Critical medicine topic-CMT 001

MITRAL STENOSIS WITH COEXISTING AORTIC REGURGITATION

 

Introduction

Some patient with rheumatic heart disease presents a diagnostic challenge because, although the clinical findings clearly indicate mitral stenosis (MS), the presence of an additional valvular lesion must also be considered. Careful clinical examination, electrocardiography, echocardiography, and Doppler studies are essential for identifying associated lesions, particularly aortic regurgitation (AR).

---

Evidence for Mitral Stenosis

The diagnosis of mitral stenosis is strongly supported by the classical auscultatory findings:

·        Opening snap (OS)

·        Loud first heart sound (S1)

·        Low-pitched holodiastolic rumbling murmur at the apex

These are characteristic features of rheumatic mitral stenosis.

---

Aortic Regurgitation in Patients with Mitral Stenosis

Many patients with severe mitral stenosis also have an early blowing diastolic murmur heard along the left sternal border. In approximately 90% of these patients, this murmur represents mild aortic regurgitation, which is usually of little hemodynamic significance.

However, approximately 10% of patients with mitral stenosis have severe rheumatic aortic regurgitation. Severe AR can often be recognized by the presence of classical peripheral signs, including:

·        Wide pulse pressure

·        Water-hammer (Corrigan) pulse

·        Evidence of left ventricular enlargement on chest X-ray and ECG

---

Why Severe Aortic Regurgitation May Be Missed

In patients with multivalvular heart disease, a proximal valvular lesion frequently masks the clinical manifestations of a distal lesion.

Consequently, severe mitral stenosis may obscure the diagnosis of significant aortic regurgitation. The expected widened pulse pressure of AR may be absent because severe mitral stenosis limits left ventricular filling and stroke volume.

---

Austin-Flint Murmur versus Mitral Stenosis Murmur

One important diagnostic problem is distinguishing the Austin-Flint murmur of severe aortic regurgitation from the diastolic rumbling murmur of mitral stenosis.

Effect of Amyl Nitrite

Amyl nitrite inhalation:

·        Decreases the Austin-Flint murmur

·        Increases the murmur of mitral stenosis

Effec t of Handgrip and Squatting

Isometric handgrip and squatting:

·        Increase the diastolic murmur of aortic regurgitation

·        Increase the Austin-Flint murmur

·        Produce little or no change in the murmur of mitral stenosis

In this patient, the responses to amyl nitrite and handgrip are consistent with the presence of an Austin-Flint murmur, indicating significant aortic regurgitation.

---

Electrocardiographic Clues

The ECG demonstrates:

·        Left atrial enlargement

·        Left ventricular hypertrophy

·        Left-axis deviation

These findings are not consistent with isolated mitral stenosis.

Left ventricular hypertrophy strongly suggests the presence of aortic regurgitation or aortic stenosis. Since the patient has a murmur typical of AR, aortic regurgitation is the more likely diagnosis.

There is no evidence of:

·        Tricuspid stenosis

·        Mitral regurgitation

---

Further Diagnostic Evaluation

Further confirmation should include:

Echocardiography

Important findings include:

·        Diastolic fluttering of the anterior mitral leaflet

·        Assessment of mitral valve morphology

·        Evaluation of left ventricular size and function

Doppler Echocardiography

Two-dimensional Doppler echocardiography is highly sensitive, detecting more than 90% of cases of aortic regurgitation. It accurately demonstrates the regurgitant jet and estimates the severity of AR.

Cardiac Catheterization

Cardiac catheterization may be performed when non-invasive investigations are inconclusive or before valve surgery to assess:

·        Hemodynamics

·        Severity of valvular lesions

·        Coronary artery anatomy

---

Management

Patients with severe rheumatic mitral stenosis and significant aortic regurgitation are best treated with combined mitral and aortic valve replacement.

Although double-valve replacement effectively corrects both lesions, it carries:

·        Higher operative risk

·        Lower long-term survival compared with single-valve replacement

---

Prognosis

According to Kirklin:

·        Five-year survival after double-valve replacement: approximately 70%

·        Five-year survival after single-valve replacement: approximately 80%

Patients with markedly dilated ventricles, particularly those with combined aortic regurgitation and mitral regurgitation, generally have a poorer prognosis than those with other combinations of valvular disease.

---

Key Clinical Pearls

·        Rheumatic mitral stenosis may mask significant aortic regurgitation.

·        A widened pulse pressure may be absent despite severe AR when severe MS is present.

·        Austin-Flint murmur can mimic the diastolic murmur of mitral stenosis.

·        Amyl nitrite decreases the Austin-Flint murmur but accentuates the murmur of mitral stenosis.

·        Handgrip and squatting increase the murmurs of AR and Austin-Flint murmur but have little effect on the murmur of MS.

·        ECG evidence of left ventricular hypertrophy suggests an associated aortic valve lesion rather than isolated mitral stenosis.

·        Doppler echocardiography is the investigation of choice for confirming associated aortic regurgitation.

·        Combined aortic and mitral valve replacement is the definitive treatment for severe double-valve disease.

 

DR.C.GANESAN M.D.,

PROFESSOR OF MEDICINE