by Excision and Homograft Valve

Transcription

1 Mycotic Aneurysm of the Aortic Root and Infected Prosthetic Valve Treated by Excision and Homograft Valve Replacement Donald G. Mulder, M.D., and B. Lamar Johnson, Jr., M.D. A mong the most serious complications of aortic valve replacement is infection of the prosthesis and aortic root. Sterilization of the bloodstream with optimal antibiotic therapy is frequently impossible, although occasional cures with chemotherapy alone have been reported [5, 71. Even if bacteriological cure is achieved, the patient often has severe aortic insufficiency as a result of partial detachment of the prosthesis. Surgical exploration with debridement of infected tissue and replacement of the prosthesis is a recognized adjunct to chemotherapy when active infection cannot be controlled with antibiotics alone. The following case of unusually complicated aortic root infection in which an aortic homograft was used successfully to replace an infected prosthetic valve is presented to emphasize this alternative form of treatment. The patient was a 15-year-old boy in whom a heart murmur had been noted at age 3 months. He had undergone a diagnostic evaluation in April, 1964, at the age of 11 years which revealed clinical and aortographic evidence of aortic insufficiency. It was believed at that time that he had an aneurysm of the sinus of Valsalva or an aortico-left ventricular tunnel. During surgical exploration in June, 1964, a fistula of the right coronary sinus of Valsalva had been found. Finger palpation within the right atrium and ventricle failed to reveal any communication, and it was assumed that the aneurysm communicated with the left ventricle. The orifice was closed by direct suture, and an annuloplasty was performed because of redundancy and incompetence of the aortic cusps. An additional finding was an unusual bulging at the base of the heart just cephalad to the site of the repair, suggesting a localized aneurysm of the left ventricle. No attempts were made to correct this. Shortly after operation, the findings of aortic insufficiency were again noted, and in August, 1967, the patient (age 14) was again operated upon by a different surgical team. The previously noted sinus of Valsalva fistula had recurred. The fistula, which was believed to represent the aortic orifice of an aorticwleft From the Departments of Surgery and Medicine, UCLA Medical Center, Los Angeles, Calif. Accepted for publication Oct. 16, Address reprint requests to Dr. Mulder. Department of Surgery, UCLA Medical Center, Los Angeles, Calif VOL. 9, NO. 3, MARCH,

2 MULDER AND JOHNSON ventricular tunnel, was again sutured with buttressing pledgets for reinforcement. In addition, the aortic cusps which had multiple fenestrations were excised and a No. 9 Starr valve was inserted. No diastolic murmur was present in the postoperative period. The patient was treated with methicillin following the surgical procedure and was discharged on a daily regimen of Lanoxin 0.30 mg. and Coumadin 10 mg. He did well until October 16, 1967, when he developed chills and fever as well as transient tenderness over the pad of the left thumb and over the olecranon process of the left ulna. He was admitted to the hospital on October 26, 1967, and was found to have a temperature of 104O, blood pressure 110/60, a loud aortic diastolic murmur, clubbing of the fingers and toes, and a palpable spleen 6 cm. below the left costal margin. Results of urinalysis were normal; hemoglobin was 12.6 gm. per 100 ml.; and white blood count was 13,600 cells per cubic millimeter with a shift to the left. Six blood cultures were positive for a micrococcus. He was started on a regimen of 2 gm. of cephalothin given intravenously every 4 hours and 5 mg. of kanamycin per kilogram of body weight given intramuscularly every 8 hours. Rapid lysis of fever resulted. He developed recurrent fever on November 12, 1967, and blood cultures were again positive for a micrococcus. Because of persistently positive blood cultures in the face of optimal antibacterial therapy, he was reoperated upon November 28, 1967, by the original surgical team. The surgeons found a recurrence of the sinus fistula forming the aortico-left ventricular tunnel which was widely opened and repaired. A mycotic aneurysm of the aortic root was excised, and the grossly infected prosthetic valve was replaced with a low-profile disc valve. The aortic root was repaired by direct suture. The micrococcus was again isolated from the surgical specimen. Postoperative bleeding necessitated exploration, which was well tolerated. The patienwas placed on a regimen of 3 gm. of cephalothin every 4 hours, and kanamycirl therapy was continued. These drugs were discontinued on January 12, 1968, and he was started on a regimen of 1 gm. of cloxacillin given orally every 4 hours. The patient remained asymptomatic on this regimen until May 28, when he developed a transient episode of recurrent fever. At this time blood cultures again revealed a micrococcus, and he was admitted for the first time to the UCLA Medical Center. He gave a history of increasing dyspnea on exertion, palpitation, and orthopnea for 2 weeks prior to admission. Physical examination revealed a blood pressure of 120/50, bilateral basilar rales, a left ventricular heave, a Grade 4 of 6 diastolic murmur along the left sternal border, and hepatosplenomegal y. The hematocrit reading was 40%, and the leukocyte count was 6,000 cells per cubic millimeter with 61% segmented neutrophils, 29% lymphocytes, 6% monocytes, and 4% undifferentiated mononuclear cells of differential blood count. Results of urinalysis and serum electrolyte, creatinine, and serum glutamic pyruvic transaminase (SGPT) readings all were normal. The electrocardiogram showed a ventricular conduction delay, and on chest roentgenogram generalized cardiomegaly, aortic dilatation, and pulmonary venous congestion were noted (Figure). The patient was treated with digoxin, Coumadin, Lasix, and a salt-restricted diet, as well as with 2 gm. of cephalothin given every 4 hours intravenously. Although he was not febrile, a gentamicin dose of 0.4 mg. per kilogram of body weight given intramuscularly every 8 hours was added to the antibiotic regimen when the results of in vitro antibiotic sensitivity tests showed that the organism isolated from the blood was sensitive to this agent. Because of progressive deterioration in the face of intensive medical therapy, operation was again recommended. On June 20, 1968, the patient underwent his fifth median sternotomy and fourth open-heart procedure. As the sternotomy was being performed, a recurrent mycotic aneurysm of the ascending aorta eroding the posterior table of the sternum was entered, producing massive hemorrhage with hypotension which 254 THE ANNALS OF THORACIC SURGERY

