Cardiovascular Emergencies Study Guide for the CEN

General Information

Questions about this type of emergency occupy about 12.5 percent of the entire test, making it one of the four most-emphasized topics. These questions assess how well you know the cardiovascular system and the appropriate diagnostic and treatment concepts.

Acute Coronary Syndrome (ACS)

ACS is a general term that describes a sudden reduction in or blockage in blood flow to the heart, also known as myocardial ischemia. This can happen due to angina pectoris or an acute myocardial infarction.

Angina Pectoris

Angina pectoris occurs when the blood oxygen demand of the heart exceeds the supply that it is receiving, for instance, when the patient is climbing a flight of stairs. The presenting symptom is crushing or squeezing chest pain that resolves and does not result in damage to the myocardial tissue. It can be divided into two subsets:

unstable angina—This happens on an unpredictable basis and may or may not resolve easily with rest or the administration of sublingual nitroglycerin. It is more likely to progress to an acute myocardial infarction.
stable angina—This happens in predictable situations, such as when the patient exercises, and resolves rapidly with rest or the administration of sublingual nitroglycerin.

Acute Myocardial Infarction (AMI)

An AMI is a disruption in blood flow to the heart that lasts long enough to result in tissue damage. Symptoms of an AMI include:

chest pain, pressure, or discomfort
pain that radiates to the arm, abdomen, or jaw
sweating
nausea
generalized weakness or fatigue
shortness of breath
coughing up pink, frothy sputum
irregular heart beat
electrocardiogram (ECG) changes
syncope
sudden death

Be aware that AMI symptoms don’t always present with the stereotypical chest pain, especially in women. This pain can last for hours without resolution.

There are two subsets of AMIs:

non-ST-elevation myocardial infarction (NSTEMI)—This is a partial blockage in one of the coronary arteries that reduces blood flow to the heart muscle.
ST-elevation myocardial infarction (STEMI)—This is a complete blockage in one of the coronary arteries that blocks blood flow to the heart muscle and is characterized by hyperacute ECG T waves that transform to ST-elevation as tissue damage progresses.

An AMI, especially a STEMI, is a life-threatening condition that can lead to sudden death due to cardiac arrest related to a dysrhythmia. It can also lead to congestive heart failure and cardiogenic shock due to reduced cardiac output.

Assessment

The rapid assessment and identification of a patient experiencing an AMI is key to ensuring successful outcomes and timely treatment. Monitor vital signs closely and note any hypotension or arrhythmias. Watch for shortness of breath and crackles or rales in the lungs that can indicate a compromise in cardiac function. Review the symptoms that your patient is experiencing frequently, and notify the provider of any changes. An ECG should be obtained upon arrival in the emergency room, and the patient should remain on a constant cardiac monitor.

Review your ECG rhythm strips and be able to identify ST elevation, hyperacute T waves, ST depression, different types of heart blocks, and more. Angina pectoris, especially unstable or new-onset angina, needs to be treated as an AMI until proven otherwise (this will be distinguished by changes noted on the ECG).

The lab work that is commonly drawn in the case of a suspected AMI includes troponins, creatine kinase (CK), MB isoenzyme of creatine kinase (CK-MB), and myoglobin, all of which can indicate damage to the cardiac muscle. Serial troponin levels are drawn because troponin levels will elevate hours after cardiac damage has occurred. A complete blood count (CBC) will be used to rule out anemia, and a comprehensive metabolic panel (CMP) will check for any electrolyte abnormalities. A B-type natriuretic peptide (BNP) test will be performed to evaluate for the presence of congestive heart failure. A chest X-ray may be performed to check for an enlarged heart, and an echocardiogram may be performed to provide a more detailed look at the patient’s cardiac function. This may not happen in the emergency room.

Treatment

The course of treatment will be determined by the patient’s ECG and lab work, as well as their presentation of symptoms. If the patient’s oxygen saturation is below 94, they should receive titrated oxygen via nasal cannula to maintain the oxygen saturation greater than 94. IV access should be established and nitroglycerin administered, either in an intravenous form or a sublingual form. Morphine via IV push (IVP) can be used to treat pain and reduce any air hunger that the patient may be experiencing.

Antithrombotic therapy can be used to dissolve the blockage or prevent further blockages from occurring. This may take the form of anticoagulation like a heparin drip and/or an antiplatelet agent like oral aspirin. Any electrolyte abnormalities that are identified should be addressed immediately to reduce the risk of dysrhythmias.

If the ECG indicates that the patient is experiencing a STEMI, they should be transferred to the cardiac catheterization lab for percutaneous coronary intervention (PCI). This may involve a balloon angioplasty to clear the blockage and/or the placement of a cardiac stent.

