A bioenergetics assessment of aortic regurgitation: A new tool to assess severity?

Aortic regurgitation is frequently classified as mild, moderate or severe based on echocardiography. Patients with mild aortic regurgitation are usually managed medically. Decisions with regard to moderate aortic regurgitation can be difficult. We hypothesise that mild aortic regurgitation as assessed volumetrically can in fact be moderate to severe when analysed from a bioenergetics point of view. The conservation of energy predicts that any regurgitant volume will require the heart to provide more work energy to support the circulation. Aortic regurgitation involves the left ventricle imparting potential energy, via blood pressure, and kinetic energy, via increased ejected volume and velocity respectively. This implies that regurgitant volume, ejection velocity, diastolic and systolic blood pressure, heart rate, and regurgitant orifice area are all important factors. We present limited data to demonstrate our hypothesis. A bioenergetic analysis of aortic regurgitation, reveals that correlation between regurgitant volume and effective regurgitant orifice can be poor in certain physiological circumstances. In addition we identify the importance of systolic and diastolic blood pressure, and heart rate control in patients with aortic regurgitation. The concept that mild aortic regurgitation can be ignored is from an engineering point fundamentally flawed in some cases.