# Clinical Cases: Heart - External Features and Pericardium ## Case 1: Acute Pericarditis ### Clinical Presentation A 28-year-old male presents to the emergency department with sharp chest pain that began 2 days after recovering from a viral upper respiratory infection. The pain is retrosternal, radiates to the left shoulder and trapezius ridge, and is described as "stabbing." He reports that the pain worsens when lying flat and with deep inspiration, but improves when sitting forward. He denies any exertional component to the pain. Vital signs reveal a low-grade fever of 38.2C, heart rate of 88 beats per minute, and blood pressure of 120/78 mmHg. On cardiac auscultation, a high-pitched scratchy sound is heard at the left lower sternal border that has three components corresponding to atrial systole, ventricular systole, and early diastole - a characteristic pericardial friction rub. The rub is best heard with the patient leaning forward at end-expiration. ECG shows diffuse ST-segment elevation with PR-segment depression in multiple leads, without reciprocal changes, consistent with acute pericarditis. Echocardiogram shows a small pericardial effusion without signs of tamponade. The patient is treated with colchicine and high-dose aspirin with resolution of symptoms over 2 weeks. ### Radiographic Findings ![Pericarditis ECG](case_01_image.jpg) *Image: ECG changes in acute pericarditis showing diffuse ST-segment elevation and PR-segment depression. The pattern reflects inflammation of the pericardium affecting the underlying epicardium. Source: Wikimedia Commons, CC BY-SA 4.0.* ### Key Anatomical Points - The pericardium consists of an outer fibrous layer and an inner serous layer (with parietal and visceral components) - The visceral pericardium (epicardium) is intimately adherent to the heart surface and contains the coronary vessels - The pericardial cavity normally contains 15-50 mL of serous fluid for lubrication - Inflammation of the pericardium causes the visceral and parietal layers to rub against each other, producing the friction rub - The phrenic nerve (C3-C5) provides sensory innervation to the pericardium, explaining referred pain to the shoulder ### Key Learning Points - The fibrous pericardium is anchored inferiorly to the central tendon of the diaphragm and anteriorly to the sternum by sternopericardial ligaments - The transverse pericardial sinus lies behind the ascending aorta and pulmonary trunk, allowing surgical access for clamping these vessels - The oblique pericardial sinus is a blind cul-de-sac behind the left atrium, bounded by the pulmonary veins and IVC --- ## Case 2: Cardiac Tamponade ### Clinical Presentation A 55-year-old male with end-stage renal disease on hemodialysis presents with progressive dyspnea over 5 days. He reports chest discomfort and a sensation of fullness in his chest. He missed his last two dialysis sessions due to transportation issues. On examination, he appears anxious and is sitting upright. Vital signs show blood pressure of 90/80 mmHg with pulsus paradoxus of 18 mmHg, heart rate of 115 beats per minute, and respiratory rate of 24 breaths per minute. Physical examination reveals distended jugular veins that do not collapse with inspiration (Kussmaul sign), muffled heart sounds on auscultation, and clear lung fields. These findings constitute Beck's triad: hypotension, jugular venous distension, and muffled heart sounds. Bedside echocardiography reveals a large circumferential pericardial effusion with right ventricular diastolic collapse, confirming cardiac tamponade. Emergency pericardiocentesis is performed via the subxiphoid approach under echocardiographic guidance, with drainage of 450 mL of hemorrhagic fluid and immediate hemodynamic improvement. ### Key Anatomical Points - The fibrous pericardium is non-distensible, limiting acute expansion when fluid accumulates rapidly - Rapid fluid accumulation of as little as 150-200 mL can cause tamponade, while slowly accumulating effusions may reach 2 liters before causing hemodynamic compromise - Tamponade occurs when pericardial pressure exceeds central venous pressure, impairing diastolic filling - Right-sided chambers are affected first due to their lower pressures ### Key Learning Points - Pericardiocentesis uses the subxiphoid approach: the needle enters just inferior to the xiphoid process, angled 45 degrees toward the left shoulder - This approach avoids the pleura and lungs, which lie lateral to this trajectory - The needle passes through skin, subcutaneous tissue, linea alba, diaphragm, and parietal pericardium to reach the pericardial cavity - Understanding the surface projections of the heart is essential: the right border at the 3rd-6th right costal cartilages, the apex at the 5th left intercostal space at the midclavicular line --- ## 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