Coronary and Systemic Hemodynamic Effects of Cardiac Pacing in Man with Complete Heart Block

Abstract

Twelve subjects with an average age of 65.9 years who had complete heart block had cardiac output and coronary blood flow measured at three different rates of pacing. Cardiac output and calculated external work increased with rate from the slow to the intermediate rate, but declined at the fast rate. Even at the intermediate rate, cardiac output remained low as compared to standards for normal younger subjects. Coronary blood flow and left ventricular oxygen usage increased with cardiac rate. Cardiac efficiency, expressed as left ventricular work divided by left ventricular oxygen consumption, tended to decrease as cardiac rate rose; however, these changes were not statistically significant. Lactate consumption increased with rate, but changes in glucose and pyruvate consumption were not significant. Considering the eirculatory svstem as a whole, the intermediate or normal resting rate was more efficient. At this rate the cardiac output and cardiac work were greatest, and the mixed venous oxygen content (which must reflect body tissue oxygenation) was highest, wlile the cardiac oxygen] consumption and coronary blood flow were intermediate.

Improvement of Cerebral Blood Flow and Cognitive Function following Pacemaker Implantation in Patients with Bradycardia

“…A decrease in renal and coronary blood flow in patients with complete heart block has been reported [4][5][6]. In our study, CCr in creased significantly after pacemaker implan tation.…”

Coronary Circulation During Pacing‐induced Tachycardia

“…In experimental animals in which flow has been studied with very accurate methods coronary flow increased continuously with increasing heart rate (4, 23). In man the same results have been reported in some investigations (8, 24). There are studies, however, showing a decrease in coronary flow on higher heart rates (3, 16).…”

“…Coronary circulation normally responds to increased myocardial oxygen demand with an increase of coronary flow. Different methods have been used in experimental animals and in man to increase oxygen demand of the myocardium, for example exercise (2, 6, 12,14), isoprenaline infusion or other pharmacological agents (2, 26), and pacing-induced tachycardia (PIT) (3, 4, 7, 8,9,16,20,23,24). 1 Present address: Afd.…”

Auswirkungen der elektrischen Reizung des Herzens auf den Koronarkreislauf

“…Der EinfluB von Frequenz~inderungen des Herzens auf die Stromstiirke in den verschiedenen Teilkreisliiufen wurde mehrfach beschricbcn (8,9,17,18,19,20,23). Die untersuchten Frequenzen reichen yon dcr extrcmcn Bradykardie bis zu Werten hocla fiber dem normalen physiologischen Niveau.…”