Canine Congenital Heart Disease: An Update on Medical and Interventional Management
1. Interventional Management of Congenital Heart Disease
Transcatheter occlusion of PDA's
Gianturco coil vs. vascular occlusion devices
Arterial vs. venous method of occlusion
Balloon valvuloplasty
Pulmonic stenosis
Aortic stenosis
Mitral / tricuspid valve stenosis
Cor triatriatum
Diagnostic cardiac catheterization
Open heart surgery program
Scheduled to begin in 2008
2. Canine Congenital Heart Disease
Morphologic defect of the heart or great vessels that is present at birth
Not synonymous with heritable
Prevalence: 0.5-0.85%
Complex deformities rare
3. Classification
Acyanotic shunting lesion (L-R)
Patent ductus arteriosus (PDA)
Ventricular septal defect (VSD)
Atrial septal defect (ASD), patent foramen ovale
Atrioventricular canal defects
Nonshunting lesions
Obstructive (pressure overload)
Aortic, subaortic stenosis (SAS)
Pulmonic stenosis (PS)
AV valve stenoses
Regurgitant (volume overload)
AV valve dysplasia
Cyanotic shunting lesions (R-L)
Tetralogy of Fallot
Right to left PDA
Eisenmenger's syndrome
R-L VSD or ASD due to PH
Rare congenital defects
Cor triatriatum dexter / sinister
Great vessel lesions
Truncus arteriosus / pseudotruncus
Transposition of the great arteries
4. Diagnostic Approach to CHD
Physical examination
Thoracic radiographs
ECG
Primarily useful for arrhythmia detection
+/- chamber enlargement
Echocardiogram
Presence and severity of defect
Non invasive estimation of PG across lesions/ valves
Positive contrast echocardiography
"Bubblegram"
Cardiac catheterization & angiography
Used to complete diagnostic workup
Used prior to interventional techniques to better qualify / quantify the defect (s)
Requires fluoroscopy
C arm
Used in CHD cases to obtain diagnostic information about the heart & great vessels
Identify lesion location, quantify severity
Angiographic studies
Left heart: aorta, coronary arteries, LA, LV
Right heart: Vena cava, RA, RV, pulmonary arteries
Pressure studies: catheters can be used to measure pressures in the cardiac chambers, great vessels, pulmonary arteries and pulmonary capillaries
"Pressure waveforms" are created
Right heart catheterization
Assess MPA pressure, RV, RA pressures
Assess location and severity of PS lesion
Assess pulmonary capillary wedge pressure (PCWP) >>> mean LA pressure
Assess for fixed pulmonary hypertension
(Eisenmenger's physiology)
Assess shunting defects
Left heart catheterization
Assess coronary artery anatomy
Assess/quantify shunting lesions
Assess LV and aortic pressures
5. Indications for Cardiac Catheterization in CHD
Assessment of valve and chamber anatomy
Diagnostic and therapeutic catheterization
Balloon dilation
Device placement
Coronary angiograms: coronary artery anomalies
Shunt detection and quantification prior to intervention
Oximetry (quantitative)
Angiography (qualitative)
Therapeutic cardiac catheterization
Therapeutic intervention: Successful management of cardiac disease through a minimally invasive approach
Balloon valvuloplasty
PDA transcatheter occlusion
Septal defect closure ??
