Cardiac tamponade - Disorders of the pericardium

Cardiac tamponade

Definition

Pericardial/cardiac tamponade is an acute condition in which fluid in the pericardial sac causes impaired ventricular filling.

Aetiology

The commonest cause of tamponade is malignancy. It may occur with other causes of pericarditis and effusion and also as a post-traumatic complication following cardiac catheterisation, cardiac perforation, cardiac surgery or chest injury.

Pathophysiology

The pericardium is a non-distensible bag around the heart. Once the space between the pericardium and the heart becomes full of fluid the ventricles are prevented from filling properly during diastole thus reducing the cardiac output.

Clinical features

Hypotension with sinus tachycardia and a raised JVP, which may increase further on inspiration (Kussmaul’s sign). The pulse is of low volume and reduced on inspiration (pulsus paradoxus). Oliguria or anuria develops rapidly and eventually there is hypotension and shock.

Complications

If not identified and treated, cardiac tamponade may rapidly lead to death from low output state.

Investigations

Patients are investigated as for pericardial effusion. If the tamponade is haemodynamically compromising the diagnosis may have to be clinical, but ideally an echocardiogram is done immediately on suspicion. Echocar-diogram is diagnostic, can estimate the volume of fluid present and assess the severity of cardiac compromise.

Management

If there is compromise of the cardiac output, needle aspiration of the pericardium should be performed via the xiphisternal route, preferably under radiographic guidance. The needle is inserted 1 cm below the xiphisternum and angled to point towards the left shoulder (45Ëš). If the ECG is left in place, with the V lead attached to the needle, penetration of the myocardium shows up as ST elevation. The relief following pericardiocentesis is often temporary, so a fine catheter should be inserted for continuous drainage until the underlying condition is corrected. Definitive surgery is required if needle drainage is unsuccessful.