Flashcards in Exam 3 Deck (75)
Mode of inheritance for HCM in cats?
Which protein is mutated in HCM?
Cardiac myosin binding protein C
2 cat breeds over-represented for HCM?
HCM is a disease of _____ dysfunction
Name 2 consequences of the altered Ca handling that occurs with HCM
1) Ca gets left in cytosol during diastole-->incomplete ventricular relaxation
2) myofibrils become more sensitive to Ca
The hallmark histopath finding for HCM?
Is gross examination of a heart that has LV concentric hypertrophy sufficient for a diagnosis of HCM?
Name 3 reasons murmurs can occur with HCM
2) septal hypertrophy leading to LVOT obstruction
3) RVOT obstruction
What arrhythmias are commonly seen with HCM?
Arrhythmias are uncommon with HCM!
BUT, VPCs are most common (supraventricular arrhythmias are more rare)
1/2 the cats that develop CHF with HCM get it because of what reason?
a precipitating event (i.e. they were sick and then given IV fluid therapy, or went under anesthesia)
As far as lung involvement, is edema or effusion more common in cats with HCM?
Most notable ECG finding for cats with HCM? And the cause?
Left axis deviation
Left anterior fasicular block
T/F: if an infiltrative disease causes left ventricular concentric hypertrophy, treatment of the primary disease will resolve the hypertrophy
What is the primary indication for use of beta-blockers in treating HCM?
when there is a LVOT obstruction from SAM
*increased filling time helps more blood enter and push valve away from the outflow tract*
A contraindication for use of beta-blockers in HCM?
when the patient is in ACTIVE CHF... need to maintain CO and beta-blockers will slow HR too much
HCM tends to be more aggressive in?
Young, male purebred cats
A disease of diastolic dysfunction due to non-compliant ventricular walls
Restrictive cardiomyopathy (RCM)
As fibrosis in RCM progresses, what can develop?
can progress to systolic dysfunction
Which thoracic radiograph finding is most common in cats with RCM?
left or biatrial enlargement
On ECG, which arrhythmia is most common with RCM?
Concerning Tx of RCM:
1) which medications are indicated if systolic dysfunction is present?
2) if systolic dysfunction is present, which class of drugs may not be the best choice?
DCM is a disease of ____ dysfunction
Describe how Mitral/tricuspid regurgitation can occur with DCM
when the chambers dilate, they pull the leaflets apart (annular stretch), creating a gap
The most common physical exam finding for cats with DCM?
S3 gallop sound
Which two classes of drugs are indicated for use in treating DCM?
1) positive inotropes
2) anti-arrhythmias (but not beta-blockers!!)
Two actions of Pimobendan?
1) calcium sensitizer (allows less Ca to stimulate a stronger contraction)
2) PDE III inhibitor (vasodilation & increased Ca release and uptake)
T/F: if Taurine deficiency is the cause of DCM, supplementation may return systolic function to normal
The gold standard for diagnosing taurine-deficient myocardial failure?
Myocardial biopsy (but it's not practical)
The cause of most cases of arterial thromboembolic disease?
severe cardiac disease (HCM, RCM, DCM)
Name the 3 components of Virchow's triad
Which component of Virchow's triad is most important in cat ATE?
What is the most important factor for determining severity and recovery with ATE disease?
constriction of collateral circulation
Concerning anti-platelet drugs in cats:
1) which is a good sole agent?
2) which is not recommended in cats due to risk of hemorrhage?
The difference between staging a patient as B1 vs. B2?
B2--cardiomegaly is present
FIRST sign of R-CHF in:
1) ascites (comes later in cats)
2) pleural effusion (comes later in dogs)
Name the 3 affects of sympathetic stimulation on the heart/vasculature
1) stimulates contractility (beta)
2) increases HR (beta)
3) systemic vasoconstriction (alpha)
Name the important effects of AT-II (5)
1) increases aldosterone (Na retention)
2) increases ADH (saves water)
3) increases thirst and Na cravings
4) activates sympathetic adrenergic system
5) fibrosis of heart and kidney
4 classes of drugs commonly used in treatment of CHF?
