Chapter 2 Cardiovascular System Flashcards
Which of the following is MOST likely to be associated with decreased central venous pressure (CVP)? A. Vasoconstriction B. Congestive heart failure C. Pericardial effusion D. Hypovolemia
D. CVP is a reflection of intravascular blood vol., cardiac function, venous tone and compliance, and intrathoracic pressure.
Congestive heart failure
Increases CVP due to cardiac dysfunction and poor forward blood flow
Pericardial effusion
Causes increase in CVP due to impaired diastolic function in the heart causing backup into the venous system
Vasoconstriction
Decreases venous compliance thus increasing CVP even in the face of hypotension
A five year old corgi was presented to your hospital and on physical examination is found to have a Doppler BP of 120/90 & HR of 80bpm. Calculate his MAP.
MAP = average blood pressure / time ( through systole and diastole). Diastole counts twice as much as systole as 2/3 of the cardiac cycle is spent in diastole. MAP= ((2 x diastolic) + systolic) / 3 = ( (2X 90) + 120 ) /3 = 100 OR 1/3 of pulse pressure added to diastolic pressure Pulse pressure is the difference between systolic and diastolic pressure MAP=diastolic + (systolic - diastolic) = 90 + (120-90)
Which medications is most likely to decrease after load in the heart? A. Hydralazine B. Furosemide C. Atenolol D. Lidocaine
After load = how hard to push the blood out fo the heart A. Hydralazine is a potent arterial dilator and by dilating the aorta, it will decrease the amount of pressure it takes to push blood out of the heart
Furosemide
Decreases vol. and therefore decreases preload
Atenolol
Beta 1 blocker and therefore slows HR, decreases contractility and slows conduction through the AV node
Lidocaine
Anti-arrhythmic and has no effect on afterload
Which of the following groups of medications would not be appropriate to use in a patient experiencing super ventricular tachyarrhythmia?
Vagolytic agents as it would block the vagus nerve from slowing the heart down and in some cases will actually increase HR i.e.Atropine
What do Calcium channel blockers, Beta blockers and digitalis glycosides have in common?
They all conduction through the AV node and could be used to treat a supraventricular tachyarrhythmia
What is a Tetralogy of Fallot?
A congenital defect that consist of 4 defects: Pulmonary stenosis (narrowing of the exit from the right ventricle) Ventricular Septal Defect (a hole between the two ventricles) Secondary right ventricular hypertrophy (thickening of the right ventricular wall) Over-riding aorta ( blood from both ventricles to enter the aorta)
According to the RECOVER CPR Guidelines, which of the following therapies should be used first in a patient in pulseless ventricular tachycardia (VT or vfib)? A. Biphasic defibrillation B. Vasopressin C. Lidocaine D. Epinephrine
Defibrillation. Then resume compressions and ventilation. EPI and vasopressins are second line treatment if there is prolonged pulse less ventricular tachycardia.
Which of the following heart conditions or disease states is NOT appropriately paired with a frequently associated clinical sign? A. Tricuspid valve dysplasia: ascites B. Feline hypertrophic cardiomyopathy: distal aortic thrombus C. Dilated cardiomyopathy: coughing and respiratory distress D. Pulmonic stenosis: Pulmonary oedema
D. Pulmonic stenosis is the narrowing of the right side of the ventricles which will likely show as ascites instead of pulmonary oedema
Tricuspid valve dysplasia
Leads to right sided heart failure signs = ascites
Feline HCM
Usually shows up in emergency for a thromboembolic event
Dilated cardiomyopathy
Left sided heart failure signs: Pulmonary oedema Coughing Lung congestion
Which of the following arrhythmias would be the least likely to auscultation in a rhythmic pattern? A. First degree AV block B. Second degree AV block C. Third degree AV block D. Bundle branch block
B. Second degree AV block would sound irregular due to dropped QRS’s
First degree AV block
Prolonged P-R intervals Regular rate and rhythm
Third degree AV block
All atrial impulses are blocked.
No communication between atria and ventricles, so each act completely independent of each other.
Requires the heart to function on an escape rhythm. Consistent P-P intervals Consistent R-R intervals Irregular P-R intervals
Right bundle branch blocks
Regular and fully functioning beats despite altered electrical pathways
What is an atrial standstill?
A rhythm created by the inhibition of atrial myocardial depolarisation secondary to hyperkalemia (K is greater than 7.5mEq/L) ECG most commonly shows absence P waves and wide bizarre QRS complexes with an overall slow rate. Rare cases: no P waves & narrow complexes, with biphasic T waves and a U wave after the T wave
What are the common diseases associated with the development of an atrial standstill?
Addison’s disease (Hypoadrenocorticism) Anuric or oliguric renal failure Uncontrolled DKA Metabolic acidosis Urethral obstruction Ruptured bladder
Which of the following cardiac conditions is primarily associated with a diastolic dysfunction? A. Dilated cardiomyopathy B. Heart worm disease C. Patent ductus arteriosus D. Feline hypertrophic cardiomyopathy
D. Diastolic dysfunction is the relaxation phase of the heart where it is allowed to stretch and fill. Hypertrophic cardiomyopathy is an issue of the ventricular walls stiffening and no longer stretching or allowing ventricular filling. Dilated cardiomyopathy is more related to the systolic phase and impaired contraction. Heart worm disease is an obstructive issue that leads to right side overload and right side systolic failure. Patent ductus arteriosus is a shunt issue between aorta and pulmonary artery creating a vol. overload to the left side of the heart and leading to pulmonary congestion and potentially oedema.
