Measurement Of Coronary Flow Velocity Research Articles

Echocardiographic functional determinants of survival in heart failure with abnormal ejection fraction

Background and AimsPatients with heart failure (HF) with reduced left ventricular (LV) ejection fraction (EF) have a heterogeneous prognosis, and assessment of coronary physiology with coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) may complement established predictors based on wall motion and EF.Methods and resultsIn a prospective multicenter study design, we enrolled 1,408 HF patients (age 66 ± 12 years, 1,035 men), with EF <50%, 743 (53%) with coronary artery disease, and 665 (47%) with normal coronary arteries. Recruitment (years 2004–2022) involved 8 accredited laboratories, with inter-observer variability <10% for CFV measurement. Baseline CFV (abnormal value >31 cm/s) was obtained by pulsed-wave Doppler in mid-distal LAD. CFVR (abnormal value ≤2.0) was assessed with exercise (n = 99), dobutamine (n = 100), and vasodilator stress (dipyridamole in 1,149, adenosine in 60). Inducible myocardial ischemia was identified with wall motion score index (WMSI) stress > rest (cut-off Δ ≥ 0.12). LV contractile reserve (CR) was identified with WMSI stress < rest (cutoff Δ ≥ 0.25). Test response ranged from score 0 (EF > 30%, CFV ≥ 32 cm/s, CFVR > 2.0, LVCR present, ischemia absent) to score 5 (all steps abnormal). All-cause death was the only endpoint. Results. During a median follow-up of 990 days, 253 patients died. Independent predictors of death were EF (HR: 0.956, 95% CI: 0.943–0.968, p < 0.0001), CFV (HR: 2.407, 95% CI: 1.871–3.096, p < 0.001), CFVR (HR: 3.908, 95% CI: 2.903–5.260, p < 0.001), stress-induced ischemia (HR: 2.223, 95% CI: 1.642–3.009, p < 0.001), and LVCR (HR: 0.524, 95% CI: 0.324–.647, p = 0.008). The annual mortality rate was lowest (1.2%) in patients with a score of 0 (n = 61) and highest (31.9%) in patients with a score of 5 (n = 15, p < 0.001).ConclusionHigh resting CFV is associated with worse survival in ischemic and nonischemic HF with reduced EF. The value is independent and additive to resting EF, CFVR, LVCR, and inducible ischemia.

Anatomical, functional and prognostic correlates of resting coronary flow velocity in patients with hypertrophic cardiomyopathy

Abstract Background The clinical significance of baseline peak diastolic coronary flow velocity (CFV) in the left anterior descending coronary artery (LAD) has not been investigated yet in patients with hypertrophic cardiomyopathy (HCM). Aim To assess the anatomical, functional and prognostic correlates of baseline LAD CFV in HCM. Methods 384 consecutive adult HCM patients (age=52+15 years, 164 [43%] females) with no known coronary artery disease from 8 centers in 5 countries were prospectively analyzed. All patients underwent comprehensive transthoracic echocardiography including CFV measurement with pulse wave Doppler in the mid-distal LAD. All patients had preserved left ventricular (LV) function. LV force was calculated as (peak instantaneous LV outflow tract gradient+systolic blood pressure)/LV end-systolic volume. Patients were followed for a median of 50 months (IQ range 18-97 months), the outcome measure was a composite endpoint of all-cause death and acute heart failure. Results The mean CFV was 36±11 cm/s. CFV was positively correlated with LV maximal wall thickness (r=0.375, p<0.001), LV maximal septal thickness (r=0.320, p<0.001), resting LV outflow tract gradient (r=0.274, p<0.001), LV force (r=0.227, p<0.001), mean E/e’ (r=0.479, p<0.001) and heart rate (r=0.221, p<0.001). During follow-up, 54 events occurred (33 all-cause deaths and 21 acute heart failures). Receiver operating characteristic analysis was used to determine the best cut-off value of CFV (>31 cm/s) to predict the composite endpoint. Patients with CFV >31 cm/s had a significantly worse 10-year event-free survival compared to those with CFV ≤31 cm/s, see Figure. Conclusion Higher resting LAD CFV is associated with greater LV wall thickness, higher LV outflow tract gradient, faster heart rate and more elevated left ventricular filling pressures in HCM. Elevated resting CFV may indicate a coronary microcirculation dysfunction either primary or secondary to anatomical (septal hypertrophy), functional (increased myocardial oxygen demand), or autonomic (increased sympathetic drive) determinants. Whatever the underlying endotype, high resting CFV is related to worse prognosis in the long term.Figure.

