This article was written in collaboration with Dr. Mustafa Ahmed, Associate Professor of Medicine, Director of the Structural and Interventional Cardiology Program at the University of Alabama, at Birmingham.
CHRONIC AORTIC INSUFFICIENCY:
The most common causes of aortic valve insufficiency (aortic regurgitation) in the US are the bicuspid aortic valve and the primary disease of the aorta or sinuses of Valsalva. In most patients with chronic aortic insufficiency, the course of the disease is slowly progressive with increasing volume load to the LV and resulting adaptation of LV dilatation and hypertrophy.
The familial history is important for determining whether a bicuspid valve or an aortopathy could be responsible for the insufficiency of the aortic valve. Also important in clinical history is to elicit the presence of symptoms or diminution of exercise performance. The presence of symptoms confers a worsened prognosis if aortic valve replacement (AVR) is not performed.
The physical examination can detect the presence of insufficiency at auscultation but despite being specific, it is not a very sensitive method. Other signs of volume overload include a wide pulse pressure (where the systolic blood pressure is much higher compared to the diastolic blood pressure), enlarged and sustained point of maximal impulse (much larger LV by palpation), and an S3 gallop on auscultation.
Transthoracic echo is an invaluable tool to determine the cause of aortic insufficiency, the severity of the insufficiency, and the LV response to the volume overload. Qualitative or semi-qualitative Doppler Echocardiographic measures may be adequate in most instances for evaluating the valve. When the regurgitation jet is >65% of the LV outflow tract, holodiastolic aortic flow reversal is detected in the descending aorta, Vena Contracta >0.6, Regurgitant volume >65% or regurgitant fraction >50%, Effective Regurgitant aortic area (ERO) >0.3 cm2, this usually indicates the presence of a significant valve lesion. But determining the severity of a regurgitant lesion is among the most difficult tasks since it is influenced by hemodynamics. Elevated blood pressure can increase all these parameters. For this reason, it is best to interpret the Doppler findings in the clinical context at the time of the examination.
Measurements of LV systolic function and LV end-systolic dimension or volume are predictive of the development of heart failure symptoms or death and are significant determinants of survival and clinical status after aortic valve replacement. The patients are best evaluated by a heart team approach and in centers with a large experience with aortic valve surgery and low operative mortality. In asymptomatic patients with severe aortic insufficiency and reduced LVEF <55%, surgical intervention is usually recommended. Surgery is also reasonable in those patients with normal EF >55% and severely dilated LV (LVESD >50 mm or indexed diameters of >25 mm/m2), or progressively deteriorating EF from 60% to 55% or enlarging LV diastolic dimensions (>65 mm).
Values for LV size and function vary from different techniques and there is still insufficient data relating to the evaluation of LV volumes and mass by 2D or 3D echo, magnetic resonance imaging (MRI), and outcomes of patients with chronic aortic insufficiency. Other measurements of LV systolic function such as Global longitudinal strain (GLS) have not been studied thoroughly.