Intracoronary Flow Research Articles

Response to Letter Regarding Article, “Assessment of Microcirculatory Remodeling With Intracoronary Flow Velocity and Pressure Measurements: Validation With Endomyocardial Sampling in Cardiac Allografts”

Response to Letter Regarding Article, “Assessment of Microcirculatory Remodeling With Intracoronary Flow Velocity and Pressure Measurements: Validation With Endomyocardial Sampling in Cardiac Allografts”

Letter by Hiemann et al Regarding Article, “Assessment of Microcirculatory Remodeling With Intracoronary Flow Velocity and Pressure Measurements: Validation With Endomyocardial Sampling in Cardiac Allografts”

We thank Hiemann et al for their interest in our work.1 In their letter, they suggest that immunostaining for CD34, a marker of endothelial cells, should not be used for assessment of capillary density unless concomitant α-actin immunostaining is performed. In our research, capillaries were tagged and counted by 2 experienced pathologists in CD34-stained biopsy samples; microvessels and arterioles with stained …

The Prognostic Value of Combined Fractional Flow Reserve and TIMI Frame Count Measurements in Patients with Stable Angina Pectoris and Acute Coronary Syndrome

The aim of this study was to evaluate the prognostic value of different fractional flow reserve (FFR) cutoff values and corrected thrombolysis in myocardial infarction frame (TIMI) count (CTFC) measurements in a series of consecutive patients with moderate coronary lesions, including patients with unstable angina, myocardial infarction, and/or positive noninvasive functional test findings. We included 162 consecutive coronary patients in whom revascularization of a moderate coronary lesion was deferred based on a FFR value ≥0.75. Patients were divided according to the results of the intracoronary pressure and flow measurements into four groups: group A: 0.75 ≤ FFR ≤ 0.85 and CTFC > 28 (n=22), group B: 0.75 ≤ FFR ≤ 0.85 and CTFC ≤ 28 (n = 55), group C: 0.85 < FFR and CTFC > 28 (n = 19), and group D: 0.85 < FFR and CTFC ≤ 28 (n = 66). Adverse cardiac events and the presence of angina were evaluated at follow-up. At a mean follow-up of 18 ± 10 months, cardiac event rate in patients with 0.75 ≤ FFR ≤ 0.85 and FFR > 0.85 were 22% and 9%, respectively (P = 0.026) and also, a trend was observed toward a higher cardiac event rate in case of an abnormal CTFC (CTFC > 28) compared to a normal CTFC (24% vs 12%, P = 0.066). Furthermore, a significantly higher cardiac event rate was observed when group A was compared to group D (31.8% vs 7.6%, respectively, P = 0.004). Patients with potential microvascular dysfunction and borderline FFR values should be interpreted with caution, and management strategies should be guided not only by pressure measurement, but also by possibly supplementary clinical risk stratification and noninvasive tests.

International Society for Heart and Lung Transplantation working formulation of a standardized nomenclature for cardiac allograft vasculopathy—2010

The development of cardiac allograft vasculopathy remains the Achilles heel of cardiac transplantation. Unfortunately, the definitions of cardiac allograft vasculopathy are diverse, and there are no uniform international standards for the nomenclature of this entity. This consensus document, commissioned by the International Society of Heart and Lung Transplantation Board, is based on best evidence and clinical consensus derived from critical analysis of available information pertaining to angiography, intravascular ultrasound imaging, microvascular function, cardiac allograft histology, circulating immune markers, non-invasive imaging tests, and gene-based and protein-based biomarkers. This document represents a working formulation for an international nomenclature of cardiac allograft vasculopathy, similar to the development of the system for adjudication of cardiac allograft rejection by histology.

