Effect of Ventricular Pacing on Coronary Blood Flow in Patients with Normal Coronary Arteries

Abstract

Although ventricular pacing is thought to produce impairment of left ventricular function by altering the sequence of ventricular activation and AV dyssynchrony, little is known about the effect of ventricular pacing on coronary blood flow. We measured coronary blood flow and coronary flow reserve in the left anterior descending coronary artery during sinus rhythm, and during both atrial and ventricular pacing at a rate of 100 ppm in 14 patients with normal coronary arteries. The double product increased significantly during both types of pacing. Coronary arterial diameter during ventricular pacing significantly increased compared to that during both sinus rhythm and atrial pacing. Coronary flow velocity during ventricular pacing was significantly lower compared to that during both sinus rhythm and atrial pacing. Coronary blood flow increased significantly during atrial pacing (30.7% +/- 12.1%; P < 0.001), but not significantly during ventricular pacing (23.6% +/- 47.0%; P = ns). While coronary flow reserve during both atrial (3.9 +/- 1.3) and ventricular pacing (3.8 +/- 0.9) was lower compared to its value during sinus rhythm (4.5 +/- 1.5), the difference was not significant. There was a significant positive correlation between the coronary flow reserve during sinus rhythm and the increase of coronary blood flow during ventricular pacing (R2 = 0.78; P < 0.001). We concluded that an increase in coronary blood flow during ventricular pacing is not a common finding regardless of the increase in metabolic demand. The increase of coronary blood flow during ventricular pacing was less in patients with a reduced coronary flow reserve. These findings suggest that preservation of AV synchrony and the presence of a normal sequence of ventricular activation may play an important role in preserving coronary blood flow in this subset of patients.

Noninvasive Pacemaker Stress Echocardiography as a Screening Test for Coronary Artery Disease in Patients With Atypical Angina and Permanent Pacemaker

“…The change in the subendocardial-tosubepicardial flow ratio that's associated with rapid pacing in the presence of a tight coronary stenosis 13) is important for the development of regional dysfunction since the percent regional systolic thickening is linearly and tightly related to the subendocardial flow, and not to the transmural flow. 14) Perfusion scintigraphy may have low specificity or sensitivity in patients with a conventional, permanent PM, and perhaps this because of the impaired coronary flow reserve that's due to alterations of left ventricular mechanical activation and the increased extramural compressive forces. Grines et al 15) suggested that the reduced specificity of thallium scintigraphy in patients with permanent cardiac pacemaker dependency results from a change in the myocardial perfusion following asynchronous contraction of the interventricular septum.…”

Bradyarrhythmias and Physiologic Pacing in the ICU

“…55 In addition, atrial pacing preserves “atrial kick,” helping support cardiac output and increasing coronary perfusion. 56,57 The hemodynamic improvement from restoration of AV synchrony is most notable in patients with pacemaker-syndrome. The syndrome is characterized in patients with single-lead RV pacemakers (including temporary pacers in the ICU) due to a loss of AV synchrony, reduced efficiency of contraction, and ventricular contraction occurring while mitral and tricuspid valves are open.…”

Effects of Pacing Rates on Global and Regional Myocardial Blood Flow

“…Experimental studies of animals with induced LBBB or RVA pacing showed that the resting regional myocardial blood flow (MBF) is lower in early‐activated regions than in late‐activated regions, specifically the septal and lateral areas, respectively 5,6 . These differences in regional perfusion were attributed to regional differences in myocardial work and oxidative metabolism, although global MBF and oxygen consumption remained unchanged 5–7 . A previous study demonstrated that global MBF increases with higher heart rates 8 but to date, the effects of increased heart rate on regional perfusion are not examined at all.…”

“…5,6 These differences in regional perfusion were attributed to regional differences in myocardial work and oxidative metabolism, although global MBF and oxygen consumption remained unchanged. [5][6][7] A previous study demonstrated that global MBF increases with higher heart rates 8 but to date, the effects of increased heart rate on regional perfusion are not examined at all.…”