jugular venous pressure

JVP reflects right atrial (central venous) pressure because the internal jugular vein connects directly to the right atrium without valves. It is measured by finding the highest point of visible pulsation in the internal jugular vein and adding 5 cm (the approximate distance from the sternal angle to the right atrium) to the vertical height above the sternal angle, with the patient at 30-45 degrees.

The JVP waveform has distinct components corresponding to cardiac cycle events: 'a' wave (atrial contraction), 'c' wave (tricuspid bulging during ventricular contraction), 'x' descent (atrial relaxation and downward pull of tricuspid valve), 'v' wave (atrial filling against closed tricuspid valve), and 'y' descent (tricuspid opening and rapid ventricular filling).

Clinical significance: - Elevated JVP: seen in right heart failure, tricuspid regurgitation/stenosis, constrictive pericarditis, cardiac tamponade, pulmonary hypertension, superior vena cava obstruction, and volume overload. - Kussmaul's sign (paradoxical rise in JVP with inspiration): seen in constrictive pericarditis, restrictive cardiomyopathy, and severe right heart failure. - Absent 'a' waves: atrial fibrillation. - Cannon 'a' waves: AV dissociation (e.g., complete heart block, ventricular tachycardia) - atrium contracts against closed tricuspid valve. - Large 'v' waves: tricuspid regurgitation. - Hepatojugular reflux: sustained pressure on the liver causes a rise in JVP (>3 cm) sustained for >15 seconds, indicating right heart failure or volume overload when the right ventricle cannot accommodate increased venous return.

JVP is distinguished from carotid pulsation by its biphasic waveform, non-palpability, decrease with inspiration (usually), and changes with position/Valsalva.