Monday Lectures Flashcards
What is pressure?
Force applied to a surface per unit area
What two things does blood pressure rely on?
Location and phase of cardiac cycle
What are the two components of blood pressure?
Cardiac output/flow and resistance
What are the two components of cardiac output/flow?
Stroke volume and heart rate
What is the formula for resistance in a blood vessel?
Resistance = 8(length of the vessel)(viscosity of the blood)/3.14…(radius of the blood vessel)^4)
What is the most important factor that resistance depends on?
Radius of the vessel
What is the minimum systolic blood pressure necessary to be considered systemic hypertension?
Systolic BP > 160mmHg
What are the three different types of systemic hypertension?
Situational, secondary, and idiopathic
What is situational hypertension?
White coat syndrome → increased BP as a consequence of in-clinic measurement process
What is the main body system that is activated in relation to white coat syndrome?
Autonomic nervous system
Are animals with situational hypertension normotensive?
Yes
What can the persistent and pathologically increased blood pressure that defines secondary hypertension be due to? Three answers.
Disease/condition, therapeutic agent, and toxic agent
What two diseases are the most commonly found diseases to be affecting blood pressure and therefore causing secondary hypertension?
Renal and endocrine diseases
Listed below are the 4 mechanisms through which renal disease can cause secondary hypertension, give the blood pressure component (cardiac output and resistance) that will be affected:
- Sodium and fluid retention
- RAAS hyperactivation → increased sodium retention and vasoconstriction
- Sodium and fluid retention (Increased cardiac output)
- RAAS hyperactivation → increased sodium retention and vasoconstriction (Increased cardiac output and resistance)
Listed below are the 4 mechanisms through which renal disease can cause secondary hypertension, give the blood pressure component (cardiac output and resistance) that will be affected:
- SNS hyperactivation → increased sodium retention and vasoconstriction
- Vascular endothelial dysfunction → impaired NO production
- SNS hyperactivation → increased sodium retention and vasoconstriction (Increased cardiac output and resistance)
- Vascular endothelial dysfunction → impaired NO production (Increased resistance)
What are the two mechanisms of action that endocrine disease can cause secondary hypertension?
RAAS activation and increased sensitivity to aldosterone?
Is the systemic hypertension found related to hyperadrenocorticism/Cushing’s disease reversible?
Can be also cannot be
What organ system does diabetes affect that leads to increased blood pressure?
Renal
Why do pheochromocytomas cause episodic systemic hypertension, making it hard to diagnose?
The catecholamine release due to pheochromocytomas is episodic and the systemic hypertension is related to the catecholamine release
What are the two mechanisms by which hyperthyroidism causes secondary hypertension, especially in cats?
Increase cardiac output and increase sensitivity to sympathetic activation
Is the increase in blood pressure related to hyperthyroidism in cats mild or severe?
Mild
What two therapeutic agents can cause hypertension?
Corticosteroids and alpha agonists
What is the persistent and pathologically increase in blood pressure in absence of an identifiable underlying cause?
Idiopathic hypertension
Do cardiac diseases cause systemic hypertension?
No
Can systemic hypertension cause cardiac disease?
Yes
Why does systemic hypertension cause cardiac disease?
It increased afterload of the heart
What type of overload and hypertrophy does systemic hypertension cause?
Pressure overload → concentric hypertrophy
Is the heart disease due to systemic hypertension mild or severe?
Mild
What are the four organs that are particularly sensitive to systemic hypertension?
Kidney, eye, brain, and heart/vessels
What are the two renal sequela of systemic hypertension?
Decrease in renal function and early renal death
What would indicate the above renal issues that you could monitor in your patient?
- Above question: What are the two renal sequela of systemic hypertension? (Decrease in renal function and early renal death)
Increased renal values → BUN, creatinine; proteinuria
What is the ocular sequelae of systemic hypertension?
Retinal detachment
How would a patient with the above ocular systemic hypertension sequelae present to you?
(Retinal detachment)
With acute onset of blindness
Is systemic hypertension a frequent sole cause of congestive heart failure?
No, infrequent
What blood pressure does the doppler cuff method give you?
Systolic
Will a narrow blood pressure cuff over or underestimate blood pressure?
Overestimate
What is the first line choice of drug for severe hypertension (>200mmHg)?
Calcium channel blocker → amlodipine
What drug would you choose for cats with uncontrolled hyperthyroidism and that is contraindicated in dogs with pheochromocytomas?
Beta blockers → atenolol
If you are treating a cat for systemic hypertension and it also has proteinuria, what drugs would you use to treat this cat?
ACE inhibitor and calcium channel blockers → benazepril and amlodipine
Which of the drugs chosen above would you remove if the cat does not have proteinuria?
Benazepril
What abnormalities of the heart give it a ‘reverse D’ appearance on radiography?
Right heart and main pulmonary artery enlargement
Why do R → L shunt patients not respond to oxygen supplementation?
Because blood is skipping systemic circulation so higher levels of oxygen in systemic circulation isn’t going to help
What are the four cyanotic heart diseases?
rPDA, R to L VSD, R to L ASD/PFO, and tetralogy of fallot
Why are animals with cyanotic heart diseases at a higher risk of ventricular arrhythmias?
