Systolic Dysfunction Flashcards
Rule #1 of the heart
- Know normal circulation and oxygenated vs deoxygenated blood
Rule #2 of the heart
- Heart is a muscle
- Heart will hypertrophy if it has to work harder
Rule #3 of the heart: What are the three main functions?
- ) Conduct electricity
- ) Systole (contract)
- ) Diastole (dilate)
Rule #4 of the heart about blood flow
- Water is LAZY!
- Flows from high to low pressure
Systemic venous pressure value
- 5 mmHg
Right atrial pressure
- 5 mm Hg
Right ventricular pressure
- 5 mmHg in diastole
- 20 mmHg in systole
Pulmonary artery pressure
- 8 mmHg in diastole
- 20 mmHg in systole
Pulmonary circulation pressure
- 6 mmHg
Pulmonary vein pressure
- 6 mmHg
Left atrial pressure
- 6 mmhg
Left ventricular pressure
- 6 mmHg in diastole
120 mmHg in systole
Why is the left ventricle so high pressure during systole?
- Has to pump against gravity
Aortic pressure
- 80 mmHg diastole
- 120 mmHg systole
What is the calculation for Blood pressure? Cardiac output?
- BP = CO * Systemic vascular resistance
- Cardiac output = Stroke volume * heart rate
What three things impact stroke volume?
- Preload
- Afterload
- Contractility
What are the two morphologic responses to disease for the heart?
- Concentric hypertrophy
- Eccentric hypertrophy
What diseases lead to concentric hypertrophy?
- Diastolic dysfunction
- Pressure overload
What diseases lead to eccentric hypertrophy?
- Systolic dysfunction
- Volume overload
What diseases in the heart do not usually lead to hypertrophy?
- Arrhythmias
What happens during concentric hypertrophy?
- Heart muscle becomes too thick
- Lumen is smaller, and walls get thicker
What happens during eccentric hypertrophy?
- Walls stay the same, but the lumen gets bigger
- Systolic dysfunction occurs first, and then you get eccentric hypertrophy secondary to that
Systolic dysfunction and volume overload
- Not as much blood leaving the heart
- Next time you go into diastole, it’s filled more already
- Volume overload secondary to systolic dysfunction
What is point of maximal intensity of systolic dysfunction murmur?
- on left side below costochondral junction (mitral valve)
- Left apical murmur
What is timing of systolic dysfunction murmur?
- Systole
What is quality of systolic dysfunction murmur?
- Regurgitant
Femoral pulses for systolic dysfunction quality
- Potentially weak
- May have pulse deficits too if arrhythmias
Primary causes of systolic dysfunction
- Dilated cardiomyopathy
2. Arrhythmogenic Right Ventricular Cardiomyopathy
Secondary causes of systolic dysfunction
- Toxin/drug
- Dietary deficiency
- Tachycardia-induced cardiomyopathy
- Hypothyroidism
- Inflammation
What non-infectious diseases can lead to myocarditis and secondary systolic dysfunction?
- Trauma (HBC)
- Heat stroke
- Systemic inflammatory disorders (septicemia, immune-mediated diseases)
What infectious diseases can lead to myocarditis and secondary systolic dysfunction?
- Viral (Parvo, distemper)
- Bacterial (Bartonella, Borrelia)
- Protozoal (Trypanosoma or Chagas; Toxoplasma)
Treatment for myocarditis and secondary systolic dysfunction secondary to systemic inflammation?
- Treat underlying disease
Prognosis for myocarditis and secondary systolic dysfunction secondary to systemic inflammation?
- Depends on underlying disease
- Heat stroke is okay if you don’t have MODS
How can hypothyroidism lead to systolic dysfunction?
- Dysfunction of Hypothalamic-pituitary-thyroid axis (see notes)
- Decreased production of T4 and T3
Etiology of hypothyroidism
- Thyroiditis
- Idiopathic atrophy
- Bilateral neoplasia
Indirect effects of thyroid hormones on the heart
- Increase metabolic rate
- Think about what hypothyroidism would do
Direct effects of thyroid hormones on the heart
- Inotropy and + chronotropy
- Think about what hypothyroidism
Ultimate impact of hypothyroidism on the heart due to direct and indirect effects
- Decreased contractility and decreased heart rate
Treatment for hypothyroid induced systolic dysfunction
- Treat the hypothyroidism
- Levothyroxine
Prognosis for hypothyroid induced systolic dysfunction
- Good with treatment
- RARELY a cause of myocardial failure
Treatment for tachycardia-induced cardiomyopathy and systolic dysfunction
- Stop the tachycardia
- Anti-arrhythmic medications: Digoxin, Diltiazem, Beta-blockers, Sotalol
Prognosis for tachycardia-induced cardiomyopathy and systolic dysfunction
- Guarded to good
- Potentially curable
Function of taurine
- Amino acid
- Diverse function
- Concentrates in the heart and retina
- Essential amino acid in cats!!!
What impact can taurine deficiency have on an animal?
- Central retinal degeneration
- Cardiac systole dysfunction
Who gets taurine deficiency systolic dysfunction?
