The most common cause of renal artery stenosis is atherosclerosis, the same condition that causes narrowing of the arteries in coronary heart disease and stroke, and the risk factors are the same as well. Cholesterol plaques build up along the walls of the renal artery and gradually cause narrowing.
Oxytocin is a commonly used uterotonic that can cause significant and even fatal hypotension, particularly when given as a bolus. The resulting hypotension can be produced by a decrease in systemic vascular resistance or cardiac output through a decrease in venous return.
Oxytocin is usually associated with an increase in CO because it decreases systemic vascular resistance (SVR) and causes autotransfusion. Because SVR is not directly monitored, clinicians usually observe a decrease in mean arterial pressure (MAP); when given as a bolus, oxytocin can cause significant reductions in MAP. Mean arterial pressure (MAP) is (approximately) the product of CO and SVR.