Valutazione incruenta del flusso coronarico mediante ultrasonografia Doppler dell'arteria mammaria interna anastomizzata coronaria sinistra durante sforzo isometrico

Isometric contraction of small group of muscles is believed to increase heart rate and contractility and arterial pressure without significant changes in systemic arterial resistance. Such a manoeuvre has been employed in this work to study dynamic changes induced in blood flow into coronary bed, in subjects in which an anastomosis of the internal mammary artery to anterior descending coronary artery was performed. Ten patients with no clinical signs of myocardial ischaemia at rest and during exercise, were requested to perform an endurance left handgrip manoeuvre, at 50% of maximal voluntary contraction. Doppler blood velocity curve in the anastomosed mammary artery; non-invasive blood pressure curve at a finger of the right hand by Finapres; the electrocardiogram, were recorded. A significative increase in heart rate and mean and diastolic blood pressure was found. Blood flow significantly increased, approximately in the same percentage as double product was increased. A calculated index of coronary resistance did not show significant changes. In this group of patients, the handgrip manoeuvre may display the ability of the cardiac pump to match its metabolic needs due to increased pressure load, by employing the same developed pressure load as an adequate coronary perfusion pressure. It is suggested to employ this simple test in the routine monitoring of patients with internal mammary artery bypass grafts.