Ischemia Types Effects of Ischemia, Myocardial ischemia(MI) ECG ,vertebrobasilar ischemia and other metabolic changes

• A temporary deficiency of blood flow to an organ or tissue,
• Normal muscle contraction and relaxation af­fected
• Angina pectoris has been considered the cardinal symptom of myocardial ischemia for more than two centuries.

• LVF (left ventricular failure)
• Papillary muscle dysfunction ~MR ~LV dilata-
• LVF
• Angina pectoris
• Myocardial necrosis and scarring
• MI
• Akinesis
• Dyskinesis.
• between 25 and 45 percent of patients with acute and chronic ischemic syndromes have evidence of myocardial ischemia during daily life,

Types of Ischemia —

myocardial ischemia (MI):

• evidence of myocardial ischemia in the absence of chest discomfort or other anginal equivalents.
• An inadequate supply of blood and oxygen to meet the metabolic demands of the heart muscle.
• Exercise testing or ambulatory monitoring shows transient ST segment changes

vertebrobasilar ischemia:

• 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).

lower limb ischemia:

• An inadequate blood flow to one or both legs due either to chronic arterial obstruction caused by atherosclerosis or to acute obstruction caused by embolism.

Metabolic Changes

• Accumulation of lactic acid, depletion (wash out) of high energy phosphates, oxygen and creatine phos­phate.
• In the presence of oxygen, fatty acid and glucose are metabolized to carbon dioxide and water.
• Fatty acids, glucose O₂ co_{2 —–>} and H₂0.
• In absence of oxygen fatty acids and glucose are metabolized to lactic acid which  promotes coronary spasm,
• Changes are reversible up to 10 minutes .
• after 20 minutes changes are irreversible.

ECG Changes

• typical changes of angina / IHD are:
• ST depression
• T inversion
• These are seen in contiguous leads like 2, 3, AVF, ferior wa or I, L, V5,V6 (lateral wall).
• severe ischemia, ST elevation is seen and indi­:c~es transmural ischemia; it may evolve into ‘: myocardial infarction).
• eIedrical instabilit~ads to arrhythmias – VT-(ven­:-icular tachycardia) -.and VF-(ventricular fibril~ation).
• death occurs due to pump failure or ventricular :tachyarrhythymias.