Congenital Volume Overloads Flashcards
What is a patent ductus arteriosus?
- Persistent opening of the ductus arteriosus after birth
Who gets PDA?
- Toy breeds
- Herding breeds (Sheltie, Collie, Shepherd, Corgi, etc.)
PDA sex predilection
- Seen more commonly in female than male dogs
Pattern of inheritance for PDA
- Inherited
- Polygenic trait
How common is PDA?
- May be the most common dog defect
Ductus arteriosus function in utero
- Umbilical vein from the mother and skips liver through ductus venosus
- Comes into the caudal vena cava to right atrium
- Preferentially shunted through foramen ovalis into left atrium and left ventricle through aorta into head and body
- Deoxygenated blood from the head in the baby that mixes with oxygenated blood in the right atrium
- SHunted through tricuspid through pulmonary artery and into ductus arteriosus
Where is the ductus arteriosus?
- Junction of aortic arch and descending aorta and pulmonary artery
What is the point of the ductus arteriosus in the fetus?
- Don’t want venous admixure to go to the brain
PDA murmur PMI, timing, and quality
- PMI: Left heart base
- Timing: continuous murmur
- Quality: Continuous murmur
Femoral pulses of PDA
- Normal to HYPERKINETIC*
Jugular distensions/pulses with PDA
- None usually for distensions or pulses
Arrhythmias with PDA
- Pulse deficits
- Possible
What can cause the hyperkinetic or bounding pulses with a PDA?
- Pulse pressure = systolic - diastolic
- Diastolic pressures are much lower because it’s leaking backwards during diastole
- Normal is 120/80
- During a PDA can be 110/50
Radiographic findings of PDA
- Left atrial enlargement
- left ventricular enlargement
- Pulmonary arteries and veins will be enlarged
- Aorta enlarged
- MPA will be enlarged too
Why do the structures that get enlarged in a PDA get enlarged?
- Going through multiple times
- Aorta –> MPA –> arterioles –> capillaries –> main pulmonary vein
What type of hypertrophy occurs with PDA?
- Eccentric hypertrophy
- Volume overload
Echocardiogram with PDA
- Right heart will look small compared to the left heart because the left heart is so big
- Eccentric hypertrophy
- Try to use Doppler
- Continuous flow
What determines severity of PDA?
- Depends on size of PDA
- Larger hole means larger volume overload and larger workload
Surgical treatment of PDA
- Surgical ligation with thoracotomy
- Also invterventional closure with vascular access via the femoral artery
What other treatment may be necessary for PDA?
- Treat left-sided CHF if present
- Furosemide + ACE inhibitors +/- Pimobendan
What’s the priority for PDA treatment: Treat CHF or treat the PDA?
- Important to treat the left sided CHF FIRST
- No anesthesia, until the pulmonary edema is resolved
Description of interventional closure
- Track up the femoral artery
- Inject contrast to highlight the ductus
- measure the size of the hole
- Waist of the device expands the ductus
What is usually the smallest dog that can have an interventional closure?
- 2kg
Mortality associated with interventional closure
- Pretty significant mortality
- Success rates are surgeon dependent
- If they do a bad job, they could cause an embolism
Prognosis for PDA if they close the ductus
- CURATIVE!!!!
- Normal life expectancy
- +/- cardiac meds (usually no meds)
Prognosis of PDA without closure
- 50-60% develop CHF and die within 1 year
- 70-80% develop CHF and die within 2 years
VSD definition
- Incomplete formation of the interventricular septum resulting in a communication between the left and right ventricles
Who gets VSD?
- Most common congenital heart disease in all species except for the dog
Left ventricular pressure compared to right ventricular pressure
- LV: 120/6
- RV: 20/5
Mime the flow of blood from the left ventricle to the right ventricle with a VSD
- Just do it
VSD murmur PMI, timing, and quality
- Hear it on the right side better (often basilar)
- Systolic
- Ejection quality
What additional murmur can happen with a VSD?
- Aortic regurgitation
Aortic regurgitation murmur PMI, quality, and timing
- PMI is left heart base
- Quality is decrescendo
- Timing is Diastolic
Femoral pulse quality with VSD
- Normal
Jugular distensions or pulses with VSD
- None
Arrhythmias with VSD
- Possible
- Pulse deficits
Radiographic findings of VSD
- Left atrial and left ventricular enlargement
- Overcirculation of lungs
- Should not see main pulmonary or aortic involvement with VSD
What type of hypertrophy occurs with VSD?
- Eccentric hypertrophy
VSD echocardiogram findings
- Aortic regurgitation can happen
What determines severity of VSD?
