Cardiogenic shock
Encyclopedia
Cardiogenic shock is based upon an inadequate circulation of blood
due to primary failure of the ventricle
s of the heart
to function effectively.
Since this is a type of shock there is insufficient perfusion
of tissue
(i.e. the heart
) to meet the required demands for oxygen
and nutrients. Cardiogenic shock is a largely irreversible condition and as such is more often fatal than not. The condition involves increasingly more pervasive cell
death from oxygen
starvation (hypoxia
) and nutrient starvation (e.g. hypoglycemia
). Because of this it may lead to cardiac arrest
(or circulatory arrest) which is an acute cessation of cardiac pump function.
Cardiogenic shock is defined by sustained hypotension
with tissue hypoperfusion despite adequate left ventricular filling pressure. Signs of tissue hypoperfusion include oliguria
(<30 mL/h), cool extremities, and altered level of consciousness.
muscle, most often from a large myocardial infarction
. Other causes include arrhythmia, cardiomyopathy
, cardiac valve problems, ventricular outflow obstruction (i.e. aortic valve stenosis
, aortic dissection
, systolic anterior motion (SAM) in hypertrophic cardiomyopathy
) or ventriculoseptal defects.
may show poor ventricular function, signs of PED, ventricular septal rupture (VSR), an obstructed outflow tract or cardiomyopathy.
.
of heart muscle may be needed to make a definite diagnosis
. but biopsy should only be done when third space is suspected
. In case of cardiac arrhythmia several anti-arrhythmic agents may be administered, i.e. adenosine, verapamil
, amiodarone
, β-blocker
or glucagon
. Positive inotropic agents
, which enhance the heart's pumping capabilities, are used to improve the contractility and correct the hypotension. Should that not suffice an intra-aortic balloon pump
(which reduces workload
for the heart, and improves perfusion of the coronary arteries) can be considered or a left ventricular assist device
(which augments the pump-function of the heart). Finally, as a last resort, if the patient can be made stable enough and otherwise qualifies, cardiac transplantation can be performed. These invasive measures are important tools- more than 50% of patients who do not die immediately due to cardiac arrest from a lethal arrthythmia and live to reach the hospital (who have usually suffered a severe acute myocardial infarction, which in itself still has a relatively high mortality rate), die within the first 24 hours. The mortality rate for those still living at time of admission who suffer complications (among others, cardiac arrest or further arrhythmias, heart failure, cardiac tamponade, a ruptured or dissecting aneurysm, or another heart attack) from cardiogenic shock is even worse around 85%, especially without drastic measures such as ventricular assist devices or transplantation.
Cardiogenic shock may be treated with intravenous dobutamine
, which acts on β1 receptors of the heart leading to increased contractility and heart rate.
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
due to primary failure of the ventricle
Ventricle (heart)
In the heart, a ventricle is one of two large chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs. The Atria primes the Pump...
s of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
to function effectively.
Since this is a type of shock there is insufficient perfusion
Perfusion
In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. The word is derived from the French verb "perfuser" meaning to "pour over or through."...
of tissue
Biological tissue
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
(i.e. the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
) to meet the required demands for oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and nutrients. Cardiogenic shock is a largely irreversible condition and as such is more often fatal than not. The condition involves increasingly more pervasive cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
death from oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
starvation (hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
) and nutrient starvation (e.g. hypoglycemia
Hypoglycemia
Hypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...
). Because of this it may lead to cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
(or circulatory arrest) which is an acute cessation of cardiac pump function.
Cardiogenic shock is defined by sustained hypotension
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
with tissue hypoperfusion despite adequate left ventricular filling pressure. Signs of tissue hypoperfusion include oliguria
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...
(<30 mL/h), cool extremities, and altered level of consciousness.
Etiology
Cardiogenic shock is caused by the failure of the heart to pump effectively. It can be due to damage to the heartHeart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
muscle, most often from a large myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
. Other causes include arrhythmia, cardiomyopathy
Cardiomyopathy
Cardiomyopathy, which literally means "heart muscle disease," is the deterioration of the function of the myocardium for any reason. People with cardiomyopathy are often at risk of arrhythmia or sudden cardiac death or both. Cardiomyopathy can often go undetected, making it especially dangerous to...
, cardiac valve problems, ventricular outflow obstruction (i.e. aortic valve stenosis
Aortic valve stenosis
Aortic valve stenosis is a disease of the heart valves in which the opening of the aortic valve is narrowed. The aortic valve is the valve between the left ventricle of the heart and the aorta, which is the largest artery in the body and carries the entire output of blood.-Pathophysiology:The...
, aortic dissection
Aortic dissection
Aortic dissection occurs when a tear in the inner wall of the aorta causes blood to flow between the layers of the wall of the aorta and force the layers apart. The dissection typically extends anterograde, but can extend retrograde from the site of the intimal tear. Aortic dissection is a medical...
, systolic anterior motion (SAM) in hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy is a disease of the myocardium in which a portion of the myocardium is hypertrophied without any obvious cause...
) or ventriculoseptal defects.
Signs and symptoms
- Anxiety, restlessness, altered mental stateGlasgow Coma ScaleGlasgow Coma Scale or GCS is a neurological scale that aims to give a reliable, objective way of recording the conscious state of a person for initial as well as subsequent assessment...
due to decreased cerebral perfusion and subsequent hypoxiaHypoxia (medical)Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
. - Hypotension due to decrease in cardiac outputCardiac outputCardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...
. - A rapid, weak, thready pulse due to decreased circulation combined with tachycardia.
