It is a condition caused due to accumulation of fluid in the pericardium, which is the covering of the heart. The fluid collects in between the visceral and parietal pericardium. As considerable fluid gets accumulated, it causes serious obstruction to the inflow of blood into the ventricles thus restricting ventricular filling and outflow. This results in a condition called Cardiac Tamponade. It is highly fatal complication and requires prompt diagnosis and treatment. In some conditions however, it may develop relatively slowly and produce symptoms like dyspnea, orthopnea, hepatic enlargement and jugular venous hypertension, thus resembling right heart failure.
Causes: Main causes are neoplasia, idiopathic pericarditis and uremia. Another cause may be bleeding into the pericardial space which in turn may be caused due to cardiac catheterization, cardiac surgery or trauma.
Pathophysiology: The collection of fluid in the pericardium provides a lot of resistance to the expansion of the ventricles. This raises the intraventricular pressure to higher than normal, which in turn decreases the cardiac output and restricts the ventricular inflow. Collection of fluid may be sudden or may occur over a long period of time. In case the effusion is of sudden onset then even a volume of 200 ml of fluid is sufficient to cause a critical state and if the effusion is of long standing then more than 2000 ml of fluid would be required, as in the case of slowly accumulating effusions the pericardium is able to adapt and stretch.
Signs and symptoms: Paradoxical Pulse is the most important sign of presence of Cardiac Tamponade though not pathognomonic. It represents more than normal (10mm of Hg) decline of the systolic arterial pulse on inspiration. In severe cases, there may be weakness or disappearance of arterial pulse during inspiration. Both ventricles have a tight covering of pericardium. Hence the enlargement of the right ventricle during inspiration compresses and reduces the left ventricular volume. Paradoxical pulse is also seen in some cases of hypovolaemic shock, acute and chronic obstructive airway disease and pulmonary embolus.
On percussion, an area of flatness is produced on the anterior chest wall.
Hypotension is present in most cases.
The lung fields are relatively clear.
Kussmaul’s sign is absent.
The ECG is of low amplitude and electrical alternans of P, QRS, and T waves may be present.
Diagnosis: In cases of Cardiac Tamponade prompt diagnosis and treatment can be lifesaving. Hence the importance of a quick diagnosis cannot be disregarded. Echocardiography is the main tool for diagnosis, apart from the clinical findings mentioned above. In some cases however Trans Esophageal Echocardiography may be needed. A CT or MRI scan does not show thickened or calcific pericardium thus differentiating it from Constrictive Pericarditis.
Differential Diagnosis: It must be differentiated from Constrictive Pericarditis, Restrictive Cardiomyopathy and Right Ventricular Myocardial Infarction.
Treatment: Percardiocentesis is the main stay treatment and is lifesaving. In some cases a small multiholed catheter may be left in situ to aid continuous drainage from the pericardial space. In cases of recurrent Cardiac Tamponade, surgical drainage may be needed to be performed through limited thoracotomy.
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