Cardiovascular Flashcards by Theresa Blakey

What are causes of pericardial disease in cats

Left sided CHF (#1)
Neoplasia - lymphoma/adenocarcinoma (#2)

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MOA of digoxin and what are indications

Na-K ATPase inhibitor (increased intracellular Na –> decrease in Na-Ca exchange –> increased Ca leads to increase in strength of contraction

Ionotrope (pump better)

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What electrolyte abnormality can be seen with digoxin

Hyperkalemia (blocks the Na-K pump that results in less K being pumped into the cell

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What are two heart diseases in dogs that are exclusively arrhythmogenic?

ARVC (boxers) and inherited sudden cardiac death (GSD - ventricular)

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What is torsade de pointes

Ventricular arrhythmia leading to tachycardia that arises from prolongation of QT intervals.

Rhythm prior is slow and the QT interval is prolonged along with R-on-T extrasystole

The occurs a rapid ventricular rhythm has QRS complexes that are regular, but changing amplitude and polarity

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What is sick sinus syndrome

AV conduction disturbances and disturbances of supraventricular/ventricular excitability.

Breeds - Min. schnauzers, cockers, westies

ECG: 1st or 2nd degree AV block with prolonged sinus pauses and escape beats –> bursts of supraventricular tachycardia

Dx - atropine response –> normal heart will have an increase in rate

Tx - if there is a response to atropine –> theophylline/aminophylline, proapantheline, hycosamine; no response pacemaker

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What test is more sensitive for heartworm detection in the cat compared to dog

echocardiogram

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Which test should be used as a screening test for feline HWD

HW antibody

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What is responsible for the S4 heart sound?

Atrial contraction (atrial kick)

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S3 heart sound?

rapid ventricular filling

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S2 heart sound

aortic valve closing

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S1 heart sound

mitral valve closing

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what valvular condition predisposes a patient to endocarditis

subaortic stenosis

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What is isovolumic contraction

period just before ventricular ejection –> pressure is rising while volume stays the same –> all valves are closed (up on curve)

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What is isovolumic relaxation

period just after ventricular systole –> pressure is decreasing in ventricles and volume stays the same –> all valves closed (down on curve)

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Where are baroreceptors peripherally

carotid and aortic bodies

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What stimulates baroreceptors

hypoxia, and changes in BP –> when carotid baroreceptors detect MAP < 100 mmHg –> stimulates vasomotor centers to decrease parasympathetic and increase sympathetic output

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Where are central barareceptors

medulla - respond to increased CO2 and H

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Where are chemoreceptors and what do they respond to?

Peripheral - carotid/aortic –> hypoxia, increased CO2, and acidosis

Central - medulla –> increased CO2 and acidosis (NOT hypoxia)

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What condition would cause a hyperdynamic pulse

PDA and aortic insufficiency

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What neurohormone is inactivated in the lungs

bradykinin and angiotensin I and PG

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What congenital heart disease causes splintered QRS wave on ECG

Tricuspid valve dysplasia

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What is the most common congenital heart condition in cat

Ventricular septal defect (VSD)

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What is the major stimulus for aldosterone

hyperkalemia

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What is the major stimulus for ADH

increased osmolarity of the blood

What are the phases of a cardiac myocyte action potential (non-pacemaker cell)

Phase 0: depolarization --> Na IN (fast) Phase 1: initial repolarization --> K OUT and fast Na channels close Phase 2: plateau --> Ca IN (slow) and K OUT Phase 3: rapid repolarization --> K OUT Phase 4: resting --> K IN and Na out --> maintenance

What are phases of SA node action potential (pacemaker cell)

Phase 0: depolarization --> Ca IN (L type channels) Phase 3: repolarization --> K OUT Phase 4: resting membrane (no true RMP) - slow depolarization caused by Na IN and K OUT and small amount Ca IN nearing depolarization --> accounts for pacemaker activity

What is perfusion pressure

systolic pressure - diastolic pressure

How is the radius of a blood vessel related to blood flow

Poiseuille's Law --> resistance = viscosity x length of vessels/r^4 decreasing the radius will increase the resistance more leading to a decrease in blood flow `

