Difference between revisions of "Tetralogy of Fallot"
Jump to navigation
Jump to search
| (7 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
| − | + | ===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: | 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) | *Overriding Aorta (Obtains blood from both ventricles) | ||
| − | |||
| − | 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 | + | *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. | ||
| + | ==Test yourself with the Developmental Pathology Flashcards== | ||
| − | + | [[Developmental_Pathology_Flashcards_-_Pathology|Developmental Pathology Flashcards]] | |
| − | |||
| − | [[Category:Cardiovascular_System_-_Developmental_Pathology]] [[Category: | + | [[Category:Cardiovascular_System_-_Developmental_Pathology]] |
| − | [[Category: | + | [[Category:To_Do_-_Cardiovascular]][[Category:Cardiac Diseases - Dog]][[Category:Cardiac Diseases - Cat]] |
| + | [[Category:Cardiac Diseases - Horse]] | ||
| + | [[Category:Cardiac Diseases - Cattle]] | ||
| + | [[Category:Cardiac Diseases - Pig]] | ||
Revision as of 19:26, 17 January 2011
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.