Relationship between Strain Rate Imaging and Coronary Flow Reserve in Assessing Myocardial Viability after Acute Myocardial Infarction

To evaluate the relationship between strain rate (SR) imaging and coronary flow reserve (CFR) in assessing viability of akinetic myocardium after acute myocardial infarction (MI). Forty patients with acute first ST-elevation MI were analyzed. SR imaging and CFR by intracoronary flow measurement were obtained on the same day, 3~5 days after primary percutaneous coronary intervention. Viability of the akinetic myocardium was determined on 6-week echocardiography. Systolic SR (SRs, -0.42 ± 0.10 vs. -0.35 ± 0.11 per second, P = 0.03), early diastolic SR (SRe, 0.68 ± 0.31 vs. 0.41 ± 0.22 per second, P = 0.003), and systolic strain (Ss, -5.9 ± 3.4 vs. -2.5 ± 4.0%, P = 0.04) were greater in akinetic, but viable myocardium of 21 patients than in akinetic and nonviable myocardium of 19 patients. CFR was also higher in patients with akinetic, but viable myocardium (2.0 ± 0.5 vs. 1.5 ± 0.5, P < 0.001). SRs, SRe, and Ss were significantly related to CFR (r =-0.50, r = 0.58, r =-0.56, respectively, all P ≤ 0.001) and SRe was most related to CFR (P < 0.001). The sensitivity and specificity to predict myocardial viability were 85.7% and 68.4% for CFR (cutoff = 1.75), and 90.5% and 57.9% for SRe (cutoff = 0.37 per second), respectively. The degree of myocardial deformation determined by SR imaging was related to the degree of microvascular integrity determined by CFR, and can be used as a noninvasive method to predict myocardial viability after acute MI.

Complete Atrioventricular Block Was Improved by a Coronary Artery Active Perfusion System in Off-Pump Coronary Artery Bypass Graft Surgery

m p OFF-PUMP CORONARY ARTERY bypass graft (OPCAB) surgery usually requires temporary coronary occlusion uring anastomosis of the vascular graft to the target vessel. To revent myocardial ischemia-related events such as hypotenion and arrhythmias, an intracoronary shunt often is used. owever, ischemia still can occur if there is severe hypotension aused by insufficient intracoronary shunt flow. The coronary rtery active perfusion system (CAPS) is an active perfusion ystem through which oxygenated blood is collected from the emoral artery and fed to the myocardium with the aid of a ump that adjusts the pressure level and flow rate synchronized ith the diastolic phase. It has been reported that in OPCAB urgery with CAPS, there were no fatal arrhythmias or hemoynamic deterioration during anastomoses.1 A case of elective OPCAB surgery in which complete atrioventricular block and hypotension occurred before anastomoses in which CAPS was effective is presented.

Fractional Flow Reserve and Myocardial Perfusion Imaging in Patients With Angiographic Multivessel Coronary Artery Disease

The aim of this study was to investigate the correlation between myocardial ischemia detected by myocardial perfusion imaging (MPI) with single-photon emission computed tomography with intracoronary pressure-derived fractional flow reserve (FFR) in patients with multivessel coronary disease at angiography. Myocardial perfusion imaging can underestimate the number of ischemic territories in patients with multivessel disease. However, there are limited data comparing MPI and FFR, a highly accurate functional index of myocardial ischemia, in multivessel coronary disease. Sixty-seven patients (201 vascular territories) with angiographic 2- or 3-vessel coronary disease were prospectively scheduled to undergo within 2 weeks MPI (rest/stress adenosine) and FFR in each vessel. In 42% of patients, MPI and FFR detected identical ischemic territories (mean number of territories 0.9 +/- 0.8 for both; p = 1.00). In the remaining 36% MPI underestimated (mean number of territories; MPI: 0.46 +/- 0.6, FFR: 2.0 +/- 0.6; p < 0.001) and in 22% overestimated (mean number of territories; MPI: 1.9 +/- 0.8, FFR: 0.5 +/- 0.8; p < 0.001) the number of ischemic territories in comparison with FFR. There was poor concordance between the ability of the 2 methods to detect myocardial ischemia on both a per-patient (kappa = 0.14 [95% confidence interval: -0.10 to 0.39]) and per-vessel (kappa = 0.28 [95% confidence interval: 0.15 to 0.42]) basis. Myocardial perfusion imaging with single-photon emission computed tomography has poor concordance with FFR and tends to underestimate or overestimate the functional importance of coronary stenosis seen at angiography in comparison with FFR in patients with multivessel disease. These findings might have important consequences in using MPI to determine the optimal revascularization strategy in patients with multivessel coronary disease.

