Cardiogenic Shock

General

DRG Category: 292

Mean LOS: 3.9 days

Description MEDICAL Heart Failure and Shock With Complication or Comorbidity

Introduction

Cardiogenic shock occurs when cardiac output is insufficient to meet the metabolic demands of the body, resulting in inadequate tissue perfusion. It is a medical and nursing emergency. There are four stages of cardiogenic shock: initial, compensatory, progressive, and refractory.

During the initial stage, there is diminished cardiac output without any clinical symptoms. In the compensatory stage, the baroreceptors respond to the decreased cardiac output by stimulating the sympathetic nervous system to release catecholamines to improve myocardial contractility and vasoconstriction, leading to increased venous return and arterial blood pressure. Impaired renal perfusion activates the renin-angiotensin system, whose end product, angiotensin II, causes sodium and water retention as well as vasoconstriction. The progressive stage follows the compensatory stage if there is no intervention or if the intervention fails to reverse the inadequate tissue perfusion. Compensatory mechanisms, aimed at improving cardiac output and tissue perfusion, place an increased demand on an already compromised myocardium. As tissue perfusion remains inadequate, the cells begin anaerobic metabolism, leading to metabolic acidosis and fluid leakage out of the capillaries and into the interstitial spaces. A decrease in circulating volume and an increase in blood viscosity may cause clotting in the capillaries and tissue death.

As the body releases fibrinolytic agents to break down the clots, disseminated intravascular coagulation (DIC) may ensue. Lactic acidosis causes depression of the myocardium and a decrease in the vascular responsiveness to catecholamines, further reducing cardiac output. Blood pools and stagnates in the capillaries, and the continued increase in hydrostatic pressure causes fluid to leak into the interstitium. Severe cerebral ischemia causes depression of the vasomotor center and loss of sympathetic stimulation, resulting in blood pooling in the periphery, a decrease in preload, and further reduction in cardiac output. If there is no effective intervention at this point, the shock will progress to the refractory stage, when the chance of survival is extremely limited. Most experts acknowledge that cardiogenic shock is often unresponsive to treatment and has a mortality rate ranging from 20% to 50% if prompt medical intervention occurs. Complications include cardiopulmonary arrest, dysrhythmias, organ failure, stroke, and death.

Causes

The most common cause of cardiogenic shock is acute myocardial infarction (MI) resulting in a loss of more than 40% of the functional myocardium. Cardiogenic shock occurs with 5% to 10% of all hospital admissions for acute MI. Other causes include papillary muscle rupture, left ventricular free wall rupture, acute ventricular septal defect, severe congestive heart failure, end-stage cardiomyopathy, severe valvular dysfunction, acute cardiac tamponade, cardiac contusion, massive pulmonary embolus, or overdose of drugs such as beta blockers or calcium channel blockers.

Genetic Considerations

While several genetic factors may contribute to susceptibility to cardiogenic shock, no direct genetic link has been documented. Tumor necrosis factor (TNF) alpha (TNF-alpha) variants have been associated with severe heart failure. Polymorphisms in several genes may be predictors of survival: TNF-alpha, interleukin (IL) 6 (IL6), IL10, transforming growth factor (TGF) beta (TGF-beta), and interferon (IFN)-gamma (IFNG) cytokine. Individuals who carry the TNF-2 allele appear to have better outcomes than those with other variants of this gene.

Sex Life Span Considerations

Cardiogenic shock can occur at any age but is more common in middle-aged and older adults. Anyone at risk for coronary artery disease, either male or female, is also at risk for cardiogenic shock as a result of an acute MI. Older adults are at greater risk because of their diminished ability to compensate for an inadequate cardiac output and tissue perfusion; they also have the highest mortality rate (55% for people over 75 years). While the overall incidence of cardiogenic shock is higher in men than in women, the percentage of female patients with MI who develop cardiogenic shock is higher than that of male patients with MI. In cardiogenic shock after MI, women are less likely than men to receive coronary angiography, percutaneous coronary interventions, and mechanical circulatory support despite having higher rates of mortality than men.

