SEE BASIC SCIENCES : A & P Review Flashcards
Carotid sinus located where
internal carotid artery
Why is the carotid sinus important?
They have receptors that are responsible to normal BP to the brain
PEA causing factors include H & Ts
Hypoxia H+ (acidosi) Hyperkalemia Hypovolemia Hypothermia PE Tension Pneumothorax Tamponade Toxins
Can PEA be treated with defibrillation
NO
Treatment options for PEA
Epi 1mg 3-5 minss
Vasopression 40 units IV
Drugs that can be give through ETT tube with people with no IV access? (LANE) or NEAL
Lidocaine
ATropine
Narcan
Epinephrine
Maximum delivery for monophasic defibrillation?
360 J
Adenosine given paroxysmal SVT, what may occur with admin of that drug?
Bradycardia with brief asystole
How does Adenosine work?
Slow the electrical conduction of signals through the AV node to afford a reset of heart rhythm to a normal rhythm
What is the best description of a 2nd degree HB type II (Morbitz II)
A constant and set PR interval, the ventricular is slower than the atrial rate.
In HB type 2 Mobitz type II , P-R interval is______but what about the P wave?
constant; not every P wave is followed by a QRS complex. , atrial rate is greater than ventricular rate.
3 tx options for 2nd degree HB
Isoproterenol
Dopamine
Trascutaneous pacemaker
Epi 2-10 mcg/min
What is the goal of treatment for a patient with Mobitz type II?
Increasing the HR, as needed to achieve adequate cardiac output
In 2nd degree type I (wenckebach) , where is the pathology ?
AV node
What describe 2nd degree type I?
Progressing lengthening or increase in P-R interval until a QRS is lost due to lack of impulse conduction through the AV node.
Torsades is a disturbance of the _____Phase of the cardiac cycle and is associated with ______QT
repolarization ; prolonged
Vfib , no pulse , no respiration, 1st action?
Defibrillate
How do you know when the pacemaker is not capturing?
Pacemaker is not followed by QRS and occur randomly .
What is the THRESHOLD potential?
Potential to which a membrane must be depolarized to initiate an action potential.
Cardiac membrane depolarization occurs at what phase?
phase 0
Threshold potential is achieved to produce an
action potential represented by the QRS complex.
In what phase of the cardiac action potential has a reduction in Na+ permeability , a transient outword K curent and an outward Cl- current?
Phase 1
Outflow of which ion that inactivates the fast Na+ channels?
K+ and Cl-
What is the mechanism of tachydysrhythmias?
Increased automaticity in normal conduction tissue or in ectopic focus rather than the SA node
Parasympathetic NS stimulation results in which of the following?
A decrease in the SLOPE of PHASE 4 depolarization resulting in a slower HR
Which of the following is true regarding dysrhythmias 2nd to an ectopic focus? (onset)
they have a gradual onset. It insidiously take over the normal generation of the cardiac cycle.
Which of the following are true about re-entrant dysrhythmias ?
They occur along embryological remnants of tissue around the AV node.
What is the most common of premature beats as well as tachydysrythmias, originate secondary to
re-entry pathways of electrical stimuli in the myocardium
In normal pacemaker sites within the heart, the conductime through the _____is the slowest in the heart?
Purkinje fibers
SA node is directly innervated by the
Vagus nerve
SA node stimulation rate
60-100
AV node stimulation rate
40-60
Purkinje stimulation rate
20-40
Variation of the HR in response to changes in intrathoracic pressure during inspiration and expiration is due to which of the following?
Bainbridge reflex
Bainbridge reflex aka
Atrial reflex
What is the Bainbridge (Atria) reflex?
Its a reflex that is triggered by input from atrial stretch receptors resulting in a compensatory increase in HR.
What is the most common supraventricular dysrhythmias associated with acute MI?
Sinus Tachycardia
What is GU symptoms associated with SVT?
Polyuria
What is the mechanism of Polyuria with SVT?
Increase in the secretion of ANP in response to increase atrial pressure from contraction of the atria against closed AV valves.
Most common post operative tachydysrythmias after cardiac surgery?
Atrial fibrillation
Independent risk factors for afib after cardiac surgery?
