Unusual Complications During Mitral Valve Replacement in the Presence of Calcification of the Annulus

Transcription

1 Unusual Complications During Mitral Valve Replacement in the Presence of Calcification of the Annulus Horace MacVaugh, 111, M.D., Claude R. Joyner, M.D., and Julian Johnson, M.D. ABSTRACT Replacement of the mitral valve with a prosthesis has become routine, and the operative mortality has steadily decreased. Although most operative deaths today are related to chronic pulmonary changes, arrhythmias, or low-output states, two groups of complications occur at specific areas along the mitral annulus that are related to the technique of valve insertion. Ligation of the left circumflex coronary artery occurs near the anterior commissure. Perforation of the high posterior left ventricle occurs along the posterior leaflet near the posterior commissure. Both these complications are more likely to occur in the presence of extensive calcification. Awareness of their likelihood should prevent these complications from occurring, but there are means of possible correction if the complication is recognized at operation. R eplacement of cardiac valves with prostheses has become a commonplace operation performed successfully in a wide range of hospitals. The operative mortality has declined a great deal since the early years of valve replacement, but it still amounted to 23% in a recent collected series [3]. Most of the deaths today are caused by postoperative pulmonary insufficiency, cardiac arrhythmias, or lowoutput syndromes due to a variety of causes. Technical errors are less frequent now that reliable routines for cardiopulmonary bypass and valve replacement have been developed. We have encountered two specific complications, the subtleties of which deserve special mention. From November, 1961, through November, 1969,253 mitral valve replacements were performed in the Hospital of the University of Pennsylvania. Ten patients have had complications at the posterior interatrial groove, generally in association with dense calcification of the posterior leaflet and annulus; their histories are presented below. Three of the 10 had fatal acute posterior myocardial infarctions, and 1 had a myocardial infarction with chronic aneurysm formation. Four patients had operative hemorrhage from the left ventricle, and 1 had From the Departments of Surgery and Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pa. Supported by U.S. Public Health Service Grants HE,-5239 and HE Accepted for publication July 29, Address reprint requests to Dr. MacVaugh, Hospital of the IJniversity of Pennsylvania, 3400 Spruce St., Philadelphia, Pa THE ANNALS OF THORACIC SURGERY

2 Complications During Mitral Valve Replacement delayed hemorrhage from the left ventricle. In 1 patient a subacute aneurysm of the left ventricle developed. All complications resulted either from too radical an excision of a calcified valve and annulus or from too deep a placement of the valve sutures. The incidence of such complications should be greatly reduced if the interrelationship of certain anatomical and pathological factors is thoroughly appreciated. PATIENT 1 A 49-year-old man with a long history of progressive cardiac failure was found to have severe mitral insufficiency with minimal calcification. After the valve leaflets were excised com letely, a No. 3 Starr-Edwards mitral prosthesis was implanted utilizing mild I? ypothermia (3OOC.1. Ventricular fibrillation occurred during the hypothermic period and required three direct-current shocks to restore sinus rhythm. The patient remained hypotensive following bypass, despite volume re lacement. He was slow to awaken and had persistent hypotension and low car B iac output. He died 24 hours postoperatively. At ostmortem examination the circumflex branch of the left coronary artery was P ound to be completely encircled and occluded 3 cm. from its origin by a suture placed to hold the mitral prosthesis. There was a large infarction of the left ventricle in the distribution of the ligated vessel. PATIENT 2 A 48-year-old woman had a fourteen-year history of progressive rheumatic heart disease. At operation a very heavily calcified valve was removed and replaced with a No. 2 mitral rosthesis. The calcification had extended into the atrial myocardium. She die1 24 hours after operation because of low cardiac output. Postmortem examination revealed that a suture was completely encircling the circumflex branch of the left coronary artery 3.5 cm. from its origin. There was a large, fresh infarct at the posterolateral wall of the left ventricle. PATIENT 3 A 40-year-old woman had become sym tomatic again following a closed mitral commissurotomy four years before. Kt operation the mitral valve was found to be densely calcified, and a large amount of thrombus was removed from the walls of the left atrium. A No. 2 Starr-Edwards prosthesis was implanted. Her condition began to deteriorate as bypass was discontinued, and vigorous volume replacement and inotropic agents failed to improve the hypotensive state. Postoperatively she remained hypotensive and cyanotic, and she died in a state of low cardiac output on the third postoperative day. At postmortem examination a suture was found piercing the circumflex branch of the left coronary artery about 3 cm. from its origin. This had caused a narrowing of the circumflex vessel, obliterating at least 80% of its lumen. There was a fresh posterior myocardial infarct measuring 4 x 5 cm. PATIENT 4 A 6-year-old boy had the combined congenital lesions of ventricular septa1 defect WSD) and mitral insufficiency. Although the VSD had been repaired adequately at the age of 4, he continued to have difficulty with congestive failure because of mitral insufficiency. At reoperation he was found to have a congenitally short posterior mitral valve leaflet which caused gross mitral insufficiency. The leaflets were excised and the valve replaced by a No. 5 Kay-Shiley prosthesis. The day following operation an electrocardiogram showed a QS pattern in leads 11, 111, and avf. There was prolonged difficulty with recurrent episodes of atrial

