Brachial Artery Flow Velocity Research Articles

Arterial Pulsatility in Patients with Continuous Flow Left Ventricular Assist Device Support: Comparing Velocity and Mean Arterial Pressure

<h3>Purpose</h3> An increasing number of end-stage heart failure patients are supported by continuous-flow Left Ventricular Assist Devices (cfLVADs) as a bridge to heart transplantation. Accurate assessment of arterial pulsatility remains a challenge because of diminished pulse pressure, which itself can be associated with adverse events such as gastrointestinal bleeding and stroke. Our study investigates the value of simultaneous arterial pressure and arterial blood velocity assessment in cfLVAD patients. <h3>Methods</h3> Brachial artery flow velocity (cm/s, Huntleigh) and brachial cuff oscillometry pressure (mmHg, Sphygmocor XCel) data were collected during outpatient visit. Velocity measurements obtained included peak, minimum, average velocity as well as pulsatility index. Pressure measurements obtained were systolic, diastolic as well as mean arterial pressure. <h3>Results</h3> Twelve velocity and pressure measurements were obtained from a total of nine VAD patients. Mean age was 57 years (Range 44-71). Mean device support duration was 187 days (Range 44-471). Mean brachial MAP was 92 mmHg (Range 74-112), whereas mean peak brachial artery velocity was 11 cm/s (Range 6-26). Mean pulsatility index was 3 (range 1-8). Correlation analysis using Spearman's rho demonstrated a significant inverse relationship between Brachial MAP and Peak velocity (Rho=-0.72, p=0.08). <h3>Conclusion</h3> Arterial flow measurements may provide incremental value over purely pressure-based assessment. Discrepancies between these modalities may provide further information regarding the arterial vasculature, specifically pertaining to the impact of higher MAP on blood flow.

Acute hyperglycaemia enhances both vascular endothelial function and cardiac and skeletal muscle microvascular function in healthy humans.

Multiple clinical studies report that acute hyperglycaemia (induced by mixed meal or oral glucose) decreases arterial vascular function in healthy humans. Feeding, however, impacts autonomic output, blood pressure, and insulin and incretin secretion, which may themselves alter vascular function. No prior studies have examined the effect of acute hyperglycaemia on both macro- and microvascular function while controlling plasma insulin concentrations. Macrovascular and microvascular functional responses to euglycaemia and hyperglycaemia were compared. Octreotide was infused throughout both protocols to prevent endogenous insulin release. Acute hyperglycaemia (induced by intravenous glucose) enhanced brachial artery flow-mediated dilatation, increased skeletal muscle microvascular blood volume and flow, and expanded cardiac muscle microvascular blood volume. Compared to other published findings, the results suggest that vascular responses to acute hyperglycaemia differ based on the study population (i.e. normal weight vs. overweight/obese) and/or glucose delivery method (i.e. intravenous vs. oral glucose). High glucose concentrations acutely provoke endothelial cell oxidative stress and are suggested to trigger diabetes-related macro- and microvascular injury in humans. Multiple clinical studies report that acute hyperglycaemia (induced by mixed meal or oral glucose) decreases arterial vascular function in healthy humans. Feeding, however, impacts autonomic output, blood pressure, and insulin and incretin secretion, which may each independently alter vascular function and obscure the effect of acute hyperglycaemia per se. Surprisingly, no studies have examined the acute effects of intravenous glucose-induced hyperglycaemia on both macro- and microvascular function while controlling plasma insulin concentrations. In this randomized study of healthy young adults, we compared macrovascular (i.e. brachial artery flow-mediated dilatation, carotid-femoral pulse wave velocity and post-ischaemic brachial artery flow velocity) and microvascular (heart and skeletal muscle perfusion by contrast-enhanced ultrasound) functional responses to euglycaemia and hyperglycaemia. Octreotide was infused throughout both protocols to prevent endogenous insulin release. Acute intravenous glucose-induced hyperglycaemia enhanced brachial artery flow-mediated dilatation (P=0.004), increased skeletal muscle microvascular blood volume and flow (P=0.001), and expanded cardiac muscle microvascular blood volume (P=0.014). No measure of vascular function changed during octreotide-maintained euglycaemia. Our findings suggest that unlike meal-provoked acute hyperglycaemia, 4h of intravenous glucose-induced hyperglycaemia enhances brachial artery flow-mediated dilatation, provokes cardiac and skeletal muscle microvascular function, and does not impair aortic stiffness. Previous findings of acute large artery vascular dysfunction during oral glucose or mixed meal ingestion may be due to differences in study populations and meal-induced humoral or neural factors beyond hyperglycaemia per se. (ClinicalTrials.gov number NCT03520569.).

