Pericarditis and Pericardial Effusion — ECG Changes and Tamponade

Begin with the anatomical compartment. The pericardial sac surrounds the heart; its visceral serous layer lies on the cardiac surface as the epicardium, while the parietal layer lines the outer sac. The intervening potential space contains lubricating fluid. An inflammatory process involves the pericardium, an effusion occupies the space, and tamponade describes the effect of raised pressure on cardiac filling.

These diagnoses overlap, but they are not interchangeable. A patient can have painful acute pericarditis with little detectable fluid. Another can have a large, slowly developing malignant effusion without classic inflammatory chest pain. A rapidly accumulating haemopericardium can cause shock before the sac has time to accommodate much additional fluid. The clinical question therefore has both an anatomical component and a haemodynamic component.

In many developed settings, acute pericarditis is idiopathic or presumed viral. Tuberculosis deserves particular attention in endemic settings and in immunocompromised patients. Other important associations include bacterial infection, malignancy, autoimmune disease, renal failure, trauma and cardiac procedures. The same broad list helps explain effusion, although its relative importance depends on the clinical setting.

Post-cardiac injury inflammation can follow myocardial infarction, cardiac surgery or other injury. Dressler syndrome is a delayed immune-mediated post-infarction syndrome. Keep that mechanism separate from an immediate mechanical complication such as myocardial rupture producing haemopericardium. Both can involve the pericardium, but their time course, urgency and treatment are very different.

A revision vignette often supplies the cause indirectly: uraemia, a known tumour, a recent infarction, fever with immunosuppression, or blunt chest trauma. Use those clues to guide investigation. Avoid treating all effusions as viral pericarditis; anti-inflammatory treatment cannot replace drainage of tamponade or treatment of an identified infection.

The characteristic pain is pleuritic and positional: inspiration and lying flat can worsen it, while sitting up and leaning forward often help. Pain may radiate towards the trapezius ridge through phrenic nerve involvement. This pattern is useful, but chest pain still requires assessment for acute coronary syndrome, pulmonary embolism and aortic disease when the presentation could fit those emergencies.

A pericardial friction rub is a highly specific clue when heard, but it can be transient. Its absence does not exclude the diagnosis. A pericardial rub follows cardiac movement, whereas a pleural rub is related to breathing. Asking the patient to hold their breath can help distinguish them; interpretation still belongs within the full clinical assessment.

• Use the classic exam checklist: characteristic chest pain, friction rub, widespread ECG changes and new or worsening effusion.
• Measure inflammatory markers and troponin; troponin elevation may indicate associated myocardial involvement.
• Obtain echocardiography to assess fluid, tamponade physiology and ventricular function.
• Interpret persistent fever, suspected bacterial disease, immunosuppression or haemodynamic compromise as reasons for a more intensive assessment.

When inflammation involves both myocardium and pericardium, elevated cardiac biomarkers and ventricular dysfunction influence the diagnosis and management. Do not describe all troponin-positive chest pain as infarction, or dismiss myocardial involvement because a patient has a pericardial rub. The clinical distinction depends on the combined evidence.

The classic early pattern is widespread concave ST elevation with PR depression. Lead aVR often shows the opposite pattern, including ST depression and PR elevation. The distribution is more helpful than the word concave alone: pericarditis usually produces changes across several territories, whereas coronary occlusion usually follows a coronary distribution.

Not every patient passes through every stage, and the ECG may be nondiagnostic. Regional pericarditis can also occur. Conversely, concave ST elevation does not reliably exclude myocardial infarction. Territorial changes, reciprocal depression beyond the usual aVR pattern, evolving Q waves, regional wall-motion abnormalities and the clinical presentation should trigger assessment for ischaemia.

Echocardiography is the key investigation because it identifies pericardial fluid and evaluates its effect on the moving heart. Simple fluid is usually seen as an anechoic space, while blood clot or infected material can make the appearance more complex. The echocardiogram should answer whether the fluid is present, where it lies and whether cardiac filling is compromised.

A large effusion may produce low QRS voltage or electrical alternans. In the classic effusion mechanism, the heart swings within the fluid-filled sac, changing its electrical orientation and the apparent QRS amplitude. Electrical alternans is a useful clue but lacks sensitivity; its absence does not reassure against a significant effusion or tamponade.

