Question

1. Cardiogenic shock results from a serious heart condition such as a myocardial infarction, slow or dangerous heart rhythms, or even ruptures to the valves or walls of the heart. Describe how cardiogenic shock would impact cardiac output and mean arterial pressure, then describe how the autonomic nervous system would respond to this. How could this response be potentially detrimental to both the heart and organs? You do not need to detail specific receptors and chemicals in the autonomic response.

Answer 1

Cardiogenic shock is a medical emergency where the heart is unable to pump adequate blood to the tissues - tissue hypoperfusion occurs. Here the ventricular filling is normal, but the contractility of the ventricular muscles are affected. Myocardial infarction, slow or dangerous heart rhythms, and ruptures to the valves or walls of the heart causes cardiogenic shock beacuse all these conditions affect the ability of ventricles to pump blood.

Cardiac output is reduced and inturn the mean blood pressure also decreased. As the cardiac output is reduced, it perpetuate further myocardial ischemia and contractility is severely affected. Condition will get worsened.

As a compensatory mechanism to low BP and low cardiac output - - >Parasympathetic activity decreased and Sympathetic activity increased

• SA node : increased heart rate
• Ventricular myocardium : increased heart contractility
• Arterioles : Vasoconstriction - - - > increased peripheral resistance which leads to increased mean arterial pressure.

Peripheral vasoconstriction increases the blood flow to heart, but it also increases afterload which worsens hypoperfusion of tissues. It also causes impairment of the myocardium and increased oxygen demand which worsens myocardial ischemia.

The increased heart rate and contractility will results in increased oxygen demand for myocardial muscles and again worsens myocardial ischemia.

When the left ventricule function impaired, pressure transmits to left atrium which eventually cause pulmonary congestion and again worsens hypoxia.

Hypoxia and hypoperfusion leads to multiorgan failure.