Transluminal, subselective measurement of coronary artery blood flow velocity and vasodilator reserve in man
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A new Doppler catheter accurately measures coronary blood flow velocity (CBFV) in the catheterization lab. This tool enables precise assessment of coronary vasodilator reserve, improving studies of heart circulation.
Area of Science:
- Cardiovascular Research
- Medical Devices
- Diagnostic Technology
Background:
- Assessing coronary blood flow and vasodilator reserve in catheterization labs is challenging due to methodological limitations.
- Accurate measurement of coronary blood flow velocity (CBFV) is crucial for understanding coronary artery function.
Purpose of the Study:
- To develop and validate a novel Doppler catheter for subselective measurement of phasic CBFV.
- To assess the safety and efficacy of this new catheter in animal models and human patients.
- To evaluate the measurement of coronary vasodilator reserve using this technique.
Main Methods:
- Development and validation of a small Doppler catheter for intraluminal CBFV measurement.
- Comparative studies in anesthetized calves using epicardial probes and coronary sinus flow measurements.
- Safety assessments including endothelial permeability and histological examination.
- Clinical application in human patients to measure CBFV and vasodilator responses to pharmacologic agents.
Main Results:
- Intraluminal CBFV measurements correlated highly with epicardial probe data (r=0.95) and coronary sinus flow (r=0.97).
- The catheter demonstrated minimal coronary obstruction and acceptable safety profiles, with minor endothelial permeability changes and no significant thrombus formation.
- Stable CBFV recordings were achieved in 70% of patients, with one case of vasospasm.
- Pharmacologic vasodilation (dipyridamole, meglumine diatrizoate) significantly increased CBFV, with dipyridamole showing greater effect.
Conclusions:
- The validated Doppler catheter provides accurate and reliable phasic CBFV measurements in the catheterization laboratory.
- This method allows for effective assessment of coronary vasodilator reserve, overcoming previous limitations.
- The technique holds promise for advancing research and clinical evaluation of the coronary circulation in humans.
Abstract:
Assessment of coronary blood flow and the vasodilator reserve capacity of individual coronary arteries in the catheterization laboratory has been hampered by methodologic limitations. We have developed and validated a small Doppler catheter that can subselectively measure phasic coronary blood flow velocity (CBFV). In seven anesthetized calves, CBFV was varied from 0.1 to 5.7 times control CBFV. Changes in mean CBFV measured intraluminally by catheter in the left anterior descending and left circumflex arteries were similar to those measured simultaneously with an epicardial Doppler probe on the surface of the same vessel (n = 85, r = .95, slope = 1.04) and to changes in coronary sinus flow (n = 69, r = .97, slope = 1.06) measured with timed venous collections. Identical maximal coronary reactive hyperemic responses with the catheter present and absent in the artery being studied demonstrated that coronary obstruction by the catheter was minimal. Safety studies in six additional calves demonstrated that the catheter caused small changes in coronary endothelial permeability. Histologic studies revealed no endothelial denudation or thrombus formation. Stable phasic recordings of coronary blood flow velocity have been obtained in 58 of 70 patients studied. One of the 70 patients studied had abrupt coronary occlusion probably related to catheter-induced vasospasm. In 10 normal patients, intracoronary meglumine diatrizoate increased CBFV to 3.5 times that at rest (range 2.8 to 5.0). CBFV rose 5.0-fold after an intravenous infusion of dipyridamole (range 3.8 to 7.0). In each patient, dipyridamole produced greater vasodilation than meglumine diatrizoate. The time- and dose-response characteristics to dipyridamole infusion were heterogeneous, underscoring the advantage of continuous on-line measurement of CBFV in the measurement of vasodilator reserve. This method of measuring CBFV and assessing vasodilator reserve in the catheterization laboratory should facilitate studies of the coronary circulation in man.