Peak Diastolic Coronary Flow Velocity Research Articles

Clinical and functional determinants of coronary flow reserve in non-ischemic dilated cardiomyopathy: An echocardiographic study

Coronary flow reserve (CFR) is impaired in non-ischemic dilated cardiomyopathy (DCM). Mechanisms by which such impairment occurs are still unknown, but cofactors such as diastolic compressive force, left ventricular hypertrophy, and microvascular disease have been implied. In order to characterize the determinants of CFR in non-ischemic DCM, we evaluated 110 non-ischemic DCM patients (58 men; age=61±12 years) and 21 age- and gender-matched control patients (14 men; age=59±13 years) by transthoracic ( n=88) or transesophageal ( n=22) dipyridamole (0.84 mg/ kg in 10′) stress echocardiography. All patients showed angiographically normal coronary arteries. Non-ischemic DCM patients had an ejection fraction <45% while control patients had normal left ventricular systolic function. CFR was assessed on LAD by pulsed Doppler as the ratio of maximal vasodilation (dipyridamole) to rest peak diastolic coronary flow velocity. Mean CFR value was 2.0±0.6 for DCM patients and 3.2±0.5 for controls ( p<0.01). At individual non-ischemic DCM patient analysis, 46 patients had normal CFR≥2 (Group 1) and 64 patients had abnormal CFR<2 (Group 2). On univariate analysis, CFR reduction correlated with NYHA functional class ( r=−0.33, p=0.001), left ventricular ejection fraction ( r=0.23, p=0.02), end-systolic volume ( r=−0.23, p=0.02), systolic pulmonary artery pressure ( r=−0.42, p=0.0001), deceleration time ( r=0.24, p=0.02). Logistic multiregression analysis showed that only NYHA functional class significantly and negatively correlated with CFR (odds ratio=0.9; 95% confidence intervals: 0.03–.35, p=0.0001). In patients with non-ischemic DCM, CFR is reduced but with substantial individual variability, only partially accounted for by level of systolic and diastolic dysfunction. The clinical functional class is the strongest predictor of CFR reduction in these patients, with lowest flow reserve found in more advanced NYHA class.

Feasibility of Measuring Coronary Flow Velocity and Reserve in the Left Anterior Descending Coronary Artery by Transthoracic Doppler Echocardiography in a Relatively Obese American Population

Transthoracic Doppler echocardiography (TTDE) assessment of coronary flow velocity reserve (CFVR) has been validated in Asian and European centers. This methodology has not gained acceptability in the United States due to the bias that coronary flow velocity (CFV) by TTDE might be difficult in an obese population with relatively poor acoustic windows. Baseline CFV in the left anterior descending coronary artery (LAD) by TTDE was obtained in 67 nonselected American patients. A subset of 38/67 received adenosine infusion for measuring CFVR of the LAD. The aim of this study was twofold: (1) to determine the feasibility of measuring CFV and CFVR in the LAD by TTDE in a relatively obese American population, and (2) to compare CFV and CFVR values in this population with those previously obtained in a group of Japanese patients. The mean body mass index (BMI) of the American population (28 +/- 6 kg/m2, range: 18-46 kg/m2) was significantly higher than that of the Japanese group (23 +/- 4 kg/m2, range: 15-37 kg/m2). Twenty-five American patients were classified as obese (BMI >30 kg/m2). Baseline CFV was obtained in 60/67 patients (feasibility: 90%) with a 10% need for intravenous contrast agent to enhance the delineation of the CFV envelope. The success rate in recording CFVR in American patients (92%) was nearly identical to that of a Japanese group (99%). The time-averaged peak diastolic coronary flow velocity increased from 15.6 +/- 5.5 cm/sec at baseline to 47.1 +/- 17.9 cm/sec during adenosine infusion, and CFVR was calculated to be 3.22 +/- 1.15 (range: 0.94-5.69). Intraobserver and interobserver variability for the CFV recording was 4.7 and 6.2%, respectively. These results suggest that the noninvasive measurement of CFV and CFVR of the LAD is feasible even in a relatively obese American population. Furthermore, the success rates for recording CFV and CFVR are similar to those measured in a Japanese population. This methodology has the potential to provide useful physiological information on the coronary circulation in American patients.