Independent prognostic value of ejection fraction, resting coronary flow, coronary flow reserve, myocardial viability, and inducible ischemia in heart failure with a reduced ejection fraction

Abstract Background and Aims Patients with heart failure (HF) with reduced left ventricular (LV) ejection fraction (EF) have a heterogeneous prognosis, and assessment of coronary physiology with coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) may complement established predictors based on wall motion. Methods and results In a prospective multicenter study design, we enrolled 1,408 HF patients (age 66±12 years, 1,035 men), with EF <50%, 743 (53%) with coronary artery disease, and 665 (47%) with normal coronary arteries. Recruitment (years 2004-2022) involved 8 accredited laboratories, with inter-observer variability <10% for CFV measurement. Baseline CFV (abnormal value >31 cm/s) was obtained by pulsed-wave Doppler in mid-distal LAD. Coronary flow velocity reserve (CFVR, abnormal value ≤2.0) was assessed with exercise (n=99), dobutamine (n=100), and vasodilator stress (dipyridamole in 1,149, adenosine in 60). Inducible myocardial ischemia was identified with wall motion score index (WMSI) stress> rest (cut-off ∆≥0.12). LV contractile reserve (CR) was identified with WMSI stress< rest (cutoff ∆≥0.25). Test response ranged from score 0 (EF>30%, CFV ≤31 cm/s, CFVR >2.0, LVCR present, ischemia absent) to score 5 (all steps abnormal). All-cause death was the only end-point. Results During a median follow-up of 990 days, 253 patients died. Independent predictors of death were EF (HR: 0.956, 95% CI: 0.943-0.968, p<0.0001), CFV (HR: 2.407, 95% CI: 1.871-3.096, p<0.001), CFVR (HR: 3.908, 95% CI: 2.903-5.260, p<0.001), stress-induced ischemia (HR: 2.223, 95% CI: 1.642-3.009, p<0.001), and LVCR (HR: 0.524, 95% CI: 0.324-.647, p=0.008). The annual mortality rate was lowest (1.2%) in patients with a score of 0 (n=61) and highest (31.9%) in patients with a score of 5 (n=15, p<0.001). Conclusion High resting CFV predicts worse survival in ischemic and nonischemic HF with reduced EF. The value is independent and additive to resting EF, CFVR, LVCR, and inducible ischemia.

High resting coronary flow velocity and reduced coronary flow velocity reserve independently predict worse survival in diabetic patients without inducible ischemia and normal left ventricular function

Abstract Background High resting coronary flow velocity (CFV) in the mid-distal left anterior descending coronary artery (LAD) can be easily assessed with transthoracic echocardiography (TTE) and is a predictor of worse survival. Purpose In this study, we sought to assess the relationship between resting CFV, coronary flow velocity reserve (CFVR), and outcome in patients without inducible regional wall motion abnormality during stress echo (SE). Methods In a prospective multicenter study design, we enrolled 6,887 patients (age 65±11 years, 3,838 men, 1,963 diabetics), with left ventricular ejection fraction (LVEF) ≥50% referred for SE. Recruitment (years 2004-2022) involved 7 accredited laboratories, with inter-observer variability <10% for CFV measurement at study entry. Baseline peak diastolic CFV (abnormal value >32 cm/s) was obtained by pulsed-wave Doppler in mid-distal LAD. Coronary flow velocity reserve (CFVR, abnormal value ≤2.0) was assessed with dipyridamole. All-cause death was the only end-point. Results The mean CFV of LAD was 30±11 cm/s. The mean CFVR was 2.37±0.58. During a median follow-up of 6.0±4.2, 1,015 (15%) patients died. At Cox analysis, resting CFV >32 cm/s independently predicted mortality together with CFVR <2, age, diabetes, previous myocardial infarction, history of coronary surgery and LVEF. Resting CFV allowed effective risk stratification either in diabetics and nondiabetics although the difference in survival based on resting CFV was more marked in the former (Figure). In addition, it added significant (p<0.0001) prognostic information to CFVR result in the diabetic, but not in the non-diabetic population (Figure). Conclusion High resting CFV with TTE in mid-distal LAD predicts worse survival in patients without inducible ischemia. The value is independent and additive to CFVR in diabetic patients. The combination of high resting CFV-low CFVR is associated with worse survival.

