve replacements.6S6 Flow rates were main- tained at 2,800 to 3,600 ml./min. during the period of bypass, which averaged 33 minutes for either type of valve replacement. Venous outflow from the heart was obtained either by cannulation of the superior and inferior vena cava or by a single large cannula in the right atrium or right ventricle. Return of oxygenated blood to the patient was by the common femoral artery. During either type of valve replacement, the left side of the heart was vented with a cannula placed usually in the apex of the ventricle. At the termination of bypass, air embolism was prevented by carefully venting and refilling the heart chambers, meanwhile lowering the patient’s head for a brief period to prevent cerebral air embolism. Mitraf Valve Replacement: Either a left or right anterior thoracotomy with sternal transection was employed. The left approach was utilized unless a previous cardiac operation had been performed on this side. From the left, the mitral valve was exposed through an atriotomy posterior to the appendage, while from the right, the left atrium was opened posterior to the interatrial groove. With either approach, care was exercised to occlude the ascending aorta until the left side of the heart was empty of blood to prevent air being forced into the aorta by the active left ventricle. Once the left heart was emptied, the aortic clamp could be opened to permit myocardial perfusion with normothermic oxygenated blood without danger of air embolism. If a non- calcified regurgitant valve with annular dilation was present, the repair was done by annuloplasty only. Calcified valves were completely excised, including the chordae tendineae. Aortic Valve Replacement: A median sternotomy and a transverse aortotomy were employed for aortic valve exposure. The left coronary artery was cannulated, and perfusion of the myocardium with * From the Cora and Webb Mading Department of Surgery, Baylor University College of Medicine, and the Surgical Service of St. Luke’s Episcopal Hospital, Houston, Texas. 148 THE AMERICAN JOURNAL OF CARDIOLOGY

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Page 1: Prosthetic replacement of the mitral or aortic valves: A preliminary report on 111 cases

Prosthetic Replacement of the Mitral or

Aortic Valves

A Preliminary Report on 111 Cases*

THO~,\S G. NELSON, Lt. Cal., MC, LISA, and DENTON A. COOLEY, M.D., F.A.C.C.

Houston, Texas

W ITH increasing experience in mitral and

aortic valve repair, the need for total

valve replacement in patients with functionless

valves has become apparent. Development of the ball and seat type of valve by Starr and Edwards’,2 now offers a promising method of substitution which is replacing other technics of surgery for the destroyed mitral or aortic valve.Y This report reviews an experience during the past year in the use of the Starr- Edwards valve for mitral and aortic disease in 111 patients. Forty-eight patients had mitral valve replacement, 61 had aortic replacement, and 2 patients had both valves replaced simul- taneously.

Patients were selected for replacement of valves only when no other satisfactory means of medical or surgical management was available. For example, patients with noncalcific mitral and aortic stenosis and mitral annular dilata- tion were treated by valvulotomy4 or annulo- plasty. The patients undergoing replacement were not amenable to the above methods of treatment because of destroyed valves from dense calcification and loss of valve substance. In such cases results of debridement, sculptur- ing and replacement or repair of individual valve leaflets were generally unsatisfactory in our cases. Over 20 per cent of the 111 patients had recurrence of valve disease after a previous repair. All patients had progressive cardiac deterioration, and many had intractable heart failure with pulmonary congestion and hepato- megaly despite intensive medical treatment.

TECHNICAL CONSIDERATIONS

A simplified technic of cardiopulmonary bypass, consisting of a disposable oxygenator, 5% dextrose

prime and normothermia, now used successfully in

over 600 open heart operations, was employed in

all valve replacements.6S6 Flow rates were main-

tained at 2,800 to 3,600 ml./min. during the period of bypass, which averaged 33 minutes for either type of valve replacement. Venous outflow from the heart was obtained either by cannulation of the superior and inferior vena cava or by a single large cannula in the right atrium or right ventricle. Return of oxygenated blood to the patient was by the common femoral artery. During either type of valve replacement, the left side of the heart was vented with a cannula placed usually in the apex of the ventricle. At the termination of bypass, air embolism was prevented by carefully venting and refilling the heart chambers, meanwhile lowering the patient’s head for a brief period to prevent cerebral air embolism.

