Diastolic Dysfunction - Primary Flashcards
What is the impact of severe acute arteriolar vasoconstriction on heart rate?
- Increasing your systemic vascular resistance
- Heart rate should fall dramatically because your blood pressure is increasing
- reflex bradycardia, which is what happens with dexmedetomidine
Brain perfusion equation
- Systemic blood pressure - intracranial pressure
- If you have increased intracranial pressure, you will increase blood pressure to try and maintain the intracranial pressure
- If you have a dog with cerebral trauma and bradycardia, you can assume that your intracranial pressures are very high
- Cushing’s reflex
Etiology of HCM
- Genetic vs idiopathic
Breeds at risk for HCM
- Maine Coons
- Ragdolls
- Forest Cats
- Sphynxes
- Bengals and Birmans
Which species gets HCM?
- CATS
Genetic testing for HCM for Maine Coons and Ragdolls
- Myosin-binding protein C
Physical exam findings with HCM
- Systolic murmur MAYBE
- Gallop sound MAYBE
- MAY BE NORMAL
Diagnosis of HCM cats
- DIAGNOSIS OF EXCLUSION (like DCM)
- Echocardiogram
- Concentric hypertrophy of the LV
- Thickened left ventricular walls (free wall, septum, +/- asymmetric)
- Small LV chamber
- Thoracic rads to look for CHF
What should normal left ventricle wall thickness be?
- <5.5 mm
Which frame should you use to measure wall thickness?
- Diastolic
Causes of concentric hypertrophy to rule out?
Causes of systemic hypertension:
- Renal disease
- Hyperadrenocorticism
- Hyperthyroidism
- Diabetes mellitus
- Medications
- Acromegaly
- Pheochromocytoma
- Hyperaldosteronism?
Other causes of stenosis
- Pulmonic stenosis
- Aortic stenosis
If a young cat with a normal or low blood pressure, probably primary HCM
Treatment for Stage B1 HCM
- No treatment
- Monitoring
Treatment for Stage B2 HCM
- +/- ACE inhibitor
- +/- Beta blocker
- +/- Diltiazem
- +/- Spironolactone
- +/- Antithrombotic
Treatment for Stage C HCM with CHF
- Furosemide
- ACE inhibitor
- +/- Thoracocentesis
- +/- Pimobendan
- +/- Spironolactone
- +/- Antiarrhythmics
Treatment for Stage C HCM with arterial thromboembolism
- SUpportive Care
- Pain management
- Antithrombotics (aspirin, clopidogrel, Low molecular weight heparin)
Signs of left sided heart failure in cats
- Pulmonary edema
- Pleural effusion
What types of effusion can happen in cats with left sided CHF?
- Modified transudate
- chylous effusion
What are three differentials for chylous effusion in cats?
- Heart failure
- Neoplasia
- Idiopathic
Signs of right sided heart failure in cats
- Abdominal effusion
- Pleural effusion
- Pretty sure that right sided heart failure is unusual in general in cats
Pulmonary edema clinical signs
- Crackles
Pleural effusion clinical signs
- May not hear things ventrally or have dull lung sounds ventrally
Pulmonary edema treatment
- Furosemide and ACE inhibitor
- Diuretic gets rid of fluid
- ACE inhibitor to inhibit RAAS
Pleural effusion treatment
- Furosemide not good at getting rid of fluid, but will slow down re-accumulation
- Thoracentesis
Virchow’s Triad
- Endothelial damage
- Sluggish blood flow (Blood stasis)
- Hypercoagulability
- All of these can lead to thrombosis
Where does feline arterial thromboembolism usually occur?
- At the juncture of the aorta where the external iliac arteries split off
Clinical signs of feline arterial thromboembolism
- Paralyzed back legs
- No blood supply, so the legs are cold
- Femoral pulses weak or nonexistent
- Paw pads can become cyanotic (look at nail beds if paw pads are black)
Prognosis for stage B1 HCM
- fair to good
- May take year to progress
Prognosis for stage B2 HCM
- Guarded
- Will likely progress
Prognosis for Stage C with Heart failure
- Guarded (1-3 years with therapy)
Prognosis for Stage C with ATE
- Guarded to poor
Treatment for HCM studies
- No real studies
- We don’t know what works and c doesn’t
What is considered Stage C for HCM cats?
- Either HCM OR arterial thromboembolism
Critical period for post-ATE
- First 24-72 hours
- Concurrent CHF
What causes death in feline ATE?
