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| Discussion |
Case Report: A 14-year-old female patient presented with complaints of breathlessness, dry cough and fever since 15 days. The patient was a known case of pulmonary tuberculosis on anti-tuberculous treatment - Category II for 6 months prior to presentation. On examination, the patient had mild tachycardia (102/min). The rest of the vital signs were stable. The patient had dullness on percussion in both lower thoracic fields with diminished breath sounds. Heart sounds were normal.
Laboratory investigations were unremarkable except for an elevated ESR (42mm at the end of the first hour) and a hemoglobin level 8.7g%.
A frontal chest radiograph of the chest showed bilateral blunting of cardiophrenic angles with homogenous opacification of both lower lung fields suggestive of pleural effusion (left > right). Mild cardiomegaly was present [Figure 1].
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Fig. 1 |
Target 2D echocardiography performed showed a moderate pericardial effusion. There was a suspicion of pericarditis and restrictive cardiomyopathy.
Cardiac MRI was performed on a 1.5T superconducting system. ECG gated single-shot, fast spin-echo MR images in multiple planes showed diffuse, concentric thickening of the pericardium. On T1w [Figure 2] and T2 w [Figure 3] images, the pericardium appeared hypointense - which seemed to represent calcification
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Fig. 2 |
Fig. 3 |
The IVC was dilated [Figure 4] and measured 2.5 cms in diameter and showed lack of distensibility. Hepatic veins were dilated.
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Fig. 4 |
The right atrium was enlarged. There was generalised hypokinesia of the myocardium. Cine MR images were obtained during free respiration [Video 1] which showed paradoxical movement of the interventricular septum.
Video 1 |
The interventricular septum was ‘S’-shaped on four chambered view [Figure 5].
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Fig. 5 |
Short axis images showed flattening of the interventricular septum and bowing towards the left ventricle [Video 2].
Video 2 |
In addition, an approximately 2.1 cm diameter soft tissue mass was seen in the apex of the left ventricle in close proximity to the interventricular septum. This mass was hyperintense on T1w images [Figure 2] and hypointense on T2w images [Figure 6].
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Fig. 6 |
On dynamic, post contrast MR perfusion images, there was no enhancement of the mass lesion [Figure 7 a; b].
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Fig. 7 A |
Fig. 7 B |
Delayed images showed diffuse enhancement of the left ventricular myocardium [Figure 8 a; b]. Massive bilateral loculated pleural effusions were seen.
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Fig. 8 A |
Fig. 8 B |
Plain CT scan of the chest confirmed pericardial thickening. Hypodense left ventricular clot and bilateral pleural effusions were also seen. No pericardial calcification was seen [Figure 9; 10]. Lung window settings revealed basal atelectasis [Figure 11].
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Fig. 9 |
Fig. 10 |
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Fig. 11 |
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This patient was managed conservatively on digoxin, diuretic and heparin. Pericardiectomy was planned.
Diagnosis:
Tuberculous constrictive pericarditis and global hypokinesia secondary to myocarditis with left ventricular clot.
DISCUSSION:
Constrictive pericarditis occurs when a thickened fibrotic pericardium, of whatever cause, impedes normal diastolic filling. It is usually a long-term consequence of either acute or chronic forms of pericarditis. Pericardial effusion leads to pericardial organization, chronic fibrotic scarring, calcification, and restricted cardiac filling. This pathophysiology is responsible for the typical imaging manifestations of constrictive pericarditis.
Constrictive pericarditis may be diffuse or focal. The commonest cause of focal pericardial thickening is post-operative - occurring over the right ventricle. Diffuse pericardial thickening occurs as a sequel to infective/inflammatory conditions or post-myocardial infarction (Dresseler’s syndrome). In India , the commonest cause is tuberculosis.
Tuberculosis involving the heart accounts for only 0.5% of cases of extrapulmonary tuberculosis. It causes inflammation of both, the myocardium and the pericardium. Tuberculous pericarditis leads to irregular thickening of the pericardium. This is often associated with mediastinal lympadenopathy. Most patients have distention of the inferior vena cava to a diameter exceeding 3 cm; pleural effusions, typically bilateral; and deformities of the intraventricular septum. Less than 20% of patients have pericardial effusions or develop localized pericardial calcification.
The closest clinical and radiologic differential diagnosis of constrictive pericarditis is restrictive cardiomyopathy. Both have overlapping clinical features. However, it is important to distinguish between there two conditions as the treatment differs. The treatment of constrictive pericarditis is pericardiectomy, while restrictive cardiomyopathy is a rapidly progressive condition that may require cardiac transplantation.
While 2D echocardiography is the first-line investigation used, it has limitations due to operator dependence and poor window availability. MRI has 93% sensitivity in differentiating constrictive pericarditis from pericardial effusion. Cine imaging has the advantage of depicting abnormal movement of the interventricular septum and myocardial hypokinesia. In addition, myocardial inflammation can be evaluated by post contrast enhancement.
Thickness of normal pericardium is 1-2 mm. The demonstration of thickened pericardium on MRI or CT does not equate with the diagnosis of constrictive pericarditis.
Signs of constrictive pericarditis on CT/MRI include-
MRI can also accurately evaluate the thickness of the posterior left ventricular wall. This is of prognostic significance. Radiographic demonstration of thinning of the free wall of the left ventricle is associated with increased mortality after pericardiectomy due to myocardial dysfunction.
Thrombi in the ventricles are commonly seen near areas of myocardial hypokinesia/ akinesia. The differential diagnosis of soft tissue lesions in the heart chambers includes benign or malignant tumours like rhabdomyoma, myxoma or rhabdomyosarcoma. Study of the enhancement pattern of the lesion during the first pass of contrast (perfusion study) is useful to distinguish thrombi from tumours as thrombi do not enhance.
Conclusions:
Due to its multiplanar scanning capability, excellent spatial resolution and cine imaging, MRI is the modality of choice in the diagnosis of constrictive pericarditis and differentiating it from restrictive cardiomyopathy, pericardial effusion etc.