Comparison of relative coronary Doppler flow velocity reserve to stress myocardial perfusion imaging in patients with coronary artery disease.

To compare relative coronary artery vasodilator reserve (rCVR = CVRtarget/CVRreference) to myocardial perfusion stress imaging, 48 patients with coronary artery stenoses (61% +/- 16%; mean, +/- SD; range, 30%-91%) had measurements of target and reference vessel CVR (Doppler-tipped guidewire). rCVR was computed and compared to stress 201thallium or (99m)technetium-sestamibi myocardial tomography. Compared to 24 patients with negative stress imaging studies, 24 patients with positive stress studies had angiographically more severe stenoses (74% +/- 13% vs. 44% +/- 24%; P = 0.0005) with lower CVR(target) (1.68 +/- 0.55 vs. 2.46 +/- 0.74; P = 0.002) and lower rCVR (0.72 +/- 0.22 vs. 1.0 +/- 0.26; P < 0.003). Based on receiver-operator characteristic (ROC) cut points (CVR > 1.9; rCVR > 0.75), compared to CVR, rCVR had similar agreement (Kappa 0.54 vs. 0.50), sensitivity (63% vs. 71%), specificity (88% vs. 83%), and positive predictive value (83% vs. 81%) with myocardial perfusion tomography. A concordant CVRtarget/rCVR only slightly increased sensitivity, specificity, and positive predictive values (77%, 90%, and 87%, respectively). Although rCVR, like CVR, correlates with stress myocardial perfusion imaging results, rCVR did not have significant incremental prognostic value over CVR alone for myocardial perfusion imaging. However, rCVR does provide additional information regarding the status of the microcirculation in patients with coronary artery disease and complements the CVR for lesion assessment.

Coronary angiography using 4 Fr catheters with acisted power injection: A randomized comparison to 6 Fr manual technique and early ambulation.

Coronary angiography using 4 Fr catheters may reduce access site complications, promote better utilization of outpatient facilities, but at a cost of suboptimal image quality. To determine whether 4 Fr diagnostic angiography with power injection (Acist, Minneapolis, MN) was equivalent to 6 Fr manual technique, 101 unselected patients were randomized to transfemoral coronary angiography with 4 or 6 Fr catheters. Procedural characteristics, angiographic quality scores, and results of 90 min ambulation were analyzed. Coronary angiographic quality scores using 4 Fr and 6 Fr catheters were equivalent (left coronary artery 4.73 +/- 0.6 vs. 4.80 +/- 0.65, P = 0.28; right coronary artery 4.98 +/- 90.13 vs. 4.97 +/- 0.16, P = 0.48). However, 4 Fr left ventriculographic image score was lower (4.53 +/- 0.68 vs. 4.83 +/- 0.42, P = 0.0002), attributed, in part, to a smaller injected contrast volume (32 +/- 11 vs. 37 +/- 4 mL, P = 0.001). The total study contrast volume was significantly less in the 4 Fr group (119 +/- 35 vs. 159 +/- 52 mL, P = 0.001). Complications related to early ambulation at 90 min were similar and minimal in both groups. Compared to 6 Fr manual contrast injection technique, diagnostic angiography through 4 Fr catheters with power contrast injection resulted in equivalent coronary angiographic image quality, slightly reduced but diagnostic left ventricular image quality, and significantly less contrast volume. Four Fr angiography facilitates early ambulation without compromising safety and image quality.

Abnormal coronary flow velocity reserve after coronary artery stenting in patients: role of relative coronary reserve to assess potential mechanisms.

