Cardiology Flashcards
Selenium toxicity - how does it happen in Sm Rum?
- Often if give the wrong form (different concentration)
Manifestations of CV Disease
- Edema, pleural effusion, ascites
- Arrhythmias
- Murmurs
- Muffled Heart Sounds
- Exercise Intolerance, Weakness, SYncope
- venous distension/pulsations
- Painful peripheral swelling
- Lymphadenopathy
Main causes of edema?
- Increased vascular permeability
- Increased capillary hydrostatic pressure
- Decreased vascular oncotic pressure
- Increased tissue oncotic pressure
- Lymphedema
What can cause increased vascular permeability?
- Endotoxin
- Trauma
- Infection
- vasculitis
- Mechanisms are cytotoxins and oxygen radicals, leukotrienes, H2O2, etc.
Clinical signs of increased vascular permeability
- petechiation and ecchymoses
Where to look for signs of sepsis like petechiation and ecchymoses?
- Nares, pinna, vulva
What causes increased capillary hydrostatic pressure?
- CHF (e.g. Se deficiency with cardiomyopathy)
- Tricuspid valve insufficiency
- venous thrombosis
- Liver disease (portal vs obstruction)
- Etc.
Total protein value and albumin value for edema attributable to decreased vascular oncotic pressure?
- <5 g/dL for TP
- <1.5 g/dL for albumin
Causes of decreased vascular oncotic pressure?
- Don’t make it! (starvation, liver disease)
- Lose it (renal, GIT, 3rd space)
- You screwed up (hemodilution)
Causes of edema from increased tissue oncotic pressure?
- Infection
- Topical counterirritants
- Not generally a big deal
What causes lymphedema due to blocked lymphatics?
- Tumors
- Trauma
- increased CVP
How do you diagnose edema?
- Press into it to see if it pits
Other causes of swelling to consider
- Hydrops
- Prepubic tendon rupture
- Fat
Benign arrhythmias
- SInus arrhythmia
- Sinus bradycardia
What usually causes sinus bradycardia in ruminants?
- Lack of feed intake
Pathologic arrhythmias
- Atrial fibrillation, premature depolarization
What usually causes atrial fibrillation?
- GIT disease
- Electrolyte or Acid/Base Disturbances
Atrial standstill
- No P waves
What causes Atrial standstill most commonly in Ruminants?
- Mostly metabolic acidosis, which influences potassium
- Hydrogen crosses across the cell membrane into the cell cytoplasm
- To maintain electroneutrality, if a cation goes in, either a cation hsa to go out or an anion has to come in
- Potassium leaves the cell in exchange for hydrogen ions going into the cell
- Results in increased extracellular potassium
What happens to action potentials with hyperkalemia?
- Membrane is closer to threshold
- Stimulus that would normally be subthreshold can trigger an action potential
- Ultimately the sodium channels become refractory and go into standstill
What happens to action potentials with hypokalemia?
- Less likely to fire an action potential
Hyperkalemia and the heart
- Increased potassium = membrane depolarization
- Depolarization opens sodium channels, increases inactivation (slow depolarization = increased accommodation, no action potential)
- more depolarization –> decreased sodium channels, increased potassium channels
- Cells become refractory as they can’t hyperpolarize
- Results in atrial standstill, ventricular fibrillation, and asystole
Other causes of arrhythmias (less common)
- Electrolyte abnormalities
- Pericarditis
- Valvular disease
- Myocardial disease
- Toxemia
- Cor pulmonale
- Lymphosarcoma
- Fever
What causes murmurs?
- Turbulence! (vs laminar flow)
What is the Reynolds number and how does it relate to turbulence?
- Ratio of inertia:viscosity
- Velocity over viscosity
- When it’s >2000, turbulence occurs
- Increased velocity or decreased viscosity (e.g. anemia) predisposes to murmurs
What is the level of PCV at which murmurs of anemia are typically noted?
- PCV <25
How to characterize murmurs?
