Pulmonary regurgitation

Pulmonary regurgitation involves the backflow of blood from the pulmonary artery across the pulmonary valve.

In pulmonary regurgitation (PR), blood flows backwards from the pulmonry artery across the pulmonary valve and into the right ventricle during diastole.

PR can be classified as physiological, primary, or secondary:

• Physiological: a mild degree of PR in patients with otherwise healthy hearts. Physiological PR is relatively common and does not cause any symptoms or problems.
• Primary: PR caused by problems with the pulmonary valve itself.
• Secondary: PR caused by problems elsewhere in the cardiovascular system, with knock-on effect on the pulmonary valve.

Overall, diseases of the pulmonary valve are rare.

Pulmonary regurgitation has a bimodal age-incidence curve, reflecting its two most common causes:

1. A peak in young patients, who present with PR as a congenital defect, or who develop PR following surgery in early life to correct a congenital PR defect.
2. A peak in older patients (roughly 50-60) who present with PR because of pulmonary hypertension.

Causes of primary PR may be iatrogenic or congenital, or secondary to infection, carcinoid, or rheumatic fever.

Primary PR

The main causes of primary PR include:

• Iatrogenic: most common cause of severe PR, which can complicate any proceure around the right ventricular outflow tract (e.g. Treating congenital cardiac disorders, balloon valvuloplasty, valvotomy)
• Congenital: these are rare and most commonly seen in patients with tetralogy of Fallot
• Infection (e.g. Infective endocarditis – especially in intravenous drug users).
• Rheumatic heart disease
• Carcinoid disease

Secondary PR

Secondary PR is usually secondary to an increase in pulmoinary arterial hypertension.

• Severe pulmonary artery hypertension
• Pulmonary artery dilatation

The main underlying problem is backflow of blood from the pulmonary trunk into the right ventricle during diastole.

In PR, the backflow of blood across the valve leads to right ventricular overload. The right ventricle has to pump more blood with each heartbeat; the blood delivered from the right atrium, plus the regurgitant blood.

In response to the increased work, the right ventricle undergoes hypertrophy and enlarges. Initially this helps it cope, and pulmonary regurgitation can be tolerated for many years. Eventually the right ventricle may fail, undergoing dilatation, and become dysfunctional. As we observe in tricuspid regurgitation, any cause of right ventricular dilatation can affect tricuspid valve function.

Patients with pulmonary regurgitation are usually asymptomatic for many years.

Prior to right ventricular dysfunction (i.e. until PR becomes severe), patients with PR are usually asymptomatic. As the right ventricle starts to fail and dilate symptoms may develop. Features of severe PR with decompensated right ventricular function would be those of right heart failure.

History

• Fatigue
• Exertional dyspnoea
• LIght-headedness, palpitations, and/or syncipe (more susceptible to arrhythmias as ventricle dilates)

Examination

Clinical signs associated with PR can include:

• Parasternal heave: a palpable prolonged “lifting” of the chest wall with each heartbeat. Commonly due to right ventricular hypertrophy and best felt with the heel of the hand placed on the patient's chest.
• Diastolic murmur: loudest in the pulmonary area (i.e. 2nd intercostal space, left sternal edge)
• Features of right heart failure: raised JVP, periphral oedema, hepatomegaly

NOTE: features of right heart failure are particularly likely to be present if tricuspid regurgitation develops.

The murmur of PR depends on whether pulmonary hypertension is present. If present, it is known as a Graham-Steell murmur. This is a high-pitched, early diastolic murmur with a decrescendo quality. It may be pandiastolic depending on the pressure gradient between the pulmonary artery and right ventricle. The murmur sounds similar to aortic regurgitation.

Three factors help differentiate pulmonary regurgitation from aortic regurgitation:

1. PR will be louder in inspiration (“RILE”)
2. PR should be louder in the pulmonary auscultation area (as opposed to the aortic area).
3. There will be no collapsing pulse in PR.

In the absence of pulmonary hypertension, there will be less of a pressure gradient for regurgitation during diastole. As such, the murmur may be inaudible. If present, it will be lower pitched and may be brief, since the pressure will equalise more quickly between the pulmonary artery and right ventricle during diastole.

Echocardiography is the best diagnostic tool for valvular heart disease.

Echocardiography can be used to diagnosis pulmonary valve disease (both stenosis and regurgitation), and will help to determine its severity.

Grading the severity of PR uses multiple echocardiographic measurements and is beyond the scope of a non-specialist.

Other incidental findings on chest x-ray or electrocardiogram that can point to PR include:

• CXR: Enlarged right ventricle if the PR is severe.
• ECG: If right ventricular hypertrophy is present, there may be right axis deviation and ECG features of RV hypertrophy.

The management of pulmonary regurgitation depends on whether it is primary or secondary, and whether patients are symptomatic.

Any patients with secondary PR (i.e. due to a separate pathology) should be treated for the underlying pathology (e.g. treatment for underlying pulmonary hypertension).

Asymptomatic

The management of PR will depend on whether the patient presents with symptoms. Any degree of PR (i.e. mild, moderate, severe) without symptosm and normal right ventricular function does not need treatment.

Patients with moderate or severe PR should be followed up annually to monitor for new signs or symptoms, or changes to their echocardiograms.

Symptomatic

In patients with severe PR who have symptoms, evidence of right heart failure, or co-existing valve disease, then surgical intervention is first line. This can include:

• Surgical valve replacement (preferred).
• Percutaneous replacement

Patients usually do well following pulmonary valve surgery. In those unsuitable for surgery, medical therapy can be used including diuretics and ACE inhibitors. However, left untreated, severe pulmonary regurgitation usually progresses to right heart failure and/or arrhythmia, and will eventually be fatal.

Last updated: September 2024

References:

• UpToDate. Pulmonic regurgitation.

• UpToDate. Auscultation of cardiac murmurs in adults.

• Sharma, R. et al. Pulmonary valve regurgitation. Reference article, Radiopaedia.org (Accessed on 17 May 2024) https://doi.org/10.53347/rID-57549