Difference between revisions of "Pulmonic Stenosis"

Latest revision as of 16:59, 9 June 2016

Introduction

Pulmonic stenosis (PS) is one of the three most common congenital cardiac defects in dogs. It is much less common in cats, and is usually recognised in association with other congenital cardiac defects in this species.

Pulmonic stenosis may be subvalvular/infundibular (occurs below the valve), valvular (occurs at the valve) or Supravalvular (occurs above the valve). Most cases of PS in the dog are valvular, whilst supravalvular PS is rare.

Subvalvular (infundibular) PS is defined as a fibrous or fibromuscular diaphragm below the pulmonic valve or at the os infundibulum, or a more diffuse and extensive area of fibromuscular hypertrophy creating more of a tunnel or hour-glass deformity of the infundibulum.

Valvular PS can be further classified into type A or type B, based on valvular morphology. Type A cases have a normal pulmonary annulus diameter and type B cases have a narrow pulmonary annulus diameter, often accompanied by hypoplasia of the pulmonary trunk. Type A cases are more likely to show a post-stenotic dilatation.

Concentric hypertrophy of the right ventricle develops as a consequence of the chronic pressure overload resulting from obstruction to right ventricular outflow. Right ventricular hypertrophy may cause an infundibular narrowing of the right ventricular outflow tract (RVOT), exacerbating the stenosis and resulting in a dynamic component to the obstruction. A further consequence of right ventricular hypertrophy is reduced right ventricular diastolic filling and therefore elevated right atrial pressures with resultant right atrial dilation.

In Bulldogs, PS may be complicated by coronary artery anomalies.

Signalment

Predisposed breeds of dog include the Miniature Schnauzer, Cocker Spaniel, Fox Terrier, Chihuahua, Miniature Pinscher, Labrador Retriever, Newfoundland, Mastiff, Boxer, Samoyed and English and French Bulldog.

History and Clinical Signs

A murmur is usually detected at the initial health check or primary vaccination.

Clinical signs include exercise intolerance, syncope and signs of right sided congestive heart failure (if severely affected). Animals may be asymptomatic.

Diagnosis

Physical Examination

Left-sided, systolic murmur with point of maximal intensity over the heart base
Grade of murmur correlates with severity of stenosis for fixed obstructions
Apex beat may be more palpable on the right hemithorax than the left if severe right ventricular hypertrophy is present.

There may be signs of right sided congestive heart failure, such as ascites and jugular venous distension and hepatojugular reflux.

Thoracic Radiographs

Radiographic findings may include right ventricular enlargement (seen at 1 o'clock on a dorsoventral view), right atrial enlargement and pulmonary artery enlargement (seen at 2 o'clock on a dorsoventral view).

Echocardiographic findings may include right ventricular hypertrophy, poststenotic dilation of the pulmonary artery and abnormal pulmonic valve if the stenotic area is valvular. Doppler can be used to measure the pressure in the stenotic area and visualize abnormal flow.

Electrocardiographic (ECG) signs include right ventricular hypertrophy (tall P waves, deep S waves, deep Q waves, right axis deviation).

Angiography may also be used to identify the defect.

Treatment

The pressure gradient between the right ventricle and the pulmonary artery can be used to decide between medical and surgical management.

In mild to moderate cases, if there are no clinical signs then no treatment is needed.

In severe cases, if the pressure gradient is greater than 100mmHg, an invasive procedure may need to be performed. Possible options for surgery include a balloon valvuloplasty (done if pulmonic leaflets are fused) or surgical repair (done when more complex lesions and obstructions are present): valvulotomy, pericardial patch graft.

If signs of right-sided heart failure are present, these should be managed medically with diuretics and vasodilators.

Prognosis

Mild to moderate cases have a good prognosis. Severe cases have a guarded prognosis.

