Cardiogenic shock is a condition of inadequate tissue perfusion due to decreased cardiac output. It is a frequently fatal complication of a variety of disorders, occurring most commonly following acute myocardial infarction.
Cardiogenic shock patients are brought to the emergency room presenting with a spectrum of signs and symptoms that represents a different phase of the clinical condition, from inciting event to end stage organ failure.
The following system wise presentation of signs and symptoms are commonly seen in cardiogenic shock and its inciting events:
Cardiogenic shock often presents as an emergency and they are diagnosed clinically by their characteristic sign and symptoms. The following diagnostic tests are also performed with patients suffering of cardiogenic shock:
Patients in cardiogenic shock usually come in the emergency room illegible for advanced life support like ventilators, continuous oxygenation and intravenous access for medications. Some patients may require medications to increase blood flow through the heart and improve the heart pump muscles. The following medications are usually used in cardiogenic shock and heart attacks:
Invasive medical approach to cardiogenic shock includes: Angioplasty, stenting, and balloon pumps . Where medical approach are futile, the following cardiovascular procedures may be done in cardiogenic shock:
The mortality rate of patients with cardiogenic shock among myocardial infarction patients is very high and despite expert medical care at 50-60% .
The key to the survival of cardiogenic shock patients in ischemia or infarction of the heart is the rapid identification of the clinical disease, prompt fluid resuscitation, and immediate coronary artery revascularization . The demonstration of a right ventricular dilatation and infarction by voltage in an electrocardiogram confers a poor outcome among patients .
When cardiogenic shock is left unmitigated, the following complications may arise as a result:
Cardiogenic shock occurs when the heart becomes dysfunctional and is unable to keep up with the body’s needs. The most common causes are serious cardiac complications that occur during a myocardial infarction, the most common etiology includes:
In the United States, the incidence of cardiogenic shock among heart attack patients ranges from 5% to 10%. Although, a community-wide analysis done in the Worcester Heart Attack study conveyed an average of 7.5% incidence of cardiogenic shock during heart attacks .
In ST-elevation myocardial infarction (STEMI), cardiogenic shock occurs in 8.6% of patients. In Europe, relative incidence of cardiogenic shock averages at 7% among MI cases. The Hispanic race has the highest mortality rate for cardiogenic shock reaching a 74% level. There is a male predisposition of cardiogenic shock mortality of up to 58%.
Cardiogenic shock represents an acute deterioration of the heart pump muscle affecting up to 40% of the left ventricular muscle function. Heart conditions that leads to this state includes myocardial infarction, myocardial ischemia, advanced cardiomyopathy, acute myocarditis, uncontrolled arrhythmia, and valvular dysfunction.
The cardiac muscle pathophysiology is based on the hypoperfusion state of the heart muscle causing an increased cardiac demand but poor cardiac output. This vicious cycle pattern leads to cardiogenic shock and gives rise to its characteristic symptoms. The prolonged tissue hypoperfusion will lead to anaerobic glycolysis and the accumulation of lactic acid which results in intracellular acidosis.
The acidotic state will breakdown the lysosomes and cause myonecrosis of the heart muscles at the site of ischemia or infarction. In some cases of myocardial hypoperfusion, the heart muscle becomes stunned or hibernates into a reversible state of functionality where it may resume to function normally after adequate revascularization to the heart muscle happens.
The dysfunctional left ventricle in the myocardial infarction or ischemia will increase its diastolic filling end-pressure, the diminished state of cardiac compliance will lead to the accumulation of the blood in the lungs and presents with pulmonary congestion. The diminished blood flow to the brain may lead to cortical signs of confusion, altered state of sensorium, agitation and flaccid coma.
The most effective way to prevent the occurrence of a cardiogenic shock is to directly prevent the occurrence of a heart attack that causes it. The following lifestyle modifications are done to prevent a heart attack:
Cardiogenic shock is a clinical condition where the heart as a pump is no longer able to perfuse the tissues adequately which causes significant hypoxia in the presence of adequate blood volume. Cardiogenic shock is the most common cause of death in acute myocardial infarction (MI) despite advances in medical care .
Cardiogenic shock is considered as a rare and fatal physiologic state caused by heart dysfunction at systole. There is usually a sustained form of hypotension occurring below 90 mmHg for at least 30 minutes, a reduced cardiac index of less than 2.2 l/min/m2, and increase in capillary wedge pressure of more than 15 mmHg. Tissue hypoxemia is clinical seen as cyanosis, oliguria, altered sensorium and cool extremities.
Cardiogenic shock is a medical condition wherein the heart is no longer capable to pump effectively and preserve adequate tissue perfusion.
History and physical examination is the mainstay in emergency diagnosis. This may be augmented with ECG, Chest X-ray and Echocardiogram.
Treatment and follow-up