Difference between revisions of "Ventricular Septal Defect"

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== Introduction ==
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[[Image:VSD1.jpg|thumb|right|150px|<small><center><b>Ventricular septal defect</b>. Courtesy of A. Jefferies</center></small>]]  
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|linkpage =Cardiology - WikiClinical
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[[Image:VSD2.jpg|thumb|right|150px|<small><center><b>Ventricular septal defect</b>. Courtesy of A. Jefferies</center></small>]]  
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|linktext =Cardiology
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|sublink1=Cardiovascular Conditions - WikiClinical
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|subtext1=CARDIOVASCULAR CONDITIONS
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|maplink1= Cardiovascular Conditions (Content Map) - WikiClinical
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|pagetype=Clinical
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<br>
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[[Image:VSD1.jpg|right|thumb|125px|<small><center>'''Ventricular septal defect'''. Courtesy of A. Jefferies</center></small>]]
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[[Image:VSD2.jpg|right|thumb|125px|<small><center>'''Ventricular septal defect'''. Courtesy of A. Jefferies</center></small>]]
 +
 
 +
*Most common congenital cardiac abnormality in large animals
 +
 
 +
*Second most common congenital cardiac abnormality in cat
 +
 
 +
*Occurs in dogs
 +
 
 +
===Signalment===
 +
 
 +
Genetics & Predisposed Breeds: Keeshonds, English Springer Spaniel, English Bulldog, West Highland White Terrier
 +
 
 +
 
 +
===Description===
 +
 
 +
*Ventricular defects are usually in the membranous area of the interventricular septum.
 +
 
 +
*On the right ventricle, the septal defect usually occurs below the septal leaflet of the tricuspid valve.
 +
 
 +
*On the left ventricle, the septal defect usually occurs under the aortic valve.
 +
 
 +
*Ventricular Septal Defects can occur alone or in combination with other congenital malformations.
 +
 
 +
*Usually blood flows from the higher pressure left ventricle through the shunt to the lower pressure right ventricle. Left to right shunting causes volume overload of the pulmonary circulation and consequently the left atrium and ventricle. The consequences of L-R shunting are left sided congestive heart failure and pulmonary hypertension.
 +
 
 +
*Shunting can be reversed from L-R towards R-L if pulmonary hypertension increases the pressure on the right side of the heart and/or there is also pulmonic stenosis (Eisenmengers's Physiology). A R-L shunt would allow unoxygenated blood into the systemic circulation resulting in arterial hypoxemia. Increased amounts of blood into the systemic circulation causes an increased right sided pressure load.
  
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Ventricular septal defects (VSDs) are the most common congenital cardiac abnormality in large animals and the second most common congenital cardiac abnormality in cats (12-56% of congenital heart disease cases). They less commonly occur in dogs (6-12% of congenital heart disease cases).
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===Diagnosis===
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====History & Clinical Signs====
  
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The lesion is usually in the '''membranous area''' of the interventricular septum, just below the aortic valve and the septal tricuspid leaflet.
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-Coughing
  
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Ventricular Septal Defects can occur alone or in combination with other congenital malformations, such as [[Tetralogy of Fallot]]. Usually blood flows from the higher pressure left ventricle through the VSD to the lower pressure right ventricle during systole. Significant left-to-right shunting causes volume overload of the pulmonary circulation, increasing pulmonary venous return to the left atrium and consequently the left ventricle. This may result in volume overload of the left heart with consequent [[Heart Failure, Left-Sided|left-sided congestive heart failure]] and [[Pulmonary Hypertension|pulmonary hypertension]]. If chronic over-circulation of the pulmonary vasculature occurs, pulmonary hypertension may develop. Pulmonary hypertension causes increased right ventricular pressures and therefore right-to-left shunting during systole may occur; this is known as '''Eisenmenger's syndrome'''. Right-to-left shunting allows deoxygenated blood to enter the systemic circulation, resulting in arterial hypoxaemia and cyanosis.
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-Exercise Intolerance
  
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Small VSDs provide high resistance to flow, as high pressure gradients between the left and right ventricle are maintained. These are known as '''restrictive''' or '''resistive''' VSDs, and are usually of no haemodynamic consequence. Larger VSDs offer little resistance to the shunting of blood and are more likely to result in haemodynamic consequences. Very large, unrestrictive defects cause the pressures in both ventricles to equilibrate and the two ventricles behave as a common pumping chamber. Unless the pulmonary circulation is protected by a stenotic pulmonic valve, the development of pulmonary hypertension is unavoidable.
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-Left-sided congestive heart failure
  
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-Right-sided heart failure
  
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==Signalment==
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-Cyanosis (with R-L shunt)
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Predisposed breeds include the Lakeland Terrier, Cocker Spaniel, French Bulldog and West Highland White Terrier.
 