BACKGROUND: Absolute coronary flow velocity reserve (CVR) after stenting may remain abnormal as a result of several different mechanisms. Relative CVR (rCVR=CVR(target)/CVR(reference)) theoretically normalizes for global microcirculatory disturbances and facilitates interpretation of abnormal CVR. METHODS AND RESULTS: To characterize potential mechanisms of poststent physiology, CVR was measured using a Doppler-tipped angioplasty guidewire in 55 patients before and after angioplasty, after stenting, and in an angiographically normal reference vessel. For the group, the percent diameter stenosis decreased from 75+/-13% to 40+/-18% after angioplasty and to 10+/-9% (all P<0.05) after stent placement. After angioplasty, CVR increased from 1.63+/-0.71 to 1.89+/-0.55 (P<0.05) and after stent placement, to 2.48+/-0.75 (P<0.05 versus pre- and postangioplasty). After angioplasty, rCVR increased from 0.64+/-0.26 to 0.75+/-0.23 and after stent placement to 1.00+/-0.34. In 17 patients with CVR(stent) < or = 2.0, increased basal coronary flow, rather than attenuated hyperemia, was responsible in large part for the lower CVR(stent) compared with patients having CVR(stent) >2.0. In 8 patients with CVR(stent) <2.0, a normal rCVR supported global microvascular disease. The subgroup of 9 patients with CVR(stent) <2.0 and abnormal rCVR (16% of the studied patients) may require a pressure-derived fractional flow reserve to differentiate persistent obstruction from diffuse atherosclerotic disease or microvascular stunning. CONCLUSIONS: Although a majority of patients after stenting normalize CVR for the individual circulation (ie, normal CVR or normal rCVR), in those with impaired CVR(stent), the analysis of coronary flow dynamics suggests several different physiological mechanisms. Additional assessment may be required to fully characterize the physiological result for such patients to exclude remediable luminal abnormalities.

Heterogeneity of coronary flow reserve in the examination of multiple individual allograft coronary arteries.

BACKGROUND: Epicardial and resistance vessel function in the transplanted heart has been evaluated primarily in regions supplied by a single vessel. Heterogeneity of flow among multiple perfusion fields as a marker of early endothelial dysfunction in the microcirculation has not been evaluated previously. This study tested the hypothesis that increased variability of coronary flow reserve (CFR) among multiple vascular regions would be associated with allograft coronary vasculopathy. METHODS AND RESULTS: One hundred six posttransplant patients undergoing cardiac catheterization had measurement of CFR in at least 3 major epicardial vessels. Patients were divided into those with minimal angiographic abnormalities (n=37) and those with no angiographic abnormalities (n=69). The ranges, coefficients of variation, and univariate and multivariate regression analyses of CFR were computed to determine the major clinical factors influencing the degree of variability. The abnormal angiographic group was older (54+/-11 versus 47+/-13 years; P<0.003), had older hearts (35+/-11 versus 27+/-10 years; P<0.005), and were further posttransplant (1626+/-1022 versus 931+/-984 days; P<0.0009). There was no difference in global CFR between groups (normal, 3.4+/-0.8 versus abnormal, 3.4+/-0.7; P=NS). The coefficient of variation of CFR was higher for the abnormal group (16.3+/-8.6% versus 11.0+/-5.5%; P<0. 0006). Univariate and multivariate predictors of increased variability in CFR included angiographic abnormalities, patient age, and body mass index. Both angiographic abnormalities and an elevated CV of CFR were predictive of a combined end point of death, congestive heart failure, or subsequent development of >/=50% coronary stenosis. CONCLUSIONS: These data demonstrate that increased variability of CFR is associated with discernible allograft coronary arteriopathy and is predictive of outcome in patients after heart transplantation.

Cardiopulmonary exercise testing identifies low risk patients with heart failure and severely impaired exercise capacity considered for heart transplantation.

