Difference between revisions of "Ventricular Septal Defect"

Revision as of 10:39, 13 March 2011

Ventricular septal defect. Courtesy of A. Jefferies

Introduction

Ventricular Septal Defect, also known as VSDis the most common congenital cardiac abnormality in large animals and the second most common congenital cardiac abnormality in cat. It does occur in dogs, but less frequently. Predisposed breeds include Keeshonds, English Springer Spaniel, English Bulldog and West Highland White Terrier.

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 see below). 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. The defect is often associated with other conditions e.g. Tetralogy of Fallot.

Eisenmenger's Syndrome: chronic pulmonary overcirculation results in pulmonary hypertension and increased right-sided pressure. This facilitates right to left shunting and reduced lung perfusion, leading on to cyanosis.

Clinical Signs

Coughing, exercise intolerance, left-sided congestive heart failure, right-sided heart failure and cyanosis (with R-L shunt) are all possible clinical signs. With smaller defects, the condition can be asymptomatic.

Diagnosis

History and clinical signs would be presumptive of a heart condition.

On physical examination, a holosystolic murmur over left apex and right sternal border (diagonal murmur) can be detected as well as a systolic murmur over pulmonic valve (pulmonic stenosis) and diastolic murmur over aortic valve (aortic regurgitation). There may also be a murmur from mitral regurgitation (caused by left ventricular dilation).

Radiographs would show a generally normal heart with small defects such as pulmonary overcirculation, left or right sided heart enlargement (due to which side the shunt went) and enlargement of the pulmonary arteries.

Echocardiography with doppler would show blood shunting through defect.

An Electrocardiographic (ECG) will show left sided enlargement (L-R shunt), right ventricular hypertrophy (R-L shunt), arrhythmias and a wide or notched Q wave showing abnormal septal depolarization.

Treatment

treatment and may close on their own. Severe cases will usually need medications; drugs to decrease volume through the shunt (arterial vasodilators for R-L shunt) and drugs to combat heart failure. Surgery may also be necessary in these cases to close the septal defect (open heart surgery rarely performed in veterinary patients) or to perform pulmonary artery banding (palliative surgical procedure to decrease left to right shunting).

The use of vasodilators and the surgical procedures above are contraindicated with a right to left shunt.

Prognosis

In mild to moderate cases the prognosis is excellent. In severe cases, the prognosis is guarded (L-R shunts) and poor (R-L shunts).

References

Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.
Pasquini, C, Pasquini, S, Woods, P (2005) Guide to Equine Clinics Volume 1: Equine Medicine (Third edition), SUDZ Publishing.

