Aortic valve implantation techniques--should they be any different for the pulmonary autograft and the aortic homograft?
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Biomedical subjects
Publications and source records attributed to M F O'Brien.
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Patients (n = 195) undergoing aortic valve replacement (n = 209) for native or prosthetic valve endocarditis were studied to determine risk factors for death and recurrent endocarditis and also to determine the valve type least likely to be associated with recurrent endocarditis. Ten-year survival was 60%, the highest risk of dying occurring within the first 3 postoperative months. Risk factors for death in this early phase included increased urea concentration, higher New York Heart Association functional class, prosthetic valve endocarditis, infection status (lower in patients with healed endocarditis), longer duration of cardiopulmonary bypass, and nonuse of an allograft valve. In the late phase (beyond 3 months), risk factors included age at operation and Staphylococcus aureus infection (only in New York Heart Association functional class V). Ten years after aortic valve replacement, 79% of valves were free of recurrent endocarditis. The highest risk of recurrence was in the first 4 months. Longer duration of cardiopulmonary bypass was a weak risk factor for recurrent endocarditis in the early phase, and in the late phase risk factors were S. aureus infection (only in New York Heart Association functional classes III, IV, and V) and the use of now discontinued biologic valves. Allograft aortic valve replacement was shown to be associated with a low and constant risk of recurrent endocarditis, whereas other valve types were associated with a high early risk. The allograft valve should be the preferred replacement device for aortic root infection.
Aortic valve replacement with or without concomitant procedures was performed using an allograft aortic valve in 534 patients. From December 1969 to May 1975 (group I), a 4 degrees C stored valve was used (124 patients) and from June 1975 to July 1990 (group II), a cryopreserved valve (410 patients) was used. The 30-day mortality was 8.9% (confidence limits [CL] 6.2%-12.3%) for group I and 2.7% (CL 1.9%-3.8%) for group II. Actuarial patient survival including early hospital mortality at 14 years was 57% for group I and 71% for group II (p = 0.014). Actuarial freedom from thromboembolism for all patients (n = 534) was 94% at 14 years, and for patients who underwent isolated aortic valve replacement with or without coronary artery bypass graft (n = 457) was 97% at 14 years (p = 0.017). Actuarial freedom from allograft valve endocarditis at 14 years was 92% in group I and 94% in group II (p = 0.36). The actuarial freedom from moderate or severe allograft valve incompetence at 14 years was 50% (group I) and 78% (group II) (p = 0.27). Reoperation was undertaken for endocarditis, leaflet structural deterioration (SD), or technical reasons. The actuarial freedom from reoperation (all causes) at 14 years was 63% (group I) and 86% (group II) (p = 0.39). Reoperation for SD occurred in 34 patients in group I and three patients in group II. The actuarial freedom from reoperation for SD at 14 years was 67% (group I) and 95% (group II) (p = 0.001). To reflect a more accurate depiction of the prevalence of SD, patients were analyzed according to the development of "assumed structural deterioration" (at reoperation, at death with moderate or severe allograft valve incompetence and macroscopic valve deterioration on autopsy, and in the presence of moderate or severe allograft valve incompetence in patients not undergoing reoperation). The actuarial freedom from "assumed structural deterioration" at 14 years was 51% (group I) and 85% (group II) (p = 0.000003). The long-term results confirm the low incidence of thromboembolism and endocarditis regardless of the method of preservation and demonstrate the overall acceptable performance of the viable cryopreserved allograft valve and its superiority over the 4 degrees C stored valve.
Allograft replacement of the aortic root is a logical extension of subcoronary allograft aortic valve replacement. The aortic root can be replaced by a cryopreserved allograft aortic root using an inclusion technique employing a continuous Prolene suture for each of the suture lines. This technique provides an expeditious operation and hemostatic suture lines.
The geometry and degree of symmetry of the diseased aortic root and valve dictate the technical method of implantation of the allograft aortic valve. Five methods are available that are suitable for the full range of aortic root disease: the small aortic root with a valve annulus diameter less than 21 mm, the common aortic valve lesions (valve annulus diameter, 21 to 29 mm), the aneurysmal noncoronary sinus, the moderately large annulus (valve annulus diameter greater than 30 mm), and the aneurysmal aortic root and dilated annulus. Implantation methods include the subcoronary technique, miniroot inclusion technique, and aortic root replacement. Technical variations such as valve inversion during implantation, valve rotation, and continuous or interrupted suture methods are important in certain techniques. The allograft aortic valve is a versatile device that can be used in the surgical management of the full range of aortic valve and aortic root pathology.
