Cardiac Emergencies

The heart has no oxygen reserve

The coronary arteries branch off the base of the aorta, and they are the first vessels to receive oxygenated blood from the heart itself. Heart cells are constantly working, and without perfusion they become hypoxic and can die very quickly. This is why a blocked coronary artery is such an urgent problem.

Acute coronary syndrome (ACS), also called cardiac compromise, is a blanket term for any situation in which the blood supply to heart cells is blocked or disrupted, whether abruptly by a sudden clot or gradually by the narrowing of plaque. The resulting hypoxic condition is called ischemia. Most of the damage that ischemia causes, short of actual cell death, can be corrected by restoring perfusion.

Signs & symptoms of ACS

Chest discomfort is the most common finding in ACS, but patients describe it in very different ways: as pain, pressure, squeezing or aching. It may stay localized or radiate to the jaw, the neck, either arm or the epigastrium. It can also be absent entirely, and that is especially true in older adults, women and diabetic patients.

The other symptoms are less specific. The patient may have dyspnea, nausea or vomiting, syncope or near-syncope, vague fatigue, or sudden sweating, a combination often mistaken for "coming down with the flu." On examination you may find an abnormal pulse, whether bradycardic, tachycardic or irregular, an abnormal blood pressure, and anxiety or a "feeling of impending doom."

Because presentations vary so widely, treat any patient whose picture matches the pattern as cardiac rather than trying to talk yourself out of the diagnosis.

Managing ACS — assessment & 12-lead

Management begins with the primary assessment, followed by the history using OPQRST and SAMPLE, and then a set of baseline vital signs. Levine's sign, in which the patient clutches the chest, together with sweating, pale or gray skin, and anxiousness with a sense of impending doom, all suggest that the discomfort is from ACS.

Many states allow EMTs to acquire a 12-lead electrocardiogram (ECG). Interpretation is outside the EMT scope, but acquiring the tracing and transmitting it speeds the hospital's diagnosis. Place the limb leads first, on the arms below the shoulder and on the legs below the hip, and then place V1 through V6 at the standard chest landmarks.

Treatment steps

Treatment of ACS follows a set sequence:

1. Positioning. A patient with breathing difficulty is generally sat up; a hypotensive patient often feels better lying down.
2. Oxygen. The target is an SpO2 of 94% or higher, and no higher than necessary. Give high-concentration oxygen for respiratory failure, a low SpO2 or a critical appearance. An alert patient who is not in distress and has a normal SpO2 receives no oxygen.
3. Immediate transport if the patient has no cardiac history, has a cardiac history but no nitroglycerin on hand, or has a systolic blood pressure below the protocol threshold.
4. 12-lead ECG, if you are trained, equipped and authorized.
5. Aspirin, up to 325 mg by mouth (PO), chewed. Do not give it if there is an aspiration risk, if the patient already took aspirin earlier today, if the patient is allergic, if there is recent GI bleeding, or, depending on protocol, if the patient is already on a prescribed blood thinner.
6. Nitroglycerin. Assist with it only when all of the conditions are met: the patient has chest discomfort and a cardiac history, the nitroglycerin is physician-prescribed and the patient has it, the systolic blood pressure is above the threshold, the patient has taken no erectile dysfunction (ED) medication within 48–72 hours, and medical direction authorizes it. The dose may be repeated in 5 minutes if the blood pressure remains adequate, to a maximum of 3 doses.

Drive smoothly. Sudden starts, stops and turns and unnecessary sirens add stress to a heart that is already under stress.

Coronary artery disease & angina pectoris

Coronary artery disease (CAD) is the narrowing or blockage of the coronary arteries by the buildup of plaque. Its non-modifiable risk factors are heredity and age; its modifiable risk factors are hypertension, obesity, inactivity, high cholesterol and smoking. CAD itself is usually not an emergency.

Angina pectoris is chest discomfort that occurs when a narrowed artery cannot meet the increased demand of exertion or stress. Its distinguishing feature is that the symptoms subside with rest, typically within about 5 minutes. In the field, however, angina and a myocardial infarction (MI) can look identical, so treat every symptomatic patient as a possible MI, using the same ACS protocol, until proven otherwise.

Acute myocardial infarction (AMI)

Plaque narrows and roughens a vessel, and the roughened surface promotes the formation of a clot, or thrombus. The clot may block the vessel completely, which is an occlusion, or a piece may break free and lodge downstream, which is an embolism. Either way the result is an acute myocardial infarction (AMI). An AMI has two dangerous consequences. Dysrhythmia is the most common cause of death from an MI. Mechanical failure is rarer, and it can progress to cardiogenic shock.

"Time is muscle." The faster the patient reaches the hospital and receives intervention, the less heart muscle is permanently lost. EMT treatment begins with confirming a pulse and breathing, because some AMI patients present in cardiac arrest. Transport is the single most important treatment. Contact ALS, keep an AED nearby, give aspirin and nitroglycerin per protocol, and keep the patient calm. Do not let an AMI patient walk.

Heart failure (HF/CHF) & pulmonary edema

In heart failure (HF/CHF) the heart continues to pump, but inefficiently, and the side that fails determines where the pressure backs up. In right-sided failure, pressure backs up into the vena cava, producing jugular venous distention (JVD), abdominal swelling and pedal edema. In left-sided failure, pressure backs up into the pulmonary vein, the alveolar capillaries leak fluid, and the result is pulmonary edema, with respiratory distress, crackles and possibly pink frothy sputum.

The primary assessment comes first, because a patient in heart failure can decompensate to inadequate breathing. It is followed by a detailed cardiovascular exam and continuous vital signs. Contact ALS immediately, apply CPAP if protocol allows, and note that some systems allow the EMT to give nitroglycerin for acute pulmonary edema.

Aneurysm & pediatric cardiac notes

An aneurysm is a weakened arterial wall, either congenital or related to plaque, that expands and dilates or tears in its middle layers. Rupture causes rapid, life-threatening internal bleeding. The most common sites are the aorta and the brain, and a ruptured artery in the brain is a hemorrhagic stroke.

Most pediatric cardiac conditions are congenital and are usually identified before the newborn leaves the nursery. When a child has a chronic cardiac condition that is unclear to you, consult the caregivers to establish the child's baseline and ask why EMS was called. Manage any problems found in the primary assessment the same as you would for any patient, and transport to a facility equipped for the child's condition.