Detection of left coronary ostial obstruction during transcatheter aortic valve replacement by coronary flow velocity measurement in the left main trunk by intraoperative transesophageal echocardiography

BackgroundCoronary obstruction is a rare but catastrophic complication of transcatheter aortic valve replacement (TAVR) and occurs mostly at the left coronary artery (LCA) ostium. However, some patients do not show any clinical findings, and thus, its detection is sometimes difficult. The peak diastolic flow velocity in left main coronary artery (LM) was reportedly increased in significant stenosis lesions. We evaluated the effectiveness of measuring blood flow velocities in LM by transesophageal echocardiography (TEE) for the detection of LCA ostial obstruction during a TAVR procedure. MethodsA total of 1105 consecutive patients who underwent TAVR in Sendai Kousei Hospital between September 2014 and December 2020 were enrolled. The LM blood flow velocity was measured at pre- and post-valve implantation. ResultsAmong the 1105 patients, 9 had LCA ostial obstruction. The peak LM blood flow velocity at post-TAVR [0.90 (0.39–1.15) vs. 0.37 (0.28–0.50) m/s; p = 0.0046) was significantly higher in 9 patients who had LCA ostial obstruction, compared with the remaining 1096 patients who had not (controls), although no significant difference was observed before the TAVR procedures between the two groups. The post- to pre-TAVR LM flow velocity ratio [2.26 (1.31–3.42) vs. 1.06 (0.82–1.36); p = 0.0030] was also significantly higher in patients with LCA obstruction, compared to the controls. Furthermore, the post- to pre-TAVR LM blood flow velocity ratio was >2.0 in all six hemodynamically stable patients with LCA obstruction, whereas <2.0 in all three patients with LCA obstruction who showed hemodynamic collapse at post-TAVR procedure. ConclusionCoronary blood flow velocity in LM significantly increased in hemodynamically stable LCA obstruction patients. The intraprocedural TEE measurement of the LM flow velocities would be potentially useful to detect asymptomatic and hemodynamically stable LCA ostial obstruction.

Invasive methods for coronary reserve measurement

During the last years, following numerous trials, the need of functional assessment of stenoses before myocardial revascularization has been established. This came to replace the subjective approach based on the so-called “oculo-stenotic” reflex of the operator. Numerous methods for coronary reserve (CR) estimation as a measure of functional significance of the lesion, have been introduced in the practice. Those methods are noninvasive and invasive. A part of them are based on the measurement of coronary flow velocity before and after hyperemic medication, other are based on the difference of arterial pressure before and after the coronary stenosis. They are divided to such with or without hyperemic medication. During the last years in the diagnostic have been used methods for functional estimation of the lesions based only on standard coronary angiography or even computerized tomography (CT). The aim of this article is to present a review of modern invasive methods for coronary reserve measurement.