From June 1975 to December 1987, 231 patients underwent aortic valve replacement with a viable cryopreserved allograft aortic valve. Throughout this era, a uniform procurement and preservation was used to maintain leaflet fibroblast viability. The allograft valve was obtained from coroner's autopsies within 24 hours of death, and more recently from organ donors, incubated for 24 hours in low dose antibiotic solution followed immediately by cryopreservation (mean time interval 39 hours after donor death). Viability was ensured by monitoring glucose utilization of the aortic and pulmonary valves and by demonstrating fibroblast growth in tissue cultured from the pulmonary valve. A uniform protocol for valve preparation was used during the entire experience. Nine allograft aortic valves have been obtained by eight reoperations (two were for leaflet degeneration) and one autopsy. The time intervals from implantation to explantation were 2 months, 10 months, 20 months, 22 months, 2.2 years, 5 years, 8.3 years, 9.2 years, and 10.8 years. Histologic examination of the leaflet tissue disclosed a variable degree of cellularity, ranging from a highly cellular matrix (9.2 years) to minimal cellularity (20 months). Within the same valve (10 months), one leaflet was completely acellular with a moderate degree of cellularity in the other two leaflets. The competent valve recovered at autopsy (8.2 years) was essentially acellular. Fibroblasts could consistently be cultured from leaflets in which viable cells were seen histologically. Chromosomal analysis of cultured cells from a valve leaflet (9.2 years) that was implanted with a donor and recipient sex mismatch demonstrated persistence of donor cells.(ABSTRACT TRUNCATED AT 250 WORDS)
From December 1969 to May 1975, 124 patients underwent aortic valve replacement with an allograft aortic valve sterilized by incubation in a low dose antibiotic solution and stored by refrigeration at 4 degrees C (4 degrees C stored valve group). From June 1975 to December 1987, 231 patients received an allograft aortic valve, sterilized by the same low dose antibiotic solution, but stored by cryopreservation in liquid nitrogen at -196 degrees C (cryopreserved valve group). The 4 degrees C stored valves were essentially nonviable, whereas the cryopreserved valves were viable at implantation. Of the 355 aortic valve replacements, associated procedures were performed in 127 patients. The 30-day mortality was 8.9% (confidence limits [C.L.] 6.2% ... 12.3%) (4 degrees C stored) and 4.8% (C.L. 3.3% ... 6.7%) (cryopreserved). Actuarial survival was similar in both groups, being 71% and 67% at 10 years in the 4 degrees C stored and cryopreserved valve groups, respectively (P = .18). The probability of a thromboembolic event was low, but appeared higher in the 4 degrees C stored valve group (actuarial freedom at 10 years, 90%) than the cryopreserved valve group (actuarial freedom at 10 years, 98%) (P = .01) probably related to associated mitral valve surgery. The actuarial freedom from allograft valve endocarditis at 10 years was 94% and 95% for the 4 degrees C stored and cryopreserved valve groups, respectively (P = .23). Reoperation was undertaken in 34 patients in the 4 degrees C stored group and 12 patients in the cryopreserved valve group for leaflet degeneration, endocarditis, or technical reasons.(ABSTRACT TRUNCATED AT 250 WORDS)
One hundred and twenty-four patients underwent aortic valve replacement with a nonviable 4 degrees C refrigerated aortic allograft valve. One hundred and eighty-four patients underwent aortic valve replacement with a viable cryopreserved aortic allograft valve in a later era. The longest follow-up was 16 years for the group with the nonviable valve and 11 years for the group with the viable valves. Within this time frame, reoperation was required in 23 patients with nonviable valves for leaflet perforation or rupture whereas no patients in the group with viable valves developed this complication (p less than 0.0001). The prevalence of endocarditis and thromboembolism was very low in both groups. Viability of leaflet tissue is associated with an important improvement in durability over nonviable allograft valves. Consequently, long-term follow-up results of allograft valves might be best expressed in terms of viability. The current evidence suggests that the viable cells are donor in origin. The viable cryopreserved aortic allograft valve offers significant advantages over current nonviable allograft valves, mechanical valves, and bioprostheses.