- Size
- Larger hole = more volume overload = larger workload
For murmur with a VSD, will it be louder when it’s smaller or bigger?
- Louder when it’s smaller
- Again, severity does not correlate very well with the loudness of the murmur
Treatment and prognosis for a small VSD
- No treatment needed
- Normal quantity and quality of life
Treatment and prognosis for a large VSD
- May develop Left sided CHF at some point
- If they develop left sided heart failure, furosemide + ACE-inhibitor +/- Pimobendan if CHF develops
Surgical options for severe VSD
- Pulmonary artery banding (palliative)
- Open heart failure (people only)
- Interventional closure
What determines prognosis for VSD?
- Size of the defect
- Development of CHF
What is prognosis if an animal goes into stage C with VSD?
- ~ 1 year
Eisenmengers Physiology with VSD/PDA - initially
- Pulmonary overcirculation, resulting in pulmonary vascular hypertrophy and fibrosis
- Increased pulmonary pressures
- As long as systemic pressures are higher than pulmonary pressures, blood will go to the lungs first
- Make sure you can mime out where blood will go
Physiology of no shunt with a PDA or VSD
- Pulmonary pressures = systemic pressures
Right to left shunting pathophysiology of VSD and PDA
- Pulmonary overcirculation
- Pulmonary vascular hypertrophy and fibrosis
- Increased pulmonary pressures
- Eventually, pulmonary pressures > systemic pressures
- Right –> left shunting leading to deoxygenated blood in your body (AKA hypoxemia)
What secondary condition can occur with hypoxemia?
- Polycythemia
Pathophysiology of polycythemia secondary to right to left shunting
- Deoxygenated blood to systemic circulation
- Hypoxia
- Increased EPO secretion by the kidneys
- Polycythemia
- Hyperviscosity
What causes R–> L PDA?
- Reversal happens EARLY in life
- 1st couple of months
- Not a result of an uncorrected left to right PDA
- If you have a left to right, it will often just go into CHF
Findings for a R–> L shunt: murmur, jugular distension, and mucous membranes?
- Murmur: usually none, as blood is too viscous
- Jugular distension and pulsation: +/+
- Mucous membranes cyanotic, especially with exercise
On a PE, what would be different about the distribution of cyanosis for a R–>L PDA vs a R–>L VSD?
- THINK ABOUT IT
Treatment for right to left PDA
- CLOSURE IS CONTRAINDICATED (right heart failure because it has to work against an increased pressure)
- Treat polycythemia
How to treat polycythemia
- Phlebotomy (~20mL/kg q4-6 weeks)
- Medical treatment: sildenafil, hydroxyurea (bone marrow suppressor)
Prognosis for R–> L VSD or PDA
- Long term prognosis is guarded to poor
- Better with control of polycythemia
- Acceptable quality of life for ~5-10 years, but often quite high maintenance
Breeds that get tricuspid dysplasia?
- Lab!!!!!!**
- Danes
- Borzoi
- German Shepherd Dog
- Boxer
- Shih Tzu
- Mastiff
Breeds that get mitral valve dysplasia?
- Cats
- Bull Terrier*
- Labs
- Danes
- German SHepherd Dogs
Murmur PMI, timing, and quality for tricuspid dysplasia?
- Right apex
- Systolic
- Regurgitant
Murmur PMI, timing, and quality for mitral valve dysplasia?
- Left apex
- Systolic
- Regurgitant
Femoral pulses, jugular distension/pulses, and arrhythmias for tricuspid dysplasia?
- Femoral pulses: Normal
- Jugular distension/pulses: +/+
- Arrhythmias: pulse deficits
Femoral pulses, jugular distension/pulses, and arrhythmias for mitral valve dysplasia?
- Femoral pulses: Normal to weak
- Jugular distension/pulses: -/-
- Arrhythmias: pulse deficits
Severity of AV Valve dysplasia
- Varies greatly
- worse with larger regurgitant volume or of stenosis is also present
Treatment of AV valve dysplasia
- Treat CHF if present
- Treat arrhythmias
- Surgery not really an option for these guys
How to treat CHF for AV valve dysplasia?
- For either, furosemide + ACE inhibitors +/- Pimobendan
- For tricuspid valve dysplasia, abdominocentesis +/- thoracocentesis
What is the common arrhythmia with AV valve dysplasia?
- Atrial fibrillation
How to treat atrial fibrillation?
- Diltiazem (calcium channel blocker)
- +/- digoxin
Prognosis for AV valve dysplasia if mild
- Normal quantity/quality of life
Relative prognosis for TVD vs MVD
- TVD often fare better than MVD
Prognosis once you hit CHF
- ~ 1 year
- May be worse with atrial fibrillation
