Relationship between Augmentation Index and Wall Thickening Fraction during Hypotension in an Animal Model of Myocardial Ischemia-Reperfusion and Heart Failure.

Aims: Non-invasive indices to evaluate left ventricular changes during ischemic heart failure are needed to quantify the myocardial impairment and the effectiveness of therapeutic manoeuvres. The aims of this work were to calculate the Wall Thickening Fraction (WTF) and the Augmentation Index (AIx) and to assess the relationship between WTF and AIx using data obtained from an animal model with heart failure followed by a myocardial ischemia stage and a reperfusion stage.

Methods: Nine Corriedale sheep that had been monitored for 10 minutes during a basal stage underwent 5-minute myocardial ischemia, followed by 60-minute reperfusion.

Determinants of Ca2+ release restitution: Insights from genetically altered animals and mathematical modeling.

Each heartbeat is followed by a refractory period. Recovery from refractoriness is known as Ca2+ release restitution (CRR), and its alterations are potential triggers of Ca2+ arrhythmias. Although the control of CRR has been associated with SR Ca2+ load and RYR2 Ca2+ sensitivity, the relative role of some of the determinants of CRR remains largely undefined.

Non-β-Blocking Carvedilol Analog, VK-II-86, Prevents Ouabain-Induced Cardiotoxicity.

Background: It has been shown that carvedilol and its non β-blocking analog, VK-II-86, inhibit spontaneous Ca release from the sarcoplasmic reticulum (SR). The aim of this study is to determine whether carvedilol and VK-II-86 suppress ouabain-induced arrhythmogenic Ca waves and apoptosis in cardiac myocytes.

Methods and results: Rat cardiac myocytes were exposed to toxic doses of ouabain (50 µmol/L).

Experimental assessment of a myocyte-based multiscale model of cardiac contractile dysfunction.

Cardiac contractile dysfunction (CD) is a multifactorial syndrome caused by different acute or progressive diseases which hamper assessing the role of the underlying mechanisms characterizing a defined pathological condition. Mathematical modeling can help to understand the processes involved in CD and analyze their relative impact in the overall response. The aim of this study was thus to use a myocyte-based multiscale model of the circulatory system to simulate the effects of halothane, a volatile anesthetic which at high doses elicits significant acute CD both in isolated myocytes and intact animals.

Assessment of Intra-Aortic Counterpulsation in an Animal Model of Heart Failure and Myocardial Ischemia.

The effectiveness of intra-aortic balloon pumping (IABP) is currently evaluated using indirect indexes. The diastolic pressure augmentation is quantified using the subendocardial viability ratio (SEVR) and the DABAC/SABAC index (areas beneath the aortic pressure-time signals during the diastolic and systolic periods, respectively). The SEVR requires invasive recordings of left ventricular pressure; the DABAC/SABAC index may represent an alternative, since it only requires an aortic pressure signal.