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This contrasts with the pseudofusion beat wherein the pacemaker impulse does not affect the complex of the natural beat of the heart. Pseudofusion beats are normal. Rare or isolated fusion beats caused by pacemakers are normal as well, but if they occur too frequently may reduce cardiac output and so can require adjustment of the pacemaker. [3]
This phenomenon (an intrinsically slower pacemaker activity being unmasked by failure of faster pacemaker tissue 'upstream') is called an escape rhythm, the lower rhythm having escaped from the dominance of the upper rhythm. As a rule, premature ectopic beats (i.e. with a shorter than the prevailing preceding R-R' interval) indicate increased ...
While the sinoatrial node typically regulates the heartbeat during normal sinus rhythm, PACs occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat, [1] in contrast to escape beats, in which the normal sinoatrial node fails, leaving a non-nodal pacemaker to initiate a late beat.
In the standard non-pacemaker cell the voltage during this phase is more or less constant, at roughly -90 mV. [11] The resting membrane potential results from the flux of ions having flowed into the cell (e.g. sodium and calcium), the flux of ions having flowed out of the cell (e.g. potassium, chloride and bicarbonate), as well as the flux of ...
Wandering atrial pacemaker may be seen in young, healthy individuals as well as in the elderly and those with lung disease. [2] The cause of wandering atrial pacemaker is unclear. Increased tone from the vagus nerve may factor into the rhythm appearing in young, healthy individuals who exercise. The vagus nerve is a part of the parasympathetic ...
Atrial tachycardia is a type of heart rhythm problem in which the heart's electrical impulse comes from an ectopic pacemaker (that is, an abnormally located cardiac pacemaker) in the upper chambers of the heart, rather than from the sinoatrial node, the normal origin of the heart's electrical activity.
If more than two such beats are seen, then the condition is termed junctional rhythm. On the surface ECG , premature junctional contractions will appear as a normally shaped ventricular complex or QRS complex , not preceded by any atrial complex or P wave or preceded by an abnormal P wave with a shorter PR interval .
Pre-excitation may not cause any symptoms but may lead to palpitations caused by abnormal heart rhythms. It is usually diagnosed using an electrocardiogram, but may only be found during an electrophysiological study. [2] The condition may not require any treatment at all, but symptoms can be controlled using medication or catheter ablation.