1. Inferior/Right Ventricular Infarction
Clinical Presentation and Treatment
Prepared by Shane Barclay MD

2. Rt. Ventricular MI
Isolated Right Ventricular Myocardial Infarction (RVMI) is rare.
More commonly occurs with inferior wall MI, occurring in % of such cases.
Approximately 50% patients with RVMI have profound hemodynamic and electrical complications.
However long term outcomes are usually very good.

3. Clinical Presentation
RVMI: suspect in Inferior MI when patient presents also with:
Hypotension
Bradycardia
JVD
Clear chest sounds (no edema)

4. Right versus Left Ventricle
Oxygen demand is significantly lower in the Rt Ventricle because of smaller mass and lower afterload
Coronary perfusion in the Rt occurs in both systole and diastole
There is more extensive collateral circulation from left to right coronary arteries.
SA and AV node are supplied by arteries that also supply the Right Ventricle.

5. Hemodynamic consequences of RVMI
Right ventricular failure may cause limited filling pressures in the Rt Ventricle from decreased cardiac output, bi-ventricular failure or both.
Increasing Right Ventricular filling pressures (via fluid infusion) may cause shifting of the septum into the left ventricle which then impairs left ventricular filling and function.

6. Hemodynamic consequences of RVMI
Rt. Ventricular output may further be compromised by:
Hypoxemia from pulmonary edema
Alpha-adrenergic agonists
Mechanical ventilation with PEEP

7. Electrical Consequences – Inferior/RVMI
Bradycardia:
can arise from SA and AV node dysfunction
Tachycardia and Ventricular Fibrillation
occur in up to 30% of patients

8. Treatment Usual STEMI protocol, ie ASA, IVs, monitor TNK
Cautious use of Nitrates, beta blockers, diuretics, opioids and bladder catheterization as these may impact preload, heart rate and contractility.

9. Treatment
If evidence of significant RV dysfunction or cardiogenic shock 1. IV fluid boluses, but try to limit to maximum 1 liter N/S
If still hypotensive/cardiogenic shock after one liter N/S
2. Pressors – Norepinephrine, Dobutamine

10. Treatment – Pressors Norepinephrine Start 0.1 mcg/kg/min IV Dobutamine
Start 2 mcg/kg/min -titrate

11. Treatment – Analgesics
Fentanyl – Usually has minimal or no effect on BP and cardiac output. May have some negative chronotropic effect (decrease HR) which if necessary can be treated with atropine.
Dose: mcg IV aliquots

12. Treatment – Analgesics
Fentanyl Infusion:
Admixture:
Withdraw 20 ml from 100 ml minibag. Add 20 ml (1000 mcg) Fentanyl
Total Volume 100 ml.
Dose: mcg/hr
Rate: ml/hr 25
2.5 50 5 75
7.5
100 10
125
12.5
150 15 …
Start by giving 25 mcg IV bolus and start infusion at 25 mcg/hr.
If no response after 15 minutes repeat bolus and titrate up infusion rate

13. Treatment Summary Inferior MI
IVs, monitor, labs, ECG, CXR
15 lead ECG
TNK if not contraindicated
Have patient on Lifepak and have amp of Atropine handy
If hypotensive, give small fluid boluses to maximum 1 liter
If still hypotensive, consider norepinephrine drip – Start 0.03mcg/kg/min
If still hypotensive, consider adding Dobutamine Start 2 mcg/kg/min
Fentanyl for pain – 25 mcg and consider infusion.

14. Clinical Scenario

15. Clinical Scenario
54 year old male, previously completely healthy, presents with a history of waking with epigastric pain and burping. This increased in severity and is now “10/10” pain.

17. Vitals
BP 90/48
MAP 62
HR 55/min
RR 18
Sats 95% on room air

18. Exam
Appears in acute distress, moaning and clutching his chest (i.e. real ‘man pain’.
Can answer questions and seems oriented
Heart sounds are normal
Chest is clear
JVD just under the ear lobe.

19. What are you going to do?

20. ECG
X-ray tech is coming, will be about 5 minutes.

21. Labs
Lab tech is taking labs, will be about 5-10 minutes.

24. Treatment Summary Inferior MI
IVs, monitor, labs, ECG
15 lead ECG
TNK
Have patient on Lifepak and have amp of Atropine handy
If hypotensive, give small fluid boluses to maximum 1 liter
If still hypotensive, consider Norepinephrine drip – start 5-8 mcg/min
If still hypotensive, consider adding Dobutamine Start 2 mcg/kg/min
Fentanyl for pain – 25 mcg and consider infusion.