Abstract: Cardiac tamponade is a life threatening situation in which fluid within the pericardial cavity compresses the heart preventing its filling during diastole.
Pericardial effusion is the collection of fluid between the parietal and visceral layers of the pericardium. Normally there could be a thin layer of fluid, about twenty to fifty milliliters, in the pericardial cavity. When fluid accumulates gradually in the pericardium due to a slow disease process, the parietal pericardium stretches to accommodate more fluid in the range of five hundred milliliters. But rapid collection of fluid as in the case of bleeding into the pericardial cavity, is less tolerated and features of tamponade and hemodynamic collapse may develop with as little as hundred milliliters of pericardial fluid.
Causes of cardiac tamponade
Any cause for rapid collection of fluid in the pericardial cavity can cause tamponade. By and large, malignant effusion is probably the most important cause of cardiac tamponade, with large collections of hemorrhagic pericardial effusion. Traumatic tamponade can occur with any injury involving the heart. Proximal aortic dissection can leak into the pericardial cavity and cause hemorrhagic pericardial effusion and tamponade. Tuberculous pericardial effusion can also cause cardiac tamponade, though less dramatic than in case of a hemorrhagic pericardial effusion. Tuberculous pericardial effusion can sometimes be hemorrhagic as well.
Interventional procedure related cardiac tamponade is now being managed in the cardiac catheterization laboratory in fair numbers. Coronary perforation can occur during percutaneous interventions causing pericardial tamponade. Procedures involving atrial septal punctures like balloon mitral valvotomy and ablation of atrial fibrillation in left atrium carry a risk of cardiac perforation and tamponade. Even simple right heart catheterisation can result in cardiac tamponade, especially while manipulating relatively stiff catheters at the vulnerable inferior vena cava – right atrial junction. Cases are on record in which both temporary and permanent pacing leads have perforated the right ventricles. Temporary pacemaker leads are more likely to cause perforation as they are stiffer.
Management of cardiac tamponade – pericardiocentesis
Management of cardiac tamponade is by immediate pericardiocentesis. In an emergency situation, urgent bedside aspiration may be life saving. Echocardiographic confirmation is useful in establishing the cause of hemodynamic collapse as cardiac tamponade. Large collection of fluid in the pericardial space compressing the heart all around can be easily seen on echocardiography. Classical sign of tamponade on echocardiography is the diastolic collapse of right atrium and right ventricle, which prevents adequate filling of the heart.
Pericardiocentesis under fluoroscopic guidance is more often resorted to these days unlike the direct bedside aspiration of the yesteryears. Many of the cases of cardiac tamponade occur during invasive procedures in the current interventional era, making fluoroscopic guidance readily available on the spot. The pericardial space is usually approached from the subxiphoid route and standard Seldinger technique with initial needle puncture followed by guidewire introduction is usual. Once the guidewire position has been confirmed, an arterial sheath is usually introduced over the guide wire. A pigtail catheter introduced through the sheath is used for therapeutic pericardial aspiration. If recollection is expected, the pigtail catheter can be left in situ for a few days for follow up bedside aspiration with all aseptic precautions. In case of large periprocedural hemorrhagic pericardial tamponade, it is usual practice to auto transfuse the blood drained into the circulation using a three way adaptor. This reduces the blood loss in an emergency and buys time while the patient is being shifted for surgical repair of the periprocedural perforation.