35. Cardiovascular system (+ extra bits) Flashcards by anna frykfors von hekkel

List three reasons why rx not accurate for cardiac evaluation

1) Variations in normal
2) Effect of positioning on appearance
3) Poor correlation between morphological and physiological abnormalities

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Which radiographic projections comparatively influence the appearance of the cardiac silhouette most profoundly? How / why?

DV vs VD

DV: Diaphragm billows forward, displacing heart cranially and to the left to a varying degree -> more pronounced in medium / large breeds

VD: Magnification of the heart in LARGE BREEDS due to distance from plate

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Describe the vertebral heart scoring system. Why is it used?

Theoretically allows normlisation for body size

Technique:

Measure long axis and short axis -> SUM
Measure from cranial margin of T4

Normal: 8.7-10.7 (Too variable!)

**Up to 1.0 may vary with cardiac / resp cycle**

=> Best used for serial images in same patient

DOES NOT PERFORM BETTER THAN QUALITATIVE

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What is the most common chamber dilation in the dog? Why?

LA -> Prevalence of MMVD

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Why does LA dilation result from L->R shunting?

Pulmonary overcirculation and VOLUME OVERLOAD

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In the DV projection, what structures are identified at the 12-1; 1-2; and 2-3 positions on the clock face? Where is the RA identified?

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Why do dogs with LAE cough?

Possibly some inpingment from LA BUT USUALLY DUE TO CHONDROMALACIA

-> NO association between canine CHF and coughing

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How can LAE and TB LN+ be distinguished?

BOTH cause divergence of prinipal bronchi

LAE: Ventral to bifurcation

TB LN: Dorsal to bifurcation (typically)

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List radiographic features of LAE in the dog

Lateral:

Dorsocaudal bulge

Flattening / concavity of caudal margin

Loss of cardiac waste

DV:
Divergence of principal bronchi

“Double wall” - appearance of enlarged LA superimposed on heart

L Auricular enlargement / displacement

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List radiographic features of LAE in the cat

**MAY APPEAR NORMAL**

Lateral:

Concavity of caudal margin

DV:
- Valentine shape heart -> Due to increased diameter of heart base. DOES NOT REFLECT BIATRIAL DILATION!!!!

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List features of LV enlargement (dog and cat same)

Lat:

Elongation -> Secondary elevation of trachea

=> Narrowing of angle between trachea and thoracic vertebrae

VD/DV:

Rounding of left heart border
Blunted apex

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Provide examples that cause LV eccentric vs concentric hypertrophy

Eccentric => INC PRELOAD

Concentric => INC AFTERLOAD

Ao Stenosis

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Cause of isolated RA enlargement?

RARE
Tricuspid dysplasia

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Rx features of RAE

Lateral:

Enlargement at craniodorsal aspect -> NOTE may reflect enlargement of aorta or MPA

DV/VD

9-11 o clock bulge

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Hypertrophy of which chamber may be identifiable radiographically?

RV -> More so than LV

Possibly due to thinner wall -> more obvious changes

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Define the amount of sternal contact described in normal dogs of different breeds

Deep chested (Dobi, wolfhound): 1.5-2 ICS

Average dog: 2.5-3 ICS

Barrel chested (bulldog): 3-3.5 ICS

>3 often described to support RV enlargement

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Rx features of RV Enlargement

Lat:

Increased sternal contact (Approx > 3 ICS)
Elevation of heart apex from sternum

DV/VD

Reverse D

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What 2 measures are used to determine CaVC enlargement?

diameter > length of 5th or 6th thoracic vertebral body
diameter > 1.5x descending Ao

=> NOTE: Variability with cardiac and resp cycle. Should be consistent finding

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Rx features of Ao enlargement

Lat:
- Inc. mass at craniodorsal aspect

VD/DV:

Widening of precardiac mediastinum
Focal bulge (e.g. Ao stenosis, PDA)
**BEWARE** older cats with tortuous Ao, may be projected laterally to left, and appear as pulmonary nodule

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Causes of RV hypertrophy

INC AFTERLOAD:

Pulm stenosis
Pulm hypertension (e.g. heartworm)

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Which projection is best used to evaluate the size of the cranial pulmonary arteries and veins?

LEFT LATERAL

=> in right lateral, often superimposed vessels interfere

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Which measures are used to evaluate peripheral pulm art and vvs?

Are they similar in size?
Relative to thickness of 9th rib

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BOX: Enlarged pulm a and v

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What is the most common cause of pulm art distension without vein?

Pulmonary hypertension 2ry to HEARTWORM

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BOX: Pulm art enlargement ONLY

What is the distribution of pulmonary vascular lesions most commonly seen in heartworm disease? What additional feature was commonly seen in cats with experimental heartworm?