Non-invasive assessment of coronary flow reserve in idiopathic dilated cardiomyopathy: hemodynamic correlations

Impaired vasodilator myocardial blood flow response has been observed in dilated cardiomyopathy (DCMP). However, the mechanisms responsible for this blunted response are not clear. In the present study, we investigated whether the blunted vasodilator flow response is related to indices of left ventricular performance in patients with idiopathic dilated cardiomyopathy. Eighteen DCMP patients and 12 healthy subjects (C) underwent transoesophageal echocardiography within 48 h from cardiac catheterization. Coronary flow velocity reserve (CFR) was measured in the proximal LAD as the ratio of the peak diastolic coronary flow velocity (Vd-M) after intravenous administration of adenosine to peak baseline diastolic flow velocity (Vd-R). Left ventricular (LV) mass index was positively correlated with baseline coronary diastolic velocity (r=0.415; p=0.043) and inversely correlated with coronary flow reserve (r=-0.570; p=0.003). The baseline coronary diastolic velocity was higher in DCMP vs C (56+/-13 cm/s vs 35+/-12 cm/s; p=0.04). In DCMP pts Vd-R positively correlated with end-diastolic wall stress (r=0.654; p=0.01). Vd increased in both C (96+/-32 cm/s; p<0.05 vs baseline) and DCMP patients (108+/-20 cm/s; p<0.01 vs baseline). The CFR was lower in DCMP patients vs C (1.93+/-0.78 vs 2.99+/-1.01; p=0.009). In DCMP pts CFR was negatively correlated with right atrial pressure (r=-0.595; p=0.015), LVEDP (r=-0.576; p=0.015), pulmonary capillary wedge pressure (PCWP: r=-0.772; p<0.001) and positively with ejection fraction (EF: r=0.683; p=0.003). Pts with DCMP have lower CFR compared to controls. This blunted CFR is due to higher baseline coronary flow and reflects higher wall stress. The close relation between CFR and EF, PCWP and LVEDP suggests that not only a higher baseline Vd but also compressive forces due to left ventricular dysfunction might be responsible for the observed blunted adenosine-mediated coronary vasodilation.

Coronary Artery Flow Velocity Pattern Predicting Myocardial Recovery after Acute Anterior Myocardial Infarction

Background and Objectives:The relationship between the coronary artery flow velocity pattern on the distal left anterior descending coronary artery (LAD), using transthoracic Doppler echocardiography (TTE) and myocardial recovery, following an acute myocardial infarction (MI), has not been studied. Subjects and Methods:The coronary flow velocity at the distal LAD was recorded with TTE, immediately, on the 7th day, and at an average, on the 10th month, in 36 patients following an acute anterior MI. The peak diastolic coronary flow velocity (PDV), the initial velocity pattern and alteration in the velocity pattern, during the follow-up period, were analyzed by the changes in the left ventricular systolic function and the anterior apical wall motion. The subjects were divided into two groups: the recovery (R) group: n=24, M:F=14:10, mean age=60±9 yrs; and the non-recovery (NR) group: n=12, M:F=11:1, mean age=61±11 yrs, according to their myocardial recovery status. Results: The early flow velocity at the distal LAD, using TTE after MI, was divided into 4 patterns; a normal biphasic flow pattern, with a larger diastolic and a smaller systolic component; a pattern, with slow flow and deceleration slope; a pattern, with a retrograde flow; and a pattern, with a rapid diastolic deceleration slope and an early systolic reversal flow. A normal biphasic flow pattern was observed in 16 (66%) of the R-group (n=24), and 1 (8%) of the NR-group (n=12) (p=0.001) patients. A rapid diastolic deceleration slope and an early systolic reversal flow pattern was only observed in 4 of the NR-group (n=12) (p=0.003) patients. Conclusion:The patterns, with a rapid diastolic deceleration slope and a systolic retrograde flow, early after MI, and a persistent slow flow velocity during follow up, are related to poor myocardial recovery following an acute anterior MI. (Korean Circulation J 2003;33 (4):259-268)

