This section deals with the act of forcibly taking control of somebody's cardiac conduction system.

Indications for pacing

  • Asystole or recurrent long sinus pauses
  • Prolonged atrioventricular delay
  • Prolonged QT interval (to prevent torsades de pointes)
  • Hemodynamically unstable bradycardia
  • Bifascicular block(or trifascicular)
  • Mobitz type 2 second degree heart block
  • Recalcitrant VT (for overdrive pacing)
  • Atrial flutter
  • Reentrant SVT
  • Atrial fibrillation or junctional rhythm in diastolic failure
  • Hypertrophic obstructive cardiomyopathy

Contraindications for pacing

  • These are all relative. Sometimes, one may wish to commence pacing in the face of these contraindications, because the benefits outweigh the risk. Frequently, of course, external pacing is still an option.
  • Excessive risk of bleeding due to vascular access
  • Ongoing bacteraemia (the leads may get infected)
  • Hemodynamically stable bradycardia (i.e. do you really need to pace them?)
  • Large areas of  right ventricular infarction (what tissue will you activate among all that dead myocardium?)
  • Intracardiac thrombus:One might dislodge this either by stimulating the chamber, or by the very act of inserting transvenous pacing lines.

Complications of pacing

  • Failure to pace, eg. dislodged leads
  • Asynchrony of the chambers (mainly with VVI mode)
  • Vascular access complications, eg. hematoma, pneumothorax etc.
  • Cardiac chamber access problems, eg. knotting in the chamber, or damage to the tricuspid valve
  • Cardiac chamber damage and potential for cardiac tamponade
  • Lead thrombosis and pulmonary embolism
  • Lead infection and infective endocarditis
  • Arrhythmias, eg. VF, VT (due to the leads irritating the tissue)
  • Inadvertent induction of nasty arrhythmia by the pacing itself
  • "Endless loop" reentrant tachycardia
  • Stimulation of the diaphragm and interference with ventilation

References