OBJECTIVES: The 3-year survival rates of 500 patients with congestive heart failure (CHF) referred for heart transplantation were assessed to evaluate the clinical and exercise variables most useful for estimating prognostic risk. BACKGROUND: Detailed prognostic risk stratification of patients with a peak exercise oxygen consumption (VO2) < or = 14 ml/min per kg to identify lower risk patient subsets has been limited in earlier series by relatively small sample size. METHODS: Cardiopulmonary exercise testing was performed in 500 patients with CHF referred for heart transplantation; 154 (31%) had a peak exercise VO2 < or = 14 ml/min per kg. Univariate and multivariate analyses were performed to identify the 3-year prognostic risk. RESULTS: The 55% 3-year survival rate of the 77 patients with a peak exercise VO2 < or = 14 ml/min per kg unable to reach a peak exercise systolic blood pressure (SBP) of 120 mm Hg was significantly lower than the 83% survival rate in the 74 patients able to reach this exercise blood pressure (p = 0.004). Multivariate analysis revealed that peak exercise SBP (p = 0.0005) and percent predicted peak VO2 < or = 50% (p = 0.04) were the two most important predictors for the combined end point of death or listing as Status 1. CONCLUSIONS: Peak exercise SBP and percent predicted peak exercise VO2 are two inexpensive and easily measured noninvasive variables that can be used to further prognostically risk stratify ambulatory patients with CHF referred for heart transplantation with a peak exercise VO2 < or = 14 ml/min per kg.

Role of coronary artery lumen enlargement in improving coronary blood flow after balloon angioplasty and stenting: a combined intravascular ultrasound Doppler flow and imaging study.

OBJECTIVES: This study sought to examine the mechanism of increasing coronary flow reserve after balloon angioplasty and stenting. BACKGROUND: Coronary vasodilatory reserve (CVR) does not improve after percutaneous transluminal coronary angioplasty in > or = 50% of patients, postulated to be due to impaired microvascular circulation or inadequate lumen expansion despite adequate angiographic results. METHODS: To demonstrate the role of coronary lumen expansion, serial coronary flow velocity (0.014-in. Doppler guide wire) was measured in 42 patients before and after balloon angioplasty and again after stent placement. A subset (n = 17) also underwent intravascular ultrasound (IVUS) imaging of the target sites after angioplasty and stenting. CVR (velocity) was computed as the ratio of adenosine-induced maximal hyperemic to basal average peak velocity. RESULTS: The percent diameter stenosis decreased from (mean +/- SD) 84 +/- 13% to 37 +/- 18% after angioplasty and to 8 +/- 8% after stenting (both p < 0.05). CVR was minimally changed from 1.70 +/- 0.79 at baseline to 1.89 +/- 0.56 (p = NS) after angioplasty but increased to 2.49 +/- 0.68 after stent placement (p < 0.01 vs. before and after angioplasty). IVUS lumen cross-sectional area was significantly larger after stenting than after angioplasty (8.39 +/- 2.09 vs. 5.10 +/- 2.03 mm2, p < 0.05). Anatomic variables were related to increasing coronary flow velocity reserve (CVR vs. IVUS lumen area: r = 0.47, p < 0.005; CVR vs. quantitative coronary angiographic percent area stenosis: r = 0.58, p < 0.0001). CONCLUSIONS: In most cases, increases in CVR were associated with increases in coronary lumen cross-sectional area. These data suggest that impaired CVR after angioplasty is often related to the degree of residual narrowing, which at times may not be appreciated by angiography. A physiologically complemented approach to balloon angioplasty may improve procedural outcome.

Long-term cardiopulmonary exercise performance after heart transplantation.

