Comparison of intracoronary Doppler guide wire and transesophageal echocardiography in measurement of flow velocity and coronary flow reserve in the left anterior descending coronary artery

Echocardiographic assessment of coronary microvascular dysfunction: Basic concepts, technical aspects, and clinical settings

Coronary flow reserve is the capacity of the coronary circulation to augment the blood flow in response an increase in myocardial metabolic demands and has a powerful prognostic significance in different clinical situations. It might assess with invasive and noninvasive technique. Transthoracic echocardiography Doppler is an emerging diagnostic technique, noninvasive, highly feasible, safe for patient and physician, without radiation, and able to detect macrovascular and microvascular anomalies in the coronary circulation. This review aims to describe the benefit and limits of echocardiographic assessment of coronary flow reserve.

Effect of Erythropoietin Administration on Myocardial Viability and Coronary Microvascular Dysfunction in Anterior Acute Myocardial Infarction: Randomized Controlled Trial in the Japanese Population

Introduction

Cardioprotective effects of erythropoietin (EPO) on infarcted myocardium in acute myocardial infarction (AMI) patients have been inconclusive. This study aimed to assess the effect of EPO administration on coronary microvascular dysfunction (CMD) and myocardial viability in anterior AMI. We also evaluated the serial changes in CMD and cardiac remodeling in these patients.

Methods

Patients with a successful percutaneous coronary intervention (PCI) for the first anterior AMI were randomly assigned to two groups (EPO and control groups), and given single-dose intravenous administration of recombinant human EPO (12,000 IU) or saline after PCI. Delayed-enhanced cardiac magnetic resonance imaging was performed at 1 week after AMI to assess the average of transmural extent of infarction and infarct size. Coronary flow velocity reserve (CFVR) of the left anterior descending coronary artery was measured by Doppler echocardiography at 1 week, 1 month, and 8 months after AMI. All patients underwent clinical follow-up for the assessment of cardiac remodeling.

Results

Sixty-one patients (EPO 32, control 29) were eligible for analysis. EPO group (2.4 ± 1.2) had a tendency of smaller transmural extent of infarction than that of control group (2.9 ± 1.1; p = 0.063). CFVR-8 months improved significantly in EPO group (2.9 ± 0.6) compared to control group (2.6 ± 0.5; p = 0.04). Left atrial (LA) volume − 8 months was significantly lower in EPO group (47 ± 11) than those of control group (65 ± 20; p = 0.004).

Conclusions

A single medium dose of EPO could have a favorable effect on CMD and LA remodeling in the chronic phase of anterior AMI.

Trial Registration

The institutional ethics committee of Wakayama Medical University, identifier, 1125.

Electronic supplementary material

The online version of this article (10.1007/s40119-018-0122-1) contains supplementary material, which is available to authorized users.

A multi-scale model of the coronary circulation applied to investigate transmural myocardial flow

Distribution of blood flow in myocardium is a key determinant of the localization and severity of myocardial ischemia under impaired coronary perfusion conditions. Previous studies have extensively demonstrated the transmural difference of ischemic vulnerability. However, it remains incompletely understood how transmural myocardial flow is regulated under in vivo conditions. In the present study, a computational model of the coronary circulation was developed to quantitatively evaluate the sensitivity of transmural flow distribution to various cardiovascular and hemodynamic factors. The model was further incorporated with the flow autoregulatory mechanism to simulate the regulation of myocardial flow in the presence of coronary artery stenosis. Numerical tests demonstrated that heart rate (HR), intramyocardial tissue pressure (P_im ), and coronary perfusion pressure (P_per ) were the major determinant factors for transmural flow distribution (evaluated by the subendocardial-to-subepicardial (endo/epi) flow ratio) and that the flow autoregulatory mechanism played an important compensatory role in preserving subendocardial perfusion against reduced P_per . Further analysis for HR variation-induced hemodynamic changes revealed that the rise in endo/epi flow ratio accompanying HR decrease was attributable not only to the prolongation of cardiac diastole relative to systole, but more predominantly to the fall in P_im . Moreover, it was found that P_im and P_per interfered with each other with respect to their influence on transmural flow distribution. These results demonstrate the interactive effects of various cardiovascular and hemodynamic factors on transmural myocardial flow, highlighting the importance of taking into account patient-specific conditions in the explanation of clinical observations.

