Minimally invasive evaluation of coronary microvascular function by electron beam computed tomography

Area of Science:

• Cardiovascular physiology
• Medical imaging
• Microcirculation research

Background:

• Electron-beam computed tomography (EBCT) indicator-dilution methods estimate intramyocardial blood volume (BV) and perfusion (F).
• The relationship BV=aF+b√F characterizes recruitable (a) and nonrecruitable (b) microcirculation components.
• Hypercholesterolemia (HC) may alter microvascular function.

Purpose of the Study:

• Compare EBCT-derived BV and F with Doppler ultrasound-based coronary blood flow (CBF).
• Quantify differential microvascular responses to vasoactive drugs in normal and HC pigs.
• Assess the impact of hypercholesterolemia on myocardial microcirculation.

Main Methods:

• Contrast-enhanced EBCT studies in 14 HC and 14 control pigs.
• Measurement of BV, F, and CBF at baseline and after adenosine and nitroglycerin infusion.
• Analysis of microvascular reserve and functional component distribution.

Main Results:

• Adenosine-induced BV and CBF reserves were attenuated in HC pigs (P<0.03 and P<0.01).
• HC pigs showed consistently lower recruitable BV compared to controls.
• Nonrecruitable BV reserve was also attenuated in HC pigs (P<0.001), indicating impaired resistance vessel function.

Conclusions:

• EBCT enables minimally invasive evaluation of intramyocardial microcirculatory function.
• EBCT can assess microvascular blood volume distribution into functional components.
• This method is valuable for evaluating coronary microcirculation in pathophysiological states like hypercholesterolemia.