Difference between revisions of "Pulmonic Stenosis"

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== Introduction ==
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{{dog}}{{cat}}{{horse}}
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*Common in dogs
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*Rare in cats
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*Very rare in horses as an isolated abnormality; usually part of Tetralogy of Fallot
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===Signalment===
 +
 
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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
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===Description===
 +
 
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The three possible areas for pulmonic stenosis to occur:
 +
 
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1. Subvalvular or subpulmonic (occurs below the valve)
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2. Valvular (occurs at the valve)
  
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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.
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3. Supravalvular (occurs above the valve)
  
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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. 
 
  
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'''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.
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*Stenosis of the pulmonary outflow tract is the result of dysplastic changes in the pulmonic valve  
  
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'''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.
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*Most cases of pulmonic stenosis are valvular
  
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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.
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*Supravalvular pulmonic stenosis is rare
  
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In '''Bulldogs''', PS may be complicated by '''coronary artery anomalies'''.
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*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
  
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==Signalment==
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*Concentric hypertrophy causes decreased ventricular filling during diastole
  
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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.
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*Elevated right atrial pressure from the blood unable to fill the ventricle causes atrial dilation
  
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== History and Clinical Signs ==
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*Tricuspid valve regurgitation can also be present and adds to the atrial pressure
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A murmur is usually detected at the initial health check or primary vaccination.
 
  
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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.
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*In addition to the diagnostic methods listed below, angiography may be used to show the defect
  
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== Diagnosis ==
 
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===Physical Examination===
 
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* Left-sided, systolic murmur with point of maximal intensity over the heart base
 
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* Grade of murmur correlates with severity of stenosis for fixed obstructions
 
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* Apex beat may be more palpable on the right hemithorax than the left if severe right ventricular hypertrophy is present.
 
  
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===Diagnosis===
  
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There may be signs of [[Heart Failure, Right-Sided|right sided congestive heart failure]], such as ascites and jugular venous distension and hepatojugular reflux.
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====History & Clinical Signs====
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===Thoracic Radiographs===
 
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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).
 
  
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'''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.
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-Exercise Intolerance
  
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'''Electrocardiographic '''(ECG) signs include right ventricular hypertrophy (tall P waves, deep S waves, deep Q waves, right axis deviation).
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-Syncope
  
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Angiography may also be used to identify the defect.
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-Signs of right sided congestive heart failure (severely affected)
  
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== Treatment ==
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-Asymptomatic (mildly affected)
  
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The '''pressure gradient''' between the right ventricle and the pulmonary artery can be used to decide between medical and surgical management.
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====Physical Exam====
  
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In mild to moderate cases, if there are no clinical signs then '''no treatment is needed'''.
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-Systolic ejection murmur over pulmonary artery in the left heart base
  
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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'''.
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-Usually normal femoral pulses
  
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If signs of right-sided heart failure are present, these should be managed medically with diuretics and vasodilators.
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-Signs of right sided congestive heart failure may be present:
  
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== Prognosis ==
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*ascites
  
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Mild to moderate cases have a good prognosis. Severe cases have a guarded prognosis.
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*jugular distension & jugular pulses
  
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{{Learning
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====Radiographic Findings====
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|flashcards = [[Small Animal Soft Tissue Surgery Q&A 21]]
 
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}}
 
  
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== References ==
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-Right ventricular enlargement (DV view seen at 1 o'clock)
  
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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''
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-Right atrial enlargement
  
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Ettinger, S.J, Feldman, E.C. (2005) '''Textbook of Veterinary Internal Medicine''' (6th edition, volume 2) ''W.B. Saunders Company''
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-Pulmonary artery enlargement (DV view seen at 2 o'clock)
  
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Fossum, T. W. et. al. (2007) '''Small Animal Surgery '''(Third Edition)'' Mosby Elsevier ''
 
  
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(Changes are seen the most clearly on a dorsoventral view)
  
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{{review}}
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====Echocardiographic Findings====
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 +
-Right ventricular hypertrophy
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 +
-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==
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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:''
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*Increased incidence in English bulldogs, Cocker spaniels, Chihuahuas.
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*Autosomal dominant in Beagles.
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''Clinical Signs:''
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*Asymptomatic if mild or moderate.
 +
*If severe; exercise intolerance, stunting, syncope, right sided heart failure E.g. ascites.
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*Harsh systolic murmur at left heart base.
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*May hear splitting of the second heart sound due to delayed closure of the pulmonic valve.
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*Femoral pulse quality good but jugulars distended.
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 +
''Diagnosis:''
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*Right ventricular enlargement on radiology, along with post-stenotic dilatation of the pulmonary artery and pulmonary undercirculation.
 +
*Abnormal valve can be imaged using echocardiography.
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*Severity of stenosis can be assessed using Doppler to calculate flow rates.
  
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{{OpenPages}}
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''Treatment:''
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*Balloon valvuloplasty is treatment of choice.
  
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[[Category:Cardiovascular_System_-_Developmental_Pathology]] [[Category:Expert_Review]] [[Category:Cardiac_Diseases_-_Cat]] [[Category:Cardiac_Diseases_-_Dog]] [[Category:Cardiac_Diseases_-_Horse]]
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[[Category:Cardiovascular_System_-_Developmental_Pathology]]
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[[Category:Cardiology Section]]
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[[Category:To_Do_-_Cardiovascular]]

Revision as of 12:50, 1 July 2010

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  • Common in dogs
  • Rare in cats
  • Very rare in horses as an isolated abnormality; usually part of Tetralogy of Fallot

Signalment

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

Description

The three possible areas for pulmonic stenosis to occur:

1. Subvalvular or subpulmonic (occurs below the valve)

2. Valvular (occurs at the valve)

3. Supravalvular (occurs above the valve)


  • Stenosis of the pulmonary outflow tract is the result of dysplastic changes in the pulmonic valve
  • Most cases of pulmonic stenosis are valvular
  • Supravalvular pulmonic stenosis is rare
  • 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
  • Concentric hypertrophy causes decreased ventricular filling during diastole
  • Elevated right atrial pressure from the blood unable to fill the ventricle causes atrial dilation
  • Tricuspid valve regurgitation can also be present and adds to the atrial pressure
  • In addition to the diagnostic methods listed below, angiography may be used to show the defect


Diagnosis

History & Clinical Signs

-Exercise Intolerance

-Syncope

-Signs of right sided congestive heart failure (severely affected)

-Asymptomatic (mildly affected)

Physical Exam

-Systolic ejection murmur over pulmonary artery in the left heart base

-Usually normal femoral pulses

-Signs of right sided congestive heart failure may be present:

  • 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:

  • Balloon valvuloplasty is treatment of choice.
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