Analysis of Coronary Artery Flow Patterns in Patients with Chest Pain and Normal Coronary Angiogram: Study Using Transthoracic Doppler Echocardiography

Background and Objectives:The purpose of this study was to analyze the patterns of coronary artery flow, using transthoracic Doppler echocardiography (TTE), in subjects with chest pains and normal coronary angiograms. Subjects and Methods:93 patients (M:F = 34:59, mean age:57±11 years) with chest pains and normal coronary angiograms were included in this study. After obtaining baseline clinical data, an exercise treadmill test (ETT) was performed, according to the Bruce protocol. The peak diastolic coronary artery flow velocity (PDV), at rest, and the coronary flow reserve (CFR), in the distal left anterior descending coronary artery (LAD), were estimated, using dipyridamole, with TTE. After the administration of angiotensin II receptor (AT II) blockers to 12 patients with a CFR <2.1. The ETT and CFR were followed up. Results:Of the 93 subjects 63 (67.7%) were female, and 53 (56.9%) had a history of hypertension and 61 (65.5%) showed ST or T abnormality on their resting ECG. Five subjects (5.3%) had metabolic or hematologic problems, such as hyperthyroidism or anemia. Twenty-seven (30.3%) of the 89 subjects showed a reduced CFR value less than 2.1. The subjects with horizontal or down-sloping ST depression on their ETT showed a decreased CFR, compared with those with no ST shifting or an up-sloping ST depression (p<0.05, respectively). Twenty-six (27.9%) of the 93 subjects showed a slow coronary flow velocity <14 cm/sec, and 15 (83.3%) of 18 subjects who estimated CFR had CFR ≥2.1. In 7 (58.3%) of 12 subjects with a CFR <2.1, their CFR increased, with an improvement of the ETT results, following the administration of the AT II blocker, after an average 19±9 months. Conclusion:The patients with chest pains and normal coronary angiograms have a heterogeneous clinical spectrum, such as hypertensin, slow flow, reduced CFR, and so on. These subjects need treatment according to the etiology and pathogenesis of their condition, which can be followed up by coronary flow measurements, using TTE. (Korean Circulation J 2003;33 (3):205-211)

Verapamil improves the pacing-induced vasodilatation in symptomatic patients with hypertrophic cardiomyopathy

The purpose of the study was to assess the effect of verapamil on the response of diastolic coronary flow velocity and coronary vascular resistance to pacing in symptomatic patients with hypertrophic cardiomyopathy. In 14 patients with hypertrophic cardiomyopathy, the coronary flow velocity was detected in the left anterior descending coronary artery using transthoracic Doppler echocardiography. The peak diastolic coronary flow velocity and coronary vascular resistance was measured at baseline and during pacing. Changes of these parameters induced by the pacing (expressed as the percentage of baseline values) were compared on verapamil treatment and after verapamil withdrawal. The same measurements were obtained in ten control subjects. The results show that, in hypertrophic cardiomyopathy patients, increase in coronary flow velocity during pacing was significantly higher on than off verapamil therapy (64.8±32.5 vs. 41.1±21.3%, P<0.05). In control subjects, pacing-induced increase in coronary flow velocity was comparable to changes in coronary flow velocity in hypertrophic cardiomyopathy patients receiving verapamil (80.2±18.4 vs. 64.8±32.5%, P>0.05). After verapamil withdrawal in hypertrophic cardiomyopathy patients, coronary flow velocity increase during pacing was significantly lower than in control subjects (41.1±21.3 vs. 80.2±18.4%, P<0.05). During pacing the coronary vascular resistance decreased more on verapamil than after drug withdrawal (−34.7±11.7 vs. −24.6±12.9%, P<0.05). In control subjects the coronary vascular resistance decreased during pacing −38.6±6.3% to similar extent as in hypertrophic cardiomyopathy patients on verapamil. We can conclude that endothelium-dependent vasodilatation during pacing was impaired in symptomatic patients with hypertrophic cardiomyopathy. Verapamil treatment was able to restore adequate vasodilator response to pacing stress.

