JVP — MRCS Part B Applied surgical science and critical care

An elderly man in heart failure, three days after a hemicolectomy, becoming breathless with effusions. The station uses him to examine the jugular venous pressure and its waveform.

Which vein and why

The internal jugular vein. It runs in a straight line with the right atrium through the superior vena cava, without valves, so its height and pulsation reflect right atrial pressure directly. The external jugular is superficial and easier to see but has valves and passes through fascia that can kink it, so its level is unreliable, though it is used when the internal jugular cannot be found.

What it shows

Right atrial pressure, and through that right ventricular filling. Measured as the vertical height of the top of the pulsation above the sternal angle with the patient at 45 degrees; normal is up to 3–4 cm, about 8 cm above the atrium. It is distinguished from the carotid by its double waveform, its fall on inspiration and on sitting up, its rise on pressing the abdomen, and by being impalpable and easily obliterated.

Causes of a raised JVP

Right heart failure, fluid overload, pulmonary hypertension and pulmonary embolism, tricuspid disease, constrictive pericarditis and cardiac tamponade, superior vena caval obstruction (non-pulsatile), and a tension pneumothorax.

The waveform

The a wave is atrial contraction; the c wave is the tricuspid valve bulging back into the atrium as the ventricle starts to contract; the x descent is the atrium relaxing and the valve ring being pulled down during systole; the v wave is the atrium filling against a closed valve; the y descent is the valve opening and the atrium emptying into the ventricle.

Changes in disease

Atrial fibrillation: no a waves, because there is no coordinated atrial contraction. Complete heart block: intermittent giant “cannon” a waves when the atrium contracts against a closed tricuspid valve. Tricuspid stenosis: large a waves from contraction against the narrowed valve, with a slow y descent. Tricuspid regurgitation: large v waves that merge with the c wave and a sharp y descent.

Respiration and Kussmaul's sign

Inspiration lowers intrathoracic pressure, draws blood into the chest and lets the right atrium fill more easily, so the JVP falls. When the right heart cannot accept the extra return — constrictive pericarditis, restrictive cardiomyopathy, right ventricular infarction, sometimes tamponade — the JVP rises on inspiration instead: Kussmaul's sign.

Managing this patient

Sit him up, give oxygen, assess with an ECG, chest radiograph, gases, troponin and electrolytes, and treat as acute heart failure: intravenous loop diuretic, nitrate if the blood pressure allows, and continuous positive airway pressure if he tires. Stop the intravenous fluids, catheterise and chart the balance, and rule out the postoperative causes that mimic it — pulmonary embolism, pneumonia, a myocardial infarction — before settling on fluid overload as the whole answer.