Dual chamber pacemaker – Chest X-ray
Dual chamber pacemakers are able to provide multiple modalities of pacing. The atrial lead senses the atrial electrogram if present and triggers the ventricular channel after the programmed atrioventricular delay. In this way they can provide atrioventricular sequential pacing which is also known as physiological pacing. Though it is called physiological pacing, since the ventricular pacing is from the right ventricular apex, the signal flow does not follow the exact pattern as in the normal atrioventricular conduction system. Long term right ventricular apical pacing is known to produce left ventricular dysfunction and heart failure due to dyssynchrony of left ventricular contractions [1]. That is why right ventricular pacing is being taken over by other modalities like cardiac resynchronization therapy and His bundle pacing, which reduces the chance of dyssynchrony and left ventricular dysfunction in the long run.
Reference
- Didier Klug, Stephane Boule, Ludivine Wissocque, David Montaigne, Xavier Marechal, Sidi Mohamed Hassoun, Remi Neviere. Right Ventricular Pacing With Mechanical Dyssynchrony Causes Apoptosis Interruptus and Calcium Mishandling. Can J Cardiol. 2013 Apr;29(4):510-8.