<unk>  can be caused by several physiologic mechanisms. Anatomically, these can be grouped into: * cardiac causes, * pulmonary causes and * non-pulmonary and non-cardiac causes. Considered physiologically,<unk>  is caused by: * decreased right heart functional reserve, e.g. myocardial infarction and tamponade, * right ventricular inflow or outflow obstruction, e.g. superior vena cava obstruction and pulmonary embolism, and * decreased blood to the left heart due to lung hyperinflation (e.g. asthma, COPD) and anaphylactic shock. List of causes Cardiac: * constrictive pericarditis. One study found that<unk>  occurs in less than 20% of patients with constrictive pericarditis. * pericardial effusion, including cardiac tamponade * cardiogenic shock Pulmonary: * pulmonary embolism * tension pneumothorax * asthma (especially with severe asthma exacerbations) * chronic obstructive pulmonary disease Non-pulmonary and non-cardiac: * anaphylactic shock * hypovolemia * superior vena cava obstruction * pregnancy * obesity<unk>  has been shown to be predictive of the severity of cardiac tamponade.<unk>  may not be seen with cardiac tamponade if an atrial septal defect or significant aortic regurgitation is also present.
Pulsus paradoxus
Pulsus alternans
Collapsing pulse
Pulsus bigeminus
Third heart sound
Heart click
Shifting dullness
Right axis deviation