We examined the long-term clinical function and fate of allograft aortic valves, preserved by two differing methods, for aortic valve replacement: (1) fresh allografts stored at 4 degrees C refrigeration (group I) and (2) viable allografts cryopreserved in liquid nitrogen at -196 degrees C (group II). A total of 316 aortic valve replacement operations were performed, 124 in group I (December 1969 to May 1975) and 192 in group II (June 1975 to December 1986). Concomitant surgical procedures (eg, coronary artery bypass grafting and mitral valve replacement) were necessary in 120 operations. The overall immediate 30 day mortality was 6.0% (confident limits 4.6% to 7.7%), and the survival rates were 83% at 4 years and 60% at 15 years. Endocarditis and technical factors concerning reoperation showed no difference between the two groups according to parametric estimates and hazard function analyses. However, there was a marked difference in reoperation for valve degeneration: 23 patients in group I and 0 patients in group II. The freedom from reoperation for valve degeneration at 10 years was 89% for group I and 100% for group II, and at 15 years it was 59% for group I. The hazard function for group I reflected the late rising risk of degeneration. The freedom from thromboembolism of both groups (aortic valve replacement with or without bypass grafting) was 97% at 10 years and 96% at 15 years. Group II explanted valves (operation for technical malalignment reasons) has consistently shown evidence of persisting viability on tissue culture, on metabolic studies, and on histologic appearances. Chromosomal studies have shown the donor origin of these cells. The superior results with the cryopreserved valve is considered to be due to persisting viability, which appears to be the key to durability.
A 45-year-old patient with cardiac involvement from the idiopathic hypereosinophilic syndrome suffered from severe congestive cardiac failure with progressive deterioration despite intensive medical therapy. Investigations indicated bilateral ventricular infiltration with endomyocardial fibrosis which had caused severe haemodynamic restriction and bilateral atrioventricular valvular incompetence. Extensive surgery, which included bilateral ventricular endomyomectomy and mitral and tricuspid valve replacements, resulted in a significant improvement for six months.
The clinical, echocardiographic, hemodynamic, angiographic and pathologic features of five patients who had right heart thrombus are presented and their management is discussed. Two modes of presentation were recognized. In four patients, right heart thrombus complicated peripheral venous thrombosis and was associated with major pulmonary thromboembolism and right heart obstruction. In the fifth, it complicated myocarditis with heart failure and appeared to cause right heart obstruction. Two-dimensional echocardiography was diagnostic of right heart thrombus in four patients and showed evidence of right heart dysfunction in those with major pulmonary thromboembolism. The diagnosis was confirmed at surgery in three patients and at autopsy in one. Three patients successfully underwent surgical removal of the thrombus followed by anticoagulation. One patient was treated successfully with anticoagulation alone. The only death occurred in the patient with myocarditis.
In a young man presenting with an episode of syncope and ventricular tachycardia but with no chest pain the right coronary artery was found to originate from the left aortic sinus of Valsalva. After a coronary artery bypass graft he was able to return to full activity.
Coronary artery bypass surgery has a survival rate of 98 to 99 per cent. Recent statistics demonstrate that it offers an increased life span and long term relief (or improvement) of symptoms; the efficacy of surgery is proven, especially in those with left main and multiple coronary vessel disease. For most patients the indications for referral are clear; for some they are not. Risk factors (before and after surgery) must be reduced.
Eleven patients with aortic rupture secondary to non-penetrating thoracic trauma, recent in four patients and of longer standing in seven, have been operated upon. Every patient with an acute injury had a widened mediastinum in the chest skiagram. The diagnosis of traumatic rupture was made by aortography in each case. The operative procedure involved cardiopulmonary bypass, left heart bypass or aorta to aorta bypass shunt. There was one postoperative death. It is recommended that in the acute stage a rupture of the aorta secondary to trauma should be repaired as soon as possible, while ruptures of long standing should be electively repaired.
A method for determining the viability of homograft valves has been developed based on sequential measurements of glucose and pH levels of the culture medium in which cardiac valves have been maintained for short periods at 37 degrees C. Viable valves, as determined by tissue culture, showed a characteristic pattern of glucose utilization and pH reduction that was absent in nonviable valves. Upon explantation of valve leaflet fragments into tissue culture, only fragments from valves that metabolized glucose produced viable fibroblast cultures. The method reported here is rapid, requires no specialized equipment, is nondestructive, and can directly determine the viability of the valve homograft within 24 to 48 hours.
Thirteen patients with proven Q fever endocarditis and three additional patients with probable endocarditis are reviewed. The most helpful diagnostic test is the demonstration of a high complement fixing antibody titre to Phase 1 antigen of Coxiella burneti. The macroscopic pathology of the aortic valve is described and includes aneurysmal pockets in the aortic wall and valve annulus which are demonstrable angiographically. Evidence is presented that the infection may be controlled by prolonged tetracycline therapy and that this is accompanied by a falling antibody titre to Phase 1 antigen. Valve replacement is undertaken only for symptomatic and hemodynamic indications. The combined tetracycline therapy and valve replacement have produced a fall in titres with eradication of infection and palliation of the cardiac disability in all patients followed for long periods.
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