Effects of modified pharmacologic stress approaches on hyperemic myocardial blood flow.
Pharmacologic stress testing with 0.56 mg/kg of intravenous dipyridamole is frequently used to noninvasively detect coronary artery disease (CAD). However, high-dose dipyridamole (0.80 mg/kg) or the combination of standard-dose dipyridamole (0.56 mg/kg) with the isometric handgrip maneuver might evoke a greater coronary hyperemic response.


METHODS
To evaluate the effect of modified pharmacologic stress tests, myocardial blood flow as quantified in 11 male subjects (mean age: 27 +/- 7 yr) during standard-dose dipyridamole (0.56 mg/kg), high-dose dipyridamole (0.80 mg/kg) and standard-dose dipyridamole combined with the isometric handgrip exercise using dynamic PET and a two-compartment model for 13N-ammonia.


RESULTS
Systolic blood pressure, heart rate and rate pressure product remained unchanged from standard to high-dose dipyridamole but increased with the addition of the isometric handgrip. Myocardial blood flow was unchanged from standard to high-dose dipyridamole but was lower with the addition of the isometric handgrip.


CONCLUSIONS
The hyperemic response induced by standard-dose dipyridamole cannot be further enhanced by high-dose dipyridamole. The addition of the isometric handgrip exercise results in a modest, but significant decline in hyperemic blood flow possibly due to increased extravascular resistive forces or an increase in a mediated coronary vasoconstriction associated with exercise.
Czernin
J
J
Department of Molecular and Medical Pharmacology, UCLA School of Medicine 90095-6948, USA.
Auerbach
M
M
Sun
K T
KT
Phelps
M
M
Schelbert
H R
HR
D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000503:physiopathology; D004176:Dipyridamole / Q000008:administration & dosage; D015444:Exercise / Q000502:physiology*; D018737:Hand Strength; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000209:etiology; D007091:Image Processing, Computer-Assisted; D008297:Male; D014055:Tomography, Emission-Computed / Q000379:methods*; D014655:Vascular Resistance / Q000502:physiology
D004176:Dipyridamole