Predicting Myocardial Functional Recovery After Acute Myocardial Infarction: Relationship Between Myocardial Strain and Coronary Flow Reserve

Background and ObjectivesThe purpose of this study was to evaluate the relationship between myocardial strain and coronary flow reserve (CFR) in the prediction of myocardial functional recovery after acute myocardial infarction (AMI).Subjects and MethodsConsecutive patients with anterior ST elevation AMI were analyzed. Left ventricular (LV) strain, determined by 2-dimensional speckle tracking imaging and CFR, determined by intracoronary flow measurement, were obtained on the same day, 3-5 days after primary percutaneous coronary intervention. A-strain was defined as the mean systolic longitudinal strain of 11 LV segments (out of 18) assumed to be supplied by the left anterior descending coronary artery (LAD). Functional recovery was defined as improved wall motion >1 grade seen in at least 2 contiguous dysfunctional segments by echocardiography at the 6-month follow-up.ResultsOf 20 patients, 8 patients had preserved CFR (>2.0) and 12 patients had impaired CFR (≤2.0). There were no differences between the 2 CFR groups in LV ejection fractions and wall motion score indices in the LAD territory. However, A-strain was greater in patients with preserved CFR than in patients with impaired CFR (-6.4±2.0% vs. -4.6±1.4%, p=0.03). A-strain and CFR correlated well with each other (r=-0.49, p=0.03). Ten of 20 patients showed functional recovery at 6 months. Of clinical and echocardiographic parameters, A-strain was the only predictor of recovery (odds ratio 2.02, 95% confidence interval=1.03-3.97, p=0.04). For predicting recovery, the sensitivity and specificity were 80.0% and 80.0%, respectively, for CFR (cutoff=1.60), and 60.0% and 90.0%, respectively, for A-strain (cutoff=-6.13%).ConclusionMyocardial strain correlates well with the extent of microvascular integrity and can be used as a noninvasive method for predicting recovery after AMI.

Role of fractional and coronary flow reserve in clinical decision making in intermediate coronary lesions

Adequate patient selection for percutaneous coronary intervention is of the greatest importance in order to minimize early and late complications. Therefore, objective evidence for myocardial ischemia is mandatory for the management of patients with coronary artery disease, in particular in multivessel disease and those with intermediate lesions (40–70% diameter stenosis on angiography). The use of sensor-equipped guidewires for the assessment of functional coronary lesion severity has become extensive in the cardiac catheterization laboratory. The hemodynamic indices derived from intracoronary pressure or flow measurements, fractional flow reserve and coronary flow reserve, show a high agreement with noninvasive stress testing. Furthermore, deferral of percutaneous coronary intervention for hemodynamically nonsignificant lesions is associated with a low major adverse cardiac event rate. However, since these indices are based on either intracoronary pressure or flow, they do not investigate the hemodynami...

Diastolic Dysfunction in Diabetic Patients Assessed With Doppler Echocardiography: Relationship With Coronary Atherosclerotic Burden and Microcirculatory Impairment

Diabetes mellitus (DM) is associated with the development of both impaired left ventricular diastolic function (LVDF) and pathological changes in the coronary macro- and microcirculation. The aim of this study was to investigate the relationship between these manifestations of diabetic heart disease. The severity of atherosclerosis in the left anterior descending coronary artery (LAD) was quantified using intravascular ultrasound (IVUS) in 13 patients with DM and ischemic heart disease. The coronary flow velocity reserve (CFVR), instantaneous hyperemic diastolic velocity pressure slope index (IHDVPS) and zero-flow pressure were derived from digital intracoronary pressure and flow velocity measurements. The relationships between indices of LVDF (i.e. E/A and E/e' ratios) and intracoronary measurements were assessed. The left ventricular ejection fraction was 66+/-7%, and the LVDF indices were: E/A=0.92+/-0.38 and E/e'=9.90+/-2.80. There was a direct proportional relationship (r=0.62; P=.02) between E/e' and coronary resistance (1.93+/-0.74 mmHg/s) and an inverse proportional relationship (r=-0.64; P=.02) between E/e' and IHDVPS (1.56+/-0.50 cm/s/mmHg). However, no significant relationship was found between either LVDF index and CFVR (2.43+/-0.56) or coronary zero-flow pressure (40.41+/-10.66 mmHg). The volume of atheroma in the proximal 20 mm of the LAD (179.34+/-57.48 .l, with an average plaque area of 8.39+/-2.20 mm2) was not related to either LVDF index. In patients with DM and coronary atherosclerosis, there appeared to be a relationship between LVDF impairment (assessed by the E/e' ratio) and structural changes in the microcirculation.

