An Interesting ECG Case

71 F with sudden onset 10/10 chest pain and nausea. Calls 911. EMS does this ECG. Blood pressure 90/60 mmHg, heart rate 51 BPM. Taken directly to cath lab.

Inferior STEMI

Junctional bradycardia, 51 BPM, no P waves evident.

QT 680 ms and QTc 627 ms

ST elevation II, III and aVF, ST depression T inversion I, aVL V2-5

In cath lab an occluded RCA was found and opened with PCI/stenting.

Inferior myocardial infarctions often cause bradycardia & hypotension due to direct ischemia of conduction system (supplied by RCA) and the Bezold-Jarisch reflex. This reflex is triggered by ischemia & stretch of the inferoposterior myocardium stimulating vagal afferents, leading to increased parasympathetic tone, vasodilation, & slowed heart rate. Bradyarrhythmias occur in roughly 15–30% of patients with inferior MI.

As always, prompt recognition is essential to initiate urgent reperfusion—via primary PCI or fibrinolytic therapy—to limit myocardial damage.

Management of bradycardia and hypotension includes:

·       Atropine: First-line for bradycardia; administer 0.5 mg IV, repeat every 3–5 minutes as needed, up to 3 mg total.

·       Intravenous Fluids: A 250–500 mL bolus of isotonic saline is typically used to support blood pressure. Ringer’s lactate is a good alternative providing more balanced fluid.

·       Temporary Pacing: Consider if bradycardia & hypotension persist despite medical therapy.

Nitroglycerin is often avoided in inferior infarct. In hypertensive patients with inferior infarction it can be used cautiously for pain relief and coronary dilation.