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
canine compensated MVD; cardiomegaly, LA dilation, R caudal pulmonary artery enlarged
In which lateral view does dorsal displacement of the cardiac apex mean RV hypertrophy (in the other view can be seen in normal dogs)?
Right lateral
What is a common cause of generalised cardiomegaly?
DCM
What can artifactually cause generalised cardiomegaly?
underinflation
what appearance does the heart have with hypertrophic RV on DV/VD projections?
reverse D
when is the CVC considered enlarged?
If the diameter is consistently:
- > length of T5/6 (lateral)
- > 1.5x descending aorta
A focal bulge in the descending aorta in VD or DV views can be seen in patients with ________ and _______.
aortic stenosis, patent ductus arteriosus
An enlarged CVC can indicate increased central venous pressure - T or F
It does increase in size in response to this, but this is not an accurate way of diagnosing this.
What is the significance of a tortuous aorta in older cats?
clinically insignificant
The main pulmonary artery is not seen normally as a separate structure, but when it dilates sufficiently in dogs, it will appear as a focal bulge in the ____ o’clock position in _____ views.
1
VD/DV (not routinely visible in laterals)
Why is MPA dilation rarely seen in cats?
rarely recognized in cats. This is not because it does not occur but because the enlarged artery does not extend peripheral to the cardiac silhouette in cats as in dogs
Common causes of MPA dilation:
- pulmonary hypertension e.g. heartworm
- turbulence, e.g. pulmonic stenosis or PDA
‘veins are ventral’ applies mainly to which lobar pulmonary veins?
cranial, because the caudal lobar arteries and veins are superimposed in lateral
The right cranial lobar vessels are best seen as individual structures when the animal is in____ lateral recumbency.
left
Peripheral pulmonary arteries should be approximately (size-wise):
- same as the associated pulmonary vein
- same as R9 thickness at intersection on VD/DV
why are the right cranial lobar vessels better for assessment than the left?
because the left overlap in RL, whilst the right are distinguishable in LL
in which view are the caudal lobar vessels better assessed and why?
DV, better lung inflation
and more perpendicular to XR beam
The bronchus is the space between the artery and vein - true or false?
why do arteries enlarge in heartworm disease?
pulmonary hypertension from lesions in the tunica intima (proliferation) or media (Hypertrophy) – and/or — thromboembolic disease
Give an example each of a medication/therapy that would cause pulmonary vessel to be smaller or enlarged
small - diuretic > dehydration
large - overzealous IVFT
what’s the most common cause of pulmonary arterial enlargement (no venous enlargement) in dogs?
heartworm infection
Which radiographic changes might persist following resolution of vascular changes of feline heartworm?
bronchointerstitial pattern
which arteries enlarge in canine heartworm disease?
any or all; usually caudal lobars and more commonly R caudal
_________________ can represent the earliest radiographic change seen in spontaneous feline heartworm disease
Enlargement of the caudal lobar arteries on the VD view, with normal-sized caudal pulmonary veins
_____________ is also the most common cause of pulmonary thromboembolism (and why).
Heartworm disease
arterial occlusion by: dying worm emboli or blood clots
Pulmonary vein enlargement is most commonly seen in dogs with _____________ because of _____________.
mitral insufficiency
pulmonary venous hypertension
pathophysiology of congestive L-sided heart failure
increase in end-diastolic filling pressure LV
> LA > pulmonary veins (hypertension)
> transudate (aka pulmonary edema)
Pulmonary vessel tortuosity in dogs is most commonly associated with __________.
heartworm disease
typical distribution of cardiogenic pulmonary edema in dogs
caudodorsal (but any distribution is possible)
does arterial or venous hypertension occur in L-CHF?
both; venous then arterial as a consequence of venous and later, capillary changes
typical distribution of cardiogenic pulmonary edema in cats
patchy +/- pleural effusion
Right-sided heart failure findings (XR):
- bilateral pleural effusion (+/- secondary pulmonary atelectasis)
- ascites
- hepatosplenomegaly
Mitral valve disease
- small or large dogs?
- volume or pressure overload?
- distended veins, arteries or both?
- left or right CHF changes?
small
volume
veins, then arteries in late stages
left
heartworms are normally located in the
pulmonary arteries
XR changes in heartworm
- LV or RV hypertrophy?
- dilation of MPA or AA?
- enlargement of arteries or veins?
- L or R CHF?
RV
MPA
arteries
R-CHF
2 parenchymal sequelae of heartworm
PTE
pneumonitis (allergic)
breeds predisposed to DCM
Doberman, Great Dane, Cocker spaniels, Boxers
Radiographs can be normal in dogs with DCM - true or false
true
DCM cardiomegaly is caused by ______ overload or _______ dilation
volume, ventricular
why would LA be dilated in DCM?
either volume overload, or change in shape of the mitral annulus (as the heart dilates) which causes mitral valve dysfunction
Are arteries be dilated in DCM?
Can be - from fluid retention secondary to decreased renal perfusion which activates renin-angiotension system
Which is common in DCM - L or R-CHF changes?
R-CHF
How might L-CHF manifest on XR in dogs with DCM?
bronchointerstitial pattern (instead of typical caudodorsal alveolar)
HCM is a feline-only disease - T or F
F, just rare in dogs
Which chamber is hypertrophied in HCM?
LV
Radiographic findings of feline HCM
- LA dilation (valentine heart)
- early: pulmonary vein enlargement
- L-CHF: pulmonary edema
- late: pleural effusion
pericardial effusion may cause _____ (L or R) CHF due to _____.
R-CHF, if pericardial tamponade is severe enough to prevent RA/RV filling
PDA
- where is the communication
- which direction is the shunt
- between descending aorta and MPA
- aorta > MPA
Which areas enlarge from PDA?
- proximal descending aorta (focally, due to turbulence)
- MPA
- LA
- LV
- pulmonary A and V
pulmonic stenosis - where is the stenosis
pulmonic valve - between RV and MPA
what enlarges with pulmonic stenosis
MPA (turbulence > dilation)
RV (increased resistance > hypertrophy)
appearance of pulmonary parenchymal vasculature in PDA
normal, unless R-CHF develops, in which case smaller due to decreased cardiac output
which type of aortic stenosis is more common?
subvalvular
what structures enlarge with aortic stenosis?
- aortic arch (dilates due to turbulence)
- LV (hypertrophy due to increased resistance)
- IF mitral valve dysfunction develops > LA +/- pulmonary venous congestion/hypertension
Where are VSDs typically located?
dorsal in the membranous septum, just below aortic valve
which direction is shunt in VSD? in which cycle?
LV > RV (systole only)
in diastole, similar pressures
Where does shunted blood go in VSD?
LV to RV, however since usually very dorsal, goes immediately into MPA
which has more blood volume shunting - PDA or VSD?
PDA (although depends on size of defect in VSD)
Tricuspid dysplasia causes which structures to change size?
- RA - enlarged (pressure/volume overload)
- pulmonary vessels can become smaller if cardiac/RV output decreases
what structures are enlarged in VSD?
- RV (hypertrophy - volume and pressure overload); usually mild
- pulmonary A + V can be normal or enlarged due to a mild/mod increase in blood flow volume