A new angiographic method to assess coronary flow reserve—Validation in humans

Coronary flow reserve (CFR) is defined as the ratio between coronary artery flow during maximal hyperemia and rest. It is considered as a marker for the integrity of the epicardial coronary circulation and the microcirculation. CFR measurement typically requires the introduction of a guide wire into a diseased coronary artery. We tested a new algorithm, which allows to estimate CFR by analysis of coronary angiograms without the need for direct intracoronary measurements. Twenty seven patients (10 female, mean age 64 +/- 11 years) underwent diagnostic cardiac catheterization for the evaluation of chest pain. A Doppler wire was introduced into the diseased coronary artery and CFR(doppler) was calculated by the flow velocity ratio between rest and maximal hyperemia, induced by intravenous administration of 140 microg of adenosine per kg bodyweight. This was compared to the angiographically determined CFR (CFR(angio)) under the same conditions (rest and induced maximal hyperemia) by densitometry. CFR(angio) was based on the creation of two time density curves representing the disappearance of contrast over time. CFR(angio) was the resulting ratio between the density values during hyperemia and rest. An excellent correlation was found between CFR(doppler) and CFR(angio): CFR(angio) = 1 x CFR(doppler) (r = 0.87; P < 0.0001). The average absolute difference between both indeces was 0.36 +/- 0.31. Measurement of CFR(angio) by densitometry is feasible and provides results, which are comparable to Doppler-derived intracoronary flow velocity measurements.

Assessment of Microcirculatory Remodeling With Intracoronary Flow Velocity and Pressure Measurements

Intracoronary physiology techniques have been validated extensively for the assessment of epicardial stenoses but not for the lone study of coronary microcirculation. We performed a comparison between 4 intracoronary physiological indices with the actual structural microcirculatory changes documented in transplanted hearts. In 17 cardiac allograft patients without coronary stenoses, ECG, intracoronary Doppler flow velocity, and aortic pressure were digitally recorded before and during maximal hyperemia with a dedicated system. Postprocessing of data yielded 4 indices of microcirculatory status: coronary flow velocity reserve (2.13+/-0.59), instantaneous hyperemic diastolic velocity pressure slope (2.33+/-1.25 cm x s x (-1)mm Hg(-1)), coronary resistance index (1.65+/-0.88 mm Hg x cm(-1) x s(-1)), and coronary resistance reserve (2.36+/-0.65). Quantitative morphometry was performed in endomyocardial biopsies during the same hospital intake; arteriolar obliteration (76.57+/-6.95%) and density (2.00+/-1.22 arterioles per 1 mm(2)) and capillary density (645+/-179 capillaries per 1 mm(2)) were measured. Univariate regression analysis between intracoronary measurements and histological findings revealed that instantaneous hyperemic diastolic velocity-pressure slope correlated with arteriolar obliteration (r=0.58, P=0.014) and capillary density (r=0.60, P=0.012). Statistical adjustment revealed an independent contribution of arteriolar obliteration (beta=0.61, P=0.0009) and capillary density (beta=-0.60, P=0.0008) to instantaneous hyperemic diastolic velocity-pressure slope values, resulting in an excellent predictive model (r=0.84, P=0.0002). Coronary resistance index correlated only with capillary density (r=0.70, P=0.019). Relative indices (coronary flow velocity reserve and coronary resistance reserve) did not correlate significantly with arteriolar obliteration, capillary density, or arteriolar density. Intracoronary indices derived from pressure and flow, particularly instantaneous hyperemic diastolic velocity-pressure slope, appear to be superior to coronary flow velocity reserve in detecting structural microcirculatory changes. Both arteriolar obliteration and capillary rarefaction seem to influence microcirculatory hemodynamics independently.