Health Disparities Sexual/Gender Minority Health

The Centers for Disease Control and Prevention report that 11.5% of White persons, 9.5% of Black persons, 7.4% of Hispanic persons, and 6.0% of Asian persons have heart disease. Significant health disparities exist in the cardiac care of underrepresented groups as compared to White persons. Black, Indigenous, and other people of color are known to receive care less often guided by standard cardiac care guidelines than White persons. Unless patients have health insurance, White patients are more likely to receive coronary angiograms and other coronary interventions than Black and Hispanic patients. In cardiogenic shock, temporary mechanical circulatory support such as intra-aortic balloon pump, ventricular assist device, and extracorporeal membranous oxygenation is used more in White patients than in Black patients, and more often in insured patients than in Medicare, Medicaid, or uninsured patients (Thangam et al., 2020). Black, Indigenous, and other people of color are also less likely to be referred to cardiologists and cardiac surgeons than White persons (Batchelor et al., 2019). In cardiogenic shock following MI, hospital-level disparities exist in the management and outcomes. Admissions to urban hospitals have better outcomes and earlier use of technology than admissions to rural hospitals.

Transgender is a term used to describe persons whose gender identity is different from their sex assigned at birth. Approximately 1% of the U.S. population identify themselves as transgender. Sexual and gender minority persons have higher odds for multiple chronic conditions, cancer, and poor quality of life and are more apt to have disabilities than cisgender males and females (cisgender is a term used to describe persons whose gender identity and gender expression are aligned with their assigned sex listed on their birth certificate). Gender-affirming hormone therapy is the use of hormone therapy for gender transition or gender affirmation and can be masculinizing or feminizing. It may also affect cardiovascular health in transgender females. In a large sample, researchers have found that transgender men and women are more likely to be overweight than cisgender women. Compared to cisgender women, transgender women reported higher rates of diabetes, angina/coronary disease, and MI. Gender-nonconforming men and women reported higher odds of MI than cisgender women. Transgender women also had higher rates of any cardiovascular disease than cisgender men (Cacerese, Jackman, et al., 2020).

Global Health Considerations

European countries have a prevalence of cardiogenic shock similar to that of the United States. For unknown reasons, Asian/Pacific Islanders have a higher incidence of cardiogenic shock than do other groups. No data are available for developing countries.

Assessment

History

Cardiogenic shock often occurs after a patient has been admitted to the hospital following an acute MI. The patient is likely to have a history of symptoms of an acute MI, including crushing, viselike chest pain or heaviness that radiates to the arms, neck, or jaw; lasts more than 20 minutes; and is unrelieved by nitroglycerin and rest. Other MI symptoms include shortness of breath, nausea, vomiting, sweating, anxiety, and a sense of impending doom. Determine if the patient has a history of cardiac disease or previous MI, use of cocaine, hypertension, cigarette smoking, or a family history of cardiac disease.

Physical Examination

The most common symptoms are hypotension in the absence of hypovolemia as well as oliguria, cyanosis, cool extremities, and reduced mental status. During the initial stage of shock, there are no clinical findings unless the cardiac output can be measured. When the patient has entered the compensatory stage, symptoms may include an altered level of consciousness; sinus tachycardia; the presence of an S₃ or S₄ gallop rhythm; jugular venous distention; hypotension; rapid, deep respirations; pulmonary crackles; venous oxygen saturation (SvO₂) less than 60%; cyanosis; urine output less than 20 mL/hour; decreased urinary sodium; increased urinary osmolarity; peripheral edema; hyperglycemia; hypernatremia; cold, clammy skin; and decreased bowel sounds.

As the patient enters the progressive stage, the symptoms become more pronounced and resistant to treatment. The patient becomes mentally unresponsive; hypotension becomes worse, requiring high doses of positive inotropic agents; metabolic and respiratory acidosis become apparent; oliguria or anuria and anasarca may ensue; and symptoms of DIC may be present. The patient’s skin may appear mottled, cyanotic, and ashen with faint peripheral pulses and cold extremities. When the shock reaches the refractory stage, multisystem organ failure is apparent, with the above symptoms unresponsive to treatment.

