Cardiogenic shock

Place in hemodynamic classification

There is no single universally accepted classification of shock states, but modern clinical physiology adopts a basic division into four categories based on the hemodynamic profile: hypovolemic, obstructive, distributive (vascular), and cardiogenic shock.

The cardiogenic type differs fundamentally in that the primary impairment affects the myocardial pumping function itself. Unlike other variants (e.g., massive blood loss or sepsis), the initial problem here lies not in the loss of circulating blood volume or pathological vasodilation, but in the "motor" itself.

Pathogenetic variants

In clinical practice, the pathogenesis of this severe condition is heterogeneous. Three main types of disorders leading to critical hypoperfusion are distinguished:

1. True cardiogenic shock. Develops via a hypokinetic type due to a massive decrease in left ventricular contractility.
2. Shock secondary to hypovolemia. Can be caused by an absolute or relative blood volume deficit. This group also includes reflex shock, an acute hemodynamic response to an intense pain attack.
3. Arrhythmic variant. The drop in cardiac output is a direct consequence of severe rhythm disorders (critical bradyarrhythmias or tachyarrhythmias).

Etiology: structure of causes

According to statistics from the SHOCK registry, the direct causes of cardiogenic shock are distributed as follows:

• 79% — decrease in left ventricular contractility;
• 7% — acute mitral regurgitation (frequently occurs as a complication due to papillary muscle rupture);
• 7% — other factors (including iatrogenic catheterization complications, as well as overdose or unjustified use of calcium channel blockers and β-blockers);
• 4% — interventricular septum rupture (accompanied by pathological left-to-right shunting of blood);
• 2% — isolated right ventricular failure;
• 1.4% — cardiac tamponade (develops upon external rupture of the myocardial wall with blood effusion into the pericardial cavity).

It is important to remember that mechanical complications of infarction (ruptures, muscle avulsions) that trigger shock follow a distinct temporal pattern: this typically occurs between the 4th and 11th day of the disease, when heart tissues undergo lysis (myomalacia).

Stages of development and clinical masks

Clinically, the condition progresses through three classic stages:

1. Preshock.
2. Full-blown picture.
3. Resistant (irreversible) cardiogenic shock.

(A detailed SCAI classification dividing the process into five stages is used separately in specialized practice).

Clinical features: There is a so-called painless form of myocardial infarction. The insidious nature of this form is that primary necrosis proceeds asymptomatically, and early complications—such as various arrhythmias, pulmonary edema, or cardiogenic shock—present as the main and often only symptoms of the developing catastrophe.

Class and exam questions

What else to study on this topic

• Hemodynamic profiles of distributive, hypovolemic, and obstructive shock.
• Clinical markers of tissue hypoperfusion ("windows of shock"): assessment of skin, urine output, and CNS.
• Pathogenesis of septic shock and primary microcirculatory-mitochondrial distress.
• Criteria for massive blood loss and obstetric hemorrhagic shock.
• Delayed autoimmune complications of infarction: Dressler's post-myocardial infarction syndrome.

Other topics in the "Additional Topics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.