Endothelial and left ventricular diastolic function in young adults exposed to tobacco.

Smoking is associated with endothelial and left ventricular diastolic disfunction. We aimed to determine the endothelial and diastolic function in young adults exposed to tobacco smoke and the effects of acute exposure to it. Smokers were considered as cases and non-smokers as controls. Brachial artery diameter, brachial artery flow velocity, and echocardiographic variables were measured. Mean age of the participants was 21 years. Smokers showed significant endothelial dysfunction compared with non-smokers. Arterial dilation mediated by the endothelium was significantly higher in non-smokers than in smokers (p = 0.005). Non-endothelium-mediated arterial dilation was significantly impaired in smokers compared with non-smokers (p = 0.02). After reactive hyperaemia, there was a significant increase in blood flow in non-smokers (61%) compared with that in smokers (29%). Acute cigarette exposure showed a trend towards left ventricle diastolic disfunction in smokers. Left atrium diameter was significantly higher in smokers than in non-smokers. After acute exposure to cigarette smoke, arterial dilation and brachial flow velocity were lower than those achieved in the abstinence phase (p = 0.005). We concluded that endothelium-dependent arterial dilation is impaired in young smokers and it worsens even after acute exposure to cigarette smoke.

CO-28: Flow-mediated dilatation (FMD) and endothelium-independent dilation (EID) in patients with multifocal fibromuscular dysplasia: a cross-sectional study

Background Fibromuscular dysplasia (FD) is a rare idiopathic, segmental, non-atherosclerotic non-inflammatory vascular disease, which occurs mostly in middle-aged patients and affects medium-sized arteries (renal and carotid arteries). We previously showed that FD is a general arterial disease with focal exacerbation of the trait. However, whether endothelial dysfunction may be involved in the pathophysiology of FD is unclear. Abstract CO-28 – Table FD EH HS Age, yrs 52 ± 9 52 ± 9 52 ± 9 Women, n (%) 43 (86%) 43 (86%) 42 (84%) Caucasian, n (%) 38 (76%) 38 (76%) 42 (84%) Office SBP, mmHg 125 ± 15*** 121 ± 12*** 113 ± 10 Antihypertensive drugs, n (range) 2 (1-4) 2 (1-4) 0 BA structure External diameter, mm 3.91 ± 0.72° 4.19 ± 0.69 4.00 ± 0.64 Distensibility, μm 114 ± 64 115 ± 57 135 ± 73 IMT, μm 319 ± 79 330 ± 85 303 ± 97 Internal diameter, mm 3.34 ± 0.64 3.56 ± 0.66 3.47 ± 0.57 FMD Basal BA diameter; mm 3.86 ± 0.70*° 4.17 ± 0.63 4.02 ± 0.65 BA diameter (hand ischemia), mm 3.91 + 0.71°° 4.22 + 0.64 4.04 + 0.61 BA diameter (hand hyperhemia), mm 3.98 ± 0.73*° 4.29 ± 0.63 4.16 ± 0.62 Change in BA diameter, % 2.39 [0.31; 5.41] 2.85 [–0.23; 6.15] 2.67 [0.20; 5.73] Basal BA flow velocity, cm/s 7.70 ± 5.99 7.39 ± 5.98 7.66 ± 8.53 BA flow velocity (ischemia), cm/s 3.71 ± 5.25 2.68 ± 5.01 0.98 ± 2.54 BA flow velocity (hyperhemia) cm/s 73 ± 29 69 ± 27 78 ± 38 EID Basal BA diameter, mm 3.92 ± 0.69°° 4.22 ± 0.67 4.07 ± 0.67 Post-GTN BA diameter, mm 4.43±0.69**°° 4.82 ± 0.61 4.74 ± 0.71 Change in BA diameter, % 13.8 [7.9;19.0] 15.3 [10.2; 18.9] 18.4 [12.9;21.1] Post-GTN BA flow velocity, cm/s 7.27 ± 8.12 5.56 ± 6.84 4.76 ± 10.29 * P < 0.05, ** P < 0.01, *** P < 0.001 vs. HS Full-size table Table options View in workspace Download as CSV Methods In a cross sectional study, we compared the endothelial function between 50 patients with multifocal FD of renal/carotid arteries confirmed by CT-angiography, 50 essential hypertensive (EH) patients matched for age, sex, ethnicity and BP and 50 healthy subjects (HS) matched for age, sex and ethnicity. Exclusion criteria were: tobacco consumption, hypercholesterolemia, diabetes, aspirin or statin treatment. Brachial artery (BA) FMD after release of hand ischemia and glyceryl trinitrate (GTN)-induced EID were measured using a high-resolution radiofrequency – based echotracking system blind to the diagnosis. Results FD, EH and HS were well matched. FD and EH had significantly higher SBP than HS despite antihypertensive treatments. BA external diameter was significantly lower in FD than in both HS and EH before, during and after hand ischemia and after GTN. BA intima media thickness (IMT), internal diameter and distensibility did not differ between the 3 groups. The percent changes in BA diameter after release of hand ischemia (FMD) or GTN administration (EID) did not significantly differ between the 3 groups. BA flow velocity did not significantly differ in any experimental condition. Conclusions In conclusion, despite showing similar acute vasodilatory responses to flow and GTN, FD patients differed from EH and HS in terms arterial morphology with smaller BA diameter associated with similar IMT. The similarity of the IMT between the groups, combined with the reduction of the BA diameter in FD patients suggests that the BA underwent inward eutro-phic remodeling despite normal blood flow velocity. This paradoxical remodeling may suggest a chronic defect in the endothelium-dependent pathways involved in arterial remodeling in FD patients.

