Biomedical subjects
Publications and source records attributed to R E Applebaum.
Rupture of the posterior left ventricle is a serious complication following mitral valve replacement. A successful method of repair is illustrated. The causes, other methods of repair, and means to prevent this complication are discussed.
A simplified technique to gain repeated access to the median sternotomy incision is presented. The technique involves the use of a sterile polyester zipper attached to the skin edge. The sternum remains open. Unzipping the zipper allows for repeated relief of cardiac tamponade and viewing of cardiac action. Other advantages include prevention of cardiac compression or kinking of assist device cannulas from sternal closure, ease in changing of dressings, and quick removal of ventricular assist devices without reopening the sternum.
Right ventricular dysfunction frequently occurs in patients undergoing correction of congenital cardiac defects, as well as in other clinical settings. The purpose of the present study was to surgically induce right ventricular dysfunction and then provide circulatory support with a right ventricular assist device. Right ventricular hypertrophy was created in 13 neonatal lambs by pulmonary artery banding. Right ventricular dysfunction was produced in all animals by performing a right ventriculotomy with the animal supported by cardiopulmonary bypass. In four unassisted animals the circulation failed after separation from bypass. Seven experimental animals underwent the insertion of a pneumatically activated ventricular assist device between the proximal pulmonary artery and the right ventricular apex. Periods with the right ventricular assist device on and off in each animal were compared. The right ventricular assist device increased cardiac output from 0.72 +/- 0.15 to 2.24 +/- 0.23 L/min (p less than 0.0002), increased left atrial pressure from 7 +/- 1 to 11 +/- 1 mm Hg (p less than 0.0005), and increased aortic systolic pressure from 53 +/- 9 to 85 +/- 9 mm Hg (p less than 0.0001). Right ventricular assistance significantly reduced the right ventricular end-diastolic pressure from 19 +/- 3 to 12 +/- 1 mm Hg (p less than 0.0001). Pulmonary artery peak pressure distal to the band increased from 27 +/- 3 to 52 +/- 5 mm Hg (p less than 0.0001). The results indicate that right ventricular dysfunction can be produced by a vertical cardiotomy in a hypertrophied right ventricle with persistent outflow tract obstruction. Right ventricular dysfunction can be effectively reversed by a right ventricular assist device, which may prove clinically useful in managing patients with refractory right ventricular failure.
Melorheostosis is a benign, rare congenital disorder of hyperostosis of one or more bones. A case of melorheostosis associated with synchronous left subclavian and axillary artery aneurysms necessitated resection of the aneurysms and replacement with a Gore-Tex interposition graft (W. L. Gore & Associates, Inc., Elkton, Md.) and a reversed saphenous vein graft, respectively. Numerous soft-tissue and vascular anomalies have been noted in patients with melorheostosis, although arterial aneurysms have not been reported previously.
We reviewed the charts of 1,598 patients undergoing valve replacement at the National Institutes of Health, Bethesda, Md, from 1956 through 1981. Retrospective analysis disclosed that 43 patients had prosthetic valve endocarditis (PVE). Twelve patients had early (less than 60 days after operation) and 31 patients had late (greater than 60 days after operation) endocarditis. The cumulative risk was 3% at five years and 5% at ten years. We also calculated the interval risk of PVE. The high risk of early PVE development peaked 15 days after operation. The peak risk was 45 episodes per 100,000 patient days. The risk then declined rapidly and from 150 days to 20 years remained stable at approximately one episode per 100,000 patient days. Nine hundred fifty-two patients had valve replacement with a Starr-Edwards prosthesis and 363 patients had valve replacement with a bioprosthetic valve; there was no significant difference in the risk of PVE in either group. Neither the valve make, position, model, nor the number of valves implanted affected the frequency of PVE or the mortality. Actuarial techniques disclosed the high early risk of PVE, the prolonged risk of PVE up to 150 days after operation, and the low but persistent risk late after operation. There was no significant difference in the risk of PVE in patients with bioprosthetic v mechanical valves.
Mediastinal infection occurred in 29 of 2031 patients (1.4%) who underwent median sternotomy for cardiac operation at the National Heart, Lung and Blood Institute between 1956 and 1981. Factors associated with the development of mediastinitis included postoperative complications such as low cardiac output, respiratory insufficiency, reoperation for bleeding, repeat median sternotomy, and triple valve replacement. Factors that were not significantly associated with the development of mediastinitis included preoperative functional class, preoperative cardiac index, age, sex, weight, or presence of diabetes mellitus. The mortality rate in patients who developed mediastinitis was 52%. Factors associated with death included preoperative functional class III or IV, type of operation, type of organism involved, and the development of pneumonia. The mortality rate was significantly lower (35% versus 73%) in the patients who underwent mediastinal exploration for treatment. There was no difference in survival whether the wound was closed over drainage tubes or packed open. Hospital stay, however, was significantly prolonged in the patients whose wounds were packed open.