Dynamics of coronary artery velocity flow during exercise echocardiography

Purpose The aim of our study was to acquire non-invasive data from coronary flow velocity profiles during exercise in groups of healthy subjects and of patients with arterial hypertension. Material and Methods We enrolled 83 patients into two groups: (1) 35 non-selected consecutive healthy subjects; (2) 25 consecutive patients with arterial hypertension. All the patients performed supine bicycle symptoms-limited tests. Throughout exercise the diastolic peaks of coronary flow velocity in LAD were recorded. Coronary flow velocity reserve (CFVR) was calculated off-line. Profiles of coronary artery velocity were acquired for all groups. The coronary artery flow parameters investigated were comparable in healthy and hypertensive patients at every stage. Results The average diastolic velocities were 54.8 ± 12.9 vs. 51.8 ± 12.2 cm/s, at 50 W; 69.2 ± 17.1 vs 64.4 ± 19.1 cm/s at 75 W; 70.7 ± 16.4 vs. 76.1 ± 19.0 cm/s at 100 W; 80.0 ± 16.0 vs. 72.9 ± 16.1 cm/s at 125 W; 83.7 ± 12.2 vs. 81.4 ± 17.0 at 150 W, p- non-significant, respectively. On average, the healthy group reached CFVR > 2.0 at a heart rate of 110–120 beats/min at 75 W. During supine bicycle exercise, healthy subjects and patients with arterial hypertension have a similar coronary artery flow velocity profile. Conclusion The routine exercise echocardiography test can feasibly be supplemented with the additional measurement of coronary flow velocity during routine supine exercise stress tests, as the normal range of CFVR is reached before submaximal heart rate.

Evaluation of effects of cardiac resynchronization on coronary blood flow by coronary flow reserve and in patients with İdiopathic dilated cardiomyopathy: Does it predict the response?

Background: The results of previous studies evaluating the effects of cardiac resynchronization therapy (CRT) on myocardial blood flow (MBF) and their relation with the response to CRT are conflicting. Materials and Methods: Sixty-one patients diagnosed with idiopathic dilated cardiomyopathy (IDC), a functional capacity (New York Heart Association [NYHA]) Class II or III, and left bundle branch block (LBBB) (QRS width >150 ms) were enrolled in the study. We aimed to evaluate the effects of CRT on MBF in patients with IDC and LBBB by coronary flow reserve (CFR) measurements and thereby tried to predict the responders. Results: Sixty-one patients with IDC were enrolled. CFR and hyperemic fractional flow reserve (FFR) increased after CRT. The only parameter affecting the increase in CFR was the change in FFR after CRT. Then, 44 patients who responded to the CRT treatment at 6 months were compared with 17 patients who did not. Left ventricle outflow tract time-velocity integral (LVOT-TVI), stroke volume (SV) and cardiac output index (COi) was detected significantly higher also left ventricular end-diastolic pressure (LVEDP) was lower in the CRT responders. However, there were no significant differences in coronary flow velocity measurements between the two groups. Moreover the regression analysis revealed that the baseline NYHA class, LVOT TVI, SV, COi, and LVEDP, which were changed due to increased blood flow after CRT implantation, is not associated with response to CRT. Conclusions: Our results suggest that MBF increased after CRT in patients with IDC probably by improving microvascular functions. However, the response to CRT treatment is not related to the changes in the coronary blood flow velocities after CRT.

Abstract 13792: Association of Immunocompromised State With Coronary Microvascular Dysfunction in Patients With Well-controlled HIV

Introduction: Patients with HIV have an elevated risk of cardiovascular disease (CVD) that may be partially driven by inflammation and residual immune dysfunction despite treatment with antiretroviral therapy (ART). Coronary microvascular dysfunction (CMD) is an important pathophysiological link between inflammation, immune dysfunction, and CVD and may provide mechanistic insight into CVD risk among HIV+ patients. Methods: We recruited 3 groups of adults aged 40-80 years free of CVD: HIV with evidence of prior/current immunocompromise (n=17), HIV without immunocompromise (n=19), and HIV- controls. All HIV+ participants were on ART and had suppressed viral loads. All controls were on HIV pre-exposure prophylaxis (PrEP). Immunocompromise was defined as nadir CD4 count &lt;200 cells/μL or current CD4 count &lt;500 cells/μL. Participants underwent Doppler echocardiography with coronary flow velocity measurement in the distal left anterior descending coronary artery at rest and during adenosine infusion. CMD was defined as coronary flow reserve (CFR) &lt; 2.50. Multivariable linear regression models assessed the association of HIV group with CFR. Results: Of 51 individuals who underwent CFR testing, median (IQR) age was 54 (46-58) and 92% were male. CFR was 3.71 (2.90-4.72) in controls, 3.49 (2.52-4.20) in HIV+/ immunocompromise-, and 2.35 (2.12-2.92) in HIV+/ immunocompromise+ (p=0.002). CMD was present in 7% of controls, 21% of HIV+/immunocompromise-, and 53% of HIV+/immunocompromise+ (p= 0.01). Compared with controls, HIV+/immunocompromise+ was significantly associated with lower CFR after multivariable adjustment ( Table ). Conclusions: HIV+ patients with current/prior immunocompromise free of CVD had high prevalence of CMD and had significantly lower CFR compared with controls on PrEP. Future studies should investigate CMD as a possible target for CVD prevention in HIV+ patients, particularly those with a prior or current immunocompromised state.

