Cardiology

Question 1

Define pulmonary hypertension

Answer 1

Pulmonary arterial systolic pressure >30 mmHg

Question 2

Name 3 mediators of pulmonary vasoconstriction

Answer 2

Alveolar hypoxia, endothelin-1, and thromboxane A2

Question 3

Name two mediators of pulmonary vasodilation

Answer 3

Prostacyclin, nitric oxide (NO)

Question 4

Vasoconstrictors tend to have what effect on platelets?

Answer 4

Platelet agonists that promote coagulation (thromboxane A2)

Question 5

How does nitric oxide promote vasodilation? What limits it’s action?

Answer 5

NO activated cGMP => vasodilation. Phosphodiesterase 5 (PDE5) inactivates cGMP to limit vasodilation

Question 6

What is the mechanism of action of sildenafil?

Answer 6

Phosphodiesterase 5 (PDE5) inhbitor => vasodilation/prolonged vasodilation

Question 7

What are the six classifications of pulmonary hypertension? Give an example for each

Answer 7

1. PH due to pulmonary arteriolar vascular disease (idiopathic, congenital systemic to pulmonary shunts, genetic disease)
2. PH due to pulmonary venous hypertension (left sided heart disease)
3. PH with pulmonary disease/hypoxia (pulmonary fibrosis, neoplasia, edema)
4. PH due to thromboembolic disease (PTE)
5. Parasitic disease (heartworm, Angiostrongylus)
6. Miscellaneous or multifactorial (compression due to neoplasia)

Question 8

Peak regurgitant flow velocity of the tricuspid valve can be used estimate pulmonary arterial pressure. What is the equation?

Answer 8

pressure gradient = 4 x (peak velocity)2

Question 9

Name 3 other echocardiographic findings in pulmonary hypertension

Answer 9

RV concentric/eccentric hypertrophy, RA enlargement, septal flattening, RV systolic dysfunction, enlargement of the pulmonary artery

Question 10

Definitive diagnosis of pulmonary hypertension would require what diagnostic?

Answer 10

Right heart catheterization and direct pressure measurements

Question 11

While treatment with sildenafil has been shown to improve clinical signs and QOL, it may not improve what?

Answer 11

Pulmonary arterial pressure (as estimated by tricuspid valve regurgitation). Depends on the study. One study showed improvement (83 to 55mmHg)

Question 12

What drug may be used instead of sildenafil and has a longer half life (q24 hour dosing)?

Answer 12

Tadalafil

Question 13

In dogs with congenital shunts or left sided heart disease, sildenafil should be used with caution. Why?

Answer 13

Can lead to acute pulmonary edema

Question 14

Cardiac troponin n is a biomarker of what?

Answer 14

Cardiac cellular injury

Question 15

In one study of dogs with PH due to respiratory disease, how many dogs died within one month? 50% mortality was reached when?

Answer 15

32% died in the first month. 50% by 6 months after diagnosis

Question 16

Of dogs with bronchomalacia, what percent had an intermediate or high probability of PH?

Answer 16

40%

Question 17

What is pulmonary veno-occlusive disease?

Answer 17

Occlusive remodeling of small and medium pulmonary veins

Question 18

What is pulmonary capillary hemangiomatosis?

Answer 18

An angioproliferative disorder characterized by proliferation of alveolar capillaries, which may infiltrate into pulmonary veins and bronchioles

Question 19

What is the typical signalment of dogs with either pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis

Answer 19

Older, present with acute respiratory signs (typically respiratory distress)

Question 20

What is the typical survival time of dogs with either pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis?

Answer 20

3 days median survival

Question 21

Where in the USA is dirofilariasis predominantly found? Which geographic location particularly?

Answer 21

The southeast and mississipi river valley region

Question 22

Outline the main lifecycle stages of dirofilariasis in the dog include timings.

At what stage can signs of HWD be seen?

Answer 22

1. Adults live in the pulmonary artery where they can release microfilaraise into the circulation.
2. Mf moult through L1 to L3 in the mosquito over 8 - 17 days. This is dependent on Wolbachia and temperature.
3. In the dog the L3 larvae go to L4 then S5 in the SQT, adipose or skeletal muscle.
4. S5 enter the circulation before setting up as adults

3 & 4 takes around 6 - 7 months.

HWD can be seen 2 - 3 months post infection when the S5 larvae enter the circulation. (so prior to ability to detect infection)

Question 23

At what time of day and season are heartworm Mf released?

Answer 23

During the evening hours and summer months

Question 24

Which lung lobes are most affected by heartworm proliferation? What is the histologic main mechanism of heartworm disease?

Answer 24

Myointimal proliferatoin of the vasculature is the histologic change. The caudal lung lobes seem to be most affected.

Question 25

What are the main mechanisms contributing to development of PHT in canine heartworm disease.

Answer 25

1. Release of vasoactive substances by heartworms 2. Production of ET-1 by the vasculature 3. Platelet activation 4. Hypoxia

Question 26

What are the main pathophysiologic consequences of canine HWD?

Answer 26

Vascular - resulting in PHT PTE (often in response to worm death) Glomerulonephritis (due to immune complex deposition) Abherrent migration through other tissues Eosinophilic lung disease

Question 27

How can Mf from D. immitis be distinguished from D. reconditum? - Number - Motion - Shape - Length

Question 28

What is the diagnostic approach to the detection of heartworm?

Answer 28

1. Perform antigen test 2. If positive then perform modified Knott test to look for Mf a) If negagative then start a preventative, doxyclycline and melarsomine after 2 months b) If positive then do as above but also clear microfilaraie prior to melarsomine 3. If negative then either this is a true negative but if clinical suspicion remains high then serum should be heat-treated.

