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Phasic aortocoronary bypass graft blood velocity during ventricular arrhythmias in man
Insights
Ventricular arrhythmias significantly reduce aortocoronary bypass graft blood flow, particularly during tachycardia. Aggressive treatment of these arrhythmias is recommended for patients with bypass grafts to maintain graft function.
Area of Science:
- Cardiovascular Physiology
- Vascular Surgery
Background:
- Aortocoronary bypass grafts are crucial for myocardial perfusion.
- Ventricular arrhythmias can compromise cardiac output and coronary blood flow.
Purpose of the Study:
- To quantify the impact of ventricular arrhythmias on aortocoronary bypass graft blood velocity.
- To assess the relationship between arrhythmia characteristics and graft flow dynamics.
Main Methods:
- Doppler ultrasonic flowmeter catheter used to measure phasic blood velocity in aortocoronary bypass grafts.
- Measurements were taken in 16 conscious subjects during induced ventricular extrasystoles and tachycardia.
Main Results:
- Ventricular extrasystoles reduced peak systolic and diastolic graft velocities by 20-80%.
- Ventricular tachycardia decreased peak graft blood velocity by an average of 50%.
- Arrhythmia-induced flow changes were more pronounced during systole, with a post-arrhythmia "overshoot" observed.
Conclusions:
- Ventricular arrhythmias adversely affect aortocoronary bypass graft function.
- Findings support aggressive management of ventricular arrhythmias in patients with bypass grafts to preserve graft patency and function.
Abstract:
With use of the Doppler ultrasonic flowmeter catheter, phasic aortocoronary bypass graft blood velocity was measured in 16 conscious subjects during ventricular arrhythmias. Ventricular extrasystoles reduced peak systolic and diastolic graft blood velocities by 20 to 80 percent, generally in relation to their respective coupling intervals. When extrasystoles appeared in closely coupled salvos diastolic bypass blood velocity virtually ceased. Nineteen episodes of ventricular tachycardia produced an average 50 percent decrease in peak graft blood velocity (control mean +/- 1 standard deviation blood velocity 28 +/- 11 cm/sec; value during ventricular tachycardia 14 +/- 8 cm/sec, P less than 0.001). An "overshoot" of peak blood velocity was observed after ventricular extrasystoles and tachycardia. All such changes in aortocoronary bypass blood velocity related to tachyarrhythmia were more prominent during the systolic fraction of flow. It is concluded that (1) ventricular arrhythmias adversely influence aortocoronary bypass graft function, and (2) this finding supports an aggressive approach to the treatment of these arrhythmias in subjects with bypass grafts.
