Differential effects of heat-not-burn and conventional cigarettes on coronary flow, myocardial and vascular function

We compared the effects of Heat-not-Burn cigarette (HNBC) to those of tobacco cigarette (Tcig), on myocardial, coronary and arterial function as well as on oxidative stress and platelet activation in 75 smokers. In the acute study, 50 smokers were randomised into smoking a single Tcig or a HNBC and after 60 min were crossed-over to the alternate smoking. For chronic phase, 50 smokers were switched to HNBC and were compared with an external group of 25 Tcig smokers before and after 1 month. Exhaled carbon monoxide (CO), pulse wave velocity (PWV), malondialdehyde (MDA) and thromboxane B2 (TxB2) were assessed in the acute and chronic study. Global longitudinal strain (GLS), myocardial work index (GWI), wasted myocardial work (GWW), coronary flow reserve (CFR), total arterial compliance (TAC) and flow-mediated dilation (FMD) were assessed in the chronic study. Acute HNBC smoking caused a smaller increase of PWV than Tcig (change 1.1 vs 0.54 m/s, p < 0.05) without change in CO and biomarkers in contrast to Tcig. Compared to Tcig, switching to HNBC for 1-month improved CO, FMD, CFR, TAC, GLS, GWW, MDA, TxB2 (differences 10.42 ppm, 4.3%, 0.98, 1.8 mL/mmHg, 2.35%, 19.72 mmHg%, 0.38 nmol/L and 45 pg/mL respectively, p < 0.05). HNBCs exert a less detrimental effect on vascular and cardiac function than tobacco cigarettes.Trial registration Registered on https://clinicaltrials.gov/ (NCT03452124, 02/03/2018).

Determination of Aortic Characteristic Impedance and Total Arterial Compliance From Regional Pulse Wave Velocities Using Machine Learning: An in-silico Study

In-vivo assessment of aortic characteristic impedance (Zao) and total arterial compliance (CT) has been hampered by the need for either invasive or inconvenient and expensive methods to access simultaneous recordings of aortic pressure and flow, wall thickness, and cross-sectional area. In contrast, regional pulse wave velocity (PWV) measurements are non-invasive and clinically available. In this study, we present a non-invasive method for estimating Zao and CT using cuff pressure, carotid-femoral PWV (cfPWV), and carotid-radial PWV (crPWV). Regression analysis is employed for both Zao and CT. The regressors are trained and tested using a pool of virtual subjects (n = 3,818) generated from a previously validated in-silico model. Predictions achieved an accuracy of 7.40%, r = 0.90, and 6.26%, r = 0.95, for Zao, and CT, respectively. The proposed approach constitutes a step forward to non-invasive screening of elastic vascular properties in humans by exploiting easily obtained measurements. This study could introduce a valuable tool for assessing arterial stiffness reducing the cost and the complexity of the required measuring techniques. Further clinical studies are required to validate the method in-vivo.

Distinct Contribution of Systemic Blood Flow to Hypertension in an African Population Across the Adult Lifespan

Although hypertension in groups of African ancestry is volume-dependent, the relative impact of systemic flow (stroke volume, peak aortic flow [Q]) versus vascular mechanisms (systemic vascular resistance, aortic characteristic impedance [Zc], total arterial compliance) components of arterial load has not been evaluated across the adult age range. In participants of African ancestry (n=824, age=16–99 years, 68.3% female), using central arterial pressure and aortic velocity and diameter measurements in the outflow tract, we determined the hemodynamic correlates of age-related increases in blood pressure. Strong independent positive relations between age and stroke volume or peak aortic Q were noted ( P <0.0001), effects associated with ventricular end diastolic volume and aldosterone-to-renin ratios. Age-related increases in mean arterial pressure were associated with stroke volume and not systemic vascular resistance. Although age-Q relations began from early adulthood, initially an inverse association between age and aortic Zc ( P <0.0001) driven by increments in aortic root diameter ( P <0.0001) prevented an enhanced systolic blood pressure and pulse pressure. When Zc began to positively relate to age ( P <0.0001), age-Q relations translated into increases in forward wave pressures and hence systolic blood pressure and pulse pressure. Age relations with pulse pressure were as strongly determined by Q as by Zc or total arterial compliance (0.027±0.001 versus 0.028±0.001 and 0.032±0.003 mm Hg per yearly increase in pulse pressure produced by Q, Zc, and total arterial compliance; P <0.0001). Uncontrolled hypertension (confirmed with 24-hour blood pressure) was determined more by Q, Zc, and total arterial compliance than by increases in systemic vascular resistance ( P <0.0005 for comparison). In conclusion, relationships between age and systemic blood flow contribute markedly to hypertension in groups of African origins.

