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.

Ischemia Types Effects of Ischemia, Myocardial ischemia(MI)

• 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 Effects of Ischemia, Myocardial ischemia(MI) ECG

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.

Ischemia Types Effects of Ischemia, Myocardial ischemia(MI) ECG

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.