Noninvasive assessment of significant left anterior descending coronary artery stenosis by coronary flow velocity reserve with transthoracic color Doppler echocardiography.

Coronary flow reserve has been considered an important diagnostic index of the functional significance of coronary artery stenosis. With Doppler technique, it has been assessed as the ratio of hyperemic to basal coronary flow velocity (coronary flow velocity reserve [CFVR]) by invasive or semiinvasive methods with a Doppler catheter, a Doppler guide wire, and a transesophageal Doppler echocardiographic probe. Recent technological advancement in transthoracic Doppler echocardiography (TTDE) provides measurement of coronary flow velocity in the distal portion of the left anterior descending coronary artery (LAD) and may be useful in the noninvasive CFVR measurement. The purpose of this study was to evaluate the value of CFVR determined by TTDE for the assessment of significant LAD stenosis. We studied 36 patients who underwent coronary angiography for the assessment of coronary artery disease. The study population consisted of 12 patients with significant LAD stenosis (group A) and 24 patients without significant LAD stenosis (group B). With TTDE, coronary flow velocities in the distal LAD were recorded at rest and during hyperemia induced by intravenous infusion of adenosine (0.14 mg x kg(-1) x min(-1)) under the guidance of color Doppler flow mapping. Adequate spectral Doppler recordings of coronary flow in the distal LAD for the assessment of CFVR were obtained in 34 of 36 study patients (94%). The peak and mean diastolic coronary flow velocities at baseline did not differ between groups A and B (23.6+/-10.3 versus 22.9+/-6.6 cm/s and 16.4+/-8.6 versus 14.5+/-4.0 cm/s, respectively). However, the peak and mean coronary flow velocities during hyperemia in group A were significantly smaller than those in group B (35.6+/-16.3 versus 54.2+/-16.3 cm/s and 24.7+/-13.1 versus 37.9+/-13.0 cm/s, respectively; P<.01). There were significant differences in CFVR obtained from peak and mean diastolic velocity between groups A and B (1.5+/-0.2 versus 2.4+/-0.4 and 1.5+/-0.2 versus 2.6+/-0.4, respectively; P<.001). A CFVR from peak diastolic velocity <2.0 had a sensitivity of 92% and a specificity of 82% for the presence of significant LAD stenosis. A CFVR from mean diastolic velocity <2.0 had a sensitivity of 92% and a specificity of 86% for the presence of significant LAD stenosis. CFVR determined by TTDE is useful in the noninvasive assessment of significant stenotic lesion in the LAD.

Measurement of Coronary Blood Flow Velocity During Handgrip Exercise Using Breath-Hold Velocity Encoded Cine Magnetic Resonance Imaging

Coronary blood flow velocity was measured during handgrip exercise using breath-hold velocity encoded cine magnetic resonance imaging. Peak diastolic coronary flow velocity in the left anterior descending artery was 20.6 ± 9.3 cm/s (mean ± SD) at baseline and increased significantly to 31.1 ± 16.4 cm/s after exercise (50.7 ± 31.3% increase, p <0.01).

Coronary flow reserve: noninvasive measurement in humans with breath-hold velocity-encoded cine MR imaging.

