inferior/right ventricular infarction clinical presentation and treatment lady minto hospital...
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Inferior/Right Ventricular Infarction
CLINICAL PRESENTATION AND TREATMENT
Lady Minto Hospital Emergency RoundsFebruary 2015
Prepared by Shane Barclay
Occurrence
Isolated Right Ventricular Myocardial Infarction (RVMI) is rare. More commonly occurs with inferior wall MI, occurring in 30-50 % of
such cases. Approximately 50% patients with RVMI have profound hemodynamic
and electrical complications. However long term outcomes are usually very good.
Clinical Presentation
RVMI: suspect in Inferior MI when patient presents also with:
1. Hypotension
2. Bradycardia
3. JVD
4. Clear chest sounds (no edema)
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.
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.
Hemodynamic consequences of RVMI
Rt. Ventricular output may further be compromised by:
1. Hypoxemia from pulmonary edema
2. Alpha-adrenergic agonists
3. Mechanical ventilation with PEEP
Electrical Consequences – Inferior/RVMI
Bradycardia:
can arise from SA and AV node dysfunction Tachycardia and Ventricular Fibrillation
occur in up to 30% of patients
Treatment
Usual STEMI protocol, ie ASA, IVs, monitor TNKCautious use of Nitrates, beta blockers, diuretics,
opioids and bladder catheterization as these may impact preload, heart rate and contractility.
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
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: 20-25 mcg IV aliquots
Treatment – Analgesics
Dose: mcg/hr
Rate: ml/hr
25 2.5
50 5
75 7.5
100 10
125 12.5
150 15
… …
Fentanyl Infusion:Admixture: Withdraw 20 ml from 100 ml minibag. Add 20 ml (1000 mcg) FentanylTotal Volume 100 ml.
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
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 0.03mcg/kg/min If still hypotensive, consider adding Dobutamine Start 2 mcg/kg/min Fentanyl for pain – 25 mcg and consider infusion.
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.
Exam
Appears in acute distress, moaning and clutching his chest (i.e. real ‘man pain’.
Can answer questions and seems orientedHeart sounds are normalChest is clearJVD just under the ear lobe.
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.