In the absence of coronary artery disease, coronary blood flow can be reduced in cardiac tamponade due to the direct effect of pericardial pressure on the epicardium and extracardiac epicardial vessels. Although it has been argued that this reduction is not sufficient to cause myocardial ischemia because of a proportionate decrease in ventricular preload, the compensatory sympathetic outflow leading to tachycardia and increased contractility shifts the balance toward increasing myocardial oxygen demand. More recent reports have demonstrated a marked decline in coronary blood flow due to increased coronary vascular resistance with increasing pericardial pressures, with direct coronary arterial flow studies demonstrating decreased diastolic coronary blood flow and increased retrograde flow in systole.

References

• Abusaid GH, Khalife WI. Reduced coronary blood flow in cardiac tamponade: mystery solved. J Invasive Cardiol. 2012;24:E328-E329.
• Skalidis EI, Kochiadakis GE, Chrysostomakis SI, et al. Effect of pericardial pressure on human coronary circulation. Chest. 2000;117:910-912.