Pathology of mitral valve stenosis and pure mitral regurgitation--Part I

This two-part article examines the histologic and morphologic basis for stenotic and purely regurgitant mitral valves. In Part I, conditions producing mitral valve stenosis are reviewed. In over 99% of stenotic mitral valves, the etiology is rheumatic disease. Other rare causes of mitral stenosis include congenital malformed valves, active infective endocarditis, massive annular calcium, and metabolic or enzymatic abnormalities. In Part II, conditions producing pure mitral regurgitation will be discussed. In contrast to the few causes of mitral stenosis, the causes of pure (no element of stenosis) mitral regurgitation are multiple. Some of the conditions producing pure regurgitation include floppy mitral valves, infective endocarditis, papillary muscle dysfunction, rheumatic disease, and ruptured chordae tendinae.     

Causes of recurrences of mitral stenosis

The authors present an analysis of the late results of closed mitral commissurotomy in 364 patients (maximum terms of observation--17 years). Main causes of recurrent mitral stenosis were recognized: activation of a rheumatic process (50%), nonspecific scarring processes (27%), inadequate commissurotomies (11.1%) and others (11.1%). The routine antirheumatic therapy (bicillin+salicylates) was found to be ineffective in prophylaxis against mitral restenoses. Recurrent mitral stenosis proved to occur more frequently in patients operated upon in young age (under 30).     

Propranolol in mitral stenosis during sinus rhythm

Patients with early symptomatic mitral stenosis usually suffer from pulmonary congestion on the basis of left atrial and pulmonary venous hypertension. They are often in sinus rhythm, and cardiac output is usually well maintained. Symptoms occur most often when heart rate, cardiac output, or both are increased. In this study, intravenous propranolol administered to patients with pure mitral stenosis in sinus rhythm resulted in significant reductions in mitral diastolic gradient (-7.1 mm. Hg +/- 1.6 SED), mean pulmonary wedge pressure (--6.9 mm. Hg +/- 1.2) and mean pulmonary artery pressures (--9.0 mm. Hg +/- 1.2). This was due to simultaneous reduction of heart rate (--13.0 beats/minute +/- 2.6 and cardiac output (--0.5 L./minute +/- 0.2). A small associated reduction of left ventricular systolic pressure (--5.1 mm. Hg +/- 2.6) was not accompanied by adverse clinical effects. A potential role for propranolol in medical management of pure mitral stenosis in the presence of sinus rhythm is suggested.     

Mitral annulus size in isolated mitral stenosis

M-mode and two-dimensional echocardiographic images were obtained using the planimeter method in the short axis view and calculated by Doppler-derived pressure half-time in 24 patients with mitral stenosis before and after surgical commissurotomy and posterior annuloplasty. The diameter of the mitral valve annulus was measured in the standard long axis view and in the apical four-chamber view using two-dimensional echocardiography. Preoperatively, the mitral annulus was dilated in all patients as a consequence of left atrial dilation. This could be one of the factors causing residual regurgitation after surgical mitral commissurotomy. However, more data are needed to demonstrate that annuloplasty can prevent the development of mitral regurgitation after surgery.     

Coronary atherosclerosis in subjects with mitral stenosis

The coronary arteries were examined in 60 specimens from patients with mitral stenosis. In three, localized obstruction was nonatherosclerotic in nature (in one, arterial dysplasia; in two, embolic). In 18 of the remaining 57 cases (31.5%), significantly obstructive atherosclerosis in one or more segments of the coronary arterial system was found. This represented 46% of the males and 27% of the females. The incidence of involvement of three or more arteries by significantly obstructive atherosclerosis was 39%, while in a cited series of subjects with angina pectoris three or more vessels were involved in 79% of the cases. It may be concluded that, on the average, the distribution of lesions in patients with mitral stenosis and significant coronary atherosclerosis is less wide than in subjects with clinical coronary disease.     

