Midterm Flashcards
Aortic annulus is attached to pulmonic annulus by
Tendon of conus
Aortic annulus connected to AV valves by
Central fibrous body
Compare thickness to LV to RV
RV 4-5mm
LV 8-15mm
Location of coronary sinus
Between AV orifice and valve of IVC (between LA/LV on posterior surface of the heart
Compare upper 1/3 of septum to lower 2/3
Upper 1/3 smooth endocardium
Lower 2/3 is trabeculae
Provides flow to anterior 2/3 of IVS, R and L bundle branches, papillary muscles of MV, anterolateral-lateral and apical LV
LAD
Provides flow to LA and posterior-lateral LV
circ
Provides flow to SA/AV nodes, RA, RV, posterior 1/3 of IVS
RCA
Coronary perfusion pressure and its components
CPP = DBP - LVEDP
Neo to raise DBP
Nitro to lower LVEDP
Portion of myocardium most affected by extravascular compression and higher LVEDP
Subendocardium
Highest O2 extraction
Key responses to CAD in coronary circulation
Collateral flow
Remodeling
Determinants of myocardial O2 supply
HR
PCWP
DBP
O2 sat, Hct
CAD
Determinants of myocardial O2 demand
HR
PCWP
SBP
CO
2 determinants of myocardial oxygen balance that decrease supply and increase demand
HR
PCWP
Distribution of SNS responsible for increasing chronotropy and inotropy
Increased SNS (T1-T4)
Cardiac accelerator fibers
Effect of increased PNS activation on chronotropy
SNS competes with PNSin medulla which decreases chronotropy and inotropy
PNS only has modest effect on inotropy (30%)
Abnormal accessory pathways between the atria and the ventricles may bypass the AV node and cause
Re-entry dysrhythmias
__________ assure rapid distribution of depolarization
Purkinje network of fibers
Basic contractile unit of myocardial
Sarcomere
Ion permeability of cardiac muscle
Relatively permeable to K+
Impermeable to Na and Ca
Effect of increasing preload on PV loop
Shift to right
SV increased
Effect of increasing afterload on PV loop
Narrow and taller
Lower SV, higher pressure
Higher EDV
Effect of decreasing contractility on PV loop
Shift to right
SV maintained at cost of pulmonary congestion
3 ways body compensates for heart failure
Salt and water retention
Vasoconstriction
SNS stimulation
CV and respiratory effects of valsalva maneuver
Decreased HR
Decreased contractility
Vasodilation
CV and respiratory effects of baroreceptor reflex
Decreased HR
Decreased contractility
Vasodilation
CV and respiratory effects of oculocardiac reflex
Bradycardia
Asystole
Dysrhythmias
Hypotension
CV and respiratory effects of celiac reflex
Bradycardia
Hypotension
APNEA
CV and respiratory effects of bainbridge refles
Increased HR
Decreased BP
Decreased SVR
Diuresis
CV and respiratory effects of Cushing reflex
SNS stimulation = HTN
CV and respiratory effects of chemoreceptor reflex
Increased respiratory drive
Increased BP
Determinants of BP
BP = CO X SVR
Determinants of CO
CO = HR X SV
SV dependent on
Preload
Contractility
Afterload
HR determined by (3)
(+) or (-) chronotropic effects from SNS, PNS, SA node
Determinants of SVR
SVR = Tone X Viscocity
Tone dependent on
Radius
Pressure gradient
Vessel length
Viscosity dependent on
COP and Hg
Hemodynamic effects of Alpha 1 receptors
Vasoconstricts
Hemodynamic effects of Alpha 2 receptors
Blocks output (vasodilation)
Hemodynamic effects of Beta 1 receptors
Increased HR and contractility
Hemodynamic effects of Beta 2 receptors
Vasodilates
Bronchodilation
Increased gluconeogenesis
Hemodynamic effects of dopamine receptors
Vary depending on dose
Hemodynamic effects of muscarinic receptors
Decrease HR
Activates salivary and sweat glands
Decrease vascular tone (much lesser degree)
How is NE removed from nerve ending
Diffusion out of cleft into circulation
Metabolized by COMT in cleft
Reuptake into neuron, broken down by MAO
Receptor and hemodynamic effect of dexmedetomidine
Alpha 2 agonist
Decrease BP and HR
Receptor and hemodynamic effect of carvedilol
Mixed alpha/beta antagonist
Decrease HR and BP
Receptor and hemodynamic effect of NE
Alpha 1 and 2 agonist
Beta 1 agonist
