RESUMO
Background: Arrhythmic mitral valve prolapse syndrome (ARMV) is a recognized but underdiagnosed disease pattern. Risk factors for ARMV are established but not very well known, and the association of the structural abnormality with ventricular arrhythmias is incompletely understood. Case summary: Here, we present the case of a young man who presented at our hospital for radiofrequency catheter ablation and mitral valve surgery after two episodes of survived sudden cardiac arrest. We discuss the diagnostic and therapeutic strategies that were used. We shine light on the risk factors for ARMV and why early identification is crucial. We address the topic of primary prevention and its limitations. Finally, we discuss different treatment modalities for patients with ARMV. Discussion: More awareness for ARMV is crucial. A consensus statement on clinical management exists, but scientific gaps in prospective data for primary prevention need to be filled and there is a need for a better understanding of the pathogenesis of ARMV.
RESUMO
Voltage-gated Ca(2+) channels regulate cardiac automaticity, rhythmicity and excitation-contraction coupling. Whereas L-type (Cav 1·2, Cav 1·3) and T-type (Cav 3·1, Cav 3·2) channels are widely accepted for their functional relevance in the heart, the role of Cav 2·3 Ca(2+) channels expressing R-type currents remains to be elucidated. We have investigated heart rate dynamics in control and Cav 2·3-deficient mice using implantable electrocardiogram radiotelemetry and pharmacological injection experiments. Autonomic block revealed that the intrinsic heart rate does not differ between both genotypes. Systemic administration of isoproterenol resulted in a significant reduction in interbeat interval in both genotypes. It remained unaffected after administering propranolol in Cav 2·3(-|-) mice. Heart rate from isolated hearts as well as atrioventricular conduction for both genotypes differed significantly. Additionally, we identified and analysed the developmental expression of two splice variants, i.e. Cav 2·3c and Cav 2·3e. Using patch clamp technology, R-type currents could be detected in isolated prenatal cardiomyocytes and be related to R-type Ca(2+) channels. Our results indicate that on the systemic level, the pharmacologically inducible heart rate range and heart rate reserve are impaired in Cav 2·3 (-|-) mice. In addition, experiments on Langendorff perfused hearts elucidate differences in basic properties between both genotypes. Thus, Cav 2·3 does not only contribute to the cardiac autonomous nervous system but also to intrinsic rhythm propagation.