- CAUDAL vessels typically - R caudal more common than L caudal =\> CAN AFFECT ANY VESSEL / ALL VESSELS \*\*50% cats had persistent Bronchointerstitial pattern\*\* Similar to asthma -\> consider these cases suspect

What is the most common cause of pulmonary TE?

- HEARTWORM (...according to this book from US..)

What is the reported progression of PTE?

- Heterogeneous pattern, becoming alveolar - MAY BE NORMAL - PERIPHERAL!

Typical radiographic features of heartworm?

- MPA / Pulmonary artery enlargement - Pulmonary vessel tortuousity, "truncation" or "Pruning" (abrupt termination) - RV enlargement - Evidence of PTE - Signs of R heart failure

What is the most common cause of pulm V enlargement only?

- Mitral valve disease

BOX: Enlargement of Pulm V ONLY

BOX: Reduced size of both Pulm art and vv

WHAT WORD SHOULD YOU USE WHEN DESCRIBING SMALL Vs and As?

HYPERLUCENT LUNG

Describe pathophysiology of left heart failure inc. radiographic appearance

- Reduced output -\> increased end diastolic pressire in LV - Flows back into LA and Pulm V (Rx: Pulm v distension) - Eventually, transudation -\> pulm parenchyma (Rx: Patchy unstructured interstitial pattern-\> alveolar) - Oedema: Patchy, FOCAL (43/61 in 1 study), often dorsocaudal, uncommonly perihilar! - \*\*MAY\*\* cause pulm arterial hypertension -\> backing up at capillaries, AND morphological changes to increase resistance to flow

How does mitral valve jet location effect oedema?

Central jet: Symmetrical pulmonary changes Eccentric: Assymetrical pulmonary changes

Features of R heart failure?

- Pleural effusion +- atelectasis - Hepatosplenomegaly - Ascites

What are the 3 most common acquired cardiac lesions in clinical practice?

- MMVD - Cardiomyopathy - Heartworm

What poorly understood phenomenon is observed in canine DCM?

- Mixed bronchointerstitial pattern (= atypical / peribronchial oedema) - \> More classically seen with inflammatory disease

List 4 breeds predisposed to DCM

- Doberman - G Dane - Cocker - Boxer

Rx features of DCM

- Normal! - Generalised cardiomegaly - LAE - Pulm V +- A dilation (artery likely due to retenion as a result of decreased renal perfusion, and activation of RAAS) - R failure - Mixed bronchointerstitial pattern

Rx features of HCM

- LAtrial enlargement (valentine) - NORMAL LV as usually concentric change - Pulm v distension (rarer in cats) - Pulm oedema - Pleural effusion

Rx features of pericardial effusion

- Globoid - Clearly marginated - May contact walls of thorax if +++ - R heart failure =\> if moderate may go undetected

Rx signs of PDA

- Dilation of proximal descending Ao - MPA and Pulm a + v enlargement - LA / auricular enlargement (Three knuckled appearance) - LV enlargement

Rx features of PS

- Dilation of MPA - RV enlargement - Normal / small pulm vessels (reduced CO)

What type of Ao Stenosis is most common?

SUBVALVULAR \> valvular

Rx features of Ao stenosis?

- DIlation of Ao arch - LV enlargement +- LA enlargement +- Pulm vessel enlargement (if mitral inufficiency) MAY BE NORMAL

Rx features VSD

DEPENDS ON VOLUME -\> Typically quite dorsal, so empty directly into MPA - Mild RV Enlargement +- mild pulm vessel enlargement

Rx features of tricuspid dysplasia

- RA enlargement +- small pulm vessels if poor CO

Causes of microcardia

- Hypovolaemia - Dehydration (chronic) - Metabolic disease -\> THINK ADDISONS!

Detail formation of the cardiac atria

Briefly, how does the interventricular septum form

Detail the early embryological structures of the heart

What do the endocardial cushions develop into?

- Left and right AV ostia

Embryology - PDA

Embryology - ASD

Embryology - PS

Embryology - AS

Embryology - AV dysplasias

Embryology - Endocardial cushion defects

Embryology - Conotruncal defects

Embryology - Tetralogy / pentatology

Embryology - NORMAL Aortic arch formation / other arteries

Embryology - MOST COMMON VASCULAR RING

Embryology - aberrant left subclavian

Embryology - DOUBLE AORTIC ARCH

Embryology - AORTIC COARCTATION

Embryology - Cor triatriatum. Which type is more common?

- Dexter more common

Embryology - Name the major embryological components forming the vena cava. Which components fail to regress in persistent left CrVC and in duplication of the caudal VC?

Label the major arteries

Describe species differences in arterial supply to the brain

List the 5 arteries supplying the different portions of the brain. Which vessels feed them?

Briefly, detail the vertebral / paravertebral venous system