The prognostic value of preoperative echocardiographic data was assessed in 32 patients who underwent aortic valve replacement for chronic aortic regurgitation. All patients had preoperative studies and were followed up prospectively for 1 to 6 years after surgery. Postoperatively, 25 patients (Group A) achieved a normal left ventricular end-diastolic dimension and a significant regression of myocardial hypertrophy; 7 patients (Group B) had persistent left ventricular enlargement. During the follow-up period, the patients in Group A had fewer symptoms and used fewer medications than those in Group B. Moreover, survival at 4 years appeared to be better in Group A (96%) than in Group B (71%); two patients in Group B died with congestive heart failure; there were no such deaths in Group A. Preoperatively, a left ventricular dimension at end-diastole (DED) larger than 3.8 cm/m2 body surface area, a dimension at end-systole (DES) greater than 2.6 cm/m2 body surface area, an end-diastolic radius/wall thickness ratio (R/Th) greater than 3.8 or a product of R/Th and left ventricular systolic pressure (P X R/Th) exceeding 600 are predictive of a Group B result. If end-systolic dimension is greater than 2.6 and P X R/Th is greater than 600, all Group B patients can be identified; all but one patient in Group A had an end-systolic dimension less than 2.6 and P X R/Th less than 600. It is concluded that patients with chronic aortic regurgitation who are at risk of persistent postoperative left ventricular enlargement (with associated cardiac symptoms and reduced survival) can be identified by preoperative echocardiography.
Three adults with osteogenesis imperfecta and associated cardiovascular lesions are reported. Two presented with aortic insufficiency due to dilatation of the aortic root for which none of the usual causes is apparent. The third patient was found to have lesions involving pulmonary, aortic, and mitral valves in addition to microscopic changes in the pulmonary artery and aorta. It is suggested that in osteogenesis imperfecta, as in other heritable disorders of connective tissue, cardiovascular defects may become apparent after the passage of time and play a dominant role in the natural history of the disease process.
Potassium has been rapidly removed from the circulating blood of dogs in 22 experiments in which other extracellular electrolytes were maintained constant. In these experiments potassium extraction occurred in an acute phase accompanied by a reduction in serum level and a second phase of continued extraction with little change in the extracellular concentration. In the first phase the P wave increased markedly in amplitude and width. The A-V conduction time became prolonged. The QRS complex widened, the T wave became broadened and rounded, and the S-T segment de-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.