Introduction

As defined by the American Heart Association and the American College of Cardiology, "(sudden) cardiac arrest is the sudden cessation of cardiac activity so that the victim becomes unresponsive, with no normal breathing and no signs of circulation. If corrective measures are not taken rapidly, this condition progresses to sudden death. Cardiac arrest should be used to signify an event as described above, that is reversed, usually by CPR and/or defibrillation or cardioversion, or cardiac pacing. Sudden cardiac death should not be used to describe events that are not fatal."[1] Each year, more than 400,000 Americans succumb to sudden cardiac death.[2] Those experiencing cardiac arrest may or may not have been previously diagnosed with heart disease. The cause of cardiac arrest varies by population and age, most commonly occurring in those with a previous diagnosis of heart disease. Most cardiac deaths are sudden and usually unexpected, which has proven to be uniformly fatal in the past. However, bystander cardiopulmonary resuscitation (CPR) and advances within emergency medical services (EMS) have proven life-saving interventions. Despite this, approximately 10% of those suffering from cardiac arrest leave the hospital alive, most of whom are neurologically impaired.[3]

Etiology

Cardiac arrest is usually due to underlying structural cardiac disease. Seventy percent of cardiac arrest cases are thought to be due to ischemic coronary disease, the leading cause of cardiac arrest.[2] Other structural causes include congestive heart failure, left ventricular hypertrophy, congenital coronary artery abnormalities, arrhythmogenic right ventricular dysplasia, hypertrophic obstructive cardiomyopathy, and cardiac tamponade. Nonstructural cardiac causes include Brugada syndrome, Wolf-Parkinson-White syndrome, and congenital long QT syndrome. There are many non-cardiac etiologies, including intracranial hemorrhage, pulmonary embolism, pneumothorax, primary respiratory arrest, toxic ingestions, including drug overdose, electrolyte abnormalities, severe infection (sepsis), hypothermia, or trauma.

Epidemiology

Occlusive (ischemic) coronary disease is the leading cause of cardiac arrest and sudden cardiac death.[4] An initial peak of sudden death occurs from birth to 6 months of age, due to sudden infant death syndrome. Incidence is typically very low until reaching a second peak between the ages of 45 and 75. Interestingly, the most common cause of cardiac death seen in adolescents and young adults mirrors that of middle-aged and older adults.[5] Within the United States, up to 70% of all sudden cardiac death is due to underlying coronary heart disease.[2] The incidence of cardiac death is lower for women at a younger age when compared to males.[6] Despite the lower risk for women, risk factors for occlusive heart disease, such as hypertension, hyperlipidemia, diabetes, cigarette smoking, increasing age, and family history of coronary disease, continue to predispose women to cardiac death, as in males.[6]

History and Physical

In many patients, warning symptoms may precede a cardiac arrest. However, these symptoms are often unrecognized or ignored by the individual.[7] Many patients who survive cardiac arrest have amnesia, not allowing for the recollection of symptoms before an event. Data obtained from those who did not have amnesia, from family members, and/or from those who witnessed the event show that the most common symptom was chest pain.[7] Appropriately, this mirrors the most common presentations of acute coronary ischemia. An individual found to be in cardiac arrest, unresponsive, without a pulse, and not breathing. A quick head-to-toe assessment helps guide treatment.

Evaluation

While treating a patient in cardiac arrest, little to no blood or imaging testing is necessary. If one can obtain point-of-care testing, a potassium and glucose level may be beneficial. Point-of-care ultrasound to look for cardiac activity may also be beneficial if it does not interfere with resuscitation efforts.[8]

Treatment / Management

A patient in cardiac arrest is treated in multiple stages. The interventions that have proven to reverse cardiac arrest include early CPR and early defibrillation. The initial step involves identification and basic life-support measures. If public-access defibrillation is available, it should be activated and used if needed. Next, advanced life support measures are initiated, including intravenous or intraosseous medication administration. If return of spontaneous circulation (ROSC) is obtained, the patient undergoes post-resuscitation care with subsequent long-term management. Identification of a cardiac arrest victim includes assuring that the patient is unresponsive, without central pulses, and not breathing normally. Once a victim is identified, immediate CPR and activation of the emergency response system should be a priority. More recently, public-access defibrillation has added another layer to the response. Treatment of cardiac arrest depends on the rescuer's scope of practice.