Coronary blood flow in patients with severe aortic stenosis before and after transcatheter aortic valve implantation

Patients with severe aortic stenosis and no obstructed coronary arteries are reported to have reduced coronary flow. Doppler evaluation of proximal coronary flow is feasible using transesophageal echocardiography. The present study aimed to assess the change in coronary flow in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). The left main coronary artery was visualized using transesophageal echocardiography in 90 patients undergoing TAVI using the Edwards SAPIEN valve. The peak systolic and diastolic velocities of the coronary flow and the time-velocity integral were obtained before and after TAVI using pulse-wave Doppler. Mean aortic gradients decreased from 47.1 ± 15.7 mm Hg before TAVI to 3.6 ± 2.6 mm Hg after TAVI (p <0.001). The aortic valve area increased from 0.58 ± 0.17 to 1.99 ± 0.35 cm(2) (p <0.001). The cardiac output increased from 3.4 ± 1.1 to 3.8 ± 1.0 L/min (p <0.001). Left ventricular end-diastolic pressure (LVEDP) decreased from 19.8 ± 5.4 to 17.3 ± 4.1 mm Hg (p <0.001). The following coronary flow parameters increased significantly after TAVI: peak systolic velocity 24.2 ± 9.3 to 30.5 ± 14.9 cm/s (p <0.001), peak diastolic velocity 49.8 ± 16.9 to 53.7 ± 22.3 cm/s (p = 0.04), total velocity-time integral 26.7 ± 10.5 to 29.7 ± 14.1 cm (p = 0.002), and systolic velocity-time integral 6.1 ± 3.7 to 7.7 ± 5.0 cm (p = 0.001). Diastolic time-velocity integral increased from 20.6 ± 8.7 to 22.0 ± 10.1 cm (p = 0.04). Total velocity-time integral increased >10% in 43 patients (47.2%). Pearson's correlation coefficient revealed the change in LVEDP as the best correlate of change in coronary flow (R = -0.41, p = 0.003). In conclusion, TAVI resulted in a significant increase in coronary flow. The change in coronary flow was associated mostly with a decrease in LVEDP.

Womersley number-based estimation of flow rate with Doppler ultrasound: sensitivity analysis and first clinical application

In this paper we continue in investigating the approach we have proposed in a paper recently published, for a reliable estimate of (peak systolic) blood flow rate from velocity Doppler measurements. Basic features of this approach together with some in silico test cases were discussed in that work. Here, we provide more insights of this approach by performing a sensitivity analysis of the formulas relating blood flow rate to velocity. In particular we analyze how our estimates are affected by perturbation or errors in measurements in comparison with a standard method for catheter based estimates based on the assumption of a parabolic velocity profile. A first glance to in vivo clinical applications is given as well.

Effects of percutaneous aortic valve replacement on coronary blood flow assessed with transesophageal Doppler echocardiography in patients with severe aortic stenosis