To measure coronary vasodilator reserve with breath-hold velocity-encoded cine magnetic resonance (MR) imaging. Eight healthy adult volunteers underwent 1.5-T MR imaging. Velocity-encoded cine images were acquired at seven to 13 temporal phases in 25 seconds, with k-space segmentation and view-sharing reconstruction (+/- 1 m/sec velocity-encoding value) (repetition time msec/echo time msec = 16/9). Flow velocity in the left anterior descending (LAD) artery was measured twice before and twice after administration of dipyridamole (0.56 mg per kilogram of body weight). Peak diastolic coronary flow velocity in the LAD artery was 14.8 cm/sec +/- 1.9 (mean +/- standard deviation) in the baseline state. It increased significantly (P< .01) to 46.3 cm/sec +/- 10.2 after dipyridamole administration, with an average coronary reserve of 3.14 +/- 0.59. Interstudy and interobserver reproducibilities for measurement of peak diastolic velocity were, respectively, 9.5% +/- 1.6 and 7.0% +/- .2.5 in the baseline state and 6.8% +/- 2.2 and 3.4% +/- 1.5 after dipyridamole administration. Breath-hold velocity-encoded cine MR imaging provided reproducible assessment of coronary flow reserve in humans.

Abnormal coronary flow velocity pattern in patients with left ventricular hypertrophy, angina pectoris, and normal coronary arteries: A transesophageal Doppler echocardiographic study

Previous invasive studies have suggested that coronary flow reserve is impaired in patients with left ventricular hypertrophy (LVH) and symptoms of ischemia. We tested whether transesophageal Doppler, a semiinvasive technique, can detect altered characteristics of baseline coronary blood flow velocity in such patients. Thirty patients with LVH (hypertrophic cardiomyopathy in 4, aortic stenosis in 17, hypertension in 9) were studied. Fourteen patients had asymptomatic LVH. Sixteen patients had clinical symptoms of ischemia with angiographically normal epicardial coronary arteries. Ten subjects with no cardiovascular disease were studied as a control group. Peak diastolic and systolic coronary flow velocities were recorded in the proximal part of the left anterior descending artery (LAD) with the use of pulsed Doppler guided by color flow imaging. Patients with symptomatic LVH had higher diastolic peak coronary flow velocity (81 ± 10 cm/sec, p = 0.0001) compared with normal subjects (41 ± 8 cm/sec) and patients with asymptomatic LVH (44 ± 8 cm/sec). In patients with asymptomatic LVH the diastolic coronary flow velocity/indexed ventricular mass ratio was lower (0.28 ± 0.09 cm/gm/m 2, p = 0.0001) compared with symptomatic patients (0.52 ± 0.12 cm/gm/m 2) and compared with controls (0.47 ± 0.16 cm/gm/m 2). Patients with symptomatic LVH but no aortic stenosis also had higher peak systolic coronary flow velocity (38 ± 9 cm/sec) compared with the other groups ( p = 0.0001). In the group of patients with aortic stenosis a significant inverse linear relation was found between peak systolic coronary flow velocity and peak pressure gradient ( r = −0.60, p = 0.01). In conclusion, patients with symptomatic LVH have abnormally high baseline coronary flow velocities resulting in magnified intimal shear stress. Because flow velocity equals flow/vessel cross-sectional area, it is suggested that high coronary flow velocities in patients with symptomatic LVH result from both augmented coronary flow and failure of the vessel to enlarge commensurately with the increase in LV mass (relative functional stenosis). In patients with aortic stenosis, peak systolic coronary flow velocity appears to be influenced by transvalvular pressure drop.

Noninvasive assessment of coronary flow dynamics before and after coronary angioplasty using transesophageal Doppler

Recent invasive studies using intracoronary Doppler catheters or guide wires reported improved coronary flow dynamics after successful percutaneous transluminal coronary angioplasty. Transesophageal Doppler enables the measurement of coronary flow velocities within the left anterior descending artery. The present study was designed to test: (1) whether transesophageal Doppler may detect coronary flow velocity changes in patients undergoing angioplasty for left anterior descending artery stenosis, and (2) whether this technique may help to evaluate non-invasively the results of the procedure. Twenty-three patients undergoing angioplasty of the left anterior descending artery were studied by transesophageal Doppler before and ≤24 hours after the interventional procedure. Coronary flow velocities were measured in the proximal part of the left anterior descending artery with the use of pulsed Doppler guided by color flow imaging. The degree of stenosis was measured by computerized quantitative coronary arteriography. Coronary flow velocity signals were successfully obtained in 19 of 23 patients (83%). In 16 successful angioplasty procedures, peak diastolic velocity increased from 37 ± 14 cm/s before angioplasty to 51 ± 16 cm/s after (p = 0.0001). In the 3 patients in whom angioplasty was unsuccessful, transesophageal Doppler showed no significant increase in peak diastolic coronary flow velocity. In a total of 19 angioplasty procedures, a good linear relation was found between the percent changes in coronary flow diastolic velocity and the reduction in the degree of stenosis (r = 0.85; p = 0.0001). All patients with >20% increase in peak diastolic velocity had >40% stenosis reduction. Thus, in patients with stenosis of the left anterior descending artery, transesophageal Doppler shows improvement in coronary flow pattern after successful angioplasty. This method may be useful for noninvasive evaluation of angioplasty results in these patients.