Coronary flow response to remote ischemic preconditioning is preserved in old cardiac patients.

The effect of remote ischemic preconditioning (RIPC) on coronary flow in elderly cardiac patients has not been investigated yet. Thus, we aimed to study the change of coronary flow subsequent to RIPC in old patients with heart diseases and to identify its main correlates. Ninety-five elderly patients (aged ≥ 65years) accessing cardiac rehabilitation ward underwent transthoracic ultrasound evaluation of peak diastolic flow velocity of left anterior descending artery. Measurements of coronary flow velocity were performed on baseline and after an RIPC protocol (three cycles of 5min ischemia of right arm alternating 5min reperfusion). Differences between subjects with coronary flow velocity change over or equal the 75° percentile (high-responders) and subjects with a coronary flow velocity change under the 75° percentile (low-responders) were assessed. In enrolled elderly heart patients, coronary flow velocity significantly augmented from baseline after RIPC [0.23m/s (0.18-0.28) vs 0.27m/s (0.22-0.36); p < 0.001 by Wilcoxon test]. High-responders to RIPC were significantly younger and in better functional status than low-responders. Heart failure resulted as the main variable associated with impairment of RIPC responsiveness (R 2 = 0.202; p = 0.002)]. Our sample of old cardiac patients presented a significant median increment of coronary flow velocity after RIPC. The magnitude of the observed change of coronary flow velocity was comparable to that previously described in healthy subjects. The coronary response to RIPC was attenuated by heart failure. Further research should define whether such RIPC responsiveness is associated with cardioprotection and carries prognostic implications.

Effects of nitroglycerine on coronary flow velocity before and during adenosine provocation.

BackgroundTransthoracic echocardiography-assessed coronary flow velocity reserve (CFVR) evaluates coronary microvascular arterial function. Coronary flow velocity measurements at baseline and during hyperemia are used to calculate CFVR. Adenosine infusion induces hyperemia but it is not known if it causes a maximal response. We hypothesized that pre-treatment with nitroglycerine before adenosine provocation enhances hyperemia.MethodsTwenty-three healthy study subjects (mean age 27.5 ± 5.5, 35% women) underwent CFVR measurements before and after pretreatment with sublingual nitroglycerine (0.5 mg). Hyperemia was induced by adenosine infusion (140 μg/kg/min). In addition, the effect of nitroglycerin on left main coronary artery diameter was assessed.ResultsPretreatment with nitroglycerine increased median CFVR from 3.6 (range 2.8–4.3) to 5.0 (4.1–6.0), p = 0.002. The increase was caused by a marked reduction in baseline coronary flow velocity 17 (15–24) vs 27 (19–31) cm/s, p < 0.0001) while hyperemic velocity remained unchanged (90 (68–116) vs 93 (75–105) cm/s, p = 0.48). Nitroglycerin significantly dilated the left main coronary artery (from median 3.1 (2.7–3.6) mm to 3.8 (3.1–4.3) mm, p = 0.018).ConclusionPretreatment with nitroglycerine dilates coronary arteries and increases coronary flow velocity reserve indicating that adenosine alone causes a submaximal hyperemia.

Is the presence of AA amyloidosis associated with impaired coronary flow reserve?