Bronchial hyperresponsiveness before and after percutaneous transluminal mitral commissurotomy in patients with mitral stenosis

To study the effects of percutaneous transluminal mitral commissurotomy (PTMC) on bronchial responsiveness to inhaled methacholine in patients with mitral valve stenosis (MS), methacholine inhalation tests and pulmonary function tests were done in 10 patients with MS before and one week after PTMC. The mean log cumulative dose producing a 35% decrease in respiratory conductance (PD35Grs) was significantly higher after PTMC in nine patients in whom PTMC was successful (p < 0.05). There were no significant changes in the results of pulmonary function tests after PTMC. One patient had severe mitral regurgitation after PTMC, and a decrease in PD35Grs. Six of the other nine patients in whom PTMC was successful continued to be hyperresponsive to inhaled methacholine. These data show that bronchial hyperresponsiveness in patients with MS is less severe after PTMC, concomitant with the relief of pulmonary congestion, and they suggest that the remaining bronchial hyperresponsiveness is responsible for peripheral airway narrowing with organic remodeling.     

Percutaneous mitral balloon valvotomy in a patient with coexistent mitral stenosis and hypertrophic cardiomyopathy

A patient with coexistent mitral stenosis and hypertrophic cardiomyopathy is described, in whom symptoms related to impaired left ventricular diastolic filling improved after successful percutaneous mitral balloon valvotomy.     

Immediate and follow up results of Inoue balloon mitral valvotomy in juvenile rheumatic mitral stenosis

1. One of the main obstacles to the reliable detection of human papillomavirus in cervical intraepithelial neoplasia is that a minute quantity of infected tissue is often all that is available. 2. In this work, proteinase K-phenol-chloroform-treated sections of frozen cervical biopsies were split in two. Half of the material was precipitated by ethanol in the presence of glycogen, and in the remaining half glycogen was absent. 3. On average a 15-fold increase in total DNA yield was obtained with glycogen. As a result, in 63 cases analysed by PCR for human papillomavirus type 16, we were able to detect nearly 20% more positive samples when glycogen was used. 4. The implications of the improved accuracy of diagnosis are that women requiring a closer follow-up can be identified, and conversely rescreening intervals can be extended for those testing negative for oncogenic human papillomavirus types with more confidence than in the past.     

Percutaneous transvenous balloon dilatation of mitral valve stenosis

In this study, 42 consecutive symptomatic patients (median age 60 (30-78) years, 86% females) with mitral valve stenosis (57% had severely deformed and/or calcified mitral valves) were treated with (Inoue) balloon dilatation during the period August 1989-June 1994. Mitral valve area and cardiac output increased by 67 and 25%, whereas the transmital gradient as well as pulmonary artery pressure fell by 45% and 21%, respectively, after the dilatation. Follow-up at a mean of 16 (1-46) months revealed a total mortality of 12% (cardiac mortality of 7%). Five patients developed significant' mitral regurgitation after the treatment and four of these had subacute mitral valve replacement. A further four patients received an artificial valve during the follow-up period. During the follow-up period the increase in valve area remained unchanged, and accordingly 97% of the patients were in New York Heart Association functional class I-II. Balloon dilatation was an acceptable treatment in the described elderly population with significant mitral stenosis and deformed valves.     

Mitral valve area in combined mitral stenosis and regurgitation

Eight patients with mixed mitral stenosis and regurgitation underwent hemodynamic and angiographic study prior to mitral valve replacement. The stenotic orifice of the mitral valve was calculated employing the total left ventricular stroke volume by cineangiography as the numerator of the Gorlin Formula. Excellent agreement with the measured orifice of the mitral valve was obtained using a value of 37.9 (0.85 X 44.5) for the constant in the Gorlin formula as recommended by Cohen and Gorlin. Recalculation of this constant independently by our data yielded a value that was almost identical. Regurgitant flows and orifice sizes were calculated for each patient using the same constant as for calculation of the stenotic orifices.     

Newer advances in the diagnosis and treatment of mitral stenosis

There have been significant changes in presentation, diagnosis, and therapy of patients with mitral stenosis. Both the prevalence of mitral stenosis, as well as the type of patient now with mitral stenosis, have changed significantly over the past few decades. In patients with mitral stenosis two-dimensional and Doppler echocardiography have become the diagnostic modalities of choice. The advent of percutaneous mitral balloon valvotomy now provides a nonsurgical approach for the treatment of selected patients with mitral stenosis.