Barnard Health Care

Myxomatous Mv With Trace Mr Image

One benefit of this method is that, in theory, the measurement of MVA is not affected by coexistent mitral regurgitation as flow across the MV orifice and flow across the aliasing point in the LA will not be significantly different in the presence of mitral regurgitation. However, the proximal isovelocity surface area method is technically challenging and it is not commonly used in many laboratories when evaluating mitral stenosis.

conclusion

In summary, the echocardiography assessment of mitral stenosis provides insight into etiology, quantifies hemodynamics, grades severity, reveals "upstream" sequelae, and assists in choosing therapeutic options.

acknowledgment

The author would like to thank the Massachusetts General Hospital echocardiography laboratory for their generous contribution of echocardiography images for this chapter.

suggested reading

Braunwald E, Zipes DP, Libby P. Heart Disease. A Textbook of Cardiovascular Medicine. Philadelphia: WB Saunders, 2001.

Mohan JC, Pater AR, Passey R, et al. Is the mitral valve area flow-dependent in mitral stenosis? A dobuatmine stress echocardiography study. J Am Coll Cardiol 2002;40: 1809-1815.

Oh JK, Seward JB, Tajik AJ. The Echo Manual. Philadelphia: Lippincott Williams and Wilkins, 1999:103-132.

Otto CM. Textbook of Clinical Echocardiography. Philadelphia: WB Saunders, 2000:229-264.

Weyman AE. Principles and Practice of Echocardiography. Philadelphia: Lippincott Wilkind and Williams, 1994.

Wilkins GT, Weyman AE, Abascal VM, Block PC, Palacios IF. Percutaneous balloon dilation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilation. Br Heart J 1988;60: 299-308.

14 Mitral Regurgitation

Jacqueline Suk Danik, MD, mph and Bernard E. Bulwer, MD, mSc

Contents

Introduction

Assessment of MR Etiology and Mechanisms/Case Presentations Case Presentations Assessment of MR Severity

Two-Dimensional Echocardiographic Parameters for Grading MR Severity Doppler Methods for Grading MR Severity Color Flow Doppler Parameters Other Doppler Methods Integrating Indices of Severity Surgical Considerations in MR/Case Presentations Case Presentations TEE and Valve Analysis Suggested Reading introduction

Mitral regurgitation (MR) is one of the most common acquired valvular heart diseases seen in the adult echocardiography practice. Its onset may be acute or chronic, and the etiology can stem from any process that disturbs the architecture of the mitral valve apparatus (Table 1; Figs. 1 and 2).

Echocardiography has several important roles in MR, including:

1. Evaluation of the etiology of MR.

2. Grading the severity of MR.

3. Assessment of its impact on overall cardiac function, especially left ventricular (LV) function.

4. Guidance for further management, including timing of surgical intervention.

Transthoracic echocardiography (TTE) is the modality of choice for evaluation and follow-up of MR and global cardiac function, but transesophageal echocardio-graphy (TEE) plays an important role when differences exist between clinical assessment and TTE findings, or when mitral valve surgery is needed (Table 2).

assessment of mr etiology and mechanisms

The structure of the entire mitral valve apparatus which include the mitral leaflets, chordal attachments, annulus, papillary muscles, and the supporting ventricular walls affect overall function. Defining the etiology of MR is important as it can influence management and prognosis of such patients. Diseases that are primarily structural in origin can be managed differently from individuals with functional MR.

The cases that follow were chosen to highlight several common etiologies of MR. The most common causes of MR in North America include degenerative disease, ischemia, and functional MR.

case presentation 1: trace mitral regurgitation

A 26-yr-old woman was referred for TTE following clinical detection of a faint systolic murmur. She was completely asymptomatic and had no significant medical history (Fig. 2A).