P2258Pulse wave velocity, total arterial compliance, and cardiac structure and function in late life

Background Coupled abnormalities in arterial and left ventricular (LV) stiffness characterize aging and heart failure with preserved ejection fraction. We hypothesized that two measures of aortic stiffness, pulse wave velocity (PWV; reflecting segmental arterial wall stress in late systole) and total arterial compliance (TAC; reflecting distensibility of entire arterial system) differentially relate to cardiac structure and function in the elderly. Methods Among participants in the Atherosclerosis Risk In Community (ARIC) study, we assessed the cross-sectional relationship of carotid-femoral PWV (cfPWV) and TAC with echocardiographic measures of cardiac structure and function using multivariable linear regression adjusting for demographics and co-morbidities. TAC defined as stroke volume over pulse pressure [mL/mmHg]. Exclusions were LVEF <50%, prevalent HF, ≥moderate valvular disease. Results Of the 4,141 participants included in this study, mean age was 75±5 years, 41% were male, and 80% were white. Mean values were: cfPWV: 11.7±3.4 m/sec; TAC: 1.1±0.3 mL/mmHg. Greater cfPWV was associated with greater LV mass, worse systolic function, and worse diastolic function (Table). In contrast, worse TAC was not related to LV structure and did not demonstrate consistent relationships with measures of LV diastolic function, but was associated with worse LV longitudinal strain. Echo measures cfPWV (1SD increase) TAC (1SD decrease) β Coefficient p-value β Coefficient p-value Cardiac structure Mean wall thickness, cm 0.10 <0.001 -0.01 0.499 LVMI, g/m2 0.04 0.016 0.02 0.299 LVEDVI, ml/m2 -0.07 <0.001 -0.02 0.332 LV systolic function LVEF (Simpson's), % -0.04 0.01 -0.16 <0.001 Longitudinal strain, % 0.14 <0.001 0.19 <0.001 LV diastolic function Septal e', cm/sec -0.08 <0.001 -0.02 0.169 E/e' septal 0.04 0.005 -0.02 0.138 LAVI, ml/m2 -0.05 0.003 -0.04 0.026 Conclusion Two non-invasive measures of aortic stiffness, cfPWV and TAC, demonstrate differential associations with LV structure and function in late life. Greater cfPWV is more robustly associated with LV structure and function than TAC.

Arterial Stiffness Is Associated With QTc Interval Prolongation in Patients With Heart Failure

Background: A prolonged corrected QT (QTc) interval is a known risk factor for adverse cardiac events. Understanding the determinants and physiologic correlates of QTc is necessary for selecting proper strategies to reduce the risk of adverse events in high-risk patients. We sought to evaluate the role of arterial stiffness in heart failure as a determinant of QTc prolongation. Method: This was an observational study that recruited ambulatory heart failure patients (New York Heart Association Classes I–II) from an outpatient heart failure clinic. In the supine resting position, consented patients underwent noninvasive 12-lead electrocardiograph (ECG) and hemodynamic monitoring using BioZ Dx impedance cardiography. ECGs were evaluated by a reviewer blinded to clinical data, and QTc interval was automatically computed. Patients with pacing or bundle branch block (BBB) were analyzed separately. Strengths of associations were evaluated using Pearson’s r coefficients and multivariate linear regression. Results: The final sample ( N = 44) was 62 ± 13 years of age and 64% male with ejection fraction of 34% ± 12%. At univariate level, QTc interval moderately ( r > .50) correlated with cardiac output, left cardiac work index, systemic vascular resistance, and total arterial compliance in patients with intrinsically narrow QRS complexes. At the multivariate level, increasing systemic vascular resistance and decreasing total arterial compliance remained independent predictors of widening QTc interval in this group ( R2 = .54). No significant correlations were seen in patients with pacing or BBB. Conclusions: In the absence of conduction abnormalities, magnitude of arterial stiffness, an indirect measure of endothelial dysfunction, is associated with QTc interval prolongation.