Based on a patient with atrial standstill, which of the following is the least likely the patient’s diagnosis? A. Hypoadrenocorticism (Addison’s disease) B. Inflammatory bowel disease C. Anuric renal failure D. Ruptured bladder
B. Inflammatory bowel disease causes severe diarrhoea which leads to a decrease in serum potassium due to GI losses Atrial standstill is due to hyperkalemia. Hypoadrenocorticism causes eleveated K levels. Anuric renal failure patients are no longer able to excrete potassium and therefore start developing hyperK. Patients with ruptured bladder will reabsorb K from the urine that is leaked back into the abdomen causing hyperK.
What is colloid oncotic pressure(COP)?
COP is a way of measuring the holding power of fluids within the vascular fluid compartment.
What is the normal COP measurement?
18-25mm Hg
At what COP measurement would synthetic colloids be used?
Below 3.5g/dL
Congenital Cardiac diseases or conditions
Patent ductus arteriosus (hole between pulmonary trunk and aorta) Ventricular septal Defect Tricuspid valve dysplasia Mitral valve dysplasia Tetralogy of Fallot (4 defects) Pulmonary stenosis
Specific acquired diseases or conditions
Feline hypertrophic cardiomyopathy (left ventricular hypertrophy) Canine dilated cardiomyopathy (ventricular dilation) Degenerative valvular disease (accumulation of mucopolysaccharides on Mitral valve) Infective endocarditis (bacterial colonization of heart valves and endocardium) Heart worm disease
Patent ductus arteriosus
Arterial duct that shunts fetal blood from pulmonary artery directly to the aorta results in appropriate flow of blood between aorta and pulmonary artery Congestive heart failure Need furosemide (diuretic) to reduce edema Left atrial enlargement can lead to atrial fibrillation - digoxin Watch for hypokalemia due to being on diuretic and digoxin Auscultable murmur of mitral regurgitation
Ventricular septal defect (VSD)
Hole in the interventricular septum which separates the left and right ventricles Most common cardiac anomalies in cats 4th most common in dogs Leads to left to right shunting May lead to right or left or biventricular failure
Second degree AV block, Mobitz Type 1
Progressive prolongation of P-R interval until a dropped beat occurs
P wave without a QRS after a series of prolonging P-R intervals
Also known as Wenckebach
Less likely to progress into third degree AV block
Causes:
Increased vagal tone
Fibrosis
drugs
Electrolyte imbalance
Second degree AV block Mobitz Type 2
P-R interval remains constant with intermittent P waves without QRS
More likely to progress to a 3rd degree AV block
QRS rhythm may or may not be regular depending on ratio of blocked beats
Hemodynamic compromise may occur if numerous dropped beats occurs
Atrial flutter
Rapid atrial rate where atrial repolarization is altered resulting in saw-toothed atrial complexes = F waves
QRS appear normal
Causes:
Valvular disease
Cardiomyopathy
Digitalis
Atrial Premature Complexes (APC’s)
Premature atrial beats that originate out of the SA node
ECG normal but rhythm is irregular due to premature P waves (P’ waves)
QRS normal or abnormal
Dangerous if P’ occur within S-T segment and disrupts heart depolarization
Causes:
Mitral valve insufficiency
Atrial diease
Chronic obstructive Pulmonary disease
Hypoxia
Right bundle branch block
Causes late depolarisation of the right ventricle.
Widening of ECG complex.
Alters direction of the current flow = Deep wide S wave.
Unaffected P and P-R interval.
No treatment required.
Left bundle branch block
Conduction delay or a block in both posterior and anterior fascicles of the left branch.
≈
*Right ventricle is activated first and then left ventricle activated late
-causes Wide QRS with positive deflection.
Sick Sinus Syndrome (SSS)
*Encompasses a number of sinus nodal abnormalities
*Can include sinus bradycardia, sinus arrest, sinoatrial block, alternating bradycardia/tachycardia and combination of SA and AV conduction disturbances or combination thereof
Atrial fibrillation
Numerous unorganised ectopic foci in the atria that discharge at very high rates causing uncoordinated activity in the atria.
ECG:
No defined P waves
Undulating baseline with erratic atrial activity
Irregularly irregular R to R intervals due to unpredictable communication to AV node.
Supraventricular tachycardia
Supraventricular = everything from AV node and above in the heart.
So it includes sinus tachycardia, atrial tachycardia and AV junctional tachycardia.
Regulat rhythm and between 260-350bpm.
Abnormal or irregular P waves, but hard to see as they are buried in T wave.
Sinus arrest and escape rhythms
Sinus arrest:
a pause between two normal complexes that is greater than two times the normal R to R interval due to lack of sinus node discharge.
Escape rhythms:
If pauses are long enough, the heart’s natural defence system will “escape” out of the natural pathway and initiate a beat from another region of the heart.
- AV node (junctional escapes): negatively deflected P wave or no discernible P wave and narrow complex QRS wave. 60-75% of patient’s normal sinus rate.
- Ventricles (ventricular escapes): no P wave and a wide and bizarre QRS complex. 1/2 of a normal sinus rhythm.
