The flow-function relationship in patients with chronic coronary artery disease and reduced regional function: a Doppler transesophageal and bidimensional transthoracic echocardiography study

Background: Infra-low dose dipyridamole allows one to selectively explore m yocardial viability. Transesophageal echocardiography Doppler measurement o f left anterior descending coronary artery flow at baseline and following d ipyridamole is an efficient tool to assess coronary flow response. Aim of t his study was to determine the flow-function relationship during coronary v asodilatory stress in patients with coronary artery disease and baseline dy sfunction. Methods and results: Twelve patients with resting dyssynergies a nd 6 controls underwent assessment of regional function and of left anterio r descending blood flow velocity. Flow and function were evaluated at rest and following infra-low dose dipyridamole (0.28 mg/Kg over 4 min). Controls showed a normal function at rest and after dipyridamole. Six patients ('Re sponders') with resting dyssynergies showed an improvement in segments of l eft anterior descending artery territory, whereas the other six ones ('Non- responders') showed no functional change. Controls and 'Responders' had sim ilar values of resting peak diastolic left anterior descending artery flow velocity both at rest and after dipyridamole, whereas 'Non-responders' show ed a blunted flow response to dipyridamole. Conclusion: Myocardial segments with a resting dysfunction and a contractile reserve more often exhibit a residual flow response, whereas segments with fixed pattern show a flat flo w response during coronary vasodilator stress.