Background and aimsSystemic amyloid A protein (AA) amyloidosis may occur as a complication of many chronic inflammatory disorders. Patients receiving inadequate anti-inflammatory and immunosuppressive therapies have an increased risk of developing systemic AA amyloidosis. Inflammation plays a role in all stages and the thrombotic complications of atherosclerosis. In the absence of epicardial coronary stenosis, coronary flow reserve (CFR) reflects coronary microvascular dysfunction. In the present study, we hypothesized that amyloid advanced subclinical inflammation in chronic inflammatory diseases (CID) patients may further affect coronary microcirculation. MethodsThirty-two patients with biopsy-diagnosed renal AA, 73 patients with non-amyloid CID, and a group of healthy volunteers were included in the study. The measurements of coronary flow velocity were performed by a single investigator with expertise in transthoracic Doppler harmonic echocardiography (TTDE). ResultsThe AA amyloidosis subgroup had significantly lower CFR values than other non-amyloid CID patients and the control individuals (1.8 (1.5–2.1) vs. 2.1 (2.0–2.4) and 3.0 (2.8–3.2), p < 0.001). Multivariate logistic regression analysis indicated that the presence of AA amyloidosis and elevated hs – CRP independently predict impairment of the CFR (p < 0.05). ConclusionsThe presence of AA amyloidosis is related to decreased CFR values and the presence of AA amyloidosis and elevated hs – CRP independently predict impairment of the CFR. Therefore, patients with AA amyloidosis may have an increased risk of developing coronary artery diseases.

Abstract O.57: Coronary Circulation Assessed by Transthoracic Echocardiography during Exercise Test is Impaired in Patients after Kawasaki Disease Even with Regressed Coronary Arterial Lesions

Background: Coronary flow reserve (CFR) has important clinical implications for the evaluation of coronary circulation including Kawasaki disease (KD). Pharmacological vasodilation is generally used to induce hyperemia for the assessment of CFR; however, exercise test provides more physiological stress. Objectives: This study sought to assess CFR during exercise in patients after KD with regressed coronary arterial lesions (CALs) by transthoracic echocardiography (TTE). Methods: Twenty KD patients were studied, comprising 8 patients with regressed CALs in the left anterior descending coronary artery (LAD) and 12 patients without CALs (median ages; 10 and 9 years, respectively). Fourteen age-matched healthy subjects were also studied as controls. We obtained peak diastolic coronary flow velocity (CFV) of the LAD by pulsed-Doppler TTE at rest and at submaximal exercise on supine ergometer. CFR was calculated as the ratio of exercise to rest CFVs. Results: The CFV measurements were obtained in all the subjects. There was no significant difference in the CFVs among the patients with regressed CALs, those without CALs and the controls (30 ± 7 vs. 31 ± 10 vs. 28 ± 8 cm/s, respectively). The CFVs increased during exercise in the patients without CALs and the controls (51 ± 11 and 49 ± 10 cm/s, respectively, both p &lt;0.05). In consequence, the CFR was lower in the patients with regressed CALs compared with those without CALs and the controls (1.3 ± 0.2 vs. 1.7 ± 0.2 and 1.7 ± 0.2, respectively, p &lt;0.05). Conclusions: Exercise test demonstrated impaired CFR in KD patients with regressed CALs. It suggests that these patients have risk of future myocardial ischemic events.

Effects of intravenous atrial natriuretic peptide and nitroglycerin on coronary vasodilation and flow velocity determined using 3 T magnetic resonance imaging in patients with nonischemic heart failure