Functional capacity is an important outcome variable for heart transplantation, but there are few data that examine the temporal relation and duration of improvement in cardiopulmonary exercise performance after cardiac transplantation. Cardiopulmonary exercise performance was measured in 140 patients who underwent 426 treadmill exercise tests up to 9 years after cardiac transplantation. Univariate and multivariate analyses were used to predict postoperative improvement in functional capacity. Peak oxygen consumption (VO2) significantly improved from 14.2 +/- 3.7 ml/min/kg before to 21.4 +/- 5.6 ml/min/kg at a mean of 11.2 +/- 3.0 months after the transplant procedure (p < 0.001). When peak aerobic capacity was compared with a normal population, peak VO2 was < 50% of predicted in only 9 patients (12%), from 50% to 70% in 34 patients (44%), from 70% to 90% of predicted in 24 patients (31%); 10 patients (13%) were able to achieve > 90% of peak predicted VO2. The improvement seen at 6 months did not significantly change over 9 years of follow-up. Significant preoperative univariate predictors of.1-year postoperative improvement in peak VO2 were preoperative peak VO2 (p = 0.004), age (p < 0.001), ischemic cardiomyopathy (p = 0.007), and preoperative left ventricular ejection fraction (p < 0.001). Peak VO2 at 1 year in patients able to perform the test was not significantly influenced by acute rejection episodes, donor body surface area, or donor/recipient size ratio. In conclusion, exercise capacity is significantly improved within 6 months after cardiac transplantation, and maintained as long as 9 years after procedure. The magnitude of postoperative improvement is inversely related to preoperative peak VO2 and age.

Assessment of blood flow distal to coronary artery stenoses. Correlations between myocardial positron emission tomography and poststenotic intracoronary Doppler flow reserve.

BACKGROUND: Previous studies have correlated quantitative coronary angiographic stenosis severity with positron emission tomography (PET) myocardial perfusion and proximal measurements of intracoronary flow velocities in normal and diseased coronary arteries. The aim of this study was to correlate regional myocardial blood flow (RMBF) derived from [15O]H2O PET with directly measured poststenotic intracoronary Doppler flow velocity data acquired under basal conditions and dipyridamole-induced hyperemia. METHODS AND RESULTS: Eleven consecutive patients 53 +/- 13 years old with ischemic chest pain and isolated proximal left coronary artery stenoses (left anterior descending, 9; left circumflex, 2; mean, 59 +/- 23% diameter stenosis) underwent [15O]H2O myocardial PET and intracoronary Doppler flow velocity studies within 1 week. PET RMBF (mL.g-1.min-1) and myocardial perfusion reserve (MPR) were calculated in poststenotic and normal reference vascular beds. Poststenotic Doppler average peak flow velocities (APV; cm/s) and coronary flow velocity reserve (CFR) were compared with corresponding PET data and quantitative angiographic lesional parameters. PET RMBF and Doppler APV were linearly correlated (r = .60; P < .001), as were poststenotic PET MPR and Doppler CFR (r = .76; P < .0002). Relative coronary flow velocity and MPR ratios between poststenotic and angiographically normal vascular beds were comparably reduced (0.83 +/- 0.25 versus 0.86 +/- 0.21, respectively; P = NS). CONCLUSIONS: Intracoronary Doppler flow velocities acquired distal to isolated left coronary artery stenoses correlated with [15O]H2O PET regional myocardial perfusion and are useful for assessment of the physiological significance of coronary stenoses in humans.

Determination of angiographic (TIMI grade) blood flow by intracoronary Doppler flow velocity during acute myocardial infarction.