The aim of this study was to assess the change in coronary flow in patients who underwent percutaneous aortic valve replacement (PAVR) for severe aortic stenosis. The left main coronary artery was visualized using transesophageal echocardiography in 17 patients who underwent PAVR. The peak systolic and diastolic velocities of coronary flow and the time-velocity integral were obtained before and after PAVR using pulsed-wave Doppler. The median age was 80.0 years (interquartile range [IQR] 80.0 to 88.0). Median gradients decreased from 40.0 mm Hg (IQR 35.0 to 50.0) before PAVR to 4.0 mm Hg (IQR 2.75 to 4.2) afterward (p <0.001). Aortic valve area increased from 0.6 cm(2) (IQR 0.5 to 0.7) to 1.9 cm(2) (IQR 1.7 to 2.0) (p <0.001). Cardiac output increased from 3.3 L/min (IQR 2.4 to 4.0) to 3.6 L/min (IQR 3.1 to 4.4) (p <0.001). Aortic systolic pressure did not change significantly, from 126.0 mm Hg (IQR 11.7 to 137.7) before to 134 mm Hg (IQR 116.3 to 142.5) after valve implantation (p = 0.8). Left ventricular end-diastolic pressure decreased significantly from 19.0 mm Hg (IQR 18.0 to 22.0) before to 14.0 mm Hg (IQR 12.0 to 17.0) after valve implantation (p = 0.01). The medians of the following coronary flow parameters increased significantly after PAVR: peak systolic velocity, 25.0 cm/s (IQR 17.0 to 30.0) to 37.0 cm/s (IQR 23.0 to 44.0) (p <0.001); peak diastolic velocity, 49.0 cm/s (IQR 39.5 to 61.0) to 57.0 cm/s (IQR 42.9 to 83.9) (p = 0.006); total velocity-time integral, 23.7 cm (IQR 15.0 to 27.1) to 28.1 cm (IQR 21.3 to 34.7) (p = 0.001); and systolic velocity-time integral, 5.4 cm (IQR 3.5 to 6.2) to 9.0 cm (IQR 4.5 to 9.8) (p = 0.001). The diastolic time-velocity integral increased from 17.2 cm (IQR 12.0 to 24.0) to 20.1 cm (IQR 15.0 to 25.9) (p = 0.02). In conclusion, after PAVR, there is a significant increase in coronary flow as measured by peak systolic velocity, diastolic velocity, and velocity-time integral using pulsed-wave Doppler by transesophageal echocardiography.

The coronary flow velocity reserve measured by stress transoesophageal echocardiography evaluates the success of coronary interventions – Results of a 5-year follow-up

OBJECTIVES

The aim of the present study was to examine the long-term prognostic value of coronary flow velocity reserve (CFR) evaluated by means of stress transoesophageal echocardiography (STEE) in patients who have undergone percutaneous coronary intervention (PCI).

DESIGN

The study comprised 31 patients with significant LAD stenosis who underwent LAD-PCI. In consequence of their clinical signs, 11 subjects required rePCI or coronary artery bypass graft (CABG) operation within six months. The clinical status of the remaining 20 cases improved during the follow-up. STEE examinations were performed before LAD-PCI and after it.

RESULTS

The CFR of patients in a stable clinical condition improved during the follow-up, while the CFR of those who required rePCI or CABG remained unchanged. From this patient population, two subjects died during the 5-year follow-up.

CONCLUSIONS

Most of the patients who displayed an improved CFR after PCI suffered no major clinical events during the 5-year follow-up; in contrast, in those who a priori had a low CFR and did not show any improvement after PCI, major events did occur during this period.

Reduced aortic distensibility and coronary flow velocity reserve in diabetes mellitus patients with a negative coronary angiogram

BACKGROUND

Structural and functional abnormalities of the aortic wall and disturbances of the coronary circulation with presumed microvascular complications have been reported in patients with diabetes mellitus.

OBJECTIVES

To simultaneously establish the coronary flow velocity reserve (CFVR) and aortic distensibility indexes in type 2 diabetes mellitus patients who have normal epicardial coronary arteries by stress transesophageal echocardiography (STEE).

METHODS

The elastic properties of the descending aorta and the CFVR were evaluated simultaneously in 18 type 2 diabetes mellitus patients who had negative coronary angiograms. These results were compared with those of 21 nondiabetic subjects with normal epicardial coronary arteries and 24 patients with left anterior descending coronary artery (LAD) stenosis. STEE was used for the evaluation of elastic moduli of the descending aorta. The CFVR was calculated as the ratio of the average peak diastolic flow velocity during hyperemia to that at rest.

