General Principles Flashcards
What does cardiac coughing occur?
At night - compression of the corina
When does respiratory coughing occur?
During exercise / excitement
What do you want to ask about in a cardiac specific history?
Coughs Dysnpnoea Tachypnoea Exercise tolerance Syncope Mm colour Resting respiratory rate
What is the normal respiratory rate for a dog?
20-30
How should you categories dysponea?
Inspiratory / expiratory
Restrictive - LRT
Or obstructive - URT
What should you check on a cardiac exam?
CO
Pulse quality, mm colour, CRT, warmth of extremities
Assess for signs of heart failure Forward: - reduced pulses - slow CRT and pale mm - cold extremities
Left sided congestive:
- pulmonary crackles
- cough
- restrictive inspiratory and expiratory breathing pattern
Right sided congestive:
- positive hepatojugular reflex
- ascites
- subcut oedema and muscle wastage
- hepatomegaly
Cardiac auscultation Respiratory auscultation Palpate the larynx and trachea Thoracic percussion Thoracic compressibility - more useful in cats
What are eye clinical signs of forward heart failure?
= signs of poor cardiac output Lethargy and exercise intolerance Weak femoral pulse Unable to detect distal pulses Pale MM and slow CRT Cold extremities Hypothermia Cardiogenic shock
How should you treat forward heart failure?
DO NOT GIVE FLUIDS
Give positive inotropes
What are the signs of right sided congestive heart failure?
Ascites Distended jugular veins Positive hepatojugular reflex Pleural effusion Subcutaneous oedema Muscle wasting
What are the signs of left sided congestive heart failure?
Tachypnoea
Inspiratory and expiratory restrictive breathing pattern
Cough due to left atrial enlargement
Soft respiratory crackles on auscultation
What is the normal heart rate in dogs?
70-160
What is the normal heart rate in cats?
160-240
How should you describe a heart murmur?
PMI - left or right, base or apex
Timing - systolic, diastolic, continuous
Character - plateau, descrescendo, crescendo descrescendo, brief mid systolic, blowing
Radiation
Grade - I - VI
How do you grade heart murmurs?
I - very quiet murmur
II - murmur quieter than the heart sounds
III - murmur as loud as the hear sounds
IV - murmur louder than the heart sounds
V - louder the heart sounds and you can palpate precordial thrill
VI - louder than the heart sounds, precordial thrill, can heart murmur with the stethoscope lifted off the chest wall slightly
What is a diastolic gallop?
S3 and S4 heart sounds that are not normally audible in small animals
How can you auscultate diastolic gallops?
Using the bell of the stethoscope
Applying very little pressure over the left apex
What are normal lung sounds called?
Bronchovesicular lung sounds - harsher when there is an increased respiratory rate
Describe some adventitious lung sounds.
= abnormal lung sounds
Crackles - inspiratory - smaller airways opening
Wheezes - expiratory - due to narrowed airways - pulmonary fibrosis
What does dull thoracic percussion suggest?
Pleural effusion
What does resonance on thoracic percussion suggest?
Pneumothorax
What can reduced thoracic compressibility in a cat mean?
Cranial mediastinal mass
What is preload?
Venous return to the heart
Determines the end diastolic stretch on the atrial cardiomyocytes before contraction
What is afterload?
The resistance to ventricular ejection during systole
What are the major consequences of congestive heart failure?
Oedema and effusions Peripheral vasoconstriction Tachycardia Arrhythmias Remodelling Fibrosis of the myocardium
What are the pathophysiological events that occur in response to a reduced CO in heart failure?
Vasoconstriction
Increased heart rate
Myocardial remodelling and fibrosis via RAAs
Na+ and water retention via aldosterone - oedema and effusion
What adrenoreceptor as are involved in the baro-reflex?
Beta 1 adrenoreceptors
What cardiac decompensation does increasing the heart rate via the baroreflex cause?
Increases myocardial oxygen consumption
Reduces coronary perfusion
What cardiac decompensation does vasconstriction via the baroreflex cause?
Increases blood pressure
What does sympathetic stimulation of the beta 2 adrenoreceptors in the kidney cause?
Renin secretion
What is the effect of angiotensin II on the body
Potent vasoconstrictor Myocardial hypertrophy and fibrosis Causes ADH release Increases GFR Increases sympathetic activity Stimulates aldosterone release
= attempts to increase preload by increasing venous return
What substances in the body naturally counter-act the RAAs system?
Atrial natriuretic peptide - released following atrial stretch
Brain natriuretic peptide - released following ventricular stretch
- antagonise the RAAs - vasodilation, cause diuresis and sodium excretion
What clinical pathology tests are available for heart failure?
Pro-BNP - longer half life than normal BNP - can be assayed
Endothelin - possibly a future assay
What are the major pathological consequences of congestive heart failure?
Oedema and effusions
Peripheral vasconstriction
Tachycardia / arrhythmias
Remodelling and fibrosis of the myocardium
What are the mediators of vasoconstriction?
Noradrenaline
Angiotensin II
Reduced bradykinin levels vasopressin
Endothelin
What mediators stimulate cardiac remodelling?
Angiotensin II
Aldosterone
Endothelin
Catecholamines
What kind of hypertrophy does volume overload cause?
Eccentric hypertrophy = chamber dilation
What kind of hypertrophy does pressure overload cause?
Concentric hypertrophy - wall thickened
What cardiac diseases cause eccentric hypertrophy?
Mitral valve regurgitation Ventricular septal defects Patent ductus arteriosus Tricuspid regurgitation Anaemia Exercise
What cardiac disease cause concentric hypertrophy?
Aortic stenosis Systemic hypertension Pulmonic stenosis Pulmonary hypertension Exercise
Define maladaptive remodelling.
Changes in relative wall thickness + altered geometry of the heart chamber
Why do tachycardia and arrhythmias occur during heart failure?
Elevated catecholamine levels
Increased sympathetic drive
Reduced vagal tone
Myocardial fibrosis and ischaemia due to remodelling