Increase HR, contractility, PVR
Vasoconstriction
Receptor and hemodynamic effect of epi
All Alpha and Beta agonist
Increase HR, contractility
Vasoconstriction
Gluconeogenesis
Bronchodilation
Receptor and hemodynamic effect of labetalol
Mixed Alpha 1, Beta1, Beta 2 antagonist
Ratio 6:1 alpha:beta
Vasodilation
Bradycardia
Bronchoconstriction
Receptor and hemodynamic effect of esmolol
Beta 1 antagonist
Bradycardia
4 mechanisms of adrenergic receptor activation
Direct binding
Promotion of NE release
Blockade of NE reuptake
Inhibition of NE inactivation
Catecholamines adrenergic agonists
Epi
NE
Isoproterenol
Dopamine
Dobutamine
Noncatecholamine adrenergic agonists
Ephedrine
Phenylephrine
Terbutaline
CV effects of beta 1 receptor activation
Increased HR, contractility, automaticity, conduction, renin release
cardiopulmonary and vascular effects of PDE-3 inhibitors
Inhibition of enzyme prevents cAMP breakdown and increasing intracellular concentration
Increased inotropy, chronotropy, dromotropic
Dopamine 1-5 mcg/kg/min
Induces natriuresis
Dopamine 5-10 mcg/kg/min
Beta 1 activation
Increased contractility and HR
Dopamine >10mcg/kg/min
Alpha 1
Increased density of receptors
Seen with chronic decrease in receptor stimulation
Up regulation
Decreased density of receptors
Caused by chronic increase in receptor stimulation
Down regulation
Mechanisms responsible for BP effects seen with propofol
Decreased SNS outflow
Direct vasodilation
Mechanisms responsible for BP effects seen with thiopental
Decrease in BP due to venous pooling
Decreased contractility due to decrease Ca availability
If absent or impaired baroreflex CO and BP fall dramatically due to uncompensated pooling and myocardial depression
Mechanisms responsible for BP effects seen with midazolam
Profound decrease in SVR when used with opioid
Less profound with diazepam
Mechanisms responsible for BP effects seen with etomidate
10-15% decrease in SVR will increase BP 19%
Mechanisms responsible for BP effects seen with ketamine
Increased PVR and SVR
3 benefits of using N20 in addition to other inhaled anesthetics
Hasten onset
Ultrashort duration
Decrease dose of other inhaled agent
Cardiac anesthesia dose of propofol
Hypnotic
0.2-1.5mg/kg
Cardiac anesthesia dose of thiopental
Hypnotic
0.5-4mg/kg
Cardiac anesthesia dose of etomidate
Hypnotic
0.1-0.3mg/kg
Cardiac anesthesia dose of fentanyl
Opioid
3-25mcg/kg
Cardiac anesthesia dose of Sufentanil
Opioid
0.5-2mcg/kg
Cardiac anesthesia dose of Remifentanil
Opioid
0.1-0.75 mcg/kg/min
Cardiac anesthesia dose of cisatracurium , Vecuronium, pancuronium
70-100mcg/kg
Cardiac anesthesia dose of succinylcholine
1-2 mg/kg
Primary mechanism thought to be responsible for CV effects of volatile anesthetics
Reduction in calcium influx through sarcolemma dm depression of Ca release from SR
Relationship between dose of volatiles on BP, SVR, HR, and CI
All decrease BP in dose dependent fashion
Due to decrease in SVR
CV decrease due to vasodilation and preload reduction
HR increase and compensatory so CI maintained
Volatile most associated with increased HR
Desflurane
Sevo can at > 1 MAC
Effects of modern volatile agents on conduction, contractility, dysrhythmia potential, baroreflexes, and ischemic heart
Depress contractility and BP
Prolong AV conduction and QT interval
Predispose to catecholamine induced dysrhythmia
Attenuate baroreflexes in dose dependent fashion
Effect of volatile on coronary blood flow
Decreased coronary vascular resistance but coronary blood flow also decreased due to effects on DBP
Volatile considered to be agent of choice for pt with cerebrovascular disease undergoing cardiac surgery
Isoflurane
Non anesthetic drugs considered to have a synergistic relationship with volatiles on hemodynamics
Synergistic with ACE
Less with beta blockers
Limitations interaction with CBD
How does N20 interact with volatiles to impact hemodynamics
Decreased CO and SV
Also decreased MAC requirements
How does fentanyl interact with volatiles to impact hemodynamics
