European Journal of Cardio-Thoracic Surgery, Vol 5, 598-602, Copyright © 1991 by European Association for Cardio-thoracic Surgery
Global and regional ventricular function following intracoronary application of papaverine
H Schad, W Heimisch, F Haas, R Blasini and N Mendler
Department of Cardiac and Vascular Surgery, German Heart Center, Munich.
Intracoronary injection of papaverine is used to determine coronary flow
reserve in patients. The present study was to investigate the effect of
papaverine on the performance of myocardium with reduced flow reserve. In
nine anaesthetized open-chest dogs a bypass from the aorta to the left
circumflex coronary artery (LCX) was established. Left ventricular
end-diastolic and aortic pressure, dP/dt, stroke volume, LCX blood flow,
and ECG were monitored. The performance of a segment of subendocardial wall
supplied by the LCX was assessed by sonomicrometry. Peak reactive
hyperaemia after 15s bypass occlusion was 1.44 +/- 0.09 times the baseline
flow (41 ml/min), indicating reduced coronary flow reserve. Papaverine was
injected into the bypass (0.3, 0.6, 1.2, 2.5, 5.0 mg/ml, 1 ml in 15s). The
maximum LCX flow following PAPA 0.3 mg was comparable to peak reactive
hyperaemia, but 10-15% higher after injection of 0.6-5.0 mg papaverine.
Systolic shortening of the myocardium (control: 17.5% of end-diastolic
length) became reduced in a dose-dependent fashion (5-25%) for about 1 min
following papaverine injection. Stroke volume (control: 0.94 +/- 0.12
ml/kg) was reduced by about 8%, left ventricular end-diastolic pressure
(control: 6.2 +/- 0.8 mmHg) increased by 15%, and dP/dtmin (control: 1850
+/- 150 mmHg/s) was curtailed by 15-25%. The ECG showed a transient T
inversion and S-T depression following papaverine administration and in one
experiment ventricular fibrillation occurred after the injection of 2.5 mg
papaverine. The observed effects of intracoronary papaverine are consistent
with the theory of transient subendocardial ischaemia arising from a
redistribution of blood flow from the subendocardial to the subepicardial
layers, because of greater vasodilatory capacity in the latter than in the
former.
