SA Approach to the Cardiac Patient

Question 1

1. What cardiac disease type do we expect to see in young animals?
2. What cardiac disease type do we expect to see in adult animals?
3. What feature of cardiac diseases makes diagnosis easier in vet med?
4. Important physical exam finding to pick up on.

Answer 1

1. Congenital cardiac diseases.
2. Acquired cardiac diseases.
3. The strong breed predispositions.
4. Arrhythmias – not always indicative of heart disease and not all heart disease patients present with arrhythmias.

Question 2

Thoughts for when the patient is presented.

Answer 2

• Age, breed (large, small).
• CHF classic signs for right and left sided.
• Gathering history w/ questions:
  – when did it start?
  – Weakness, exercise intolerance, syncope?
  – Respiration (cough – note not directly related to heart failure).
  – Inappetence?
  – Weight gain (ascites)?

Question 3

1. Signs of left sided heart failure.
2. Signs of right sided heart failure.
3. Signs of reduced CO related to heart failure.

Answer 3

1. Pulmonary oedema - tachypnoea, dyspnoea.
2. Distended peripheral veins - ascites, pleural effusion.
3. Weak peripheral pulses.
   Cold extremities
   Tachycardia.

Question 4

Initial body response to heart failure.

Answer 4

Activation of SNS.
- Tachycardia (B1).
- Vasoconstriction (a1) – increase afterload.
Renin-angiotensin-aldosterone-system.
- Na, water retention, increase blood volume and preload.
- Vasoconstriction – increase BP and afterload.
- Vasopressin – increase blood volume (preload and afterload).
- Remodelling – hypertrophy (increased contractility), fibrosis etc.
- Body trying to increase heart contractility by stretching cardiomyocytes, but these eventually fail.

Question 5

1. Body condition of patient in heart failure.
2. Respiration of patient in heart failure.
3. Normal sleeping RR in the dog.
4. CHF RR in dog.

Answer 5

1. • Cardiac cachexia.
     - Abdominal distension.
2. • RR and effort increase.
     - Dyspnoea, (cough).
3. Up to 30 breaths/min.
   Most between 7-20 breaths/min.
   Day to day variability.
4. > 35-40 breaths/min.

Question 6

1. MM findings in CHF patient?
2. Palpate what on the thorax?
3. Check what on the neck?

Answer 6

1. Pink, moist, CRT <2sec.
   Important to compare the cranial MMs w/ the caudal MMs.
2. Apex beat of the heart.
3. Jugular distension.

Question 7

Thoracic auscultation.

Answer 7

• Quality.
• HR:
  – Dogs = 80-160/min, cats = 120-240/min (180/min).
• Rhythm – regular, irregular, gallop sound.
• Intensity – quiet/dull, loud.
• Pulse quality compared w/ auscultation:
  – weak, strong, deficits.
• Lung field: resp. sounds.

Question 8

Heart murmurs.

Answer 8

Timing - systolic, diastolic, continuous (most in SA are systolic).
Point if maximal intensity - apex, base, left, right.
Grading (1-6):
- louder does not necessary mean more severe disease.
- Can have physiological flow murmurs – pups and kittens.
- Anaemic murmurs.
- Athletic animals can have murmurs.

Question 9

Heart murmur grading 1-6.

Answer 9

1. Very quiet, takes time to localise.
2. Quiet, less loud than heart sounds.
3. Obvious, as loud as heart sounds.
4. Louder than heart sounds.
5. Very loud, w/ precordial thrill.
6. Very loud, thrill, audible lifting stethoscope off chest.

Question 10

1. Localisation of heart murmurs.
2. On auscultation, where would you locate a PDA?

Answer 10

1. Left cranial = Aortic, pulmonic.
   Left caudal = Mitral (left AV).
   Right cranial = Ventricular septal defect (sternal), aortic.
   Right caudal = Tricuspid (right AV).
2. More dorsal and more cranial than aortic and pulmonic valves.

Question 11

Diagnostic tests.

Answer 11

• Echocardiography – Dx, severity.
• Thoracic radiographs – Heart size, CHF.
• ECG – Arrhythmias.
• BP – Hypertension, hypotension.
• Blood tests – Electrolytes, kidneys, cardiac biomarkers.

Question 12

Echocardiography.

Answer 12

• Dx of cardiac disease.
• Severity of disease.
• Treatment options.
• Progression of disease.
• Response to treatment.

