Comparison of quantitative angiographically derived and measured translesion pressure and flow velocity in coronary artery disease (original) (raw)
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Coronary flow reserve as a physiologic measure of stenosis severity
Journal of the American College of Cardiology, 1990
PART I: Coronary flow reserve indicates functional stenosis severity, but may be altered by physiologic conditions unrelated to stenosis geometry. To assess the effects of changing physiologic conditions on coronary flow reserve, aortic pressure and heart rate-blood pressure (rate-pressure) product were altered by phenylephrine and nitroprusside in 11 dogs. There was a total of 366 measurements, 26 without and 340 with acute stenoses of the left circumflex artery by a calibrated stenoser, providing percent area stenosis with flow reserve measured by flow meter after the administration of intracoronary adenosine. Absolute coronary flow reserve (maximal flow/rest flow) with no stenosis was 5.9 +/- 1.5 (1 SD) at control study, 7.0 +/- 2.2 after phenylephrine and 4.6 +/- 2.0 after nitroprusside, ranging from 2.0 to 12.1 depending on aortic pressure and rate-pressure product. However, relative coronary flow reserve (maximal flow with stenosis/normal maximal flow without stenosis) was independent of aortic pressure and rate-pressure product. Over the range of aortic pressures and rate-pressure products, the size of 1 SD expressed as a percent of mean absolute coronary flow reserve was +/- 43% without stenosis, and for each category of stenosis severity from 0 to 100% narrowing, it averaged +/- 45% compared with +/- 17% for relative coronary flow reserve. For example, for a 65% stenosis, absolute flow reserve was 5.2 +/- 1.7 (+/- 33% variation), whereas relative flow reserve was 0.9 +/- 0.09 (+/- 10% variation), where 1.0 is normal. Therefore, absolute coronary flow reserve by flow meter was highly variable for fixed stenoses depending on aortic pressure and rate-pressure product, whereas relative flow reserve more accurately and specifically described stenosis severity independent of physiologic conditions. Together, absolute and relative coronary flow reserve provide a more complete description of physiologic stenosis severity than either does alone. PART II: Coronary flow reserve directly measured by a flow meter is altered not only by stenosis, but also by physiologic variables. Stenosis flow reserve is derived from length, percent stenosis, absolute diameters and shape by quantitative coronary arteriography using standardized physiologic conditions. To study the relative merits of absolute coronary flow reserve measured by flow meter and stenosis flow reserve determined by quantitative coronary arteriography for assessing stenosis severity, aortic pressure and rate-pressure product were altered by phenylephrine and nitroprusside in 11 dogs, with 366 stenoses of the left circumflex artery by a calibrated stenoser providing percent area stenosis as described in Part I.(ABSTRACT TRUNCATED AT 400 WORDS)
AJP: Heart and Circulatory Physiology, 2006
To evaluate the hemodynamic impact of coronary stenoses, the fractional (FFR) or coronary flow velocity reserve (CFVR) usually are measured. The combined measurement of instantaneous flow velocity and pressure gradient (v-dp relation) is rarely used in humans. We derived from the v-dp relation a new index, dp v50 (pressure gradient at flow velocity of 50 cm/sec) and compared the diagnostic performance of dp v50 , CFVR and FFR. Prior to coronary angiography patients underwent non-invasive stress testing. In all coronary vessels with an intermediate or severe stenosis, the flow velocity, aortic and distal coronary pressure were measured simultaneously with a Doppler and pressure guide wire after induction of hyperemia. After regression analysis of all middiastolic flow velocity and pressure gradient data, the dp v50 was calculated. Using the results of non-invasive stress testing, the dp v50 cut-off value was established at 22.4 mm Hg. In 77 patients, 124 coronary vessels with a mean 39±19% diameter stenosis were analyzed. In 43 stenoses ischemia was detected. We found a sensitivity, specificity and accuracy of 56%, 86% and 76% for CFVR, 77%, 99% and 91% for FFR and 95%, 95% and 95% for dp v50 . To establish that dp v50 is not dependent on maximal hyperemia, dp v50 was recalculated after omission of the highest quartile of flow velocity data, showing a difference of 3%. We found that dp v50 provided the highest sensitivity and accuracy compared to FFR and CFVR in the assessment of coronary stenoses. In contrast to CFVR and FFR assessment of dp v50 is not dependent on maximal hyperemia.
