Cardiogenic shock is a state in which a weakened heart isn't able to
pump enough blood to meet the body's needs. It is a medical
emergency and is fatal if not treated right away. The most common
cause of cardiogenic shock is damage to the heart muscle from a
severe heart attack.
Not everyone who has a heart attack develops cardiogenic shock. In
fact, less than 10 percent of people who have a heart attack
develop it. But when cardiogenic shock does occur, it's very
dangerous. For people who die from a heart attack in a hospital,
cardiogenic shock is the most common cause.
The medical term "shock" refers to a state in which not enough
blood and oxygen reach important organs in the body, such as the
brain and kidneys. In a state of shock, a person's blood pressure is
When a person is in shock (from any cause), not enough blood or
oxygen is reaching the body's organs. If shock lasts more than several
minutes, the lack of oxygen to the organs starts to damage them. If
shock isn't treated quickly, the organ damage can become
permanent, and the person can die.
The most common initiating event in cardiogenic shock is AMI. Dead
myocardium does not contract, and classical teaching has been that
when more than 40% of the myocardium is irreversibly damaged
(particularly, the anterior cardiac wall), cardiogenic shock may
result. On a mechanical level, a marked decrease in contractility
reduces the ejection fraction and cardiac output. These lead to
increased ventricular filling pressures, cardiac chamber dilatation,
and ultimately univentricular or biventricular failure that result in
systemic hypotension and/or pulmonary edema.
A systemic inflammatory response syndrome–type mechanism has
been implicated in the pathophysiology of cardiogenic shock.
Elevated levels of white blood cells, body temperature,
complement, interleukins, and C-reactive protein are often seen in
large myocardial infarctions. Similarly, inflammatory nitric oxide
synthetase (iNOS) is also released in high levels during myocardial
stress. iNOS induces nitric oxide production, which may uncouple
calcium metabolism in the myocardium resulting in a stunned
myocardium. Additionally, iNOS leads to the expression of
interleukins, which may themselves cause hypotension.
Myocardial ischemia causes a decrease in contractile function, which
leads to left ventricular dysfunction and decreased arterial pressure;
these, in turn, exacerbate the myocardial ischemia. The end result is
a vicious cycle that leads to severe cardiovascular decompensation.
The vast majority of cases of cardiogenic shock in adults are
due to acute myocardial ischemia.
Systolic -Beta-blocker overdose, calcium channel blocker
overdose, myocardial contusion, respiratory acidosis,
hypocalcemia, hypophosphatemia, and cardiotoxic drugs (eg,
Diastolic - Ventricular hypertrophy and restrictive
After load -Aortic stenosis, hypertrophic cardiomyopathy,
dynamic outflow obstruction, aortic coarctation, and malignant
Valvular/structural -Mitral stenosis, endocarditis, myocarditis,
mitral or aortic regurgitation, atrial myxoma or thrombus,
pericardial tamponade & pulmonary embolism.
Risk factors for the development of cardiogenic shock include
preexisting myocardial damage or disease (eg, diabetes,
advanced age, previous AMI(acute MI), AMI (eg, Q-wave, large
or anterior wall AMIs), congenital heart disease, and
Signs & symptoms:
Profuse sweating, moist skin
Tachycardia & tachypnea
Restlessness, agitation, confusion due to decreased cerebral
perfusion and subsequent hypoxia.
Skin that feels cool to the touch
Pale skin color or blotchy (mottled) skin
Rapid & Weak (thready) pulse
Decreased mental status - Loss of ability to concentrate & Loss
Decreased or no urine output
Hypotension due to decrease in cardiac output
Distended jugular veins due to increased jugular venous
DiagnosisBlood pressure. very low blood pressure, the most common sign of
ECG (electrocardiogram). diagnose severe heart attack & and
monitor heart's condition.
Chest X-ray.. A chest X-ray shows whether the heart is enlarged or
whether there is fluid in the lungs, which can be signs of cardiogenic
Echocardiography. This test uses sound waves to create a moving
picture of your heart. Echocardiography provides information about
the size and shape of your heart and how well your heart chambers
and valves are working. The test also can identify areas of heart
muscle that aren't contracting normally. Not enough blood is flowing
to these areas.
Coronary angiography. passing a catheter (a thin, flexible tube)
through an artery in leg or arm to heart. The catheter can measure
the pressure inside the various chambers of your heart. A dye that
can be seen on X-ray is injected into the blood through the tip of the
catheter. The dye allows to study the flow of blood through the heart
and blood vessels and see any blockages that exist.
Arterial blood gas measurement. In this test, a blood sample is taken
from an artery to measure oxygen, carbon dioxide, and pH (acidity)
in the blood..