They will have concentric hypertrophy of the right ventricle d/t PH and PS + decreased oxygen content of blood = myocardium not getting enough oxygen → myocardium dies off → ventricular arrhythmias
If you see a GSD patient with a bad ventricular arrhythmia, what disease do they have?
Inherited ventricular arrhythmia
What are the breeds associated with juvenile dilated cardiomyopathy?
Portuguese water dog, doberman, and toy terriers
What is the term for transient loss of consciousness resulting from a decrease in cerebral perfusion?
Syncope
What are the three causes of syncope?
Cardiovascular, reflex mediated, and orthostatic hypotension
What do all cardiovascular abnormalities/diseases/conditions do that cause syncope?
Reduce cardiac output
What are the two groups of cardiovascular abnormalities that cause cardiovascular syncope?
Arrhythmias and others → structural obstructive heart diseases, pulmonary hypertension/PTE, pericardial effusion and congestive heart failure
What about the patient history would be more highly indicative of arrhythmic cardiovascular syncope?
If they animal is normal between episodes → arrhythmic
You auscultate a left sided diastolic murmur that is readily heard and of equal intensity to the S1 and S2 sounds, what grade and type of cardiac disease is this indicative of?
Grade 3, aortic valve regurgitation
(T/F) Horses may have normal performance and life-span with mild to moderate valvular regurgitation.
T
What three things would indicate the necessity of a cardiac work-up including echo, resting and exercise ECG?
Grade 3/6 murmur or higher, arrhythmias, and cardiac murmur with unexplained exercise intolerance
What are the two predisposing conditions for endocarditis?
IV injection and jugular vein thrombophlebitis
What is the most commonly endocarditis affected valve in cattle?
Tricuspid
What are the most commonly endocarditis affected valves in horses?
Aortic and mitral
What can occur secondary to tricuspid endocarditis or lymphoma in cattle?
Ruptured chordae tendineae
What are the two causes of mitral valve ruptured chordae tendineae in horses?
Idiopathic or secondary to endocarditis
What three locations can the aorta rupture into?
Pulmonary artery, pericardium or right of the heart
Would the murmur associated with aortic rupture be diastolic, systolic, or continuous?
Continuous
Though ventricular septal defects are typically associated with right sided systolic murmurs, they can also present with left sided systolic murmurs as a result of what two things?
Radiating sound or relative pulmonary stenosis
What does the impact on lifespan and athleticism depend on with ventricular septal defects? Two answers.
Size of the defect and direction of the shunted blood
What is cor pulmonale?
Pulmonary hypertension leading to right ventricular dilation/hypertrophy and right sided heart failure
What is the term for the disease that is due to relatively low oxygen concentrations at high altitude leading to hypoxic vasoconstriction of the pulmonary artery as well as hyperplasia and reduced diameter of pulmonary arterioles, resulting in pulmonary hypertension?
Ruminant high altitude disease aka brisket or high mountain disease
What is the treatment for high altitude disease, although prevention truly is the best strategy? Two answers.
Thoracocentesis to remove pleural effusion and remove to lower altitude
What is the ideal pulmonary arterial pressure when cattle are at higher altitudes?
< 41 mmHg
What should you not do with a cattle that has a pulmonary arterial pressure > 48 mmHg at higher altitudes?
Breed them → susceptibility is heritable
What are the three types of pericarditis?
Effusive, fibrinous, and constrictive
What is the most common cause of pericarditis in cattle?
Traumatic reticulopericarditis
What is the most common cause of pericarditis in equine patients?
Idiopathic
What is the suspected etiology of Actinobacillus spp. inoculation in the pericardium?
Ingestion of Eastern tent caterpillars
What are the common locations for lymphoma in large animal species?
Right atrium, mediastinum, and pericardium
What is the transmissible virus that causes lymphoma in cattle?
BLV, bovine leukemia virus
What is the arrhythmia that is typically normal, non-pathologic in equine patients?
2nd degree AV block
What are bradyarrhythmias, which are often detected in health horses, associated with?
High parasympathetic tone
What is an important characteristic of non-pathologic arrhythmias in horses?
The are present at rest and disappear with an increase in sympathetic tone such as exercise
What is the term for the irregularly irregular arrhythmia characterized by lack of p waves and normal, irregular QRS complexes?
Atrial fibrillation
A treatment option for atrial fibrillations is administration of quinidine which is a sodium channel blocker that also affects potassium channels to have what effect on refractory period and action potential conduction?
Prolongs the refractory period and slows AP conduction
(T/F) All arrhythmias are pathologic and abnormal in cattle.
True
When do arrhythmias most commonly occur in cattle?
When the animal is off feed and/or with GI disease
What do urinary tract obstructions or uroabdomens increase that can cause bradycardia, atrial arrest, and death in small ruminants and camelids?
Hyperkalemia
What does the resulting change in excitation potentials of cardiac myocytes due to inflammation, necrosis, and/or fibrosis result in? Three answers.
Arrhythmias, brady/tachycardia, and poor cardiac contractility
Nutritional myodegeneration is caused by the deficiency of what two substances/minerals?
Vitamin E and selenium
What species is very susceptible to ionophore intoxication?
Horses
Why are ionophores often added to livestock feed?
To treat coccidiosis
Will horses with ionophore toxicity have decreased or increased left ventricular fractional shortening?
Poor cardiac contractility → decreased left ventricular fractional shortening