BACKGROUND: This study compared angiographically graded coronary blood flow with intracoronary Doppler flow velocity in patients during percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction. Different TIMI angiographic flow grades (flow grades based on results of the Thrombolysis in Myocardial Infarction trial) have been associated with different clinical results after reperfusion for acute myocardial infarction. However, intracoronary blood flow velocity has not been compared with the angiographic method of determining flow grade in patients. METHODS AND RESULTS: Coronary flow velocity (measured by use of a Doppler guidewire) during primary or rescue PTCA in 41 acute myocardial infarction patients was compared with TIMI grade and cineframes-to-opacification count. Before PTCA, 34 patients had TIMI grade 0 or 1, 5 had TIMI grade 2, and 2 had TIMI grade 3 flow in the infarct artery. Flow velocity was similar among patients with TIMI grades 0, 1, or 2 but was lower than in those with TIMI grade 3 flow (9.4 +/- 5.4 versus 16.0 +/- 5.4 cm/s for TIMI grades < or = 2 versus TIMI grade 3, respectively; P < .05). After PTCA, 1 patient had TIMI grade 1, 5 had TIMI 2, and 35 had TIMI 3 flow. Poststenotic flow velocity increased from 6.6 +/- 6.1 to 20.0 +/- 11.1 cm/s (P < .01). TIMI grade 3 flow increased to 21.8 +/- 10.9 cm/s (P < .05 versus before PTCA). Although post-PTCA flow velocity correlated with angiographic cineframes-to-opacification count (r = .45; P < .02) for TIMI grade 3, there was a large overlap with TIMI grades < or = 2 that had low flow velocity (< 20 cm/s). Nine of 11 clinical events (unstable angina and coronary artery bypass graft surgery) occurred in patients with low coronary flow velocity. CONCLUSIONS: Determination of flow velocity after reperfusion may enhance patient characterization and provide the physiological rationale for clinical variations after reperfusion therapy.

Differential characterization of human coronary collateral blood flow velocity.

The functional importance and protective nature of the coronary collateral circulation has been well established. There are few data, however, regarding the phasic nature and absolute velocities of collateral flow in patients. The aim of this study was to characterize and quantify ipsilateral coronary collateral blood flow velocity in patients during coronary angioplasty. Coronary collateral flow velocity was measured in 49 patients during coronary angioplasty. Angiographic collateral filling was categorized by the Rentrop grading scale (0 to 3) and by anatomic pathway (epicardial, intramyocardial, or unknown [acutely recruited]). Collateral blood flow velocity was measured with a Doppler-tipped guide wire placed distal to the balloon occlusion in the collateralized vessel. Collateral flow velocity was characterized as predominantly systolic or diastolic, and phasic flow patterns were defined as biphasic (both systolic and diastolic), monophasic (only systolic or diastolic), or bidirectional (antegrade and retrograde velocity). Twenty-three (47%) patients had biphasic flow; 17 (35%) patients had monophasic flow; and 9 (18%) patients had bidirectional flow. Thirty-six (73%) of 49 patients had predominantly systolic flow signals. Epicardial collateral pathways had the highest total flow velocity integral, at 15.0 +/- 7.0 (vs intramyocardial [8.4 +/- 5.7] and acutely recruitable [5.4 +/- 2.1]; p < 0.05). There were no differences in flow velocity integrals among the Rentrop angiographic grades of collateral filling. These data establish three patterns of coronary collateral blood flow and demonstrate that the majority of collateral flow in the ipsllateral receiving vessel occurs during systole. The measurement of coronary collateral flow velocity provides a unique means to study the effects of pharmacologic or mechanical interventions on human collateral blood flow.

Correlation of poststenotic hyperemic coronary flow velocity and pressure with abnormal stress myocardial perfusion imaging in coronary artery disease.

The functional significance of coronary stenoses is frequently determined by adjunctive noninvasive myocardial perfusion imaging. Poststenotic coronary flow velocity and pressure can be measured directly during routine cardiac catheterization. The aim of this study was to correlate poststenotic (distal) flow velocity and pressure with stress perfusion imaging in patients. Quantitative angiography, basal and hyperemic transstenotic coronary flow velocities, and pressure gradients were measured in 50 patients within 1 week of exercise (n = 29) or of pharmacologic (n = 21) stress perfusion imaging. Twenty-two of 25 patients (88%) with reversible perfusion abnormalities had diminished distal coronary flow velocity reserves (CFVR) of < or = 2.0 x baseline, whereas 22 of 25 (88%) with normal perfusion imaging studies had a normal distal CFVR of > 2.0 (p = 0.000 1). Thirteen of 25 patients (52%) with reversible perfusion abnormalities had transstenotic gradients > or = 20 mm Hg, whereas 20 of 25 (80%) with normal perfusion studies had gradients <20 mm Hg (p = 0.01). Quantitative angiography did not differentiate patients with normal versus abnormal myocardial perfusion imaging. Distal CFVR was correlated more significantly with myocardial perfusion imaging results (kappa = 0.76) than with pressure gradients (kappa = 0.32). Exercise and pharmacologic stress myocardial perfusion imaging abnormalities reflect diminished post-stenotic coronary flow to a greater degree than transstenotic pressure gradients.

