Hemodynamic effects of prophylactic amiodarone assessed by pressure–volume analysis in anesthetized female pigs in sinus rhythm—An exploratory study

BACKGROUND: Intravenous amiodarone is used for acute management of severe arrhythmias and can cause hypotension. However, amiodarone's direct hemodynamic and myocardial effects during sinus rhythm are not well characterized. METHODS: Twenty-five anesthetized female pigs (75-80 kg) received a 300 mg intravenous bolus amiodarone over 30 minutes. To assess hemodynamic effects, animals were instrumented with a left ventricular conductance catheter, a pulmonary artery catheter, a carotid artery Doppler flow probe, and a renal vein catheter. Data were recorded at baseline, after 15 and 30 minutes and presented as median with interquartile ranges. RESULTS: Amiodarone reduced systolic and mean arterial blood pressure by 12% (p < 0.001) after 30 minutes infusion, primarily driven by 24% reduction in cardiac output due to combined deceased heart rate (87 (79; 99) beats per minute (bpm) to 72 (62; 81) bpm, p < 0.001) and stroke volume (69 (64; 79) mL to 64 (48; 73) mL, p = 0.004). End-systolic elastance (EES) decreased (0.54 (0.33; 0.63) mmHg/mL to 0.43 (0.29; 0.51) mmHg/mL, p < 0.001), while systemic vascular resistance and arterial elastance (EA) remained unchanged, resulting in an increased EA/EES ratio from 2.45 (2.01;3.53) to 3.26 (2.55; 4.30) (p < 0.001). This impaired cardiac function led to reduced carotid artery blood flow and renal perfusion pressure. CONCLUSION: Infusion of 300 mg amiodarone intravenously in anesthetized pigs in sinus rhythm impaired left ventricular contractility and caused ventriculo-arterial decoupling with increased EA/EES ratio. This led to reduced cardiac output, blood pressure, and reduced carotid- and renal blood flow.