Monday, March 26, 2012

Aortic Stenosis | Symptoms, Treatment and Investigations


Obstructed left ventricular outflow due to aortic stenosis leads to increased left ventricular pressure and compensatory left ventricular hypertrophy. To maintain cardiac output large pressure gradient across the valve is required. Cardiac output at rest is maintained within normal limits in most patients with severe aortic stenosis, it often fails to rise normally during exertion. Late in the course of the disease, the cardiac ouput and stroke volume decline (due to LV dysfunction). Decreased flow of blood through the aortic valve causes decreased cardiac output, hypotension and syncope (fainting), myocardial ischemia and angina.


Ischemia in aortic stenosis : Due to hypertrophy, heart requires more blood for oxygenation that may be not be possible in severe aortic stenosis resulting in myocardial ischemia even in the absence of coronary artery disease. High left ventricular pressure may compress the coronary arteries in systole and shorten the diastole phase may lead to reduced coronary blood flow manifesting as myocardial ischemia, angina, arrhythmias and left ventricular failure. This ischemia becomes more severe on exercise.

Etiology
  • Rheumatic heart disease
  • Congenital bicuspid aortic valves
  • Calcification of valves in old age


Clinical Features

Symptoms
  • Long asymptomatic phase
  • Symptomatic aortic stenosis manifests as angina, exercise induced syncope, exertional dyspnea and ultimately heart failure and sudden death. These symptoms appear when the aortic orifice in reduced to one-third of its normal size.
  • On auscultation there is an ejection systolic murmur at aortic area.

Investigations

Xray Chest
  • Chest X-ray may be normal in critical aortic stenosis
  • The heart is usually normal in size or slightly enlarged
  • Post-stenotic dilatation of ascending aorta on PA view is commonly seen.

ECG
  • Left ventricular hypertrophy.
  • Left ventricular strain due to pressure overload. Left atrial enlargement.

Echocardiography
  • This shows thickened, calcified and immobile aortic valve cusp.
  • Detects left ventricular hypertrophy, its systolic and diastolic function.
  • Droppler echocardiography demonstrates the pressure gradient across the valve and the valve area.

Treatment

Medical treatment is not effective for aortic stenosis, any patient who develop any of the three symptoms (angina, syncope or heart failure) is the candidate for valve replacement.
Surgery is not indicated for asymptomatic patients except those with declining left ventricular function, very severe left ventricular hypertrophy and very high gradient (>80 mmHg) or severely reduced valve area (<0.7 cm2).

No comments:

Post a Comment