Constrictive Pericarditis

Definition

Etiology

Pathophysiology

1. Ventricular interdependence - The rigid pericardium limits total intrapericardial volume. With respiration, increased preload in one ventricle occurs at the expense of filling in the other. This creates the classic septal bounce and exaggerated respiratory variation in ventricular filling.
2. Dissociation of intrathoracic and intracardiac pressures - The thickened pericardium insulates the heart from the normal respirophasic fall in intrathoracic pressure during inspiration. Negative inspiratory pressure is not transmitted to the cardiac chambers, so the usual gradient driving left-sided filling (pulmonary veins - left atrium) falls during inspiration, reducing LV filling. This is the opposite of what happens in tamponade (where there is a similar dissociation but with an effusion).

Clinical Features

Symptoms

• Dyspnea on exertion (most common)
• Fatigue, weakness, exercise intolerance
• Abdominal distension (from ascites and hepatomegaly)
• Peripheral edema
• Weight gain

Signs

• Elevated JVP - most consistent sign; does not fall with inspiration
• Kussmaul's sign - paradoxical rise (or failure to fall) in JVP with inspiration (classic; also seen in RV infarct and severe right heart failure, but NOT in cardiac tamponade)
• Pericardial knock - early diastolic sound at 0.09-0.12 sec after A2, heard best at apex/left sternal border; high-pitched; represents abrupt cessation of ventricular filling when the rigid pericardium halts expansion
• Hepatomegaly, often pulsatile in early disease, becomes non-pulsatile later
• Ascites - often disproportionate to peripheral edema (resembling liver disease)
• Pleural effusions
• Peripheral edema
• Pulsus paradoxus - present in only ~30% (less prominent than in tamponade); exaggerated when effusion is also present (effusive-constrictive type)
• Atrial fibrillation in some patients
• Normal or mildly reduced apical impulse
• No murmurs typically

Investigations

Electrocardiogram

• Low voltage QRS complexes
• Diffuse T-wave flattening or inversion
• Notched or bifid P-waves (biatrial enlargement)
• Atrial fibrillation in ~25-30%
• Non-specific changes; no ST elevation (as in acute pericarditis)

Chest X-ray

• Pericardial calcification - best seen on lateral view; seen in ~50% of cases (more common with TB etiology); virtually diagnostic of constriction when present
• Normal or mildly enlarged cardiac silhouette (unlike dilated cardiomyopathy)
• Pleural effusions
• No marked cardiomegaly (pericardium limits size)

Echocardiography (primary diagnostic tool)

• Pericardial thickening and calcification (may not be visible if mild)
• Septal bounce ("septal knock") - abrupt posterior motion of the interventricular septum in early diastole; due to ventricular interdependence
• Dilated IVC and hepatic veins (non-collapsing with respiration)
• Biatrial enlargement (less marked than in restrictive cardiomyopathy)
• Normal or mildly reduced ventricular size; preserved systolic function

• Mitral E velocity shows >25% respiratory variation (decreases on inspiration) - distinguishes CP from restriction where variation is <10%
• Preserved or increased medial mitral annulus e' velocity (>9 cm/sec) - opposite to restrictive cardiomyopathy; called "annulus paradoxus" or "annulus reversus"
• Hepatic vein expiratory diastolic flow reversal (in restriction: inspiratory flow reversal)
• Tricuspid inflow increases with inspiration (opposite to mitral)

CT / MRI

• CT - best for detecting pericardial thickening (>4 mm) and calcification; aids surgical planning
• Cardiac MRI - detects pericardial inflammation (T2 STIR edema, late gadolinium enhancement); important for identifying patients who may respond to anti-inflammatory therapy (transient or effusive-constrictive pericarditis); can measure pericardial thickness accurately
• Both distinguish CP from restrictive cardiomyopathy

Cardiac Catheterization (gold standard - invasive)

• Equalization of diastolic pressures - RVEDP = LVEDP = PCWP (within 5 mmHg); usually 15-30 mmHg
• "Dip-and-plateau" or "square root" sign in both RV and LV pressure tracings - rapid early diastolic filling followed by abrupt cessation and plateau (the y-descent is prominent)
• Prominent x and y descents in RA pressure waveform ("W" or "M" pattern)
• Elevated RA mean pressure (>15 mmHg)
• Kussmaul's sign: RA pressure rises or fails to fall with inspiration
• Discordant respirophasic changes in RV and LV systolic pressures (while concordant in restriction)
• Systolic area index >1.1 - ratio of RV to LV stroke work reversal during inspiration

Laboratory

• Hyponatremia, hypoalbuminemia (chronic cases)
• Raised liver enzymes (hepatic congestion)
• BNP levels may be normal or mildly elevated (vs. markedly elevated in dilated/restrictive cardiomyopathy)

Differentiation from Restrictive Cardiomyopathy

Treatment

Medical

• Diuretics - symptomatic relief; use cautiously (excessive diuresis worsens filling)
• Anti-inflammatory therapy (colchicine + NSAIDs/corticosteroids) - for transient or effusive-constrictive CP where active inflammation is documented on CMR; a 3-month trial is reasonable
• Treat underlying cause (e.g., anti-TB therapy for tuberculous pericarditis)
• Salt restriction, rest

Surgical - Definitive Treatment

• Pericardiectomy (pericardial decortication/stripping) - the only definitive cure
  • Should be as complete as possible (both visceral and parietal pericardium)
  • Carried out as early as possible to avoid myocardial atrophy
  • Preoperative coronary angiography required in patients >50 years
  • Operative mortality: 5-10% even in expert centers
  • Benefits are progressive over months post-operatively
• Contraindications: severe myocardial atrophy, markedly impaired renal/hepatic function

Prognosis after Pericardiectomy

• 5-year survival: ~78%; 10-year survival: ~57%
• Best prognosis: idiopathic CP (>85% at 7 years)
• Worst prognosis: radiation-induced CP (myocardial involvement)
• Poor prognostic indicators: older age, radiation etiology, NYHA III-IV, renal dysfunction, hyponatremia, atrial fibrillation, LV systolic dysfunction

Special Variants

• Transient CP - reversible constriction from active pericardial inflammation; responds to anti-inflammatory therapy; resolves within weeks without pericardiectomy
• Effusive-constrictive pericarditis - combination of pericardial effusion + constriction; after pericardiocentesis relieves tamponade, hemodynamics of constriction persist; common in TB pericarditis (>50% in endemic areas); treat active inflammation; wide excision of both pericardial layers if not resolving
• Occult CP - features of CP only manifest after volume loading during cardiac catheterization

Key Points to Remember for Exam

1. CP is a potentially curable diastolic heart failure - early recognition is life-saving
2. Kussmaul's sign + pericardial knock + elevated JVP in a patient with ascites disproportionate to edema = classic triad
3. Septal bounce + exaggerated mitral E velocity respiratory variation + preserved medial e' = hallmarks on echo
4. "Dip and plateau" (square root sign) with equalized diastolic pressures at cath is pathognomonic
5. CP vs tamponade: Kussmaul's sign is ABSENT in tamponade (JVP falls normally); pulsus paradoxus is MORE pronounced in tamponade
6. CP vs restriction: preserved/elevated medial e' in CP (>9 cm/s) vs reduced in restriction
7. Pericardial calcification on lateral CXR (best view) is virtually diagnostic
8. Definitive treatment = pericardiectomy; medical therapy only for transient/inflammatory forms
9. Radiation-induced CP carries the worst surgical prognosis
10. TB is the most common cause in developing countries; idiopathic/post-surgical in developed countries