Transcript Inferior and Rt Vent MI pptx

Inferior/Right Ventricular
Infarction
CLINICAL PRESENTATION AND
TREATMENT
Lady Minto Hospital Emergency Rounds
February 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
 TNK
 Cautious
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 – Pressors
 Norepinephrine
Start 0.03 mcg/kg/min IV
 Dobutamine
Start 2 mcg/kg/min -titrate
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
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
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
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.
Vitals
 BP 90/48
 MAP 62
 HR
55/min
 RR
18
 Sats
95% on room air
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.
What are you going to do?
ECG
X-ray tech is coming, will be about 5 minutes.
Labs
Lab tech is taking labs, will be about 5-10 minutes.
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.