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Due to valve problems in AR, whether with the leaflet or aortic dilatation, get regurgitation of blood from aorta
back into the LV during diastole.
With each contraction, the LV must pump out both extra, regurgitant volume and normal volume from the LA.
Hemodynamic compensation due to Frank-Starling mechanism:
increases stroke volume and maintains normal end-systolic volume
Severity of AR depends on:
size of regurgitant aortic orifice
pressure gradient across aortic valve during diastole
duration of diastole
Acute vs. Chronic AR:
LV is normal size and relatively non-compliant
Volume load of regurg causes LV diastolic pressure to rise
Suddenly high diastolic pressure transmitted to LA and pulmonary circulation (can produce dyspnea and pulmonary edema)
Usually a surgical emergency requiring Aortic Valve Replacement.
LV undergoes compensation due to long-standing regurgitation.
Get mostly LV volume overload, but also some pressure overload – so get both dilatation and some hypertrophy
Less pressure transmitted to the LA and the pulmonary circulation
Allowing aorta to regurgitate a large volume during diastole causes aortic (and systemic) diastolic pressure to drop substantially).
Combo of high LV stroke volume (inc systolic pressure) and reduced aortic diastolic pressure gives a widened pulse pressure.
Decreased aortic diastolic pressure Æ dec coronary perfusion pressure, reducing myocardial oxygen supply to the large LV…can produce angina (even without atherosclerotic coronaries)
(Chronic) left ventricular hypertrophy results in systolic dysfunction Æ less forward CO and increase in LA and pulmonary pressures Æ patient gets symptoms of CHF
Chronic AR shows an enlarged LV silhouette.
Acute AR more likely to show pulmonary vascular congestion.
Echocardiography: Doppler echocardiography can identify and quantify degree of AR and can often identify the cause of the AR.
Cardiac Catheterization: used with contrast angiography for evaluation of LV function, quantification of the degree of AR, assessment of coexisting coronary artery diseases
Treatment: (surgical intervention not recommended till have regularly occurring symptoms and/or LV dysfunction)
60% of patients with asymptomatic chronic AR and normal LV contractile function will still be asymptomatic at their 10-year follow-up.
Just need regular clinical evaluation, periodic assessment of LV function (by echo), and antibiotic prophylaxis for endocarditis.
Symptomatic AR with preserved LV function:
May respond to diuretics and afterload reducing vasodilators (like ACE inhibitors).
Ca2+ channel blocker (nifedipine) shown to reduce LV enlargement, increase LV ejection fraction, delay need for valve surgery in patients.
Symptomatic patients w/ severe chronic AR or asymptomatic patients w/ impaired LV contractile function:
Need surgical valve replacement (SVR) to prevent further deterioration of LV function.