Question 29

Which heartworm preventative is licenced for microfilarae?

Answer 29

Imidacloprid and moxidectin

Question 30

What stage of the HW lifecycle is heart worm prevention most targeted at?

Answer 30

Mostly targets L3 - L4 moulting

Question 31

Outline the adulticidal protocol for canine heart worm infection

Question 32

What is caval syndrome?

Answer 32

A syndrome of cardiogenic shock resulting from heavy heartworm burden. Features: 1. Haemoglobinuria is the pathognomonic feature 2. Haeolytic anaemia 3. Cardiac arrythmias

Question 33

What is the treatment of choice for heart-worm associated caval syndrome?

Answer 33

Removal of the worms from the pulmonary artery surgically.

Question 34

What is the main difference between canine and feline heartworm consequences?

Answer 34

Feline heartworm infections are unccomon. Although they can get the more classical HWD like dogs this occurs uncommonly. Usually they get HARD which is characterised by the abscence of female worms.

Question 35

How is feline HARD diagnosed?

Answer 35

By demonstrating antibody in the abscence of antigen. antigen positivity is associated with the presence of adult worms and therefore chronic HWI.

Question 36

What is the most sensitive marker of feline HARD on radiography?

Answer 36

he most sensitive marker is left caudal pulmonary artery greater than 1.6x the ninth rib at the ninth intercostal space on the VD projection (only present in 53% of cases).

Question 37

How is feline HWD treated?

Answer 37

Adulticides are a last resort so use macrocyclic lactones.

Question 38

What are the 5 Ps of ischaemic neuromyopathy?

Answer 38

Pain Paralysis Pulselessness Palor Poikilothermy

Question 39

Streptokinase - MoA - Side effects How does urokinase differ?

Answer 39

Activates plasmin through binding to plasminogen and production of plasmin activator complex. Side effects can include antigenic stimulation (as it is derived from streptococci), acute respiratory distress (cats), bleeding and reperfusion injury. UK has a similar mechanism of action but acts more specifically on fibrin bound plasminogen than free plasminogen. N.b that it is associated with very high mortality rates.

Question 40

Hepatin MoA

Answer 40

Binding and activation of ATIII which inhibits IIa, Xa, IXx and XIIa +/- inhibition of vWF

Question 41

How are drugs like heparins ideally monitored

Answer 41

Measurement of anti-Xa activity.

Question 42

What does this image show?

Answer 42

A peritoneopericardial mesothelial remnant - suggests PPDH

Question 43

What are the most common causes of pericardial effusion?

Answer 43

Neoplasia with HSA being most common Idiopathic pericarditis

Question 44

How does the predilection of heamangiosarcoma, chemodectoma and mesothelioma differ in pericardial disease?

Answer 44

HSA = RA Chemodectoma = heart base Mesothelioma = may not have a mass

Question 45

What is electrical alternans?

Answer 45

Variation in QRS complex height that appears regularly and is sometimes seen with pericardial effusions.

Question 46

What chemotherapy agents can be used in patients with mesothelioma?

Answer 46

Intracavity cisplatin +/- intravenous doxorubicin

Question 47

What is the MST of heart base mass tumours compared to HSA when causing pericardial effusion?

Answer 47

With a heart base mass a subtotal pericardectomy can prolong survival (up to 730 days!) compared to not having surgery (42 days)

Question 48

How does the aitiology of pericardial effusion differ between dogs and cats?

Answer 48

In dogs the vast majority of cases are caused by neoplasia. In cats the majorty are due to CHF, followed by neoplasia. In cats the neoplasia is rarely primary cardiac.

Question 49

What are the 6 factors that can result in oedema formation?

Answer 49

1. Intravascular hydrostatic pressure 2. Extravascular hydrostatic pressure 3. Intravascular oncotic pressure 4. Interstital oncotic pressure 5. Vascular permeability 6. Lymphatic function

Question 50

Outline starlings equation

Answer 50

Q = K[(Pmv − Ppmv) − (pmv − ppmv)], where Q = net transvascular fluid flow, K = membrane permeability, Pmv = hydrostatic pressure in the microvessels, Ppmv = hydrostatic pressure in the perimicrovascular interstitium, pmv = plasma protein osmotic pressure in the circulation, and ppmv = protein osmotic pressure in the perimicrovascular interstitium.

Question 51

Which image here (top or bottom) illustrated bigeminy vs. a couplet?

Question 52

What do the following aspects of the ECG trace illustrate: a) P-wave b) PR interval c) Q d) R e) S f) T

Answer 52

a) Atrial depolarisation b) Conduction of impulse accross the AV node c) Ventricular septal depolarisation d) Left ventricular depolarisation e) The last bit of LV depolarisation (changes direction as direction of travel is away from lead 2) f) ventricular repolarisation

Question 53

How to calculate heart rate and instantaneous rate on ECG

Question 54

outline einthovens triangle

Question 55

Mobitz type 1 AVB vs. type 2 AVB

Answer 55

1 = Progressive prolongation of the PR interval - this is not pathologic and an atropine response test is indicated 2 = Set PR inverval with dropped beats - pathologic

Question 56

Difference between RBB and LBB?

Answer 56

Left will be upright QRS in lead II (think about an L)

Question 57

What are the main radiographic features of canine HWD?

Answer 57

1. Prominance of the main pulmonary artery 2. RV hypertrophy 3. Large pulmonary artery and tortous or pruned pulmonary artery