Augmentation of coronary blood flow by intra-aortic balloon pumping in patients after coronary angioplasty.

Controversy exists regarding the ability of intra-aortic balloon pumping to increase coronary blood flow in patients with obstructive coronary artery disease. To assess the effects of intra-aortic balloon pumping on coronary hemodynamics, we measured coronary blood flow velocity with a 0.018-in. Doppler-tipped angioplasty guide wire in 15 patients who received an intra-aortic balloon pump for typical clinical indications. Intra-aortic balloon pumping augmented diastolic pressure 83 +/- 35%. In nine patients before angioplasty, peak diastolic coronary flow velocity beyond the stenosis (mean diameter narrowing, 95 +/- 7%) was 5.3 +/- 9.6 cm/sec and was unaffected by intra-aortic balloon pumping. After angioplasty, the improved coronary luminal diameter narrowing (n = 12; mean narrowing, 18 +/- 12%) was associated with increased distal diastolic flow velocity integral and peak diastolic and mean velocities (13.3 +/- 8.4 units: 36.4 +/- 18.3 and 24.0 +/- 11.4 cm/sec, respectively; all p < 0.01 versus before angioplasty), which were further augmented (36 +/- 37%, 54 +/- 49%, and 26 +/- 17%, respectively; all p < 0.01) with intra-aortic balloon pumping. Intra-aortic balloon pumping did not significantly increase the distal systolic velocity integral (10 +/- 59%) or peak systolic velocity (3 +/- 33%). Similar degrees of balloon pump augmentation of distal coronary flow velocity values were observed in five angiographically normal reference arteries in four patients. These data demonstrate lack of significant flow improvement beyond most critical stenoses with intra-aortic balloon pumping and the unequivocal restoration and intra-aortic balloon pump-mediated augmentation of both proximal and distal coronary blood flow velocities after amelioration of severe coronary obstructions in patients after successful coronary angioplasty.

Observations of coronary flow augmentation and balloon function during intraaortic balloon counterpulsation using transesophageal echocardiography

The intraaortic balloon pump has been shown to decrease myocardial oxygen demand by afterload reduction, while increasing myocardial oxygen supply by diastolic augmentation of coronary blood flow. This diastolic augmentation of coronary flow has been demonstrated experimentally with invasive methods. Noninvasively, transesophageal echocardiography has demonstrated efficacy in enabling visualization of the proximal left coronary artery and in recording coronary blood flow velocity. To assess the potential of this technique in demonstrating quantitatively the increase in coronary flow during counterpulsation, 6 patients were studied during intermittent balloon pumping. Peak diastolic coronary blood flow velocity increased by a mean of 117% (range 62 to 287) during balloon inflation (p = 0.002). Furthermore, coronary flow velocity integral increased by a mean of 87% (range 43 to 176; p = 0.003). Problems associated with intraaortic balloon pumping were discovered by transesophageal echocardiography in 4 patients (incorrect balloon placement, damage to the aortic wall [2 patients], and premature balloon deflation time). Transesophageal echocardiography can be used in evaluating intraaortic balloon positioning within the aorta and in monitoring coronary artery flow augmentation during counterpulsation. This relatively noninvasive technique adds another dimension to the evaluation of balloon function and may help in optimizing the benefits of counterpulsation.