Cardiogenic Shock and Myocardial Infarction

Cardiogenic Shock Overview

• Definition: Cardiogenic shock is a type of "pump failure" shock.
• Common Cause: Infarction (tissue death) of the myocardium due to coronary thrombosis.

Pathophysiology

• Coronary Arteriogram: Visualization technique using arterial branches dividing into smaller branches to show areas supplied by each branch.
• Atheroma Formation: Fatty deposits accumulate, often at bifurcations of arteries, leading to plaques.
  • Plaque Instability: If a plaque becomes unstable, its surface may rupture.
  • Platelet Aggregation: Rupture exposes blood components to thrombogenic core, triggering platelet aggregation ("white thrombus").

Clinical Manifestations

• Low-Risk Unstable Angina: Moderate white thrombus formation, causing chest pain but not complete artery blockage.
• High-Risk Unstable Angina: Increased white thrombus leads to severe chest pains due to significant blood supply reduction.
• Non-ST-Elevation Myocardial Infarction (NSTEMI): More extensive white thrombus leading to partial blockage and myocardial infarction.
• ST-Elevation Myocardial Infarction (STEMI): Red blood clot formation ("red thrombus") causes full blockage and heart muscle death.

Treatment Objectives

• Prevent Progression:
  • Use antiplatelet drugs (e.g., aspirin, clopidogrel) to prevent platelet aggregation.
  • Anticoagulants like low molecular weight heparin to prevent thrombus formation.

Advanced Interventions

• Thrombolysis: Early dissolution of thrombus to restore blood supply and minimize myocardial damage.

Valvular and Rhythm Issues

• Valvular Dysfunction: May require surgical correction.
• Dysrhythmias:
  • Atrial Fibrillation: Treated with medication or defibrillation.
  • Ventricular Tachycardia/Fibrillation: Can lead to cardiac arrest, treatable with defibrillation if unconscious.

Cardiac Arrest Scenarios

• Pulseless Electrical Activity (PEA): Normal ECG without cardiac output, often post-trauma due to blood loss.
• Electromechanical Dissociation: Old term for PEA; electrical activity without mechanical heart action.

Cardiology Medications

• Inotropes: Increase contractility of surviving myocardium.
• Angiotensin-Converting Enzyme (ACE) Inhibitors: Effective for treating congestive heart failure.