Pulmonary regurgitation

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Pulmonary regurgitation (PR) or insufficiency is a valvular heart disease characterized by an incomplete closure of the pulmonary valve leading to a diastolic reflux into the right ventricle. The malcoaptation of the cusps can be caused by a primary disease of the valve or by the dilation of the pulmonary trunk.

Contents

Pathophysiology

Pulmonary Regurgitation results in right ventricle volume overload which eventually leads to right ventricular enlargment and dysfunction; the augmented stroke volume may lead to secondary dilation of the pulmonary main artery which in turn increases the degree of regurgitation. Normally PR is well tollerated for many years, but right ventricle function progressively worsens and may lead to right heart failure. If the PR is secondary to pulmonary hypertension, clinical symptoms and prognosis are secondary to the grade of the hypertension rather than the rugurgitant volume. The entity of the regurgitant volume depends on numerous factors: dimension of the orifice, filling time, diastolic gradient between pulmonary artery and right ventricle and the respective compliances[1]. In severe pulmonary regurgitation we may find equalization of diastolic pressures without significant diastolic reflux.

Aetiology

Diseases of the valve

  • The commonest causes of isolated pulmonary regurgitation are congenital abnormalities of the valve: bicuspid or quadricuspid valve, hypoplasia of the cusps, perforation of an atresic valve, myxomatous valve prolapse.
  • Unlike other valves, inflammatory and infective processes (like endocarditis, rehumatic heart disease or rehumathoid arthritis ) rarely involve the pulmonary cusps.
  • Bowel carcinoid tumors may affect the pulmonary and the tricuspid valves: it usually causes a fibrosis with retraction and reduced mobility of the cusps/leaflets with a clinical aspect of steno-insufficency with predominant regurgitation[2].
  • Marfan’s syndrome.
  • Cardiac trauma.
  • As a consequence of surgical of percutaneous intervention of balloon valvuloplasty on a pulmonary stenosis.
  • As a consequence of surgical intervention on the right heart (e.g. post-repair of Fallot's Tetralogy).

Dilation of the pulmonary artery

Echocardiographic assesment of regurgitation

A mild, functional, PR is present in the majority of normal subjects and decreases in proportion with age. Physiological regurgitant jets are usally small, central, protodyastolic or mid-dyastolic, not longer than 2 cm at the color flow imaging and with a peak velocity <1.5 m/s at continous wave doppler quantification[3]. The determination of pulmonary insufficiency degree is not supported by robust data. Following parameters are presenting according to european reccomendations[1] [4].

Pulmonic Valve Morphology

Visualization of the valve is obtained by parasternal short-axis view at the level of the aortic valve or from a subcostal approach. It could provide information on number, motion and structure of the cusps; flail valve is specific for severe regurgitation.

Color flow Doppler

Useful to evaluate the spatial orientation of the jet (central, eccentric) The duration of the jet tends to be longer in more important regurgitation even if may be inaccurate in severe PR because of the early equalization of pressures between right ventricle and pulmonary artery. The diameter of the jet evaluated in diastole immediately below the valve may be significant for a severe regurgitation if it occupies >65% of the RVOT. The vena contracta width and the EROA values are not yet defined because of the lack of validated studies. Three-dimensional evaluation of vena contracta is expected to provide a more accurate assessment of PR; it has been suggested that a regurgitant volume >115 ml is in favor of a severe PR[5]. PISA method is difficult to perform and currently lacks of validation. However it could provide a quantitative assesment of volume regurgitation.

Pulsed Doppler

The evaluation of forward and reverse flow across the pulmonary valve and the pulmonary artery is not yet validated. The presence of a markedly increase in pulmonic/aortic flow ratio suggests a relevant regurgitant volume.

Continous Wave Doppler

The density of the signal may provide a qualitative measurement of the regurgitation while a steep deceleration of the doppler spectrum or an early termination of diastolic regurgitant flow might be a sign of severe PR; however these findings are not specific.

Right ventricle size

The presence of a dilation of right ventricle is not specific for severe PR. However, the presence of a normal RV size suggests a not hemodinamically important regurgitation. These considerations are not relevant in case of pulmonary hypertension, in complex congenital heart diseases and after surgical repair.

References

  1. D’angelo G et al. Malattie della valvola tricuspide e polmonare in: Nicolosi, GL. Manuale di ecocardiografia clinica. Ed. Piccin, 2008.
  2. Dumaswala B, Bicer EI, Dumaswala K, Donmez C, Bhagatwala KD, Karia N, McKay J, Joshi D, Sadat K, Nanda NC. Live/real time three-dimensional transthoracic echocardiographic assessment of the involvement of cardiac valves and chambers in carcinoid disease. Echocardiography. 2012 Mar;29(3):E72-7. doi: 10.1111/j.1540-8175.2011.01662.x.
  3. Yoshida K, Yoshikawa J, Shakudo M, Akasaka T, Jyo Y, Takao S, Shiratori K, Koizumi K, Okumachi F, Kato H, et al. Color Doppler evaluation of valvular regurgitation in normal subjects. Circulation. 1988 Oct;78(4):840-7.
  4. Lancellotti P et al. European Association of Echocardiography reccommendations for the assessment of valvular regurgitation. Part 1: aortic and pulmonary regurgitation (native valve disease). Eur J Echocardiogr. 2010 Apr;11(3):223-44.
  5. Pothineni KR, Wells BJ, Hsiung MC, Nanda NC, Yelamanchili P, Suwanjutah T, Prasad AN, Hansalia S, Lin CC, Yin WH, Young MS. Live/real time three-dimensional transthoracic echocardiographic assessment of pulmonary regurgitation. Echocardiography. 2008 Sep;25(8):911-7.
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