Sandbox: Pulmonary Valve regurgitation

Epidemiology and Demographics

• The prevalence of mild pulmonary regurgutation is present in 40% to 78% of patients with normal pulmonary valve anatomy.
• In patients born with congenital heart disease, 20% of patients have associated abnormalities of the pulmonary valve or the right ventricular outlet obstruction.

Classification

Based on the pulmonary Valve Morphology
Pulmonary Regurgitation is classified into primary and secondary types based on the involvement of the pulmonary Valve.

• Primary Pulmonary Regurgitation:The pulmonary valve morphology is affected. Isolated PR is very rare and is most commonly associated with other congenital heart diseases.
• Secondary or Functional Pulmonary Regurgitation: The pulmonary valve function is normal. Conditions such as pulmonary hypertension and PA aneurym cause dilation of the valve annulus leading to regurgitation.

Based on the Severity
Pulmonary regurgitation is classified into three categories based on the severity of the regurgitant jet demonstrated on the 2D echo.

Natural History, Prognosis, Complications

Natural History

• Mild PR is a very common finding on 2D echo.
• Majority of patients with mild PR are asymptomatic and have a beningn course, not progressing to chronic PR.
• Patients tolerate severe chronic PR for a long period of time and begin to develop symptoms when the right ventricle function begins to decline.
• Chronic severe PR leads to progressive dilation and systolic dysfunction of the right ventricle resulting in symptoms.
• Patients with acute worsening of PR should be evaluated for associated conditions such as pulmonary hypertension which increase the pressure gradient.

Prognosis

• Symptomatic patients are treated with pulmonary valve replacement and have a good prognosis.

Complications

• Progressive right ventricular dilation increases the risk of ventricular arrhythmias and sudden cardiac death. Patients with tetralogy of Fallot are at increased risk of developing these complications compared to patients with isolated PR.

Pathophysiology

• Patients with PR develop chronic right ventricular overload resulting in right ventricular remodelling and progressive decline in function.
• Progressive dilation of the right ventricle results in functional tricuspid regurgitation and increases the risk of developing arrhythmias.
• The rate of decline in right ventricular systolic function is affected by associated conditions such as peripheral pulmonary artery stenosis and pulmonary hypertension which further increase the severity of pulmonary regurgitation.
• In patients with increased pulmonary artery pressure from dysfunction of LV or residual pulmonary artery stenosis increases the severity of PR.
• The severity of regurgitant jet is dependent on:
  • Size of the regurgitant orifice
  • Afterload of the RV
  • RV diastolic complaince
  • Duration of RV diastole According to 2014, ACC/AHA valvular heart disease guidelines the stages of severe pulmonary regurgitation are described as follows:

Stage	Definition	Pulmonary Valve Anatomy	Valve Hemodynamics	Hemodynamic Consequences	Symptoms
C,D	Severe PR	Distorted or absent leaflets Annular dilation	Color jet fills RVOT CW jet density and contour: dense laminar flow with steep deceleration slope; may terminate abruptly	Paradoxical septal motion (volume overload pattern) RV enlargement	None or variable and dependent on cause of PR and RV function

Causes

The most common causes of pulmonary regurgitation are following repair of tetralogy of Fallot and pulmonary stenosis. Other common causes include as follows:

Congenital Causes	Acquired Causes	Chronic PR	Acute PR
Quadricuspid or Bicuspid valves Hypoplasia of the valves Prolapse of the pulmonary valve	Infective endocarditis Following transannular patching for tetralogy of Fallot Post repair of pulmonary valve stenosis Rheumatic heart disease Carinoid Syndrome Myxomatous Degeneration of the pulmonary valve.	Following transannular patching for tetralogy of Fallot Following balloon or surgical valvulotomy or valvuloplasty for pulmonary stenosis Absent pulmonary valve syndrome Isolated congenital PR Peripheral pulmonary artery stenosis Pulmonary hypertension Right ventricular outlet aneurysm	Neonatal Ebstein’s anomaly Following balloon dilation of critical pulmonary stenosis Perforation of valvar pulmonary atresia

Diagnosis

History and Symptoms

Clinical presentation of pulmonary regurgitation varies on the severity of the regurgitation and the right ventricular function.

• Isolated pulmonary regurgitation is usually asymptomatic and is an incidental finding on 2D echo even when the regurgitation is severe.
• Patients with chronic PR develop right heart failure and present with the following symptoms:
  • Intitial symptom of chronic PR is functional limitation of physical activity
  • Ankle edema or swelling of the feet and legs
  • Dyspnea on exertion
  • Fatigue
  • Hemoptysis or frothy sputum
  • Nocturnal cough
  • Palpitations or extra heart beats
• Patients with arrythmias present with palpitations, dizziness, or an episode of syncope.

Physical Examination

The physical examination findings in significant pulmonary regurgitation include:

• Soft diastolic, decrescendo murmur best heard in the left upper sternal region which increases in intensity with inspiration.
• It can accompanied by a systolic ejection murmur.
• Right ventricular heave is present when the right ventricle is enlarged.

