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Effect of ventricular pacing on coronary blood flow in patients with normal coronary arteries
M Takeuchi1, Y Nohtomi, A Kuroiwa
1Second Department of Internal Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Insights
Ventricular pacing does not commonly increase coronary blood flow, even with higher metabolic demand. Preserving atrioventricular synchrony and normal ventricular activation is crucial for maintaining coronary blood flow.
Area of Science:
- Cardiology
- Physiology
Background:
- Ventricular pacing may impair left ventricular function by disrupting activation sequences and atrioventricular (AV) synchrony.
- The impact of ventricular pacing on coronary blood flow remains poorly understood.
Purpose of the Study:
- To investigate the effects of ventricular pacing on coronary blood flow and coronary flow reserve in patients with normal coronary arteries.
Main Methods:
- Coronary blood flow and coronary flow reserve were measured in the left anterior descending artery during sinus rhythm, atrial pacing, and ventricular pacing at 100 bpm in 14 patients.
- Double product, coronary arterial diameter, and coronary flow velocity were assessed.
Main Results:
- Ventricular pacing increased coronary arterial diameter but decreased coronary flow velocity.
- Coronary blood flow significantly increased during atrial pacing but not significantly during ventricular pacing.
- Coronary flow reserve was reduced during both pacing types compared to sinus rhythm.
- A positive correlation was found between baseline coronary flow reserve and the increase in coronary blood flow during ventricular pacing.
Conclusions:
- Increased coronary blood flow during ventricular pacing is not consistently observed, irrespective of metabolic demand.
- Patients with reduced coronary flow reserve experienced a lesser increase in coronary blood flow during ventricular pacing.
- Maintaining AV synchrony and normal ventricular activation sequences appears vital for preserving coronary blood flow.
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.