Increased hemoglobin A1c level associates with low left atrial appendage flow velocity in patients of atrial fibrillation.

BACKGROUND AND AIMS: High hemoglobin A1c (HbAlc) level is associated with increased cardiovascular disease risk and thromboembolic events [1]. The study sought to explored the association between HbAlc and left atrial appendage flow velocity (LAAV) among non-valvular atrial fibrillation (AF) patients. METHODS AND RESULTS: A total of 249 consecutive non-valvular AF patients who underwent transesophageal echocardiography (TEE) were divided into two subgroups according to the median of LAAV level (<45 cm/s, ≥45 cm/s). Blood samples and other baseline clinical data of all patients were collected and analyzed. The low LAAV group included 126 patients and the high LAAV group included 123 patients. Patients in the low LAAV group were older and had a higher percentage of persistent AF, chronic heart failure, and higher CHA2DS2-VASc score (P < 0.05). HbAlc level in the low LAAV group was significantly higher than the high LAAV group [6.1 (5.7-6.5)% vs 5.9 (5.6-6.2)%, P = 0.010]. The low LAAV group had larger left atrial diameter (LAD), left atrial area (LAA), higher left atrial pressure (LAP), and lower left ventricular ejection fraction (LVEF) (P < 0.05). Spearman rank correlation analysis showed that the HbAlc level was negatively correlated with LAAV (r = -0.211, P = 0.001). Multivariate analysis indicated that female gender (OR = 2.233, 95% CI 1.110-4.492, P = 0.024), persistent AF (OR = 6.610, 95% CI 3.109-14.052, P < 0.001), and HbAlc (OR = 1.903, 95% CI 1.092-3.317, P = 0.023) were independent factors that associated with low LAAV in AF patients. CONCLUSION: Increased HbAlc level is associated with decreased LAAV and may reflect a low contractile function of the left atrial appendage.

Numerical analysis of aortic hemodynamics under the support of venoarterial extracorporeal membrane oxygenation and intra-aortic balloon pump.

BACKGROUND AND OBJECTIVE: A gap still exists in the hemodynamic effect of intra-aortic balloon pump (IABP), venoarterial extracorporeal membrane oxygenation (VA-ECMO), and VA-ECMO plus IABP on the blood perfusion of the coronary artery, brain, and lower limb; the relation between heart flow and ECMO flow; and the wall stress of vessels. METHODS: A finite-element model of the aorta, ECMO, and IABP was proposed to calculate the mechanical response via fluid-structure interaction. Heart failure (HF), IABP, ECMO, and ECMO plus IABP were utilized to study the effect of support models. RESULTS: For the pressure curve, VA-ECMO weakened the dicrotic notch of pressure compared with HF and the pulsatile index (0.494 vs. 0.706 vs. 0.471 vs. 0.613). IABP, ECMO, and ECMO plus IABP increased the perfusion of the coronary, brain, and renal artery compared with HF. However, ECMO and ECMO plus IABP clearly reduced the blood flow of the left arteria femoralis compared to that of the right arteria femoralis (ECMO: 194.04 vs. 730.80 mL/min; ECMO plus IABP: 342.15 vs. 947.22 mL/min). In addition, the flow of ECMO accessed the renal artery more than the left ventricular flow. Greater ventricular flow perfused to the renal artery at a diastolic period for ECMO plus IABP, especially at the time points of 2.192 s and 2.304 s. Compared to the velocity distribution with ECMO, the flow of the right arteria femoralis was increased in the process of IABP-on. According to these four cases, the stress of the vascular wall was increased for ECMO support at the systolic period. The peak wall stress of ECMO is increased by 20% at 1.68 s. CONCLUSIONS: ECMO plus IABP is more conducive to the blood supply than other cases from the result of numerical simulation. The location of blood intersection was generated in the region of the renal artery, which is estimated carefully.