  
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== History and Clinical Signs ==
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-Asymptomatic (small defects)
  
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A murmur is usually detected at the first health check, or primary vaccination. Most affected animals are asymptomatic, but large defects can result in [[Heart Failure, Left-Sided|left-sided congestive heart failure]]. Right-to-left shunting can cause stunted growth and exercise intolerance.
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====Physical Exam====
  
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== Diagnosis ==
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-Holosystolic murmur over left apex and right sternal boarder
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===Physical Examination===
 
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* '''Systolic''' murmur with point of maximum intensity on the '''right''', cranial hemithorax (blood shunts to the right) The murmur can also be detected on the left side, either due to radiation of the primary murmur or the relative pulmonic stenosis caused by the increased blood flow across the pulmonic valve. There may also be a diastolic component to the murmur if aortic regurgitation is present, as a result of the aortic valve prolapsing into the VSD.
 
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* Murmur grade is inversely proportional to the size of the defect, as smaller defects provide more resistance and therefore produce louder murmurs
 
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* Cyanosis may be present with right-to-left shunts
 
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===Thoracic Radiographs===
 
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* Left ventricular enlargement
 
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* Left atrial enlargement
 
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* Right ventricular enlargement
 
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* Pulmonary over-circulation may be present if the left-to-right shunting is significant
 
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===Echocardiography===
 
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* Left atrial dilation
 
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* Left ventricular dilation (eccentric hypertrophy)
 
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* Hyperkinetic left ventricle
 
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* May be able to visualise large defects
 
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* Spectral or colour flow Doppler can be used to interrogate the right ventricular side of the VSD and should demonstrate left-to-right flow
 
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* Velocity of blood flow accross the VSD can be measured, using Doppler, to assess the pressure gradient. High velocity flow is associated with small defects.
 
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* Mitral regurgitation is common
 
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* Aortic regurgitation can occur if the aortic valve prolapses into the VSD
 
  
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== Management ==
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-Systolic murmur over pulmonic valve (pulmonic stenosis)
  
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Treatment may be unnecessary, as the defect may close on its own. Treatment is also not necessary for small VSDs that are of no haemodynamic significance.
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-Diastolic murmur over aortic valve (aortic regurgitation)
  
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In severe cases, [[Heart Failure, Left-Sided|congestive heart failure]] should be appropriately managed. The principle palliative surgical procedure described is pulmonary artery anding, in order to protect the pulmonary vascular bed and therefore prevent the development of pulmonary hypertension. Transcatheter closure of VSDs using an Amplatzer device has also been described in a dog.
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-Murmur from mitral regurgitation (caused by left ventricular dilation)
  
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If significant right to left shunting  with resultant '''polycythaemia''' is present, occlusion of the VSD is contraindicated.
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====Radiographic Findings====
  
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== Prognosis ==
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Normal findings with small defects
  
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In mild to moderate cases the prognosis is excellent. In severe cases, the prognosis is guarded to poor.
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'''Left to Right Ventricular Septal Defect'''
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{{Learning
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|flashcards = [[Cardiovascular Developmental Pathology Flashcards]]
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-Pulmonary overcirculation
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}}
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-Left-sided heart enlargement
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-Signs of left-sided heart failure
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-Enlargement of pulmonary artery (if pulmonic stenosis is present)
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-Right ventricular enlargement (seen with pulmonary hypertension)
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'''Right to Left Ventricular Septal Defect'''
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-Right-sided heart enlargement
 +
 
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-Normal to enlarged pulmonary artery
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====Echocardiographic Findings====
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-Visible defect in the intraventricular septum
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Doppler confirms blood shunting through defect
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====Electrocardiographic (ECG)====
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-Left sided enlargement (L-R shunt)
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-Right ventricular hypertrophy (R-L shunt)
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-Arrhythmias
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-Wide or notched Q wave showing abnormal septal depolarization
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===Treatment===
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'''Mild/Moderate Cases'''
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-No treatment
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-May close on their own
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'''Severe Cases'''
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Medications:
 +
 
