What is Kussmaul sign?

Kussmaul Sign

Kussmaul sign is defined as a paradoxical rise in jugular venous pressure (JVP) during inspiration, in contrast to the normal physiological fall in JVP that occurs during inspiration. 1

Clinical Significance

• Kussmaul sign is an important physical examination finding that can be observed in several cardiovascular conditions, particularly those affecting right heart function 1
• It serves as a diagnostic clue for constrictive pericarditis, where it is frequently present and helps differentiate it from restrictive cardiomyopathy 1
• The presence of Kussmaul sign indicates abnormal hemodynamics, specifically impaired right ventricular filling during inspiration 1

Conditions Associated with Kussmaul Sign

• Constrictive pericarditis: Kussmaul sign is a classic finding and important diagnostic criterion 1
• Right ventricular infarction: The clinical triad of hypotension, clear lung fields, and elevated JVP (including Kussmaul sign) is characteristic 1
• Heart failure: Associated with adverse cardiopulmonary hemodynamics and poorer clinical outcomes 2, 3
• Cardiac tamponade: Often accompanied by other signs like pulsus paradoxus 4
• Diabetic ketoacidosis: May be observed along with other signs of dehydration 1

Pathophysiology

• In normal physiology, inspiration creates negative intrathoracic pressure that enhances venous return to the right atrium, causing JVP to decrease
• In conditions with impaired right ventricular filling or compliance:
  • Inspiration increases venous return to the right heart
  • The right ventricle cannot accommodate this increased volume
  • This leads to increased right atrial pressure during inspiration (paradoxical rise) 2
• In constrictive pericarditis, the rigid pericardium prevents normal cardiac chamber expansion during inspiration, resulting in the paradoxical rise in JVP 1

Clinical Assessment

• Best observed by examining the internal jugular vein with the patient positioned at a 45-degree angle 1
• A simplified approach involves observing if the JVP is visible above the right clavicle in the sitting position, both at rest and during inspiration 5, 3
• The presence of Kussmaul sign during inspiration, even when JVP is not elevated at rest, carries prognostic significance in heart failure patients 5, 3

Prognostic Value

• In heart failure patients, Kussmaul sign is associated with:
  • Higher pulmonary pressures and lower cardiac index 2
  • Greater neurohormonal activation 2
  • Higher incidence of post-transplant right ventricular failure 2
  • Increased mortality and rehospitalization rates 5, 3
• The presence of Kussmaul sign carries prognostic significance regardless of whether patients have heart failure with reduced or preserved ejection fraction 3

Clinical Pearls

• Kussmaul sign should be distinguished from pulsus paradoxus (an exaggerated decrease in systolic blood pressure during inspiration), though both may coexist in conditions like cardiac tamponade 6
• When evaluating patients with suspected right heart pathology, always assess for Kussmaul sign as it provides valuable diagnostic and prognostic information 1, 2
• The finding of Kussmaul sign should prompt further evaluation with appropriate imaging studies such as echocardiography, CT, or cardiac MRI to determine the underlying cause 1