Impairment of coronary flow reserve in aortic stenosis
Journal of Applied Physiology, 2008
Rimoldi OE, Pibarot P. Impairment of coronary flow reserve in aortic stenosis. Coronary flow reserve (CFR) is markedly reduced in patients with severe aortic valve stenosis (AS), but the exact mechanisms underlying this impairment of CFR in AS remain unclear. Reduced CFR is the key mechanism leading to myocardial ischemia symptoms and adverse outcomes in AS patients. The objective of this study was to develop an explicit mathematical model formulated with a limited number of parameters that describes the effect of AS on left coronary inflow patterns and CFR. We combined the mathematical V 3 (ventricularvalvular-vascular) model with a new lumped-parameter model of coronary inflow. One thousand Monte-Carlo computational simulations with AS graded from mild up to very severe were performed within a wide range of physiological conditions. There was a good agreement between the CFR values computed with this new model and those measured in 24 patients with isolated AS (r ϭ 0.77, P Ͻ 10 Ϫ4 ). A global sensitivity analysis showed that the valve effective orifice area (EOA) was the major physiological determinant of CFR (total sensitivity index ϭ 0.87). CFR was markedly reduced when AS became severe, i.e., when EOA was Ͻ1.0 cm 2 , and was generally exhausted when the EOA was Ͻ0.5-0.6 cm 2 . The reduction of CFR that is associated with AS can be explained by the concomitance of 1) reduced myocardial supply as a result of decreased coronary perfusion pressure, and 2) increased myocardial metabolic demand as a result of increased left ventricular workload. modeling; patients AORTIC STENOSIS (AS) CREATES an obstruction to blood flow from the left ventricle (LV) to the aorta, which leads to a LV pressure (Plv) overload. The coronary flow reserve (CFR) is defined as the maximal increase in myocardial blood flow (MBF) above its resting level for a given perfusion pressure when coronary vasculature is maximally dilated. The CFR is generally estimated in practice by calculating the ratio of maximum MBF obtained at maximum coronary artery dilation (i.e., hyperemia) induced by pharmacological agents (adenosine, dipyridamole) to resting MBF. This is an integrated measure of flow through both the large epicardial coronary arteries and the microcirculation (23). An abnormal CFR can be due to narrowing of the epicardial coronary arteries or, in the absence of angiographically demonstrable atherosclerotic disease, may reflect dysfunction of the coronary microcirculation. Patients with AS have an impaired CFR, despite normal coronary arteries , which limits the ability of coronary circulation to increase flow to match myocardial oxygen demand. The reduction of CFR is the key factor responsible for myocardial ischemia in AS patients, and this may contribute to the development of LV dysfunction, symptoms, and adverse outcomes (34). There still persist some uncertainties and controversies as to the mechanisms underlying the impairment of CFR in AS patients (12). The concentric LV hypertrophy typically associated with AS was initially believed to be the main cause of impaired CFR in these patients . Rajappan et al. (34), however, recently reported that CFR correlates better with the hemodynamic indexes of AS severity, i.e., valve effective orifice area (EOA) and transvalvular pressure gradient, than with LV mass. Moreover, in patients with severe AS and no significant obstructive coronary artery disease, ischemic symptoms, such as angina, are generally relieved immediately after aortic valve replacement (AVR), whereas LV hypertrophy gradually regresses over several months. These findings, therefore, suggest that the abnormally high LV workload induced by the stenosis may be one of the key mechanisms responsible for impaired CFR and thus myocardial ischemia in AS.
Circulation, 1995
Background Coronary arteriography is considered the “gold standard” for evaluating the severity of a coronary stenosis. Because the resistance to blood flow through a stenotic lesion depends on a number of lesion characteristics, the physiological significance of coronary lesions of intermediate severity is often difficult to determine from angiography alone. This study of patients with coronary artery disease seeks to determine the relation between myocardial blood flow and flow reserve measured by positron emission tomography (PET) and the percent area stenosis on quantitative coronary arteriography. Methods and Results We studied 28 subjects: 18 patients with coronary artery disease (66±8 years) and 10 age-matched healthy volunteers (64±13 years) with dynamic N-13 ammonia PET imaging at rest and after dipyridamole (0.56 mg/kg). The percent cross-sectional area stenosis was quantified on the coronary arteriograms as described by Brown et al. In the 18 patients, a total of 41 non–i...
The diastolic flow-pressure gradient relation in coronary stenoses in humans
Journal of the American College of Cardiology, 2002
We assessed the feasibility and reproducibility of the instantaneous diastolic coronary flow velocity-pressure gradient relation to characterize different degrees of coronary stenoses. BACKGROUND Assessment of the hemodynamic significance of coronary stenoses can be difficult. Using sensor-tipped guidewires, various physiologic indexes can be determined in the catheterization laboratory. Each of the current methods, however, has limitations.
Pressure-derived measurement of coronary flow reserve
Journal of the American College of Cardiology, 2005
We aimed to validate the technique of measuring the coronary flow reserve (CFR) with coronary pressure measurements against an established thermodilution technique. BACKGROUND The CFR has traditionally required measurement of coronary blood flow velocity with the Doppler wire and, more recently, using a thermodilution technique with the coronary pressure wire. However, recent work has suggested that the CFR may be derived from pressure measurements alone (the ratio of the square root of the pressure drop across an epicardial stenosis during hyperemia to that value at rest). This depends on the assumption that friction losses across a coronary stenosis are negligible.
Journal of Interventional Cardiology, 2002
The human circulation to the human myocardium is unique in multiple ways. There is a great need for oxygenated blood supply to the myocardial muscle. The heart mainly operates on aerobic metabolism. Since the coronary arterial oxygen extraction is at near maximal level (coronary sinus oxygen saturation 25-35%),' myocardial blood flow and oxygenation are critically dependent on coronary vasodilator reserve. Coronary flow reserve (CFR) is defined as the maximal extent of coronary flow relative to the baseline flow elicited by a potent pharmacological stimulus. CFR is a ratio of maximally elicited coronary flow to resting flow. It is 2-5 in humans and 4-7 in experimental animals. Coronary flow stimulators include transient coronary occlusion, angiographic contrast, intracoronary nitroglycerin, adenosine, bradykinin, and papaverine. CFR represents the maximal vasodilator capacity of the total coronary vascular bed largely comprising of the microvascular network and conduit epicardial vessels. CFR is inversely proportional to coronary microvascular resistance if the conduit vessels are normal. Coronary vascular resistance is coronary perfusion pressure divided by basis for assessing critical coronary stenosis. Instantaneous flow response and regional distribution during coronary hyperemia as measures of coronary flow reserve. Am J Cardiol 1974;33:87-94. Pinch C, Schwaiger M. The clinical role of positron emission tomography in management of the cardiac patient. Rev Port Cardiol2ooO. l9(Suppl. 1):189-I 100. Donohue TJ, Kern MJ. Aguirre FV, et al. Assessing the hemodynamic significance of coronary artery stenoses: Analysis of translesional pressure-flow velocity relations in patients. J Am