During high-dose vasopressor therapy, which ECG change most reliably indicates supply–demand ischemia due to increased afterload?
ST segment depression
High-dose vasopressor therapy sharply raises systemic vascular resistance and afterload, increasing myocardial oxygen demand. When supply cannot keep up with this increased demand, sub-endocardial ischaemia develops, producing horizontal or down-sloping ST segment depression on the monitored leads — the classical ECG signature of supply–demand (type 2) ischaemia.
QT shortening is seen with digoxin / hypercalcaemia, PR shortening with pre-excitation, and tall P waves with right atrial enlargement — none of these indicate ischaemia.
Hence, ST segment depression.
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Important Questions from Pharmacology
During ECG monitoring, which drug is most likely to cause bradycardia?
Which type of stress test involves the use of medication instead of physical exercise?
Which ECG change most reliably indicates quinidine toxicity?
What is the most appropriate initial management for a patient presenting with symptomatic bradyarrhythmia?
What ECG change might be seen after administration of calcium channel blockers?