Mitraf Valve Replacement: Either a left or right anterior thoracotomy with sternal transection was employed. The left approach was utilized unless a previous cardiac operation had been performed on this side. From the left, the mitral valve was exposed through an atriotomy posterior to the appendage, while from the right, the left atrium was opened posterior to the interatrial groove. With either approach, care was exercised to occlude the ascending aorta until the left side of the heart was empty of blood to prevent air being forced into the aorta by the active left ventricle. Once the left heart was emptied, the aortic clamp could be opened to permit myocardial perfusion with normothermic oxygenated blood without danger of air embolism. If a non- calcified regurgitant valve with annular dilation was present, the repair was done by annuloplasty only. Calcified valves were completely excised, including the chordae tendineae.

Aortic Valve Replacement: A median sternotomy and a transverse aortotomy were employed for aortic valve exposure. The left coronary artery was cannulated, and perfusion of the myocardium with

* From the Cora and Webb Mading Department of Surgery, Baylor University College of Medicine, and the Surgical Service of St. Luke’s Episcopal Hospital, Houston, Texas.

148 THE AMERICAN JOURNAL OF CARDIOLOGY

Page 2: Prosthetic replacement of the mitral or aortic valves: A preliminary report on 111 cases

149 Prosthetic Valve Replacement

A B FIG. 1. Figure-of-eight suture technic used for either mitral (A) or aortic (B) valve replacement. Inset: Seating position of the mitral (A) and aortic (B) valve after sutures were tied.

normothermic oxygenated blood was continued until the aortotomy was closed. Volume of coronary perfusion was controlled by monitoring the mean-line pressure at 90 to 100 mm. Hg. Excision of the markedly calcified valve was often difficult, and ex- treme care was exercised to remove most of the calcium without weakening the annular wall or interfering with the adjacent A-V conduction bundle.

Combined Mitral and Aortic Replacement: A median sternotomy and separate incision at the right fourth intercostal space were utilized for combined valve replacement. Both incisions were completed prior to beginning complete cardiopulmonary bypass. The intercostal incision was not continued across the sternum, and additiona exposure was ob- tained by dividing the fourth costal cartilage. The aortic valve was replaced first, then the mitral valve. Coronary artery perfusion was utilized during the aortic valve replacement. After closure of the aortotomy, the aorta was left unclamped for continued myocardial perfusion during mitral re- placement.

Technic of Valve Placement: For either type of valve replacement, double:armed 2-O dacron sutures were placed in the remaining annular tissue by using a figure-of-eight technic (Fig. 1). Each suture limb was then passed through the sewing ring of the pros- thesis in mattress fashion. Initial sutures were placed at the commissures for traction and orientation; then the remaining sutures were spaced appropriately. After placement of all sutures, the valve was seated and the sutures tied. This figure-of-eight suturing technic sealed and fixed the prosthetic sewing ring to

VOLUME 14, AUGUST 1964

the recipient tissue better than did simple interrupted or mattress sutures.

POSTOPERATIVE MANAGEMENT

All patients received prophylactic antibiotic therapy. Digitalis was continued if the patient was digitalized prior to operation, but in many instances digitalis could be discontinued after valve function was restored. Diuretics were used only on specific indication and manni- to1 was not employed. Blood replacement was controlled carefully to avoid overtransfusion. The average blood replacement for all patients throughout hospitalization was 1,600 ml. Patients with severe pulmonary hypertension or congestion were managed with tracheostomy and assisted positive pressure ventilation for 24

to 72 hours after operation. In the mitral replacement group only, prophylactic anti- coagulants were administered beginning on the fifth day after operation and continuing for at least three months.

CLINICAL DATA

The age of the 71 male and 40 female patients ranged from 15 to 72 with a bout 60 per cent between 40 and 60 years (Table I). Con- gestive heart failure, angina pectoris, serious cardiac arrhythmias and syncope, presenting in various functional combinations, placed 63

Page 3: Prosthetic replacement of the mitral or aortic valves: A preliminary report on 111 cases

150 Nelson and Cooley

~I‘ABLli 1

Age Range of Patients with Mitral or Am-tic Valve, Replacements

Age Range (yr. 1 Mitral Aortic Combined ‘l‘otal

10-19 20-29 30-39 40-49 50-59 60-69 70-79

Total

3 1 4 6 6 12

II 6 .I 18 15 20 35 14 14 28 2 10 12

48 2 2

61 2 111

Clinical Data of Patients with Mitral or Aortic Valve Replacement

Associated Clinical Condition Mitral Aortic Combined

__~__ __-_

Total no. of patients Left heart failure Pulmonary edema Angina, syncope,

48 61 2 48 49 2 20 20 1

arrhythmias 24 24* I Atria1 fibrillation 30 15 1 Right heart failure 16 6 1 Multiple valve involvement 15 19 2 Coronary artery disease 8 20 Previous surgery 17 8 Aortic aneurysm 5 .:

