BACKGROUND In patients with mechanical aortic and mitral valves and left ventricular tachycardia, catheter ablation may be prevented by limited access to the left ventricle. METHODS AND RESULTS In our series of 6 patients, 2 patients underwent direct surgical ablation and 4 underwent epicardial catheter ablation via a pericardial window. All patients had abnormal low voltage areas with fracti...

The effect of increased coronary flow on transmural ventricular repolarization was investigated in six pentobabital-anesthetized sheep. Fresh blood at 10 ml/min was injected into the left circumflex coronary artery (LCX) in addition to the normal coronary flow. Unipolar electrocardiograms were simultaneously registered from epicardium, mid-myocardium and endocardium with fine plunge needles. Ac...

Mechanism for ST Depression. Introduction: A mechanism is proposed for ST depression that arises on the epicardial surface above the border between normal and ischemic tissue. Depression is caused by current that flows in a transmural loop that begins and ends at the lateral boundary between healthy and ischemic tissue and that passes through the transmural boundary between healthy and ischemic...

iiAcknowledgements -ivList of Figures -viAbbreviations -viiEpigraph -1Chapter 1. Background -21.1 The Epicardial Border Zone and Arrhythmogenesis Post-Infarction -21.2 Computational models and the study of cardiac arrhythmias -61.3 Electrophysiological and Structural Determinants of Arrhythmia -71.4 Objectives -9Chapter 2. Action Potential Rate Dependence in a Computational Model of Canine Epic...

We studied 13 anesthetized dogs in which a third heart sound (S3) was repeatedly induced by hypoxemia plus fluid overload. A miniature accelerometer with a mass of about 1.1 g was applied at three levels--intact chest wall over cardiac apex, in the pericardium and on the epicardium--to record motion of the structures under observation as well as sound. Intraventricular pressure and sound were m...

AIMS The strategies that control formation of the ventricular wall during heart development are not well understood. In previous studies, we documented IGF2 as a major mitogenic signal that controls ventricular cardiomyocyte proliferation and chamber wall expansion. Our objective in this study was to define the tissue source of IGF2 in heart development and the upstream pathways that control it...

This paper describes the development and preliminary testing of a robotic device to facilitate minimally invasive beating-heart intrapericardial interventions. We propose the concept of a subxiphoid-inserted mobile robot (HeartLander) with the ability to adhere to the epicardium, navigate to any location, and administer therapy under physician control. As compared to current laparoscopic cardia...

Application of 25 to 100 /xg of acetylstrophanthidin to the epicardium of the left ventricle of anesthetized and unanesthetized dogs caused hypotension and bradycardia without signs of discomfort. The response developed after an average latency of 8 seconds and lasted up to 12 minutes. Cooling the cervical vagi to 8 to 10°C or prior application of 0.1% procaine hydrochloride to the epicardium o...

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is well-established in patients reduced left ventricular ejection fraction (LVEF), heart failure and wide QRS or indication for pacing. BVP achieves CRT through non-physiological fusion of paced wave-fronts from the RV endocardium LV epicardium. Conduction system utilizing bundle branch area has recently shown to be a safe ...

Forming the early heart The is first organ to form during development and critical for survival of embryo. precise molecular identities various cell types that make up these stages remain poorly defined. Tyser et al. used a combination transcriptomic, imaging, genetic lineage–labeling approaches profile identity locations cells involved in formation mouse embryonic heart. This approach allowed ...