DM
Valvular disease
CHF
Age, (elderly)
When giving anesthesia to a patient with a known hx of WPW , anesthesia provider should do the following? Avoid what medications
Avoid Digoxin, and CCB
When giving anesthesia to a patient with a known hx of WPW , anesthesia provider should do the following? Avoid what ?
Stimulation of SNS is avoided
When giving anesthesia to a patient with a known hx of WPW , anesthesia provider should do the following? What do you do with fluids?
Limit IV fluids because Atrial-ventricular dyssynchrony may cause acute fluid overload.
Wolff Parkisons white syndrome is characterized by inappriate
ANTEROGRADE conduction of cardiac impulses via an accessory pathway.
With WPW , anesthetist should avoid to
Enhanced aberrant conduction
Consideration for asthma patient with long QT syndromes
PREOP incremental loading dose of METOPROLOL 5mg IVP
Possible mechanisms of asystole during spinal and epidural anesthesia include which of the following.
The BEZOLD-JArisch response
The Bezold Jarisch reflex , results from
initiation of vagal reflex arcs by the decrease venous return associated with spinal or epidural to result in a REFLEX- induced bradycardia.
Profound bradycardia and cardiac arrest during neuraxial anesthesia is
Less common than cardiac arrest during GA
Characteristics of BBB: –> RBBB
rSR’ QRS complex in leads V1-V2
Deep S wave in I and V6
Does RBBB always imply cardiac disease?
No
Which is more common in patient without structural HD?
RBBB vs LBBB
RBBB
Characteristics of BBB: –> LBBB
Absence Q wave in I and V6
ST and T waves changes are already present (repolarization abnormality)
PA contraindicated in patients with
LBBB; may lead to RBBB
SVT combined with this BBB can be mistaken for ____
Left BBB; VTACH
Single MOST important factor that increases survical in patient with VFib
Defibrillaiton within 3-5 minutes of onset
Atrial systole (atrial kick) accounts for ______% of CA
20-30%
Maximization of CO occurs as the result of
Atrial contraction
Where is the Effective Refractory period?
Period that extends from the QRS complex to near the top of the T wave.
What is the Effective Refractory period?
Period of time when no contraction will occur no matter how strong the stimulus.
what is the relative refractory period?
Late stage of repolarization during which a second action potential may be generated by a sufficiently large stimulus.
In a normal distribution of blood volume, where does the major %of blood exist?
Venous circulation. Systemic circulatory circulation, the venous network is more compliant and distensible, with the greatest capability
Most of the deoxygenated blood from the myocardium drains into a large vascular sinus called the ________
Coronary sinus
The Coronary sinus empties in the
Right Atrium
The semilunar valves allow the ejection of blood from the _________ into the _______through valves that consists of ______cusps each
Ventricles: artery ; 3
How many cusps in semilunar valves
3 cusps
Which layer of the valve is responsible for the major pumping action of the ventricles?
Myocardium
What are the 2 most important preop risk factors for about about to have a surgical procedure?
Unstable Coronary syndrome
CHF
Assessment of which system is paramount for the patient going for surgery?
Cardiac
Pt SV of 70ml, HR 80, pulmonary artery mean pressure of 20mmHg. and a CVP of 15 will have which CO ?
5.6
Formula for CO
SV x HR
Which fibers primarily innervates the atria and conducting tissues?
Parasympathetic
Innervation of the SA comes via the
right vagus EFFERENT FIBERS
Stimulation of Parasympathetic system results in
negative chronotropic
dromotropic
inotropic effects
Vascular tone and autonomic influences on the HR are controlled by vasomotor centers in which area?R
Reticular formation of the medulla oblongata and lower pons
Chemoreceptors in the carotid and aortic bodies detect all the following except?
Blood pressure
Receptors that detect change in BP
Baroreceptors
What stimulates chemoreceptors?
Decreasing O2 tension and increasing {H+} concentration , which results in increase pulmonary ventilation and BP with decreased HR
Chemoreceptors respond to
Alteration in chemical component, their concentration, and acidity and alkalinity to communicate.
Where are baroreceptors found?