6D.03

Objective: Fibromuscular dysplasia (FD) is a rare idiopathic, segmental, non-atherosclerotic non-inflammatory vascular disease. We previously showed that FD is a general arterial disease with focal exacerbation of the trait. However, whether endothelial dysfunction may be involved in the pathophysiology of FD is unclear. Design and method: In a cross sectional study, we compared the endothelial function between 50 patients with multifocal FD of renal/carotid arteries confirmed by CT-angiography, 50 essential hypertensive (EH) patients matched for age, sex, ethnicity and BP and 50 healthy subjects (HS) matched for age, sex and ethnicity. Exclusion criteria were: tobacco consumption, hypercholesterolemia, diabetes, aspirin or statin treatment. Brachial artery (BA) FMD after release of hand ischemia and glyceryl trinitrate (GTN)-induced EID was measured using a high-resolution radiofrequency–based echotracking system blind to the diagnosis. Results: FD, EH and HS were well matched (52yrs, 85% women, 80% caucasian). SBP was higher in FD (125 ± 15mmHg) and EH (121 ± 12mmHg) than EH (113 ± 10mmHg) despite antihypertensive treatments. BA external diameter was significantly lower in FD than in both HS and EH before, during and after hand ischemia and after GTN. BA intima media thickness (IMT), internal diameter did not differ between the 3 groups. FMD (%) or EID (%) did not significantly differ between the 3 groups. BA flow velocity did not significantly differ in any experimental condition.Conclusions: In conclusion, despite showing similar acute vasodilatory responses to flow and GTN, FD patients differed from EH and HS in terms of arterial morphology with smaller BA diameter associated with similar IMT. This paradoxical remodeling may suggest a chronic defect in the endothelium-dependent pathways involved in arterial remodeling in FD patients.

Estimation of brachial artery volume flow by duplex ultrasound imaging predicts dialysis access maturation