Evaluating Patients With Persistent Chest Pain and No Obstructive Coronary Artery Disease

To the Editor: Dr Phan and colleagues presented 2 interesting patients with chest pain and normal coronary angiograms, speculating that for one patient the symptoms were due to microvascular coronary dysfunction and, for the other, due to abnormal cardiac nociception. I do not believe they have justified their conclusion that both patients illustrate the value of coronary reactivity testing. Indeed, the details of their diagnostic investigations are a reminder of the old saw that a well person is one who has not been completely worked up. The first patient, with cardiac syndrome X, had already had a negative radionuclide perfusion stress test (usually positive in this syndrome) and 2 normal coronary angiograms before commencing the workup discussed by the authors, which included repeat coronary angiography and insertion of an intracoronary flow wire followed by intracoronary infusion of vasoactive agents. The authors dismissed the negative stress test as reflecting the insensitivity of that test, although lack of specificity of the coronary reactivity testing is equally plausible. They justified the risks of the invasive evaluation by pointing out that patients with microvascular coronary dysfunction have an increased risk for adverse events, although no treatment has been demonstrated to reduce that risk. The 1 article cited to support an improved prognosis with treatment refers to hypertensive patients with abnormal brachial artery flow-mediated vasodilatation; whether these findings would apply to a nonhypertensive patient with microvascular coronary dysfunction is unknown. The second patient, a woman diagnosed with abnormal cardiac nociception, had normal coronary reactivity testing but had severe chest pain during flow-wire manipulations and infusions, requiring 2 doses of 25 μg of fentanyl for relief. She was treated with “reassurance and low-dose imipramine . . . ” and “has not sought additional testing at 18-month follow-up.” There is no evidence that the testing led to more effective therapy for this patient. I believe it would be a mistake to conclude that the coronary reactivity testing described by Phan et al is anything more than a research tool. Although the authors provided interesting theoretical explanations for the chest pain in their 2 patients, the diagnostic studies resulted in empirical, not tailored, therapy with no proven benefits in terms of symptom relief or prognosis. They therefore have not justified the increased risk and expense of the procedure.

Myocardial microcirculatory dysfunction after prolonged ventricular fibrillation and resuscitation

The etiology of postresuscitation myocardial stunning is unknown but is thought to be related to either ischemia occurring during cardiac arrest and resuscitation efforts and/or reperfusion injury after restoration of circulation. A potential common pathway for postischemia/reperfusion end-organ dysfunction is microvascular injury. We hypothesized that myocardial microcirculatory function is markedly abnormal in the postresuscitation period. In vivo study of myocardial microvascular function. University animal laboratory. Five swine (25 +/- 2 kg). Measurements before and after cardiac arrest and resuscitation. Baseline data were not different among the five subjects. Left ventricular ejection fraction was significantly lower at all postresuscitation time periods (p < .05), reaching a nadir of 19% at 1 hr postresuscitation. Cardiac output declined following fibrillation and resuscitation and was significantly lower than baseline at 1 and 4 hrs postresuscitation (p < .05). Prearrest coronary flow reserve, a ratio of normal to maximal intracoronary flow velocity, was 3.4 ("normal" ratio is 2:4), but was below normal (<2) throughout the 4-hr post resuscitation period (p < .05). This in vivo study showed that normal myocardial microcirculatory function is quickly lost after prolonged ventricular fibrillation and resuscitation. As early as 30 min postresuscitation the myocardial microcirculatory function is less than 50% of its prearrest baseline level. This dysfunction persists for at least 4 hrs. During the postresuscitation period, both left ventricular ejection fraction and cardiac output decline from their prearrest levels. No cause and effect relationship was proven, but a parallel decline in left ventricular function and coronary flow reserve is evident.