6. Cardiac Catheterization: Complications
Arrhythmias
Intracardiac damage/perforation
Blood clots in the catheter
Artery or vein damage
Hematoma, hemorrhage at incision site
Angiograms: Excessive contrast use
7. Patent Ductus Arteriosus
Signalment and presentation
Puppy to young adult
Female > male
Predisposed breeds
Asymptomatic if small PDA
Large shunt: clinical signs of LCHF
Reversed PDA (right to left shunting PDA)
Weakness, cyanosis
Physical exam
Left basilar continuous murmur
+/- bounding pulses ("waterhammer")
Due to diastolic "run off" causing increased pulse pressure
Clinical sequelae: Dependant on shunt size
Left sided CHF
Irreversible myocardial failure
Reversal: right to left shunt
Diagnostics: Radiographs
LA and LV enlargement
Aortic ductal aneurysm and MPA bulge
Pulmonary overcirculation
ECG: Tall R waves
Echocardiogram
LA/LV volume overload +/- myocardial failure
PDA visualization: anatomy and flow
Medical management: Short term
Furosemide
ACE inhibitor
Surgical ligation
Transcatheter occlusion: Device options: Gianturco coil, VOD, ACDO
Transcatheter occlusion--Complications
<1% mortality
Hemorrhage
Perforation of the aorta
Damage to peripheral vessel
Coil embolization
Pulmonary artery (pulmonary hypertension may result)
Lungs
Aorta (celiac / mesenteric arteries)
Residual flow
Hemoglobinuria (transient)
2nd procedure
VMTH: <4%
Medical treatment for longstanding PDA
Manage CHF: diuretics, ACEI
Atrial fibrillation: digoxin +/- diltiazem
Myocardial failure: Older patients or patients with large shunts that have been overlooked
Pimobendan therapy: Stabilizes patient, improves outcome long term for chronic PDA cases
Goals: PDA closure !!!!
Reduce volume overload, wean off diuretics
+/- continue Pimobendan and antiarrhythmics
8. Subaortic Stenosis (SAS)
Discrete, fixed fibrous or fibromuscular ridge or ring of tissue
Subvalvular
Valvular AS uncommon
Fixed outflow tract stenosis
LV concentric hypertrophy
Coronary lesions
Myocardial fibrosis
Ventricular arrhythmias
Diastolic dysfunction
Large breed dogs
Likely heritable
Progressive lesion for first 12 months
PE: left basilar systolic ejection murmur
"Pulsus parvus et tardus"
Arrhythmia
Clinical signs / sequelae
Exercise intolerance
Arrhythmias
Collapse /syncope
Sudden death
Left sided CHF ( esp. if concurrent MVD)
Valvular endocarditis
Diagnostics
Thoracic radiographs: Variable
ECG: Tall R waves, arrhythmias
Echocardiogram
Current treatment options
Cardiac catheterization rarely used: further diagnostic information
Surgical management: variable effectiveness
Open heart resection: requires CPB
Septal myectomy
Alcohol ablation of septal hypertrophy
Balloon dilation of stenosis
Acute hemodynamic improvement
Questionable reduced risk of sudden death
No clear benefit over medical management
Medical management
Beta blockade: Atenolol therapy
Antiarrhythmics, Diuretics, ACEI PRN
Prophylactic Abs
9. Pulmonic Stenosis (PS)
Signalment and presentation
Small breed dogs
Often asymptomatic
CS: exercise intolerance / collapse
Obstructive lesion / stenosis
Secondary RV concentric hypertrophy
Valvular, supravalvular , subvalvular
PE: Left basilar systolic murmur
Normal femoral pulses
+/- jugular pulses, arrhythmia
Clinical signs / sequelae
Exercise intolerance
Syncope
Ventricular arrhythmias
Atrial fibrillation
Right sided congestive failure
Cyanosis if R-L shunt present
Rarely sudden death
Diagnostics
Thoracic radiographs: MPA bulge, reverse "D"
ECG: Deep S waves
Echocardiogram
"Bubblegram" : assess for R-L shunt
Interventional management: Cardiac catheterization
Angiographic evaluation of pulmonic valve anatomy/lesion
Obtain pressure waveforms
+/- coronary angiography
Balloon valvuloplasty
Moderate /severe valvular PS
If ASD or PFO present
If significant TR present
PS: Complications
Variable pulmonic insufficiency
Transient or permanent RBBB
Transient arrhythmias
Cardiac perforation
Significant tricuspid valve damage
Other management options: Dysplastic, hypoplastic valves
Surgery via "inflow occlusion"
Valvulotomy