From: Contemporary Cardiology: Essential Echocardiography: A Practical Handbook With DVD Edited by: S. D. Solomon © Humana Press, Totowa, NJ

Table 1 Causes of MR

Mechanism

Diagnosis

Acute MR Structural

Infectious Chronic MR Degenerative/structural

Ischemic and functional

Infectious

Inflammatory

Ruptured chordae tendinae

Ischemic papillary muscle dysfunction and/or rupture Bacterial endocarditis (both normal and prosthetic heart valves)

Myxomatous degeneration of leaflets (mitral valve prolapse) Chordal rupture with flail leaflet

Papillary muscle dysfunction and/or rupture with flail leaflet Paravalvular leak following prosthetic valve replacement Mitral annular calcification

Collagen disorders, for example, Marfan syndrome and Ehlers Danlos syndrome Dilated cardiomyopathy with mitral annular dilatation and apical tethering Bacterial endocarditis (of both normal and prosthetic heart valves) Rheumatic heart disease

Connective tissue disorders, for example, systemic lupus erythematosus, scleroderma

Table 2

Major Indications for Echocardiography in MR

• Diagnosis and evaluation of the etiology/mechanism of MR

• Asessment of hemodynamic severity, including impact on ventricular size, function, and hemodynamics

• Initial assessment and re-evaluation of asymptomatic and symptomatic patients with MR

• Assessment of effects of medical and surgical therapies in MR, including mitral valve repair or replacement

• TEE for pre-operative, intra-operative, and post-operative evaluation of patients with MR

(Figs. 3-7; please see companion DVD for corresponding video for Figs. 3-6).

These images show classic mitral valve prolapse (MVP), one of the most common cardiac valvular abnormalities, which has been reported in 1-3% of North American populations. This particular example demonstrates prolapse of both anterior and posterior leaflets past the mitral annular plane. The leaflets are thickened (>5 mm) and there is concomitant severe regurgitation.

Classic MVP exists when there is exaggerated (>2 mm) superior displacement ("buckling" or "hammocking") of thickened mitral leaflets (>5 mm thick in diastole) beyond the plane of the mitral annulus during late systole. One of the most common reasons for MVP is fibromyxomatous degeneration of the mitral valve, which can lead to leaflet prolapse, chordal rupture, or partial flail of a segment of one or both leaflets. Strict echocardiographic features of MVP are shown in (Table 3). The parasternal long-axis and the apical long-axis views are the best views for the optimal assessment of MVP, and Figs. 4 and 5 (please see companion DVD for corresponding video) are classic examples of MVP. Of note, the normal saddle-shaped profile of the mitral valve leafleats may be exaggerated when viewed from the apical four-chamber window, resulting in overdiagnosis of MVP or "echocardio-graphic heart disease."

The images show trace (trivial) MR. There is a centrally directed jet confined to an area just distal to the mitral leaflet closure line, seen in multiple windows. It is of short duration and low velocity and may simply represent volume displacement when the mitral leaflets close. This can be seen in up to 80% of normal adults increases in prevalence with age and has little pathological significance.

case presentation 2: mitral valve prolapse

The second case is a 33-yr-old woman with a midsystolic click and an end-systolic murmur

Fig. 1. (A) Mitral valve topography: base of heart view. (B) Anterior and posterior mitral valve leaflets and scallops.

Fig. 2. Illustrations showing mitral valve leaflets, scallops (Carpentier nomenclature) and supporting structures. The mitral valve complex includes the mitral annulus, valve leaflets, chordae tendinae (primary, secondary, and tertiary), and their papillary muscle origins, as well as the supporting left ventricle, left atrium, and the aortic root.

Fig. 2. Illustrations showing mitral valve leaflets, scallops (Carpentier nomenclature) and supporting structures. The mitral valve complex includes the mitral annulus, valve leaflets, chordae tendinae (primary, secondary, and tertiary), and their papillary muscle origins, as well as the supporting left ventricle, left atrium, and the aortic root.

Fig. 3. Parasternal long-axis (PLAX) view showing trace mitral regurgitation (arrow). It is also termed "mitral regurgitation closing volume"—indicating mere volume displacement during leaflet closure. (Please see companion DVD for corresponding video.)