What Is Cardiac Shock?
Cardiac shock, or cardiogenic shock, is even more dangerous than it sounds. Most often caused by a heart attack, cardiac shock is a life-threatening emergency requiring prompt recognition and treatment.
“Cardiogenic shock is the situation where the heart is not pumping enough blood to the body,” says Dr. Mark Pool, a cardiothoracic surgeon with Texas Health Presbyterian Hospital Dallas. “‘Shock’ simply refers to inadequate blood flow to the body organs.”
That lack of blood flow can cause irreparable harm to those organs. “It’s possible to damage the kidneys in a way where the person has to go on dialysis,” Pool says. “If the blood pressure is low for long enough and severely enough, it can actually kill the person.
In cardiac shock, the heart isn’t pumping effectively (not to be confused with cardiac arrest, where the heart stops completely). Low blood pressure is a hallmark sign of cardiac shock. As the patient or bystander, you might notice the types of symptoms that would alert you to the possibility of a heart attack, plus a few specific to cardiac shock:Rapid breathing and shortness of breath.
Low blood pressure, with a systolic (top) number of less than 90 mmHg, for at least 30 minutes.
Clamminess and sweatiness.
Pale skin or mucous membranes (inside the mouth or lining of the eyes).
Chest pain or pressure.
Loss of consciousness.
Cold feet or hands.
Large veins in neck bulging.
“Heart attack pain is often experienced somewhere below your nose and above your belly button,” says Dr. Wayne Batchelor, director of the interventional cardiology program at the Inova Heart and Vascular Institute in Falls Church, Virginia. “It’s usually in the chest, and usually a severe pressure, heaviness or ache that’s relentless, often accompanied by sweating and sometimes nausea and vomiting. But it almost always lasts for more than 20 or 30 minutes.”
Persistent, severe chest discomfort, as well as upper abdominal, lower jaw or arm discomfort that’s “unrelenting, unusual, severe and often associated with sweating that doesn’t go away in 20 minutes would be a reason for concern,” Batchelor says. “Those patients should seek medical attention immediately.”
These figures can help put cardiac shock into perspective:”People don’t realize how many people die with a heart attack and it’s because of cardiogenic shock,” says Dr. Patricia Best, an interventional cardiologist and researcher at Mayo Clinic in Rochester, Minnesota. In fact, it’s the most common reason for heart attack deaths in hospitals, adds Best, who is also an associate professor of medicine and cardiovascular diseases at Mayo Clinic College of Medicine and Science. For example, of hospitalized patients treated for heart attacks, cardiogenic shock was the top cause of death by far in the 30-day follow-up period, in a study from Denmark in the Journal of the American College of Cardiology.
Among patients treated specifically for cardiac shock, death rates while still hospitalized ranged between 40% and 60% among U.S. inpatients from 2004 to 2011, according to a study in the Journal of the American Heart Association. If left untreated, the emergency condition has an even higher mortality rate.
Immediate Treatment en Route
The longer cardiogenic shock goes on, the more damage can occur to heart, brain, kidneys and bowels. Time is of the essence, starting before a patient even reaches the hospital.
“EMTs are going to check vital signs immediately,” Pool says. “One of the first things they’re trained to do: If the blood pressure is low, they’ll put in an IV and give IV fluids. That tends to increase the circulating blood volume and can help raise the blood pressure. That’s actually a sign of cardiogenic shock if the blood pressure stays low even after fluids are given.”
As EMTs continue to monitor the situation, they’ll like give the patient an aspirin to prevent clotting and blockages within blood vessels, Pool says. “They’ll rush the patient to the nearest facility with advanced heart care in order to figure out what’s going on.”
“Cardiogenic shock can be due to a large heart attack,” Batchelor says. “It can be due to a smaller heart attack in a patient with a previously damaged heart.” In some scenarios, he adds, “patients with chronically depressed heart function or decreased heart function can sometimes get cardiogenic shock without a heart attack.”
