How to manage refractory RV shock with infero-posterior MI ?
Posted Jan 27 2013 3:36am
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 untouchedor at least not our primary target !
Inotropic support (Doubtamine continuous infusion is preferred .Milrinone for the rich !)
There is no specific RV assist devicesavailable.(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 dialysisis preferred . It is worthy to know , deaths have occurred on hemo dialysis table.
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 !