Internal Diseases · MU Sofia

Theory · 25. Ischemic heart disease - myocardial infarction

Covers myocardial infarction as irreversible necrosis after complete coronary occlusion, usually from plaque rupture and thrombus, with less common causes such as spasm and embolism. It walks through the cascade from ischaemia to heart failure, typical and atypical symptoms, examination findings, and laboratory markers. A table lists acute and subacute complications, including Beck's triad and Dressler's syndrome, and the note also describes ECG and echocardiography findings and angiography as the reference investigation.

Inside: 8 sections · 4 labelled pictures · 1 table · 14 flashcards · 3 min

Topic 23 of 88 in the MU Sofia syllabus for Internal Diseases (Dental Medicine, Year 4). The free AceMed note covers it in 8 sections, about 336 words (3 min of reading), with 14 flashcards.

In this note

  1. Ischemic Heart Disease – Myocardial Infarction
  2. Definition
  3. Etiology & Pathogenesis
  4. Symptoms
  5. Physical Examination
  6. Laboratory Tests
  7. Instrumental Tests
  8. Complications

Definition

Irreversible ischemic necrosis (death) of heart muscle due to complete blockage of a coronary artery.

Etiology & Pathogenesis

  • Underlying mechanism: Rupture of an atherosclerotic plaque → thrombus → complete arterial occlusion.
  • Less common causes: Coronary spasm (e.g. cocaine, extreme stress, cold), severe inflammation, embolism.
  • Cascade: Arterial blockage → myocardial ischemia → ↓ contractility → ↓ stroke volume, HR, CO → acute heart failure and possible death.
  • Timeline: >20–40 minutes of ischemia causes irreversible myocyte damage.

Symptoms

  • Chest pain: retrosternal tightness or crushing pain, may radiate to left arm (especially last two fingers), jaw, back, epigastrium; lasts >30 minutes; does not change with position.
  • Autonomic: sweating, nausea, vomiting, fatigue, syncope.
  • Dyspnea (shortness of breath).
  • Heart rate: usually tachycardia, except in septal infarction (AV-node involvement → AV block → bradycardia).
  • Atypical presentations in women, elderly, diabetics, postoperative or critically ill: palpitations, vague discomfort, silent MI.

Physical Examination

  • Skin: cold, clammy, pale.
  • Vital signs: BP may be high (pain, catecholamines) or low (pump failure); HR typically elevated and may be irregular.
  • Lung auscultation: crackles or non-resonant rhonchi if left-sided failure/pulmonary edema.
  • Heart auscultation: possible premature beats; S3 gallop or systolic murmur at apex (due to acute mitral regurgitation from papillary muscle dysfunction).
  • In chronic ischemic cardiomyopathy: arrhythmias and signs of left heart failure or hypertension.

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