The surgical management of allograft coronary disease: a paradigm shift.

The surgical options for heart transplant recipients who develop obstructive coronary artery disease in their allograft have historically been limited to retransplantation. Given the worse outcome in recipients of second grafts, often caused by recurrence of coronary disease, coupled with the significant increase in the number of patients on the transplantation waiting lists, has made retransplantation a limited option. However, as heart transplant recipients continue to live longer, there are an increasing number of patients who develop allograft coronary disease. Coronary bypass surgery has not been offered to these patients because of numerous pathology reports describing uniform involvement of the coronary vessel from its origin to the distal intramural branches, thereby eliminating any reasonable runoff vascular bed to handle increased flow that might be delivered with bypass conduits. However, new diagnostic techniques such as measurement of coronary flow reserve by Doppler flow wire can define the physiological vasodilating capacity or reserve which, if normal, should allow conventional bypass surgery if adequate target epicardial vessels are present. This approach would allow a more reasonable alternative to many patients who otherwise would die of this disease without any intervention. Other alternatives such as transmyocardial laser revascularization are discussed.

Influence of percutaneous transluminal coronary rotational atherectomy with adjunctive percutaneous transluminal coronary angioplasty on coronary blood flow.

The purpose of this study was to examine the influence of sequential percutaneous transluminal coronary rotational atherectomy (PTCRA) and coronary angioplasty on coronary blood flow reserve in patients. Rotational coronary atherectomy restores lumen patency by partially ablating fibrocalcific plaque, releasing microparticulate debris into the distal coronary circulation. Adjunctive balloon angioplasty is usually performed to optimize the angiographic luminal dimensions. Serial alterations in coronary physiology have not been reported. Fourteen lesions in 13 patients were treated by sequential rotational atherectomy followed by adjunctive balloon angioplasty. Poststenotic baseline coronary blood flow velocity was measured by using a Doppler flow wire (FloWire, Cardiometrics, Inc., Mountain View, Calif.), and coronary blood flow was calculated by using the distal vessel cross-sectional area obtained by quantitative coronary angiography. Data were acquired at baseline and during hyperemia (12 to 18 microg of intracoronary adenosine), before and after PTCRA, and again after balloon angioplasty. The mean stenosis decreased from 76 percent +/- 12 percent at baseline to 21 percent +/- 11 percent at the completion of the procedure (p<0.01). The minimal luminal diameter (by quantitative coronary angiography) was 0.7 +/- 0.4 mm at baseline, increased to 1.9 +/- 0.4 mm after rotational atherectomy (p<0.01), and increased to 2.4 +/- 0.5 mm after balloon angioplasty (p<0.01 versus baseline and PTCRA). Distal (poststenotic) coronary blood flow at baseline was 47 +/- 23 ml/min and 57 +/- 38 ml/min during hyperemia. After PTCRA, coronary blood flow increased to 104 +/- 59 ml/min and to 132 +/- 73 ml/min with hyperemia. After adjunctive angioplasty, coronary blood flow was 84 +/- 40 ml/min (p=not significant [NS] vs PTCRA) and increased to 143 +/- 81 ml/min with hyperemia (p=NS vs PTCRA). The poststenotic coronary flow reserve increased from an initial value of 1.1 +/- 0.2 ml/min to 1.3 +/- 0.3 ml/min after PTCRA (p=NS vs baseline) and to 1.6 +/- 0.3 ml/min after adjunctive balloon angioplasty (p<0.01 vs p=NS vs PTCRA). PTCRA significantly increased resting coronary blood flow. Adjunctive balloon angioplasty did not significantly augment resting or hyperemic coronary blood flow more than that achieved by rotational atherectomy alone. These data demonstrate that PTCRA alone improves baseline coronary blood flow with minimal additional physiologic change after adjunctive balloon angioplasty.

