What is the difference between stunned and hibernating myocardium?

Definitions: Stunned myocardium is viable myocardium salvaged by coronary reperfusion that exhibits prolonged postischemic dysfunction after reperfusion. Hibernating myocardium is ischemic myocardium supplied by a narrowed coronary artery in which ischemic cells remain viable but contraction is chronically depressed.

What is a stunned myocardium?

“Stunned” myocardium is myocardium that suffers transient reversible myocardial contractile dysfunction induced by acute ischemia wherein the blood supply is almost completely restored on reperfusion and suffers no metabolic deterioration.

How long does it take for stunned myocardium to recover?

In stunned myocardium, contractile function improved significantly at 3 months, without further improvement at 14 months; 61% of the stunned segments improved at 3 months, and 9% improved at 14 months.

Why does the myocardium go into hibernation?

“Hibernating” myocardium is also used to indicate chronic myocardial contractile dysfunction due to ischemia, where there is reduced coronary blood flow at rest and increased myocardial demand will result in impaired contractility.

When does the stunned myocardium return to normal?

Evidence of hibernating myocardium (LV dysfunction) is found in the patient with severe coronary artery stenosis, even in asymptomatic patients at rest. Stunned myocardium returns to normal after a prolonged period of time (hours to weeks). Hibernating myocardium returns to normal function rather quickly if the cause is removed.

How is nuclear imaging used to detect hibernating myocardium?

The use of nuclear imaging to detect hibernating myocardium relies on the demonstration of membrane integrity and/or metabolic activity within the hibernating myocardium. Myocardial retention of the potassium analog 201Tl can be detected by using single photon emission computed tomography (SPECT).

How does hibernating myocardium improve wall thickness?

Hibernating myocardium that may improve in function or thickness after revascularization is identified by those dysfunctional or thinned regions in which hyperenhancement affects <50% wall thickness 7,8.