Clinical Presentation & Diagnostic Considerations of the Small Animal Cardiac Patient

Describe the normal cardiac auscultation.

• Sounds

• ECG

• S₁: Mitral and tricuspid valves closure (AV valves)

• Beginning of systole

• Is longer, louder, lower pitched

• S₂: Aortic and pulmonic valves closure.

→ Lub(S₁) - dup (S₂)

• Is shorter, not as loud

• Beginning of diastole

S₄ & S₃ - usually not heard in small animal patients

• Atrial depolarization = S₄

• Then Isovolumetric contraction - pressure in left and right ventricles rises

• Until aortic valve opens (Systole)

• Pressure falls, aortic and pulmonic valve close or blood would reenter the ventricle

• Isovolumetric relaxation

What are the main qualities of a heart murmur?

Timing

Intensity

Location

Quality

Pitch

**First three to important to recognize

Describe the features of the timing in regard to a heart murmur.

• Determined by the phase of the cardiac cycle, when did it occur?

• Systolic (If produced from S₁ to S₂)

• S1 - beginning of systole

• Diastolic (S₂ to S₁)

• S2 - beginning of diastole

• Continuous (machinery)

• Hear it interrupted, throughout

• Early, Mid, Holo (through whole phase)

• More nuanced, can be difficult to hear with high HR

Describe the features of the intensity in regard to a heart murmur.

• How loud is the murmur?

• Classification of grade of intensity from I to VI

• Degree of disease correlated to intensity of the murmur

Describe the heart murmur scale - grades 1-6 and the definition for each.

• Definition 1 - Heart Sounds

• Definition 2 - Localization (How far are you from the source)

Describe the features of the location in regard to a heart murmur.

• Where is the loudest murmur present?

• Left: Apical (Mitral), Basal (Aortic and Pulmonic)-

• Right: Apical (Tricuspid)

PAM → Side Change → T

Describe the features of the pitch and quality in regard to a heart murmur.

Describe how it behaves

• Pitch describes the auscultator's perception of the frequency of the murmur: high / medium / low

• Quality describes the "shape" of the murmur:

• Regurgitant (also called plateau shaped or rectangular, A)

• Ejection (crescendo-decrescendo or diamond shaped, B)

• Blowing (decrescendo, C)

How can you diagnose an arrhythmia?

• What is a normal rhythm?

• Auscultation provides the first clue to the presence of an arrhythmia and in some cases the rhythm diagnosis.

• When an arrhythmia is auscultated or suspected, however, an ECG (Electrocardiogram) should always be obtained to confirm the diagnosis.

• Normal finding: Sinus rhythm

• Regular rhythm, characterized by a monotonous S1-S2 cadence.

• Approximately 60 - 160 bpm in dogs, 140 - 220 in cats.

What are normal arrhythmias?

• Normal finding: Sinus arrhythmia

• Regularly irregular pattern, associated with breathing.

• Normal or slow heart rate.

• Vagal Tone (VTo) induced:

• Inspiratory → Vto decreases, HR faster.

• In healthy, relaxed dogs, means heart is saving energy

• Cats = May be a sign of disease with increased vagal tone

• Since are usually stressed at the vet

What are some abnormal arrhythmias?

• Atrial fibrillation:

• Generally rapid, irregularly irregular rhythm.

• Variable loudness of heart sounds.

• ECG - random appearance of peaks

What are the features of normal respiratory sounds?

• Normal lung sounds are created by the turbulent movement of air in the tracheobronchial tree in large (> 2 mm diameter) airways → Transmission to the chest.

• «Bronchovesicular» and «vesicular breath sounds» implies «made in the alveoli» but are transmitted from the large airways.

• Inspiratory: Lobar and large subsegmental bronchi.

• Exhalation: Trachea and the first one to two divisions of bronchi.

Why do abnormal lung sounds occur?

• Disease state → Altered sound transmission →

• Efficient high-frequency sound transmission.

• Pleural disease/Pneumothorax → increased reflection of sound

• Reduced intensity of lung sounds.

• Not allowing sound waves to reverberate as they should.

What produces adventitious lung sounds?

• Abnormal lung sounds that are superimposed on normal (or increased/decreased) lung sounds.

• Three categories:

• Crackles

  • Fine

  • Coarse

• Wheezes

• Ronchi

What do “fine crackles” sound like upon auscultation?

• Common causes?

