Pulmonic regurgitation pathophysiology: Difference between revisions

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==Overview==
==Overview==
[[Pulmonary valve]] is located at the junction of the [[Ventricular outflow tract|right ventricular outflow tract]] and [[pulmonary artery]]. Three equal-sized, semilunar cusps or leaflets make up the [[pulmonary valve]]. [[Pulmonary valve]] opens during right ventricular [[systole]] and closes during right ventricular [[diastole]]. [[PR|Pulmonary regurgitation]] (PR) may be caused by an acquired alteration in the valvular morphology, idiopathic dilatation of the pulmonary artery (IDPA), congenital absence or malformation of the pulmonary valve|valve]], and increasing regurgitation causing [[right ventricle|right ventricular]] volume overload. The pathophysiologic mechanism of [[pulmonic regurgitation]] includes [[right ventricular overload]] resulting in the right [[ventricular remodeling]] and progressive decline in function. The rate of decline in right ventricular [[systole|systolic function]] is affected by associated conditions such as peripheral [[pulmonary artery stenosis]] and [[pulmonary hypertension]] which further increase the severity of [[pulmonary regurgitation]]. Among [[patients]] with severe [[PR|pulmonary regurgitation]] (PR), the gene expression pattern of GRK2 and β2-[[Adrenergic receptor|adrenoceptor]] ( molecular markers of [[cardiac dysfunction]]) has been reported to be altered. [[Chromosome abnormality|chromosomal anomalies]] such as [[Trisomy 21]], [[Trisomy 13]], [[chromosome]] 6 and 7 deletions may be associated with conditions such as APVS (Absent Pulmonary Valve Syndrome). Isolated [[PR]] is uncommon and is usually demonstrated with other [[valve|valvular]] abnormalities or in certain conditions. Conditions associated include [[TOF]], [[rheumatic heart disease]] and [[syphilis]]. On gross pathology vegetative lesions on the [[pulmonic valve]] leaflets may be observed in a [[patient]] with [[acquired]] alteration in the [[valve|valvular]] leaflet [[morphology]].
[[Pulmonary valve]] is located at the junction of the [[Ventricular outflow tract|right ventricular outflow tract]] and [[pulmonary artery]]. Three equal-sized, semilunar cusps or leaflets make up the [[pulmonary valve]]. [[Pulmonary valve]] opens during right ventricular [[systole]] and closes during right ventricular [[diastole]]. [[PR|Pulmonary regurgitation]] (PR) may be caused by an acquired alteration in the valvular morphology, idiopathic dilatation of the pulmonary artery (IDPA), congenital absence or malformation of the pulmonary valve|valve]], and increasing regurgitation causing [[right ventricle|right ventricular]] volume overload. The pathophysiologic mechanism of [[pulmonic regurgitation]] includes [[right ventricular overload]] resulting in the right [[ventricular remodeling]] and progressive decline in function. The rate of decline in right ventricular [[systole|systolic function]] is affected by associated conditions such as peripheral [[pulmonary artery stenosis]] and [[pulmonary hypertension]] which further increase the severity of [[pulmonary regurgitation]]. Among [[patients]] with severe [[PR|pulmonary regurgitation]] (PR), the gene expression pattern of GRK2 and β2-[[Adrenergic receptor|adrenoceptor]] ( molecular markers of [[cardiac dysfunction]]) has been reported to be altered. Isolated [[PR]] is uncommon and is usually demonstrated with other [[valve|valvular]] abnormalities or in certain conditions. Conditions associated include [[TOF]], [[rheumatic heart disease]] and [[syphilis]]. On gross pathology vegetative lesions on the [[pulmonic valve]] leaflets may be observed in a [[patient]] with [[acquired]] alteration in the [[valve|valvular]] leaflet [[morphology]].


