Difference between revisions of "Tetralogy of Fallot"

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{{review}}
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== Introduction ==
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{{dog}}{{cat}}
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===Signalment===
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Genetics & Predisposed Breeds: Keeshonds, Miniature Poodles, Miniature Schnauzers, English Bulldogs, Wire-haired Fox Terriers
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===Description===
  
 
The Four Defects Below Are Present in Tetrology of Fallot:
 
The Four Defects Below Are Present in Tetrology of Fallot:
  
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*[[Pulmonic Stenosis]] (Increases right ventricular pressure)  
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*Pulmonic Stenosis (Increases right ventricular pressure)  
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*[[Ventricular Septal Defect]] (Leads to shunting of blood from right to left)  
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*Ventricular Septal Defect (Leads to shunting of blood from right to left)  
 +
 
 
*Overriding Aorta (Obtains blood from both ventricles)  
 
*Overriding Aorta (Obtains blood from both ventricles)  
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*Hypertrophy of the Right Ventricle (Direct result of pulmonic stenosis; Contributes to an increase in ventricular pressure) <br>
 
  
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The outcome of the combined defects listed above depends on their severity. Usually the animal experiences pulmonary underperfusion and unoxygenated blood in the systemic circulation. Unoxygenated blood in the systemic circulation creates the hypoxic conditions necessary to stimulate the kidney’s release of the hormone [[Kidney Endocrine Function - Anatomy & Physiology#Erythropoietin|erythropoietin]]. Erythropoietin travels to the bone marrow and stimulates an increase in red blood cell production. The increase in red blood cells can lead to polycythaemia. Overproduction of red blood cells increases the viscosity of blood leading to poor circulation and decreased oxygen delivery. Intravascular [[Thrombosis|thrombi]], haemorrhage, and stroke are just a few of the complications resulting from polycythaemia.  
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*Hypertrophy of the Right Ventricle (Direct result of pulmonic stenosis; Contributes to an increase in ventricular pressure)
 +
 
 +
 
 +
The outcome of the combined defects listed above depends on their severity. Usually the animal experiences pulmonary underperfusion and unoxygenated blood in the systemic circulation. Unoxygenated blood in the systemic circulation creates the hypoxic conditions necessary to stimulate the kidney’s release of the hormone erythropoietin. Erythropoietin travels to the bone marrow and stimulates an increase in red blood cell production. The increase in red blood cells can lead to polycythaemia. Overproduction of red blood cells increases the viscosity of blood leading to poor circulation and decreased oxygen delivery. Intravascular thrombi, haemorrhage, and stroke are just a few of the complications resulting from polycythaemia.
 +
 
 +
===Diagnosis===
 +
====History & Clinical Signs====
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-Lethargy
 +
 
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-Cyanosis
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-Stunted Growth
 +
 
 +
-Exercise Intolerance
 +
 
 +
-Syncope
 +
 
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-Seizures
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====Physical Exam====
  
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==Signalment==
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-Systolic murmur (over left heart base): due to pulmonic stenosis
  
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Certain breeds are predisposed to the disease and these include Keeshonds, Miniature Poodles, Miniature Schnauzers, English Bulldogs and Wire-haired Fox Terriers.
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-Systolic murmur (over right sternal boarder): due to ventricular septal defect
  
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== Clinical Signs ==
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-Precordial thrill (palpable over both areas)
  
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May vary depending on severity but include lethargy, cyanosis, stunted growth, exercise intolerance, syncope and [[Seizures|seizures]].
 
  
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== Diagnosis ==
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====Radiographic Findings====
  
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History and clinical examination findings, plus physical examination findings. These will often include a systolic [[Heart Murmurs|murmur]] (over left heart base): due to pulmonic stenosis, a systolic murmur (over right sternal border): due to ventricular septal defect and a precordial thrill (palpable over both areas).
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-Right Ventricular Hypertrophy
  
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Radiographs of the thorax will show right ventricular hypertrophy and pulmonary underperfusion.
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-Pulmonary Underperfusion
  
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Echocardiographic findings will include structural abnormalities described and doppler will reveal the presence of a shunt and its abnormal blood flow.
 
  
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Electrocardiographic (ECG) findings will indicate right ventricular enlargement by the presence of deep S-waves.
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====Echocardiographic Findings====
  
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== Treatment ==
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-Structural Abnormalities Can Be Detected
  
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Surgical treatment options include open heart surgery for complete correction (rarely done in animals).
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-Doppler exam reveals the presence of a shunt and its abnormal blood flow
  
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Palliative surgery includes anastamosis of either the ascending aorta or subclavian artery to the pulmonary artery improves pulmonary blood flow.
 
  
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Medical options include exercise restriction, phlebotomy (bleeding): helps to reduce blood viscosity and improve oxygen delivery to the tissues by maintaining PCV below 65% and beta-blockers: reduce shunting and protect the heart from hypertrophy.
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====Electrocardiographic (ECG) Findings====
  
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== Prognosis ==
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-Indication of right ventricular enlargement by the presence of deep S-waves
  
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Guarded, but depends on the severity of defects and the level of polycythemia.
 
  
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Without treatment, animals will live only a couple of years with poor exercise tolerance. With treatment, animals can live up to seven years.
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===Treatment===
  
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{{Learning
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*Surgical
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|flashcards =[[Cardiovascular Developmental Pathology Flashcards]]
 
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|videos = [[Sheep Tetralogy of Fallot video]]
 
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}}
 
  
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== References ==
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-Open Heart Surgery for complete correction (Rarely done in animals)
  
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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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-Palliative Surgery: Anastamosis of either the ascending aorta or subclavian artery to the pulmonary artery improves pulmonary blood flow.
  