3 CASE REPORT: Infected Prosthetic Valve Chest roentgenogram of patient prior to excision of a mycotic aneurysm of the ascending aorta and an infected prosthetic valve. Pulmonary vascular congestion and cardiomegaly are apparent. lasted approximately 10 minutes until completion of the sternotomy and digital control of the bleeding were accomplished. After bypass had been hurriedly instituted, the mycotic aneurysm and the infected, partially detached prosthetic valve were excised. No communication from the aortic sinus to the left ventricle was apparent. After further debridement of the aortic root, a formalin-preserved homograft aortic valve was inserted. Preplaced interrupted sutures of 3-0 Tev-Dek were used to secure the lower margin of the graft. A continuous suture of the same material following the contour of the valve cusps formed the second layer. An additional mattress suture was placed at each commissural angle and tied over a bolster to add further support. Extensive mobilization of the remaining ascending aorta made it possible to close the aortotomy by direct suture so that a prosthetic graft was not necessary. The patient s postoperative course was uncomplicated, although he did experience a transient right hemiparesis and mental confusion which cleared completely within the first week. No murmur was audible during the first postoperative week, and his blood pressure was 100/70. The operative specimen revealed a micrococcus identical to the one isolated from the blood. He was continued on a regimen of cephalothin and gentamicin until he was discharged on July 25, 1968, at which time the cephalothin was discontinued. A Grade 2 diastolic murmur was audible at this time. His blood pressure was 100/ He was afebrile, and the previous hepatosplenomegaly was unchanged. Over the ensuing year he has remained asymptomatic even with moderate exertion. The diastolic murmur and blood pressure are stable. He has had no fever, the hepatosplenomegaly has regressed, clubbing has disappeared, the blood count and urinalysis findings are normal, and six blood cultures have been negative. A recent chest roentgenogram shows a decrease in heart size and disappearance of the pulmonary vascular congestion despite some residual aortic insufficiency. COMMENT Infection of a prosthetic valve in our experience [9] and that of other authors [Z, 4, 81 has almost always resulted in the patient s death. VOL. 9, NO. 3, MARCH,