Left ventricular filling pressure assessed by exercise TDI was correlated with early HFNEF in patients with non-obstructive hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) patients are more susceptible to suffer from heart failure with normal ejection fraction (HFNEF). Therefore, it is critical to evaluate the relationship between left ventricular filling pressure (LVFP) and HFNEF, even if a large proportion of HCM patients have normal LVFP at rest. The objective was to assess the correlation between exercise tissue Doppler imaging (TDI) and early HFNEF in HCM patients by treadmill exercise echocardiography combined with cardiopulmonary exercise test (CPET). METHOD: Twenty-seven non-obstructive HCM patients and 31 age- and gender-matched healthy volunteers were enrolled in this study. All subjects underwent treadmill exercise echocardiography combined with CPET. N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were analyzed before and after exercise. RESULT: Five HCM patients had normal LVFP at rest and increased after exercise. For this subgroup, the relationship between minute ventilation and carbon dioxide production (VE/VCO2 slope) and NT-proBNP levels were higher compared with controls and the subgroup with normal resting and stress LVFP, but was similar to the subgroup with elevated LVFP both at rest and after exercise. CONCLUSION: Elevated LVFP after exercise suggested the occurrence of early HFNEF in patients with non-obstructive HCM.

[Correlation of large artery stiffness and coronary flow velocity reserve].

OBJECTIVE: Coronary flow velocity reserve (CFVR) is an important indicator of coronary endothelial functions and microcirculation. Pulse wave velocity (PWV) reflects the degree of aortic sclerosis and it is an independent predictor of cardiovascular events. The present study was designed to evaluate the correlation of large artery stiffness and CFVR. METHODS: A total of 101 consecutive subjects were enrolled to measure the brachial-ankle pulse wave velocity (baPWV). According to the presence or absence of higher baPWV (> 1400 cm/s), they were divided into 2 groups. Transthoracic echocardiography was employed to measure coronary flow velocity in coronary left anterior descending (LAD). Then after an intravenous infusion of adenosine triphosphate, the velocity of blood flow was measured when the vessel was in maximal dilation. The ratio of flow velocity of those in maximal dilation to those at rest was CFVR. RESULTS: The subjects with a higher baPWV (> 1400 cm/s) were markedly elder and had higher risks of hypertension and diabetes. Thus age, hypertension and diabetes contributed to arteriosclerosis. More importantly, the subjects with a higher baPWV (> 1400 cm/s) had a much lower level of CFVR (2.66 ± 0.74 vs 2.95 ± 0.76; P < 0.01) than those with a lower baPWV (< 1400 cm/s). Furthermore correlation analysis showed that CFVR and baPWV levels were significantly negatively correlated (r = -0.35, P < 0.01). CONCLUSIONS: A negative correlation exists between artery stiffness and coronary flow velocity reserve. The increased vascular stiffness may impair coronary endothelial function, cause the dysfunction of coronary microcirculation and raise the risks of cardiovascular events.

[Left ventricular flow vector characteristics and the relationship between flow vector and left ventricular systolic function in patients with anterior myocardial infarction].

OBJECTIVE: To assess left ventricular vortex and flow vector features and the relationship between vector flow and left ventricular systolic function in patients with anterior myocardial infarction by echocardiography-derived vector flow mapping (VFM). METHODS: Echocardiography was performed in 31 patients with anterior myocardial infarction and 20 healthy controls. Flow vector and velocity of left ventricle were analyzed on apical 3 chambers view with color Doppler. RESULTS: (1) Left ventricular intracavitary vortex during isovolumic contraction phase could be detected in both groups. Vortex was detectable also during contraction phase and relaxation phase in patients with myocardial infarction. There was no vortex during contraction phase, and there was only small and transit vortex during relaxation phase in control group. (2)Flow vector of apex and middle segments directed to apex and was opposite to that of basal segment of left ventricle in patients with myocardial infarction and in controls [(10.6 ± 8.3) cm/s vs. -(5.8 ± 7.2) cm/s, (19.5 ± 11.8) cm/s vs. -(16.6 ± 14.7) cm/s]. During rapid relaxation phase, the velocity in apex was lower in patients with myocardial infarction than that in control group [(6.8 ± 9.8) cm/s vs. (17.6 ± 15.8) cm/s, P < 0.01]. (3) There was a negative correlation between velocity in apex and left ventricular ejection fraction (LVEF) during rapid eject phase in patients with anterior myocardial infarction (r = -0.52, P < 0.05). Velocity in apex of patients with LVEF < 50% was higher than that of patients with LVEF ≥ 50% during rapid eject phase [(13.5 ± 9.0) cm/s vs. (5.8 ± 5.1) cm/s, P < 0.05]. CONCLUSIONS: Vortex period is prolonged in patients with anterior myocardial infarction compared to normal controls during whole cardiac cycle, flow vector of apex and middle segments is directed to apex during eject phase and there is a negative correlation between velocity in apex and LVEF during rapid eject phase in patients with anterior myocardial infarction.