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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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*Medical
  
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Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier
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-Exercise Restriction
  
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-Phlebotomy (Bleeding): helps to reduce blood viscosity and improve oxygen delivery to the tissues by maintaining PCV below 65%
  
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{{review}}
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-Beta-blockers: reduce shunting and protect the heart from hypertrophy
 +
 
 +
===Prognosis===
 +
 
 +
-Guarded, but depends on the severity of defects and the level of polycythemia
 +
 
 +
-Without Treatment: Animals will live only a couple of years with poor exercise tolerance
 +
 
 +
-With Treatment: Animals can live up to seven years
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==From Pathology==
 +
 
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*'''Pulmonic stenosis'''
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*'''Right ventricular hypertrophy'''
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*'''High VSD'''
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*'''Overriding aorta'''
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Commonly reported in certain breeds, E.g Keeshond, Schnauzer, Poodles and terriers.
 +
 
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''Clinical Signs:''
 +
*Cyanotic; see severe exercise intolerance.
 +
*Systolic murmur due to pulmonic stenosis +/- precordial thrill.
 +
*Polycythemia due to chronic hypoxia.
 +
 
 +
''Diagnosis:''
 +
*Right ventricular enlargement on radiology and ECG.
 +
*Post stenotic dilatation of pulmonary artery on radiology and pulmonary undercirculation due to right to left shunting.
 +
*Echocardiography may show right ventricular hypertrophy, paradoxical motion of interventricular septum (pressure RV>LV), visulaisation of VSD and overriding aorta.
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*Doppler useful to image pulmonic stenosis and VSD.
  
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{{OpenPages}}
 
  
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[[Category:Cardiovascular_System_-_Developmental_Pathology]] [[Category:Expert_Review]] [[Category:Cardiac_Diseases_-_Dog]] [[Category:Cardiac_Diseases_-_Cat]] [[Category:Cardiac_Diseases_-_Horse]] [[Category:Cardiac_Diseases_-_Cattle]] [[Category:Cardiac_Diseases_-_Pig]]
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[[Category:Cardiovascular_System_-_Developmental_Pathology]]
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[[Category:Cardiology Section]]
 

Revision as of 12:40, 22 June 2010

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Category:WikiClinical CanineCow
Category:WikiClinical FelineCow

Signalment

Genetics & Predisposed Breeds: Keeshonds, Miniature Poodles, Miniature Schnauzers, English Bulldogs, Wire-haired Fox Terriers

Description

The Four Defects Below Are Present in Tetrology of Fallot:

  • Pulmonic Stenosis (Increases right ventricular pressure)
  • Ventricular Septal Defect (Leads to shunting of blood from right to left)
  • Overriding Aorta (Obtains blood from both ventricles)
  • Hypertrophy of the Right Ventricle (Direct result of pulmonic stenosis; Contributes to an increase in ventricular pressure)


The outcome of the combined defects listed above depends on their severity. Usually the animal experiences pulmonary underperfusion and unoxygenated blood in the systemic circulation. Unoxygenated blood in the systemic circulation creates the hypoxic conditions necessary to stimulate the kidney’s release of the hormone erythropoietin. Erythropoietin travels to the bone marrow and stimulates an increase in red blood cell production. The increase in red blood cells can lead to polycythaemia. Overproduction of red blood cells increases the viscosity of blood leading to poor circulation and decreased oxygen delivery. Intravascular thrombi, haemorrhage, and stroke are just a few of the complications resulting from polycythaemia.

Diagnosis

History & Clinical Signs

-Lethargy

-Cyanosis

-Stunted Growth

-Exercise Intolerance

-Syncope

-Seizures

Physical Exam

-Systolic murmur (over left heart base): due to pulmonic stenosis

-Systolic murmur (over right sternal boarder): due to ventricular septal defect

-Precordial thrill (palpable over both areas)


Radiographic Findings

-Right Ventricular Hypertrophy

-Pulmonary Underperfusion


Echocardiographic Findings

-Structural Abnormalities Can Be Detected

-Doppler exam reveals the presence of a shunt and its abnormal blood flow


Electrocardiographic (ECG) Findings

-Indication of right ventricular enlargement by the presence of deep S-waves


Treatment

  • Surgical

-Open Heart Surgery for complete correction (Rarely done in animals)

-Palliative Surgery: Anastamosis of either the ascending aorta or subclavian artery to the pulmonary artery improves pulmonary blood flow.

  • Medical

-Exercise Restriction

-Phlebotomy (Bleeding): helps to reduce blood viscosity and improve oxygen delivery to the tissues by maintaining PCV below 65%

-Beta-blockers: reduce shunting and protect the heart from hypertrophy

Prognosis

-Guarded, but depends on the severity of defects and the level of polycythemia

-Without Treatment: Animals will live only a couple of years with poor exercise tolerance

-With Treatment: Animals can live up to seven years

From Pathology

  • Pulmonic stenosis
  • Right ventricular hypertrophy
  • High VSD
  • Overriding aorta

Commonly reported in certain breeds, E.g Keeshond, Schnauzer, Poodles and terriers.

Clinical Signs:

  • Cyanotic; see severe exercise intolerance.
  • Systolic murmur due to pulmonic stenosis +/- precordial thrill.
  • Polycythemia due to chronic hypoxia.

Diagnosis:

  • Right ventricular enlargement on radiology and ECG.
  • Post stenotic dilatation of pulmonary artery on radiology and pulmonary undercirculation due to right to left shunting.
  • Echocardiography may show right ventricular hypertrophy, paradoxical motion of interventricular septum (pressure RV>LV), visulaisation of VSD and overriding aorta.
  • Doppler useful to image pulmonic stenosis and VSD.
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