Chest radiography may show an enlarged cardiac silhouette in a sizeable effusion, but it cannot determine haemodynamic significance. A rapidly accumulating effusion can be dangerous before a conspicuously enlarged silhouette develops. CT or cardiac MRI can clarify anatomy or associated disease when indicated, but echocardiography remains central in urgent bedside assessment.

• A friction rub points towards inflammation; electrical alternans points towards an effusion-related swinging-heart mechanism.
• A large effusion on imaging does not automatically equal tamponade.
• A patient with hypotension and raised venous pressure needs assessment of filling physiology, even if the ECG is unimpressive.
• Etiological testing may include renal function, thyroid testing, inflammatory assessment and targeted investigation for infection or malignancy.

As intrapericardial pressure rises, the heart cannot fill normally during diastole. Stroke volume and cardiac output fall, while venous blood backs up upstream. The rate of fluid accumulation matters because the pericardium accommodates gradual distension better than abrupt expansion. This explains why an acute collection can be more dangerous than a larger chronic one.

Pulsus paradoxus is an inspiratory fall in systolic blood pressure of more than 10 mm Hg. During inspiration, increased right-sided filling within a constrained pericardial space shifts the interventricular septum towards the left ventricle. Left ventricular filling and stroke volume decrease, exaggerating the usual respiratory blood-pressure variation.

Pulsus paradoxus supports tamponade but is neither universal nor exclusive to it. Severe obstructive airway disease can also cause it. Kussmaul sign means a paradoxical inspiratory rise in jugular venous pressure, a different observation. It is not typical of pure tamponade and suggests constrictive physiology or another right-sided filling abnormality when present.

Pericardial pressure first affects chambers when their internal pressure is lowest. Classic echocardiographic findings include right atrial collapse during systole and right ventricular collapse during diastole. These timing distinctions are frequent examination traps. State both the chamber and the phase rather than recalling chamber collapse as an undifferentiated sign.

Other supportive features include a dilated inferior vena cava with reduced respiratory variation and exaggerated respiratory changes in ventricular filling. Mitral inflow tends to decrease during inspiration, while right-sided filling increases. These findings express ventricular interaction within the restricted pericardial space; they must be interpreted alongside respiration, loading conditions and the clinical state.

• Identify the effusion, then examine chamber motion and filling.
• Match chamber collapse to the phase of the cardiac cycle.
• Assess respiratory changes in Doppler inflow and vena caval size.
• Correlate all findings with blood pressure, venous pressure and tissue perfusion.

Jugular venous pressure in tamponade may show a blunted or absent y descent, reflecting impeded early ventricular filling. This is different from simply noticing neck-vein distension. For a tracing question, recognize that the venous waveform adds physiological information; for an unstable clinical vignette, it should never delay emergency assessment and drainage.

Uncomplicated inflammatory pericarditis is generally treated with an NSAID or aspirin plus colchicine, with appropriate assessment of contraindications and treatment of an identified cause. Colchicine helps reduce recurrence. Corticosteroids are reserved for selected circumstances rather than routine first-line use, because they can complicate recurrence and tapering. Avoid importing a universal dose into a revision answer without considering the patient and indication.

Haemodynamically unstable tamponade requires urgent pericardial drainage. Oxygen, intravenous fluids and vasoactive support can be temporary bridges, but they do not remove the pressure around the heart. Drainage may be percutaneous or surgical depending on the cause, anatomy and clinical setting. Traumatic or clotted haemopericardium may need operative treatment.

1. Recognize impaired perfusion and call for urgent specialist support.
2. Use echocardiography promptly to guide diagnosis and drainage when feasible.
3. Stabilize concurrently while arranging definitive drainage.
4. Avoid positive-pressure ventilation when feasible because it can further impair venous return.
5. Treat the underlying cause and reassess after drainage; persistent constrictive physiology suggests an additional pericardial process.

A small, stable effusion can often be monitored, while a symptomatic or diagnostically concerning effusion may require intervention. The decision is driven by cause and physiology, not a rule that all visible fluid must be drained. In revision, contrast a stable incidental effusion with obstructive shock: the same compartment is involved, but the required action differs greatly.