Medicine Marrow Pg 371-375 (Cardiology)

x Descent

• Occurs during atrial relaxation in diastole
• A prominent x descent is seen in constrictive pericarditis (CCP) and cardiac tamponade (CT)
• A reduced or absent x descent is seen in right ventricular failure (RVF), tricuspid regurgitation (TR), and atrial fibrillation (AF)

V Wave

• Occurs during atrial filling, primarily in systole, just before the peak of the v wave
• A prominent v wave is often caused by increased right atrial volume during ventricular systole
  • Common causes include:
    • Tricuspid regurgitation (TR)
    • Cor pulmonale
    • High superior vena cava pressure due to RVF
    • Right ventricular hypertrophy
    • Atrial septal defect (ASD) with mitral regurgitation (MR)
• A reduced v wave is seen in states of hypovolemia and hypotension

a Wave

• Represents atrial contraction in diastole, just before systole
• Precedes the upstroke of the carotid pulse and follows the P wave of the ECG
• A large a wave is indicative of the atria contracting against resistance
  • Common causes include:
    • Right ventricular hypertrophy
    • Right ventricular hypertrophy
    • Tricuspid stenosis (TS)
    • Right atrial myxoma
    • Pulmonary hypertension
• A giant a wave (Cannon a wave) is caused by the atria contracting against a closed tricuspid valve
  • In regular rhythms, this is seen in:
    • Atrioventricular nodal reentrant tachycardia (AVNRT)
    • Atrioventricular reentrant tachycardia (AVRT)
  • In irregular rhythms, this is seen in:
    • Ventricular tachycardia with atrioventricular dissociation
    • Complete heart block (CHB)
• An absent a wave is seen in:
  • Atrial fibrillation (AF)
  • Hyperkalemia (increased serum potassium)

c Wave

• Represents the upward bulge of the tricuspid valve during isovolumetric contraction and coincides with the first heart sound (S₁)

Y Descent

• Represents right atrial emptying, leading to a decrease in right atrial pressure
• Occurs in diastole, following the opening of the atrioventricular valve
• A rapid y descent is seen in constrictive pericarditis, also known as Friedreich’s sign
  • It is seen in conditions causing prominent V wave.
• A slow y descent is seen in:
  • Tricuspid stenosis (TS)
  • Right atrial myxoma
  • Impaired right atrial emptying and right ventricular filling

h Wave

• A small wave that appears just prior to the a wave in long diastole due to a decreased heart rate

Other Important Information

• Aortic stenosis (AS), aortic regurgitation (AR), and mitral regurgitation (MR) usually do not cause changes in JVP
• Mitral stenosis (MS) causes a prominent a wave due to pulmonary hypertension
• A Jugular Venous Pressure (JVP) greater than 3 cm above the sternal angle is considered elevated
• Right atrial pressure is calculated by adding 5 to the JVP height in centimeters (cm H₂O)
• A right atrial pressure greater than 8 cm H₂O is considered elevated
• Right ventricular end-diastolic pressure is equal to right atrial pressure

Causes of Elevated JVP

• A pulseless rise in JVP is indicative of superior vena cava obstruction. All other causes lead to a pulsatile rise.
• Circulatory overload can cause an elevated JVP and is seen in:
  • Renal failure
  • Liver cirrhosis
  • Excessive fluid administration
• Increased right ventricular pressure and decreased compliance can lead to an elevated JVP and is seen in:
  • Pulmonary stenosis
  • Pulmonary hypertension
  • Right ventricular failure/right ventricular hypertrophy
  • Right ventricular infarction
• Right ventricular inflow impedance can cause elevated JVP and is seen in:
  • Tricuspid stenosis (TS)/atresia
  • Right atrial myxoma
  • Chronic constrictive pericarditis

Kussmaul's Sign

• An increase in JVP with inspiration
• Indicative of:
  • Constrictive pericarditis (CCP)
  • Tricuspid stenosis (TS)
  • Restrictive cardiomyopathy (RCM)

Abdominojugular Reflex (AJR)

• Previously known as the Hepatojugular reflex
• Performed by compressing the periumbilical region for 10 seconds
• A rise in JVP during the procedure suggests impending right heart failure
• The principle is that abdominal compression increases venous return, which a faulty or dilated right ventricle cannot accommodate without a rise in pressure.

Measurement of JVP

• The patient should be positioned at a 45° angle
• Use a ruler to measure the highest point of JVP
• Measure perpendicular to the ruler at the sternal angle
• The sternal angle is 5 cm above the center of the right atrium

Difference between IJV and Carotid Pulses

• The Internal Jugular Vein (IJV) pulse is superficial and lateral in the neck, while the carotid pulse is deeper and medial
• The IJV pulse is better seen than felt, while the carotid pulse is better felt than seen
• The IJV pulse has 2 peaks and 2 troughs, while the carotid pulse has a single upstroke
• Descents are more obvious in the IJV pulse, while the carotid pulse has a brisker and visible upstroke
• Digital compression abolishes the IJV pulse, while it has no effect on the carotid pulse
• The IJV pulse falls during inspiration, while the carotid pulse does not change with respiration
• Abdominal compression elevates the IJV pulse, but has no effect on the carotid pulse

Waveform Components

• The waveform has 3 positive waves: "a," "c," and "v"
• It also has 3 descents: "x descent," "y descent"

Inference

• A JVP greater than 3 cm above the sternal angle is elevated
• Right atrial pressure is estimated using the formula: (5 + JVP height in cm) cm H₂O
• A right atrial pressure greater than 8 cm H₂O is considered elevated