4 MULDER AND JOHNSON Fortunately, the incidence of this complication is low at present because of improved methods of pump sterilization [6], meticulous skin preparation, and protective drapes. The use of antibiotic prophylaxis also may have helped to reduce the overall incidence of endocarditis following pump operations [lo, 121. Several authors have reported sporadic instances in which an infected prosthetic valve has been replaced successfully with a similar device aided by the use of intensive and prolonged antibiotic therapy [3, 51. It is also obvious that replacement is not always feasible or successful and depends to a large measure on whether the infection is confined to the prosthesis or whether burrowing abscesses in the aortic root and base of the heart have occurred. Another approach to the treatment of such patients is the use of a tissue valve to replace the infected prosthesis. It is presumed that a homograft or heterograft is less susceptible to bacterial colonization during the course of an episode of septicemia than is a prosthetic foreign body. The observations of O Brien and co-workers [l 11 tend to support this contention. One of their patients in whom they placed a Starr mitral valve and a heterograft aortic valve died from a ruptured cerebral mycotic aneurysm associated with a staphylococcal septicemia. A large infected thrombus was found attached to the mitral prosthesis, although the aortic heterograft was free of thrombus and infection. An equally serious problem in our patient was the mycotic aneurysm of the ascending aorta, which presumably arose from infection of the previous suture line as described by Campbell [l] and Windsor and Shanahan [13]. Although debridement of the obviously infected aortic wall was necessary, it was equally important to salvage enough ascending aorta to effect primary closure. A prosthetic graft presumably would have been as susceptible to reinfection as a prosthetic valve. An interval of one year since operation with repeatedly negative blood cultures and a benign clinical course is good presumptive evidence that this patient has been cured of his infection, or at least the infection has been effectively suppressed by the moderate doses of gentamicin the patient continues to take. The early occurrence of moderate aortic insufficiency may well be explained by the fact that the aortic homograft was somewhat smaller than the grossly dilated aortic root or that there is a small paravalvular leak. Since the degree of regurgitation has been stable and well tolerated, no further operative intervention is being considered. SUMMARY A patient with congenital aortic-left ventricular tunnel and aortic insufficiency was treated by a reparative procedure. Recurrent aortic 256 THE ANNALS OF THORACIC SURGERY

5 CASE REPORT: Infected Prosthetic Value insufficiency necessitated additional operative procedures on this fistula as well as prosthetic valve replacement on two occasions. Each of these attempts failed because of infection of the prosthetic valves and the aortic root with aneurysm formation. Resection of the infected aneurysm and prosthetic valve with local repair of the aorta and replacement of the valve by a homograft aortic valve has resulted in cure or satisfactory antibiotic suppression of the infection and improvement in valve function. ADDENDUM One and one-half years since the last operative procedure, antibiotics have been discontinued and the fever has not recurred. Aortic insufficiency has not increased, and the patient has returned to full activity. REFERENCES Campbell, G. A. Injuries of the thoracic aorta: Selective review and case report of repair of false aortic aneurysm 13 months after aortic valve surgery. Amer. J. Surg. 105:462, Cohn, L. H., Roberts, W. C., Rockoff, S. D., and Morrow, A. G. Bacterial endocarditis following aortic valve replacement. Circulation 33:209, Ehrenhaft, J. L. Discussion of Kaiser et al. [71. Firor, W. B. Infection following open-heart surgery, with special reference to the role of prophylactic antibiotics. J. Thorac. Cardiovasc. Surg. 53: 371, Herr, R. H., Starr, A., Pierie, W. R., Wood, J. A., and Bigelow, J. C. Aortic valve replacement: A review of six years experience with the ball-valve prosthesis. Ann. Thorac. Surg. 6: 199, Hughes, R. K. A method of improved antisepsis of open-heart surgery. Ann. Thorac. Surg. 2:230, Kaiser, G. C., William, V. L., Thurmann, M., and Hanlon, C. R. Valve re Iacement in cases of aortic insufficiency due to active endocarditis. J. T K orac. Cardiovasc. Surg. 54:491, Kastor, J. A., Akbarian, M., Buckley, M. J., Dinsmore, R. E., Sanders, C. A., Scannel, J. G., and Austen, W. G. Paravalvular leaks and hemolytic anemia following insertion of Starr-Edwards aortic and mitral valves. J. Thorac. Cardiouasc. Surg. 56:279, Mulder, D. G., and Rosenthal, B. P. Late results with Starr valve replacement of the aortic valve. J. Cardiouasc. Surg. (Torino) 9:440, Nelson, R. M., Jenson, C. B., Patterson, C. A., and Sanders, B. C. Effective use of prophylactic antibiotics in open-heart surgery. Arch. Surg. (Chicago) 90:731, O Brien, M. F., Clarebrough, J. K., McDonald, I. G., Hale, G. S., Bray, H. S., and Cade, J. F. Heterograft aortic valve replacement: Initial follow-up studies. Thorax 22:387, Slonim, R., Litwak, R. S., Gadboys, H. L., and Ehrenkranz, N. J. Antibiotic prophylaxis of infection complicating open-heart operations. Antimicrob. Agents Chemother. 3:731, Windsor, H. M., and Shanahan, M. X. Unusual aneurysms of the root of the aorta. J. Thorac. Cardiouasc. Surg. 53:830, VOL. 9, NO. 3, MARCH,