The door-to-balloon rule for STEMI patients prescribes a 90-minute time frame that begins with their arrival at the ER and ends when the catheter crosses the patient’s obstructing lesion. Adhering to this time frame as closely as possible limits the amount of damage that can occur in the patient’s cardiac muscle. Following the intervention, the patient will be admitted to a critical care cardiac unit for close monitoring.

Aneurysm and Dissection

An aneurysm is a bulge or weakness in an arterial wall. It can be congenital or can result from untreated hypertension that weakens the arterial wall over time. A dissection occurs when the inner wall of the artery tears, allowing blood to separate the different layers. If the dissection penetrates to the outer wall of the artery, a life-threatening hemorrhage can occur in a matter of minutes.

Aortic Aneurysm

An aortic aneurysm is a bulge in the aorta, the largest artery in the body. The aorta is made up of five different parts: the aortic root, the ascending aorta, the aortic arch, the descending thoracic aorta, and the abdominal aorta. In many cases, the patient is asymptomatic and the aneurysm is discovered as an incidental finding on an exam that the patient undergoes for another diagnosis. Depending on the size and location of the aneurysm, surgical treatment may be required, or the healthcare provider may recommend annual monitoring.

Assessment

An aortic dissection is a life-threatening emergency. The symptoms of an aortic dissection can mimic many other cardiac-related conditions and can vary depending on the specific location of the dissection. Commonly reported symptoms include:

sudden severe upper back or chest pain that begins with a ripping sensation
sudden severe abdominal pain
leg pain
difficulty ambulating
a weak pulse in one leg
shortness of breath
loss of consciousness

Varying neurological deficits, such as one-sided weakness, sudden vision problems, or difficulty speaking, can be present in approximately one-fifth of patients and can be easily mistaken for a stroke. The best method for diagnosing an aortic aneurysm is a computed tomography (CT) scan. An echocardiogram is another option if a CT scanner is not available.

Treatment

In the case of dissection, prompt surgical treatment is the only intervention. It is your job to help ensure that the patient can remain stable until they can get to the operating room. If your facility is not equipped to deal with this kind of surgery, the patient may need to be transferred to another healthcare facility. Speed is lifesaving in this instance.

Establish multiple large-bore peripheral IVs, and be prepared to assist with a central line insertion. Expect to provide frequent transfusions of blood products and fluid resuscitation. You will also need to use vasopressors if you are unable to maintain an adequate blood pressure to perfuse vital organs. You will send off frequent CBCs and CMPs to monitor the patient’s status. The patient should remain on a constant monitor.

Cardiopulmonary Arrest

Cardiopulmonary arrest is the absence of cardiac activity or respiration necessary to sustain life. It can occur due to a wide variety of causes. The correct identification of cardiopulmonary arrest and initiation of high-quality cardiopulmonary resuscitation (CPR) can save your patient’s life.

Assessment

Assess your patient’s level of responsiveness after ensuring that the scene is safe. If they are unresponsive, check for respirations and palpate the carotid artery to check for a pulse for at least five but no more than 10 seconds (use the brachial artery in infants less than 12 months of age).

Remember that if the patient is unresponsive and you are unable to palpate a pulse, it qualifies as cardiac arrest, even if you observe a rhythm on the monitor. The patient’s heart is not beating in a rhythm that can perfuse the rest of the body. In pediatric patients, a heart rate of less than 60 bpm and signs of poor perfusions, such as weak pulses, pallor, mottling, or cyanosis, indicates that chest compressions will be necessary.

Respiratory arrest occurs when the patient is not breathing or having adequate respirations but has adequate cardiac activity to maintain perfusion.

Treatment

The primary treatment should be the initiation of high-quality CPR as soon as you have made sure that the scene is safe and verified that the patient is unresponsive. For adults, provide high-quality chest compressions and assisted respirations in a 30:2 ratio; for children, use a 15:2 ratio if two rescuers are present and 30:2 if one rescuer is present. In the case of respiratory arrest but adequate cardiac function, respirations can be provided for the patient using a bag-mask-valve (BMV) device to deliver respirations 10 to 12 times per minute.

Use the automated emergency defibrillator (AED) to analyze the patient’s cardiac rhythm and determine when to provide a shock. Continue CPR while the AED analyzes the cardiac rhythm, ensure that everyone is clear of the patient before shocking, and do not shock if the patient is lying in any water. Remember that asystole and pulseless electrical activity (PEA) are not shockable rhythms.

While providing care, you should run through the five Hs and five Ts to determine the underlying cause of the cardiopulmonary arrest.

The five Hs:

hypovolemia
hypoxia
hydrogen ion (acidosis)
hypo/hyperkalemia
hypothermia

The five Ts:

tension pneumothorax
tamponade
trauma
coronary thrombosis
pulmonary thrombosis

Treating the underlying cause can also help to restore circulation and save the patient’s life. The advanced cardiac life support (ACLS) guidelines will guide the specific treatment protocols used to treat the different causes of cardiopulmonary arrest.