Cardiovascular Emergencies Study Guide for the CEN

Peripheral Vascular and Arterial Disease

Peripheral vascular disease is a broad term that describes impaired blood flow in any vessel returning blood to your heart. By contrast, peripheral arterial disease describes impaired blood flow in any vessel leading away from the heart. These conditions are most common in the lower extremities, but can occur anywhere in the body outside of the heart. When it affects the kidneys, it can also lead to hypertension that contributes to further kidney damage over time.

Assessment

The most common symptom is a cramping pain in the lower legs known as claudication that worsens with activity (increased blood demand) and resolves promptly with rest. Impaired circulation may cause discoloration in the feet, causing them to appear pale or dusky. Chronic wounds or open sores are also common. In severe cases, the patient may have one or more gangrenous toes, possibly even a portion of their foot. Peripheral pulses will be faint or will not be able to be palpated, potentially requiring the use of a Doppler test to hear. They may be absent altogether in severe cases.

The simplest diagnostic test is the noninvasive ankle brachial index that compares the blood pressure in the patient’s arms and legs to check for a decrease in blood pressure, which indicates impaired circulation. Other diagnostic tests include Doppler ultrasound studies, CT angiogram, and magnetic resonance angiogram.

Treatment

If an acute arterial occlusion has occurred, immediate surgical intervention is necessary to restore blood flow to the affected extremity and prevent limb loss. This will likely involve a balloon angioplasty and/or the placement of a stent to clear the blockage, as well as the initiation of anticoagulant therapy. Bypass surgery can be considered if the angioplasty or stent placement is unsuccessful.

The first line of treatment in less severe cases is medication and lifestyle changes. Medications include antiplatelet agents, cholesterol-lowering medications, and medications to treat high blood pressure. Efforts should be made to control diabetes and follow a heart-healthy diet (low fat, low sodium). Smoking cessation should be heavily encouraged if the patient still smokes tobacco. Exercise is encouraged, although the patient should stop and rest if it exacerbates their symptoms, then resume the activity when their symptoms have resolved.

Thromboembolic Disease

Thromboembolic disease describes the formation of a blood clot (thrombus) in a blood vessel anywhere in the body. The most common type is a deep vein thrombosis (DVT), which forms in a deep vein, most commonly in the leg. A pulmonary embolism (PE) describes a blood clot that forms in the lungs, either spontaneously or after breaking off from a DVT and traveling to the lungs. A thrombus can break off and travel anywhere in the body, making it possible for it to cause a stroke or myocardial infarction.

Assessment

A DVT can sometimes be asymptomatic, but common symptoms include:

• leg pain
• swelling
• warm sensation in the leg
• redness/purple discoloration in the leg

It is diagnosed through a noninvasive duplex ultrasound, magnetic resonance imaging (MRI), most commonly used for a DVT in the abdomen, and a D-dimer lab test to check for protein released by the thrombus.

Symptoms of a PE include:

• sudden shortness of breath
• chest pain that worsens with breathing or coughing
• dizziness
• tachypnea
• tachycardia
• productive cough with bloody sputum

PEs are diagnosed by:

• chest X-ray
• chest CT
• echocardiogram
• D-dimer test
• arterial blood gas (ABG) test
• pulmonary angiography

Treatment

DVTs and PEs share similar treatment methods. Thrombolytic medication or anticoagulants will frequently be prescribed. In the case of a PE, this is usually in an intravenous form for speedy treatment. An inferior vena cava (IVC) filter is sometimes placed to prevent the thrombus from traveling from the legs to the heart or lungs. Balloon pulmonary angioplasty is used to remove PEs from the lungs, especially in the case of multiple PEs.

After the thrombus resolves, patients may need to be on an anticoagulant medication for a period of time (usually six months) to reduce the risk of a recurrence. The use of compression socks is encouraged, especially when traveling or when the ability to move around is limited, to prevent blood from pooling in the patient’s legs.

Cardiovascular Trauma

Cardiovascular trauma usually occurs during a traumatic event such as a motor vehicle accident, during blunt trauma such as a forceful football tackle, or during penetrating trauma such as a stabbing. Types of cardiovascular trauma include a myocardial contusion, coronary artery injury, papillary muscle rupture, or even complete cardiac rupture, which is nearly always fatal.

A patient who has experienced cardiovascular trauma has an increased risk of a thromboembolic event, pericardial tamponade, dysrhythmias, and diminished cardiac output.

Assessment

The patient may complain of chest pain or tenderness to palpation and may exhibit bruising on their chest after some time has progressed after the trauma. If the trauma is penetrating, the entry site should be obvious. Any foreign bodies that are present should not be removed until imaging has been completed. The patient may also complain of dizziness or experience hypotension if cardiac output is affected.

The diagnosis is made based on imaging studies that include a chest X-ray, CT scan, cardiac MRI scan, and echocardiogram. An ECG should be obtained to check for any arrhythmias. Lab work includes cardiac enzymes such as creatinine kinase and troponins. The levels will increase over time based on the amount of damage that has occurred to the cardiac muscle.

Treatment

The treatment that is required is largely based on the type of injury that has occurred. A myocardial contusion will likely require inpatient monitoring/continuous cardiac telemetry for several days, along with serial labs. Penetrating trauma will require surgical repair, while a papillary muscle rupture requires valve repair or replacement. Coronary artery injuries will often require surgical repair as well. A myocardial rupture can be surgically repaired when caught early, but it is often fatal. Prompt surgical intervention is key when indicated.

Cardiogenic and Obstructive Shock

In cardiogenic shock, the heart is unable to pump enough blood to circulate around the body and provide oxygen. Organ damage and loss of consciousness occurs swiftly under these circumstances. Cardiogenic shock results most commonly from an acute anterior wall myocardial infarction. Other causes to consider include papillary muscle and/or ventricular septum rupture, prolonged tachyarrhythmias, hypertensive medications, and pericarditis/myocarditis.

Obstructive shock occurs when a physical obstruction prevents blood from being pumped efficiently out of the heart. Common causes include pulmonary embolism, cardiac tamponade, and tension pneumothorax.

Assessment

Symptoms of both cardiogenic and obstructive shock include:

• hypotension
• tachycardia
• tachypnea
• shortness of breath
• decreased urine output
• diminished peripheral pulses
• jugular vein distension
• altered mental status (in severe cases)

Evaluate any patients who are at risk for cardiogenic shock or obstructive shock very closely. Prompt identification and initiation of treatment can be lifesaving.

The hallmarks of cardiogenic and obstructive shock include:

• systolic blood pressure less than 90 mm Hg
• mean arterial pressure less than 60 mm Hg
• metabolic acidosis
• hypoxia
• hypocapnia
• lactic acidosis
• elevated BUN, K, and BNP

An EKG can reveal abnormal heart rhythms including supraventricular tachycardia, ventricular tachycardia, sinus bradycardia, and atrioventricular block. The obstructive process can be diagnosed using an X-ray, CT scan, or echocardiogram.

Treatment

Initial medication treatment is much the same for both types of shock. Treatment includes intravenous dobutamine to increase cardiac contractility, intravenous norepinephrine if systolic blood pressure is less than 70 mm Hg, initiation of an intra-aortic balloon pump (IABP) to aid in cardiac blood flow, and treating the underlying cause.

In the case of an acute myocardial infarction, prompt revascularization should take place, either via percutaneous coronary intervention or coronary arterial bypass graft. If the papillary muscle has ruptured, then a valve replacement will be necessary. If shock is obstructive, a pulmonary embolism can be removed through a pulmonary embolectomy and initiation of anticoagulants and/or fibrinolytic therapies.