RESULTS

The CFVR of diabetic patients with normal epicardial coronary arteries and those with LAD stenosis was similarly decreased compared with the controls (2.10+/-0.63 and 1.78+/-0.47 versus 2.76+/-1.25, P<0.05 and P<0.001, respectively). The elastic modulus (in 103 mmHg) was similarly increased in patients with diabetes mellitus and normal epicardial coronary arteries, and in those with LAD stenosis, compared with the control subjects (0.94+/-0.82 and 0.91+/-0.59 versus 0.49+/-0.19, P<0.05 and P<0.05, respectively).

CONCLUSIONS

It may be stated that reduced aortic distensibility (increased elastic modulus) and the CFVR were demonstrated simultaneously during STEE in diabetic patients compared with nondiabetic subjects with negative coronary angiograms.

Is the coronary flow velocity reserve improvement after aortic valve replacement for aortic stenosis transient? Results of a 3-year follow-up

The coronary flow velocity reserve (CFR) is decreased in patients with aortic valve stenosis (AS). The aim of the present prospective study was to examine the CFR in AS patients with normal epicardial coronary arteries during a 3-year follow-up of aortic valve replacement (AVR). A total of 30 AS patients (17 women and 13 men) were enrolled in this prospective follow-up study; they all had a normal coronary angiogram and underwent dipyridamole stress transesophageal echocardiography (STEE) for CFR measurement before AVR. Nine of them participated in this 3-year follow-up study, and all patients were examined 16 months and 3 years after AVR by STEE. The CFR of AS patients was decreased before AVR. Different extents of diastolic coronary flow velocity reduction (resting and posthyperaemic) were observed resulting in a significant CFR improvement, despite the low number of patients during the 16-month follow-up. A further posthyperaemic flow velocity reduction was demonstrated after the 3-year follow-up, resulting in a significant CFR impairment. The CFR decreased in 5 cases, but remained practically unchanged in 3 after the first CFR measurement; only the CFR of 1 patient improved minimally. The main finding of the current study is that the CFR improvement 16 months after AVR, which paralleled the regression of the left ventricular hypertrophy, was found to be transient. Coronary flow velocity reserve impairment was demonstrated after the long-term (3-year) follow-up in most of the patients, which could not be explained by extravascular compressive forces.

Coronary and peripheral blood flow changes following biventricular pacing and their relation to heart failure improvement

AIMS

To study the effect of cardiac resynchronization therapy (CRT) on coronary and peripheral arterial circulation and to assess whether their changes are related to the improvement in patients' functional capacity and prognostically important biochemical markers.

METHODS AND RESULTS

Twenty-five patients were studied (New York Heart Association classes III and IV, left ventricular ejection fraction <35%, QRS>120 ms, mean age 66 +/- 2.1 years). Coronary blood flow (CBF), forearm blood flow (FBF), and their reserve were measured by transoesophageal echocardiography (in cm/s) and venous occlusion plethysmography (in mL/100 mL/min) at baseline and following 3 months of CRT. N-terminal-pro-brain natriuretic peptide (Nt-pro-BNP) and serum adhesion molecules, sICAM-1 and sVCAM-1 levels were also assessed. CRT induced a non-significant increase in resting CBF (baseline vs. CRT: 52.1 +/- 5.5 vs. 58.2 +/- 3.6, P: NS), whereas hyperaemic CBF was increased by CRT (baseline vs. CRT: 67.8 +/- 6.8 vs. 79.8 +/- 6.2, P < 0.05). Significant increases were observed in resting FBF (baseline vs. CRT: 1.6 +/- 0.2 vs. 2.6 +/- 0.2, P < 0.05) and hyperaemic FBF (baseline vs. CRT: 2.1 +/- 0.2 vs. 3.2 +/- 0.3, P < 0.05). The per cent difference in hyperaemic FBF was related to the per cent change in Nt-pro-BNP (r = -0.71, P < 0.05) and the per cent improvement in exercise duration (r = 0.80, P < 0.05).

