Previously well 64 year male presents to ED with 90 minutes of retrosternal chest pain after riding his bike.
This is his ECG….
- Atrial ~ 60/min.
- Ventricular ~ 36/min
- Rhythm – regular. No P-QRS relationship therefore complete heart block
- Axis ~ +60* (Normal)
- PR – n/a
- QRS ~ 90 msec
- QTc ~ 380 msec
- STE (II, III & aVF) [III > II]
- STD (V2-5, I & aVL)
- V1 isoelectric ST.
- Q-wave in lead III
Inferior STEMI with right ventricular extension (STE III>II, isoelectric ST V1, STD V2) and complete heart block.
His BP drops to 60…
What do you do now ?!?!?
Here is our patient’s ECHO…
Definite RV hypokinesis. No pericardial effusion/tamponade.
Right Ventricular Infarction & Shock
- Right ventricular infarction rarely occurs in isolation.
- Complicates ~ 1/3 – 1/2 of all inferior AMIs.
- RV infarction is a common cause of shock.
- Inferior AMI, clear lung fields & hypotension…
- ~20% of shocked patients in GUSTO-I.
- Carries a similar in-hospital mortality rate to that of LV-infarction & shock !!
- Often complicated by bradydysrhythmias.
Simply put, the infarcting RV fails to offer a sufficient preload to the LV. Consequently reducing cardiac output & resulting in systemic hypoperfusion.
- Volume-sensitive state (in contradistinction from the pressure-sensitive state of LV-infarction).
- Patients are dependent upon preload.
- Classically, high right atrial pressures but low systolic pulmonary artery pressures.
- A disproportionate elevation of RV-filling due to excessive volume loading can result in marked RV dilatation, paradoxically causing high pulmonary-wedge pressures secondary to a left-ward shift of the intraventricular septum.
- This is the physiologic concept of Biventricular Interdependence. – see image below.
- Shock can be compounded by factors that impair RV-filling such as;
- Intravascular volume depletion
- Concomitant atrial infarction
- Loss of AV-synchrony
- Avoid nitrates
- Preload maintenance / Volume replacement
- IV fluid boluses
- Caution: excessive amounts may further compromise RV function.
- Some advocate for placement of pulmonary-artery catheter.
- Suggested target – RAP 10-14mmHg [>14mmHg associated with reduced RV function]
- Oxygen (w/ impaired gas-exchange & respiratory failure)
- Antiplatelet therapy + anticoagulation.
- Aspirin loading
- Clopidogrel / Ticagrelor etc.
- Heparin / Bivalirudin etc.
- Early !!
- ?TPA & other newer agents prevent shock better than streptokinase.
- Thrombolytics become much less effective once shock is established (streptokinase maybe better than TPA in this instance)
- Improved survival (amongst shocked STEMI patients) over those who receive thrombolysis.
- Typically results in successful reperfusion (1-2 vessels involved on average).
- Early revascularisation can result in near immediate recovery of RV function.
- Intra-aortic Balloon Counterpulsation.
- Many text-book references suggest this as a stabilisation manoeuvre for those with shock awaiting PCI.
- Recent data (particular IABP-SHOCK II) suggest that the use of IABP heralds no significant reduction in 30-day mortality nor reduction in 12-month all-cause mortality.
- Dobutamine, noradrenaline, milrinone, levosimendan etc.
- Electrical stabilisation.
- Maintenance of atrioventricular synchrony.
- Transcutaneous or transvenous pacing may be required.
- With the diagnosis made, our Cardiac Cath team was notified & mobilised to the hospital
- IV fluid bolused with temporary improvement in SBP to ~ 90mmHg.
- Atropine trialled without benefit.
- At angiography.
- Heavy thrombosed proximal RCA lesion identified & successfully reperfused.
- Shock persisted despite reperfusion & insertion of temporary pacing wire.
- IABP placed & patient transferred to ICU on inotropes.
- DC to ward on Day 4 of admission.
- DC home well on Day 8 post-infarct.
- Hasdai D et al. Cardiogenic shock complicating acute coronary syndromes. Lancet. 2000 Aug 26;356(9231):749-56.
- Jacobs AK et al. Cardiogenic shock caused by right ventricular infarction: a report from the SHOCK registry. J Am Coll Cardiol. 2003 Apr 16;41(8):1273-9.
- Inohara T et al. The challenges in the management of right ventricular infarction. Eur Heart J Acute Cardiovasc Care. 2013 Sep;2(3):226-34.
- Right Ventricular Myocardial Infarction – UpToDate.com
- Thiele H et al. Intraaortic balloon support for myocardial infarction with cardiogenic shock. N Engl J Med. 2012 Oct 4;367(14):1287-96.
- Thiele H et al. Intra-aortic balloon counterpulsation in acute myocardial infarction complicated by cardiogenic shock (IABP-SHOCK II): final 12 month results of a randomised, open-label trial. Lancet. 2013 Sep 2. pii: S0140-6736(13)61783-3