The intra-aortic balloon pump is used as adjunctive therapy in acute MI in several groups of patients:
Patients whose conditions are hemodynamically unstable and in whom circulatory support is required to perform cardiac catheterization and assessment of potentially correctable lesions.
Patients with cardiogenic shock unresponsive to medical therapy, including those who develop mechanical complications (i.e., ventricular septal rupture or papillary muscle rupture).
Patients with persistent ischemic pain despite all medical therapy, including beta and calcium channel blockers, nitrates, full anticoagulation, and oxygen.
Does temporary pacing improve survival in patients with conduction disturbances in MI?
Patients who develop significant conduction disturbances in acute MI usually have increased morbidity and mortality, mainly because this conduction defect occurs in larger Mis regardless of the coronary artery occluded. Temporary pacing will not improve prognosis in these patients despite the resumption of a physiologic heart rate, since the extent of the myocardial damage is directly related to mortality.
What are the indications for temporary and permanent pacing post-MI?
Temporary pacing is recommended in patients with MI who have high-grade atrioventricular (AV) block (second or third degree) or are at risk of developing these conduction disturbances. Indications include:
Second-degree Mobitz II block
Second-degree Mobitz I block and hemodynamic instability
Third-degree heart block
New left bundle branch block
New right bundle branch block with either left anterior or left posterior hemiblock
Pacing is rarely necessary with inferior MI unless associated with hemodynamic instability. The indications for permanent pacing post-MI remain controversial; the aim of this therapy
is to prevent sudden death, but not all sudden deaths are due to high-grade AV block. Also, the timing for implantation of a permanent pacemaker is debatable. Indications for permanent pacing include:
Persistent advanced AV block (usually 7-10 days duration), located at either the AV node or His-Purkinje system
Transient advanced AV block in association with bundle branch block
Paroxysmal AV block