Veterinary Cardiology - Failing Hearts

Failing Heart 2 - Learning Outcomes

• Describe the diagnostic approach for failing hearts and expected outcomes
• Outline an evidence-based treatment plan for congestive heart failure, aligning with ACVIM consensus statements
• Determine the prognosis for congestive heart failure

The Veterinary Consultation

• Diagnostic tests for cardiac disease in animals may include:
  • Signalment of the animal
  • History taking
  • Physical examination
  • Thoracic radiography
  • Electrocardiography
  • Laboratory testing
  • Echocardiography
  • Cardiac catheterisation
  • Blood pressure measurement
  • Post-mortem examination

The Veterinary Consultation - Signalment

• Species: Hypertrophic cardiomyopathy is more common in cats, while dilated cardiomyopathy is more common in dogs
• Breed: Acquired valvular endocardiosis is more prevalent in smaller breeds and idiopathic dilated cardiomyopathy is more common in larger breeds
• Age: Young animals are more likely to have congenital defects
• Sex: Some diseases, such as patent ductus arteriosus, are more common in females, while others, like hypertrophic cardiomyopathy, are more common in males

History Taking

• Start with general history and use communication skills
• Listen carefully to owner concerns, using both open and closed questions
• Negative findings are as important as positive ones
• Use clinical and medical knowledge to categorize data into clinically relevant information
• Move to specific questions focused on the cardiovascular system
• Focus on vaccination, preventative healthcare (e.g., heartworm, deworming) and WH questions (when, what, how, who, where) in the history taking process.

History Taking for Cardiac Cases

• Look for changes in:
  • Attitude, behaviour, and activity level (e.g., exercise intolerance, depression, fatigue)
  • Breathing (e.g., labored breathing, increased resting respiratory rate)
  • Appetite and weight
  • Coughing (e.g., acute cough, intermittent cough)
  • Sleeping habits (e.g., restlessness at night)
  • Previous evidence of heart disease (e.g., heart murmurs, radiographic changes, enlarged heart)
• Assess exercise tolerance (vigorous, free exercise, etc)
• Assess syncope (transient loss of consciousness)
• Assess breathlessness (details of coughing)
  • Sound? Timing? Occurring with changes?
• Appetite, body condition, weight loss: abdominal enlargement could be a first sign
• Negative answers are equally pertinent to positive answers

Physical Exam for Cardiac Cases

• Be thorough in auscultation
• Use a quality stethoscope
• Conduct the examination in a quiet, cool room minimizing noise and excitement
• Position animal for auscultation, avoiding factors such as purring and panting

Physical Exam for Cardiac Cases - Arterial Pulse

• Assess femoral pulse: strength, regularity, and rate (e.g., hypokinetic vs hyperkinetic)
• Compare left and right
• Strength, rate (normal, irregular, fast, slow)
• Compare to heart rate

The Physical Exam for Cardiac Cases - Palpating the Precordium

• Palpate intercostal spaces 5th and 6th
• Assess strength, weakness, and thrills

Physical Exam for Cardiac Cases - Chest Wall and Thoracic Percussion

• Chest wall compressibility
• Resonant sound, hollow

Physical Exam for Cardiac Cases - Abdomen and Ballottement

• Assess for fluid wave, organomegally

Thoracic Auscultation

• Evaluate heart rate and rhythm
• Mitral valve best heard in the left 5th intercostal space close to the sternum
• Aortic valve best heard in the left 4th intercostal space close to the sternum
• Pulmonic valve best heard in the left 3rd intercostal space close to the sternum
• Tricuspid valve best heard in the right 3rd or 4th intercostal space close to the sternum
• Evaluate cardiac sounds (S1, S2, S3, S4) and murmurs.

Cardiac Murmurs - Grade

• Grade I: very soft murmur
• Grade II: soft murmur (quiet than S1 and S2)
• Grade III: moderate murmur (as loud as S1 and S2)
• Grade IV: louder than S1 and S2, but no palpable thrill
• Grade V: very loud murmur with palpable thrill
• Grade VI: very loud murmur with palpable thrill, still audible when the stethoscope is removed from the chest

Is it an Innocent Murmur?

• Intensity of the murmur doesn't always correlate with severity, thus serial examination is crucial
• Young animals (pups and kittens) - murmurs could be innocent (low grade, typically systolic, louder when heart rate increase)
• Typically disappear by 4-5 months of age

Diagnostic Approach - Radiography

• Chest X-rays (dorsal ventral and lateral views)
  • Evaluate extra-thoracic structures, pleural space, pulmonary parenchyma, cardiac silhouette, shape, size, and vessels
• Vertebral Heart Score (VHS): 8.5-10.5 for dogs and 7.5 for cats (note breed variations)

Diagnostic Approach - Echocardiography

• Assess heart function (size, shape, volume, performance)
• Use transthoracic imaging (parasternal windows)
• Right and left thoracic sides (intercostal spaces), sternum to costochondral junctions
  • Provide Two-dimensional, M-mode, Colour Doppler, and Spectral Doppler images
  • Provides a critical view of the heart

Diagnostic Approach - ECG

• Assess cardiac rhythm disturbances
• Evaluate chamber enlargement (atrial premature complexes)
• Look for atrial fibrillation (commonly in dogs and cats)
• Check for ventricular tachyarrhythmias
• May help detect conditions like heart failure

Diagnostic Approach - Haematology and Blood Biomarkers

• Establish minimum database profile
• Identify abnormalities (anaemia, immune-mediated conditions, inflammatory/infectious disease)
• Assess other organ function (liver, kidney, etc)
• Note protein, albumin, and globulin
• Natriuretic peptides (e.g. NT-proBNP/NT-proANP) indicative of cardiac status.
• BNP/ANP (Natriuretic peptides): used for ventricular dilation
• Cardiac troponin: for myocarditis

Prognosis

• Companion animals: average survival time 1-2 years
• Recurrent signs can lead to rapid progression
• Prognosis for horses is poor once overt heart failure is diagnosed
• Euthanasia may be the treatment option

Treatment Plan

• Regulate haemodynamic status with monitoring and pharmacological optimization (preload, afterload heart rate, contractility)
• Use vasodilatory therapy, ACE inhibitions, diuretics, and positive inotropes
• Use beta blockers, dietary modifications, and lifestyle changes

Treatment examples (Diuretics)

• Furosemide (0.5-4 mg/kg PO, IV or q8-12h); CRI (0.3-0.5 mg/kg/h)
• Spironolactone (0.5-2 mg/kg PO q12-24h)
• Hydrochlorothiazide (0.5-1 mg/kg PO q12-24h)