The flow-function relationship in patients with chronic coronary artery disease and reduced regional function: a
M Baroni1, M A Torres, S Maffei
1CNR Institute of Clinical Physiology, Pisa, Italy. roberta@ifc.pi.cnr.it
Insights
Infra-low dose dipyridamole effectively assesses myocardial viability in coronary artery disease. Patients with resting dysfunction and contractile reserve showed improved function and flow, unlike those with fixed defects.
Area of Science:
- Cardiology
- Diagnostic Imaging
- Physiology
Background:
- Infra-low dose dipyridamole can selectively assess myocardial viability.
- Transesophageal echocardiography Doppler is effective for evaluating coronary flow response.
- Coronary artery disease (CAD) patients with baseline dysfunction require assessment of flow-function relationship during stress.
Purpose of the Study:
- To determine the flow-function relationship during coronary vasodilatory stress in CAD patients with baseline dysfunction.
- To evaluate the utility of dipyridamole stress testing in identifying myocardial viability.
Main Methods:
- Twelve patients with resting dyssynergies and 6 controls underwent assessment.
- Regional function and left anterior descending (LAD) artery blood flow velocity were measured at rest and after dipyridamole (0.28 mg/Kg).
- Patients were categorized as 'Responders' or 'Non-responders' based on functional improvement.
Main Results:
- Controls and 'Responders' showed normal function and flow response to dipyridamole.
- 'Non-responders' exhibited resting dyssynergies but no functional improvement and a blunted flow response.
- Residual flow response during stress was more common in segments with resting dysfunction and contractile reserve.
Conclusions:
- Myocardial segments with resting dysfunction and contractile reserve often show a residual flow response to vasodilator stress.
- Segments with a fixed pattern of dysfunction demonstrate a flat flow response.
- This suggests dipyridamole stress can differentiate viable from non-viable myocardium in CAD.
Background:
Infra-low dose dipyridamole allows one to selectively explore myocardial viability. Transesophageal echocardiography Doppler measurement of left anterior descending coronary artery flow at baseline and following dipyridamole is an efficient tool to assess coronary flow response. Aim of this study was to determine the flow-function relationship during coronary vasodilatory stress in patients with coronary artery disease and baseline dysfunction.
Methods And Results:
Twelve patients with resting dyssynergies and 6 controls underwent assessment of regional function and of left anterior 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 ('Responders') with resting dyssynergies showed an improvement in segments of left anterior descending artery territory, whereas the other six ones ('Non-responders') showed no functional change. Controls and 'Responders' had similar values of resting peak diastolic left anterior descending artery flow velocity both at rest and after dipyridamole, whereas 'Non-responders' showed 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 flow response during coronary vasodilator stress.