Lay Rescuer

Treatment includes hands-only CPR and utilization of an AED, if available.[9][10] If a patient has had a drowning episode, they can attempt 2 rescue breaths, since the cause of cardiac arrest is likely from a primary respiratory arrest. If there is no response to rescue breathing, CPR should be initiated. One should continue CPR until emergency responders arrive.

Basic Life Support

Treatment for those certified in basic life support (BLS) includes the above, with the addition of ventilation during active CPR. Current guidelines recommend 2 breaths for every 30 compressions (30:2).[9] Providers can also manipulate the airway to improve patency, thereby allowing proper ventilation. These maneuvers include the head tilt, chin lift, and jaw thrust.[11][12] Oral airway adjuncts, including the oral pharyngeal airway (OPA) and the nasopharyngeal airway (NPA), should also be utilized to benefit ventilation.

Advanced Life Support

Providers can use BLS treatment with the addition of medications and advanced airways, including supraglottic airway devices (King LT, Igel) and endotracheal intubation. Medicines used in cardiac arrest include Epinephrine and Amiodarone. Advanced life support (ALS) providers have the added benefit of cardiac rhythm interpretation, enabling quicker defibrillation if indicated. Advanced Cardiac Life Support (ACLS) can teach providers the algorithms used to resuscitate a patient in cardiac arrest.

Physician

Providers can use ALS treatment and progress to a wide scope of practice, dependent on medical versus traumatic etiology. 

Medical

Medical cardiac arrest patients are treated with ALS as discussed above. These patients can also be placed on extracorporeal membrane oxygenation (ECMO).[13] This allows for oxygenation of the victim's blood supply until the cardiac function is restored.

Trauma

Trauma patients can be divided into blunt (motor vehicle accident) versus penetrating (gunshot wound). Blunt traumatic arrests are usually secondary to a significant vessel injury. Patients usually succumb to their injuries immediately after the event takes place. Most blunt trauma arrest patients are deemed to be futile upon arrival of first responders. Victims of penetrating trauma are more likely to survive when compared to those with blunt traumatic injuries.[14] Penetrating trauma patients are typically treated with bilateral needle decompressions. If ROSC is not obtained, and if, within a non-futile time frame, patients can undergo a resuscitative thoracotomy. This allows direct visualization and, if needed, intervention on the heart, lungs, and large vessels.[14] Another technique that is still under evaluation is resuscitative endovascular balloon occlusion of the aorta (REBOA).[15] This involves placing an endovascular balloon in the aorta to control hemorrhage, similar to cross-clamping the aorta, which is a manual technique used during a resuscitative thoracotomy.

Differential Diagnosis

Syncope is a temporary loss of consciousness that is usually caused by decreased blood flow to the brain. Patients who experience syncope are transiently unresponsive, as are all individuals experiencing cardiac arrest. However, patients who are in cardiac arrest do not have a normal breathing pattern or a pulse, differentiating syncope from cardiac arrest. A seizure can also be mistaken for cardiac arrest. Patients having a seizure are unresponsive and probably have abnormal respirations. Abnormal rhythmic activity and the presence of a pulse differentiate a seizure from cardiac arrest. Overdose, particularly from opiates, can lead to a patient who is unresponsive and not breathing normally. The presence of a pulse differentiates an opiate overdose from cardiac arrest.

Prognosis

Factors that are proven to improve survivability include witnessed cardiac arrest with immediate CPR and utilization of defibrillation when indicated.[16] Young and healthy patients are more likely to obtain ROSC compared to older adults and those who have more comorbidities. Those who are victims of penetrating trauma have an increased chance of survival compared to those who are victims of blunt traumatic arrest. Studies have not shown proven benefit for ALS level of care in cardiac arrest, including endotracheal intubation and intravenous (IV) medication administration.[17]

Complications

Numerous complications can occur during a cardiac arrest. Although not common, the most detrimental complication for a patient in a shockable rhythm is AED failure. Other complications include the inability to obtain IV/IO access. After ROSC, failing to secure and/ or maintain a definitive airway device could lead to a secondary cardiac arrest. During a traumatic etiology, malposition of needle thoracotomy or pericardiocentesis also leads to complications.

