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Regional myocardial blood flow in man during dipyridamole coronary vasodilation
Insights
Dipyridamole infusion significantly increases myocardial blood flow, especially in nonobstructed coronary arteries. This difference in flow helps discriminate between stenotic and non-stenotic coronary arteries.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Assessing regional myocardial blood flow is crucial for diagnosing coronary artery disease.
- Dipyridamole is a vasodilator used in myocardial perfusion imaging.
Purpose of the Study:
- To evaluate the effect of dipyridamole on regional myocardial blood flow.
- To determine if dipyridamole can differentiate between normal and stenotic coronary arteries.
Main Methods:
- Cardiac catheterization was performed on 11 patients.
- Regional myocardial blood flow was measured using the 133Xe washout technique before and after intravenous dipyridamole (0.56 mg/kg).
- Hemodynamic parameters including heart rate and blood pressure were monitored.
Main Results:
- Dipyridamole infusion caused significant increases in heart rate and decreases in systolic blood pressure.
- Regional myocardial blood flow increased markedly in nonobstructed coronary arteries (from 67 to 117 ml/100 mg/min).
- Flow also increased in stenotic arteries (from 57 to 79 ml/100 mg/min), but to a lesser extent, creating a discriminatory difference.
Conclusions:
- Dipyridamole infusion effectively increases myocardial blood flow.
- The differential increase in flow between nonobstructed and stenotic coronary arteries allows for discrimination.
- This technique shows promise for diagnosing coronary artery stenosis.
Abstract:
Regional myocardial blood flow before and after intravenous dipyridamole (0.56 mg/kg) was measured during cardiac catheterization in 11 patients using the 133Xe washout technique. Significant increases in heart rate (75 +/- 4 vs 87 +/- 6, p less than 0.004) and decreases in systolic blood pressure (144 +/- 8 vs 131 +/- 7, p less than 0.02) were observed with dipyridamole infusion. However, double product and cardiac output did not differ before or after drug infusion. Regional myocardial blood flow increased from 67 +/- 3 (SEM) to 117 +/- 3 ml/100 mg/min in myocardial segments supplied by nonobstructed coronary arteries. In stenotic coronary arteries, flow increased from 57 +/- 5 to 79 +/- 9 ml/100 mg/min with dipyridamole. We conclude that dipyridamole infusion results in flow differences which discriminate stenotic from nonstenotic coronary arteries.