* Twelve of these did not have heart failure.

patients in class III and 48 patients in class IV (Table II). In the class IV group 10 deaths (5 mitral, 5 aortic) occurred among the 48 patients for a mortality rate of 21 per cent, while in the class III group there were 5 deaths (2 mitral, 3 aortic) among 63 patients for a mortality rate of 8 per cent. Of interest were 2 female patients 72 years of age in the class IV group who underwent aortic valve replacement with a remarkable improvement after opera- tion. The severe cardiac functional impairment present in all patients was further substantiated from physiologic data obtained by right and left heart catheterization, associated coronary insufficiency evident on electrocardiograms, and recurrence of valve disease after previous surgery.

Mitral Valve Lesions: All 12 patients with mitral stenosis and 30 of 36 patients with regurgitation had a history of previous rheumatic fever (Table III). Most patients gave a history

‘I‘ABLE III

btiology of Valvular Disease in Mitral or Aortic Valve Replacement

Other and Rheumati< Con- Un-

\‘alw IXsei~sc Pew Cslclfir* Kenitalt determiner1

-____-.__ ~I_

Aor-tic stenosis 11 x 7 7 Aortic insufficiency I6 3 *f 7% .Mitral stenosis 12 Mitral insuffirienry 30 2 4 Combined 2

Total 71 13 ; ;a

* No history of rheumatic fever. t With acquired changes. t One had Marfan’s syndrome. 5 Two each had traumatic and loetic insufikiency.

of prolonged pulmonary congestion and many had hepatomegaly, angina and arrhythmias. Thus, despite strict medical therapy, most patients were severely limited in exercise capacity or even confined to bed. Seventeen patients had recurrence of disease over varying periods of time up to seven years after either commissurotomy for mitral stenosis or annulo- plasty for insufficiency. Serious pulmonary hypertension was present in virtually every patient when measured by right heart catheterization. The lowest and highest mean pulmonary pressures recorded were 25 and 70 mm. Hg with an average mean pressure of 40 mm. Hg (Table IV). All deaths occurred in those with pressures higher than the average.

dortic Valve Lesions: Rheumatic fever pre- dominated also as the causative agent in this

group. Of interest were 7 cases of apparent congenital stenosis with secondary calcification and 5 cases of insufficiency; 2 with traumatic rupture of a valve cusp, 2 with luetic aneurysms, and one with Marfan’s syndrome (Table III).

Left heart failure occurred in 49 of the 61 patients and was serious enough to cause frank pulmonary edema in 20 of these. Twelve others have angina, cardiac arrhythmias and syncope which warranted valve replacement in the absence of failure. Disability recurred in 8 patients two months to three+ years after other types of valve repair, and in 1 patient in whom a Starr-Edwards valve prosthesis became de- tached.

Multiple Valvular Lesions: Thirty-six patients had disease of both mitral and aortic valves. Two of these required simultaneous replace- ment of valves because of severe insufficiency in both locations. In the remaining 34 patients the predominantly affected valve was replaced,

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Page 4: Prosthetic replacement of the mitral or aortic valves: A preliminary report on 111 cases

Prosthetic Valve Replacement 151

TABLE IV Pulmonary Artery Pressures: Relationship to Mortality

in 32 Mitral Valve Replacements

No. of No. of Patients Deaths

-.

Catheterization 32 7 Pulmonary artery pressures (mm. Hg)

Systolic loo+ 2 2 80-100 10 4 60-80 12 1 40-60 8 0

Mean 60-80 2 2 40-60 16 5 20-40 14 0

and no additional procedure was required for the valve with lesser involvement.

RESULTS

The over-all mortality rate of 13.5 per cent included both early and late deaths (Table v). The mortality rate in the last 89 patients was approximately 9 per cent, one third of that for earlier cases. Operations in patients having severe pulmonary hypertension, pulmonary edema, both left and right heart failure and previous valve repair produced a higher than average risk. Though present in 25 per cent of patients, coronary artery disease was not a significant factor in mortality. One early death due to coronary occlusion occurred after mitral valve replacement in a patient not suspected previously of having coronary disease, and one late death after an aortic valve re- placement was due to blockage of a coronary ostium by a propagating thrombus from the adjacent prosthesis.