Patch graft technique
RV to PA conduit
Medical management : Beta blocker
Symptomatic treatment for CHF if present
Antiarrhythmic therapy PRN
10. Atrioventricular Valve Dysplasia
Mitral valve dysplasia (MVD)
Regurgitation >> Stenosis
Bull terriers ( mitral stenosis)
Large breed dogs
Tricuspid valve dysplasia (TVD)
Regurgitation >> stenosis
Labrador Retrievers
German Shepherds, Golden Retrievers
Likely heritable
Physical examination
MVD: left apical systolic +/- diastolic heart murmur
C/S of left sided CHF
TVD: right apical systolic +/- diastolic heart murmur
C/S of right sided CHF
Both MVD and TVD
Variable exercise intolerance +/- syncope
Due to low cardiac output (associated with valvular stenosis or tacharrhythmias)
Diagnostics
Thoracic radiographs: Variable
ECG : Atrial arrhythmias common
Echocardiogram: Definitive diagnosis
AVV Dysplasia: Options for management
Balloon dilation of stenotic valve
Surgery
Inflow occlusion and valvulotomy for TVD
MVD or TVD: CPB and valve repair/replacement
Only mature dogs >10kg
Expense
Limited surgical experience
Lifelong anticoagulant therapy
Medical: Tx CHF and atrial dysrhythmias
Diuretic, ACEI
Antiarrhythmics: rate control
Pimobendan therapy: improve cardiac output
11. Left to Right Shunts
Direction and magnitude of shunt
Size of communication
Relative resistance to flow downstream
Most common: PDA ( as described above ) , VSD, ASD
VSD: Clinical presentation: Dependant on VSD size
Restrictive (small): asymptomatic
Nonrestrictive: LA/LV volume overload causing symptoms of left sided CHF
Physical examination
Right sided systolic ejection murmur
+/- weak arterial pulses
VSD: Pathophysiology: Determination of degree of shunting
Diagnostics
Thoracic radiographs : Pulmonary overcirculation
ECG
Echocardiogram: Visualize defect and degree of volume overload
Interventional and medical management
Tx for left sided CHF: diuretics, ACEI
Tx atrial dysrhythmias
Surgical management
MPA banding (palliative)
Open heart repair
Interventional management
Future of closure with Amplatzer devices
Primary difficulty: relation of VSD to aortic valve
Atrial septal defect (ASD)
Usually clinically insignificant
Most patients are asymptomatic
Exceptions include: large ASD's, R-L shunts, and AV canal defects
L-R shunts
Soft left basilar systolic ejection murmur
Variable left heart volume overload
R-L shunts
Occur with pulmonic stenosis or PH
Interventional and medical management
Medical management of L CHF
Intervention: ASD closure
Amplatzer device
Surgical closure via suture or patch
12. Right to Left Shunts
Most common: Tetralogy of Fallot, R-L PDA
Eisenmenger's Physiology: Large, nonrestrictive VSD (Large PDA, ASD or AV canal) leading to irreversible pulmonary hypertension
Clinical presentation
Moderate to severe exercise intolerance
Cyanosis
Stunted growth
Physical exam
Tetralogy of Fallot: left basilar systolic murmur due to PS
Eisenmenger's patients: no heart murmur
Diagnosis via contrast echocardiogram : aka: "Bubblegram"
R-L shunting defects: Options for management
Surgical repair of Tetralogy of Fallot (rare)
Palliative shunt (T of F)
Redirect blood from left subclavian into pulmonary artery (Blalock-Taussig shunt)
Balloon dilation of pulmonic stenosis (T of F)
May create large L-R shunt and CHF
Medical management
Phlebotomy with IV fluid replacement
Hydroxyurea
Sildenafil (Viagra)
+/- beta blockers
13. Cor Triatriatum Dexter
Congenital lesion: partitioning of the right atrium into two chambers by a fibromuscular membrane
Clinical signs of RHF at very young age
Echocardiographic diagnosis
Cardiac catheterization: Right heart: locate defect, obtain pressure tracings
Angiogram: Location of membrane and perforation
Cor Triatriatum Dexter: Management
Long term medical management
Diuretics and frequent abdominocentesis
Unrewarding, progressive RHF
Surgical management: Invasive
Thoracotomy
Requires inflow occlusion
Balloon dilation via cardiac catheterization
Variable to good success
May need to repeat procedure
Future Possibilities...