Psychosocial

The patient in cardiogenic shock is in a life-threatening situation. The chances for survival are reduced, and the patient may experience a sense of impending doom. The impaired tissue perfusion may lead to anxiety and fear. The patient and the patient’s family or significant other may be in crisis. Both the patient and the family may be experiencing grief in response to the potential loss of life and need significant emotional support.

Diagnostic Highlights

Test	Normal Result	Abnormality With Condition	Explanation
Hemodynamic monitoring	Right atrial pressure (RAP): 1-8 mm Hg; pulmonary artery occlusion pressure (PAOP): 4-12 mm Hg; cardiac output (CO): 4-7 L/min; cardiac index (CI): 2.5-4 L/min/m²; systemic vascular resistance (SVR): 800-1,200 dynes/sec per cm⁻⁵	RAP: > 6 mm Hg; PAOP: > 18 mm Hg; CO: < 5 L/min; CI: < 2.2 L/min/m²; SVR: >1,200 dynes/sec per cm⁻⁵	Elevated filling pressures in heart and low systolic blood pressure occur in the setting of low cardiac output; arterial constriction occurs as a compensatory mechanism. Hemodynamic monitoring with serial measures of cardiac output is important in the diagnosis of cardiogenic shock.

Other Tests: Compete blood count, serum chemistry tests, electrocardiogram, echocardiogram, transesophageal echocardiography, coronary angiography, cardiac enzymes, lactate levels, troponin T and I levels, arterial blood gases, brain natriuretic peptide, urinalysis, and coagulation studies

Primary Nursing Diagnosis

Diagnosis: Decreased cardiac output related to inadequate cardiac contractility as evidenced by hypotension, oliguria, cyanosis, and/or decreased mental status

Outcomes: Circulation status; Cardiac pump effectiveness; Tissue perfusion: Cardiopulmonary, cerebral, abdominal organs, peripheral; Vital signs

Interventions: Cardiac care; Emergency care; Vital signs monitoring; Oxygen therapy; Fluid/electrolyte management; Fluid monitoring; Shock management: Volume and cardiac, Medication administration; Resuscitation; Surveillance

Planning and Implementation

Collaborative

Cardiogenic shock is an emergency because of an unstable cardiovascular system that requires immediate intervention to reverse shock before vital organs are damaged. The primary goal in treating cardiogenic shock is to improve tissue perfusion and oxygenation with rapid diagnosis, maintenance of blood pressure and cardiac output with vasoactive medications, and support for airway and breathing. These goals generally are accomplished by coronary reperfusion with medications and percutaneous coronary intervention (coronary angioplasty), or coronary artery bypass surgery within the first 90 minutes after arrival at the hospital. To limit the infarct size and treat the dyspnea, pulmonary congestion, hypoxemia, and acidosis, the physician is likely to prescribe oxygen, intubation, and mechanical ventilation. Further trials are now in progress to determine the role of mechanical circulatory devices such as intra-aortic balloon pulsation, percutaneous mechanical circulatory devices, and extracorporeal membrane oxygenation.

Pharmacologic Highlights:

General Comments: Improving cardiac output, which is necessary to improve tissue perfusion, can be accomplished in several ways. If the patient is able to maintain hemodynamic stability, the physician prescribes medications, namely diuretics and nitrates, to reduce preload. Generally, the patient may be too hypotensive to tolerate the vasodilative effects of both diuretics and nitrates. The patient needs improvement in myocardial contractility without adding significant workload on the heart. Dopamine may also be used in an attempt to improve contractility and cardiac output. Other vasoactive drugs, such as milrinone or inamrinone, may also be used to increase contractility. Vasopressors may be used in an attempt to increase the mean arterial blood pressure to a level that provides adequate tissue perfusion (> 70 mm Hg). Several agents that may be administered include dopamine, epinephrine, norepinephrine, and phenylephrine hydrochloride. Antiplatelet agents may also be administered to reduce clotting and opioid analgesics to reduce pain and stress.

