Related Experiment Videos
Coronary dilation with standard dose dipyridamole and dipyridamole combined with handgrip
J D Rossen1, I Simonetti, M L Marcus
1Department of Internal Medicine and Cardiovascular Division, University of Iowa, Iowa City 52242.
Insights
Standard intravenous dipyridamole doses may not achieve maximal coronary vasodilation. Isometric handgrip did not enhance coronary flow reserve during dipyridamole infusion in patients with normal coronary arteries.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Intravenous dipyridamole is a common pharmacologic stress agent for cardiac imaging.
- Standard dipyridamole doses may not consistently achieve maximal coronary vasodilation.
Purpose of the Study:
- To compare coronary vasodilation from standard dipyridamole with maximal vasodilation from intracoronary papaverine.
- To evaluate the effect of isometric handgrip on coronary blood flow velocity during dipyridamole infusion.
Main Methods:
- Coronary vasodilation was assessed in 12 patients with normal coronary arteries.
- Coronary blood flow velocity was measured using a 3F Doppler catheter.
- Isometric handgrip was added during dipyridamole infusion to assess its impact.
Main Results:
- Coronary flow reserve was significantly lower after dipyridamole (3.7 ± 1.2) compared to papaverine (4.4 ± 0.5).
- Coronary vascular resistance index was higher with dipyridamole than with papaverine.
- Isometric handgrip increased heart rate and blood pressure but did not alter coronary flow reserve or coronary caliber.
Conclusions:
- Standard dipyridamole dosing may be insufficient for maximal coronary vasodilation.
- Isometric handgrip does not augment coronary vasodilation induced by dipyridamole in patients with normal coronary arteries.
Abstract:
Intravenous dipyridamole is widely used to produce coronary vasodilation during cardiac imaging procedures. However, the routinely used dose of dipyridamole (0.56 mg/kg IV over 4 min) does not always result in maximal coronary dilation. The addition of isometric handgrip during dipyridamole coronary dilation has been reported to substantially increase coronary blood flow over dipyridamole alone. We compared the coronary vasodilation resulting from infusion of the standard dose of dipyridamole with that resulting from a maximally dilating dose of intracoronary papaverine in 12 patients with angiographically normal coronary arteries. We also assessed the effect on coronary blood flow velocity of the addition of isometric handgrip during dipyridamole coronary dilation. Changes in coronary blood flow velocity were measured with a 3F coronary Doppler catheter. The coronary flow reserve (peak/resting coronary flow velocity ratio) after dipyridamole (3.7 +/- 1.2 [mean +/- SD] was less than that seen after papaverine (4.4 +/- 0.5, p less than 0.05), and the coronary vascular resistance index during dipyridamole coronary vasodilation (0.28 +/- 0.09) was greater than during papaverine (0.22 +/- 0.03, p less than 0.05). The dipyridamole coronary flow reserve was less than 3.0 in four subjects and was 2.0 or less in two subjects. The addition of isometric handgrip to dipyridamole coronary vasodilation produced an 8% increase in mean heart rate and a 17% increase in mean arterial pressure, but coronary flow reserve was unchanged (3.8 +/- 1.1 before handgrip vs. 4.0 +/- 1.1 with handgrip). Quantitative angiography in six patients revealed no change in coronary caliber with the addition of handgrip.(ABSTRACT TRUNCATED AT 250 WORDS)