ischemia
(is-kē'mē-ă 
)
[Gr. ischein, to hold back + -emia]
A temporary deficiency of blood flow to an organ or tissue. The deficiency may be caused by diminished blood flow either through a regional artery or throughout the circulation.
ischemic,
(is-kē'mik)
adj.demand -induced i.Insufficient blood flow to meet the needs of the heart produced by tachycardia and relative hypotension rather than by flow-limiting blockages within the coronary arteries. Demand ischemia may occur in atrial fibrillation with a rapid ventricular response, in hypotension or hypovolemia, or in sepsis or the systemic inflammatory response syndrome.
SEE: abdominal angina.
lower limb i.Ischemia to one or both legs due either to chronic arterial obstruction caused by atherosclerosis or to acute obstruction caused by embolism.
Treatment depends on the cause, location, and size of the obstruction. Mild chronic disease may be managed by supportive measures such as smoking cessation, hypertension control, and increased exercise. Medications that improve blood flow (such as aspirin, pentoxifylline and cilostazol) may improve symptoms in patients with intermittent claudication. Surgical procedures for arterial insufficiency in the limbs include arterectomy, balloon angioplasty, bypass grafting, and combinations of all of them. Embolectomy, laser angioplasty, lumbar sympathectomy, patch grafting, stents, thromboendarterectomy, and thrombolytic therapy also may be required. Amputation becomes necessary with failure of reconstructive surgery or development of gangrene, persistent infection, or intractable pain.
Patients with lower limb ischemia related to acute obstruction suffer severe to excruciating pain in the limb, leg pallor and coolness, and absence of palpable pulses below the arterial obstruction. Emergency intervention is required, e.g., thrombolytic therapy, thromboendarterectomy, embolectomy, or other surgical intervention to restore circulation to the affected area. More gradual arterial occlusive disorders may be evidenced by intermittent claudication of the calves on exertion, reduced pulses in the ankles and feet, gradually increasing pallor, hair loss, coolness, pretrophic pain (heralding necrosis and ulceration), and , in the worst circumstances, gangrene of the extremity. Diagnosis is based largely on the patient’s history and physical examination, followed by supportive diagnostic studies such as Doppler ultrasonography and plethysmography, and arteriography.
Instruction to the patient should include explanations of diagnostic tests and procedures, prescribed exercise and medication regimens, proper foot care, and smoking cessation programs. For patients undergoing surgery, fluid and electrolyte balance is assessed, and the patient is prepared emotionally and physically. Postoperatively, vital signs and circulation are monitored; color, temperature, and pulse are compared of the operative limb and the unoperated limb; and the patient is closely observed for hemorrhage (hypotension and tachycardia), chest pain, or other vascular complications. Early ambulation is encouraged. When ischemic limbs or digits need amputation, the stump is checked for drainage, and the amount and color of the drainage are recorded. The stump is elevated according to the surgeon’s or agency’s protocol; pain is carefully assessed and relieved, and phantom limb pain is explained to the patient. Discharge teaching should include plans for rehabilitation (in a rehabilitation center or an outpatient facility), signs to report that could indicate graft occlusion or occlusion at another site, desired and adverse effects related to any medications prescribed, and the importance of scheduled follow-up visits.
mesenteric i.Ischemia in either the superior or inferior mesenteric arteries to the large or small intestine. Mesenteric ischemia is difficult to diagnose without radiologic imaging, e.g., CT angiography. Acute mesenteric ischemia is a surgical emergency.
myocardial i.An inadequate supply of blood and oxygen to meet the metabolic demand s of the heart muscle.
SEE: angina pectoris; atherosclerosis; coronary artery disease.
vertebrobasilar i.Inadequate blood flow through the arteries that supply nutrients and oxygen to the structures at the base of the brain, esp. the brain stem and cerebellum. This can cause difficulties with balance, swallowing, or vision and may be a source of vertigo in some individuals, esp. older adults or those with atherosclerosis.
warm i.The absence of blood flow to a body part or organ intended for transplantation before its removal from a cadaveric donor.