Development of an arrhythmia not present prior to surgery was the most frequent post- operative complication, while myocardial failure was the commonest cause of death (Table VI). The deaths attributed to myocardial failure included 2 patients with aortic valve disease and enormous ventricular hypertrophy in whom cardiac function could not be restored immediately following cardiopulmonary by- pass and 2 others with mitral disease and severe pulmonary hypertension who died of intract- able pulmonary congestion.

Systemic infection occurred in 3 patients, each of whom had a previous history of bacterial endocarditis. Two deaths resulted, while the

VOLUME 14, AUGUST 1964

TABLE v Mortality in Mitral or Aortic Replacement

Valvular Disease

No. of Deaths Patients Hospital Late

Total Deaths (no.1 (x4

Aortic stenosis 33 3 2 5 (15 1) Aortic insufficiency 28 3 0 3 (10.7) Mitral stenosis 12 2 0 2 (16.7) Mitral insufficiency 36 4 1 5 (13 9) Combined 2 0 0 0 ( 0 0)

Total 111 12 3 15 (13.5)

TABLE VI

Complications and Causes of Death in Mitral or Aortic Valve Replacement

Complication

Early

No. o.

No. Deaths __-

Cardiac arrhythmias 10 2 Hemorrhage 6 2 Myocardial failure 5 4 Cerebral air embolism 4 2 Renal failure 3 1 Coronary artery occlusion 1 1

Late

Infection 3 2 Arterial embolism 4 0 Thrombus occluding coronary ostium 1 1 Post-pericardiotomy syndrome 3 0 Detached prosthesis 1 0

Total (early and late) 41 15

third patient recovered after treatment. Four patients, 3 with mitral and 1 with aortic valve replacement, had late embolic complications. Two of these patients are currently disabled because of cerebral emboli, but the other two recovered after embolization to the extremities.

Within two to three months after operation most patients returned to normal activity, and most of the patients under 60 years of age returned to work. Among 60 patients operated upon more than three months ago, 3 are now incapacitated, 2 because of cerebral emboli and 1 because of infection. A smaller group of patients followed-up more than six months demonstrate relative freedom from symptoms, increased exercise tolerance and reduction in cardiac size (Fig. 2).

DISCUSSION

Initially valve replacement was restricted to a

Page 5: Prosthetic replacement of the mitral or aortic valves: A preliminary report on 111 cases

in cardiac size six months al’trr x al\ c rrplacemcnt.

group of totally incapacitated patients wit11 a single destroyed valve. The encouraging results in this group led to a broader selection of candidates to include those with multiple valve disease and other cardiovascular ab- normalities. At the present time, patients with coronary artery disease, Marfan’s syndrome, luetic aneurysms of the aorta as well as those with secondary valve involvement are doing well following valve replacement. The satisfactory results obtained after valve replacement-even when intractable cardiac decompensation, severe pulmonary hypertension and associated hazards were all present-justified this broad selection of candidates for operation. Furthermore, it now seems warranted to recommend valve replace- ment for patients with lesser degrees of dis- ability in whom total incapacity within a short period of time can be foreseen. It is anticipated that the same or better results will be obtained with less operative risk.

The advantages previousiy reported for the technic of cardiopulmonary bypass now used in all open heart operations by us5 were further substantiated in this group of patients. The physiologic benefits included freedom from electrolyte disturbances, renal failure, pul- monary complications and bleeding problems.” After operation, the patients awakened promptly

without inental confusion and with normal resumption of pulmonary and renal function. The simplicity with which the extracorporeal circuit was established provided desirable flexi- bility and shortened both anesthetic and bypass times. The reduced time of anesthesia and cardiopulmonary bypass are decided benefits in patients with a reduced cardiac reserve. The simplified technic of cardiopulmonary bypass, however, is not restricted to short procedures, nor does it demand hasty intracardiac repair. Two patients undergoing double valve re- placement tolerated cardiopulmonary bypass for over 70 minutes each, with no untoward effect.