CONCLUSION

CRT induces favourable changes in coronary and peripheral arterial function. Changes in peripheral blood flow are related to patients' improvement and may be prognostically significant.

Relation between Duke treadmill score and coronary flow reserve using transesophageal Doppler echocardiography in patients with microvascular angina

OBJECTIVES

The link between coronary flow reserve (CFR) and Duke treadmill score (DTS) in patients with microvascular angina remains elusive.

METHODS

We studied 108 subjects (M/F=48:60, mean age 54+/-9 years) with chest pain and normal coronary angiogram. ETT was performed by Bruce's protocol and the equation for calculating DTS was DTS=exercise duration-(5x ST deviation)-(4x exercise angina), with 0=none, 1=nonlimiting, 2=exercise limiting. The coronary flow velocity at diastole (PDV) using transesophageal Doppler echocardiography (TEE) was obtained from the proximal left anterior descending coronary artery and CFR was calculated as the ratio of hyperemic PDV after the intravenous infusion of dipyridamole (0.56 mg/kg) to baseline PDV.

RESULTS

CFR was 3.04+/-0.45 in group with negative ETT and 2.19+/-0.62 in group with positive ETT (P<0.001) and was 1.51+/-0.31 in high risk group with a score of < or = -11, 2.39+/-0.63 in moderate risk group with scores between -11 and + 5, and 3.04+/-0.43 in low risk group with a score of > or = +5 on DTS (P<0.001 versus low risk group, respectively). DTS has significant correlation with CFR (r=0.704, P<0.001).

CONCLUSIONS

DTS is a composite index that reflects CFR and helps clinicians determine the severity of ischemia in patients with microvascular angina.

Survey of observer variation in transesophageal echocardiography: comparison of anesthesiology and cardiology literature

OBJECTIVE

Transesophageal echocardiographic examination tends to be somewhat observer and experience dependent, and observer bias can arise easily when data are calculated and interpreted by unskilled, nonblinded, or single observers. The study plan was to see whether authors have adequately described how observer bias is minimized in their studies. Thus, a study was conducted systematically reviewing methods reported in transesophageal echocardio graphy articles in peer-reviewed anesthesiology journals versus those reported in peer-reviewed cardiology journals.

INTERVENTIONS

After MEDLINE searches of the literature published from 1997 through 1999, the authors investigated 56 anesthesiology reports and 56 randomly selected, year-matched cardiology reports. An 8-item questionnaire was developed that examined several factors: the number of observers and their experience levels, whether observers were blind to clinical data, whether low-quality images were excluded, the use of on-line or off-line analysis, and observer variability.

MAIN RESULTS

The analysis revealed inadequacies in reporting of important information that relates to bias and quality in 91.1% of anesthesiology and 98.2% of cardiology articles. Observer variability was not reported in 50.0% of the anesthesiology reports and 67.9% of the cardiology reports; however, difference between the 2 bodies of literature was not significant. The journal impact factor was significantly higher for the cardiology literature than for the anesthesiology literature (2.42 [0.386-10.893] v 1.07 [0.664-3.439]; median [range], p < 0.001).

CONCLUSION

Articles reviewed had at least some inadequacies in reporting the methods to minimize observer bias in both the anesthesiology and cardiology literature. Reporting methodology standards in TEE examinations remain to be established.

Coronary flow: clinical considerations

In the measurement of coronary blood flow to determine the success of percutaneous coronary intervention, invasive techniques, coupled with plaque characterisation and other intracoronary imaging modalities, may prove invaluable.

Lowering of blood pressure and coronary blood flow in isolated systolic hypertension

BACKGROUND

In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated systolic hypertension, a pathologic condition in which the elevated systolic blood pressure is associated with a lower than normal vascular compliance and normal or slightly greater than normal mean arterial pressure and vascular resistance.

