Reflexes unique to myocardial ischemia and infarction.

Although arrhythmias caused by myocardial ischemia are a well recognized cause of sudden death, the potential influence of cardiogenic reflexes originating in areas of ischemia has received less attention. In this study, 12 patients with well documented single vessel coronary artery spasm, with a total of 2,240 episodes of transient transmural ischemia, are described. Continuous electrocardiographic and hemodynamic recordings were analyzed to determine possible relations between the anatomic area of ischemia and patterns of change in blood pressure and heart rate. Of seven patients with ischemia of the posterior or inferior left ventricular wall, six had associated bradycardia and hypotension, an apparent Bezold-Jarisch response. Only one of five patients with anterior ischemia had a similar response. A hypertensive, tachycardiac response resembling the James reflex was seen in two of the patients with anterior ischemia, with an increase in blood pressure of 36/22 +/- 12/6 mm Hg and an increase in heart rate of 8 +/- 3 beats/min. This increase began before the onset of chest pain and was seen even in asymptomatic episodes. These reflexly mediated hemodynamic responses may modulate the direct effects of myocardial ischemia and could play a role in sudden cardiac death.