Pathophysiology of cardiogenic shock

2021-04-29 04:48 PM

Shock is often caused by inadequate cardiac output. Therefore, any condition that reduces cardiac output below normal levels can lead to cardiac shock.

Cardiogenic shock (or heart shock) means inadequate blood flow through the body, to the point where body tissues are damaged, especially due to too little oxygen and other nutrients being supplied to the tissue cells. Even the cardiovascular system itself - the heart muscle, the walls of the blood vessels, the vasomotor system, and other circulatory organs - starts to deteriorate, so shock, once initiated, becomes more likely. worse than.

Cardiogenic shock with decreased cardiac output

Shock is often caused by inadequate cardiac output. Therefore, any condition that reduces cardiac output below normal levels can lead to cardiac shock. Two types of factors can seriously reduce cardiac output:

1. Heart abnormalities that decrease the heart's ability to pump blood. These abnormalities include in particular myocardial infarction, but also states of heart toxicity, severe valve dysfunction, arrhythmia, and others.

Up to 70% of people with cardiogenic shock do not survive.

2. Factors that decrease venous flow also decrease cardiac output because the heart cannot pump as blood does not return. The most common cause of decreased venous blood return is a decrease in blood volume, but venous blood return may also decrease due to decreased vascular tone, especially of venous storage tanks, or interfering with blood flow. at some point in the circulation, especially in the return of veins to the heart.

Cardiogenic shock is not caused by decreased cardiac output

Sometimes, the cardiac output is normal or even greater than normal, but the patient is in cardiogenic shock. This condition can be caused by (1) an excessive metabolic rate, so even normal cardiac output isn't enough, or (2) an abnormal tissue perfusion pattern, so most cardiac output goes away. through blood vessels next to those that provide nourishment to local tissues.

For now, it's important to note that they all lead to an inadequate supply of nutrients to vital tissues and organs, as well as inadequate removal of cellular waste from the tissue.

Hemodynamic in cardiogenic shock

According to the mind of many doctors, the level of arterial pressure is the primary measure of the adequacy of circulatory function. However, arterial pressure can often be severely misaligned. Sometimes, a person can experience severe shock and still have near-normal arterial pressure because the strong nerve reflex keeps the pressure from dropping. At other times, the arterial pressure may drop to half of normal, but the patient still has normal tissue perfusion and is not in shock.

In most types of shock, especially shock due to severe blood loss, arterial blood pressure decreases, and cardiac output decreases, though usually not by much.

Tissue damage during cardiogenic shock

Once a cardiogenic shock reaches a serious condition, regardless of its initial cause, the shock itself will lead to more shock. That is, inadequate blood flow, causes body tissues to begin to deteriorate, including the heart and circulatory system. This impairment causes an even greater decrease in cardiac output, and a vicious cycle ensues with increasing cardiac shock, less tissue perfusion, more shock, etc. until death. It is with this final stage of cardiogenic shock, of particular concern, since proper treatment can often reverse fatal slippage.

Stages of cardiogenic shock

Because the characteristics of cardiogenic shock vary with different degrees of severity, people often divide shock into three main stages:

1. The restorative phase (sometimes called the compensatory phase), in which normal cyclic compensation mechanisms eventually cause complete recovery without external help.

The progressive phase, in which, if left untreated, shock worsens until death.

3. The irreversible stage in which shock has progressed to the point that all known forms of therapy are incapable of saving the patient's life even though the patient is still alive.

 

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