How is efficacy of diuretics measured?
by seeing a 5-8% decrease in body weight (w/in 8-12hrs)
Primary site of action for loop diuretics?
And what is their action?
Thick ascending loop of henle
Inhibition of Na/K/Cl co-transporter
Which loop diuretic it the best choice for rapid diuresis?
What is the outcome of long-term use of loop diuretics?
--hypertrophy of distal tubule cells (get better at saving Na)
Site and mechanism of action for Thiazide diuretics?
early distal tubule
inhibition of Na/Cl co-transporter
Thiazide diuretics are best reserved for what patients?
Those that are no longer responding to Furosemide (refractory CHF)
Site and mechanism of action of K-sparing diuretics?
Late distal tubule & early collecting duct
Aldosterone antagonist (competitive inhibition)
Which class of diuretics is weak on its own and should therefore always be used in combination?
2 impacts of RAAS activation on the myocardium?
1) induces apoptosis of healthy cardiomyocytes
2) induces cardiac fibrosis
Give two advantages of Benazapril
1) not eliminated entirely in the kidneys (better choice if renal dysfunction is present)
2) can be give once a day (good for cats!!)
Why are K-sparing diuretics useful in treating PLN?
cause dilation of the efferent renal arteriole (decreases GFR)
**This is also why they have the potential to cause kidey damage**
What class of drug is Dobutamine?
What is the action of dobutamine and how does it change with dose?
increases cAMP & Ca levels
1) low dose: inotropy with little vascular effects
2) high dose: increases vascular resistance
An L-type Ca channel blocker that causes arterial specific vasodilation
Which drug is able to cause dilation of both arteries and veins?
1) should be used cautiously in patients with liver dz?
2) can cause cyanide toxicity with prolonged use?
3) causes the most profound decreased in BP?
Which drug increases venous capacitance to decrease preload?
Contraindication for vasodialtors in acute L-CHF?
outflow tract obstruction
Increased pulmonary arterial pressure
What is cor pulmonale
Right heart disease that develops secondary to pulmonary disease (usually PH)
Gold standard for diagnosis of PH?
(invasive and not practical)
Two goals of PH therapy?
1) treat underlying disease
2) prevent vasoconstriction and improve oxygen delivery
Main drug used to treat PH and it's MOA?
PDE-V inhibitor (prevents cGMP breakdown so NO can stay around longer)-->improved vasodilation
Main site of storage for Pro-BNP and pro-ANP peptides?
Atrial myocytes (as granules)
*pro-ANP >> pro-BNP
When cleaved, which end of the peptide is the active hormone?
How do natriuretics work?
promote Na (water) excretion by inhibiting tubular Na uptake in collecting ducts
What stimulus causes the release of natriuretic peptides?
atrial stretch and volume overload stress
Which natriuretic peptide is significantly upregulated with CHRONIC volume overload?
Two methods for removal of natriuretic peptides?
1) bind to clearance receptors
2) Neutral endopeptidases
What causes the release of cTnI?
Two important sources of stem cells in the heart?
Two causes of increased pericardial pressure?
Severe pericardial effusion
Stiff pericardium (constrictive pericarditis)
Two most common causes of pericardial effusion:
2) Cat (has 3)
1) Neoplasia & Idiopathic
2) Neoplasia (lymphoma), R-CHF, FIP
4 tumors that can occur in the heart
2) heart base tumors
Name the most common location for each of the cardiac tumors
1) hemangiosarcoma--R auricle
2) heart base tumors--great vessels (aorta, pulmonary artery)
3) lymphoma--LV myocardium
4) mesothelioma--doesn't form a mass
3 ECG findings associated with cardiac tamponade
1) sinus tachycardia (100%)
2) Low QRS amplitude (100%)
3) Electrical alterans (alteration in R wave amplitude... 25%)