3 MAC VAUGH, JOYNER, AND JOHNSON and ventricular arrhythmia. This problem gradually subsided, and the patient was discharged one month postoperatively. He was readmitted four months after operation in severe congestive failure with gross cardiomegaly, and he died during a sudden episode of ventricular fibrillation. Postmortem examination revealed a large, fibrotic aneurysm of the entire posterior wall of the left ventricle. The left circumflex coronary artery, which supplied this area, was caught by a suture securing the prosthetic valve. The point of occlusion was 3 an. from the origin of the left circumflex coronary artery. PATIENT 5 A 67-year-old woman was found to have %cry tight rnitral stenosis. Her pulmonary artery pressure was approximately equal to the systemic artery pressure at 110 mm. Hg. Through a right thoracotomy the mitral valve was seen to be very heavily calcified. Her ventricular cavity was so small that a No. 1 Starr- Edwards mitral prosthesis was implanted. Following bypass, hemorrhage necessitated extension of the incision across the sternum into the left chest for better exposure of the posterior wall of the heart. The bleeding came from a thin area of myocardium just beneath the mitral valve annulus. The thinned muscle did not hold sutures, even when it was backed with Teflon felt, and the patient died of hemorrhage. At postmortem examination a short segment of the attachment of the ventricular myocardium to the mitral valve annulus was found to have been detached. This segment, 15 mm. long, was in the area of most extensive calcification along the posterior leaflet near the posterior commissure. PATIENT 6 A 50-year-old man had had progressive difficulty with chronic rheumatic heart disease over the previous three years. His mitral valve was heavily calcified, tightly stenotic, and moderately regurgitant. A No. 3 Siearr-Edwards valve was implanted through a right thoracotomy. Following bypass and closure of the heart, blood rapidly filled the pericardial cavity, The patient was turned partially supine, the sternum was transected, and the incision was extended into the left chest. There was a 2 an. rent in the posterior wall of the left ventricle. The myocardium was thin, but the rent was adequatelj closed with sutures backed with Teflon felt. He had an uneventful postoperative course and was discharged on the sixteenth day after operation. PATIENT 7 A 46-year-old man had had a previous closed mitral commissurotomy through the right chest. He developed recurrent mitral stenosis and had had a cerebral embolus. At reoperation, which was again through a right thoracotomy, his mitral valve was found to be extremely thick, densely fibrotic, and partially calcified. The valve was excised, and a No. 2 StamEdwards mitral vave thesis was inserted. Following bypass bright red blood was seen welling up p'"" rom behind the heart. Bypass was reinstituted, the patient was placed in a supine position, and the incision was extended across the sternum. The gartially leeding was found to come from an area at the atrioventricular groove near the posterior commissure. The muscle was quite soft and thin, but the hemorrhage was controlled, with difficulty, using a double row of 3-0 Tevdek sutures backed with Teflon felt. The patient was slow to awaken following the prolonged bypass but had an otherwise uneventful recovery. PATIENT 8 A 51-year-old man was found to have combined mitral stenosis and regurgitation with minimal aortic insufkiency. He was operated upon through the right chest, and the mitral valve was found to be heavily calcified. After excision of the diseased valve, a No. 2 StamEdwards prosthesis was inserted. When cardio- 338 THE ANNALS OF THORACIC SURGERY