- Part of the cardiac cycle
- Intensity
- Shape/frequency
- PMI
- Radiation
Types of radiation
- Systolic, diastolic, and continuous
Systolic murmur
- Between 1st and 2nd sound
Diastolic murmur
- Between 2nd and 1st sounds
Murmur Grade 1
Soft, difficult to hear
Murmur grade 2
Soft, readily heard
Murmur Grade 3
Moderate
Murmur Grade 4
Loud with palpable thrill
Murmur Grade 5
Louder but still need stethoscope
Murmur Grade 6
- Audible with stethoscope not contacting skin surface (really loud)
Where is PMI for Pulmonic valve?
- Left sided heart base (3rd-4th ICS)
Where is PMI for aortic
valve?
- Left sided heart based, radiates
- 4th to 5th ICS
Where is PMI for mitral valve?
- Left, near elbow (apical)
- 5th or 6th ICS
Where is PMI for tricuspid valve?
- Right sided
- Between shoulder and elbow
- 3rd or 4th ICS
Ejection murmur
- Crescendo-decrescendo
Regurgitant murmur
- Same
Diastolic decrescendo murmur
- Decreases only
Dfdx for ejection murmurs?
- Innocent
- Anemia, fever
- Aortic or pulmonic stenosis
- ASD, VSD, Tetralogy
Regurgitant murmur dfdx
- Mitral regurgitation
- Tricuspid regurgitation
- VSD, Tetralogy
Which valve most commonly has regurgitation?
- Tricuspid valve
What are four categories of reasons for muffled heart sounds?
- Displacement
- Soft tissue mass
- Air
- Fat
Displacement causes
- Pericardial effusion
- Diaphragmatic hernia (rare)
Soft tissue mass causes
Abscess, tumor, GIT
Air muffling causes
- Pneumothorax, pneumomediastinum, emphysema
Fat muffling causes
- Just fat
What can cause exercise intolerance/weakness?
Many systems, including cardiovascular
Manifestations of exercise intolerance that might be measurable
- Failure to perform or produce
- Cough on exertion
- Respiratory distress
- Recumbency, reluctance to rise or move
Where is the normal jugular pulse?
- <1/3 of the neck with the head up
- Shouldn’t go above about 8cm above the base of the heart
- Remember if the head is below the neck, it can go further up
What contributes to the jugular pulse positivit?
- Atrial contraction
- Isovolumetric ventricular contraction
- Atrial filling
Root cause of venous distention and pulsations
- Increased resistance to right ventricular filling
Dfdx for distention and pulsations
- Right heart failure
- Constrictive pericarditis
- Cardiomyopathy
Dfdx for prominent pulsations
- Tricuspid regurgitation
- Arrhythmias associated with atrial contraction against a closed AV valve
Causes of congenital CV diseases
- Most not established
- Hereditary in some
- May happen with other congenital problems
When do you suspect congenital CV disease?
- Young animals
- Holodiastolic or continuous murmur (+/- thrill)
- Wide radiation
- Lethargic, weakness, failure to thrive
- Cyanosis
What is the most commonly reported congenital disease?
- Ventricular septal defect
- Can be alone or associated with something else
Cause of VSD
- Unknown
- Maybe heritable in some breeds
Where is the VSD in bovines compared to in camelids?
- Bovine: Usually in the membranous septum, ventral to the tricuspid
- In camelids, often towards the apex
CLinical signs of VSD
Variable!
Depends on:
- Size
- Shunt direction
- Concurrent problems (valve or myocardium)
Normal clinical signs of VSD
- Poor growth, dyspnea, etc.
Murmur in VSD***
- Bilateral, harsh, plateau, continuous (holostystolic)***
- Usually louder on the side it’s going to
- PMI at right tricuspid area USUALLY but can be left pulmonic area
- Palpable thrill usually
What is Eisenmenger’s complex?
- Right heart resistance results in VSD Left to right shunt (pulmonary hypertension) and eventually becomes right to left shunt
What’s the main issue with a right to left shunt?
- Putting unoxygenated blood directly into the left ventricle
Normal physiology of ductus arteriosus after birth?
- Ductus arteriosus normally closes due to decreased pulmonary vascular resistance and increased systemic vascular resistance
How long after birth is a PDA normal in calves? foals?
- Abnormal after birth in calves at any time
- UP to 96 hours in foals
What can cause variability in clinical signs of a PDA?