Pulmonic Stenosis Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Soft Tissue Surgery Q&A 21

References

Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company

Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2) W.B. Saunders Company

Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier

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-{{review}}
+{{OpenPagesTop}}
+== Introduction ==
-{{dog}}{{cat}}{{horse}}
+Pulmonic stenosis (PS) is one of the three most common congenital cardiac defects in dogs. It is much less common in cats, and is usually recognised in association with other congenital cardiac defects in this species.
-*Common in dogs
-*Rare in cats
+Pulmonic stenosis may be '''subvalvular/infundibular'''  (occurs below the valve), '''valvular''' (occurs at the valve) or '''Supravalvular''' (occurs above the valve). '''Most '''cases of PS in the dog are '''valvular''', whilst supravalvular PS is rare.
-*Very rare in horses as an isolated abnormality; usually part of Tetralogy of Fallot
+'''Subvalvular (infundibular)''' PS is defined as a fibrous or fibromuscular diaphragm below the pulmonic valve or at the os infundibulum, or a more diffuse and extensive area of fibromuscular hypertrophy creating more of a tunnel or hour-glass deformity of the infundibulum.
-===Signalment===
+'''Valvular''' PS can be further classified into type A or type B, based on valvular morphology. '''Type A''' cases have a '''normal pulmonary annulus diameter''' and '''type B''' cases have a '''narrow pulmonary annulus diameter''', often accompanied by hypoplasia of the pulmonary trunk. Type A cases are more likely to show a post-stenotic dilatation.
-Genetics & Predisposed Breeds: Most common in smaller breeds (Miniature Schnauzer, Fox Terrier, Chihuahua, Miniature Pinscher); Larger breeds are also affected (Labrador Retriever, Newfoundland, Mastiff, Samoyeds); Terrier Breeds are frequently affected
+Concentric hypertrophy of the right ventricle develops as a consequence of the chronic pressure overload resulting from obstruction to right ventricular outflow. Right ventricular hypertrophy may cause an infundibular narrowing of the right ventricular outflow tract (RVOT), exacerbating the stenosis and resulting in a dynamic component to the obstruction. A further consequence of right ventricular hypertrophy is reduced right ventricular diastolic filling and therefore elevated right atrial pressures with resultant right atrial dilation.
-===Description===
+In '''Bulldogs''', PS may be complicated by '''coronary artery anomalies'''.
-The three possible areas for pulmonic stenosis to occur:
+==Signalment==
-. Subvalvular or subpulmonic (occurs below the valve)
+Predisposed breeds of dog include the Miniature Schnauzer, Cocker Spaniel, Fox Terrier, Chihuahua, Miniature Pinscher, Labrador Retriever, Newfoundland, Mastiff, Boxer, Samoyed and English and French Bulldog.
-. Valvular (occurs at the valve)
+== History and Clinical Signs ==
+A murmur is usually detected at the initial health check or primary vaccination.
-. Supravalvular (occurs above the valve)
+Clinical signs include exercise intolerance, syncope and signs of [[Heart Failure, Right-Sided|right sided congestive heart failure]] (if severely affected). Animals may be asymptomatic.
+== Diagnosis ==
+===Physical Examination===
+* Left-sided, systolic murmur with point of maximal intensity over the heart base
+* Grade of murmur correlates with severity of stenosis for fixed obstructions
+* Apex beat may be more palpable on the right hemithorax than the left if severe right ventricular hypertrophy is present.
-*Stenosis of the pulmonary outflow tract is the result of dysplastic changes in the pulmonic valve
-*Most cases of pulmonic stenosis are valvular
+There may be signs of [[Heart Failure, Right-Sided|right sided congestive heart failure]], such as ascites and jugular venous distension and hepatojugular reflux.
+===Thoracic Radiographs===
+Radiographic findings may include right ventricular enlargement (seen at 1 o'clock on a dorsoventral view), right atrial enlargement and pulmonary artery enlargement (seen at 2 o'clock on a dorsoventral view).
-*Supravalvular pulmonic stenosis is rare
+'''Echocardiographic''' findings may include right ventricular hypertrophy, poststenotic dilation of the pulmonary artery and abnormal pulmonic valve if the stenotic area is valvular. Doppler can be used to measure the pressure in the stenotic area and visualize abnormal flow.
-*Concentric hypertrophy of the right ventricle forms as a direct result of the chronic pressure overload needed to surpass the increased resistance from the stenotic pulmonary outflow tract