Operations for certain congenital cardiac lesions can produce pulmonary regurgitation. Pulmonary regurgitation contributes to right ventricular dysfunction, which may cause early postoperative morbidity and mortality. To ameliorate the problems of pulmonary regurgitation during the early postoperative period, we evaluated a method for its acute control. Complete pulmonary valvectomy was performed utilizing inflow occlusion in eight sheep. A catheter with a 15 ml spherical balloon was positioned in the pulmonary arterial trunk; its inflation and deflation were regulated by an intra-aortic balloon pump unit. Blood flow from the pulmonary arterial trunk and forward and regurgitant fraction were determined from electromagnetic flow transducer recordings. The regurgitant fraction with uncontrolled pulmonary regurgitation was 38% +/- 3% (forward flow = 42 +/- 5 ml/beat and regurgitant flow = 16 +/- 2 ml/beat). Inflation of the balloon during diastole was timed to completely eliminate pulmonary regurgitation. This balloon control of pulmonary regurgitation increased pulmonary arterial diastolic pressure from 12 +/- 1 to 17 +/- 1 mm Hg (p less than 0.0001) and decreased pulmonary arterial systolic pressure from 31 +/- 3 to 27 +/- 1 mm Hg (p = 0.06). Pulmonary arterial pulse pressure decreased from 19 +/- 3 to 9 +/- 1 mm Hg (p less than 0.003). Elimination of pulmonary regurgitation decreased right ventricular stroke volume (25 +/- 3 versus 42 +/- 5 ml/beat, p less than 0.0002) and resulted in a 46% reduction in right ventricular stroke work (5.0 +/- 0.6 versus 9.4 +/- 1.0 gm-m/beat, p less than 0.001) with no change in net forward pulmonary artery flow. Thus, acute pulmonary regurgitation can be controlled and this control improves overall hemodynamic status and decreases right ventricular work.
One thousand five hundred ninety-eight patients who underwent cardiac valve replacement were reviewed. One hundred fifty-two patients (10 percent) required a second valve replacement. The indications for repeat valve replacement were prosthetic valve dysfunction in 53 patients (35 percent), development of a new valvular lesion in 46 patients (30 percent), simple closure of a perivalvular leak in 14 patients (9 percent), change of the valve poppet in 13 patients (8 percent), severe hemolysis or emboli in 21 patients (14 percent), and prosthetic valve endocarditis in 5 patients (3 percent). The mean preoperative New York Health Association functional class improved from 3 to 1.5 in the nonreoperated patients and from 2.9 to 1.8 in patients who underwent a second valve replacement. Similarly, the mean cardiac index improved from 2.5 to 2.9 and from 2.5 to 2.8 in nonreoperated and reoperated patients, respectively. The operative mortality rate was 14 percent in the nonreoperated patients and 16 percent at second operation in the reoperated patients. Using actuarial techniques, the risk of repeat valve replacement was 1 to 4 percent per year. Long-term survival was compared between groups. Using actuarial techniques, the estimated survival rates at 1, 5, and 10 years were 89 percent, 69 percent, and 52 percent, respectively in nonreoperated patients and 87 percent, 60 percent, and 37 percent in reoperated patients. This study has documented the excellent improvement in functional and hemodynamic state after second cardiac valve replacement. The operative mortality and long-term survival rates were similar to those of the nonreoperated patients. Patients having repeat cardiac valve replacement can expect good improvement in length and quality of life.
Right ventricular (RV) failure frequently occurs in patients undergoing correction of congenital cardiac defects, as well as in other clinical settings. RV hypertrophy was created in 10 neonatal lambs by pulmonary artery (PA) banding. Twelve months later RV hypertrophy was present (RV weight/body weight = 2.71 +/- 0.31 gm/kg); RV systolic pressures were elevated (65 +/- 9 mm Hg) and the average gradient across the PA band was 38 +/- 9 mm Hg. RV failure was produced in all animals by performing a right ventriculotomy. Four unassisted (control) animals died shortly after separation from bypass. Six experimental animals underwent pulmonary artery balloon counterpulsation (PABCP). A Dacron graft anastomosed to the proximal PA served as a reservoir for a 40 ml intra-aortic balloon pump system. PABCP effectively reversed RV failure, low cardiac output, and systemic arterial hypotension. Periods with PABCP on and off in each animal were compared. PABCP increased cardiac output from 1.45 +/- 0.16 to 2.03 +/- 0.13 L/min (p less than 0.0001) and increased aortic systolic pressure from 78 +/- 7 to 99 +/- 6 mm Hg (p less than 0.0004). PABCP produced a significant reduction in RV peak systolic pressure from 56 +/- 5 to 41 +/- 3 mm Hg (p less than 0.0001). PA peak pressure distal to the band increased from 31 +/- 2 to 40 +/- 1 mm Hg (p less than 0.0001). Right atrial pressure decreased from 14 +/- 1 to 11 +/- 1 mm Hg (p less than 0.0001) with PABCP, and RV end-diastolic pressure fell from 15 +/- 1 to 11 +/- 1 mm Hg (p less than 0.0001). RV stroke work index increased 49% from 0.081 +/- 0.011 to 0.121 +/- 0.017 gm X m/kg/beat (p less than 0.01), and RV systolic pressure time index decreased 38% from 1140 +/- 79 to 710 +/- 65 mm Hg sec/min (p less than 0.0001). Thus PABCP in the presence of RV dysfunction can produce substantial improvement in RV function and in overall cardiac function and may prove clinically useful in managing patients in refractory RV failure.