Cardiac tamponade is a life-threatening condition in which the gradual accumulation of a large amount of fluid (~1000 ml) or rapid accumulation of a small amount of fluid (~150 to 200 ml) in the pericardial space prevents cardiac expansion (i.e. diastolic relaxation). The fluid may be serous, purulent, chylous, hemorrhagic, or a combination of these. Clinical features of cardiac tamponade include chest pain, difficulty breathing, syncope, a decreasing level of consciousness, low blood pressure, distended neck veins, pulsus paradoxus and muffled heart sounds. The diagnosis is mostly clinical, however, investigations in less emergent situations include electrocardiography, chest x-rays, or the gold standard: transesophageal or transthoracic echocardiography. Treatment is via pericardiocentesis through either an echocardiography guided para-apical approach or, in places where imaging is not readily available, a blind sub-xiphoid approach.
In constrictive pericarditis, the pericardium becomes fibrotic and thickened due to prolonged inflammation, thereby forming a hardened enclosure around the heart. This limits adequate cardiac relaxation, thus greatly reducing end diastolic volume and therefore, the stroke volume. Symptoms include easy fatigability, dyspnea, abdominal and leg swelling, as well as symptoms of the underlying cause. Clinical signs that may be elicited include a pericardial knock, Kussmaul's sign and signs associated with the underlying cause. Causes include, but are not limited to, tuberculosis (common in developing countries and immunocompromised individuals), chronic pericarditis (viral, fungal, or parasitic), post-surgical pericarditis, and ionizing radiation-induced pericarditis. Treatment is by subtotal or radical pericardiectomy.
Pericardiectomy is the surgical removal of the pericardium; this is typically performed when the latter is diseased and fibrosed, thereby impairing adequate expansion of the heart chambers. The procedure is the mainstay of treatment for constrictive pericarditis and may be either subtotal or radical. A pericardiotomy is quite different; it is an incision made into the pericardial space. This is most often performed to gain access to the heart during heart surgery; it may also be used to create a window through which to drain excess pericardial fluid.
Pulseless electrical activity (PEA) is defined as cardiac electrical activity without a palpable pulse. It is due to electromechanical dissociation of the heart. The most common causes of PEA include cardiac tamponade, tension pneumothorax, mechanical hyperinflation and pulmonary embolism. The management involves treatment of the underlying cause and immediate commencement of cardiopulmonary resuscitation, with epinephrine and vasopressin being adjuvant drugs as per ALS guidelines. Defibrillation is not indicated in PEA, as there is no problem with the electrical system of the heart. The use of atropine is no longer recommended.