Ch. 35 Cardiovascular Flashcards
Which type of dog b reeds appear to have smaller hearts due to their thoracic conformation?
The normal cardiac silhouette in breeds with a laterally compressed but deep thoracic cavity, such as greyhounds and collies, can look abnormally small. Image top to bottom: borzoi, lab, pug
Why is VHS potentially inadequate, compared to a subjective assessment?
- there is too much variation in normal (mean 9.7, range 8.7 - 10.7)
- variation of almost 1 vertebra in combinationo f resp and cardiac cycle
- variation in readers/measurements
mean overall (general non specific dog breeds) VHS
9.7 vertebrae
SD 0.5
range 95% within 2 SD: 8.7 - 10.7
2 causes (1 common, 1 less common) of LA dilation
- MMVD
- L to R pulmonary overcirculation
Why do dogs with dilated LA (but not in heart failure) cough?
LA impingement on a malacic bronchus with dynamic collapse; it is unlikely to cause narrowing on a healthy bronchus.
How might a dilated LA affect the tracheal bifurcation and principal bronchi?
- dorsal deviation of the bifurcation (lateral)
- divergence of the principal bronchi (DV/VD)
- if bronchomalacia, narrowing of the principal bronchi (lateral)
How to distinguish whether principal bronchi divergence is due to enlarged tracheobronchial lymph nodes or dilated LA?
use lateral projection; LA dilation is more ventral than tracheobronchial lymphadenomegaly
Concentric hypertrophy is a likely response to increased/decreased preload/afterload, such as ________.
increased afterload, e.g. for LV: aortic stenosis
enlargement of the craniodorsal aspect of the cardiac silhouette on a lateral projection can be due to: (3 things)
dilation of
- RA (on DV will be approx. 9-11 o’clock)
- AA
- MPA
Eccentric hypertrophy is a likely response to increased/decreased preload/afterload, such as ________.
increased preload, e.g. for LV: PDA, MVD/insufficiency
RV enlargement occurs mainly in the dog/cat.
dog
increased afterload causes
concentric hyoertrophy
concentric hypertrophy (at expense of lumen) occurs due to increased __
afterload
in the RV, hypertrophy is usually concentric/eccentric, e.g. due to _____
concentric; increased afterload e.g. pulmonic stenosis
What is the normal amount of cardiac contact with the sternum?
2.5 - 3 intercostal spaces
deep chested 1.5 - 2
barrel chested 3-3.5
sternal contact in excess of __ intercostal spaces is consistent with _____ enlargement
3, RV
what does the ‘valentine heart’ indicate in cats?
LA dilation
RL or LL?
LL
which rib do you compare the width of the caudal lobar artery?
9th
LL view; what is white arrow pointing to?
R cranial lobar artery
Which 4 types of conditions increase the size of both arteries and veins?
L > R shunts (PDA, VSD, ASD)
peripheral arteriovenous fistula
iatrogenic IV fluid overload
fluid retention 2’ to decreased cardiac output
conditions where only pulmonary arteries enlarge
Do primary thromboses cause enlargement of pulmonary veins or arteries?
arteries
conditions that cause only pulmonary vein (not artery) enlargement
condition that decrease the size of pulmonary arteries and veins
canine heartworm; enlarged cranial lobar pulmonary artery
canine heartworm; reverse D shape cardiac silhouette = RV hypertrophy
canine heartworm; enlargement of R caudal lobe artery