- Reperfusion injury often due to hyperkalemia
- Potassium in the cell leaks out with necrosis from all of the cells that have died
- Once the clot breaks down and you re-establish blood flow, the potassium goes to the rest of the body
-
Sodium and potassium inside of the cell
- Na+: 12
- K+: 140
Sodium and potassium outside of the cell
- Na+: 145
- K+: 4
What causes death ultimately with hyperkalemia?
- Cardiac arrest
4 ECG changes that occur with yperkalemia?
- Tented T waves
- Decreased amplitude to no P waves
- Increased PR interval
- Wide QRS complexes
ULTIMATELY ATRIAL STANDSTILL
Atrial standstill
- Lack of P waves
- Just ventricular escape complexes
- Can lead to death ultimately
Treatment for hyperkalemia secondary to Feline Arterial Thromboembolism
- Dextrose +/- insulin
- Bicarbonate
- Calcium
- Furosemide
- IV fluids (BE CAREFUL)
Prognosis for arterial thromboembolism
- guarded to poor
- <40% survival
- HOWEVER, you CAN SAVE THESE CATS
- It’s worth trying
Negative prognostic indicators for feline ATE
- Number of legs affected + stiffness of legs
- Low Rectal temperature affected
- If you lose blood supply to GIT; brain; renal arteries
- Other sites
Regain of function for feline ATE
- Can happen!
- 3-6 months
Complications for feline arterial thromboembolism
- Necrosis
- Self mutilation
- Need for amputation
Things to monitor for cats with feline arterial thromboembolism
- Need to hospitalize for pain
- Monitor hyperkalemia
Recurrence rate for feline ATE
- 25-50% on clopidogrel
Hypertrophic obstructive cardiomyopathy etiology
- Idiopathic
- Might be a special type of HCM?
- Papillary muscle dysplasia?
Who gets HOCM?
- Cats mainly
Diagnosis of HOCM?
- DIAGNOSIS OF EXCLUSION!
- Echocardiogram
- Systolic anterior motion of the mitral valve
- If transient with stress –> no hypertrophy
- If obstruction –> concentric hypertrophy –> HOCM
- Obstruction of the aortic outflow tract during systole (dynamic stenosis)
- Can also have mitral regurgitation too
- Thoracic radiographs (r/o CHF)
Treatment for Stage B1 and B2 HOCM
- Slow heart rate to reduce SAM
- Beta blocker
- Diltiazem
Treatment for Stage C HOCM with CHF
- Furosemide
- ACE inhibitor
- +/- slow heart rate
- +/- Thoracocentesis
- +/- Pimobendan
- +/- Spironolactone
- +/- Anti-arrhythmics
Treatment for Stage C HOCM with ATE
- SUpportive care
- Pain management
- Antithrombotics (Aspirin, clopidogrel, low molecular weight heparin)
- Slow heart rate (Beta blocker, diltiazem)
Prognosis for Stage B1 and B2 HOCM
- Guarded to good
- Depends on response to decreased HR
Prognosis for Stage C HOCM with CHF
- Guarded 1-3 years
Prognosis for Stage C HOCM with ATE
- Guarded to poor
Etiology of restrictive cardiomyopathy
- Idiopathic
- AMyloidosis
- Fibrosis
Who gets restrictive cardiomyopathy?
- mainly cats
Diagnosis of restrictive cardiomyopathy
- Rule out secondary causes - DIAGNOSIS OF EXCLUSION (same list as with HCM)
- Echocardiogram
- Chest rads to check for CHF
Echocardiogram findings of restrictive cardiomyopathy
- Normal wall thickness (e.g. not HCM)
- Normal to reduced systolic dysfunction (e.g. not DCM)
- Diastolic dysfunction
Treatment for Stage B1 RCM
- No treatment
- Monitor
Treatment for Stage B2 RCM
- +/- ACE inhibitor
- +/- Beta blocker
- +/- Diltiazem
- +/- Spironolactone
- +/- Antithrombotic
Treatment for Stage C RCM with CHF
- Furosemide
- ACE inhibitor
- +/- Thoracocentesis
- +/- Pimobendan*** (if evidence of systolic dysfunction)
- +/- Spironolactone
- +/- Anti-arrhythmics
Treatment for Stage C RCM with Arterial thromboembolism
- Supportive care
- Pain Management
- Antithrombotics (aspirin, clopidogrel, low molecular weight heparin)
Prognosis for Stage B1 RCM
- Guarded to good
- May take years to progress
Prognosis for Stage B2 RCM
- Guarded
Prognosis for Stage C RCM with CHF
- 6-12 months?
- Guarded; may be worse than with HCM or HOCM
Prognosis for Stage C RCM with Arterial thromboembolism
- Guarded to poor
