Doppler ultrasound in assessing systolic left ventricular function in cardiovascular patients.

Determination of left ventricular (LV) function is of vital importance in cardiovascular medicine and surgery. Various methods have been introduced to achieve this goal but a noninvasive method is more appropriate as it could be used during exercise to follow-up patients and study the response to medical or surgical intervention. The Doppler ultrasound technique of transcutaneous aortovelography (TAV) has been introduced as a successful approach using a 2 MHz transducer to measure the aortic blood velocity in the aortic arch. From the Doppler ultrasound signals the systolic velocity integral is derived (Sd; the stroke distance which is an index of stroke volume) and its percentage change at maximal-tolerated supine exercise (% delta Sd). The latter was found to be a function of LV ejection fraction and thus proved to be a useful approach to assess LV function in patients with coronary artery disease. Using TAV it was found that coronary artery bypass grafting improves LV function during exercise (rather than at rest) irrespective of the presence of a history of myocardial infarction prior to the operation. In patients with intermittent claudication assessment of LV function proved of great use. The % delta Sd was significantly lower in claudicants with positive stress ECG tests than those with negative test. There was a linear correlation (r = 0.51) between the % delta Sd and the percentage change in the ankle/brachial systolic blood pressure index in response to standard 1 minute of exercise. Assessment of LV function in cardiovascular patients is thus of great clinical importance and provides more insight into the mechanism of the disease and assess the response to management.