+'''Electrocardiographic '''(ECG) signs include right ventricular hypertrophy (tall P waves, deep S waves, deep Q waves, right axis deviation).
-*Concentric hypertrophy causes decreased ventricular filling during diastole
+Angiography may also be used to identify the defect.
-*Elevated right atrial pressure from the blood unable to fill the ventricle causes atrial dilation
+== Treatment ==
-*Tricuspid valve regurgitation can also be present and adds to the atrial pressure
+The '''pressure gradient''' between the right ventricle and the pulmonary artery can be used to decide between medical and surgical management.
-*In addition to the diagnostic methods listed below, angiography may be used to show the defect
+In mild to moderate cases, if there are no clinical signs then '''no treatment is needed'''.
+In severe cases, if the pressure gradient is greater than 100mmHg, an invasive procedure may need to be performed. Possible options for surgery include a '''balloon valvuloplasty''' (done if pulmonic leaflets are fused) or '''surgical repair''' (done when more complex lesions and obstructions are present): '''valvulotomy, pericardial patch graft'''.
-===Diagnosis===
+If signs of right-sided heart failure are present, these should be managed medically with diuretics and vasodilators.
-====History & Clinical Signs====
+== Prognosis ==
--Exercise Intolerance
+Mild to moderate cases have a good prognosis. Severe cases have a guarded prognosis.
--Syncope
+{{Learning
+|flashcards = [[Small Animal Soft Tissue Surgery Q&A 21]]
+}}
--Signs of right sided congestive heart failure (severely affected)
+== References ==
--Asymptomatic (mildly affected)
+Ettinger, S.J. and Feldman, E. C. (2000) '''Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat''' Volume 2 (Fifth Edition) ''W.B. Saunders Company''
-====Physical Exam====
+Ettinger, S.J, Feldman, E.C. (2005) '''Textbook of Veterinary Internal Medicine''' (6th edition, volume 2) ''W.B. Saunders Company''
--Systolic ejection murmur over pulmonary artery in the left heart base
+Fossum, T. W. et. al. (2007) '''Small Animal Surgery '''(Third Edition)'' Mosby Elsevier ''
--Usually normal femoral pulses
--Signs of right sided congestive heart failure may be present:
+{{review}}
-*ascites
-*jugular distension & jugular pulses
-====Radiographic Findings====
--Right ventricular enlargement (DV view seen at 1 o'clock)
--Right atrial enlargement
--Pulmonary artery enlargement (DV view seen at 2 o'clock)
-(Changes are seen the most clearly on a dorsoventral view)
-====Echocardiographic Findings====
--Right ventricular hypertrophy
--Poststenotic dilation of the pulmonary artery
--Abnormal pulmonic valve if the stenotic area is valvular
-Doppler can be used to measure the pressure in the stenotic area and visualize abnormal flow
-====Electrocardiographic (ECG)====
--Right ventricular hypertrophy (deep S waves, right axis deviation)
-===Treatment===
-Mild/Moderate Cases
--If there are no signs, no treatment is needed
-Severe Cases
--Animals that exhibit many of the clinical signs will need further treatment
-*Balloon valvuloplasty (done if pulmonic leaflets are fused)
-*Surgical repair (done when more complex lesions & obstructions are present): valvulotomy, pericardial patch graft
-===Prognosis===
-Mild/Moderate Cases
--Good prognosis
-Severe Cases
--Guarded prognosis
-==From Pathology==
-Obstructs blood flowing form the right ventricle to the pulmonary artery.  As with aortic stenosis may be subvalvular, valvular or supravalvular.  Valvular stenosis is the most common form in the dog.
-''Incidence:''
-*Increased incidence in English bulldogs, Cocker spaniels, Chihuahuas.
-*Autosomal dominant in Beagles.
-''Clinical Signs:''
-*Asymptomatic if mild or moderate.
-*If severe; exercise intolerance, stunting, syncope, right sided heart failure E.g. ascites.
-*Harsh systolic murmur at left heart base.
-*May hear splitting of the second heart sound due to delayed closure of the pulmonic valve.
-*Femoral pulse quality good but jugulars distended.
-''Diagnosis:''
-*Right ventricular enlargement on radiology, along with post-stenotic dilatation of the pulmonary artery and pulmonary undercirculation.
-*Abnormal valve can be imaged using echocardiography.
-*Severity of stenosis can be assessed using Doppler to calculate flow rates.
-''Treatment:''
+{{OpenPages}}
-*Balloon valvuloplasty is treatment of choice.
-[[Category:Cardiovascular_System_-_Developmental_Pathology]]
+[[Category:Cardiovascular_System_-_Developmental_Pathology]] [[Category:Expert_Review]] [[Category:Cardiac_Diseases_-_Cat]] [[Category:Cardiac_Diseases_-_Dog]] [[Category:Cardiac_Diseases_-_Horse]]
-[[Category:To_Do_-_Cardiovascular]]
+[[Category:Cardiology Section]]