OBJECTIVE

To evaluate the effects of rapid normalization of blood pressure on coronary blood flow in isolated systolic hypertension.

METHODS

We subjected 20 patients with isolated systolic hypertension to intraoperative hemodynamic and transesophageal echocardiographic monitoring during peripheral vascular surgery. Coronary flow velocity integrals and diameters in the left anterior descending coronary artery were evaluated under baseline conditions and after normalization of blood pressure, which occurred spontaneously during anesthesia (10 cases; group 1A) or was induced by infusion of nitrate (10 cases, group 1B).

RESULTS

After normalization of systolic blood pressure integrals decreased significantly only for patients in group 1A; percentage changes of diameter were significantly greater for patients in group 1B. Therefore, coronary blood flow after normalization of systolic blood pressure increased for patients in group 1B (by 28+/-25%) and decreased for patients in group 1A (by 30+/-21%). Changes in integrals were inversely related to those in diameter (r= -0.72, P < 0.001); for patients in group 1A changes in coronary perfusion pressure and diameter were related to those of integrals (r= 0.94; P < 0.0005).

CONCLUSIONS

In isolated systolic hypertension, despite there being similar changes of the systolic blood pressure, administration of nitrates caused a marked increase of coronary flow through direct effects on coronary circulation, whereas spontaneous normotension was associated with a significant reduction of coronary flow.

Transesophageal echocardiography (TEE) in the evaluation of the coronary arteries

With technical advancements, including high frequency, multiplane transducers, digital acquisition and display, and left-sided contrast agents, TEE is emerging as a promising method for evaluating coronary artery disease. Visualization of proximal coronary artery stenoses and coronary artery anomalies is already possible. Research studies using TEE measurement have contributed to understanding coronary artery physiology and may prove to be a valuable clinical tool in the future.

Echocardiographic assessment of coronary blood flow velocity during controlled hypotensive anesthesia with nitroglycerin

OBJECTIVE

To determine the effect of nitroglycerin on coronary blood flow velocity during controlled hypotensive anesthesia in humans.

DESIGN

Internally controlled prospective study.

SETTING

Single university hospital.

PARTICIPANTS

Twenty American Society of Anesthesiologists class I and II patients undergoing general anesthesia for surgical resection of a malignancy.

INTERVENTIONS

General anesthesia was induced with thiopental, fentanyl, and succinylcholine and maintained with isoflurane and vecuronium. Transesophageal echocardiography was used to evaluate left ventricular wall motion and blood flow velocity in the left anterior descending coronary artery. Intravenous nitroglycerin was used to reduce systolic arterial pressure to 60 to 70 mmHg. Intravenous albumin 5% was administered to maintain pulmonary capillary wedge pressure >5 mmHg.

MEASUREMENTS AND MAIN RESULTS

The left anterior descending coronary artery was visualized clearly in 16 of 20 patients. At a mean nitroglycerin dose of 16+/-14 microg/kg/min, peak diastolic left anterior descending flow velocity increased significantly from 32.5+/-10.3 cm/sec to 44.7+/-14.6 cm/sec (p = 0.0103). None of the patients developed any ST-segment changes.

CONCLUSIONS

During nitroglycerin-induced hypotensive anesthesia, coronary blood flow as assessed by peak diastolic left anterior descending flow velocity is preserved or increased in most patients. Increases in left anterior descending flow velocity are predictably achieved only at nitroglycerin doses >5 microg/kg/min. Intraoperative transesophageal echocardiography is useful in monitoring coronary flow velocity responses to controlled hypotensive anesthesia.