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-Drugs to decrease volume through the shunt (arterial vasodilators for R-L shunt)
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 +
-Drugs to combat heart failure
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 +
Surgery:
 +
 
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-Surgical closure of the septal defect (open heart surgery rarely performed in veterinary patients)
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-Pulmonary artery banding (Palliative surgical procedure to decrease left to right shunting)
  
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== References ==
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*Use of vasodilators and the surgical procedures above are contraindicated with a right to left shunt
  
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Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.
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===Prognosis===
  
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Saunders, A.B et. al. Hybrid technique for ventricular septal defect closure in a dog using an Amplatzer Duct Occluder II, JVC (2013) 15, 217-224
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'''Mild/Moderate Cases'''
  
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Bomassi, E. et.al. Signalment, clinical features, echocardiographic findings and outcome of dogs and cats with ventricular septal defects: 109 cases (1992-2013), J Am Vet Med Assoc (2015), July 15; 247(2):166-75
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-Excellent
  
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{{review}}
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'''Severe Cases'''
  
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{{OpenPages}}
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-Guarded (L-R shunts)
  
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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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-Poor (R-L shunts)
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[[Category:Cardiology Section]]
 

Revision as of 13:30, 5 September 2008

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Ventricular septal defect. Courtesy of A. Jefferies
Ventricular septal defect. Courtesy of A. Jefferies
  • Most common congenital cardiac abnormality in large animals
  • Second most common congenital cardiac abnormality in cat
  • Occurs in dogs

Signalment

Genetics & Predisposed Breeds: Keeshonds, English Springer Spaniel, English Bulldog, West Highland White Terrier


Description

  • Ventricular defects are usually in the membranous area of the interventricular septum.
  • On the right ventricle, the septal defect usually occurs below the septal leaflet of the tricuspid valve.
  • On the left ventricle, the septal defect usually occurs under the aortic valve.
  • Ventricular Septal Defects can occur alone or in combination with other congenital malformations.
  • Usually blood flows from the higher pressure left ventricle through the shunt to the lower pressure right ventricle. Left to right shunting causes volume overload of the pulmonary circulation and consequently the left atrium and ventricle. The consequences of L-R shunting are left sided congestive heart failure and pulmonary hypertension.
  • Shunting can be reversed from L-R towards R-L if pulmonary hypertension increases the pressure on the right side of the heart and/or there is also pulmonic stenosis (Eisenmengers's Physiology). A R-L shunt would allow unoxygenated blood into the systemic circulation resulting in arterial hypoxemia. Increased amounts of blood into the systemic circulation causes an increased right sided pressure load.

Diagnosis

History & Clinical Signs

-Coughing

-Exercise Intolerance

-Left-sided congestive heart failure

-Right-sided heart failure

-Cyanosis (with R-L shunt)

-Asymptomatic (small defects)

Physical Exam

-Holosystolic murmur over left apex and right sternal boarder

-Systolic murmur over pulmonic valve (pulmonic stenosis)

-Diastolic murmur over aortic valve (aortic regurgitation)

-Murmur from mitral regurgitation (caused by left ventricular dilation)

Radiographic Findings

Normal findings with small defects

Left to Right Ventricular Septal Defect

-Pulmonary overcirculation

-Left-sided heart enlargement

-Signs of left-sided heart failure

-Enlargement of pulmonary artery (if pulmonic stenosis is present)

-Right ventricular enlargement (seen with pulmonary hypertension)

Right to Left Ventricular Septal Defect

-Right-sided heart enlargement

-Normal to enlarged pulmonary artery

Echocardiographic Findings

-Visible defect in the intraventricular septum

Doppler confirms blood shunting through defect

Electrocardiographic (ECG)

-Left sided enlargement (L-R shunt)

-Right ventricular hypertrophy (R-L shunt)

-Arrhythmias

-Wide or notched Q wave showing abnormal septal depolarization

Treatment

Mild/Moderate Cases

-No treatment

-May close on their own

Severe Cases

Medications:

-Drugs to decrease volume through the shunt (arterial vasodilators for R-L shunt)

-Drugs to combat heart failure

Surgery:

-Surgical closure of the septal defect (open heart surgery rarely performed in veterinary patients)

-Pulmonary artery banding (Palliative surgical procedure to decrease left to right shunting)

  • Use of vasodilators and the surgical procedures above are contraindicated with a right to left shunt

Prognosis

Mild/Moderate Cases

-Excellent

Severe Cases

-Guarded (L-R shunts)

-Poor (R-L shunts)

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