Comprehensive Assessment of Coronary Artery Stenoses: Computed Tomography Coronary Angiography Versus Conventional Coronary Angiography and Correlation With Fractional Flow Reserve in Patients With Stable Angina

We sought to determine the diagnostic accuracy of noninvasive visual (computed tomography coronary angiography [CTCA]) and quantitative computed tomography coronary angiography (QCT) to predict the hemodynamic significance of a coronary stenosis, using intracoronary fractional flow reserve (FFR) as the reference standard. It has been demonstrated that CTCA provides excellent diagnostic sensitivity for identifying coronary stenoses, but may lack accurate delineation of the hemodynamic significance. We investigated 79 patients with stable angina pectoris who underwent both 64-slice or dual-source CTCA and FFR measurement of discrete coronary stenoses. CTCA and conventional coronary angiography (CCA), and QCT and quantitative coronary angiography (QCA), were performed to determine the severity of a stenosis that was compared with FFR measurements. A significant anatomical or functional stenosis was defined as >/=50% diameter stenosis or an FFR <0.75. Stented segments and bypass grafts were not included in the analysis. A total of 89 stenoses were evaluated of which 18% (16 of 89) had an FFR <0.75. The diagnostic accuracy of CTCA, QCT, CCA, and QCA to detect a hemodynamically significant coronary lesion was 49%, 71%, 61%, and 67%, respectively. Correlation between QCT and QCA with FFR measurement was weak (R values of -0.32 and -0.30, respectively). Correlation between QCT and QCA was significant, but only moderate (R = 0.53; p < 0.0001). The anatomical assessment of the hemodynamic significance of coronary stenoses determined by visual CTCA, CCA, or QCT or QCA does not correlate well with the functional assessment of FFR. Determining the hemodynamic significance of an angiographically intermediate stenosis remains relevant before referral for revascularization treatment.

Effects of left ventricular unloading by Impella recover LP2.5 on coronary hemodynamics

We studied the effects of LV unloading by the Impella on coronary hemodynamics by simultaneously measuring intracoronary pressure and flow and the derived parameters fractional flow reserve (FFR), coronary flow velocity reserve (CFVR), and coronary microvascular resistance (MR). Patients with compromised left ventricular (LV) function undergoing high-risk percutaneous coronary intervention (PCI) may benefit from LV unloading. Limited information is available on the effects of LV unloading on coronary hemodynamics. Eleven patients (mean LV ejection fraction of 35 +/- 11%) underwent PCI during LV support by the LV unloading device (Impella Recover LP2.5). Intracoronary measurements were performed in a nonstenotic coronary artery after the PCI, before and after adenosine-induced hyperemia at four different support levels (0-2.5 L/min). Aortic and coronary pressure increased with increasing support levels, whereas FFR remained unchanged. Baseline flow velocity remained unchanged, while hyperemic flow velocity and CFVR increased significantly with increasing support levels (61 +/- 24 to 72 +/- 27 cm/sec, P = 0.001 and 1.88 +/- 0.52 to 2.34 +/- 0.63, P < 0.001 respectively). The difference between baseline MR and hyperemic MR significantly increased with increasing support levels (1.28 +/- 1.32 to 1.89 +/- 1.43 mm Hg cm(-1) sec, P = 0.005). Unloading of the LV by the Impella increased aortic and intracoronary pressure, hyperemic flow velocity and CFVR, and decreased MR. The Impella-induced increase in coronary flow, probably results from both an increased perfusion pressure and a decreased LV volume-related intramyocardial resistance.