This study validated duplex ultrasound measurement of brachial artery volume flow (VF) as predictor of dialysis access flow maturation and successful hemodialysis. Duplex ultrasound was used to image upper extremity dialysis access anatomy and estimate access VF within 1 to 2 weeks of the procedure. Correlation of brachial artery VF with dialysis access conduit VF was performed using a standardized duplex testing protocol in 75 patients. The hemodynamic data were used to develop brachial artery flow velocity criteria (peak systolic velocity and end-diastolic velocity) predictive of three VF categories: low (<600 mL/min), acceptable (600-800 mL/min), or high (>800 mL/min). Brachial artery VF was then measured in 148 patients after a primary (n = 86) or revised (n = 62) upper extremity dialysis access procedure, and the VF category correlated with access maturation or need for revision before hemodialysis usage. Access maturation was conferred when brachial artery VF was >600 mL/min and conduit imaging indicated successful cannulation based on anatomic criteria of conduit diameter >5 mm and skin depth <6 mm. Measurements of VF from the brachial artery and access conduit demonstrated a high degree of correlation (R(2) = 0.805) for autogenous vein (n = 45; R(2) = 0.87) and bridge graft (n = 30; R(2) = 0.78) dialysis accesses. Access VF of >800 mL/min was predicted when the brachial artery lumen diameter was >4.5 mm, peak systolic velocity was >150 cm/s, and the diastolic-to-systolic velocity ratio was >0.4. Brachial artery velocity spectra indicating VF <800 mL/min was associated (P < .0001) with failure of access maturation. Revision was required in 15 of 21 (71%) accesses with a VF of <600 mL/min, 4 of 40 accesses (10%) with aVF of 600 to 800 mL/min, and 2 of 87 accesses (2.3%) with an initial VF of >800 mL/min. Duplex testing to estimate brachial artery VF and assess the conduit for ease of cannulation can be performed in 5 minutes during the initial postoperative vascular clinic evaluation. Estimation of brachial artery VF using the duplex ultrasound, termed the "Fast, 5-min Dialysis Duplex Scan," facilitates patient evaluation after new or revised upper extremity dialysis access procedures. Brachial artery VF correlates with access VF measurements and has the advantage of being easier to perform and applicable for forearm and also arm dialysis access. When brachial artery velocity spectra criteria confirm a VF >800 mL/min, flow maturation and successful hemodialysis are predicted if anatomic criteria for conduit cannulation are also present.

Brachial artery flow velocity variation: another victory for hand-carried ultrasound?

Dynamic predictors are clearly superior to static pressures in predicting whether a patient will respond to a fluid bolus. Hand-carried ultrasound (HCUS) can measure changes in blood flow velocity in the brachial artery that parallel arterial pulse pressure variation. The potential for HCUS to guide fluid therapy non-invasively must overcome problems of sensitivity and applicability.

Flow-mediated dilatation of the brachial artery and left ventricular geometry in hypertensive patients.

In arterial hypertension, the spectrum of geometric patterns in the left ventricle may parallel the structural alterations detected in the carotid arteries and in subcutaneous small arteries. It has been also reported that hypertensive left ventricular hypertrophy (LVH) may be associated with endothelial dysfunction, as evaluated by the response of coronary or forearm vasculature to acetylcholine infusion. The aim of this study was to evaluate the flow-mediated vasodilatation (FMD) of the brachial artery, non-invasive estimate of endothelium-dependent vasodilatation according to left ventricular geometric adaptations in hypertensive patients. In 16 normotensive (nine males, seven females, aged 40-68 years) and in 78 hypertensive subjects (50 males, 28 females, aged 42-67 years), we performed an echocardiographic study for the measurement of left ventricular mass index (LVMI) and relative wall thickness (RWT); we measured to a high resolution the brachial artery diameter at rest, during reactive hyperaemia (5 min of brachial artery occlusion) and after sublingual glyceril trinitrate (GTN); brachial artery flow velocity was measured by pulsed Doppler. Twenty-six hypertensive patients had a normal LVMI (LVMI < 51 g/ m2.7) and geometry (RWT < 0.44), five had concentric remodelling (RWT > or = 0.44), and concentric and eccentric LVH were observed in 19 and 28 patients, respectively. FMD was reduced in hypertensive patients as compared with normotensive subjects (P< 0.01). No correlation was found between FMD and LVMI (r= -0.078) or RWT (r = 0.049); in addition, no difference in FMD was found among the left ventricular geometric patterns in hypertensive patients. In hypertensives, the presence of endothelial dysfunction is not associated with the LVH or with different left ventricular geometric patterns, suggesting that different and independent mechanisms may be responsible for the presence of LVH and of endothelial dysfunction.

Brachial artery blood flow velocity pattern in patients with congestive heart failure: duplex Doppler ultrasonographic assessment.