Carotid sinus and aortic arch
What are baroreceptors innervated by ?
Sinus nerve of Herring
Role of baroreceptors? What do they monitor?
Regulate the autonomic control of heart and blood vessels.
They monitor pressure and volume changes and communicating those changes to the CNS via the sinus nerve of herring, CN IX , and CN X
3 nerves that baroreceptors communicate via
Sinus Nerve of Herring
CN IX
CN X
What is the CAUSE of the greatest myocardial O2 requirement?
Pressure work (to force blood through the body , 64%.
T/F As a determinant of myocardial blood flow, MAP is more important than Arterial diastolic pressure?
False; Coronary perfusion pressure is actually determined as the difference between aortic diastolic pressure ( ADP) and LVEDP. CPP = ADP-LVEDP
Coronary Artery blood flows from
Epicardial to ENDOCARDIAL
Coronary arteries receive blood for the myocardium as they emergy from the aorta and traverse the outside of the heart the _______ to branch and infiltrate the heart muscle, eventually terminally reaching the
Epicardium; inside of the heart, the endocardium
83 yo pt with HR of 46, and takes no medication that that would slow the HR. Which part of the electrical system is acting as the cardiac pacemaker?
AV nodes.
Right atrial pressure is
0-8 mmHg
Left atrial pressure is
3-12 mmHg
RV systolic pressure
15-25 mmHg
Pulmonary artery diastolic pressure
8-15 mmHg
Close approximation of the left atrial pressure is obtained through
Pulmonary capillary wedge.
What is the normal coronary artery blood flow at rest?
225- 250ml/min
When is the LV perfused?
Almost entirely during diastole
The RV is perfused when?
Both systole and diastole
Is coronary perfusion continous ?why or why not?
Not continuous ; it is interrupted with every contraction, Coronary perfusion is intermittent.
Which alpha receptor subtype is responsible for vasoconstriction?
Alpha 2B
Chief functions for alpha 2A adenoceptors are
Sedation
Hypnosis
Analgesia
And sympatholysis
Chief functions for alpha 2B adenoceptors are
Mediate vasoconstriction
Clonidine alpha 2 to alpha 1
200 time more specific for alpha 2 than alpha 1
Terminal elimination half life of Dexmedetomidine?
2 hours
What is elimination of Half life?
time required for 50% of a dose of medication to be removed from the plasma.
Clonidine and dexmedetomidine are part of which chemical class of Alpha 2 adrenergic agonists?
IMIDAZOLINES
IMIDAZOLINES compound found in precedex contain
Nitrogen andamine bonds.
act on CNS to decrease spasticity with significantly less muscle weakness.
Clonidine advantage prior to giving anesthesia reduces
Myocardial energy requirements and improves myocardial oxygen balance.
Clonidine and LA
Increase the duration of action when used with LA for neuraxial blockade.
Clonidine and TEMP
clonidine affect thermoregulatory control.
Clonidine and IV and VA
Decrease requirement , originally used from HTN crisis.
Abrupt discontinuation clonidine can lead to
Rebound HTN
Which medication can be given with patient with rebound HTN from clonidine?
Labetalol.
Following abrupt discontinuation of adrenergic blockers, which is beneficiai?
Labetalol is beneficial in a hyperadrenergic state following abrupt withdrawal of adrenergic blockers.
Class of dexmedetomidine?
It is a full alpha-2 agonist
Dexmedetomidine vs clonidine?
7-10 times more alpha 2 selective than clonidine.
Action of precedex ( in ICU or anesthesia)
Sedation
Analgesia
Action of precedex on sympathetic
Centrally mediated sympatholysis
CCB bind to voltage gated ion channels resulting in
A closed , inactive state
How does voltage gated ion channels work?
They receive a chemical signal from a neurotransmitter presynaptically and delivers that signal rapidly by converting it to a post-synaptic electrical signal . action
may be affected by ligands, ions, membrane potentials
Endocarditis is 3 to 8 times more prevalent in
MVP
MVP put at risk for
Dysrhythmias, stroke, MR, sudden death.
Heart murmurs from valve insufficiency occur when the blood goes backwards and
The ventricles are contracting
The valve is closed.