Cardiovascular Flashcards
What are the most common indications for pacemaker implantation in dogs?
What are some less common uses for pacing therapy in dogs?
- High grade second degree AV block (3:1 conduction or less)
- Third degree AV block
- SSS
- Atrial standstill
NB: cats with AVB have faster V escape rhythm 90-120bpm so don’t typically require pacemaker.
Less common:
- Vasovagal syncope
- Chronic supraV tachyarrhythmias refractory to medical management (AFib, re-entrant A arrhythmias, ATach) - combo radiofreq ablation then pacing
- Refractory V tachyarrhythmias (e.g. long QT) - combo pacemaker + intracardiac defibrillators (case reports in dogs)
What is the incidence of sudden death in dogs with high grade AV block without pacemaker?
Up to 40% within 6 months of diagnosis
MMVD: What clinical signs have been identified as negative prognostic indicators?
- cough,
- exercise intolerance,
- decreased appetite,
- breathlessness/difficulty breathing
- syncope
- Mumur > III/VI
- absence/loss of respiratory sinus arrhythmia
MMVD: What other changes (apart from clinical signs) have been associated with higher risk of CHF?
- increase NT-proBNP
- enlarged heart size
- LA enlargement
How is PV/PA measured?
- Right parasternal long view
- trace line perpendicular to the medial PV passing through the center
- Use M mode to measure inner edge to inner edge at the end of the T wave
What is tissue Doppler imaging-derived E/Emsept a predictor of?
Load independent CHF in dogs with MMVD
What is tissue doppler imaging (TDI)?
Form of doppler that measures the velocity of the heart muscles through different phases of the cardiac cycle.
TDI measures the excursion of the myocardium, rather than the blood flow. TDI is less load dependent than the transmitral flow pattern.
What does the E/Emsept measure?
Ratio of the transmitral peak early diastolic velocity to the tissue doppler-derived peak early diastolic velocity at the interventricular septal basal segment
La:Ao greater than what value is associated with worse outcomes in dogs with MMVD?
> 1.7
La:Ao greater than what value is associated with worse outcomes in dogs with MMVD?
> 1.7
What proportion of dogs with MMVD stage B2 have pulmonary hypertension?
Approx 1/3
What % of puppies have an innocent murmur?
What are the characteristics of this?
What may explain the presence of an innocent murmur?
15%
Systolic, musical, maximum 2/6 intensity, PMI left cardiac base
Anaemia was noted in these and may contribute to initial murmur that resolves with age and improvement in HCT.
what changes are expected to be seen on echo after PDA closure?
- reduced preload
- reduction in LVIDd
- reduced La:Ao - Transient reduction in LV systolic function
- reduced FA
- LV dyssynchrony
At what cut off, what is the sensitivity and specificity of NTproBNP for discriminating between CHF and non-cardiac resp distress in dogs?
> 2447 pmol/L
sens 81%
spec 73%
- Describe the pathogenesis of patent ductus arteriosus (PDA).
- What is proportion of dogs & cats with congenital heart defects have PDA?
- ductus arteriosus is a vessel that develops from the embryonic
left sixth aortic arch. Typically, ductal flow decreases dramatically
within the first 12 hours of life in the neonatal dog, ceasing altogether
within 7 days, but in some individuals the ductus can remain patent.8
Direction of blood flow through the PDA is determined by the relative
resistances of the pulmonary and systemic vascular beds. Flow therefore
typically proceeds from left-to-right, that is, from the aorta to the
pulmonary artery. - Dogs: 11-30%, cats: 3%
- How does a reverse (right to left) PDA develop?
- What proportion of dogs and cats patients develop this?
- What are the treatment implications for reverse PDA?
Greet JVIM 2021
1. In animals with severe pulmonary hypertension, pulmonary vascular resistance can exceed systemic vascular resistance, leading to right-to-left shunting across the PDA, and mixing of deoxygenated blood in the descending aorta.
Increased
endothelial shear stress due to augmented pulmonary blood flow can
result in reactive vasoconstriction, progressive medial hypertrophy,
intimal proliferation of the pulmonary vasculature, and shunt reversal
(Eisenmenger’s physiology)
- 1-6% dogs with PDA. Cats»_space; common, 15-17%.
*NB: spectrum of disease - blood flow through the PDA can be continuously right-to-left or bidirectional, influenced by severity of PHT & SVR.