4 Complications During Mitral Valve Replacement pulmonary bypass was discontinued, it was apparent that hemorrhage was occurring from a point posterior to the heart. Bypass was reinstituted, and after the heart was turned up, a small opening was found high on the posterior left ventricular wall. The hemorrhage was satisfactorily controlled by a single suture backed with Teflon felt, and the patient had an uneventful postoperative course. PATIENT 9 A 59-year-old woman had chronic rheumatic heart disease with calcific mitral stenosis and insufficiency. She had undergone a closed commissurotomy from the left chest eleven years previously. Through a right thoracotomy the mitral valve calcification was found to be extremely dense and to extend beyond the annulus. The valve was excised completely, including the calcium that extended into the annulus. A No. 8 Kay-Shiley valve was inserted. Although no hemorrhage was noted immediately following the procedure, the patient suddenly began to bleed one hour following operation while in recovery room. She was immediately returned to the operating room, and the thoracotomy was reopened. There was a large amount of blood in the chest and a large hematoma within the pericardium behind the heart. A laceration of the posterior wall of the left ventricle was visible just below the sewing ring of the valve. She died before bypass could be reinstituted. PATIENT 10 A 53-year-old man with a history of rheumatic fever had had a successful closed mitral commissurotomy from the left side eight years previously. Reevaluation established the diagnosis of severe calcific aortic stenosis and recurrent mitral valve disease. At reoperation his mitral and aortic valves were replaced with Starr-Edwards prostheses (Nos. 3M and 9A, respectively). The calcification at the posterior mitral commissure extended into the myocardium and was not completely removed. The atient was discharged three weeks after operation. Three months later he was F ound to have a spherical aneurysm 5 cm. in diameter arising from the posterior wall of the left ventricle. At a third operation the aneurysm was successfully resected and the orifice closed. The orifice measured 12 mm. in diameter and was located along the posterior wall near the posterior commissure, just beneath the sewing ring of the mitral prosthesis. The aneurysm was a thin-walled confluence of epicardium and pericardium [41. COMMENT Although these complications are directly attributable to techniques of insertion of a prosthesis, they fall into two categories. Those complications which occurred because of difficulties near the anterior commissure are different from the complications which occurred near the posterior commissure. LIGATION OF LEFT CIRCUMFLEX CORONARY ARTERY The first group consists of complications dependent upon the anatomical relationship between the left circumflex coronary artery and the mitral valve annulus (point A, Figure). Patients 1, 2, and 3 all died of acute posterior myocardial infarction secondary to ligation of the left circumflex coronary artery by a valve suture. Patient 4 developed a large posterior infarction with secondary aneurysm formation and died four months later of intractable left ventricular failure. Post- VOL. I I, NO. 4, APRIL,

5 MAC VAUGH, JOYNER, AND JOHNSON Point A illustrates the site of fatal ligation of the left ciwumpex coronary artery by valve suture. Point B illustrates the area of densest calcification, the excision of which has led to perforation of the left ven;!ricle. mortem findings showed encirclement of the left. circumflex coronary artery by a valve suture. In all these patients the point of ligation was 2.5 to 3.5 cm. from the origin of the left circumflex coronary artery. It is within this distance that the artery is both vulnerable and of a large enough size for ligation to cause a serious, perhaps fatal infarction. If ligation occurs within this distance, the myocard.ium supplied by the marginal artery is also rendered ischemic. The marginal artery is the first and usually the largest branch of the circumflex coronary artery and most often arises at about 3.5 cm. from the origin of th:is artery. The circumflex artery becomes much smaller beyond this point and usually descends slightly from the annulus; hence it becomes less vulnerable. A large group of patients may be protected from ligation of the left circumflex coronary artery because, according to James [2], this vessel completely terminates at or before the obtuse m.argin of the heart in 22% of the population. Therefore, in nearly a quarter of patients no posterior suture is likely to encircle a major coronary artery. In the 4 patients in whom this complication occurred, the suture encircled the circumflex coronary artery before the origin of a large marginal artery. Overenthusiastic excision of calcification in the area of the anterior commissure may have contributed to the likelihood of 340 THE ANNALS OF THORACIC SURGERY