- Cats
- American Cocker Spaniels
- MAY be a link with grain free and high legume diets
Diagnosing systolic dysfunction secondary to taurine deficiency
- Diet history
- Taurine blood levels
Treatment for systolic dysfunction secondary to taurine deficiency
- Treat CHF: Furosemide, pimobendan, ACE inhibitor
- Taurine supplementation
Prognosis for systolic dysfunction secondary to taurine deficiency
- Guarded to good
- Potentially curable
L-carnitine role
- Fatty acid metabolism and energy production
- Concentrated in skeletal and cardiac muscles
What happens with L-carnitine deficiency potentially?
- Cardiac systolic dysfunction
Who gets L-carnitine deficiency?
- American Cocker Spaniels
- Golden Retrievers
- Boxers
Diagnosis of systolic dysfunction secondary to L-carnitine deficiency?
- Diet history
- Myocardial levels (myocardial biopsy)
- Response to supplementation
Treatment for systolic dysfunction secondary to L-carnitine deficiency?
- Treat CHF: Furosemide, pimobendan, ACE-inhibitor
- L-carnitine supplementation
Prognosis for systolic dysfunction secondary to L-carnitine deficiency?
- Guarded to good
- May be curable
What nutritional deficiency can lead to systolic dysfunction in large animals or food animals?
- Selenium and Vitamin E
What is Vitamin E/Selenium deficiency called in horses/cows vs pigs?
- White muscle disease
Which drug is most commonly implicated for causing systolic dysfunction?
- Doxorubicin (Adriamycin)
- Chemotherapeutic agent
Doxorubicin cardiotoxicity
- Dose dependent (will happen with a higher dose)
- Arrhythmias
- Severe systolic dysfunction
Treatment for doxorubicin induced systolic dysfunction
- No direct treatment
Prognosis for for doxorubicin induced systolic dysfunction
- Poor
- Severe systolic dysfunction is irreversible
Primary dilated cardiomyopathy how to diagnose?
- Diagnosis of exclusion
- Rule out toxin/drug, dietary deficiency, tachycardia, hypothyroidism, and inflammation
Etiology of primary DCM
- Idiopathic
- Suspected genetic disorder
Who gets DCM: Age?
- Adults
Who gets DCM: Breed?
- Two-handed dogs!
- Irish Wolfhounds, Great Danes, Boxers
- American Cocker Spaniels
- Dobermans!
Treatment for Stage B1 (mild) DCM
- No treatment
- Monitor
Treatment for Stage B2 (moderate/severe) DCM
- Pimobendan
- +/- ACE Inhibitor
Treatment for Stage C (post-CHF) DCM
- Furosemide
- Pimobendan
- ACE inhibitor
- +/- Spironolactone
- +/- Anti-arrhythmics
What happens to blood flow with DCM?
- Not enough blood going forward (systolic dysfunction)
- Most often a disease of the left side of the heart
- Blood will go back to the lungs (left sided CHF)
Prognosis for B1 DCM
- Year to never
- Can take a VERY long time to get to stage C
Prognosis for B2 DCM
- Months to year to never depending on age at diagnosis
Prognosis for Stage C DCM Dobermans
- 3-6 months
- Less with atrial fibrillation
Prognosis for Stage C DCM Breeds besides Dobermans
- 6-12 months
Monitoring for DCM
- Ideally monitor with echocardiogram
- Ideally at least yearly, possibly more if very severe (up to 6 months)
Arrhythmogenic right ventricular cardiomyopathy breed
- Boxers
Arrhythmogenic right ventricular cardiomyopathy - which side of the heart is most often impacted?
- Right sided disease
Arrhythmogenic right ventricular cardiomyopathy - features of dsisease
- Arrhythmias (most often ventricular)
- Syncope and/or sudden death
Etiology of Arrhythmogenic right ventricular cardiomyopathy
- Idiopathic, suspect genetic
Histologic characterization of Arrhythmogenic right ventricular cardiomyopathy
- Fibro-fatty replacement of myocytes
Pathophysiologic effects of Arrhythmogenic right ventricular cardiomyopathy
- Systolic and diastolic dysfunction
- Cannot conduct electricity as well
- Likely due to fat replacement of myoctes
Diagnosis of Arrhythmogenic right ventricular cardiomyopathy
- Holter monitor
- Echocardiogram
Normal amount of VPCs in 24 hours for regular dogs and Boxer dogs
- <50 VPCs in 24 hours
- Boxer should have <100 VPCs
Treatment for Arrhythmogenic right ventricular cardiomyopathy if just arrhythmias
- Mexiletine
- Sotalol
Arrhythmogenic right ventricular cardiomyopathy Treatment if just CHF/Systolic dysfunction
- Furosemide
- Pimobendan
- ACE inhibitor
- +/- Spironolactone
Arrhythmogenic right ventricular cardiomyopathy Treatment if CHF and arrhythmias
- Mexiletine
- Sotalol
- Furosemide
- Pimobendan
- ACE inhibitor
- +/- spironolactone
Prognosis for Arrhythmogenic right ventricular cardiomyopathy if just arrhythmias
- Guarded
- Syncope and sudden death
Prognosis for Arrhythmogenic right ventricular cardiomyopathy if systolic dysfunction and CHF
- Guarded
- 3-6 months
- Often will get ascites