- PDA ligation is contraindicated
What does the E/A wave represent and what is a normal ratio?
In what pathological conditions will the E/A wave be unmeasurable?
E = peak velocity of blood flow across mitral valve in EARLY diastole (think E = early)
A = peak velocity of blood flow across mitral valve in LATE diastole (think A = after)
Also usually assess E wave deceleration.
Normal cats/dogs – E/A should be >1 (think E = Everest so should be higher). E/A ratio can decrease with age (can sit around 1 in older dogs).
When you cannot measure E/A ratio:
- Very fast HR e.g. cats. If cannot evaluate E/A ratio, likely some diastolic dysfunction. Measure isovolumic relaxation time (IVRT) instead as not affected by HR. Increased LA pressure shortens IVRT.
- AFib –> loss of A wave
With myocardial stiffening and delayed relaxation (e.g. HCM cats) –> decreased in E velocities.
Name conditions associated with:
a) HCM phenotype (cats)
b) DCM phenotype (cats)
c) DCM (dogs)
ACVIM Feline CM consensus 2020
a) Transient myocardial thickening (TMT), neoplastic infiltration, acromegaly, hyperT
b) Dietary taurine deficiency, tachycardia-mediated
c) Breed-specific gene mutations, taurine deficiency (American Cockers), toxins (doxorubicin), infectious (parvovirus infx @ 2-4wks old)
Which cat breeds are at-risk for HCM development?
Which associative gene mutations?
ACVIM Feline CM consensus 2020
Maine Coon, Ragdoll, British Shorthair, Persian, Bengal, Sphynx, Norwegian Forest cat, Birman.
Maine Coons homozygous for MYBPC3-A31P mutation
Ragdolls homozygous for MyBPC3-R820W mutation
Dog breeds predisposed to DCM?
Boxers (some have dietary carnitine deficiency)
Doberman Pinschers (not taurine-deficient)
Dalmations
Cocker Spaniels
NB: American Cockers - taurine deficient DCM (defects in taurine metabolism)
Golden Retrievers
Great Danes (not taurine-deficient)
Irish Wolfhounds Newfoundlands
Portuguese Water Dogs (juvenile form - onset several wks old)
Standard Schnauzers
Gene mutations associated with DCM in dogs?
German short-haired pointers - DMD
Dobers - PDK4, locus on chromosome 5
Boxers - STRN
Irish Wolfhounds - polymorphisms on chromosomes 1, 10, 15, 17, 21, 37
Normal LA pressure in dogs?
<10mmHg
What are the actions of Angiotensin 2? What receptor does it act on?
Acts on angiotensin receptor type 1 –> causes potent vasoconstriction, Na & H2O retention, aldosterone release, myocardial remodeling.
What was the major findings of the FAT CAT trial?
Hogan 2015 (J Vet Cardio)
Clopidogrel was shown to be superior to aspirin with :
- A lower FATE recurrence rate of 49% (vs 75%) & 1-year recurrence rate of 36% (vs 64%).
- Longer median time to FATE event (443 days) cf aspirin (192 days).
What was the major findings of the FAT CAT trial?
Hogan 2015 (J Vet Cardio)
Clopidogrel was shown to be superior to aspirin with :
- A lower FATE recurrence rate of 49% (vs 75%) & 1-year recurrence rate of 36% (vs 64%).
- Longer median time to FATE event (443 days) cf aspirin (192 days).
What major and minor criteria are included in the modified Duke criteria to diagnose infective endocarditis in dogs? What constitutes a definitive vs possible diagnosis?
Definitive dx = 2 major OR 1 major + 2 minor. Possible = 1 major + 1 minor OR 3 minor.
MAJOR:
- Echocardiographic valve lesion with typical characteristics of endocarditis:
– Oscillates independently of valve motion
– Associated with atrial aspect of mitral valve or ventricular aspect of aortic valve
- Positive blood cultures:
– ≥2 positive blood cultures
– ≥3 with common skin contaminant
- Evidence of new valve insufficiency
MINOR:
- PUO
- SAS (esp Boxers)
- Evidence of embolic signs
- - Evidence of systemic IMD
- Med-large breeds (>15kg)
- Positive blood cultures not meeting major criteria
- Bartonella spp serology ≥1:1024
