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.

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

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 arrythmias.
• 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.

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 Post repair of tetralogy of Fallot Post repair of pulmonary valve stenosis Rheumatic heart disease Carinoid Syndrome Myxomatous Degeneration of the pulmonary valve.	Following repair of 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.

2D Echo

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 suggestive of PR 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.
• PR is diagnosed my demonstrating a diastolic jet in the RV outflow tract towards the RV.
• Determinants of assessing severity of PR include:
  • Size of the regurgitant orifice
  • Hydraulic impedance/afterload
  • Ventricular diastolic compliance
  • Diastolic filling time
• 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 and flow convergence method are more accurate methods to detect regurgitant severity when compared to than colour flow imaging, but guidelines for assessment of severity are yet to be described.
• Exercise echocardiography can be used to unmask latent RV dysfunction, it is a helpful investigation to assess the RV function in patients who have underwent intervention for significant PR.

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 involving the right sided chambers.
• Pulmonary artery dilation