Emergency Department: Acute Cardiac Pain
Acute cardiac pain results from acute myocardial ischaemia and includes acute MI and unstable angina. Pain or discomfort is typically precordial, radiating or referred to the left arm and jaw, but patients may also experience pain in either arms, left shoulder, back, neck or stomach. This is accompanied by dyspnoea, sweating, stomach discomfort (indigestion or heartburn), nausea and vomiting
Acute cardiac pain results from acute myocardial ischaemia and includes acute MI and unstable angina. Pain or discomfort is typically precordial, radiating or referred to the left arm and jaw, but patients may also experience pain in either arms, left shoulder, back, neck or stomach. This is accompanied by dyspnoea, sweating, stomach discomfort (indigestion or heartburn), nausea and vomiting. Depending on the extent and location of ischaemia, patients may be dizzy (hypotensive due to myocardial failure or dysrhythmias). Sympathetic activation (sweating), radiating pain, referred pain, nausea and vomiting are typical of visceral pain (see Emergency Department: Acute Abdominal Pain, Renal Colic, Biliary Colic and Dysmenorrhoea).
The restoration of adequate myocardial oxygenation is the mainstay of treatment. This is done by increasing arterial partial pressure of oxygen (PO2 ), increasing coronary blood flow, and decreasing myocardial oxygen demand. These steps limit cardiac muscle damage and reverses ischaemic pain. However, early pain control is important in decreasing myocardial oxygen demand as it decreases the stress response.
Supplemental oxygen is usually administered as soon as possible. IV morphine is analgesic, anxiolytic, decreases blood pressure and suppresses the stress response. These effects decrease oxygen demand. Concurrent management includes nitrates, antihypertensives, antiplatelet agents and interventions to restore myocardial perfusion.
Morphine sulphate has been shown to be very effective at suppressing acute cardiac ischaemic pain. It is titrated at a dose of 50 µg/kg every 5 minutes. Keep in mind that morphine delays the antiplatelet effect of ticagrelor.
Acute cardiac pain due to pericarditis is somatic pain, as opposed to ischaemic pain, and is best treated with NSAIDs.
South African Society of Anaesthesiologists (SASA) Guidelines for the Management of Acute Pain in Specific Scenarios 2022