Constrictive Pericarditis: Pathogenesis, Etiology

Inflammation of pericardium is known as pericarditis. Inflamed pericardium causes constriction of the heart, this is known as Constrictive Pericarditis.

Pathogenesis of Constrictive Pericarditis

It can occur as the sequelae of Healing of acute fibrinous pericarditis or Healing of serosanguinous pericarditis. Chronic pericardial effusion obliterates the pericardial space, and the fluid gets organized to form granulation tissue. The granulation tissue contracts and forms a scar. The scar encases the heart and later it gets calcified.

Etiology of Constrictive Pericarditis

The most common cause of constrictive Pericarditis is Tuberculous pericarditis. During the healing phase, it gets complicated to form constrictive pericarditis. The other causes of constrictive Pericarditis are: 

• Healing of viral infections 
• Idiopathic pericarditis 
• Trauma to the chest as it causes blunt injury to pericardium due to which the blood in pericardial space can form a blood clot.
• Secondary to cardiac surgery 
• Mediastinal irradiation
• Purulent infections
  • Pyogenic bacteria
    • Streptococcus pneumonia
    • Staphylococcus
    • Neisseria
    • Chlamydia
    • Listeria 
  • Fungal infections
    • Histoplasmosis - cause acute pericarditis

Also Read: Paroxysmal Supraventricular Tachycardia

Pathophysiology of Constrictive Pericarditis

There is limitation of dilatation of ventricles. There is inability of ventricles to fill as the pericardium in constrictive pericarditis is very thick. The diastole is impaired due to rigid and calcified pericardium. Ventricle filling is impaired but early ventricular filling is normal. When the elasticity of pericardium is maximum, then there is no further stretch.

In Cardiac tamponade, Ventricular filling throughout the diastole is impaired causing diastolic collapse of ventricles. This decreases Stroke volume and Cardiac output.

Left atrial and right atrial pressure increases as the ventricular filling is impaired. The atria continuously receive blood and is unable to empty completely to ventricles due to impaired diastolic stretch. There is diastolic dysfunction, but systolic function is normal.

In advanced cases, The fibrosis of pericardium gradually extends to the myocardium, leading to myocardial scarring and myocardial atrophy. 

Subsequently, pulmonary venous pressure increases due to an increase in left atrial pressure.

Clinical features of Constrictive Pericarditis

• Following are the features of left heart diastolic impairment
  • Cardiac output reduced → perfusion reduced → hypoxia.
  • No ATP synthesis - Fatigue 
  • Dyspnea
    • Increase in left atrial pressure → PVP ↑ → PCWP ↑ → pulmonary edema → dyspnea.
• Features of right heart diastolic impairment
  • Hepatic congestion
  • Glisson’s capsule stretch can cause tender hepatomegaly.
  • JVP elevated. 
  • Pedal edema
    • The lower limb is unable to drain into IVC. 
    • Hydrostatic pressure of lower limb increases.
• In advanced cases
  • Anasarca
    • Edema all over the body.
    • The weight of the individual is high. 
    • Abdominal girth - increased due to ascites.
    • Ascites is due to hepatic congestion as there is an increase in portal venous pressure.
    • Abdominal discomfort
  • Energy production within muscle gets impaired due to hypoxia.
    • Skeletal muscle wasting  
    • Cachexia 

Also read: Myoclonus: Causes, Symptoms, Diagnosis and Treatment

On Examination of Constrictive Pericarditis

• JVP elevated.
  • Kussmaul sign is seen due to the failure of jugular venous distension during inspiration. However this sign is not specific for constrictive pericarditis
• Pulse pressure is reduced.
  • SBP reduced due to reduction in cardiac output.

• Paradoxical pulse - pulsus paradoxus
  • Characteristic of cardiac tamponade 
  • During inspiration, there will be a fall in SBP of > 10 mmHg.
• Congestive hepatomegaly - tender
  • Impairment of hepatic function 
  • Elevated bilirubin levels → icterus 
• Ascites is more common than pedal edema. This is called ascites precox.
• In the right heart failure, pedal edema is more prominent. 
• Precordial examination
  • Apical impulse is reduced as it is surrounded by calcified pericardium. 
  • It may retract in systole. 
  • This is called BROADBENT’S SIGN.
• Superior mesenteric and splenic vein drains into portal vein
  • Due to portal hypertension, splenomegaly is also present. 
• Pleural effusion - Due to left ventricular failure. 
• Auscultation
  • Heart sounds are slightly muffled.
  • Additional sound: Pericardial knock- early 3rd heart sound

Also Read: Takotsubo Cardiomyopathy : Definition, Pathogenesis

Investigations of Constrictive Pericarditis

• ECG
  • Low voltage complexes: Amplitude of QRS complexes < 5mm in limb leads and < 10 mm in chest leads.
  • T wave inverted 
• Chest X-Ray
  • In tuberculous pericarditis → calcification of pericardium. This is ppreciated best in lateral view.
  • Kerley B lines -due to interstitial edema
  • Alveolar edema
  • Pleural effusion 
• Transthoracic echocardiography
  • It shows pericardial thickening.
  • The pulmonary venous system and venous caval system are maximally dilated.
• Most accurate investigation - CT/MRI of chest
  • CT/MRI helps to Confirm the diagnosis.
  • Echo is difficult in obese individuals.
  • Also shows myocardial involvement.
• Pericardium should be > 4mm thick to be considered constrictive pericarditis.

Differential Diagnosis of Constrictive Pericarditis

• Cor pulmonale
  • Initial right ventricular dilation and later right ventricular failure.
  • The right side is affected more than the left side.

• Tricuspid stenosis: Tricuspid stenosis is differentiated from constrictive pericarditis by presence of mid-diastolic murmur.

Also read: How to Prepare Dermatology and Venereology for PGMEE

Treatment of Constrictive Pericarditis

Definitive treatment is pericardial resection/ pericardiectomy/ decortication. It should be done as early as possible to prevent constrictive effect on the heart.

Medical Management

• For venous congestion – diuretics
  • Loop / thiazide diuretics 
  • Monitor the patient as cardiac output and blood pressure is already low in the patient.
• If age > 50 years
  • Coronary arteriography must be carried out preoperatively. 
  • As the risk of CAD is high in such patients.
• Pericardiectomy leads to progressive improvement of symptoms.

Prognosis of Constrictive Pericarditis

Poor Prognostic Factors

• History of prior radiation
• Uremic pericarditis (renal) / liver dysfunction
• Higher pulmonary artery pressure 
• Abnormal LV function 
• Older age

Good Prognostic Factors

• Idiopathic etiology 
• Infective etiology

Frequently Asked Questions

Q: What is the most common cause of constrictive pericarditis?

Answer: Tuberculosis

Q: What is the Definitive investigation of constrictive pericarditis?

Answer: CT/MRI

Q: What changes can be observed on CT / MRI in constrictive pericarditis?

Answer: CT/MRI will show a pericardial thickening > 4 mm.

Q: What is Constrictive Pericarditis?

Answer: Inflamed pericardium causes constriction of the heart, this is known as Constrictive Pericarditis

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