In db/db, a model of HFPEF, selective HR reduction by If-inhibition improved vascular stiffness, LV contractility, and diastolic function. Therefore, If-inhibition might be a therapeutic concept for HFPEF, if confirmed in humans.

Aldosterone causes a substrate for atrial arrhythmias characterized by atrial fibrosis, myocyte hypertrophy, and conduction disturbances. The described model imputes atrial proarrhythmia directly to aldosterone, since ventricular haemodynamics appeared unaltered in this model. This mechanism may have therapeutical impact for primary and secondary prevention of AF.

The Anrep effect represents the alteration of left ventricular (LV) contractility to acutely enhanced afterload in a few seconds, thereby preserving stroke volume (SV) at constant preload. As a result of the missing preload stretch in our model, the Anrep effect differs from the slow force response and has a different mechanism. r The Anrep effect demonstrated two different phases. First, the sudden increased afterload was momentary equilibrated by the enhanced LV contractility as a result of higher power strokes of

Arrhythmogenic right ventricular dysplasia is an important cause of ventricular arrhythmia with a potential risk of sudden cardiac death in a young population. In order to define risk factors of cardiac arrest, angiographic and electrophysiological data from 60 patients with angiographically documented arrhythmogenic right ventricular dysplasia (of whom 20 also had spontaneous non-sustained ventricular arrhythmias, 27 sustained ventricular tachycardia and 13 suffered cardiac arrest with documented ventricular fibrillation before resuscitation) were analysed. There were no statistically significant differences in right ventricular volume, global right ventricular ejection fraction (RVEF), right ventricular structure, mean age at the time of diagnosis and angiographic left ventricular contraction abnormalities in the subgroups of patients with different forms of spontaneous arrhythmias. Only in a subgroup of patients with cardiac arrest and inducible sustained ventricular tachycardia did right ventricular volume (P < 0.05), ejection fraction (P < 0.001) and the amount of structural changes (P < 0.01) reveal significant results. A subgroup of patients with structural alterations and a low level of right ventricular function is at a high risk of cardiac arrest, although strenuous exercise and sport remain most important risk factors.

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