The objective of the present study was to assess the uniformity of con
traction in reperfused myocardium Regional function was measured by tw
o pairs of piezo-electric crystals oriented in the circumferential and
longitudinal axis of the left ventricular anterior midwall in 10 open
-chest pentobarbitone-anaesthetized cats. The left anterior descending
coronary artery was occluded for 10 min followed by 60 min of reperfu
sion. Myocardial blood flow was measured four times by radioactive lab
elled microspheres: at pre-occlusion, occlusion and after 30 and 60 mi
n of reperfusion. There was a severe and transmural homogenous ischaem
ia during coronary occlusion. The recovery of ejection shortening was
on average 76% at 30 min and 77% at 60 min of reperfusion in circumfer
ential segments versus 25 and 44% in longitudinal segments (P < 0.05).
Diastolic function was deranged in longitudinal segments; at 60 min o
f reperfusion the end diastolic pressure-length relation was still shi
fted rightwards in longitudinal segments, whereas it was normalized in
circumferential segments. In conclusion, systolic and diastolic dysfu
nction in stunned myocardium were more severe in the longitudinal axis
than in the circumferential asis of the feline heart. This indicates
that stunning was more pronounced in longitudinally oriented sub-endoc
ardial fibres which were reflected by the longitudinal segment, despit
e transmural homogenous ischaemia during coronary artery occlusion.