==Pathophysiology==
==Pathophysiology==

Revision as of 22:43, 4 August 2020

Pulmonic regurgitation Microchapters

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Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differential diagnosis

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Electrocardiogram

Chest X-Ray

Echocardiography

Cardiac MRI

Severity Assessment

Treatment

Medical Therapy

Surgical therapy

Follow up

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2], Aysha Anwar, M.B.B.S[3], Javaria Anwer M.D.[4]

Overview

Pulmonary valve is located at the junction of the right ventricular outflow tract and pulmonary artery. Three equal-sized, semilunar cusps or leaflets make up the pulmonary valve. Pulmonary valve opens during right ventricular systole and closes during right ventricular diastole. Pulmonary regurgitation (PR) may be caused by an acquired alteration in the valvular morphology, idiopathic dilatation of the pulmonary artery (IDPA), congenital absence or malformation of the pulmonary valve|valve]], and increasing regurgitation causing right ventricular volume overload. The pathophysiologic mechanism of pulmonic regurgitation includes right ventricular overload resulting in the right ventricular remodeling and progressive decline in function. 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. Among patients with severe pulmonary regurgitation (PR), the gene expression pattern of GRK2 and β2-adrenoceptor ( molecular markers of cardiac dysfunction) has been reported to be altered. Isolated PR is uncommon and is usually demonstrated with other valvular abnormalities or in certain conditions. Conditions associated include TOF, rheumatic heart disease and syphilis. On gross pathology vegetative lesions on the pulmonic valve leaflets may be observed in a patient with acquired alteration in the valvular leaflet morphology.

Pathophysiology

Anatomy of and physiology of pulmonic valve

Cadaveric specimen of heart demonstrating pulmonary valve location between right ventricular outflow tract and pulmonary artery - By Anatomist90 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20481209
  • Structure: Three equal sized, semilunar cusps or leaflets make up the pulmonary valve. Based on the corresponding aortic valve, the cusps are named right, left and anterior.[2] [2]
  • The three cusps are joined by commissures and the cusps are thinner when compared to the aortic valve, due to a low pressure in the right ventricle.[2]
  • Histologically, the pulmonary valve consists of stratified extracellular matrix compartments. The layers constitute fibrosa, spongiosa and ventricularis.[3]
  • The diameter of pulmonic valve is demonstrated to be closely related to the body size. For adult men (>17 yeras age) mean pulmonary valve diameter is 26.2 +/- 2.3 mm and 23.9 +/- 2.2 mm for adult women.[4]
  • Physiology: The right ventricle delivers the received blood entirely to the pulmonary circulation every beat, maintaining optimum pressure.[5] Pulmonary valve opens during right ventricular systole allowing the deoxygenated blood to be delivered to the lungs. [2] During the right ventricular diastole the pulmonary valves close completely to prevent regurgitation (back flow) of the blood into the right ventricle.[2]
  • The closure of the pulmonic valve contributes to the P2 component of the second heart sound (S2).

Pathogenesis

The pathogenesis of pulmonic regurgitation involves the following mechanisms:[6][7]

Dynamics of regurgitation

PR volume = regurgitant orifice area · constant · diastolic time · mean diastolic pressure difference between the MPA and RV.(P2−P1)0.5.

Acquired alteration in the valvular morphology[11][10]

Regurgitation is avoided despite large regurgitation orifice due to Torricelli principle. Progressively, an increased size and capacitance of central pulmonary ateries and right ventricular dilatation occurs due to increased RV stroke volume. The changes described progress with age accompanied by a longer duration of diastole and decreased heart rate. This progressively leads to an increase in the degree of PR.

A few factors influencing the progression of pulmonary regurgitation (PR) after TOF repair - [10]

Idiopathic dilatation of the pulmonary artery (IDPA)[12][13][14]

3-D reconstruction of chest CT demonstrating diffuse aneurysmal dilatation of the pulmonary outflow tract and main pulmonary artery (right and left) - [15]

Congenital absence or malformation of the valve[16][12][13][17]

Quadricuspid pulmonary valve (one of the congenital causes of PR - Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology http://www.peir.net

Increasing regurgitation causing right ventricular volume overload[9]

Genetics

Associated conditions

Isolated PR is uncommon and is usually demonstrated with other valvular abnormalities or in certain conditions. The most important conditions/diseases associated with PR include:

Gross pathology

Microscopic pathology


References

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  16. Bouzas, Beatriz; Kilner, Philip J.; Gatzoulis, Michael A. (2005). "Pulmonary regurgitation: not a benign lesion". European Heart Journal. 26 (5): 433–439. doi:10.1093/eurheartj/ehi091. ISSN 0195-668X.
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See Also

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