CONDUCTION SYSTEM OF THE HEART PDF BASICS SIMULATOR
The Cardiac Safety Simulator (CSS V2.0) platform was used to simulate human left ventricular cardiac myocyte action potential models. Torsade de Pointes (TdP)) in virtual human subjects.Įxperimental Approach: To assess drug proarrhythmic risk, we used a set of in vitro electrophysiological measurements describing ion channel inhibition triggered by the investigated drugs.
Future research is needed to understand the precise molecular and functional changes resulting in these arrhythmias.īackground and Purpose: To determine the predictive performance of in silico models using drug-specific preclinical cardiac electrophysiology data to investigate drug-induced arrhythmia risk (e.g. However, identifying those at risk of developing fascicular arrhythmias is not yet possible. Catheter ablation is an effective therapy in nearly all forms of reentrant arrhythmias involving Purkinje tissue. The variation in functional properties of Purkinje cells in different areas of the His-Purkinje system underlie the propensity for reentry within Purkinje fibres in structurally normal and abnormal hearts. Studies of Purkinje-cell electrophysiology show multiple mechanisms responsible for ventricular arrhythmias, including enhanced automaticity, triggered activity and reentry. Although the histology and physiology of the His-Purkinje system have been studied for more than a century, its role in ventricular arrhythmias has recently been discovered with the ongoing elucidation of the mechanisms leading to both benign and life-threatening arrhythmias. The His-Purkinje system is a network of bundles and fibres comprised of specialised cells that allow for coordinated, synchronous activation of the ventricles. Response can propagate, at least decrementally, in fibers in which the rapid, Na+-dependent upstroke is absent, and can cause reentrant excitation by so doing. The response of depressed fibers may depend on excitatoryĮvents similar to those responsible for the slow component of the cardiac action potential. The response in the depressed segment is graded. A second active depolarization can be evoked by cathodal stimulation during much of the The action potential in the depressed segment (the slow response) differs from the normal action potential In the middle chamber of about 0.05 m/sec, or one-way block, or two-way block with summation of the graded responses in theĭepressed region. Each method of depression resulted in slow and probably decremental conduction with an effective conduction velocity
The depressed segment was in the center chamber of a three-chamber bath the ends of the bundle were exposed to normal Tyrode
CONDUCTION SYSTEM OF THE HEART PDF BASICS PLUS
The excitability of short segments (5–7 mm) of bundles of canine Purkinje fibers was depressed by exposure to 15–18 mM K+, to 15–18 mM K+ plus 5 x 10-6 epinephrine or norepinephrine, to low K+, and to low Na+.
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