cardiac pacemaker

1st2nd3rd
AAI
DDD
VVI
  • 1st letter: chamber pased, atrial, ventricular, dual
  • 2nd letter: sensing, atrial, ventricular, dual
  • 3rd letter: inhibition
    • I: inhibit atrial on ventricular pacing
    • D: lead in A, V. Sensing in A or V. Can pace in A or V. Can inihibit. Can trigger ventricular pacing based on atrium. AV nodal ablation
  • Pacing:
    • atrium: p waves
    • RV: LBBB
    • LV: RBBB
    • AV: physiologic QRS

Indications for pacemaker

Current guidelines recommend implantable cardioverter-defibrillator (ICD) therapy for the primary prevention of sudden cardiac death (SCD) in patients with myocardial infarction (MI) with persistent left ventricular ejection fraction (LVEF) ≤30%, who are at least 40 days post-MI and 3 months post-revascularization (ie, coronary artery bypass grafting or percutaneous coronary intervention, if performed).  It is also recommended in those with LVEF ≤35% and NYHA class II or III symptoms, regardless of prior MI.

This patient's MI was treated with percutaneous revascularization 4 months ago, and he is on optimal medical therapy.  He has persistent left ventricular dysfunction with an ejection fraction of 25%.  The most appropriate next step is to counsel and offer him ICD placement for primary prevention of SCD.