Usefulness of the response of flow velocity in the left anterior descending coronary artery to the cold pressor test for evaluating endothelium-dependent vascular relaxation in the coronary microvasculature by transesophageal echocardiography in subjects with angiographically normal coronary arteries

Measurement of flow velocity in the left anterior descending coronary artery by transesophageal echocardiography in subjects without risk factors for coronary artery disease (group 1) and in subjects with normal coronary arteries but conditions associated with endothelial dysfunction (group 2) revealed that there was a significantly impaired coronary flow velocity response to the cold pressor test in group 2 subjects. Thus, transesophageal echocardiography provides a minimally invasive tool for the functional assessment of endothelium and can be valuable in evaluating endothelial dysfunction and recovery in a variety of disease states.

Noninvasive Measurement of Left Coronary Blood Flow Reserve by Transthoracic Doppler Echocardiography: Comparison with Doppler Guidewire Ultrasonography

The development of new ultrasound instrumentation has made epicardial coronary artery blood flow imaging easier with the use of transthoracic coronary Doppler echocardiography (TCDE). This study was performed to investigate the accuracy of coronary blood flow reserve (CFR) measurement by TCDE. In 15 patients with ischemic heart disease in the absence of valvular disease or atrial fibrillation, coronary flow at rest and flow with hyperemia induced by intravenous dipyridamole infusion were recorded by TCDE and Doppler guidewire ultrasonography. The CFR was determined as the ratio of the maximum hyperemic diastolic time-averaged peak velocity to the velocity at rest in the proximal or distal left anterior descending coronary artery. It was found that the CFR of the left anterior descending coronary artery measured by TCDE was comparable in accuracy with CFR measured by invasive methods (r = 0.87, P < 0.0001, n = 15).

Estimation of coronary flow reserve using the Thrombolysis In Myocardial Infarction (TIMI) frame count method

A simple and readily available method of estimating coronary flow velocity reserve may have significant clinical value. With use of intracoronary adenosine we documented a very good correlation between coronary flow reserve values obtained with the Thrombolysis In Myocardial Infarction trial frame count method and the invasive Doppler wire (Flowire) technique.

Renal circulatory effects of adenosine in patients with chronic heart failure

OBJECTIVES

We sought to study the renal circulatory effects of adenosine in patients with chronic congestive heart failure (CHF).

BACKGROUND

Renal blood flow (RBF) is often reduced in patients with chronic CHF and may lead to decreased renal function. The cause of reduced RBF is multifactorial and involves systemic as well as local vasoregulatory mechanisms. Stimulation of renal adenosine A1 receptors in animal models has resulted in a significant vasoconstriction of afferent and efferent glomerular arterioles and deterioration of renal function. Although adenosine serum levels have been shown to be elevated in patients with CHF, their effect on the renal circulation in this patient population has not been studied.

METHODS

Nine patients with CHF from left ventricular systolic dysfunction were studied. The effects of adenosine at a dose of 10(-5) mol/liter infused directly into the main renal artery on heart rate, renal artery blood pressure, renal artery cross-sectional area (measured by intravascular ultrasound), renal Doppler blood flow velocity (measured by a Doppler flow wire in the renal artery), RBF and renal vascular resistance (RVR) were evaluated.

RESULTS

Infusion of adenosine resulted in no significant effect on heart rate or renal artery blood pressure but caused a substantial increase in RVR (11,204 +/- 1,469 to 31,494 +/- 3,911 dynes x s x cm(-5), p = 0.0005), which led to a marked fall in RBF in every patient (mean values 376 +/- 36 to 146 +/- 22 ml/m2, p = 0.0002). These changes in RVR and RBF were associated with no significant change in renal artery cross-sectional area (0.389 +/- 0.040 to 0.375 +/- 0.033 cm2, p = 0.3).

CONCLUSIONS

Stimulation of renal adenosine receptors in patients with CHF results in marked renal vasoconstriction that leads to an important reduction in RBF. Lack of change in renal artery cross-sectional area suggests that adenosine affects intrarenal resistance blood vessels rather than large conductance vessels. These results may indicate a rationale for investigation of renal adenosine receptor blockade for enhancement of RBF and improvement of renal function in patients with chronic CHF.