Myocardial Infraction | Heart Attack | Pathophysiology | Symptoms | Treatment | An Overview

 Myocardial Infraction (M.I.) | हार्ट अटैक 

➥ Acute myocardial infarction जिसे हार्ट अटैक या coronary occlusion के रूप में भी जाना जाता है।

➥ It is a life-threatening condition characterized by the formation of localized necrotic area (infraction) within the myocardium, यह तब होता है जब myocardial tissue अचानक और गंभीर रूप से oxygen से वंचित (deprived) हो जाता है।

➥ Myocardial infarction usually follows the sudden occlusion of coronary artery and abrupt stopping of blood and oxygen flow to the myocardial muscle.

➥ The most common site of M.I. is the anterior wall of left ventricle.

Pathophysiology

Coronary atherosclerosis / coronary heart disease

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Ischemia

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Hypoxia

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Myocardial damages

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Necrosis

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Myocardial infarction

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Myocardial fibrosis

 

Etiology

➥ Myocardial infarction का सबसे आम कारण, coronary artery के complete या लगभग complete occlusion (90% of M.I)

➥ Atherosclerotic plaque rupture into the vessel lumen result in artery occlusion.

➥ Endothelial injury to coronary artery may participate platelets aggregation and cause thrombus formation.

➥ Severe coronary artery disease participates thrombus formation.

Clinical manifestation

 A) Cardiovascular symptoms:

            ➥ Severe substernal chest pain of squeezing in nature.

            ➥ Pain may radiate to left arm, shoulder neck and jaw.

            ➥ Continuous for more than 15 minute.

B) Respiratory symptoms:

             ➥ सांस लेने में तकलीफ, dyspnea, tachypnea, pulmonary edema may be present.

C) Gastrointestinal symptoms:

             ➥ जी मिचलाना और उल्टी होना, कब्ज होना।

D) Genitourinary symptoms: 

             ➥ पेशाब कम होना cardiogenic shock का संकेत हो सकता है

E) Skin symptoms: 

             ➥ ठंडी, diaphoretic pale appearance skin.

F) Neurological symptoms:

              ➥ चिंता, बेचैनी, सिरदर्, visual disturbance, altered speech, loss of consciousness.

 

Diagnostic finding

A) ECG

     ➥ ST segment depression और T wave inversion ischemia के pattern का संकेत देते हैं।

     ➥ ST segment elevation indicate injury pattern

     ➥ Abnormal Q wave indicate tissue necrosis and are permanent changes.

B) Laboratory test

    ➧ Elevation of myoglobin: हालांकि myoglobin is the first cardiac makers to become elevated after MI, it lacks cardiac specificity and is excreted in the urine rapidly.

Oxygen binding protein in myocardium level rises within 2 hours after cell death with a rapid decline in the level after 7 hours.

 

    ➧ Elevation of troponin: (it is a protein found in myocardium)

        Troponin has three components (isomer)

• Troponin - I
• Troponin - C
• Troponin - T

  ➥ It is the most important & specific marker ( Trop- I & Trop- T) for myocardial damage.

  ➥ Protein released by cardiac/ skeletal muscle.

  ➥ Level usually increase after 3-6 hours of M.I. & reaches to peak at 24 hours remain in blood for 7-14 days.

  ➥ Test is repeated two more time over the next 6 to 24 hours after the episode of suspected M.I.

  ➥ Level in M.I. > 0.01 ng/ml

 

      ➧ Creatine kinase: These are three isoenzyme

            • CK-MM – derived from skeletal muscles

            • CK-BB – Derived from brain and lungs and

            • CK-MB – Mainly derived from cardiac muscle.

➥ Elevation of creatine kinase (CK-MB): level rises within 6 hours after onset of chest pain, level peaks within 18 hours after death of cardiac tissue.

➥ CK-MB disappears from blood after 48-72 hours of MI.

➥ Sample should be taken immediately on admission and every 6 to 8 hours for the first 24 hours

 

     ➧ Elevation of lactate dehydrogenase (LDH): 

➥ Myocaridial specific.

➥ यदि LDH1 की serum concentration, LDH2 की concentration से अधिक है, तो पैटर्न को “flipped” कहा जाता है, जो myocardial necrosis को दर्शाता है।

➥ LDH level rises 24 hours after M.I., level peaks between 48 and 72 hours and fall to normal in 7 to 14 days.

 

Management

➤ Emergency care:

        ➥ Patient को quite और शांत रखें

        ➥ सिर को ऊपर उठाएं और गर्दन के आस-पास के तंग कपड़ों को ढीला कर दें।

        ➥ Continuous cardiac monitoring

        ➥ Semi fowler position प्रदान करें

        ➥ Oxygen administration by nasal canula.

        ➥ यदि Patient बेहोश हो जाता है, तो तत्काल CPR का उपयोग किया जाना चाहिए

 

➤ Pharmacologic therapy:

        ➥ Thrombolytic agents:  Tissue plasminogen activator (t-PA), streptokinase, urokinase.

        ➥ Antiplatelets therapy : Aspirin

        ➥ Anticoagulant therapy: Heparin ( Claxan)

        ➥ Vasodilator therapy: Nitro-glycerine (IV. or sublingually)

 

Complications of M.I.

👉 Dysrythmias

👉 Heart failure

👉 Recurrent M.I.

👉 Cardiogenic shock

👉 Pulmonary edema

👉 Pericarditis

 

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