Homocysteine impairs coronary artery endothelial function by inhibiting tetrahydrobiopterin in patients with hyperhomocysteinemia.

Hyperhomocysteinemia (HHcy) has been associated with impaired vascular endothelial function. Our previous study demonstrated significantly higher secretion of the chemokine monocyte chemoattractant protein-1 from monocytes in response to lipopolysaccharide in patients with HHcy. In the present study, we investigated whether coronary endothelial function was damaged in patients with chronic HHcy (plasma level of homocysteine >15 µmol/l) and, if so, whether this impaired endothelial function is induced by the uncoupling of endothelial nitric oxide synthase (eNOS). When tetrahydrobiopterin levels are inadequate, eNOS is no longer coupled to l-arginine oxidation, which results in reactive oxygen species rather than nitric oxide production, thereby inducing vascular endothelial dysfunction. The 71 participants were divided into two groups, control (n = 50) and HHcy (n = 21). Quantification of coronary flow velocity reserve (CFVR) was after rest and after adenosine administration done by noninvasive Doppler echocardiography. Plasma levels of nitric oxide and tetrahydrobiopterin were significantly lower in patients with HHcy than in controls (99.54 ± 32.23 vs. 119.50 ± 37.68 µmol/l and 1.43 ± 0.46 vs. 1.73 ± 0.56 pmol/ml, all P < 0.05). Furthermore, CFVR was significantly lower in the HHcy than the control group (2.76 ± 0.49 vs. 3.09 ± 0.52, P < 0.05). In addition, plasma level of homocysteine was negatively correlated with CFVR. Chronic HHcy may contribute to coronary artery disease by inducing dysfunction of the coronary artery endothelium. The uncoupling of eNOS induced by HHcy in patients with chronic HHcy may explain this adverse effect in part.

Assessment of coronary artery flow velocity pattern as a long-term predictor of left ventricular function and cardiac events after percutaneous coronary intervention in anterior acute myocardial infarction.

BACKGROUND: Coronary flow velocity (CFV) can be used to assess short-term left ventricular function recovery and the clinical prognosis of patients with acute myocardial infarction (AMI). We evaluated CFV as a predictor of long-term left ventricular function recovery and cardiac events in patients with anterior wall AMI. METHODS AND RESULTS: CFV pattern of the distal left anterior descending (LAD), wall motion score index (WMSI) and left ventricular ejection fraction (LVEF) were recorded at the points of time within 24 hours, 3 days, 6 months, and 3 years after percutaneous coronary intervention (PCI) in 50 consecutive patients with anterior wall AMI. The clinical data were collected. Patients were divided into two groups based on diastolic deceleration time (DDT) 3 days after PCI. Compared with 3 days, LVEF and WMSI in group A (DDT>600 ms, n=20) improved in 6 months and 3 years (p<0.01), but they were unchanged in group B (DDT< or =600 ms, n=30). The incidence of cardiac events was higher in group B than in group A during 6 months (p<0.01).With a 3-year follow up, the incidence of chronic heart failure was higher in group B than in group A (p=0.009). CONCLUSION: CFV could be used as a predictor of long-term left ventricular function recovery and cardiac events in patients with anterior wall AMI.