During the period of bypass an effort was made to keep the heart contracting quietly at a near-normal rhythm by controlling coronary blood flow. This degree of cardiac activity did not interfere with the intracardiac procedure; resuscitation at the termination of bypass was simplified, and there was less risk of an un- recognized injury to conduction. During mitral valve replacement, this desired cardiac state was obtained by leaving the aorta unoccluded for myocardial perfusion throughout the time of cardiopulmonary bypass. Several technics of coronary artery perfusion during aortic valve replacement were evaluated. In a series of 25

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Page 6: Prosthetic replacement of the mitral or aortic valves: A preliminary report on 111 cases

Prosthetic Valve Keplacement 153

patients coronary perfusion was omitted entirely. .Although this did not affect subsequent survival of the patient, cardiac resuscitation was more difficult and time consuming at the termination of bypass. A comparison of bilateral with single artery perfusion revealed no difference in obtaining the desired cardiac response during bypass, or later during resuscitation. In all recent aortic valve replacements, left coronary artery perfusion alone has been utilized. Air embolism was not a problem if the ascending aorta was clamped before making the cardio- tomy incision and if the heart was properly vented and refilled at the termination of bypass.

The technic combining normothermia and myocardial perfusion provided almost immediate resumption of normal cardiac contraction upon termination of bypass, and countershock to correct ventricular fibrillation was necessary in only 10 per cent of cases. When defibrillation was required, the direct current (D.C.) de- fibrillator provided prompt conversion to a sinus rhythm and was superior to defibrillators that utilized alternating current.

After operation, Lown’s method? of syn- chronized monopulse defibrillation was used effectively to correct atria1 fibrillation occurring in patients with previous sinus rhythm. The simplicity and ease of conversion by this tech- nic have been sufficiently convincing so that at the present time no patient with atria1 fibrilla- tion is discharged from the hospital without an attempted conversion.

Profihylactic anticoagulant therapy was not used in the early patients unless there was a history of previous embolism or the atrium contained thrombus at the time of operation. Recently, because of embolic accidents occurring pre- dominantly in the mitral group, all patients undergoing mitral valve replacement receive anticoagulant therapy. The patients with aortic valve replacement even now do not re- ceive prophylactic anticoagulants. Late throm- boembolic complications may ultimately prove to be the major late complication and dis- advantage of valve replacement with synthetic materials. Thus, the operation should at present be offered to only those patients with severe valvular disease.

SUMMARY

Total replacement of the aortic or mitral

\-alvc with a ball and seat prosthesis was used in a consecutive series of 111 patients with a mortality rate of 13.5 per cent. In the first 22 operations, 7 deaths occurred (32%;,), whereas in the last 89 operations there were only 8 deaths (9%), indicating the itnprovetnent in surgical technic and management. The valves were inserted during temporarv cardiopul- monary bypass under normotherm’ic conditions, using 5% glucose in distilled water to prime the pump oxygenator, eliminating the need for fresh, heparinized blood.

Ages of the patients ranged between 15 and 72 and 2 patients undergoing successful aortic valve replacement were more than 70 years of age. Embolic phenomena after operation occurred in 4 patients, 3 of whotn had prosthetic mitral valves. One patient with an aortic replacement had thrombosis of the valve ring with occlusion of the left coronary ostium. Prophylactic anticoagulants were used in all recent mitral replacements, but not in aortic valve replacements.

Surviving patients have been improved, and many are engaged in normal activity. At present, total valve replacement offers an effective means of treatment for advanced mitral and aortic valvular disease with a relatively low surgical risk.

REFERENCES

1. STARR, A., EDWARDS, M. L., MCCORD, M. C. and GRISWOLD, H. E. Aortic replacement: Clinical experiences with semirigid ball-valve prosthesis. Circulation, 27: 779, 1963.

2. STARR, A., EDWARDS, M. L. and GRISWOLD, H. E. Mitral replacement; late results with a ball-valve prosthesis. Prog. Cardiovns. Dir., 5: 298, 1963.

3. EFFLER, D. B., GROVES, L. K. and FAVALORO, R. Aortic and mitral valve replacement: Experience with Starr-Edwards prostheses. A.M.A. Arch. slog., 88: 145, 1964.

4. COOLEY, D. A. and STONEBURNER, J. M. Trans- ventricular mitral valvotomy. Surgery, 46 : 414, 1959.

5. COOLEY, D. A., BEALL, A. C., JR. and GRONDIN, P. Open heart operations using disposable oxygena- tors, 5 per cent dextrose prime, and normothermia: Experimental and clinical considerations. Surgery, 52: 713, 1962.

6. BEALL, A. C., JR. and COOLEY, D. A. Physiological studies during cardiopulmonary bypass eliminating heparinized blood. Dis. Chest, in press.

7. LOWN, B., AMARASINGHAM, R. and NEUMAN, J. New method for terminating cardiac arrhythmias. J.A.M.A., 182: 598, 1962.

VOLUME 14, AUGUST 1964