Cardiac emergencies I

Question 1

The three main determinants of the heart’s work:

Answer 1

cardiac preload
cardiac afterload
myocardial contractility

Question 2

Cardiac preload is

Answer 2

the amount of ventricular stretch at the end of diastole, the filling of the ventricles.

can be called “venous return” as well but is not so accurate cause preload isn’t venous return alone, it also includes ventricular wall compliance.

Question 3

Cardiac afterload is

Answer 3

The pressure that the heart must work against to eject blood during systole.

Question 4

Preload is affected by: (3)

Answer 4

venous return
compliance of ventricular wall
circulating blood volume

Question 5

Factors affecting cardiac afterload: (5)

Answer 5

Systemic hypertension
(Aortic valve will not open until the pressure generated in the left ventricle is higher than the elevated pressure in the aorta.)

Aortic stenosis
Aortic regurgitation
Mitral regurgitation
Alpha-2-agonists (vessel constriction)

Question 6

Contractility equals the

Answer 6

Ability of the heart muscle to eject a stroke
volume at a given prevailing afterload.

Question 7

Contractility is Affected by: (5)

Answer 7

morphology of the myocardium
sympathetic activation
drugs
parasympathetic activation
hypercapnia

Question 8

Heart disease versus heart failure

Answer 8

Heart disease = any structural abnormality in the heart that does not necessarily cause heart failure.

Heart failure=- a pathophysiological condition in which the heart is unable to function at a level that ensures adequate perfusion of organs and tissues.

Question 9

Heart failure pathophysiology can be divided into two broad groups:

Answer 9

volume overload issues

and

diastolic disorders

Question 10

volume overload issues in heart failure can be caused by: (3)

Answer 10

Systolic dysfunction (DCM makes systolic contraction insufficient)

Valvular insufficiency (leaky valve means some blood squirts back in making it too much total volume)

Left to right shunt (PDA = persistent ductus arteriosus)

Question 11

diastolic disorders in heart failure can be caused by: (3)

Answer 11

• Thick and rigid ventricular walls (diastolic relaxation is insufficient, blood backs up and causes left atrial dilation/hypertrophy and effusions further up the chain)
• Abnormal ventricular relaxation
• Pericardial problem

Question 12

Name the 4 main Cardiac Emergencies in Small Animals

Answer 12

Congestive heart failure
Cardiac tamponade

Arrhythmogenic disease
Thromboembolic disease

Many of these diseases are life threatening and must be diagnosed quickly and efficiently to provide relief of symptoms and to avoid delays in definitive treatment.

Question 13

Left atria size compared to left ventricle?

Answer 13

Atria should be max 1/3 the size of the ventricle.

Question 14

Low output or forward heart failure refers to when

Answer 14

The heart cannot provide blood flow adequate for metabolic demands.

Weakness and collapse

Question 15

Congestive heart failure or– backward failure refers to when

Answer 15

Increased venous pressure causes fluid accumulation in lungs or body cavities.

Breathlessness

Question 16

Congestive heart failure is characterized by 3 main features.

Answer 16

Poor myocardial contractility
Chronic cardiac overload
Cardiac injury

Question 17

Congestive heart failure Three phases:

Answer 17

1. initiating cardiac injury or insult (often undetected)
2. phase of compensation, but with clinically silent progression
3. the onset of clinical CHF signs

Question 18

Congestive heart failure Categories: (4)

Answer 18

Primary myocardial failure
Volume overload

Systolic pressure overload
Reduced ventricular compliance

But the distinctions between them blur
with disease progression and patients with advanced heart failure develop features of several categories.

Question 19

Common causes of congestive heart failure in dogs:

Answer 19

Degenerative mitral valve disease (MVD) (cavalier, yorkie etc.)
Dilated cardiomyopathy (DCM) (great dane, dobermen, boxer etc.)

