Cardiology · Pericardial Disease
The facts most likely to be tested
Cardiac tamponade presents with the classic Beck triad of hypotension, jugular venous distension (JVD), and muffled heart sounds.
The most sensitive physical exam finding is pulsus paradoxus, defined as a systolic blood pressure drop >10 mmHg during inspiration.
Echocardiography is the diagnostic test of choice, revealing diastolic collapse of the right ventricle and right atrium.
Electrocardiogram (ECG) findings typically demonstrate electrical alternans, which is a beat-to-beat variation in the QRS complex amplitude.
Pathophysiologically, increased intrapericardial pressure restricts diastolic filling, leading to decreased stroke volume and obstructive shock.
The definitive treatment for hemodynamically unstable patients is urgent pericardiocentesis or pericardial window.
Fluid resuscitation with intravenous normal saline is the appropriate bridge to definitive treatment to increase preload and maintain cardiac output.
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A 54-year-old male presents to the emergency department with progressive shortness of breath and lightheadedness following a recent viral illness. Physical examination reveals a blood pressure of 88/60 mmHg, a heart rate of 124 bpm, and distended neck veins. Heart sounds are muffled on auscultation, and the patient exhibits a systolic blood pressure drop of 18 mmHg during inspiration. An ECG shows electrical alternans.
What is the most appropriate next step in management?
Urgent pericardiocentesis
The patient exhibits the classic signs of cardiac tamponade (Beck triad and pulsus paradoxus); because the patient is hemodynamically unstable, immediate decompression via pericardiocentesis is required.
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Etiology / Epidemiology
Caused by pericardial effusion leading to impaired diastolic filling. High-risk: malignancy, trauma, and post-MI.
Clinical Manifestations
Presents with Beck's triad: hypotension, JVD, and muffled heart sounds. Look for pulsus paradoxus.
Diagnosis
Gold standard is echocardiography showing diastolic collapse of cardiac chambers.
Treatment
Immediate pericardiocentesis. Avoid diuretics as they reduce preload required for cardiac output.
Prognosis
High mortality if untreated; 100% mortality without intervention. Rapid resolution follows drainage.
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Epidemiology & Etiology
Common causes include malignancy (lung/breast), idiopathic pericarditis, and cardiac surgery. Trauma (penetrating or blunt) is a frequent cause in emergency settings. Uremia and aortic dissection are critical differentials to exclude.
Pertinent Anatomy
The pericardial sac is a rigid, non-distensible fibrous structure. When fluid accumulates rapidly, the intrapericardial pressure exceeds diastolic pressure, causing cardiac chamber compression.
Pathophysiology
Increased intrapericardial pressure limits venous return and diastolic filling. This leads to decreased stroke volume and compensatory tachycardia. Eventually, the heart cannot maintain cardiac output, resulting in obstructive shock.
Clinical Manifestations
Patients present with Beck's triad: hypotension, JVD, and muffled heart sounds. Pulsus paradoxus (a drop in systolic BP >10 mmHg during inspiration) is a classic finding. Red flags include tachycardia, tachypnea, and altered mental status.
Diagnosis
The echocardiogram is the diagnostic test of choice, demonstrating diastolic collapse of the right atrium and ventricle. ECG may show electrical alternans, a pathognomonic sign of a swinging heart. CXR may reveal an enlarged water-bottle heart.
Treatment
Initial management is fluid resuscitation to maintain preload. The definitive treatment is pericardiocentesis. Avoid diuretics and positive pressure ventilation as these decrease venous return and worsen shock.
Prognosis
Untreated tamponade is universally fatal. Pericardiocentesis provides immediate hemodynamic improvement. Recurrence is possible, necessitating pericardial window in chronic or malignant cases.
Differential Diagnosis
Constrictive pericarditis: presence of pericardial knock and calcification
Tension pneumothorax: absent breath sounds and tracheal deviation
Massive pulmonary embolism: S1Q3T3 on ECG and clear lung fields
Myocardial infarction: ST-segment elevations and elevated troponins
Hypovolemic shock: flat neck veins rather than JVD