- SIze
- Direction of shunt
- Concurrent defects
Murmur in PDA
- Continuous, high pitched, MACHINERY murmur
- Loudest on left but audible on the right 3rd-4th ICS
- Can exist without a murmur (large ones)
Tetralogy of Fallot - what are the four parts?
- Overriding aorta
- VSD
- RV hypertrophy
- Obstruction of pulmonic arterial flow (stenosis)
What causes Tetralogy of Fallot?
- Abnormal development of conal septum in an embryo
Murmur in Tetralogy of allot
- pansystolic murmur with a thrill, left 3-4th ICS
What is the most common cause of cyanosis in extremely young animals with a murmur?
- Tetralogy of Fallot
How to rule out respiratory distress from Tetralogy of Fallot?
- TF has a murmur
How to rule out CNS disease from TF?
- TF has not other neuro manifestations
ASD - how common?
- Relatively common in calves
What is ASD often associated with?
- PDA
Signs of ASD
- Frequently asymptomatic
Shunt for ASD
- Left to right
Murmur in ASD
- Holosystolic ejection murmur at left heart base
- Shunt is usually left to right
What is the name when the heart is outside of the chest in the throat?
- Ectopia chorids cervicalis
Other congenital defects that are possible
- Pulmonic stenosis
- Tricuspid atresia
- Mitral chordae rupture
- Ventricular hypoplasia
- Truncus or pseudotruncus arteriosus
- Aortic anomalies
- Ectopia chordis cervicallis
Etiology of valvular diseases
- Degeneration, infection/inflammatory, trauma, or unknown (DIT in DAMNIT)
How do valvular diseases manifest in terms of murmur?
- Systolic, regurgitant murmur
- PMI over affected valve
How can infections result in valvular disease?
- Chronic active infections like footrot, abscesses, rumenitis, other septic processes) resulting in sustained bacteremia
Is preliminary valve damage necessary for valvular endocarditis?
- No
Most common bacteria in valvular endocarditis?
- T. pyogenes
- Strep species
- Most common
Which neoplasia can cause valvular disease?
- Primarily lymphosarcoma
Prognosis of valvular disease
- Depends on etiology, onset, duration, severity
- Generally guarded to poor
Treatment for bacterial endocarditis
- Long term cidal antimicrobials based on culture and sensitivity
- Aspirin
- Low dose heparin
- Furosemide
- Digoxin
How to diagnose bacterial endocarditis?
- Most often with blood culture
- Repeated blood culture is helpful
What is Cor pulmonale also known as?
- Brisket disease
- Pulmonary hypertension
- High mountain disease
Pathophysiology of cor pulmonale?
- Effect of lung dysfunction on the heart (SECONDARY form of heart disease)
- Pulmonary hypertension –> right ventricular hypertrophy –> right ventricular dilation –> right ventricular failure
How does high mountain or altitude disease lead to Cor pulmonale?
- Hypoxic vasoconstriction of pulmonary arterioles
- Worsened by locoweed Oxytropis, Astralagus)
Chronic pulmmonary disease and Cor pulmonale Pathophys
- Hypoxic vasoconstriction of pulmonary arterioles
- Bronchopneumonia
- Lungworm infestation
Clinical signs of right heart failure in cor pulmonale
- Edema of brisket, mandible, ventrum, limbs
- Jugular distension, pulsations
- Dyspnea, tachypnea
- Tachycardia
- Split S2 (aortic and pulmonic valve closure)
- Tricuspid or pulmonic insufficiency
Rule outs for cor pulmonale
- Endocarditis, tricuspid insufficiency, cardiomyopathy, cardiac neoplasia, pericarditis, pleuritis, pleural effusion, etc.
Who most commonly gets cor pulmonale?
- Cattle
- Mostly calves
- May be a genetic predisposition
What elevation is most common for Cor pulmonale?
- > 6000 ft above sea level, but can manifest at a lower elevation if locoweed
Morbidity of cor pulmonale
0.5-2%
How does locoweed predispose to cor pulmonale?
