Heart ischemia, known as myocardial ischemia, occurs when the heart muscle is partially or completely cut off from its blood supply, according to Mayo Clinic. Blocked coronary arteries interfere with blood flow, preventing the heart from receiving an adequate amount of oxygen.
An individual with a constricted or mildly blocked artery may only suffer from ischemia when physically active or feeling stress, WebMD notes. Chronic ischemia is more likely to develop from severe narrowing of the arteries, causing symptoms of angina, such as pain and tightness in the chest, arm, neck or shoulder. The person may also feel nauseous, sweaty or short of breath. In some cases, individuals suffer from silent ischemia, which occurs without symptoms. Silent ischemia is often diagnosed after a stress test or electrocardiogram shows signs of reduced blood flow.
Myocardial ischemia can develop gradually or suddenly and often manifests as a symptom of other cardiac conditions, such as blood clots or coronary artery disease, Mayo Clinic states. Factors such as smoking, obesity, inactivity, high blood pressure and high cholesterol can increase the risk of suffering from ischemia. Recurrent episodes of ischemia can weaken the heart muscle, triggering an irregular heartbeat or making the heart less effective at pumping blood. Severe blockage of the arteries can also cause a heart attack and result in permanent cardiac damage.