Other causes can be:
infectious endocarditis
cardiac neoplasia
heartworm disease

Question 20

Common cause of congestive heart failure in cats:

Answer 20

Hypertrophic cardiomyopathy (HCM)

Other causes can be:
infectious endocarditis
cardiac neoplasia
heartworm disease

Question 21

History/anamnesis in congestive heart failure cases may include: (7)

Answer 21

may or may not have a history of a previous cardiac problem

may or may not be on medications

may have a dry and harsh cough, especially at night, in the early morning or after exercise

may be restless at night
exercise intolerance

syncope
weight loss

Question 22

Heart disease predisposition in what breeds?

Answer 22

Small breed dogs:
- Cavalier King Charles Spaniels
- Dachshunds
- Miniature and Toy Poodles

Cats:
- Maine coon

Large breed dogs:
Doberman Pinscher and
Boxer have a higher predisposition for
cardiomyopathy, which leads to heart failure.

Question 23

connection between dental health and heart disease

Answer 23

animals with very poor teeth have a constant state of inflammation in the gingiva. bacteria constantly enter the blood stream from the bad mouth = constant bacteremia.

bacteria can lodge in different organs, including the heart, leading to endocarditis which is heart valve inflammation, which in turn can lead to degeneration over time and an audible murmur.

Question 24

Why might a heart disease dog cough more in the mornings?

Answer 24

During the day time the heart may be compensating with a higher heart rate but over night the HR decreases so once the animal begins to wake up and move around in the morning, the compensation has not been “on” meaning it may exhibit signs such as cough.

Question 25

Common Clinical signs of heart failure. (7)

Answer 25

cough (dog)
dyspnea

lethargy
syncope or episodic weakness

abdominal distention (dog)
partial to complete anorexia

most cats in HF do not present for cough or
abdominal distention

Question 26

what is sinus rhythm on an ECG?

Answer 26

its sinus when each P wave has a QRST complex

Question 27

Dogs with HF secondary to MVD typically have what types of audible changes?

Answer 27

loud systolic murmurs and tachycardia (>120 bmp).

The absence of a murmur or a soft murmur (grade II or less) or the presence of a respiratory sinus arrhythmia in a
small-breed dog with respiratory signs usually refutes the diagnosis of HF.

Question 28

Dogs with DCM typically have what types of audible changes?

Answer 28

soft or barely audible systolic murmurs and tachyarrhythmias.

Question 29

Answer 29

atrial fibrillation in a dog or cat with suspect HF, is very suggestive of HF

Question 30

The physical examination of a cat with HF can unfortunately be

Answer 30

somewhat nonspecific.

The heart rate can be fast, normal, or slow.
Up to 30% of cats may not have an obvious arrhythmia, murmur, or gallop.

Cats in HF are not uncommonly hypothermic.

Question 31

empiric therapy in heart disease cases.

Answer 31

In some patients with significant respiratory distress, empiric therapy to stabilize patients is started even before any further diagnostic tests are performed if the signalment, history, and physical examination are suggestive of HF.

Initial empiric therapy typically includes:
- administration of parenteral furosemide
- oxygen
- sedation

Question 32

Diagnostics in cases presenting with overt heart disease.

Answer 32

The TFAST and AFAST ultrasound and focused echocardiogram are performed with patients in sternal recumbency while receiving oxygen supplementation typically after a low dose of sedation.

The examination is brief and minimally stressful to patients and is generally less stressful than performing a thoracic radiograph.

Goals:
- identifying pleural and pericardial effusions
- left atrial enlargement

Question 33

Focused thoracic ultrasound is especially useful in

Answer 33

cats with suspect HF because both the physical examination and radiographic findings in cats with HF are notoriously nonspecific.

Cats with HF usually have With pleural effusion, and in that case the heart can be clearly visualized by ultrasound, allowing accurate assessments of chamber dimensions, specifically left atrial size.

Question 34

a common manifestation of feline HF

Answer 34

Pleural effusion, a common manifestation of feline HF, obscures the cardiac silhouette, lungs, and vasculature radiographically.