- Cool, clammy, and mottled skin (cutis marmorataCutis marmorataWhen a newborn infant is exposed to low environmental temperatures, an evanescent, lacy, reticulated red and/or blue cutaneous vascular pattern appears over most of the body surface...
), due to vasoconstriction and subsequent hypoperfusion of the skin. - Distended jugular veinJugular veinThe jugular veins are veins that bring deoxygenated blood from the head back to the heart via the superior vena cava.-Internal and external:There are two sets of jugular veins: external and internal....
s due to increased jugular venous pressure. - Oliguria (low urine output) due to insufficient renal perfusion if condition persists.
- Rapid and deep respirations (hyperventilation) due to sympathetic nervous system stimulation and acidosis.
- Fatigue due to hyperventilation and hypoxia.
- Absent pulse in tachyarrhythmia.
- Pulmonary edemaPulmonary edemaPulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
, involving fluid back-up in the lungs due to insufficient pumping of the heart..
Electrocardiogram
An electrocardiogram helps establishing the exact diagnosis and guides treatment, it may reveal:- Cardiac arrhythmias
- Signs of cardiomyopathyCardiomyopathyCardiomyopathy, which literally means "heart muscle disease," is the deterioration of the function of the myocardium for any reason. People with cardiomyopathy are often at risk of arrhythmia or sudden cardiac death or both. Cardiomyopathy can often go undetected, making it especially dangerous to...
Ultrasound Examination
EchocardiographyEchocardiography
An echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart . Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart...
may show poor ventricular function, signs of PED, ventricular septal rupture (VSR), an obstructed outflow tract or cardiomyopathy.
Swan-ganz catheter
The Swan-ganz catheter or pulmonary artery catheter may assist in the diagnosis by providing information on the hemodynamicsHemodynamics
Hemodynamics, meaning literally "blood movement" is the study of blood flow or the circulation.All animal cells require oxygen for the conversion of carbohydrates, fats and proteins into carbon dioxide , water and energy in a process known as aerobic respiration...
.
Biopsy
In case of suspected cardiomyopathy a biopsyBiopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
of heart muscle may be needed to make a definite diagnosis
Diagnosis
Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many different disciplines with variations in the use of logics, analytics, and experience to determine the cause and effect relationships...
. but biopsy should only be done when third space is suspected
Treatment
In cardiogenic shock: depending on the type of myocardal infarction one can infuse fluids or in shock refractory to infusing fluids inotropicaInotrope
An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions...
. In case of cardiac arrhythmia several anti-arrhythmic agents may be administered, i.e. adenosine, verapamil
Verapamil
Verapamil is an L-type calcium channel blocker of the phenylalkylamine class. It has been used in the treatment of hypertension, angina pectoris, cardiac arrhythmia, and most recently, cluster headaches. It is also an effective preventive medication for migraine...
, amiodarone
Amiodarone
Amiodarone is an antiarrhythmic agent used for various types of tachyarrhythmias , both ventricular and supraventricular arrhythmias. Discovered in 1961, it was not approved for use in the United States until 1985...
, β-blocker
Beta blocker
Beta blockers or beta-adrenergic blocking agents, beta-adrenergic antagonists, beta-adrenoreceptor antagonists or beta antagonists, are a class of drugs used for various indications. They are particularly for the management of cardiac arrhythmias, cardioprotection after myocardial infarction ,...
or glucagon
Glucagon
Glucagon, a hormone secreted by the pancreas, raises blood glucose levels. Its effect is opposite that of insulin, which lowers blood glucose levels. The pancreas releases glucagon when blood sugar levels fall too low. Glucagon causes the liver to convert stored glycogen into glucose, which is...
. Positive inotropic agents
Inotrope
An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions...
, which enhance the heart's pumping capabilities, are used to improve the contractility and correct the hypotension. Should that not suffice an intra-aortic balloon pump
Intra-aortic balloon pump
The Intra-aortic balloon pump ' is a mechanical device that increases myocardial oxygen perfusion while at the same time increasing cardiac output. Increasing cardiac output increases coronary blood flow and therefore myocardial oxygen delivery...
(which reduces workload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...
for the heart, and improves perfusion of the coronary arteries) can be considered or a left ventricular assist device
Ventricular assist device
A Ventricular assist device, or VAD, is a mechanical circulatory device that is used to partially or completely replace the function of a failing heart...
(which augments the pump-function of the heart). Finally, as a last resort, if the patient can be made stable enough and otherwise qualifies, cardiac transplantation can be performed. These invasive measures are important tools- more than 50% of patients who do not die immediately due to cardiac arrest from a lethal arrthythmia and live to reach the hospital (who have usually suffered a severe acute myocardial infarction, which in itself still has a relatively high mortality rate), die within the first 24 hours. The mortality rate for those still living at time of admission who suffer complications (among others, cardiac arrest or further arrhythmias, heart failure, cardiac tamponade, a ruptured or dissecting aneurysm, or another heart attack) from cardiogenic shock is even worse around 85%, especially without drastic measures such as ventricular assist devices or transplantation.
Cardiogenic shock may be treated with intravenous dobutamine
Dobutamine
Dobutamine is a sympathomimetic drug used in the treatment of heart failure and cardiogenic shock. Its primary mechanism is direct stimulation of β1 receptors of the sympathetic nervous system. Dobutamine was developed by a laboratory led by Drs...
, which acts on β1 receptors of the heart leading to increased contractility and heart rate.
External links
- Cardiogenic Shock by eMedicineEMedicineeMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely, two medical doctors. The website is searchable by keyword and consists of approximately 6,800 articles, each of which is associated with one of 62 clinical subspecialty textbooks...