Assessment of microcirculatory remodeling with intracoronary flow velocity and pressure measurements: validation with...

Area of Science:

• Cardiology
• Transplant Medicine
• Microcirculation Research

Background:

• Intracoronary physiology is validated for epicardial stenoses, but its utility for coronary microcirculation is less established.
• This study compares intracoronary physiological indices with structural microcirculatory changes in transplanted hearts.

Purpose of the Study:

• To evaluate the effectiveness of intracoronary physiological indices in assessing structural changes in the coronary microcirculation of cardiac allografts.
• To determine the correlation between intracoronary measurements and histological findings of microvascular remodeling.

Main Methods:

• Four intracoronary physiological indices were measured in 17 cardiac allograft patients during maximal hyperemia.
• Quantitative morphometry of endomyocardial biopsies assessed arteriolar obliteration, arteriolar density, and capillary density.
• Regression analysis was used to correlate physiological indices with histological findings.

Main Results:

• The instantaneous hyperemic diastolic velocity-pressure slope showed significant correlation with arteriolar obliteration (r=0.58) and capillary density (r=0.60).
• Arteriolar obliteration and capillary density independently predicted instantaneous hyperemic diastolic velocity-pressure slope values (r=0.84).
• Coronary resistance index correlated with capillary density (r=0.70), while coronary flow velocity reserve and coronary resistance reserve did not significantly correlate with structural changes.

Conclusions:

• Intracoronary indices, particularly instantaneous hyperemic diastolic velocity-pressure slope, are superior to coronary flow velocity reserve for detecting structural microcirculatory changes.
• Arteriolar obliteration and capillary rarefaction are independent determinants of microcirculatory hemodynamics in cardiac allografts.