Medication or Drug Class	Dosage	Description	Rationale
Dobutamine if the systolic blood pressure is > 80 mm Hg (dopamine is the drug of choice for hypotensive patients)	2-40 mcg/kg/min (but usually in the range of 2-20 mcg/kg/min); milrinone may be added if patients are not responding or are developing tachycardia in response to dobutamine	Sympathomimetic	Dobutamine improves heart contractility without much effect on heart rate; renal function may also improve through increased cardiac output and renal perfusion
Nitroglycerine	Begin at 5 mcg/min and increase by 5 mcg/min every 3-5 min	Vasodilator	Relax vascular smooth muscle and reduce systemic vascular resistance, thereby increasing cardiac output
Diuretics	Varies by drug	Loop diuretics (preload) diuretics	Reduce venous return

Independent

Patients with cardiogenic shock experience a life-threatening condition that results in multiple complex needs, rapid decision making, and a rapid emergency response. Supporting tissue perfusion and limiting myocardial oxygen consumption are primary concerns. Decreasing oxygen demand may limit ischemia, injury, and infarction. Position the patient to maximize circulation to vital organs. Restrict the patient’s activity, and maintain the patient on bedrest. Address the patient’s anxiety by explaining all procedures. Permit the family or significant others to remain with the patient as long as their presence does not cause added stress. Maintaining a calm and peaceful environment provides reassurance and reduces anxiety, which in turn reduces myocardial oxygen consumption. Serial vital signs, ongoing surveillance, regular communication with the critical care team, and careful oversight of vasoactive medications are core nursing responsibilities.

Restricted activity could lead to impaired skin integrity, necessitating frequent assessment and care of the skin. Adequate protein and calories are essential for the prevention or healing of impaired skin integrity and should be provided by oral, enteral, or parenteral means.

Evidence Based Practice Health Policy

Vallabhajosyula, S., Dunlay, S., Barsness, G., Rihal, C., Holmes, D., & Prasad, A. (2019). Hospital-level disparities in the outcomes of acute myocardial infarction with cardiogenic shock. American Journal of Cardiology, 124, 491-498. [PMID:31221462]

The authors explore whether treatment and outcomes for patients with cardiogenic shock were affected by hospital type (teaching/nonteaching), size (small/large), and location (urban/rural). They examined a large, retrospective cohort of adult admissions from the National Inpatient Sample database during 2000 to 2014 (N = 362,065) with a primary diagnosis of acute MI with cardiac tamponade.
Lower mortality rates were noted among urban nonteaching and urban teaching hospitals as compared with rural hospitals, and lower mortality rates were noted in large hospitals as compared with smaller hospitals. Large and urban hospitals made greater use of early coronary angiography, percutaneous cardiac intervention, and mechanical circulatory support. The authors concluded that the hospital-level disparities in the management and outcomes of acute MI with cardiogenic shock cannot be fully accounted for by differences in patient characteristics, indicating disparities for patients in smaller and rural hospitals.

Documentation Guidelines

Physical findings: Cardiopulmonary, renal, neurological, and integumentary systems; skin integrity
Hemodynamic response to inotropic medications, diuretics, nitrates, mechanical circulatory devices, and oxygen
Presence of complications: Pulmonary congestion, respiratory distress, unrelieved chest pain, wound infection, thromboses or emboli, and skin breakdown
Reaction to the crisis and prognosis

Discharge and Home Healthcare Guidelines

The patient will likely require extensive rehabilitation after a critical illness. Teach the patient how to reduce controllable risk factors for heart disease. Be sure the patient understands the medication prescribed. Discuss smoking cessation programs and support systems.

RECURRENCE OF CHEST PAIN Teach the patient to call 911 for any chest pain that is not relieved by rest and/or nitroglycerin. Instruct the patient not to ignore the pain or wait to call for assistance.

RECURRENCE OF HEART FAILURE Teach the patient to restrict fluids to 2 to 2.5 L per day or as prescribed by the physician and to observe sodium restrictions. The patient should report a weight gain of greater than 4 pounds in 2 days to the physician. Finally, teach the patient to monitor for increasing shortness of breath and edema and to report either of those signs or symptoms to the physician. If the patient experiences acute shortness of breath, the patient should call 911 or go to the emergency department immediately.