With pleural effusion, the heart can be clearly visualized by ultrasound, allowing accurate assessments of chamber dimensions, specifically left atrial size.

Question 35

A left atrium/aorta ratio of 2.0 or greater is very suggestive of

Answer 35

HF.

The left atrium is most commonly indexed to the aorta in a right-sided, short-axis view at the base of the heart or a long-axis view.

Normally, the left atrium/aorta ratio is less than 1.5 in cats and less than 1.3 in dogs.

Question 36

Thoracic radiographs in Left-sided HF:
(3)

Answer 36

Dorsal displacement of trachea
Prominent pulmonary veins
Pulmonary edema

(interstitial pattern in image)

Question 37

Thoracic radiographs Right-sided HF:
(3)

Answer 37

Pleural effusion
Enlarged caudal vena cava
Hepatomegaly

Question 38

Use what for assessment of cardiomegaly.

Answer 38

Vertebral heart score (VHS)

Question 39

Cardiac biomarkers (2)

Answer 39

Cardiac biomarkers are blood tests for heart disease.

pro B-type natriuretic peptide (NTproBNP)
cardiac troponin I (cTnI)

Question 40

NTproBNP is

Answer 40

a peptide hormone released by the ventricles in response to increased stretch elevated in dogs and cats with active congestive HF.

used as an early cardiac biomarker (snaptest).

Question 41

proBNP SNAP test (cats)
Can be used when

Answer 41

Can be used when testing “suspicious”
patients (for example, pedigree cat,
breathing problem).

Negative SNAP – heart disease is unlikely

Positive SNAP without clinical signs– HCM
is possible – send to a cardiologist

Positive SNAP with signs of dyspnea –
handled as a patient with heart failure.

NB May give false positive results!

Question 42

Treatment of cardiac emergency.

Answer 42

The immediate goal of emergency therapy is to reduce abnormal fluid accumulations and to provide adequate or improved cardiac output.

Supplemental oxygen (cage/incubator or nasal catheter)

Sedation if needed

If the patient is dyspneic and anxious

Butorphanol is very effective 0.1 – 0.2 mg/kg.

Place an intravenous catheter, treat with furosemide and/or vasodilators if appropriate.

Additional treatments:
possible thoracocentesis
abdominocentesis
bronchodilators
antiarrhythmic agents

Question 43

Treatment with Furosemide

Answer 43

is a loop diuretic, is a mainstay in the management of congestive HF, regardless of the cause.

Despite its usefulness in HF
management, furosemide never technically improves cardiac output - it reduces volume overload.

Question 44

Describe Treatment using Pimobendan.

Answer 44

0.25 – 0.3 mg/kg q 12 h

dual mechanism of action (inodilator = dilates coronary vessels) calcium-sensitizing drug that improves contractility (positive inotrope) with minimal effects on myocardial oxygen consumption.

phosphodiesterase inhibition, primarily leading to a balanced vasodilation (arterial and venous) the role of pimobendan in feline HF is still evolving, typically added when a cat with HF has left ventricular systolic dysfunction, significant pleural effusion, renal insufficiency, or severe refractory pulmonary edema.

will NOT work in cats with hypertrophic heart disease.

Question 45

Vasodilators that may be used in cardiac emergent cases: (3)

Answer 45

Amlodipine 0.05 – 0.1 mg/kg PO

Nitroglycerine 2% ointment – transdermally

Enalapril 0.5 mg/kg PO q12 h

Additional treatments:
possible thoracocentesis
abdominocentesis
bronchodilators
antiarrhythmic agents

Question 46

Cardiac tamponade/ Pericardial effusion is

Answer 46

Physiologic state in which the pericardial effusion causes an increase in intrapericardial pressure resulting in impaired ventricular filling and low
cardiac output.

