PHYS30001 Lecture 21: 21 Hypertrophy and arrhythmia A
Document Summary
Arhythmias / dysrhythmias: abnormalities of electrical rhythm (faster/slower/unstable) Symptoms: palpitations" to critical reduction in cardiac output (e. g. heart block - no output) Altered action potential (ap) generation and/or conduction processes. No fast na channels like in ventricular myocytes. Only one pacemaker cell (the fastest) is required to control heartbeat. Sa node pacemaker overdrives" other pacemakers pacemaker regulation involves: symp (ad & nad) ( i-f, i-ca, i-k) [i=current] increases hr parasymp (ach) ( i-f, i-ca, i-k) decreases hr. Sympathetic effect on latent (ie hidden) pacemaker, takes over the usual pacemaker. Parasympathetic effect on pacemaker allows latent pacemakers to emerge injured node cells develop pacemaker function (ie ischemia), loss of rmp, shows oscillation. Signal comes from node area but is unstable, moves around. Normal nodal automaticity altered: unstable rhythm alternative pacemaker emerges. Triggered activity in the ventricle due to: altered ca ion homeostasis & unstable rmp. 2 types of oscillation: early afterdepolarisation (ead) delayed afterdepolarisation (dad)