Echocardiography

It is the initial imaging diagnostic test to study the pulmonary valve, RVOT anatomy, to identify the presence and quantify the severity of PR. The findings include:

• In adults, visualization of the pulmonary valve is obtained from the parasternal short-axis view at the level of the aortic valve or from a subcostal approach.
• Pulmonary valve morphology anomalies such as bicuspid or quadricuspid valves, hypoplasia, dysplasia, absence of pulmonary valve and motion abnormalities can be detected.
• PR is diagnosed my demonstrating a diastolic jet in the RV outflow tract towards the RV.

Colour Flow Doppler

The findings suggestive of significant PR include:

• A narrow small central and spindle shaped regurgitant jet is seen in mild PR.
• In severe PR a wide diastolic jet at the origin which occupies 65% of the the RVOT width is seen on colour doppler imaging. The duration of the jet increases with increasing severity of PR.
• In severe PR, a rapid equalization of diastolic pressures between the pulmonary artery and RV occurs, resulting in a short-lived regurgitant jet which can mislead in diagnosis of the severity of PR.
• In patients with chronic significant PR, dilation of the RV can be demonstrated. In patients with physiologic PR and acute PR RV dimensions are normal.

Vena Contracta Width

It is a more accurate method to assess the severity of PR, but it lacks validation studies.

Flow convergence method

It can be assessed in few patients but lacks validation studies.

Pulsed Doppler

It is useful to assess the forward and regurgitant flows at the pulmonary annulus and the pulmonary artery, which can be used to calculate the regurgitant volume and regurgitant fraction.

Spectral Doppler

The density of the CW signal provides a qualitative measure of regurgitation.

• Pressure half-time (PHT) of less than 100 ms has a high sensitivity and specificity for identifying hemodynamically significant PR in congenital heart disease.
• PR Index: It is a ratio expressed between the duration of PR and total diastole which is measured from the end of forward pulmonary flow to the beginning of the next forward pulmonary flow curve. It has shown to have equal sensitivity to determine the severity of PR when compared to CMR.
• Myocardial performance index Tei index determined by tissue doppler imaging is a sensitive indicator of RV function in patients with chronic PR.

Exercise Echocardiography

It is used to unmask latent RV dysfunction and is a helpful investigation to assess the RV function in patients who have underwent an intervention for significant PR.

Determination of severity of PR based on the findings on echocardiography:

Parameters	Mild	Moderate	Severe
Pulmonic valve morphology	Normal	Normal or abnormal	Abnormal
Colour flow PR jet width	Small, usually 10 mm in length with a narrow origin	Intermediate	Large, with a wide origin Can be brief in duration due to the equalization right ventricular and pulmonary diastolic pressures
Continous wave signal of PR jet	Faint/slow deceleration	Dense/variable	Dense/steep deceleration, early termination of diastolic flow
Pulmonic vs. Aortic flow by pulse wave	Normal or slightly increased	Intermediate	Greatly increased

EKG

• EKG findings in chronic PR are non specific.
• In patients with tetralogy of Fallot increased QRS duration with widened QRS complex reflects the severity of PR and right ventricular dilation predisposing the patients to develop malignant arrythmias.
• In patients with RV volume overload and isolated PR, QRS prolongation with rSr morphology can be seen in right precordial leads.
• RBB is common in majority of patients who have tetralogy of Fallot repair with right ventriculotomy.

Chest X-Ray

Chest X-Ray in chronic PR the following findings can be demonstrated:

• Cardiomegaly when there is dilation of the RV
• Pulmonary artery dilation

Cardiac MRI

Cardiac magnetic resonance(CMR) is a gold standard for assessment of morphology of the pulmonary valve, for quantification of the severity of the regurgitation and the RV systolic function.

• CMR is useful in quantification of the regurgitant volume and regurgitant fraction of PR by using sequences called “velocity- encoded phase-contrast images”.
• CMR is useful for evaluating pulmonary regurgitant fraction, RV end-diastolic and end- systolic volumes, and RV ejection fraction
• CMR is the diagnostic modality preffered to determine the requirement of reintervention in patients with repaired tetralogy of Fallot and to assess the ventricular function and dimensions.

Cardiac Catheterization

Echo and CMR the investigations of choice in patients to detect and diagnose the severity of PR. Cardiac Catheterization is not a recommended for diagnosis of PR.

Treatment

Surgical Options

Recommendations for Surgery for Adults With Previous Repair of Tetralogy of Fallot

• Class I: Pulmonary valve replacement is indicated for severe pulmonary regurgitation and symptoms or decreased exercise tolerance. (Level of Evidence: B)
• Class IIa : Pulmonary valve replacement is reasonable in adults with previous tetralogy of Fallot, severe pulmonary regurgitation, and any of the following:
  • Moderate to severe RV dysfunction. (Level of Evidence: B)
  • Moderate to severe RV enlargement. (Level of Evidence: B)
  • Development of symptomatic or sustained atrial and/or ventricular arrhythmias. (Level of Evidence: C)
  • Moderate to severe TR. (Level of Evidence: C)