The purpose of this study was to determine whether there are abnormalities in blood flow velocity pattern of the brachial artery in patients with congestive heart failure (CHF). Brachial artery blood flow velocities were measured with duplex Doppler ultrasonography in 12 normal subjects, 31 patients with congestive heart failure (CHF), and 26 patients with coronary artery disease (CAD). None of the patients had clinical evidence of arterial disorders at upper extremities. In both patient groups, the presence of hypertension was correlated with the peak systolic velocity (r=0.48, p<0.05). Patients with heart failure had significantly larger (p<0.0001) peak reverse velocity (20 +/- 6 m/sec) than healthy subjects (5 +/- 4 m/sec) and patients with CAD (7 +/- 3 m/sec). Peak reverse velocity did not differ significantly between normal subjects and CAD group. These data indicate that the blood flow velocity pattern at brachial artery is abnormal in CHF. The simple measurement of brachial artery flow velocity suggests changes in peripheral vasculature related to CHF.

Brachial artery flow pattern and clinical backgrounds in patients with angina pectoris.

Blood flow velocity of the brachial artery was measured noninvasively by ultrasound pulsed Doppler technique under the guidance of a B-mode ultrasound image in 56 patients with angina pectoris. There was no significant stenosis along the brachial artery on a B-mode image. The authors investigated seven clinical backgrounds for each patient, ie, age, gender, absence or presence of smoking, hyperlipidemia, diabetes mellitus, hypertension, and the number of significantly stenosed (> or =50%) coronary arteries. Among these variables, the determinants of the brachial artery velocity profile were selected by stepwise multiple regression analysis. Selected variables were the presence of hypertension for peak systolic velocity (R=0.276), age and the number of diseased vessels for peak reverse velocity (R=0.624), and age for peak diastolic velocity (R=0.609). The peak systolic velocity was larger in patients with hypertension than in those without it (0.565+/-0.023 vs 0.490+/-0.013 m/see, P<0.05), and the peak reverse velocity was larger in patients with multivessel disease than those without it (-0.117+/-0.071 vs -0.053+/-0.081 m/sec, P<0.01). Thus, the level of flow velocity of the brachial artery in patients with angina pectoris was partly determined by age, hypertension, and severity of coronary artery disease. The simple measurement of brachial artery flow velocity suggests changes in peripheral vasculature related to atherosclerosis.

Does the brachial artery doppler flow velocity waveform reflect changes in downstream impedance?

Brachial artery Doppler flow velocity waveforms were recorded from 10 nonpregnant women and 19 women with uncomplicated pregnancies. The pregnant group showed higher peak systolic frequencies (3.24 compared with 2.26, p = 0.01), higher maximum end-diastolic frequencies (0.62 compared with 0.25, p = 0.01), and lower pulsatility indices (2.57 compared with 3.95, p = 0.06) when compared with the nonpregnant group. These Doppler changes could reflect the increase in maternal cardiac output and decline in systemic vascular resistance that occur in normal pregnancy. The effect on brachial artery Doppler of acutely increasing downstream impedance by hand immersion in ice-cold water was studied in nine women with uncomplicated pregnancies at 32 to 38 weeks' gestation. Immersion for 15 seconds was associated with a significant reduction in peak systolic frequencies (from 3.06 to 1.97, p ≤ 0.005) and maximum end-diastolic frequencies (from 0.82 to 0.03, p ≤ 0.005) and a significant increase in the pulsatility index (from 1.87 to 5.62, p ≤ 0.005). These changes persisted for the duration of immersion (60 seconds). After immersion, the brachial artery flow velocity waveform returned to its preimmersion pattern by 60 seconds. We conclude that in normal pregnancy, the maternal brachial artery Doppler flow velocity waveform reflects acute and chronic changes in downstream impedance. (AM J OBSTET GYNECOL 1991;165:1741-4.)

Telemetry of arterial flow in man with a Doppler ultrasonic flowmeter

1. 1. Transcutaneous measurements of brachial artery flow velocity with the Doppler ultrasonic flowmeter were made in 82 subjects, of whom 24 were normal and 58 had heart disease. 2. 2. Aortic stenosis was associated with low peak flow velocity, prolonged ascending limb of the primary wave and decreased retrograde wave. Aortic insufficiency was recognized by the presence of a large secondary wave thought to represent retrograde flow. Subaortic stenosis altered the flow waveform in a characteristic manner. 3. 3. The technic was also found to be useful in the study of cardiac arrhythmias, Valsalva maneuvers and in the study of drugs with primary effect on the peripheral circulation. 4. 4. Although more experience is needed with its use in man, it appears that it may become a useful technic for monitoring patients in intensive care units.