Author + information
- Przemyslaw Kwasiborski1,
- Wojciech Czerwiński2,
- Paweł Kowalczyk3,
- Kamil Derbisz2,
- Mateusz Kachel2,
- Adam Janas4,
- Piotr Buszman2,
- Paweł Buszman2 and
- Krzysztof Milewski2
- 1Angiology and hemodynamics laboratory, Regional Specialist Hospital, Międzylesie, Poland
- 2Center for Cardiovascular Research and Development, American Heart of Poland, Katowice, Poland
- 3Department of Biophysics and Human Physiology, Medical University of Warsaw, Warsaw, Poland
- 4Center of Cardiovascular Research and Development, American Heart of Poland, Katowice, Poland
The physiological assessment of a lesion is a key to quality of life and prognosis of a patient with moderate coronary stenosis. Blood flow in coronary arteries occurs primarily during diastole, it is evident especially in the LAD. The systolic phase lasts roughly 300 ms and its duration is almost independent of the heart rate, consequently the higher heart rate the shorter diastole. Flow fluctuations associated with the cardiac cycle directly affect the pressures that are measured during FFR. In this study we tried to estimate that effect theoretically, experimentally in a porcine model and in clinical settings.
The group of 4 healthy domestic pigs we used in experimental arm. Stenoses in RCA and LAD were induced by balloon inflation in previously stented segment of RCA or LAD respectively. Heart rate was stabilized by external cardiac peacemaker. Clinical arm of the study included 9 elective patients with isolated, moderate lesions in LAD or RCA who were admitted for FFR assessment. FFR measurements were repeated 3 times for each heart rate, starting from resting HR and during pacing at 100, 130, 160 (180 for pigs) beats per minute. All FFR measurements were performed after a stable hyperemia was reached.
In experimental arm 33 FFR measurements (14 RCA and LAD 19) were done (Fig. 1.). The experimental results indicate a significant correlation of FFR and HR in LAD (r2 = 0.79, p < 0.0001), which agreed with in silico model (p=0.11). In opposite, the results obtained in RCA indicate a lack of correlation between FFR and HR (r2 = 0.03, p = 0.52). In clinical arm 105 FFR measurements (48 RCA, 57 LAD) were done. Results achieved in LAD indicate that there is a significant correlation between FFR and HR (r=0.53, p=0.00002). Similarly, to the porcine model there is no significant correlation in RCA (r=0.14, p=0.35).
Presented results justify hypothesis of potential influence of HR on FFR value measured in LAD. Theoretical model of FFR-HR dependency developed during the study gives upper estimate of HR impact on FFR that is probable possible to achieve only in the experiment.
IMAGING: FFR and Physiologic Lesion Assessment