Cardiothoracic Surgery

A case of critical mitral stenosis with severe pulmonary hypertension in a twin pregnancy is presented. On therapeutic evacuation at 15 weeks' gestation the patient became critically unstable, necessitating emergency open heart surgery with mitral valve replacement. (Am J Obstet Gynecol 1998;179:270-2.) Key words: Mitral stenosis, pulmonary hypertension, cardiac surgery Cardiac disease complicates 1% to 4% of all pregnancies in the United States, with rheumatic heart disease being the most common etiology. Mitral stenosis is the rheumatic valvular disease most frequently associated with maternal death. Patients in whom mitral stenosis has led to the development of secondary pulmonary hypertension are advised to avoid pregnancy because they are especially vulnerable to decreases in right heart preload, which may be rapidly fatal. We present a patient with severe pulmonary hypertension who underwent an early second-trimester abortion and in whom acute pulmonary edema developed with near cardiovascular collapse.

Objective: The purpose of this study is to investigate the effects of lung volume reduction surgery on pulmonary compliance, airway flow, and helium lung volumes in an elastase-induced emphysema animal model. Methods: A 15,000-unit bolus of elastase was aerosolized through an endotracheal tube in 14 New Zealand White rabbits to induce emphysema. Stapled lung volume reduction of bilateral upper and middle lobes was performed through a midline sternotomy at 4 weeks after induction of emphysema. Lung functions were measured at baseline before induction of emphysema, preoperatively at 4 weeks, and 1 week postoperatively. Results: Compliance increased after induction of emphysema and decreased in response to lung volume reduction surgery. Functional residual capacity decreased after lung volume reduction surgery in proportion to the amount of excised lung tissue. Expired flows suggested improvement in response to lung volume reduction surgery. Histologic examination confirmed presence of diffuse heterogeneous emphysema in each animal at necropsy. Conclusions: The decreased compliance and increased airway flow after volume reduction surgery in this model parallels findings in human studies and suggests that similar mechanisms of increased elastic recoil and airway support contribute to improvement. (J Thorac Cardiovasc Surg 1998;115:328-35)