6 Complications During Mitral Valve Replacement this complication. The calcification must be removed carefully and perhaps incompletely in order to leave sufficient annulus to hold valve sutures. A prosthetic reconstruction of the annulus has been proposed by Danielson and associates [l] in order to avoid this complication. This maneuver should be necessary only rarely if careful judgment is used during valve excision. The small size of the heart and annulus in Patient 4 may have predisposed him to this complication. The size factor must be considered during valve replacement in children. The complication was not diagnosed until postmortem examination in any of these patients, although it had been obvious that none of them came off bypass well. Each had refractory hypotension, and 2 were noted to be cyanotic while still in the operating room. Ventricular fibrillation occurred in 1 patient under operative conditions which generally do not produce this in our clinic. In the 6-year-old patient there probably was electrocardiographic evidence of infarction in the operating room, although this observation was not made conclusively until the next day. In short, there are clues to the presence of the complication at a time when repair might be possible. It would require convincing evidence for a surgeon to be willing to reinstitute bypass, reopen the heart, and replace the sutures which held the prosthesis. The clinical evidence described above and the observation of a pale, cyanotic, noncontractile area in the posterior left ventricle should suggest the possibility that left circumflex coronary artery ligation threatens. Three or four sutures might be removed from an area centered on point A (see Figure), representing perhaps one-sixth of the circumference of the annulus. PERFORATION OF LEFT VENTRICLE The second group among our 10 patients had complications at point B (see Figure). These complications did not involve the circumflex coronary artery as was the case in the first group. At location B the circumflex coronary artery has terminated, is too small to cause a fatal lesion if ligated, or has descended along the ventricular wall and is out of jeopardy. The complication in the second group of patients was hemorrhage, which occurred from a myocardial perforation high in the posterior left ventricular wall, nearly always in association with dense calcification of the posterior leaflet. Calcification of a rheumatic valve is often most dense in the posterior leaflet near the posterior commissure. At point B (see Figure) the relationship of the mitral valve and left ventricular wall are shown. The myocardial trabeculation may be quite thin. This whole region may be calcified, and the calcification may extend through the annulus VOL. 1 1, NO. 4, APRIL,

7 MAC VAUGH, JOYNER, AND JOHNSON to the muscle itself. If the calcification :is completely cut away, there will be a defect in the ventricular wall. 'This apparently happened in Patients 5, 6, 7, and 8. Other complications may occur if an epicardial layer remains, even though nearly all the fibromuscular transition zone is excised. There may be delayed hemorrhage, as in Patient 9, or even aneurysm formation, as in Patient 10. Both of these patients had had previous cardiotomies. Perhaps the resultant intrapericardial adhesions helped prevent what might otherwise have been iikraoperative hemorrhage. It is important to recognize the possible extent of calcific involvement of the mitral valve, particularly near the posterior commissure. One should not endeavor to excise all calcification if it appears to extend through the annulus. Although a calcified: bed is not an ideal seat for a prosthetic valve, a secure and leak-proof fixation can be attained with careful suture technique. The calcified tissue is friable, and the problem is fragmentation more often than impenetrability. If a ventricular perforation does occur the situation may be corrected by the accurate placement of mattress sutures backed with felt. In 3 of the 4 patients in whom this complication was recognized we were able to rectify the situation in this manner. Because all these patients were operated upon through the right chest, it was necessary to turn the patient partially supine, transelct the sternum, and enter the left chest in order to gain adequate exposure of the perforation. Surgeons who approach the mitral valve through the midline or left chest should have less difficulty gaining exposure if this complication occurs. REFERENCES 1. Danielson, G. K., Cooper, E., and Tweeddale, D. M. Circumflex coronary artery injury during mitral valve replacement. Ann. Thorac. Surg. 4:53, James, T. N. Anatomy of the Coronary A,rteries. New York: Hoeber, Kittle, C. F., Dye, W. S., Gerbode, F., Glenn, W. W. L., Julian, 0. C., Morrow, A. G., Sabiston, D. C., Jr., and Weinberg, M. Factors influencing risk in cardiac surgical patients: Cooperative study. Circulatibn (Suppl. I): 169, MacVaugh, H., 111, Joyner, C. R., Pierce, W. S., and Johnson, J. Repair of subvalvular left ventricular aneurysm occurring as a complication of mitral valve replacement. J. Thorac. Cardiovusc. Surg. 58:2!)1, Editor's Note: The authors have described two important complications of mitral valve replacement that deserve emphasis. They are to be congratulated for saving patient:; with ptrrforation of the left ventricle during mitral valve replacement. This c,omplication has often been fatal. 342 THE ANNALS OF THORACIC SURGERY