Hypotension After Nitroglycerin: Inferior STEMI With a Failing Right Ventricle
A 58-year-old man arrives 90 minutes after the onset of crushing substernal chest pain. ECG shows 2 mm ST elevation in leads II, III and aVF, with the elevation in III exceeding that in II, plus 1 mm reciprocal depression in I and aVL. Blood pressure is 84/52 mmHg, heart rate is 48 beats/min and regular, JVP is elevated at 12 cm H2O, and the lungs are clear with no crackles. He is warm, alert and mentating normally. In the laboratory the mid right coronary artery is 100% occluded with TIMI 0 flow. En route, EMS gave 0.4 mg sublingual nitroglycerin, after which his systolic pressure fell from 104 to 84 mmHg. The interventionalist asks you to interpret the findings before the wire crosses.
1. Which ventricle is ischemic, and how do the pressure, JVP and lung findings fit together into one explanation?
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The pattern is a proximal-to-mid RCA occlusion taking out the right ventricular marginal branches, so the RV, not just the inferior LV wall, is ischemic.
Reasoning chain:
- ST elevation in III > II with reciprocal depression in I and aVL points to the RCA rather than the circumflex.
- A failing RV cannot eject against pulmonary pressures, so JVP rises (12 cm H2O).
- The same failure means the RV delivers little blood to the LV, so LV preload and stroke volume fall and the patient becomes hypotensive (84/52).
- The LV itself is not congested, so the lungs stay clear.
The discriminating feature is the combination of hypotension + elevated JVP + clear lungs. Hypotension with clear lungs but a flat JVP would suggest hypovolemia or a vagal reaction instead. A right-sided lead (V4R) would confirm RV infarction, and ST depression in V1-V3 may also reflect posterior extension. Bradycardia here is consistent with AV nodal branch ischemia.
2. Was the sublingual nitroglycerin harmful? Explain the physiology and state your immediate management.
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Yes - the 20 mmHg systolic drop is the expected consequence, not a coincidence.
Mechanism: nitrates are venodilators. They reduce venous return, which is exactly the preload the infarcted RV depends on to fill and generate forward flow. In a preload-dependent RV, a fall in filling pressure produces a disproportionate fall in cardiac output and blood pressure. The same logic makes diuretics and other venodilators hazardous in this setting.
Immediate management:
- No further nitrates of any route; document the reaction.
- Lay the patient flat with passive leg elevation.
- Give a cautious crystalloid bolus (about 250-500 mL, reassessing after each bolus) - the standard response to RV infarct hypotension.
- Treat bradycardia if it is contributing (atropine); have transcutaneous and temporary pacing available because the AV node is supplied by the RCA.
- If pressure does not respond to volume, add an inotope/vasopressor rather than more fluid.
- Definitive therapy is reperfusion of the RCA, which frequently restores RV function within hours to days.
3. What monitoring and intraprocedural safeguards would you build into this PCI, and what events would make you pause?
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Because RV function and AV nodal conduction are both at risk, the case should be run as a hemodynamically fragile PCI:
- Continuous invasive arterial pressure (not cuff cycling) so a falling preload or a vagal response is seen immediately.
- Pacing capability on the field before the wire crosses, given HR 48 in an inferior infarct.
- Withhold nitrates, and warn anyone giving sublingual or intracoronary nitroglycerin for spasm.
- Limit contrast volume: a dilated, failing right heart tolerates a large contrast load poorly.
- Watch for bradycardia and hypotension during RCA injections (Bezold-Jarisch reflex) and during sheath removal; treat by stopping the injection, volume, and atropine if needed.
Pause and reassess if: systolic pressure cannot be held above roughly 90 mmHg with volume and low-dose pressor support, if the rhythm deteriorates to high-grade AV block, or if the patient becomes confused or oliguric - those signal that the RV cannot be supported medically and mechanical support or an accelerated reperfusion strategy should be discussed.