What is Cardiogenic Shock?
Cardiogenic shock is a heart-related medical condition where insufficient blood and oxygen are supplied to the body’s tissues. Signs of this condition may involve a decrease in blood pressure (less than or equal to 90 mm Hg for at least 30 minutes) or the necessity for support to maintain this blood pressure. Indicators may also include a urine output of not more than 30 mL/hr or cold extremities. Specific scientific measures of this condition include a low cardiac index (2.2 liters per minute per square meter or less) and a higher than normal pressure in the lung capillaries, over 15 mm Hg.
Cardiogenic shock is identified by a state of reduced blood flow that results in insufficient oxygen being delivered to the body’s organs and tissues. The most frequent cause is acute myocardial infarction, otherwise known as a heart attack. However, other heart-related issues involving heart muscle, valves, electrical system, or the outer layer of the heart can cause cardiogenic shock. Despite progress in restoring blood flow and mechanical support treatments, the rate of illness and death remains high for patients with cardiogenic shock.
What Causes Cardiogenic Shock?
Cardiogenic shock can occur due to various heart dysfunction types. The most common include:
* Sudden lack of blood flow to the heart muscle
* Physical problems with the heart, like damaged heart valves or a blocked heart artery, or an abnormal growth in the heart’s outflow
* Decreased pumping ability of the heart due to disease, irregular rhythms, infection, or a blood clot in the lungs
* Failure of the right side of the heart
* Damage to the main artery from the heart
* Other causes can include some heart-damaging medications, overdosing on certain drugs, chemical imbalances in the body, or abnormal levels of certain minerals.
The risk of experiencing cardiogenic shock after a certain type of heart attack, known as ST-elevation myocardial infarction (STEMI), can increase due to several factors:
* Being over 70 years old
* Having a lower systolic (top number) blood pressure
* Having either a fast or slow heart rate
* A delay in receiving treatment after the onset of symptoms
Risk Factors and Frequency for Cardiogenic Shock
The number of cases of cardiogenic shock, a serious heart condition, is decreasing. This is likely due to more people getting a certain procedure for heart attacks, called a primary percutaneous coronary intervention (PCI). However, this condition can still happen after 5-8% of STEMI and 2-3% of NON-STEMI heart attacks. This means that 40,000 to 50,000 cases happen every year in the United States.
Certain groups have a higher chance of experiencing cardiogenic shock:
- Older people
- People with diabetes
- People who have had damage to the left side of their heart
- Women
Signs and Symptoms of Cardiogenic Shock
Cardiogenic shock is a severe medical condition that can present with a variety of symptoms. Some of the most frequent signs include low blood pressure, changes in mental state, decreased urine production, and cold, sweaty skin. Understanding the patient’s medical history is crucial in determining the cause and managing the condition.
The patient should be evaluated for risk factors for heart problems, which include:
- Diabetes mellitus
- Smoking
- High blood pressure
- High cholesterol
- A family history of early heart disease
- Being over the age of 45 for men and over 55 for women
- Lack of physical activity
Part of diagnosing cardiogenic shock includes a physical exam, looking for the following signs:
- Change in mental state, bluish skin color, cold and sweaty skin, patchy skin coloring on arms and legs
- Weak, fast, and possibly irregular pulse if there’s a heart rhythm problem
- Swelling in the neck veins
- Faint or abnormal heart sounds, such as an extra heart sound (S3 or S4) or a heart murmur if there are issues with the heart valves
- Sounds of fluid buildup in the lungs
- Swelling in the legs and feet due to fluid overload
Testing for Cardiogenic Shock
Quickly diagnosing and treating patients with cardiogenic shock, a severe heart condition, can make a big difference in their health outcomes. There are several ways doctors diagnose cardiogenic shock:
They start by conducting various blood tests to get a clear understanding of the patient’s overall health. These tests measure different chemicals and substances in the blood like magnesium, phosphorous, and a hormone that helps control the thyroid. They also test for coagulation, a process that helps your blood clot to stop bleeding after an injury.
Another test measures arterial blood gases. These gases, found in the blood within the arteries, help doctors determine how well the patients’ lungs are working.
The lactate test shows how well oxygen is being used in the body. Doctors also measure the level of a hormone called brain natriuretic peptide that can help detect heart failure.