Test yourself with the Developmental Pathology Flashcards

Cardiovascular Developmental Pathology Flashcards

@@ Line 1: / Line 1: @@
-[[Image:VSD1.jpg|right|thumb|125px|<small><center>'''Ventricular septal defect'''. Courtesy of A. Jefferies</center></small>]]
+[[Image:VSD1.jpg|thumb|right|125px|<small><center><b>Ventricular septal defect</b>. Courtesy of A. Jefferies</center></small>]]
-[[Image:VSD2.jpg|right|thumb|125px|<small><center>'''Ventricular septal defect'''. Courtesy of A. Jefferies</center></small>]]
+[[Image:VSD2.jpg|thumb|right|125px|<small><center><b>Ventricular septal defect</b>. Courtesy of A. Jefferies</center></small>]]
-Also known as VSD
+== Introduction<br> ==
-*Most common congenital cardiac abnormality in large animals
+Ventricular Septal Defect, also known as VSDis the most common congenital cardiac abnormality in large animals and the second most common congenital cardiac abnormality in cat. It does occur in dogs, but less frequently. Predisposed breeds include Keeshonds, English Springer Spaniel, English Bulldog and West Highland White Terrier.&nbsp;
-*Second most common congenital cardiac abnormality in cat
+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.&nbsp;On the left ventricle, the septal defect usually occurs under the aortic valve.&nbsp;
-*Occurs in dogs
+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.&nbsp;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 see below). 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. The defect is often associated with other conditions e.g. Tetralogy of Fallot.
-===Signalment===
+'''<br>'''
-Genetics & Predisposed Breeds: Keeshonds, English Springer Spaniel, English Bulldog, West Highland White Terrier
+'''Eisenmenger's Syndrome''': chronic pulmonary overcirculation results in pulmonary hypertension and increased right-sided pressure. This facilitates right to left shunting and reduced lung perfusion, leading on to cyanosis.
+<br>
-===Description===
+== Clinical Signs<br> ==
-*Ventricular defects are usually in the membranous area of the interventricular septum.
+Coughing, exercise intolerance, left-sided congestive heart failure, right-sided heart failure and cyanosis (with R-L shunt) are all possible clinical signs. With smaller defects, the condition can be asymptomatic.<br>
-*On the right ventricle, the septal defect usually occurs below the septal leaflet of the tricuspid valve.
+<br>
-*On the left ventricle, the septal defect usually occurs under the aortic valve.
+== Diagnosis<br> ==
-*Ventricular Septal Defects can occur alone or in combination with other congenital malformations.
+History and clinical signs would be presumptive of a heart condition. <br>
-*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.
+On physical examination, a holosystolic murmur over left apex and right sternal border (diagonal murmur) can be detected as well as a systolic murmur over pulmonic valve (pulmonic stenosis) and diastolic murmur over aortic valve (aortic regurgitation). There may also be a murmur from mitral regurgitation (caused by left ventricular dilation).
-*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.
+Radiographs would show a generally normal heart with small defects such as pulmonary overcirculation, left or right sided heart enlargement (due to which side the shunt went) and enlargement of the pulmonary arteries.
-===Diagnosis===
+Echocardiography with doppler would show blood shunting through defect.
-====History & Clinical Signs====
--Coughing
+An Electrocardiographic (ECG) will show left sided enlargement (L-R shunt), right ventricular hypertrophy (R-L shunt), arrhythmias and a wide or notched Q wave showing abnormal septal depolarization.
--Exercise Intolerance
+<br>
--Left-sided congestive heart failure
+<br>
--Right-sided heart failure
+== Treatment<br> ==
--Cyanosis (with R-L shunt)
+treatment and may close on their own. Severe cases will usually need medications; drugs to decrease volume through the shunt (arterial vasodilators for R-L shunt) and drugs to combat heart failure. Surgery may also be necessary in these cases to close the septal defect (open heart surgery rarely performed in veterinary patients) or to perform pulmonary artery banding (palliative surgical procedure to decrease left to right shunting).
--Asymptomatic (small defects)
+The use of vasodilators and the surgical procedures above are contraindicated with a right to left shunt.
-====Physical Exam====
+<br>
--Holosystolic murmur over left apex and right sternal border (diagonal murmur)
+== Prognosis<br> ==
--Systolic murmur over pulmonic valve (pulmonic stenosis)
+In mild to moderate cases the prognosis is excellent. In severe cases, the prognosis is guarded (L-R shunts) and poor (R-L shunts).
--Diastolic murmur over aortic valve (aortic regurgitation)
+<br>
--Murmur from mitral regurgitation (caused by left ventricular dilation)
+<br>
-====Radiographic Findings====
+== References<br> ==
-Normal findings with small defects
+Merck &amp; Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial<br>Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.<br>Pasquini, C, Pasquini, S, Woods, P (2005) Guide to Equine Clinics Volume 1: Equine Medicine (Third edition), SUDZ Publishing. <br>
-'''Left to Right Ventricular Septal Defect'''
+<br>
--Pulmonary overcirculation
+<br>
--Left-sided heart enlargement
+== Test yourself with the Developmental Pathology Flashcards ==
--Signs of left-sided heart failure
+[[Cardiovascular Developmental Pathology Flashcards]]
--Enlargement of pulmonary artery (if pulmonic stenosis is present)
+[[Category:Cardiovascular_System_-_Developmental_Pathology]] [[Category:To_Do_-_Cardiovascular]] [[Category:Cardiac_Diseases_-_Dog]] [[Category:Cardiac_Diseases_-_Cat]] [[Category:Cardiac_Diseases_-_Horse]] [[Category:Cardiac_Diseases_-_Cattle]] [[Category:Cardiac_Diseases_-_Pig]]
--Right ventricular enlargement (seen with pulmonary hypertension)
+<br>
-'''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)
-==From Pathology==
-[[Image:VSD1.jpg|right|thumb|200px|<small><center>'''Ventricular septal defect'''. Courtesy of A. Jefferies</center></small>]]
-Often associated with other conditions E.g. [[Tetralogy_of_Fallot|Tetralogy of Fallot]].
-Usually occur high in the membranous region of the interventricular septum.  Blood flows from left to right ventricle during systole resulting in right ventricular overload, increased central venous pressure and pulmonary overcirculation.<br>
-'''''Eisenmenger's Syndrome''''': chronic pulmonary overcirculation results in pulmonary hypertension and increased right-sided pressure.  This facilitates right to left shunting and reduced lung perfusion, leading on to cyanosis.
-''Incidence:''
-*Not common in dogs but increased incidence in WHWTs and Cocker Spaniels.
-*More common in cats and cattle.
-''Clinical Signs:''
-*Depend upon size of defect, may include; exercise intolerance, venous congestion etc.
-*Harsh holosystolic murmur.  Murmur grade correlates inversely with the defect size.
-''Diagnosis:''
-*Left and right ventricular hypertrophy, often generalised cardiomegaly on radiology and ECG.
-*Pulmonary overcirculation on radiology.
-*Left ventricle hyperkinetic on echocardiography and often the defect may be visualised.  Doppler echocardiography may be useful.
-[[Image:VSD2.jpg|right|thumb|200px|<small><center>'''Ventricular septal defect'''. Courtesy of A. Jefferies</center></small>]]
-*Mitral regurgitation is common due to a change in size of the left ventricle and consequent alterations to the Mitral valve.
-''Treatment:''
-*Small defects require no treatment.
-*'''Pulmonary Banding''' protects the pulmonary circulation by restricting its blood flow.
-*Symptomatic therapy for left heart failure E.g ACE inhibitors.
-*Prognosis variable with defect size.
-==Test yourself with the Developmental Pathology Flashcards==
-[[Cardiovascular Developmental Pathology Flashcards]]
-[[Category:Cardiovascular_System_-_Developmental_Pathology]]
-[[Category:To_Do_-_Cardiovascular]]
-[[Category:Cardiac Diseases - Dog]][[Category:Cardiac Diseases - Cat]][[Category:Cardiac Diseases - Horse]][[Category:Cardiac Diseases - Cattle]]
-[[Category:Cardiac Diseases - Pig]]