Influence of intimal thickening on coronary blood flow responses in orthotopic heart transplant recipients. A combined intravascular Doppler and ultrasound imaging study.

BACKGROUND: Intravascular ultrasound imaging detects epicardial intimal thickening in the majority of heart transplant recipients with angiographically normal epicardial coronary arteries. Although coronary artery vasoreactivity is abnormal after cardiac transplantation, intimal thickening does not appear to affect conduit vessel responses. However, the effect of intimal thickening on both conduit and resistance vessel responses, as measured by changes in volumetric coronary blood flow (CBF), is unknown. METHODS AND RESULTS: Epicardial coronary artery conductance and microvascular resistance vessel responses were studied after intracoronary adenosine and nitroglycerin administration in 36 orthotopic heart transplant recipients 1 month to 7 years after transplantation. Sequentially measured coronary flow average peak velocity ([APV, cm/s] 0.018 in Doppler guide wire) and epicardial luminal cross-sectional area ([CSA, mm2] 4.3F 30-MHz ultrasound catheter) data were obtained at baseline and during peak hyperemia after administration of 12 to 18 micrograms IC adenosine and 150 to 200 micrograms IC nitroglycerin. Volumetric CBF (mL/min) was calculated as CBF = APV (cm/s) x CSA (mm2) x 60 seconds/1 min x 1 cm2/100 mm2 x 0.5. Measurements were made from a discrete position in the proximal left anterior descending (LAD) artery (n = 22), mid-LAD artery (n = 7), proximal circumflex artery (n = 6), and proximal right coronary artery (n = 1). Intimal thickening was present in 19 of 32 patients (60%). Both adenosine and nitroglycerin increased APV (from 18.9 +/- 4.9 to 56.0 +/- 11.5 cm/s for adenosine and from 20.2 +/- 5.3 to 49.1 +/- 11.5 cm/s for nitroglycerin; both P < .05). Coronary flow velocity reserve was significantly higher for adenosine compared with nitroglycerin (3.1 +/- 0.6 versus 2.5 +/- 0.7, respectively; P < .001). Epicardial luminal CSA was unchanged during adenosine hyperemia compared with baseline (17.4 +/- 3.8 versus 17.3 +/- 4.0 mm2, respectively; P = NS) but was significantly greater during nitroglycerin hyperemia compared with baseline (18.7 +/- 3.8 versus 17.3 +/- 4.0 mm2, 6.2 +/- 3.6% change; P < .05). Baseline CBF was similar before drug administration. Hyperemic adenosine and nitroglycerin CBF responses (297 +/- 99 and 276 +/- 87 mL/min, respectively; P = NS) and CBF reserve (3.0 +/- 0.7 and 2.7 +/- 0.7, respectively; P = NS) were not significantly different. Importantly, intimal thickening did not diminish resting or hyperemic APV, coronary flow velocity reserve, luminal CSA, CBF, or CBF reserve responses. CONCLUSIONS: In this study of angiographically normal heart transplant recipients, epicardial intimal thickening does not diminish conduit and resistance vessel responses during endothelial-independent vasodilator administration.

Comparison of pressure-derived fractional flow reserve with poststenotic coronary flow velocity reserve for prediction of stress myocardial perfusion imaging results.