Cardiac enzyme tests are another crucial way doctors check for signs of a heart attack. In addition to this, chest x-rays, electrocardiograms, and two-dimensional echocardiographic studies are performed to look closely at the heart and detect any abnormalities.
Doctors also use ultrasonography to regulate fluid management. This helps them determine whether the patients need more or less fluid in their body to support their heart. Lastly, coronary angiography is performed; this process uses dye and special x-rays to show the insides of the coronary arteries, allowing doctors to detect any potential blockages.
Treatment Options for Cardiogenic Shock
Cardiogenic shock, an emergency medical condition, needs to be addressed immediately to prevent irreversible damage to essential body organs. Quick diagnosis followed by immediate medication to maintain blood pressure and respiratory support is crucial for patient prognosis. In cardiogenic shock cases due to a heart attack, restoring the blood flow in the coronary arteries is a vital step in the treatment.
Medical Management
Medical treatment aims to bring back the heart’s functioning and prevent irreversible damage to the body’s vital organs. However, selecting the best medication for cardiogenic shock isn’t straight forward.
– If a patient’s blood pressure is extremely low or doesn’t respond to other medications, norepinephrine is used over dopamine as it carries less risk of arrhythmias and mortality. However, it should be used cautiously as it may increase heart rate and the heart’s oxygen demand, especially in patients who recently had a heart attack.
– Dobutamine is a common drug used in these cases as it can enhance heart muscle contraction, reduce pressure in the left ventricle at the end of the heart’s contraction, and increase blood flow from the heart.
Milrinone, another frequently used drug, can reduce pressure in the left ventricle. Saline or lactated ringer solutions can help hydrate the patient, given no signs of fluid overload are present. Additionally, Aspirin and heparin may be administered to patients with heart attacks or acute coronary syndrome as they have shown effectiveness in reducing mortality.
Bypass Surgeries and Coronary Intervention
Coronary artery bypass grafting and primary percutaneous coronary intervention (PCI) may be recommended to patients based on the severity of the case and their specific coronary anatomy.
Mechanical Circulatory Support
Sometimes, medications aren’t enough, and mechanical circulatory support (MCS) might be required to improve blood flow to body organs. An experienced medical team should assess the need for MCS.
Alternate Therapies
In addition to the standard treatment methods, the patient may be recommended alternate therapies. These include central line placement for fluid resuscitation and continuous blood pressure monitoring, ventilator support for maintaining oxygen levels, insertion of an intra-aortic balloon pump (IABP), percutaneous mechanical devices, or extracorporeal membrane oxygenation (ECMO) if oxygen levels remain low.
In select cases where the patient cannot recover from cardiogenic shock without long-term MCS support, a ventricular assist device can be implanted. For suitable candidates not expected to recover after MCS device implantation, cardiac transplantation may be the last resort.
IAFB, the most commonly used and least expensive mechanical support device, can handle various conditions, including unmanageable angina and heart failure, to bridge the gap to future therapy. The device inflates during diastole and deflates quickly during systole, reducing the afterload. However, patients on IABP need to be on therapeutic anticoagulation like heparin to prevent blood clotting, and regular lab checks are also necessary.
Current management guidelines recommend immediate transfer for PCI. If PCI is not available, open-heart surgery should be considered. If neither option is viable, fibrinolytic therapy should be started. Immediate use of beta-blockers should be avoided. To stabilize the patient, IABP may be used, and an LV assist device should be considered if there are no contraindications.
What else can Cardiogenic Shock be?
- Shock caused by severe infection (Septic shock)
- Shock due to significant blood loss (Hemorrhagic shock)
- Shock triggered by damage to the nervous system (Neurogenic shock)
What to expect with Cardiogenic Shock
Cardiogenic shock is a serious condition that often results in a poor outcome and is the main cause of death in people having a heart attack. Despite receiving the best possible care, about 80% of patients unfortunately do not make it through.
This type of shock can lead to several complications such as:
- Unexpected changes in heart rhythm, known as dysrhythmias
- Sudden stopping of the heart, termed cardiac arrest
- Failure of the kidneys to function properly, referred to as renal failure
- Formation of a bulge in the heart wall, a condition known as ventricular aneurysm
- A stroke, which occurs when blood flow to the brain is cut off
- Thromboembolism, which involves a blood clot travelling to and blocking a blood vessel
- And in the worst case; death