Inflammation of the heart muscle, or myocarditis, can sometimes lead to cardiac shock. Endocarditis, which is an infection of the inner lining of the heart valves, is another potential cause.
A temporary condition known as stress-induced broken heart syndrome (also called takotsubo or stress-induced cardiomyopathy), is a weakening of the heart muscle which usually resolves on its own. However, it can lead to cardiogenic shock as a complication in rare instances.
Detection and Diagnosis
“Cardiogenic shock is going to be diagnosed first by the history and physical examination,” Best says. Heart attack symptoms, a history of heart disease like heart failure, low blood pressure, rapid pulse, cold and clammy skin and signs that a patient is not thinking clearly would all raise red flags.
“And then, from our standpoint, other things that would go into it would be what we call end-organ perfusion problems, where they’re running into failure of other organs,” Best says. For instance, high levels of lactate – a waste product in the blood – can be a marker for cardiac shock.
“If you’re not eliminating the lactate, it tells you that you’re building up waste that your body isn’t taking care of,” Best says. That could indicate bowel ischemia, she says, in which there’s not enough blood flow to the bowels and lactate waste builds up.
Diagnostic tests for cardiac shock can include:Blood tests for heart, kidney and liver function.
Blood gas tests to measure oxygen and carbon dioxide levels in the arteries and veins.
Coronary angiogram using X-ray imaging and contrast dye to reveal blockages in heart arteries.
CT scan of the heart to identify heart disease or evaluate heart valve problems.
Chest X-ray to assess the heart and lungs.
Echocardiogram to examine the heart’s blood flow.
Electrocardiogram, or EKG, to detect abnormal heart rhythms and confirm a heart attack.
Pulmonary capillary wedge pressure measurement, which is invasive testing done with a thin tube called a Swan-Ganz catheter to evaluate blood flow and pressures of the heart.
The EKG tracing shows electrical wave forms, which change when the heart isn’t working correctly. There are two main kinds of heart attacks, which are defined by their EKG waves:
STEMI (ST-segment-elevation myocardial infarction). STEMIs involve total or almost total blockage of a coronary artery. This type of heart attack in particular increases the risk for developing cardiogenic shock.
NSTEMI or non-STEMI. This less severe form of heart attack, which involves only partial coronary artery blockage, typically causes less heart damage.
“The earlier you catch someone going into shock or at risk for shock, the more you can start to treat the underlying problem to help keep them out of shock,” Best says. “For someone who’s just early and at risk, we watch for signs and we would be treating with medications and doing our best to reverse the underlying cause.”
With a heart attack, the focus is on getting the blood vessel open, she says. If congestive heart failure is the problem, treatment includes alleviating the excess fluid so that the heart can function better.
In cases where dangerously low blood pressure persists, medications to constrict the blood vessels – called vasopressors – may be given to increase the blood pressure.
Cardiac shock can come on extremely quickly. “In some cases of cardiogenic shock, you can have someone who’s basically normal in the morning,” Batchelor says. “If they have a very large heart attack due to an obstruction – acute blockage of a critical artery in the heart – they can go into cardiac shock literally within minutes to hours.”
- Heart catheterization. Percutaneous cardiac intervention is a nonsurgical procedure used to open blocked coronary blood vessels. Doctors may implant a small mesh tube called a stent as part of PCI to prevent a coronary artery from re-narrowing.
- Coronary artery bypass grafting. Some patients with severe cardiac shock undergo emergency CABG surgery to improve blood flow to the heart.
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Mechanical devices can help your body avoid organ damage by assisting or restoring blood flow. Cardiogenic shock treatment may include the following heart devices:
- Impella. A fairly recent innovation, the Impella Ventricular Support System is a small, temporary implant that’s inserted by a catheter into the left side of the heart. It helps pump blood when the heart’s major pumping chamber, the left ventricle, isn’t functioning properly.