Cardiac enzymes. When cells in the heart die, they release enzymes
into the blood called markers or biomarkers. Measuring these
markers can show whether the heart is damaged and the extent of
the damage. Cardiac biomarkers (eg, creatine kinase, troponin,
Coagulation profile (eg, prothrombin time, activated partial
Tests that measure the function of various organs, such as the
kidneys and liver. If these organs aren't working right, it could be a
sign that they aren't getting enough blood and oxygen, which could
be a sign of cardiogenic shock.
Brain natriuretic peptide (BNP) may be useful as an indicator of
congestive heart failure and as an independent prognostic indicator
of survival. A low BNP level may effectively rule out cardiogenic
shock in the setting of hypotension; however, an elevated BNP level
does not rule in the disease.
TreatmentEmergency life support- Emergency life support is a necessary
treatment for most people who have cardiogenic shock.
- Giving extra oxygen to breathe to minimize damage to your
- If necessary, connected to a breathing machine (ventilator).
- Receiving medications and fluid through an intravenous (IV)
line in your arm.
Vasopressors- These drugs increase both coronary and cerebral
blood flow present during the low-flow state associated with shock.
Dopamine and dobutamine are the drugs of choice to improve
Dopamine (Intropin)- 5-20 mcg/kg/min IV continuous infusion;
increase by 1-4 mcg/kg/min q10-30min to optimal response.
Dobutamine (Dobutrex)- 5-20 mcg/kg/min IV continuous infusion.
Phosphodiesterase enzyme inhibitors- These agents improve cardiac
output in refractory hypotension and shock. Milrinone and
inamrinone (formerly amrinone) may be used.
Milrinone- Loading dose: 50 mcg/kg IV over 10 min
infusion: 0.375-0.75 mcg/kg/min IV
Inamrinone- Initial bolus: 0.75 mg/kg IV slowly over 2-3 min.
Maintenance infusion: 5-10 mcg/kg/min IV; not to exceed 10 mg/kg;
adjust dose according to response.
Platelet Aggregation Inhibitors- Agents that irreversibly inhibit
platelet aggregation may improve morbidity.
Aspirin- 160-324 mg PO or chewed;
Vasodilators- Smooth-muscle relaxers and vasodilators that can
reduce systemic vascular resistance, allowing more forward flow and
improving cardiac output.
Nitroglycerin- 10-20 mcg/min IV infusion.
Analgesics- Pain control
Diuretics- drugs cause diuresis to decrease plasma volume and
edema and thereby decrease cardiac output BP
Furosemide (Lasix)- 40-80 mg/d IV/IM
Natriuretic peptide- These drugs cause arterial and venous dilation
by binding to cyclic GMP receptor on vascular smooth muscle
causing smooth muscle relaxation.
Nesiritide- Initial 2 mcg/kg IV bolus over 30 min followed by
continuous infusion at 0.01 mcg/kg/min
Medical procedures to treat cardiogenic shock usually focus on
restoring blood flow through heart. They include:
Angioplasty and stenting. Emergency angioplasty opens blocked
coronary arteries, letting blood flow more freely to heart. Doctors
insert a long, thin tube (catheter) that's passed through an artery,
usually in leg, to a blocked artery in heart. This catheter is equipped
with a special balloon tip. Once in position, the balloon tip is briefly
inflated to open up a blocked coronary artery. At the same time, a
metal mesh stent may be inserted into the artery to keep it open
long term, restoring blood flow to the heart. Depending on
condition, doctor may opt to place a stent coated with a slowreleasing medication to help keep your artery open.
Balloon pump. Depending on condition, doctors may choose to
insert a balloon pump in the main artery of heart (aorta). The balloon
pump inflates and deflates to mimic the pumping action of your
heart, helping blood flow through.
If medications and medical procedures don't work to treat
cardiogenic shock, your doctor may recommend surgery.
Coronary artery bypass surgery. Bypass surgery involves sewing
veins or arteries in place at a site beyond a blocked or narrowed
coronary artery (bypassing the narrowed section). This restores
blood flow to the heart.
Surgery to repair an injury to your heart. Sometimes, an injury in
heart, such as a tear in one of heart's chambers or a damaged heart
valve, can cause cardiogenic shock. If an injury is causing cardiogenic
shock, doctor may recommend surgery to correct the problem.
Heart pumps. These mechanical devices, called left ventricular assist
devices (LVADs), are implanted into the abdomen and attached to a
weakened heart to help it pump. Implanted heart pumps can
significantly extend and improve the lives of some people with endstage heart failure who aren't eligible for or able to undergo heart
transplantation or are waiting for a new heart.
Heart transplant. If heart is so damaged that no other treatments
work, a heart transplant may be a last resort for treating cardiogenic