Anatomy Thorax Abdomen · Year 1 · from Anatomy Thorax Abdomen
Case 3: Coronary Artery Disease - Acute Anterior STEMI
Clinical Presentation
A 62-year-old male with a history of hypertension, diabetes, and hyperlipidemia presents with severe substernal chest pain that began 45 minutes ago while watching television. The pain radiates to his left arm and jaw. He describes the pain as a "heavy pressure" and rates it 9/10 in severity. He is diaphoretic and appears pale. Vital signs show blood pressure of 100/70 mmHg, heart rate of 95 beats per minute, and respiratory rate of 22 breaths per minute.
ECG demonstrates ST-segment elevation in leads V1-V4 with reciprocal ST depression in leads II, III, and aVF, consistent with an acute anterior ST-elevation myocardial infarction (STEMI). He is taken emergently for percutaneous coronary intervention, which reveals complete occlusion of the proximal left anterior descending artery. Successful stent placement restores blood flow, and post-procedure echocardiogram shows anterior wall hypokinesis but preserved overall left ventricular function.
Key Anatomical Points
- The left coronary artery arises from the left aortic sinus and divides into the left anterior descending (LAD) and circumflex arteries
- The LAD runs in the anterior interventricular sulcus toward the apex, supplying the anterior left ventricle, anterior interventricular septum, and apex
- Proximal LAD occlusion causes large anterior infarctions and is sometimes called the "widow maker"
- The LAD gives off septal perforating branches that supply the interventricular septum and diagonal branches that supply the lateral wall
Key Learning Points
- Understanding coronary artery distribution predicts infarct territory: LAD (anterior), RCA (inferior), LCx (lateral/posterior)
- The coronary arteries fill during diastole when the aortic valve is closed and blood enters the coronary ostia
- Cardiac pain follows sympathetic afferent pathways to spinal segments T1-T4, explaining referred pain to the left arm, jaw, and neck (dermatomal distribution)
- The right coronary artery supplies the SA node in 55% and AV node in 80% of individuals, so RCA occlusion may cause arrhythmias