Regadenoson, a selective A2A adenosine receptor agonist, causes dose-dependent increases in coronary blood flow velocity in humans

Regadenoson is a selective A2A adenosine receptor agonist and vasodilator used to increase the heterogeneity of distribution of coronary blood flow during myocardial perfusion imaging. This study characterized the dose dependence of regadenoson-induced coronary hyperemia. An open-label, dose-escalation study of regadenoson (10-500 microg, rapid intravenous bolus) was performed in 34 subjects; in 4 additional subjects, the effect of aminophylline to reverse the response to regadenoson was determined. Intracoronary peak blood flow velocity in either the left anterior descending or left circumflex artery was measured by continuous Doppler signal recording, heart rate, central aortic blood pressure, and adverse effects were recorded. Regadenoson increased peak blood flow velocity by up to 3.4-fold in a dose-dependent manner. The mean duration of the increase in flow velocity of 2.5-fold or greater caused by 400 to 500 microg of regadenoson was 2.3 to 2.4 minutes. Regadenoson (400-500 microg) increased heart rate by up to 21 +/- 6 beats/min and decreased systolic blood pressure (-5 +/- 8 mm Hg to -24 +/- 16 mm Hg) and diastolic blood pressure (-8 +/- 4 mm Hg to -15 +/- 14 mm Hg). Aminophylline (100 mg) attenuated the increase in peak flow velocity but not tachycardia caused by 400 microg of regadenoson. The results of this study demonstrate the utility of regadenoson as a coronary vasodilator for myocardial perfusion imaging.

Coronary microvascular dysfunction after myocardial infarction: increased coronary zero flow pressure both in the infarcted and in the remote myocardium is mainly related to left ventricular filling pressure

Objective:To investigate the underlying mechanisms of a decreased coronary flow reserve after myocardial infarction (MI) by analysing the characteristics of the diastolic hyperaemic coronary pressure–flow relationship.Design:Prospective study.Setting:Tertiary care hospital.Patients:68 patients...

Importance of collateral circulation in coronary heart disease

Collateral arteries are a common but inconsistent finding in coronary heart disease (CHD). We endeavoured to review the methods for coronary artery collateral assessment, the predictors and clinical importance of collateral blood flow, and the potential for therapeutic augmentation of collateral anastomoses. While many methods have been used to assess collateral blood flow only a few have been formally validated. Collateral flow index, as determined by measurement of intra-coronary pressure or flow velocity, is the most robust measure of collateral flow. These techniques have led to important advances in our understanding of collateral artery function. Coronary collateral arteries may prevent myocardial ischaemia in healthy subjects and in patients with CHD. A functional collateral circulation may lead to reduced ischaemia, preservation of ventricular function, and an improved prognosis. Recent trials have demonstrated that vascular progenitor cell therapies may improve ventricular function following acute myocardial infarction, raising the possibility of effective biological treatments to improve myocardial blood flow and prognosis in CHD. Coronary collateral anastomoses represent a prognostically important adaptive response in patients with CHD. Therapeutic augmentation of collaterals with emerging biological therapies represents a desirable goal for treating CHD patients.

Relation between transcardiac gradient of VEGF and coronary flow response in humans

Background Angiogenic growth factors, produced in the myocardium and coronary vascular bed, increase myocardial blood flow. This study examined whether plasma levels of vascular endothelial growth factor (VEGF) in coronary circulation may be related to coronary blood flow responses. Methods Blood flow responses in the left anterior descending coronary artery to an intracoronary infusion of acetylcholine (ACh) were measured by an intracoronary flow wire technique in 46 consecutive control subjects with normal coronary angiograms and left ventriculograms. Circulating VEGF levels were measured by ELISA in plasma obtained from the aortic root (AO) and anterior interventricular vein (AIV). Results The transcardiac gradient of VEGF, calculated by the difference in VEGF concentrations between the AIV and AO, showed a positive correlation with the coronary blood flow increase in response to ACh independently of traditional coronary risk factors. In patients with cardiac syndrome X ( n = 17), defined as a positive exercise stress test with a normal coronary angiograms and left ventriculogram, the transcardiac VEGF gradient was significantly lower than in the risk factors-matched control subjects ( n = 21). Conclusions The transcardiac gradient of plasma VEGF was independently and positively correlated with the coronary blood flow increase in response to ACh. A reduced transcardiac VEGF gradient was present in cardiac syndrome X, a condition with a blunted coronary blood flow response.