Postoperative and Rehabilitation Care

If ROSC is achieved, a decision should be made regarding targeted temperature management. Candidates for targeted temperature management include those with a medical etiology who are unresponsive and stable. Targeted temperature management has been shown to improve mortality and neurological outcomes in patients who have survived a medical cardiac arrest.[18] After the patient stabilizes from their cardiac event, the patient’s respiratory status is assessed. If the patient cannot be successfully extubated, a tracheostomy can be placed to maintain a patent airway. A percutaneous endoscopic gastrostomy (PEG) tube is commonly placed to provide nutrition. Patients who require a tracheostomy and PEG tube placement usually have a prolonged recovery time. These individuals are placed in long-term acute care (LTAC) facilities for care and rehabilitation. Patients who are successfully extubated still endure a prolonged recovery; however, they are usually more functional.

Consultations

If a cardiac arrest is due to traumatic etiology, trauma surgery is usually consulted to aid with resuscitation, including resuscitative thoracotomy. If ROSC is obtained after a medical cardiac arrest, the emergency department physician calls upon the intensive care team to take care of the patient. If the medical cardiac arrest is deemed secondary to a primary cardiac etiology, cardiology should be consulted to determine the appropriate intervention.

Deterrence and Patient Education

Most cardiac arrests occur in an out-of-hospital setting. Since immediate CPR and the use of the AED are the 2 main interventions shown to improve patient outcomes, one can see why training laypersons in adequate CPR skills can be life-saving.[19][20] Despite training, there remains hesitancy to initiate lay rescuer CPR.[19] This could be due to a lack of cardiac arrest recognition, a lack of encouragement, or a lack of confidence. The patient may also be unreachable or unmovable by the lay rescuer, hindering optimal performance.

Pearls and Other Issues

In hopes of potentially delaying cardiac arrest in the general population, one can undergo risk stratification to identify those who may benefit from interventions, including a stress test and a screening ECG. Clinicians should educate the patient about the benefits of Daily exercise, a healthy diet, effective treatment for hypercholesterolemia, hypertension, and diabetes, and smoking cessation.[20][21] Patients with post-myocardial infarction and who have been diagnosed with congestive heart failure can benefit from medication-specific medication adjustment, including the addition of beta blockers and angiotensin-converting enzyme inhibitors. Select patients can also benefit from ICD implantation.

Enhancing Healthcare Team Outcomes

The majority of patients who have cardiac arrest have underlying coronary artery disease. Alteration of modifiable risk factors and medication adjustment can delay the onset of coronary heart disease, potentially delaying cardiac arrest. Despite the many treatments available for cardiac arrest, the majority of patients have a poor prognosis. However, many lives can still be saved with the basic, most important interventions, including defibrillation and bystander CPR. Promotion of such education to loved ones and others interested can be lifesaving.

All clinicians who see patients should be familiar with the basic principles of resuscitation of a patient who has just arrested. In the hospital, resuscitation is carried out by an interprofessional team that attends all cardiac arrest events. Outside the hospital, resuscitation may be performed by the public or a healthcare worker. In each case, there must be someone in charge overseeing the resuscitation process. In the hospital, nurses are responsible for bringing the equipment to the patient's room and documenting the event. In all cases, everyone has an assigned role so that resuscitation can be undertaken without delay. Unfortunately, despite optimal resuscitation, most patients have a poor outcome or do not make it. Those who survive a near-fatal arrest are monitored in the ICU. In hopes of potentially delaying cardiac arrest in the general population, one can undergo risk stratification to identify those who may benefit from interventions, including a stress test and a screening ECG.

Clinicians should educate the patient about the benefits of daily exercise, a healthy diet, and effective treatment of conditions such as hypercholesterolemia, hypertension, and diabetes, as well as smoking cessation.[20][21] Patients with post-myocardial infarction and who have been diagnosed with congestive heart failure can benefit from medication-specific adjustment, including the addition of beta-blockers and angiotensin-converting enzyme inhibitors. Select patients can also benefit from ICD implantation.

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Disclosure: Kevin Patel declares no relevant financial relationships with ineligible companies.

Disclosure: John Hipskind declares no relevant financial relationships with ineligible companies.