- Toxic myocardial damage
Treatment for cor pulmonale
- Lower altitude*** (most important)
- Treat primary lung disease
- Diuretics
- DIgoxin
Prognosis for cor pulmonale
- Guarded once signs of RHF
Prevention of Cor pulmonale (IMPORTANT)
- Genetic selection (PAPs @ >5000 ft)
- Remove susceptible cattle
- Prevent locoweed ingestion
- Reduce incidence of pulmonary diseases (vaccinate for respiratory pathogens and mitigate via management)
What is PAP?
- Pulmonary arterial pressure testing
- They want to choose >5000 for cows that will be at high elevation
- Measure from right atrium to right ventricle to pulmonic artery
- If they don’t pass, don’t breed them
Causes of myocarditis
- Bacterial
- Viral
- Parasitic
Bacterial causes of myocarditis
- S. aureus, C. chauvoei, Mycobacterium spp.
Viral causes of myocarditis
- FMD
Parasitic causes of myocarditis
- Strongyles, Toxoplasma, Sarcocysts, Borrelia
Cardiomyopathy definition
- Subacute to chronic disease of ventricular myocardium without disease of valves, vessels or lungs
Causes of cardiomyopathy (4 main causes)
- Inherited
- Toxic
- Deficiencies
- Neoplasia
Cardiomyopathy - who is predisposed to inherit?
- Red Holsteins and Polled Herefords maybe
Toxins that can lead to cardiomyopathy
- Monensin
- Lasalocid
- Gossypol
- Phalaris
Vitamin/Mineral deficiencies or overdoses that can lead to cardiomyopathy
- Copper and selenium deficiency
- High molybdenum or sulfates
Which neoplasia can lead to a cardiomyopathy?
- Lymphoma
Clinical signs of cardiomyopathy and myocarditis
- variable - depends on extent and cause
- May be signs of a primary disease like mastitis or metritis
- Tachycardia, arrhythmias
- Signs of CHF
- Often go undiagnosed or masked by primary disease
Treatment of Myocarditis and cardiomyopathy
- Treat underlying cause or agent
- Control arrhythmias, CHF, shock
What is the name for Vitamin E and Selenium Deficiency?
- White muscle disease
Lesions in white muscle disease
- Fibrosis
- Mineralized foci in the heart
Selenium toxicity lesions
- More an acute inflammatory process without the mineralization
Pericarditis definition
- Inflammation or pericardium resulting in accumulation of fluid/exudate between visceral and parietal pericardium
Typical etiology pericarditis
- Trauma - “hardware disease”
- Hematogenous
- Extension from lungs or pleura
- Neoplasia
Clinical signs of pericarditis
- Nonspecific fever, anorexia, weight loss, lethargy
- Peripheral edema, jugular distension/pulses, tachypnea, dyspnea
- Ventral pain, abducted elbows, grunting, etc.
- Muffled heart sounds - absent lung sounds ventrally
- Pericardial friction rub- some thing washing machine murmur
Treatment for pericarditis
- Usually salvage procedure
- Poor prognosis
- Drainage
- 5th rib resection, pericardectomy
Prevention of pericarditis
- Magnets
- management to help with indiscriminate prehension
Necropsy findings of pericarditis
- Often fibrin covering the heart
How common are cardiac tumors?
- rare
Most common cardiac tumor?
- Lymphosarcoma
- Manifestation of BLV
- LEntivirus in cattle
Other cardiac tumors
- Mesothelioma
- Fibrosarcoma
- Adenosarcoma
- Carcinomas
Definition of atrial fibrillation
- Incoordinated atrial electrical activity
What is most common cause of atrial fibrillation in cattle?
- Acid/base and electrolyte disturbances secondary to GIT disease
- Hypocalcemia, hypokalemia, hypochloremia
- Metabolic alkalosis
Auscultation of atrial fibrillation
- irregularly irregular rhythm
ECG of atrial fibrillation
- Irregular R-R interval, No P waves (f waves), irregular QT intervals
Treatment for Atrial fibrillation in cattle?
- Treat underlying cause
- GIT disease
- Acid/base and electrolyte abnormalitiest
- Quinidine sulfate is DOC in cattle
- Electroconversion in small ruminants
