Faculty Bibliography

BACKGROUND: Lung volume reduction surgery has shown early promise as a palliative therapy in severe emphysema. Selection of potential candidates has been based on certain functional and anatomic criteria, and a variety of operative contraindications have been proposed. METHODS: Over 15 months, we performed lung volume reduction surgery in 85 patients selected on the basis of severe hyperinflation with air trapping, diaphragmatic dysfunction, and disease heterogeneity. Patients were not excluded on the basis of severe hypercapnia, steroid dependence, profound pulmonary dysfunction, or inability to complete preoperative rehabilitation. RESULTS: We observed significant improvements in pulmonary function, exercise capacity, and dyspnea, with an acceptable 30-day perioperative mortality of 7% and actuarial survival of 90% and 83% at 6 and 12 months, respectively. In each "high-risk" group, perioperative mortality, actuarial survival to 1 year, and functional results were equivalent, and in some cases superior, to those in the corresponding "low-risk" patients. CONCLUSIONS: Severe hypercapnia, steroid dependence, profound pulmonary dysfunction, and inability to complete preoperative rehabilitation do not preclude successful lung volume reduction surgery and should not be regarded as absolute exclusionary criteria.

Percutaneous stents are used in vascular applications in conjunction with angioplasty and in combination with graft material for repair of abdominal aneurysms. The authors have designed a collapsible bioprosthetic aortic valve for placement by a transluminal catheter technique. This trileaflet stent valve is composed of stainless steel and bovine pericardium. Stent valves, 23 and 29 mm, were tested in a pulse duplicator system with rigid rings from 21 to 31 mm in 2 mm increments. At a mean flow of 3.1 L/min (+/-0.7), normal systemic aortic pressure was generated with a transvalvular gradient of 14.9 +/- 7 mmHg (mean +/- SD). Regurgitation fraction ranged from 10 to 18% (mean 13.8 +/- 3%) in the best ring size. Valves with the best hemodynamic profile were used for implantation in three 70 kg pigs in an open chest model. The valve was collapsed in a 24 Fr catheter designed to allow slow, controlled release. After resection of the native leaflets, the new valve was placed in the subcoronary position. No additional sutures were used for securing the valve. Two animals were successfully weaned from cardiopulmonary bypass and maintained systemic pressures of 100/45 (+/-10) and 116/70 (+/-15) mmHg, respectively. Intraoperative color echocardiography revealed minimal regurgitation, central flow, full apposition of all leaflets, and no interference with coronary blood flow. Both animals were sacrificed after being off bypass for 2 hr. Postmortem examination revealed the valves to be securely anchored. The third animal was weaned from cardiopulmonary bypass but developed refractory ventricular fibrillation because of valve dislodgment due to structural failure. Although long term survival data are needed, development of a hemodynamically acceptable prosthetic aortic valve for transluminal placement is feasible.