Decreases MAC, SVR, HR
How does propofol interact with volatiles to impact hemodynamics
Dose related circulatory depression
Decreased CO and BP
How does dexmedetomidine interact with volatiles to impact hemodynamics
Modestly affects circulatory effects
Decreased HR and SVR
Circulatory effects of N20 and how affected by other anesthetic agents
Activates SNS = increased SVR
Increased CVP and arterial pressure
SNS response intact w/ other volatiles
When given with opioids augments cardiac depression
Effect of moderate to high dose opioids on hemodynamics
More disinfectant bradycardia and vasodilation
Possible mechanisms for hemodynamic effect of opioids
Influence of SNS outflow from SNS
Bradycardia due to direct stimulant effect on central vagal nuclei
Opioid considered to have most favorable effect on HR and BP for intubation and intraop BP control
Sufentanil
Effects of fentanyl sufentanil on epi and NE levels
NE level lower with sufentanil
Lower epi intraop with Demerol
Effect of CPB on drug absorption
Reduced oral or IM absorption
Effect of CPB on drug distribution
Decreased volume of distribution
Decreased pulmonary drug distribution- increased systemic drug levels
Effects of CPB on drug elimination
Decreased drug clearance
Decreased renal function
3 drug classes commonly used as anti-ischemic therapy in pt with CAD
Nitrates
Beta blockers
Calcium channel blockers
MOA of NTG causing vasodilation
Converted to nitric oxide in smooth muscle
Vasodilation
Enhances myocardial oxygen delivery and reduces demand
Start to see decrease in SVR with NTG at what dose
> 50 mcg/min
4 beneficial effects of NTG in pt with CAD
Decreased PCWP/LVEDP
Decreased wall tension
Decreased myocardial O2 demand
Decreased ischemia
Dose dependent effects of NTG on venous and arterial blood vessels
Larger doses = arterial vasodilation
How NTG better suited for pulmonary HTN than other more potent arterial vasodilators
Vasodilation of pulmonary arteries and veins more than systemic
Decreased RAP
Decreased PCWP
Decreased PAP
Unique effects of NTG on coronary artery flow
Potent coronary vasodilators
Smaller coronaries dilate more
Reverses or prevents vasospasm
How use of NTG improves CPP
CBP improves as PCWP decreases
Reduces subendocardial pressure
Improves collateral flow
In pt with CHF NTG effect on cardiac performance
Decreased mitral regurg and afterload
Increased CO
Effect of NTG on cardiac performance in pt with normal LV
Inadequate preload = decreased CO
Effect of NTG on cardiac performance in pt with ischemic heart disease
Decreased wall tension, O2 demand, ischemia
Improved cardiac function
Benefits of beta blockade in pt with ischemic heart disease
- decreased cardiac O2 consumption
- improved coronary flow and collateral flow
- prolonged diastole
- increased flow to ischemic area
- reduced mortality after MI
- improved oxygen dissociation
Dose of esmolol
5-20 mg
Half life 9.5 minutes
Dose of metoprolol
Bolus 1-5 mg
Half-life 3-6 minutes
Dose of labetalol
Bolus 2.5-5mg
Half-life 2-6 hours
3 mechanisms by which calcium blocking drugs reduce myocardial oxygen demand
Depress contractility
Decreased HR
Decreased afterload (SBP)
2 drugs with primary action on heart CBD
Diltiazem
Verapamil
Primary action on arterioles (2) CBD
Nicardipine
Nifedipine
First line anti-hypertensive drug for heart failure pt with HTN
ACE inhibitor
Angiotensin converting enzyme inhibitors
4 advantages of ACEI over conventional anti-hypertensives
Free of CNS effects
Free of myocardial depressant effects
Metabolic changes not seen
Rebound HTN not seen
2 hemodynamic concerns associated with ACEI and ARBs during general anesthesia
Renin response impaired
Diuretics worsen hypotension
Normal response to surgical stimulation may be attenuated
May cause LVH to regress (impair remodeling)
Hypotension upon induction
Dose of hydralazine
2.5-10 mg IV or IM
Slow onset - 10 minutes
Offset 4 hours
Why thiosulfate used with nitroprusside
Reacts with sulfur do now
Effectively detoxifies cyanide