Internal Medicine · Year 3 · from Internal Medicine

Case 3: Cardiogenic Shock

Patient Presentation

A 62-year-old man with no significant past medical history presents with sudden onset of severe chest pain followed by shortness of breath and near-syncope. EMS found him diaphoretic and hypotensive. In the ED, he appears ashen and confused.

Vital Signs

  • Blood Pressure: 78/52 mmHg
  • Heart Rate: 115 bpm
  • Respiratory Rate: 28/min
  • Oxygen Saturation: 85% on room air
  • Temperature: 36.5°C

Physical Examination

  • General: Critically ill, diaphoretic, cool and mottled extremities
  • HEENT: JVD present
  • Cardiovascular: Tachycardic, S3 gallop, new 3/6 holosystolic murmur at apex
  • Pulmonary: Diffuse crackles
  • Extremities: Cold, mottled, weak pulses

Initial Workup

  • ECG: ST elevation in leads II, III, aVF with reciprocal changes
  • Troponin I: 18.4 ng/mL
  • Lactate: 6.2 mmol/L
  • Creatinine: 2.4 mg/dL
  • Chest X-ray: Pulmonary edema

Clinical Image

Figure 3: 12-lead ECG demonstrating ST-segment elevation in inferior leads (II, III, aVF) with reciprocal ST depression in lateral leads, consistent with acute inferior STEMI.

Image Source: Educational illustration for teaching purposes.

Questions

  1. What defines cardiogenic shock?
  • A) Hypotension requiring vasopressors
  • B) Sustained hypotension (SBP <90 for >30 min) with evidence of tissue hypoperfusion despite adequate filling pressures
  • C) Heart failure with EF <20%
  • D) Any patient requiring inotropic support
  1. What is the most likely cause of the new murmur in this patient?
  • A) Aortic stenosis
  • B) Ventricular septal rupture or acute mitral regurgitation (papillary muscle rupture)
  • C) Tricuspid regurgitation
  • D) Aortic regurgitation
  1. What is the most important intervention for this patient?
  • A) IV diuretics
  • B) Emergent coronary revascularization
  • C) Intra-aortic balloon pump first
  • D) Medical management with inotropes
  1. What hemodynamic parameters characterize cardiogenic shock?
  1. What is the role of mechanical circulatory support in cardiogenic shock?

Answers

  1. B) Sustained hypotension (SBP <90 for >30 min) with evidence of tissue hypoperfusion despite adequate filling pressures - Cardiogenic shock requires hypotension (SBP <90 for 30 min or requiring support) PLUS evidence of end-organ hypoperfusion (altered mental status, cold extremities, elevated lactate, oliguria) with adequate or elevated filling pressures.
  1. B) Ventricular septal rupture or acute mitral regurgitation (papillary muscle rupture) - Mechanical complications of MI include VSR and papillary muscle rupture causing acute severe MR. Both present with new holosystolic murmur and cardiogenic shock. Inferior MI involves the posteromedial papillary muscle.
  1. B) Emergent coronary revascularization - The SHOCK trial demonstrated that early revascularization improves survival in cardiogenic shock complicating acute MI. PCI is preferred; CABG may be needed for mechanical complications.
  1. Hemodynamic parameters in cardiogenic shock:
  • Cardiac index <2.2 L/min/m²
  • Pulmonary capillary wedge pressure >15-18 mmHg (elevated filling pressures)
  • Systemic vascular resistance typically elevated (compensatory vasoconstriction)
  • Mixed venous oxygen saturation <65%
  • Right heart catheterization helps confirm diagnosis and guide therapy
  1. Mechanical circulatory support (MCS) in cardiogenic shock:
  • Intra-aortic balloon pump (IABP): Improves coronary perfusion and reduces afterload; limited mortality benefit
  • Impella: Axial flow pump providing greater hemodynamic support than IABP
  • ECMO (VA-ECMO): For refractory shock; provides biventricular and respiratory support
  • TandemHeart: Percutaneous left atrial-to-femoral artery bypass
  • MCS serves as bridge to recovery, decision, or transplant/durable LVAD

Learning Points

  1. Heart failure classification includes HFrEF (EF ≤40%), HFmrEF (EF 41-49%), and HFpEF (EF ≥50%), each with different management approaches.
  1. GDMT for HFrEF includes four pillars: beta-blocker, ARNI (or ACEi/ARB), MRA, and SGLT2 inhibitor - all with mortality benefit.
  1. HFpEF management focuses on SGLT2 inhibitors, diuretics for congestion, and aggressive treatment of comorbidities.
  1. Cardiogenic shock is a medical emergency requiring early revascularization for MI-related shock and consideration of mechanical circulatory support.
  1. Volume assessment using JVD, orthopnea, edema, and BNP guides diuretic therapy in heart failure.

All cases for this lecture as Markdown