Although atrial natriuretic peptide (ANP) is widely used in patients with congestive heart failure (CHF), little is known about its effect on epicardial coronary arteries. Magnetic resonance imaging (MRI) enables precise measurement of coronary vasodilation and flow velocity. In this study, we examined the changes in epicardial coronary artery size and flow velocity in response to intravenous infusion of ANP or nitroglycerin (NTG) by using 3 T MRI in patients with CHF. The study cohort contained a total of 14 subjects: 8 patients with CHF and 6 healthy volunteers as controls, randomly divided into two groups: the ANP group (0.03 μg/kg/min) and the NTG group (0.3 μg/kg/min). Cross-sectional MR angiography and phase-contrast flow velocity of the right coronary artery in the same in-plane slice were obtained at the baseline, during drug infusion, and at two subsequent time points after stopping drug infusion. A significant increase was observed in the coronary cross-sectional area at 15 min after drug infusion in both groups compared with that at baseline; however, a late peak was observed at 15 min after stopping infusion in the ANP group. No significant differences were detected in the flow velocity in both groups. Furthermore, although NTG increased the heart rate, this change was not found in the ANP group. Coronary vasodilation and flow velocity can be measured simultaneously using 3 T MRI. Using this method, we showed that the effects of ANP on the coronary artery vasodilation and flow velocity were not inferior to those of NTG, with no significant alteration in heart rate.

Role of Noninvasive Imaging in the Diagnosis of Cardiac Allograft Vasculopathy

Cardiac allograft vasculopathy (CAV) is common, with a prevalence of 52% at 10 years after transplantation, and represents a leading cause of death beyond the first year, responsible for approximately 15% of deaths annually.1 It is characterized by diffuse and concentric intimal proliferation, typically involving the intramural as well as epicardial coronary arteries. Its diagnosis is difficult to establish clinically because of denervation of the transplanted heart. Consequently, it presents late with silent myocardial infarction, progressive heart failure, or arrhythmic sudden death.2 Screening is therefore required for its early detection. Although coronary intravascular ultrasound (IVUS) is considered the gold-standard technique for detecting the anatomic features of CAV (Table 1), its broad clinical use in this context is limited by cost and lack of widespread expertise, and its evaluation is limited to epicardial vessels.3 Coronary angiography, performed annually or biannually, remains the most common clinical screening method.4 However, because of the diffuse nature of CAV with a lack of normal reference segments and the relatively late occurring luminal narrowing, the sensitivity of angiography is as low as 30% when compared with IVUS (Figure 1).5 As a result, complications frequently occur before disease is evident angiographically.6 Furthermore, angiography is associated with significant albeit uncommon complications (overall complication rate, 7.4/1000 procedures, including rates of 0.65/1000, 1.6/1000, and 0.72/1000 for cerebrovascular accidents, vascular complications, and death, respectively), is disliked by transplant recipients, is costly, and repeated studies are associated with an important cumulative radiation dose.7 View this table: Table 1. Stanford Classification of CAV Severity on IVUS Figure 1. Invasive assessment of cardiac allograft vasculopathy (CAV) in a patient with severe disease, highlighting the limited sensitivity of conventional coronary angiography. Although no left anterior descending (LAD) flow-limiting stenoses are seen on angiography ( A ), intravascular ultrasound ( B ) shows significant intimal thickening, measuring up to …

New method to measure coronary velocity and coronary flow reserve

Coronary flow reserve (CFR) is an important index of coronary microcirculatory function. The objective of this study was to validate the reproducibility and accuracy of intravascular conductance catheter-based method for measurements of baseline and hyperemic coronary flow velocity (and hence CFR). The absolute coronary blood velocity was determined by measuring the time of transit of a saline injection between two pairs of electrodes (known distance) on a conductance catheter during a routine saline injection without the need for reference flow. In vitro validation was made in the velocity range of 5 to 70 cm/s in reference to the volume collection method. In 10 swine, velocity measurements were compared with those from a flow probe in coronary arteries at different CFR attained by microsphere embolization. In vitro, the mean difference between the proposed method and volume collection was 0.7 ± 1.34 cm/s for steady flow and -0.77 ± 2.22 cm/s for pulsatile flow. The mean difference between duplicate measurements was 0 ± 1.4 cm/s. In in vivo experiments, the flow (product of velocity and lumen cross-sectional area that is also measured by the conductance catheter) was determined in both normal and stenotic vessels and the mean difference between the proposed method and flow probe was -1 ± 12 ml/min (flow ranged from 10 to 130 ml/min). For CFR, the mean difference between the two methods was 0.06 ± 0.28 (range of 1 to 3). Our results demonstrate the reproducibility and accuracy of velocity and CFR measurements with a conductance catheter by use of a standard saline injection. The ability of the combined measurement of coronary lumen area (as previously validated) and current velocity and CFR measurements provides an integrative diagnostic tool for interventional cardiology.

