MYOCARDIAL INFARCTION

                                                          MYOCARDIAL INFARCTION

What is MI?

MI refers to the process by which areas of the myocardial cells in the heart are permanently destroyed.

Definition :

MI is a disease condition which is caused by reduced blood flow in the coronary artery due to atherosclerosis & occlusion of the artery by embolus or thrombus.

Pathophysiology :

Causative factors will lead to atherosclerosis causing inadequate oxygen supply to myocardial cells due to narrowing of coronary arteries followed by cell death causing inflammation & release of cardiac enzymes leading to accumulation of lactic acid due to anerobic glycolysis leading to infarction & chest pain.

Etiology & Risk factors :

Modifiable :

• High blood pressure 
• Stress
• High blood cholesterol
• Obesity
• Smoking & Alcoholism
• Sedentary lifestyle
• Diabetes Mellitus

Non modifiable :

• Age : more than 40 years
• Gender:  Male:Female = 3:1
• Family history : Inherited to children from parents

Types of MI:

Transmural Infarction : Extension of infarcts through the whole  thickness of heart muscle & are usually a result of complete occlusion in the area's blood supply. It is also called as ST Elevation MI [STEMI].

Subendocardial Infarction : Involves the small area in the endocardial wall of left atrium, left ventricles or papillary muscles. It is also called as Non transmural or Non ST Elevation MI [NSTEMI]

Sign & Symptoms :

• Chest pain unrelieved by rest or NTG
• Pain that radiates to arms, jaw, back or neck
• Dyspnea
• Nausea & Vomiting
• Tachycardia > 100 beats/min
• Variable blood pressure
• Anxiety
• Restlessness
• Diaphoresis
• Pale, Cool, Clammy skin
• Death

Medical & Nursing Management :

• Administer oxygen & Aspirin
• AntiArhythmics : Amiodaron
• Antihypertensive to keep BP low ; Hydralazine
• Thrombolytics to reestablish blood flow in occluded artery : streptokinase
• Heparin following thrombolytic therapy
• Calcium channel blockers to prevent reinfarction & ischemia : Verapamil
• Beta adrenergic blockers to reduce duration of ischemic pain & ventricular fibrillation : Propanolol, nadolol, metoprolol
• Analgesics to relieve pain : Morphine
• Nitrates to dilate blood vessels : Nitroglycerine
• Note foe PQRST [Precipitating events, Quality of pain, Radiation of pain, severity of pain, Timing]
• Electrical Cardioversion
• Assess heart sounds & heart murmur
• Assess Cardinal Signs
• Educate patients for lifestyle mofification

Distinctive facts :

• Ix- ECG,Cardiac enzymes :  CK-MB elevated, Troponin-I & Troponin T elevates within 1 hour of MI
• T- wave inversion : Ischemia
• ST elevation/depression : Injury
• Significant Q waves : Infarction
• Also called as Heart Attack
• Silent MI more common in diabetic patient
• Accronym for treatment - MONAT Therapy [Morphine,Oxygen,Nitroglycerine, Aspirin, Thrombolytics]
• Complications include death
• Surgical Rx- PTCA, Stenting, CABG, Athrectomy,
• CPR in case of arrest
• Obstruction of LAD results in Anterior or Septal wall MI
  
• Obstruction of Circumflex artery results in Posterior or Anterior wall MI
• Obstruction of Right Coronary Artery results in Inferior wall MI 

Prognosis :
Prognosis is good in patients receiving appropriate medical attention & lifestyle modification as early as possible. Mortality is however high among patients of MI