The physiologic importance of coronary stenoses can be assessed indirectly by stress myocardial perfusion imaging or directly by translesional pressure and flow measurements. The aims of this study were to compare myocardial fractional flow reserve (FFRmyo), a recently proposed index of lesion significance derived from hyperemic translesional pressure gradients, with directly measured poststenotic flow velocity reserve for the prediction of myocardial perfusion stress imaging results in corresponding vascular beds. Poststenotic coronary flow velocity (0.018-inch guide wire) and translesional pressure gradients (2.7F fluid-filled catheter) were measured at baseline and after intracoronary adenosine (12 to 18 micrograms) in 70 arteries (diameter stenosis: mean 56% +/- 15%, range 14% to 94% by quantitative angiography). Coronary flow reserve was calculated as the ratio of hyperemic to basal mean flow velocity. FFRmyo was calculated during maximal hyperemia as equal to 1-(hyperemic gradient [mean aortic pressure-5]), where 5 is the assumed central venous pressure. Positive and negative predictive values and predictive accuracy for reversible stress myocardial perfusion abnormalities were computed. There was a significant correlation between pressure-derived FFRmyo and distal coronary flow reserve (r = 0.46; p < 0.0001). The strongest predictor of stress myocardial perfusion imaging results was the poststenotic coronary flow reserve (chi square = 33.2; p < 0.0001). The correlation between stress myocardial perfusion imaging and FFRmyo was also significant (chi square = 8.3; p < 0.005). There was no correlation between stress myocardial perfusion imaging and percentage diameter stenosis (chi square = 2.9; p = 0.10) or minimal lumen diameter (chi square = 0.47; p = 0.73). A poststenotic coronary flow reserve of < or = 2 had a positive predictive value of 89% for regionally abnormal myocardial perfusion imaging abnormalities, whereas the positive predictive values of FFRmyo and angiographic percentage diameter stenosis were only 71% and 67% respectively. In conclusion, the predictive value of poststenotic coronary flow velocity reserve for stress-induced myocardial perfusion abnormalities exceeds that of the translesional FFRmyo. These findings should be considered when applying these techniques for clinical decision making in the assessment of coronary stenosis severity.

Quantification of collateral blood flow during PTCA by intravascular Doppler.

The assessment of flow velocity using the Doppler guidewire provides a means of investigating both antegrade and retrograde blood flow in the coronary artery distal to obstructive lesions and occluding PTCA balloons. This has yielded unique qualitative and quantitative information regarding coronary collateral blood flow, and the responses of collaterals to pharmacological and haemodynamic perturbations. The current study analysed collateral flow velocity recordings obtained during coronary interventions in 46 patients in our laboratory. The mean collateral peak velocity integral distal to the occluding PTCA balloon was 9 +/- 7 units, while antegrade distal coronary peak velocity integral following stenosis relief by PTCA was 27 +/- 12 units. Thus, during PTCA balloon occlusion collaterals were able to supply a mean of 30 +/- 18% of the flow provided antegrade by successful PTCA. Variability in collateral flow velocity was not accounted for by differences in the PTCA artery assessed, the supply artery, the direction of collateral filling, the severity of coronary stenosis, or the angiographic grade of collaterals, and the magnitude of collateral flow velocity did not correlate with preserved left ventricular regional wall motion. The measurement of collateral flow velocity by intravascular Doppler provides unique and quantitative information regarding the coronary collateral circulation.

Patterns of phasic coronary collateral flow velocity in patients.

Antegrade or retrograde collateral flow velocity Doppler signals, acquired with the flowire, permit the quantitation of collateral blood flow and its phasic patterns. The velocity spectra are easily visualized, and reproducible alterations during balloon occlusion may be directly related to coronary collateral flow-dependent variables of ischemia and left ventricular wall motion. The effects of pharmacologic stimulation on collateral flow remain under study.

Assessment of transplant arteriopathy by intracoronary two-dimensional ultrasound imaging and coronary flow velocity.

Transplant coronary arteriopathy is the major impediment to the long-term survival of cardiac allografts. This report highlights two-dimensional imaging and Doppler flow to assess transplant coronary arteriopathy.