Right ventricular infarction (RVMI ) is a common cardiac emergency in coronary care units. It can be termed as a mechanical complication of infero-posterior STEMI .However , around 10 % of anterior MI do develop this complication . Onset of refractory hypo-tension in spite of correcting hypovolemia suggests RVMI.RVMI generally comes under class 3 (Cidar Siani /Diamond -Forester classification of STEMI ) , ie silent lung with systemic hypotension. (RV shock requires an unique definition , as it can not be included in traditional definition of cardiogenic shock as the PCWP is likely to be normal.
How to manage a full blown RVMI who is not showing signs of improvement ?
Following is an extract from our coronary care unit experience
(do not ask for evidence for everything !)
- Consider immediate angiogram to know the anatomy of the problem .Try opening the RCA which is most likely to be the culprit (Any associated critical LCX /LAD lesion must be attended too ! )If the duration of MI is beyond 36 hours culprit lesion may be left untouched or at least not our primary target !
- Inotropic support (Doubtamine continuous infusion is preferred .Milrinone for the rich !)
- There is no specific RV assist devices available.(LV assist device has no role in RV )
- Restrict fluid (Opposite to RVMI guidelines) There have been instances of overzealous fluid therapy resulting intra-cardiac hypervolemia. IVS encroaching LV worsening the cardiac index .
- Pacing is definitely required in severe bradycardia or CHB . Dual chamber pacing is the ideal choice to maintain AV synchrony as we desperately need the atrial booster pumb for a failing RV . (Please realise , VVI pacemakers , can still save lives as it takes care of extreme bradycardias effectively )
- PCWP in the setting of RVMI is an unreliable parameter of true cardiac function.(In almost 90 % of RVMi some degree of LVMI is present ) . In RVMI PCWP is determined by a delicate balance between LVEDP and the onward stroke volume from a failing RV .) The alter tend to bring the PCWP down former would keep it high . Which component is operating at a given point is a wild guess . The situation get quiet complex in the setting of multiple vaso-active drugs , pacemaker , ventilator
- Balloon Atrial septostomy /dilatation might help ( Hypoxia may worsen as elevated RA mean pressure may shunt right to left however cardiac out put might improve)
- Pericardiotomy or simple splitting of pericardial layers has been tried (Improves RV restriction effect)
- If the patient is on ventilator keep the PEEP well below the standard recommendations (RV will struggle more ! )
- Pacing catheters can irritate the RVMI in their raw zone and trigger recurrent ventricular arrhythmia .( Often labelled wrongly as Ischemic electrical storm !)
- Call Nephrologist consult if renal function deteriorates . Peritoneal dialysis is preferred . It is worthy to know , deaths have occurred on hemo dialysis table.
Final message
RV shock carries a dismal outcome , almost reaching as that of an LV cardiogenic shock. Ironically ,the most important prognosticator in RVMI is the quantum of LV involvement !
Dr.S.Venkatesan MD 