Investigation of the optimal rabbit model for aortic valve stenosis

Background/Purpose

Anatomically, hemodynamically relevant and validated animal models for aortic valve stenosis are of great need. Drolet rabbit model with tricuspid anatomy produced conflicting results for unclear reasons. We hypothesized that limitations concentrate in the regimen administration. We sought to evaluate multiple doses, ways of administration and time periods.

Methods

We included New Zealand rabbits in 4 groups: Group A (Drolet): was fed with normal chaw (nc)+0.5% cholesterol (chol)+3500 IUs Vitamin D2/kg (VD2, ergocalciferol, Sigma) in water daily for 12 weeks (wks), Group B: nc+0.5%chol+3500 IUs/kg VD2 in oil incorporated in a bisquit daily for 8 wks, Group C: nc+0.5%chol+8750 IUs/kg VD2 in oil-biscuit for 8 wks, Group D: nc+0.5%chol+17500 IUs VD2 in oil-biscuit for 8 wks vs controls (fed only with nc). After 12 and 8 wks the rabbits were sacrificed. Aortic valve area (AVA) and mean gradient (meanGr) were assessed with echocardiography (Vivid 7, M3S transducer, GE) and serum obtained, at baseline and before sacrifice. VD2 levels were evaluated through Chemiluminescent Microparticle Immuno Assay (CMIA, Abbott) and liquid chromatography – tandem mass spectrometry (LC-APCI-MS/MS). Animals received i.v. 18F-NaF one hour before sacrifice and valve was ex-vivo imaged with microPET/CT (Mediso nanoScan). Aortic cusps were analyzed with Fourier-Transformed Infrared Spectroscopy (FT-IR, Nicolet 6700 spectrometer, OMNIC 7.3 software). Valves from surgical patients with severe stenosis served for comparison purposes.

Results

In Group A at 12 wks AVA and meanGr remained unchanged but biomineralization was detected with FT-IR with vibrations in the region of 1800–800 cm–1 demonstrating the deposition of CaCO3 and non-hydroxyapatite Ca3(PO4)2 identical to human lesion. Calcification was detected on cusps with 18F-NaF. VD2 levels were out of upper detection range with CMIA due to cross reaction, whereas all samples measured through LC-MS/MS were below the detection limit of the method (<19,1 ng/mL). Significant Assessment heterogeneity (RSD=27%) was observed on VD2 water regimen. In Group B, AVA changed from 0.5 cm2 to 0.4 cm2 and meanGr increased from 1.1 to 2.1 mmHg, p<0.05 and in Group C AVA: 0.5 cm2 to 0.3 cm2 and meanGr: 1 to 2.95 mmHg, p<0.05, while VD2 serum concentration were 511 ng/mL. In Group D animals die unexpectedly at 2 weeks, with autopsy revealing massive myocardial hypertrophy of the left ventricle (LVH) without compromise of the aortic valve.

Conclusions

The modified diet produces aortic valve stenosis and biomineralization detectable with 18F-NaF, chemically identical to human lesion. Very high doses of Vitamin D2 directly produce LVH, possibly leading to arrythmiogenesis. The modified high-fat-vitamin D2 rabbit model proved suitable for translational research of aortic valve stenosis disease.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): National and Kapodistrian University of Athens

P3450Aortic stiffness is significantly associated with left ventricular mass in females but not in males: insights from the CORINTHIA study

Introduction

Arterial stiffening may contribute to the increase of left ventricular mass (LVM) and the development of left ventricular hypertrophy (LVH). Although male gender has been also found to be an independent determinant of LVH, it is unknown if the adverse effect of increased aortic stiffening on LVM differs between males and females.

Aim

To evaluate the association of aortic stiffness as assessed by carotid-to-femoral pulse wave velocity (cf-PWV) with LVM and LVH in a general population and compare these associations between males and females.

Methods

Demographic, laboratory and clinical data of 1686 subjects (693 males and 993 females) from the cross-sectional, observational study “Corinthia” were analyzed. All subjects underwent applanation tonometry and pulse wave analysis for the measurement of cf-PWV and echocardiography examination for the computation of LVM which was adjusted by body surface area providing the LVM index (LVMI). Multivariate linear regression analysis was performed for the determination of independent factors related with LVMI. Receiver operator curve analysis (ROC) was used to compare the ability of cf-PWV to predict LVH, in males and females separately.

Results

In the female population, significant and independent determinants of LVMI were: age (beta=0.243, p<0.001), urea (beta=0.119, p=0.001), hypertension (beta=0.089, p=0.028) and cf-PWV (beta=0.096, p=0.021). In contrast, in the male population, LVMI was independently related with age (beta=0.242, p<0.001), systolic blood pressure (beta=0.095, p=0.027), LDL (beta=-0.087, p=0.047) and creatinine (beta=0.092, p=0.031). ROC analysis showed that cf-PWV is a stronger predictor of LVH in females than in males (figure).