- ECMO. Similar to heart-lung machines used for open-heart surgery, extracorporeal membrane oxygenation, or ECMO, replaces heart and lung function by pumping and supplying oxygen to the patient’s blood from outside his or her body. ECMO treatment, which may last for several days, can only be received on a critical care unit.
- LVAD. A left ventricular assist device, or LVAD, is a mechanical heart pump implanted in the body. The device attaches to an outside power module through a tube. Patients can stay on LVADs indefinitely or use them as a bridge while awaiting a heart transplant, for which some patients with severe underlying heart disease may become candidates.
In 2017, the Inova Heart and Vascular Institute put together a shock task force to study best practices and state-of-the-art care for cardiac shock. “We came up with a protocol that really made a huge difference across our five-hospital institution and the 40 or so hospitals that refer to us for cardiogenic shock,” Batchelor says,
Early recognition is the basis of this treatment algorithm. “We encourage all doctors to really think about cardiogenic shock as a diagnosis as soon as possible,” says Batchelor, who was senior author of an article detailing this systematic, comprehensive approach in the November 2020 issue of the journal JACC: Heart Failure.
“A critical part of intervention strategy was activating a shock team,” Batchelor says. “Through a single call to our hospital, we can activate and get on the line interventional cardiologists, heart failure cardiologists and a critical care physician.”
This ability to access physicians both from within and outside the hospital to help “manage a patient who’s crashing and burning – through one single phone call to get immediate expertise on the line and decisions rendered early – can really make a difference,” Batchelor says.
The institute has seen significantly improved results. “We saw a mortality rate that was about 50% for cardiogenic shock drop to about 25%,” Batchelor says. “In other words, three-quarters of patients were surviving after we implemented this system,” he says, adding that many other heart centers are now adopting a similar approach.
If you or a loved one is experiencing heart-related symptoms, the top priority is getting to the nearest facility that can provide emergency care. That facility can refer you to a major heart center if indicated.
Today, however, evidence suggests that patients with cardiac symptoms may hesitate to go to the hospital because they fear COVID-19 infection. “It’s important to continue to seek medical care because things like heart attacks are still happening,” Best emphasizes. “And when people present late they’re more likely to be in cardiogenic shock and more likely to die from that heart attack.”
“Heart disease is still the No.1 killer of Americans, and it’s not waiting in quarantine,” is the message on the SecondsCount website of the Society for Cardiovascular Angiography and Interventions.
Patients hesitating to call 911 or visit the emergency room represent an indirect pandemic effect. But COVID-19 itself can also have a direct, weakening effect on the heart muscle. “It’s not very common but when it occurs it can be very serious – and there are a number of patients that are left with longstanding heart damage as a result of having COVID-19 infection,” Batchelor says.
Patients can and do get better after cardiac shock. “Someone can come in having a heart attack and be in shock at the time of their heart attack, and if you get the blood vessel open quickly and treat their shock appropriately they can recover quite significantly,” Best says.
As patients are discharged and continue to mend from cardiac shock, taking advantage of a nearby cardiac rehab program can enhance their recovery. Cardiac rehab treats (although it doesn’t cure) the patient’s underlying heart condition, Best explains. “It’s helping to bring them back to a better quality of life, putting in exercise as a component to basically help them build their heart back and be healthier.”[
The best way to prevent cardiac shock is to reduce your risk factors for heart disease in general. “The No. 1 message for smokers is stop smoking for your cardiac health,” Pool says. “Smoking is actively harming your heart, and increasing your risk of a heart attack and death.”
Heart disease prevention also includes following a healthy diet, exercising and managing high blood pressure, diabetes and stress. Genetics is pretty much the only risk factor that you can’t modify for the better, Pool says.
“Almost everything else you can at least impact with healthy choices: diet, exercise and the like,” Pool says. “You can help yourself by attending to these matters for your health, and hopefully never be in the position of having a heart attack complicated by cardiogenic shock.”