What is ANP

atrial natriuretic peptide Secreted by atrial myocytes with atria is stretched Leads to increase Na excretion by increasing GFR (dilates afferent and constricts efferent). Also relaxes vascular smooth muscle

What are examples of cardiac glycosides

foxglove and digitoxin

What are the stages of MMVD

Stage A: at risk - cavaliers Stage B1: murmur - no cardiac enlargement Stage B2: murmur - cardiac enlargement Stage C: CHF Stage D: refractory CHF

MOA pimobendan

phosphodiesterase 3 inhibitor (leads to increased Ca) --> increases contractility inodilator

What is responsible for the automaticity of the SA node

Slow Na and Ca channels

What vasoactive factors are decreased in pulmonary hypertension

Nitric oxide

What are causes of pulmonary hypertension

Pulmonary arteriolar vascular disease (parasites -HWD and angiostrongylus & congenital - ASD, PDA< VSD) Left sided heart disease (pulmonary venous hypertension --> MMVD, myocardial disease) Pulmonary disease (COPD, high-altitude, interstitial pulmonary fibrosis neoplasia, tracheobronchial disease) PTE HWD

What are the components of tetralogy of fallot

VSD RV hypertrophy PS Overriding aorta

In relation to cardiac myocyte (non-pacemaker) action potential what channels are open during phase 0 depolarization?

Fast Na channels

How much will A-fib decrease cardiac out by

25-39% and it increases ventricular filling pressure

What are class Ia antiarrhythmics

Fast Na channel blockers; quinidine, procainamide, disopyramide

What is the MOA of class Ia antiarrhythmics

Na channel blockers --> phase 0 Use with ventricular arrhythmias

What are class Ib antiarrhythmics

intermediate Na channel blockers phase 0; lidocaine, phenytoin, mexiletine Use with ventricular tachycardia and atrial fibrillation

What are class II antiarrhythmics

Beta blockers (adrenergic); propranolol, atenolol, carvedilol Negative inotrope and negative chronotrope

What are class II antiarrhythmics

amiodarone and sotalol K+ channel blockers --> phase 3 ventricular tachycardias and atrial fib

What are class Iv antiarrhythmics

Slow Ca channel blockers --> prolongs refractory period Prevent ventricular rate in patients with a-fib

Is digoxin rate or rhythm control?

rate

What is ANP function and clearance

Atrial natriuretic peptide --> produced by atrial myocytes in response to stretch of atria Function: *kidney --> increase Na excretion (dilates afferent arteriole increases GFR) *Vessels --> increases capillary permeability and relaxes vascular smooth muscle *inhibits renin secretion and ADH

What are central chemo receptors

medulla (sensitive to pH and altered breathing)

What are peripheral chemoreceptors

Carotid and aortic bodies

What cardiac disease is seen with bounding arterial pulses

aortic insufficiency

What receptor causes release of Ca from the sarcoplasmic reticulum

Ryanodine receptors

Hormones that cause vasodilation

epi(liver and SKm), bradykinin, histamine, PG

Hormones that cause vasoconstriction

AT II, vasopressin, norepo, epi (kidneys/skin)

Where in the sarcomere is the action potential generated

T-tubules

What is the anti-thrombotic effect of vascular endothelium

thrombomodulin

What increases cardiac contractility

myofibril stretch

What substances are affected with pulmonary hypertension

decreased prostacyclin and NO increased endothelin, thromboxane A2, serotonin

Young GSD regurgitating and not gaining weight

PRAA

What is the gold standard diagnosis for PTE

CT angiogram

What are cardiac biomarkers

BNP (NT-proBNP) ANP (NT-proANP) Cardiac troponin

Cause of PDA

failure of the ductus arteriosus muscle to constrict - leaves passage for blood to flow from aorta to pulmonary circulation (L to R shunt) leading to left sided heart disease

Causes of pulmonary hypertension in dogs

left sided heart disease HWD PTE idiopathic/primary chronic lung disease

what breed are predisposed to DCM

golden - taurine

L to R shunt of PDA causes what

left sided volume overload

HCM pathologic finding cat

left concentric ventricular hypertrophy maine coon MyBCP3

How do you treat 2nd degree AV block

atropine, terbutaline, aminophylline, propantheline