Conclusion

Increased aortic stiffness measured by cf-PWV is significantly related with increased LVMI regardless from age and other risk factors only in females. Moreover cf-PWV was a stronger predictor of left-ventricular hypertrophy in females than males. These findings should be further explored in prospective studies.

P5312Sleep duration and carotid atheromatic burden. Insights from the Corinthia study

Background

Sleep is an essential physiological process and disturbance of sleeping pattern may be associated with cardiovascular risk profile and atheromatosis. Short but also long sleep duration (LSD) may be adversely affect cardiovascular parameters.

Purpose

To study how sleep duration is associated with cardiovascular risk profile and carotid atherosclerotic burden.

Methods

Corinthia study is a cross sectional epidemiological study based on 2043 inhabitants (age 40–99 years) of Corinthia region in Greece. Ultrasonography was used to measure intima media thickness (IMT) in the left and right common carotid artery, carotid bulb and internal carotid artery. The mean IMT (meanIMT) were determined as representative values of carotid atherosclerosis burden. Thickness of IMT>1.5 mm or protrusion >50% compared to adjacent segments was considered as atherosclerotic plaque. Based on questionnaires of Corinthia study, total sleeping time per day was recorded. A sleep duration of 7 to 8 h was consider normal (NSD), sleep duration <6 h was consider very short (VSSD), 6–7 h sleep duration was considered short (SSD) and participants with >8 h sleep duration was categorized as LSD.

Results

Concerning gender more men than women were categorized in the NSD (26% vs. 21%, p<0.001). Subjects in the NSD were also younger compared to subjects categorized in other sleeping patterns (VSSD: 66±12 y vs. SSD: 63±12 y vs. NSD: 62±12 y vs. LSD: 66±12 y, p<0.001), have less prevalence of diabetes mellitus (p<0.05). There was no difference according to sleeping pattern in body mass index, prevalence of hypertension, cardiovascular disease, hyperlipidemia and on current smoking habits according to sleeping patterns. Interestingly, meanIMT (VSSD: 1.08±0.51 mm vs. SSD: 0.97±0.42 mm vs. NSD: 0.97±0.41 mm vs. LSD: 1.14±1.64 mm, p=0.04) and carotid atherosclerotic plaque (VSSD: 35% vs. SSD: 25% vs. NSD: 20% vs. LSD: 30%, p=0.006) was decreased in NSD subjects. Importantly, even after adjustment for the confounders logistic regression analysis revealed that subjects in the NSD group have 50% less odds of carotid atheromatic plaque than subjects in the VSSD (Odds ratio: 0.5, 95% CI 0.28–0.90, p=0.02) (Figure).

Conclusion

A balanced sleeping pattern with 8h of sleep daily can act as an additive cardioprotective factor in the modern western type societies. Short especially less than 6 hours and long (>8 hours) sleeping duration may act as a cardiovascular risk factor.

P4392A systematic review and meta-analysis of the cardiovascular effects of e-cigarette

Background

Electronic cigarette (EC) is marketed as a safe alternative to tobacco smoking, but EC cardiovascular effects remains largely unknown.

Purpose

To systematically review and meta-analyse published literature to investigate the cardiovascular effects and associated risk from EC use.

Methods

We searched PubMed from January 2000 until November 2017 for published studies assessing the cardiovascular effects of EC. For each eligible study we used the mean difference (MD) with 95% confidence intervals (CIs) for SBP, DBP and HR. The pooled MDs for each outcome of interest were calculated by using a fixed effects model. The presence of heterogeneity among studies was evaluated by the I2 statistic.

Results

We report conflicting evidence on the effects of EC on heart rate and blood pressure, which is mainly based on non-randomized clinical studies of moderate quality. In a meta-analysis of 14 studies (n=441 participants), that despite the negative effects of EC on heart rate (pooled MD=2.27, 95% CI: 1.64 to 2.89, p<0.001), diastolic (DBP, pooled MD=2.01mmHg, 95% CI: 0.62 to 3.39, p=0.004) and systolic blood pressure (SBP, pooled MD=2.02mmHg, 95% CI: 0.07 to 3.97, p=0.042), benefits may be observed in terms of blood pressure regulation when switching from tobacco smoking to EC (SBP pooled MD=−7.00, 95% CI: −9.63 to −4.37, p<0.001; DBP pooled MD=−3.65, 95% CI: −5.71 to −1.59, p=0.001). Evidence suggests that EC negatively affects endothelial function, arterial stiffness and the long-term risk for coronary events, but these findings are derived from single study reports and have not been confirmed in additional studies.

Conclusions

We report adverse effects of EC use on heart rate and blood pressure. Unless supported by stronger evidence, EC should not be labelled as cardiovascular safe products. Future studies should delineate whether EC use is less hazardous to cardiovascular health than conventional cigarette smoking.