Derya Tok

High Serum Bilirubin Concentrations Preserve Coronary Flow Reserve and Coronary Microvascular Functions

Background—Elevated serum bilirubin concentrations protect against atherosclerotic diseases; however, it is not clear whether higher serum bilirubin concentrations in physiological ranges work in favor of the cardiovascular system in younger persons with no cardiovascular risk factors. Accordingly, we investigated the effects of high, intermediate, and low serum bilirubin concentrations on coronary flow reserve (CFR). Methods and Results—Fifty-two healthy subjects with hyperbilirubinemia (total bilirubin 1.43±0.33 mg/dL; mean age 35.9±7.3), 55 subjects with intermediate bilirubin level (total bilirubin: 0.69±0.11 mg/dL; mean age: 36.4±6.8), and 53 healthy subjects with hypobilirubinemia (total bilirubin 0.37±0.08 mg/dL; mean age, 37.6±6.6) were studied. Transthoracic second harmonic Doppler echocardiography examination was performed using an Acuson Sequoia C256 Echocardiography System. Coronary diastolic peak flow velocities were measured at baseline and after dipyridamole infusion (0.84 mg/kg over 6 minutes). CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocities. Demographic features, coronary risk factors, echocardiographic measurements, and biochemical measurements were similar among the 3 groups, except high-sensitivity C-reactive protein (hsCRP). CFR values were significantly higher in subjects with high bilirubin concentrations than those were in the intermediate and the low bilirubin groups (3.19±0.73; 2.75±0.42; 2.56±0.52, respectively; P<0.0001), and hsCRP levels were significantly lower in subjects with high bilirubin concentrations than those in both intermediate and low bilirubin groups (1.4±1.0, 2.0±1.7, 3.0±1.9 mg/L, respectively; P<0.001). hsCRP levels correlated with total bilirubin concentration and with CFR. Conclusion—Elevated serum bilirubin concentrations protect from CFR impairment, coronary microvascular dysfunction, and possibly coronary atherosclerosis.

Impaired Coronary Flow Reserve in Hemodialysis Patients: A Transthoracic Doppler Echocardiographic Study

Background: Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work. In this study, CFR of hemodialysis patients with angiographically normal coronary arteries was evaluated using transthoracic second harmonic Doppler echocardiography. Methods and Results: Ten hemodialysis patients, and 14 sex-, age- and left ventricular mass index-matched hypertensive controls with angiographically normal coronary arteries underwent transthoracic second harmonic Doppler echocardiographic examination. Coronary basal diastolic peak flow velocities and hyperemic peak flow velocities after dipyridamole infusion (0.56 mg/kg over 4 min) were measured. CFR was defined as the ratio of hyperemic to basal diastolic peak velocities. CFR ≧2.0 was regarded as normal. Additionally, Doppler tissue imaging pulse wave measurements were taken from the lateral and septal corners of the mitral annulus. CFR values were significantly lower in the study group than in the control group (2.03 ± 0.3 vs. 2.61 ± 0.5, p = 0.005). In 5 of 10 hemodialysis patients, CFR was <2.0 (50%), however in only 1 of 14 control patients it was <2.0 (5%). Conclusions: Impairment of coronary microvasculature occurs earlier in patients with chronic renal failure and may be the harbinger of subsequent primary uremic myocardial disease. In patients with chronic renal failure and normal coronary arteries, decreased CFR by transthoracic echocardiography might be regarded as an early finding of an affected coronary vasculature.

Metformin therapy improves coronary microvascular function in patients with polycystic ovary syndrome and insulin resistance

Background  Women with polycystic ovary syndrome (PCOS) are thought to have increased cardiovascular risk. Metformin therapy reduces whole‐body insulin resistance (IR) in patients with type‐2 diabetes mellitus (DM).

Different effects of atenolol and nebivolol on coronary flow reserve

Atenolol and nebivolol are commonly used antihypertensive agents. Nebivolol increases both stimulated and basal release of endothelial nitric oxide, thereby improving flow-mediated dilatation of the brachial artery in patients with essential hypertension.1 However, it is believed that atenolol has no effect on arterial vasoreactivity.1 Pharmacological stress transthoracic second harmonic Doppler echocardiography (TTDE) is a useful tool in evaluating coronary flow reserve (CFR). Several studies have evaluated its feasibility.2 We hypothesised that in patients with essential hypertension, nebivolol can reverse coronary microvascular dysfunction and improve CFR. After one month of lifestyle changes, 63 consecutive patients with hypertension had 24 h ambulatory blood pressure monitoring. Hypertension was diagnosed in 30 of these who had average daytime blood pressure > 135/85 mm Hg and average night-time blood pressure > 125/75 mm Hg. These 30 patients constituted the study population. For the control group, 30 healthy volunteers were enrolled. Patients with known cardiovascular risk factors, those who were taking any vasoactive or hypertension drug, and those with ECG changes specific for myocardial ischaemia were excluded from the study. Written informed consent was obtained from each participant, and the institutional ethics committee approved the …

Elevated serum uric acid levels impair coronary microvascular function in patients with idiopathic dilated cardiomyopathy

In patients with idiopathic dilated cardiomyopathy (IDC), attenuated coronary flow reserve (CFR) and elevated serum uric acid levels have been reported. In this study, we investigated whether increased uric acid levels correlate with the degree of coronary microvascular dysfunction.

Coronary flow reserve is preserved in white-coat hypertension

Objectives: To assess the possible influence of white-coat hypertension (WCH) on coronary flow reserve (CFR). Methods: CFR was measured by means of transthoracic second harmonic Doppler echocardiography in 29 patients with WCH, 32 patients with sustained hypertension and 35 healthy volunteers. Results: CFR was significantly lower in the sustained hypertension group than in the WCH and the control groups, but it was not different between the WCH and the control groups (2.40 (SD 0.54), 2.77 (0.41) and 2.83 (0.60), respectively). Conclusion: CFR is preserved in patients with WCH.