The spectrum of mitral regurgitation in idiopathic mitral valve prolapse: a color Doppler study

Haemodynamic determinants of the mitral valve closure sound: a finite element study

Automatic acoustic classification and diagnosis of mitral valve disease remain outstanding biomedical problems. Although considerable attention has been given to the evolution of signal processing techniques, the mechanics of the first heart sound generation has been largely overlooked. In this study, the haemodynamic determinants of the first heart sound were examined in a computational model. Specifically, the relationship of the transvalvular pressure and its maximum derivative to the time-frequency content of the acoustic pressure was examined. To model the transient vibrations of the mitral valve apparatus bathed in a blood medium, a dynamic, non-linear, fluid-coupled finite element model of the mitral valve leaflets and chordae tendinae was constructed. It was found that the root mean squared (RMS) acoustic pressure varied linearly (r2= 0.99) from 0.010 to 0.259 mmHg, following an increase in maximum dP/dt from 415 to 12470 mm Hg s(-1). Over that same range, peak frequency varied non-linearly from 59.6 to 88.1 Hz. An increase in left-ventricular pressure at coaptation from 22.5 to 58.5mm Hg resulted in a linear (r2= 0.91) rise in RMS acoustic pressure from 0.017 to 1.41mm Hg. This rise in transmitral pressure was accompanied by a non-linear rise in peak frequency from 63.5 to 74.1 Hz. The relationship between the transvalvular pressure and its derivative and the time-frequency content of the first heart sound has been examined comprehensively in a computational model for the first time. Results suggest that classification schemes should embed both of these variables for more accurate classification.

Mitral regurgitation reduces the risk of stroke in patients with nonrheumatic atrial fibrillation

BACKGROUND

Significant mitral regurgitation (MR) is protective against left atrial (LA) spontaneous echo contrast formation that is associated with an increased thromboembolic risk. However, the effects of MR on the risk of stroke in patients with nonrheumatic atrial fibrillation (AF) have been unknown. We studied whether or not MR was associated with a decreased risk of stroke in patients with nonrheumatic AF.

METHODS

We performed an observational analysis of retrospectively collected data on 290 patients with nonrheumatic AF. Left atrial diameter (LAD) and the degree of MR were estimated by transthoracic echocardiography. Risk factors for stroke were assessed by univariate and multivariate analyses. The mean follow-up was 7.4 years.

RESULTS

Among these patients, 68 had a stroke during the follow-up (rate of stroke per year of follow-up 3.2%). In 95 patients with LAD of > or =48 mm, the incidence of stroke (9%) in the severe MR group (moderate or severe, n=43) was significantly lower than that (25%) of the mild MR group (none, trivial, or mild; n=52) (chi-square=3.95, p=0.047). The relative risk of stroke for increase in MR from mild to severe groups, for every 10 mm increment in LA size, for sex, and for every increase of 10 years of age was 0.45 (95% CI, 0.20 to 0.97), 1.06 (95% CI, 0.75 to 1.49), 0.98 (95% CI, 0.55 to 1.72), and 1.33 (95% CI, 1.04 to 1.71), respectively.

CONCLUSIONS

In patients with nonrheumatic AF, age was an independent predictor of an increased risk of stroke, and MR may be protective against stroke, especially in those patients with LA enlargement.

Relationship between severity of mitral regurgitation and prognosis of mitral valve prolapse: echocardiographic follow-up study

We investigated the relation between the severity of mitral regurgitation and the development of complications and cardiac events by using two-dimensional and color Doppler echocardiography in 229 consecutive patients with mitral valve prolapse. The frequency of moderate and severe mitral regurgitation was significantly higher in patients with a prolapsed posterior leaflet (61%) than in patients with a prolapsed anterior leaflet (25%), and the older the patient, the greater the severity of mitral regurgitation. The occurrence of complications, such as atrial fibrillation, congestive heart failure, and chordal rupture, was significantly greater in prolapsed posterior leaflet cases than in prolapsed anterior leaflet cases, and the occurrence was closely associated with the degree of severity of mitral regurgitation. Multiple logistic regression analysis showed that the severity of mitral regurgitation is a strong prognostic indicator for developing complications. Furthermore in a subgroup of 49 patients tracked for a mean of 4.8 years, the new development of complications was significantly higher in patients who showed a progression in the severity of mitral regurgitation (52%) that in patients without progression in severity (8%). The initial severity of mitral regurgitation was related to the occurrence of cardiac events (mitral valve replacement, infective endocarditis, cerebral embolism and death). The data indicated that the progression of mitral regurgitation is closely associated with the development of complications and cardiac events and suggest that the severity of mitral regurgitation is an important prognostic indicator for the development of complications and cardiac events in patients with mitral valve prolapse.