Question 13

Thoracic radiographs.

Answer 13

• In cases of dyspnoea, tachypnoea, cough.
• Diagnostic test of choice for left sided CHF.
• Size of heart:
  – vertebral heart sum (dogs<10.7), LA.
  – Trachea, sternal contact.
  – Caudal vena cava.
• Lung fields.
• Pulmonary vessels.

Question 14

Left sided CHF on radiograph.

Answer 14

Peri-hilum caudal and dorsal.
Spread more cranially if more severe.
Interstitial pattern initially.
Then alveolar pattern as gets worse.

Question 15

Cardiomegaly on thoracic radiograph.

Answer 15

Very enlarged left atrium.
Very enlarged heart.
Trachea pushed up towards spine.

Question 16

Lung ultrasound.

Answer 16

Less specific than radiography.
SAFER in dyspnoeic patients.
“Dry” lungs - reverberation artefacts (A lines), rib shadows = “gator sign”.
“Wet” lungs - e.g. pulmonary oedema, pneumonia, haemorrhage, etc.
- comet tail artefacts down the screen rather than across

Question 17

ECG.

Answer 17

Indicated if find bradycardia, tachycardia, irregular rhythm, pulse deficits.
To diagnose arrhythmias.
24hr ECG recording (Holter).
- intermittent arrhythmia (syncope, weakness).
- severity of arrhythmia.
- diagnosis of cardiac disease (DCM, ARVC).
- response to treatment.

Question 18

BP.

Answer 18

Hypertension: systemic pressure increase.
Increased afterload, increased work/oxygen demand.
Heart failure:
- reduced forward SV.
- hypotension (<80mmHg).
*normal systolic BP = 120-140mmHg.

Question 19

Blood tests.

Answer 19

Haematology = inflammation (sepsis)?, anaemia (murmurs)?
Biochemistry:
- electrolytes – RAAS, vasopressin.
–> Na, K, Cl: hypokalaemia, hyponatraemia.
- Renal values:
– urea, creatinine: pre-renal azotaemia.
- ALT – liver perfusion.

Question 20

Cardiac biomarkers.

Answer 20

Cardiac troponin I (intracellular) – cardiomyocyte damage.
NT-proBNP – increased filling pressures.
BUT non-cardiac diseases and physiological factors can result in increased biomarker concentrations.

Question 21

1. Aim of treatment of left-sided heart failure.
2. Treating hypoxia.
3. Treating pulmonary oedema.
4. Treatment to improve contractility.
5. Minimising stress.

Answer 21

1. Inotropic support, pre- and afterload reduction.
2. O2 supplementation.
3. IV furosemide.
4. Pimobendan.
5. Sedation (btorphanol).

Question 22

Diuretics.

Answer 22

Furosemide:
- most important drug.
- NaKCl pump of ascending LoH.
- Rapid and potent, IV vasodilation.
- IV (IM, SC, PO) 2mg/kg every 1-4hrs.
Torasemide:
- longer half life, more potent.
- Anti-aldosterone?, initial drug?, dose?, PO – not great in emergencies.

Question 23

Pimobendan.

Answer 23

Phosphodiesterase 3 inhibitor (cAMP), Ca sensitizer.
Inotropic, vasodilation, anti-remodelling.
Dogs in CHF in combination:
- improves life quality and quantity.
PO or IV (expensive) (in emergency).
Cats w/ systolic dysfunction.

Question 24

Pre- and afterload, remodelling.

Answer 24

ACE inhibitor:
- Benazepril, enalapril, ramipril.
- inhibits conversion Angiotensin I to II.
- vasodilation, inhibits Na and water retention, anti-remodelling.
Spironolactone:
- aldosterone inhibitor.
- anti-remodelling, weak K-sparing diuretic.

Question 25

Treatment follow-up.

Answer 25

• Monitor RR.
• Water ad lib, food ASAP.
• Home ASAP.
• Life long treatment:
  – dogs: furosemide, pimobendan, ACE inhibitor, spironolactone.
  – cats: furosemide, clopidogrel (pimobendan, ACE inhibitor, spironolactone).
• Bloods and BP 5-7d after start of treatment/dose changes.
• Approximately 3 months after, in for blood tests and BP, ECG (if arrhythmia), thoracic radiography (tachy/dyspnoea), echocardiography (progression).