RVMI

What is it?

In addition to supplying blood to the RV, the RCA also supplies 25% to 35% of the LV myocardium, and to both the sinoatrial (SA) node and atrioventricular (AV) node.

Depending on where in the RCA the blockage is, both ventricles can be affected and there is potential for bradycardia and heart blocks.

Beta Blockers

Beta blockers should be used with caution for a patient with RVMI, because they decrease heart rate and slow conduction through the AV Node. These patients are already at risk for bradycardia and AV block, and beta blockers can exacerbate both of these.

NTG

For a patient with RVMI, NTG should be given with great caution, if at all. A significant reduction in preload will significantly impair the RV stroke volume, as the infarcted RV cannot compensate. The resulting decrease in RV output means limited LV preload, and decreased LV output.

Pacing

Common dysrhythmias seen with RVMI include sinus bradycardia, atrial fibrillation, and AV block, which may require temporary pacing. Maintaining AV synchrony optimizes ventricular filling and output, so dual chamber pacing may be needed. AV blocks with wide QRSs are due to damage below the AV node and do not respond to atropine, which is the usual first treatment for symptomatic bradycardia.

Reperfusion Therapy

Reperfusion therapy should be initiated at the earliest signs of RV dysfunction. Complete recovery over a period of weeks to months is a rule in a majority of patients, suggesting RV “stunning” rather than irreversible necrosis has occurred.

Symptoms
  • Unexplained hypotension
    • This tells you that the LV output is reduced although this is in part due to HB.
  • JVD
    • DVD tells us that there is plenty of RV preload, so the problem must be in moving the RV preload to the lungs, and to the left side of the heart.
  • Clear lungs
    • Clear lungs indicate that this is not due to LV dysfunction, but instead is a problem with preload to the LV.
  • Pulsus paradoxus
  • Hypoxia
    • decreased blood flow to the lungs leads to less oxygen availability to the tissue. brought on by a decreased preload.
  • Decreased LV preload
    • Decreased preload leads to decreased CO, which can lead to shock, and can be fatal.
Treatment
  • Volume loading
    • Improve preload
  • Pacing
    • Treat HB, and bradycardia
  • Contractility
    • Consider inotropic support with dobutamine to further augment RV output.
  • AVOID:
    • Nitrates, diuretics, and vasodilators, all of which can decrease preload and could extend the MI, causing irreversible damage.