Effect of prazosin treatment on the cardiac sarcolemmal ATPase in failing heart due to mitral insufficiency in dogs

Prazosin has been used in the treatment of congestive heart failure. It is, however, not known whether prazosin gives only haemodynamic benefit or if it also produces a decrease in the cardiac sarcolemmal Na+-K+-ATPase which has been reported to be increased in the failing heart. The present investigation deals with the effect of 3 months of prazosin treatment in dogs with 3 months of induced mitral insufficiency (MI) on the sarcolemmal Na+-K+-ATPase activity. The dogs were divided into four groups each comprising of five dogs. A--normal; B--3 months of MI; C--6 months of MI; D--3 months of prazosin treatment after 3 months of MI. Three months of MI produced a decrease in the dp/dt and an increase in the end-diastolic pressure of left ventricle but no change in the index of left ventricular contractility and cardiac index. Also there was no change in the sarcolemmal Na+-K+-ATPase. There was a significant decrease in the index of left ventricular contractility and cardiac index and an increase in the LVEDP associated with a significant increase in the left ventricular sarcolemmal Na+-K+-ATPase at 6 months of MI. Sarcolemmal Mg2+-ATPase of both ventricles increased after 6 months of MI the significance of which is not known as yet. There was no change in the sarcolemmal Na+-K+-ATPase of the nonfailing right ventricle. Prazosin treatment prevented the deterioration of the left ventricular contractility and function and also prevented the increase in the sarcolemmal Na+-K+-ATPase observed in failing heart.(ABSTRACT TRUNCATED AT 250 WORDS)     

Myocardial enzyme activities in patients with mitral regurgitation or mitral stenosis

To determine the adaption of myocardial metabolism in mitral regurgitation and mitral stenosis, human papillary muscles obtained during open heart surgery were analysed to measure selective enzyme activities in energy metabolism. All enzyme activities were expressed per unit dry weight muscle, per unit alkali soluble protein, and per unit total creatine and the different results compared. The activities of enzymes concerned with mitochondrial energy production and energy transfer (namely, citrate synthase and mitochondrial creatine kinase) tended to be higher in papillary muscles from hearts with mitral regurgitation than in those with mitral stenosis. The activities of enzymes concerned with cytoplasmic energy production (creatine kinase MM, lactate dehydrogenase, and phosphofructokinase) did not show statistically significant differences between mitral regurgitation and mitral stenosis. The ratio of creatine kinase MB activity to total creatine content showed the greatest difference when papillary muscles from patients with mitral regurgitation and mitral stenosis were compared (31% higher in mitral regurgitation; p less than 0.001). The specific function of creatine kinase MB, which is located in cytoplasm, is not well defined. Creatine kinase MB activity increases with extreme endurance training of human skeletal muscle. Thus the higher creatine kinase MB activity in papillary muscle of mitral regurgitation may represent an adaptation to increased physical demand.     

Mitral insufficiency with congenital double-orifice mitral valve in an elderly patient.

We describe the case of a 79-year-old woman with mitral insufficiency and a double-orifice mitral valve (DOMV), discovered by echocardiography. Transthoracic echocardiography showed two insufficiency jets. Transesophageal echocardiography revealed a DOMV. Each orifice was provided with a subvalvular apparatus. No associated congenital abnormalities were present. Our case demonstrates that even in elderly patients with a double regurgitant jet, DOMV should be suspected and assessed by transesophageal echocardiography.     

Dynamic echocardiography in mitral insufficiency

Mitral insufficiency can have a dynamic character, correlating to an intermittent increase in the area of the regurgitant orifice and the regurgitant volume. Among the various stress methods, echocardiography during effort on a bicycle in the semisitting position appears to be the technique of choice for evaluating this dynamic character. Thanks to the improvement of the Doppler signal quality, quantification of the regurgitant volume variations can be obtained in a reproducible manner at rest and during effort by applying the "PISA" method.     

Mitral valve repair for significant mitral insufficiency.

There has been skepticism since the early days of open heart surgery that good long-term or even short-term results were possible with repair of pure mitral insufficiency. The authors report 145 patients in whom a markedly insufficient mitral valve was repaired 6 months to 17 years previously and another 55 patients in whom repair of the insufficient mitral valve was performed along with myocardial revascularization from 6 months to 7 years previously. Comparative data with other published work reveals superior results with repair than with replacement with Starr-Edwards and Hancock glutaraldehyde-treated porcine valves and with far less emboli. Conservatism is urged in operating upon patients with mitral insufficiency. Repair of the valve rather than replacement is stressed for those patients requiring surgery.     

Long-term prognosis after mitral annuloplasty for acquired mitral insufficiency. Clinical evaluation

Twenty-nine patients with isolated (18) or predominant (11) mitral insufficiency were treated by mitral annuloplasty. This post-operative follow-up study, lasting from 3 to 5(1/2) years (average 48 months), resulted in the following conclusions. The clinical, radiological, and electrocardiographic conditions usually followed a parallel course. Initial good results were maintained for up to 4 years in only 16 patients. Subsequent deterioration was related to progression to mitral stenosis (2 patients), recurrence of severe mitral insufficiency (13 patients), occurrence (5 patients) or recurrence (8 patients) of tricuspid insufficiency. Poor results were more often observed in the eldest patients, with conspicous pre-operative cardiac enlargement, atrial fibrillation, and long-standing cardiac failure. The indications for annuloplasty are reduced and apply primarily to mitral insufficiency without obvious cardiac enlargement, with normal sinus rhythm, and with short-standing congestive cardiac failure.