Measurements of variations in resting coronary flow velocity

The recent development of intracoronary Doppler catheters has allowed the measurements of coronary flow velocity and coronary flow reserve. To assess the presence of spontaneous variability in resting coronary flow velocity, which should be taken into account in investigation the effects of various interventions on the coronary circulation, the authors studied 20 syndrome X patients (group 1), 8 patients with coronary artery disease (group 2), and 10 heart transplant patients (group 3) who were undergoing coronary flow reserve studies. With a standard femoral approach a 3.6F intracoronary Doppler catheter was positioned in the proximal left anterior descending coronary artery.The coronary flow velocity was measured over a fifteen-minute period with the patient in the supine position and breathing normally. There were no significant changes in the coronary flow velocity during the study in all three groups. These results demonstrate that under resting conditions, with stable heart rates and mean arterial pressures, the coronary flow velocity remains relatively constant and any changes observed under these conditions as a result of any intervention are likely to be related to the intervention.

Ivabradine improves coronary flow reserve in patients with stable coronary artery disease

ObjectivesAlthough treatment with ivabradine reduces the incidence of hospital admissions for myocardial infarction and coronary revascularisation, there are no data concerning its effect on coronary circulation. The purpose of this study was to assess the effects of ivabradine on coronary flow velocity and flow reserve (CFR) in patients with stable coronary artery disease (CAD). MethodsDuring diagnostic coronary angiography (baseline), twenty-one patients with stable CAD underwent coronary flow velocity measurements (APVcm/s) in a non-culprit vessel, using a Doppler guidewire, at rest (r) and after adenosine administration to achieve maximal hyperaemia (h). During programmed coronary intervention in the culprit vessel, the same measurements were repeated one week after treatment with ivabradine (5mg twice daily), both at the intrinsic heart rate and at a paced heart rate identical to that before treatment. CFR was defined as h-APV/r-APV. ResultsHeart rate was significantly lower after treatment with ivabradine (78±14bpm vs 65±9bpm, p<0.001). Also, a reduction of r-APV (17.0±5.5 vs 19.7±7.6, p=0.003) and augmentation of h-APV (57.9±17.8 vs 53.5±21.4, p=0.009) leading to CFR improvement (3.51±0.81 vs 2.78±0.61, p<0.001) were observed. During pacing, although r-APV reverted to values similar to those before treatment (20.0±6.5 vs 19.7±7.6, p=NS), a sustained improvement in h-APV was observed (59.5±19.7 vs 53.5±21.4, p=0.007) and CFR remained higher than before treatment (3.04±0.66 vs 2.78±0.61, p<0.001). ConclusionsIvabradine treatment significantly improves hyperaemic coronary flow velocity and CFR in patients with stable CAD. These effects remain even after heart rate correction indicating improved microvascular function.

Clinical significance of coronary flow velocity measurement using transthoracic Doppler echocardiography for unstable angina: a two-case report.

Clinical significance of coronary flow velocity measurement by transthoracic Doppler echocardiography in 2 patients with unstable angina (UA) was reported. No significant abnormality was observed on electrocardiography. Coronary flow sequence of the left anterior descending coronary artery (LAD) was detected in diastole. Peak diastolic flow velocity was 11.1cm/s in case 1 and 10.1cm/s in case 2. On the basis of these data, emergency coronary angiography was performed in both cases. Severe stenosis was observed at the proximal portion of LAD; consequently, emergency coronary angioplasty was performed. Coronary flow velocity measurement is useful as a diagnostic strategy in UA.

SL7 Clinical Value of Coronary Flow Velocity Measurement by Transthoracic Doppler Echocardiography

SL7 Clinical Value of Coronary Flow Velocity Measurement by Transthoracic Doppler Echocardiography