Perfusion versus function: the ischemic cascade in demand ischemia: implications of single-vessel versus multivessel...

Area of Science:

• Cardiovascular Physiology
• Echocardiography
• Ischemic Heart Disease

Background:

• Demand ischemia can lead to abnormalities in myocardial perfusion and function.
• Understanding the sequence and spatial extent of these abnormalities is crucial for diagnosing coronary artery stenosis.
• Differentiating between single-vessel stenosis (SVS) and multivessel stenosis (MVS) may influence the presentation of ischemic changes.

Purpose of the Study:

• To investigate the temporal and spatial relationship between abnormal myocardial perfusion and function during demand ischemia.
• To compare these relationships in the context of single-vessel stenosis (SVS) versus multivessel stenosis (MVS).
• To determine if perfusion abnormalities precede functional abnormalities and their relative spatial extents.

Main Methods:

• Nine dogs underwent either SVS or MVS placement with varying stenosis severity.
• Dobutamine infusion was used to induce demand ischemia.
• Myocardial perfusion (using myocardial contrast echocardiography) and wall thickening (as a measure of function) were assessed at different dobutamine doses.

Main Results:

• Abnormal perfusion was detected at lower dobutamine doses than abnormal wall thickening in SVS.
• The spatial extent of perfusion abnormalities was generally greater than that of functional abnormalities.
• The spatiotemporal discordance between perfusion and function was less pronounced in MVS compared to SVS.

Conclusions:

• The findings support the concept of an ischemic cascade where perfusion deficits occur before functional impairments.
• Abnormal perfusion is a more sensitive indicator of coronary stenosis than abnormal function.
• Dobutamine echocardiography demonstrates higher sensitivity for MVS detection compared to SVS due to distinct patterns of ischemic changes.