This is the filling time of the ventricle on an ECG
P-R interval
This is the filling time for the atrium on an ECG
S-T segment
This is the measurement of the left ventricle
Blood Pressure
This is the percentage capacity at which is considered normal heart function
25-35%
This is the difference between the work capability at rest and that during maximum physical exertion
Cardiac reserve
O2 availability to the tissues depends on:
1. cardiac output
2. amount of O2 extracted from the blood
What two systems generate blood pressure?
General vascular system - left ventricle
Pulmonary vascular system - right ventricle
Blood pressure on the arterial side is maintained by:
1. Cardiac output
2. Total Peripheral Vascular Resistance (TPR)
Mean Arterial Pressure is determined by:
the product of the level of cardiac function (cardiac output) and the degree of arteriolar constricture (TPR) MAP = CO x TPR
These are released from the atria of the heart in response to increases in blood volume and atrial filling
Atria Natriuretic Peptides
The functions of ANPs are:
1. Promote urinary excretion of Na+ and H2O by direct action on the tubules in the nephron
2. Reduce TPR by relaxing arterioler vascular smooth muscle
What are the two paracrine agents that regulate arteriolar pressure and cardiac output?
Nitric Oxide
Endothelin
This is a local vasodilator released by endothelial cells in the linings of many blood vessels
Nitric Oxide
This is a peptide released by endothelial cells in blood vessels that constrict vascular smooth muscle
Endothelin
These two agents are known to stimulate the release of endothelin
Angiotensin II
Nor-epinephrine
This is where the blood flows is continuous and controlled by arteriolar sphincters in the wall
Arterio-venous capillaries
Another name for Arterio-venous capillaries
"Thorough-fare" capillaries
This type of capillary has no muscle where the change in flow is produced by tissue needs and pressure gradients via passive diffusion
Secondary capillaries
Secondary capillaries are also known as:
"True" capillaries
Venous return to the heart is controlled by:
Inspiration - negative intra-thoracic pressure acts like a vacuum to pull blood to the heart
Venous Contraction
Valves
Heartbeat
Muscular activity - walking
Peristalsis and intestinal activity
Gravity
What is the percentage of chronic mitral disease in heart patients?
70%
What percentage has heart involvement in disease?
13%
What percentage of heart disease is related to Dilated Cardiomyopathy?
8%
This is the failure of the opening between the pulmonary artery and the aorta to close at birth that is the most common inherited pathology in companion animals
Patent Ductus Arteriosus
What is the Ductus Arteriosus supposed to become upon birth?
Ligamentum Arteriosum
A treatment for mitral value insufficiency that is associated with restricted amounts in the diet
sodium restriction
A treatment for mitral valve insufficiency that is associated with drugs that draw water from the body and increase urination.
Diuretics - Furosemide (Lasix), spironolactone
A treatment for mitral valve insufficiency that is associated with drugs that keep the blood pressure low which reduces the blood backing up into the lungs
ACE inhibitors:
Enalapril Maleate (Enacard - veterinary)
Benazepril (Fortekor - human)
A treatment for mitral valve insufficiency that is associated with drugs that cause vessels to dilate and increase the afterload of the heart
Vasodilators:
Hydralazine
A treatment for mitral valve insufficiency that is associated with drugs that promote cardiac contraction
Positive Inotrope:
Pimobendan (VetMedin)
A treatment for mitral valve insufficiency that is associated with drugs that lower the heart rate
Digitalis glycosides (Digoxin, Cardoxin)
A treatment of mitral valve insufficiency that is associated with drugs that keep stimulation of the heart by catecholamines low.
Beta Blockers:
Carvedilol
This is seen on an ECG as slightly wavy line with an occasional escape complex
Sinus arrest
This prohormone can give an indication of impending myocardial infarction in humans and myocardial condition in animals
B-type Natriuretic Peptide (BNP)
This is the process of excretion of sodium in the urine by action of the kidneys
natriuresis
This is a peptide similar to ANP and is secreted by the left ventricle in response to wall stretch or stress which can be isolated by Idexx or Antech to predict heart failure
NT-proBNP
What value of NT-proBNP is considered normal?
0-900 pmol/L
What value of NT-proBNP indicates heart disease?
900-1800 pmol/L
What value of NT-proBNP is indicative of heart failure?
>1800 pmol/L
This explains that some postganglionic receptors of the sympathetic nervous system release acetylcholine (are cholinergic)
Grey Rami
What 3 structures only have sympathetic innervation?
HAS
Hair folicles (piloerector muscles)
Adrenal Medulla
Sweat Glands
This is the poison from toadstools that only activates the receptors at the postganglionic synapse of the parasympathetic system
muscarine
Epinephrine excites with receptors
Alpha and Beta
Norepinephrine excites which receptors?
Mainly alpha
What two effects do catecholamines produce?
Vasoconstriction
Vasodilation
With the exception of intestinal smooth muscle alpha receptors are basically what?
stimulatory
With the exception of cardiac muscle beta receptors are bascially what?
inhibitory
A phase of shock where all the arterioles except coronary and cerebral constrict to shunt blood from the periphery to internal organ, maintain blood pressure, and increase cardiac output
Compensatory
A phase of shock where the heart can no longer pump sufficiently due to fatigue which reduces cardiac output and O2 causing respiratory and vasodilation
Progressive
A phase of shock where damage to the heart is too great to be treated, resulting in death
Irreversible
This is the reason why vessels vasodilate
To reduce friction on the blood so it flows more easily.