• High pitch (>800 Hz)

• Quickly muffled, unmusical lung sounds.

• Usually at the beginning/end of breathing.

Findings, not specific for disease, high overlap:

• Bronchitis

• Lung oedema

• Pneumonia

• Lung fibrosis

Fine Crackles

• Brief, popping and high pitched, similar to wood burning in a fireplace

• Heard in both phases, sometimes heard more in one phase than another

What do “course crackles” sound like upon auscultation?

• Usually lower pitch (≥700-800 Hz) and longer duration (<50 msec) than fine crackles.

• You can hear them over the trachea/mouth with/without stethoscopes.

These indicate the presence of fluid in the large airways!

• Bubbling sound quality, popping, low-pitched, longer and louder, heard in both phases

What do “wheezes” sound like upon auscultation?

• Longer duration (>80-100 msec), relatively high frequency (oft >1000 Hz) compared to crackles.

• Sinusoidal (musical), narrowing of airway, caused by vibration of small bronchial walls.

What do “ronchus/ronchi” sound like upon auscultation?

• Longer duration(>100 ms), but in contrast to Wheezes they have deeper frequency (<2-300 Hz).

• Vibration of large airways or air- fluid interface disruption.

• Snoring sound.

Describe the sounds characteristic of stridor.

• Harsh high-pitched sound produced by obstruction of upper airways:

• Nasal stridor

• Pharyngeal stridor

• Laryngeal stridor

• Tracheal stridor

Describe the sounds characteristic of stertor?

• Low pitch nasopharyngeal obstruction.

• Brachycephalic syndrome!

Describe how the pulse is evaluated.

• Pulse Pressure: Difference between systolic and diastolic pressure

  • Wide difference: Strong, hyperkinetic.

  • Small difference: Weak, hypokinetic (can be high or low)

• Anacrotic Pulse (parvus et tardus): weak and delayed.

• Pulsus alternans: Strong/Weak alternation.

• Pulsus paradoxus: Weak arterial pulse during inspiration, strong during expiration.

• Sometimes with pericardial effusion or tamponade

• Pulsus bigeminus: Regular alteration of ventricular contractionised by premature

• Additional beat or pulse wave

What does the hepatojugular reflex tell you?

Hepatojugular Reflex: cranial part of abdomen squeezed, enters right side, jugular vein becomes enlarged

• Right heart failure: Increase RA → Hydrostatic Pressure Caval Veins

→ Backwards Failure

• Pressure on the liver → rise in venous pressure.

• May also see ascites - intravascular hydrostatic pressure increases, fluid leaks out

What does CRT evaluation allow you to assess?

• Capillary Refill Time (CRT) parameter to evaluate peripheral perfusion. Normal is below two seconds.

• Cyanosis: bluish discoloration of the mucous membranes

• Central: systemic deoxygenation of arterial blood, not from lungs

• Peripheral: localized reduction in oxygenated haemoglobin.

• Differential: deoxygenation of caudal part of body, with normal oxygenation of head and forelimbs, certain region of body

What is a cough and how relevant is it in cardiac disease?

• Sudden expiratory effort in which a loud expulsion of air occurs.

• Defensive Mechanism (Stimulus: Irritation).

• Larynx, Trachea, Bronchi, Mediastinum.

• Cardiac disease? NOT in cats!

• Can produce a cough in dogs, receptors in upper areas or larynx and, trachea and large bronchi

• Pulomary oedema in alveoli should not trigger coughing reflex, unless it reaches bronchi

• Haemoptysis: Bloody Cough.

What are some potential differentials for coughs?

Describe the main features of respiratory distress?

• Eupnoea: normal, unlaboured breathing.

• Hyperpnea (more volume) / Tachypnoea (higher frequency)

• Dyspnoea: respiratory difficult

• Paradoxical breathing: Breathing pattern in which the chest moves in on inhalation and out on exhalation.

Lung depend on _____ and _____.

Ventilation, Circulation

V & Q

What are differential diagnosis for dyspnoea?

What is syncope?

• Defined as transient loss of consciousness (TLOC) due to cerebral hypoperfusion, characterized by a rapid onset, short duration, and spontaneous complete recovery.

• Presyncope (near-syncope): used to indicate symptoms and signs that occur before unconsciousness in syncope.

• Prodrome of syncope

• Not followed by loss of consciousness

How can you distinguish a seizure form a syncope event?