Pathology, Diagnostics and Therapeutics for Veterinary Cardiac Disease

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Pathology, Diagnostics and Therapeutics for Veterinary Cardiac Disease por Mind Map: Pathology, Diagnostics and Therapeutics for Veterinary Cardiac Disease

1. Pathophysiology

1.1. Pump failure - inadequate stroke volume and fall in cardiac output

1.1.1. Dilated cardiomyopathy Coronary vascular diseae

1.2. Volume overload - increased output, overwork, eventual failure

1.2.1. Valvular insufficiencies (mitral, aortic) Shunting disease (ventricular septal defect, patent ductus arteriosus) Chronic anaemia Eccentric Hypertrophy - inc lumen size, wall thickness same

1.3. Pressure overload

1.3.1. Hypertension (systemic, pulmonary) Narrow outflow tract (pulmonic stenosis, aortic stenosis) Concentric Hypertrophy - inc wall thickening (greater resistance) Hypertrophy - inc myocardial oxygen demand, fibrosis and hypoxia

1.4. Arrythmias

1.4.1. CO = HR x SV

1.5. Diastolic failure

1.5.1. Hypertrophic cardiomyopathy Dilated cardiomyopathy (myocardial fibrosis) Pericardial effusion

1.6. Body system equilibrium - maintained via homeostatic systems

1.6.1. Increased volume RAAS (Ang II, Aldosterone) ADH (osmoregulation) Renal autoregulation of flow (dec. renal flow, inc. sodium retention Inc. circulating volume, inc preload, inc. CO (Starling), inc systemic vascular resistance RAAS - may lead to excessive fluid retention, excessive resistance to ventricular emptying, effects on myocardium (chronically) ADH - retention of free water without sodium - hyponatraemia long term

1.6.2. Decreased volume Natriuretic peptides (heart muscles, urinate sodium) Renal autoregulation (inc renal flow, dec. sodium retention)

1.6.3. Autonomic effects Drop in CO, drop in arterial blood pressure (arterial underfilling) - baroreceptors, dec. parasympathetic activity, inc. sympathetic activity Norepinephrine - alpha and beta receptors Positive chronotrope = inc HR Positive Inotrope = inc cardiac contraction force Positive Luisitrope = improved cardiac relaxation

1.7. Heart failure

1.7.1. Tachycardia (symp tone) Poor peripheral perfusion (vasoconstriction) Fluid retention (RAAS, ADH) LCHF (elevated filling pressures on LHS, reteined fluid in pulmonary circulation) RCHF (retained fluid in systemic veins)

1.8. Vascular disease

1.8.1. Underperfusion Vascular obstruction, loss of function, ischaemia, ecrosis Thrombosis, embolism Increased hydrostatic pressures

1.8.2. Increased vascular permeability Oedema, haemorrhage Vasculitis

1.8.3. Abnormal flow and pressures Decreased oncotic pressure Hypoproteinaemia Decreased lymphatic drainage Lymphoedema

1.8.4. Degenerative, Inflammatory Vasculitis

1.8.5. Malformations Congenital and acquired

2. Physical exam

2.1. Pulse

2.1.1. Artery sites External maxillary Transverse facial Median Digital Coccygeal artery (cattle)

2.1.2. Match with auscultation? Pulse deficit? Regularity? Quality?

2.2. Auscultation

2.2.1. Left side Apex - Caudal, Mitral valve more audible (S1) Base - cranial, Pulmonic and Aortic valve (S2)

2.2.2. Right side Tricuspid valve, Maybe aortic valve, Ventricular septal defects

2.2.3. Heart sounds Lub = S1 Dup = S2 Lup Dup = Systole S2 to next S1 = Diastole S1 = Closure of AV valve, systole beginning S2 = closure of outflow valve, end of systole

2.2.4. Heart murmurs Left Heart base Pulmonic and aortic valves, ribspaces 3/4 Left Heart apex Mitral valve Right side Trcuspid, Ventricular septal defect loudest Type Systolic murmur Diastolic murmur Continuous murmur Crescendo-Decrescendo Grade 1 = barely audible 2 = clearly audible, does not radiate, quieter than S1/S2 3 = as loud as S1/S2, may radiate 4 = louder than S1/S2 5 = Precordial thrill palpable 6 = audiible with stethoscope off thorax Radiation Aortic murmur radiate up carotid arteries Mitral murmurs radiate dorsally

2.2.5. Gallop sound Diastole, S3/S4 audible, poor diastolic relacation

2.2.6. Lung sounds Crackles - pulmonary oedema Wheezes or stretorous inspiratory noise = resp disease

3. Echocardiography

3.1. Best for defining type of heart disease, not heart failure

3.1.1. M-mode Measure LV wall against time through systole and diastole

3.1.2. 2D Whole heart, heart lesions

3.1.3. Colour flow Doppler Blood towards transducer = red Away = blue Laminar flow = green

3.1.4. Spectral Doppler Time with ECG Velocity/time graph

3.1.5. Anatomy Right Right parasternal long axis = 4 chambers 5 chamber - can see PA Short axis papillary muscles - 90 degrees transverse towards tail Cut through aortic valve Short axis mitral valve - fish mouth view Short axis left atrium/aortic valve LA = comma, with L auricle Short axis pulmonary artery - cranially Left Apical 4 chambers, long axis

3.1.6. Chambers La:Ao diameter - see if LA enlarged Square shaped M-mode LV systolic function (% change in LV diamter, fractional shortening) High = hyperdynamic ventricle Low = hypokinetic, e.g. DCM

3.1.7. Blood direction, velocity, turbulence Valve stenosis, volume overload, shunts, endocarditis, pericardial effusion (echolucency)

4. Radiology

4.1. Heart failure

4.1.1. Right sided Hepatomegaly Peritoneal effusion Pleural effusoin

4.1.2. Left sided Pulmonary congestion Pulmonary oedema

4.2. Cats - oedema can affect any part of lung, and can be small part - common in cats Unusual to see pleural fluid in dogs

4.3. Cardiac size

4.3.1. Displacement of trachea

4.3.2. Shape of heart shadow, IC spaces, distance from diaphragm, vertebral heart score Can see eccentric hypertrophy, but not concentric hypertrophy

4.4. Angiography

4.4.1. Contrast medium into vessels, can see chambers

4.5. Chamber

4.5.1. Lateral Outward bend of cranial cardiac border - enlarged LA

4.5.2. Dorsoventral Left atrial bulge PDA - bump in aorta, dilation of PA, big LA, generalised cardiac enlargement

5. Therapeutic Principles

5.1. Preload

5.1.1. Venous reservoir Filling Tone (contracted state) Venous tone and fluid volume Diuretics - to remove fluid - too much persistent preload, full venous reservoir, congestive heart failure Venodilators - decrease preload, doesnt improve afterload - forward AND backward failure? Arteriodilators

5.2. Cardiac function

5.2.1. Inotropy Lusitropy Chronotropy (rate and rhythm) Systolic function Diastolic function Inotropes Diastolic function e.g. HCM cats

5.3. Afterload

5.3.1. Arterial circulation Output Tone Arterial tone Arteriodilators, easier to eject Too much hypotension?

5.4. Anti-arrythmic therapies

5.4.1. Controversial, no licensed agents

5.4.2. Restore adequate peripheral perfusion, control rate/rhythm, prevent sudden death Antidysrhythmic medication Ventricular arrythmias Supraventricular arrythmias Bradyarrythmias