Pulmonary Regurgitation Disorders

Overview

Anatomy

Pulmonary or pulmonic valve:

• Semilunar valve between the right ventricle (RV) and pulmonary artery (PA)
• Consists of 3 cusps: anterior, left, and right
• Opens during systole as the RV pressure exceeds the pulmonary trunk pressure
• Closes during diastole as the RV pressure drops (S2), preventing retrograde flow from the pulmonary trunk

Epidemiology and Etiology

Definition

• Abnormal backflow of blood through the pulmonic valve into the RV during ventricular diastole
• Trace or mild (physiologic) pulmonic regurgitation (PR) found commonly in normal individuals

Epidemiology and Etiology

• PR found in 30% of patients who underwent surgical correction of congenital cardiac anomalies
• Typically, present by 30–40 years of age
• Congenital PR is rare.
• Causes:
  • Post-surgical treatment or after pulmonic balloon valvotomy of pulmonary stenosis (PS) in children (most common cause of severe PR)
  • Carcinoid (usually mixed pulmonic valve disease with PR and PS)
  • Dilation of the pulmonic valve ring from chronic severe pulmonary hypertension 
  • Endocarditis
  • Marfan’s syndrome

Pathophysiology and Clinical Presentation

Pathophysiology

• PR stems from the following abnormalities:
  • Abnormalities in valve morphology
  • Dilation of the pulmonic valve ring
  • Congenitally absent or malformed valve
• With PR, the backflow causes increased preload and afterload.
• RV overload → RV enlargement to compensate for the increased volume → RV dysfunction (tricuspid regurgitation (TR) may follow)
• RV dysfunction eventually leads to ↓ cardiac output → ↑ heart rate to maintain tissue oxygenation → symptoms of exercise intolerance due to increased oxygen demand.
• Complications: RV failure, thromboembolic events, hepatic congestion, arrhythmias

Symptoms

• Commonly asymptomatic during mild to moderate disease
• Severe PR: 
  • Fatigue, exertional dyspnea, palpitations, syncope
  • With associated TR and RV failure: hepatic congestion, ascites, peripheral edema

Signs

• Increased jugular venous pressure (JVP)
• Graham-Steell murmur: 
  • Hallmark of PR
  • High-pitched, decrescendo diastolic murmur heard best at the 2nd left intercostal space at the sternal border (from ↑ RV stroke volume)
  • Increases with inspiration
  • Diminishes with Valsalva maneuver
  • Split S2 with loud P2, and an RV lift (from RV enlargement)

Diagnosis and Management

Diagnosis

• Transthoracic echocardiogram (TTE) with Doppler:
  • Assessment of pulmonic valve morphology and function
  • Detects severity of PR, which is determined by jet width and duration
  • Severe PR: The regurgitant jet fills the RV outflow tract (> 50% pulmonary valve annulus width).
  • Also shows RV enlargement, systolic dysfunction
• Electrocardiogram (ECG):
  • Right ventricular hypertrophy 
  • Right axis deviation 
  • Right atrial (RA) enlargement (P pulmonale)
  • Arrhythmias from RV dilation
• Chest X-ray:
  • Prominent PA
  • RA and RV enlargement
• Exercise testing:
  • Can detect exercise-induced arrhythmias
  • Evaluates exertional symptoms to help decide need for valve replacement

• Cardiac magnetic resonance imaging: 
  • Helps assess RV size and function 
  • Evaluates severity of PR by quantifying the regurgitant jet
• Cardiac catheterization:
  • Not necessary for diagnosis
  • Used in evaluating pulmonary vascular resistance and preoperative coronary artery disease assessment

Management

• Monitoring:
  • Annual examination and echocardiography
  • Those with repaired tetralogy of Fallot or who have undergone balloon valvotomy need at least a yearly cardiology check-up.
• Medical therapy:
  • Associated heart failure: diuretics, angiotensin converting enzyme inhibitors
  • Endocarditis prophylaxis: with history of infective endocarditis
• Surgical pulmonary valve replacement:
  • Symptomatic patients
  • Mild or moderate RV or left ventricular systolic dysfunction
  • Severe RV dilation
  • RV systolic pressure due to RV outflow tract > ⅔ of systemic pressure
  • Progressively reduced exercise tolerance
• Anticoagulation:
  • For patients with mechanical valve prosthesis
  • Temporary (3–6 months) for patients with bioprosthetic valves

Clinical Relevance

• Tetralogy of Fallot (TOF): cyanotic congenital heart disease characterized by the tetrad of RVH, an overriding aorta, pulmonary valve stenosis, and a ventricular septal defect. Surgically corrected TOF is a common cause of subsequent pulmonary regurgitation.
• Ventricular septal defect: a common heart defect that allows passage of blood from the high-pressure left ventricle to the lower-pressure right ventricle. Ventricular septal defect produces a holosystolic murmur in the left 3rd and 4th interspaces along the sternum. Pulmonary hypertension can occur, resulting in high-pressure pulmonary valve regurgitation. 
• Pulmonary hypertension: a heterogeneous condition of high blood pressure in the pulmonary vasculature that could be idiopathic (without underlying lung or cardiac disease) or from secondary causes. Pulmonary hypertension may lead to PR and right heart abnormalities.
• Carcinoid syndrome: small, slow-growing neuroendocrine tumors. The tumors are associated with unregulated vasoactive hormone production, inducing development of fibrous endocardial plaques and leading to pulmonic and tricuspid valve abnormalities.
• Rheumatic fever: a late complication of untreated streptococcal pharyngeal infection characterized by valvular abnormalities, most commonly of the left heart. While rare, the pulmonic valve can be affected concurrently with the mitral valve.