Question 47

The most common cause of pericardial effusion in older dogs is

Answer 47

neoplasia, most commonly right atrial
hemangiosarcoma in large-breed dogs and
chemodectomas (heart base tumors) in
brachycephalic dogs.

Question 48

The most common cause of pericardial effusion in cats is

Answer 48

CHF.

Question 49

Clinical signs of Cardiac tamponade/pericardial effusion. (7)

Answer 49

collapse
lethargy

exercise intolerance
cough/retching

shortness of breath
abdominal distention
inappetence

Question 50

Physical examination in pericardial effusion. (4)

Answer 50

muffled heart sounds
Tachycardia

weak pulse
pulsus paradoxus

Question 51

Pulsus paradoxus =

Answer 51

paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure (a drop more than 10 mmHg) and pulse wave amplitude during inspiration.

Normally, blood pressure drops less precipitously than 10 mmHg during inhalation.

Pulsus paradoxus is a sign that is indicative of several conditions, most commonly pericardial effusion.

Question 52

Diagnostics for suspected pericardial effusion.

Answer 52

Echocardiography is the most sensitive and specific modality. You cannot confirm pericardial effusion with xray, xray can only give you a suspicion of it.

• amount and echogenicity of the pericardial fluid
• thickness of the pericardium
• presence of a cardiac tumor

Diastolic right atrial and sometimes ventricular collapse.

Question 53

ECG abnormalities in pericardial effusion. (2)

Answer 53

sinus tachycardia
low amplitude QRS

Question 54

Treatment of pericardial effusion and tamponade.

Answer 54

Pericardiocentesis is the only effective treatment of immediate relief of cardiac tamponade.

Do NOT give furosemide in pericardial effusion. Why? Because diuretics and vasodilators may be harmful because they will reduce ventricular filling and cause further hypotension with hypovolemia.

Question 55

In which cardiac emergency should you most definitely NOT give furosemide?

Answer 55

in pericardial effusion!

Why?
Because diuretics and vasodilators may be harmful because they will reduce ventricular filling and cause further hypotension with hypovolemia. -> death.

Question 56

Describe Pericardiocentesis procedure

Answer 56

Mild sedation is sometimes needed.
Some patients are so hemodynamically compromised that sedation is not necessary. Patients are placed in sternal or lateral recumbency.

ECG should be performed during the procedure to monitor for ventricular arrhythmias.

The pericardiocentesis site is prepared aseptically. Lidocaine is infused at the puncture site on the RIGHT hemithorax between the third and sixth intercostal
spaces just above the costochondral junction.

Ultrasound or thoracic radiography is helpful to find the best site for the pericardiocentesis.

A 3-mL syringe is attached to the end of the
catheter and constant negative suction is applied.

Once in the pericardial space, the catheter is advanced over the needle stylet and extension tubing, a 3-way stopcock and 60-mL syringe are attached, and drainage of the fluid begins.

Question 57

Why is pericardiocentesis prognosis poor in dogs compared to cats?

Answer 57

Because in dogs, pericardial effusion is usually due to heart neoplasm but in cats its usual due to CHF which is more treatable than heart cancer.

Question 58

Why is pericardiocentesis performed on the RIGHT hemithorax and not on the left?

Answer 58

On the right side of the chest, the heart’s anatomical layout positions major coronary vessels (like the left coronary artery) and structures such as the left atrium away from the insertion site.

By accessing the pericardium from the right side, veterinarians reduce the risk of accidentally puncturing these critical structures, which could cause severe complications.

The left side of the chest houses the larger lung lobe and major structures like the aorta and the esophagus.

Entering from the left could risk lung puncture or damage to these adjacent structures. The right side provides a clearer path to the pericardial sac with fewer obstructions.

Question 59

Most pericardial effusions are haemorrhagic and can be similar in appearance to blood.

If there is concern for possible intracardiac
puncture, a sample of the fluid should be
obtained and visualized for clot formation.

Why?

Answer 59

Pericardial effusion should not clot.

If there are clots - then you’re in the heart.