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Diastolic coronary vascular reserve: a new index to detect changes in the coronary microcirculation in hypertrophic
Rob Krams1, Folkert J Ten Cate, Stéphane G Carlier
1Department of Cardiology, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands. krams@erasmusmc.nl
Insights
A modified diastolic coronary conductance (DCVR) effectively detects microcirculation changes in hypertrophic cardiomyopathy. This new measure is more sensitive than coronary flow reserve for studying coronary adaptations in hypertrophy.
Area of Science:
- Cardiovascular Physiology
- Cardiac Imaging and Diagnostics
- Vascular Biology
Background:
- Hypertrophic cardiomyopathy (HCM) is associated with coronary microcirculation disturbances.
- Existing measures lack sensitivity to detect these microcirculatory changes.
- A need exists for a reliable method to assess coronary adaptations in HCM.
Purpose of the Study:
- To introduce a modified diastolic coronary conductance (DCVR) measurement.
- To evaluate the sensitivity of DCVR in detecting coronary microcirculation alterations in human hypertrophy.
- To compare DCVR with traditional coronary flow reserve (CFR) in patients with HCM.
Main Methods:
- Doppler velocity catheters were used in the left anterior descending (LAD) and left circumflex (LCx) coronary arteries of HCM patients and cardiac transplant recipients.
- Diastolic coronary conductance was measured at rest and during maximal hyperemia induced by adenosine.
- Diastolic coronary vasodilator reserve (DCVR) was calculated as the ratio of hyperemic to resting conductance.
Main Results:
- HCM patients exhibited increased left ventricular outflow tract gradients and septal wall thickness.
- Coronary flow reserve was reduced in both LAD and LCx regions of HCM patients.
- DCVR was significantly decreased in the HCM-LAD region, indicating microcirculatory impairment, but not in the HCM-LCx region.
Conclusions:
- Diastolic coronary vasodilator reserve (DCVR) is a sensitive indicator of microcirculatory disturbances in hypertrophic cardiomyopathy.
- DCVR offers an advantage over traditional coronary flow reserve in identifying regional microvascular dysfunction.
- This modified DCVR provides a novel approach for investigating coronary adaptations in hypertrophic conditions.
Objectives:
The present study introduces a modification of the diastolic coronary conductance concept that maintains its sensitive properties to detect changes in the coronary microcirculation in human hypertrophy.
Background:
Decrements of coronary flow in hypertrophy have been explained by changes in the coronary microcirculation. No measure is available to detect these changes.
Methods:
Doppler velocity catheters were introduced into the left anterior descending artery (LAD) and left circumflex coronary artery (LCx) of patients with obstructive hypertrophic cardiomyopathy (HCM) (n = 11) and into the LAD of cardiac transplant recipients (n = 9). The diastolic coronary conductance was measured at rest and after maximal hyperemia induced by a bolus injection of adenosine. Diastolic coronary vasodilator reserve (DCVR) was calculated as the hyperemic diastolic coronary conductance, divided by the coronary conductance during resting conditions.
Results:
Left ventricular outflow tract gradient in the HCM group (83 +/- 31 mm Hg) was significantly higher (p < 0.05). Septal wall thickness was significantly increased (p < 0.05), while wall thickness was unchanged in the posterior wall of the HCM group. The coronary flow reserve was significantly decreased in the HCM-LCx region (to 64 +/- 7% of control) and in the HCM-LAD regions (to 57 +/- 7% of control). The DCVR was only decreased in the HCM-LAD (to 46 +/- 3% of control) and not in the HCM-LCx group (86 +/- 6%, p > 0.05). Esmolol did affect the pressure gradient and systolic shortening, but did not affect the maximal diastolic conductance.
Conclusions:
The DCVR, in contrast with the coronary flow reserve, is decreased in those regions that display a disturbance in the microcirculation and may, therefore, offer a new way to study coronary adaptations in patients with hypertrophy.
