Oral Review: Cardiac Flashcards
What are some factors that influence the heart’s O₂ demand?
- HR
- SVR
- Filling pressures
- Preload and afterload
- Contractility
What are some factors that influence the heart’s O₂ supply?
- HR
- CO
- Coronary perfusion pressure (MAP - CVP)
- O₂ carrying capacity (Hgb)
- FiO2
What is the most important factor for supply and demand in IHD/CAD pts?
HR; affects both supply and demand
Compare and contrast stable, unstable, and prinzmetal angina:
-
Stable:
- at least 60 days no ∆ in frequency,
- duration or other factors;
- associated with a fixed narrowing (usually 75%+)
- relieved by rest, NTG
-
Unstable:
- becoming more frequent, longer, or more severe
- occuring at rest or with less exertion;
- associated with an unstable plaque/thrombosis;
- signals impending MI
-
Prinzmetal:
- coronary vasospastic disease
What is our fundamental goal for IHD/CAD pts?
Balancing O₂ supply with O₂ demand
Discuss regional anesthesia in IHD/CAD patients:
- Regional anesthsia is acceptable as long as we treat ⇣ in SBP to keep within 20% of baseline.
- Sympathectomy can actually help, but we need to make sure fluids counteract hypovolemia leading to hypotension
- Good drugs for this include ephedrine and phenylephrine
- Especially phenylephrine: no inotropy/chronotropy = does not affect O₂ demand at all
Discuss opioids’ effects on cardiac function:
- Cause dose-dependent bradycardia and vasodilation
- No independent ⇣ in CV function
- When used with N₂O or benzos
- cause ⇣ CO and ⇣ BP
Discuss induction in an IHD/CAD patient:
-
Blunt SNS outflow as much as possible prior to laryngoscopy,
- using lidocaine, fentanyl, and/or esmolol,
- and Keep it SHORT
Cardiovascular goals for IHD/CAD patients:
-
Avoid tachycardia!!
- Low-normal HR needed to ⇣ O₂ demand.
-
Maintain normal preload;
- preload needed to fill ventricle and maintain SV (Frank-Starling)
- ⇡ preload = increase demand
- ⇣ preload = decreased coronary profusion
-
Maintain normal afterload;
- afterload needed to maintain diastolic pressure and ⇡ O₂ supply to coronaries
-
Decrease contractility if LV function is normal;
- this will ⇣ O₂ demand.
Four hemodynamic effects of all volatile agents:
- Dose-dependent ⇣ in contractility
- Dose-dependent ⇣ in SVR
- Dose-dependent ⇡ in CBF
- May Sensitize heart to epinephrine
IA of choice in cardiac anesthsia is usually:
Isoflurane
Emergence and post-op considerations for IHD/CAD patients:
- Shivering and pain will ⇡ O₂ demand; minimize them
- Supplemental O₂ will ⇡ O₂ supply
-
Smooth emergence
- consider low-end dosing of anticholinergic w/ reversal agent
- lidocaine prior to extubation
- extubate deep if possible
EKG leads and what they evaluate:
-
II, III, aVF:
-
RCA ⇢ inferior wall MI
- R atrium, R ventricle,
- SA node, AV node
-
RCA ⇢ inferior wall MI
-
I, aVL:
- Circumflex ⇢ lateral wall MI
- lateral L ventricle
- Circumflex ⇢ lateral wall MI
-
V3-V5:
-
LAD ⇢ anterior wall MI
- ⇢ anterolateral L ventricle
-
LAD ⇢ anterior wall MI
Three factors that determine LV outflow obstruction in IHSS:
- Contractility
- Preload
- Afterload
What is our fundamental goal for IHSS patients?
- Decreasing the LV outflow tract obstruction
(which is worsened by ⇡ contractility and ⇣ preload/afterload)
Discuss regional anesthesia for IHSS patients:
- Okay to do
- but be cautious to offset ⇣ preload/afterload with good fluid management otherwise you can worsen the LV outflow tract obstruction
Anesthetic/cardiovascular goals for IHSS patients:
GOAL: minimize LV outflow obstruction
- Decrease HR = ⇣ O₂ demand
- High preload = the heart needs the volume
- Normal to high afterload = normal SVR to counter the high ejection velocity and preserve coronary perfusion
- Decrease contractility to ⇣ O₂ demand
Discuss induction in IHSS patients:
- Heavy premedication to ⇣ SNS outflow and strong SNS blunting before laryngoscopy
- Consider use of VAs and esmolol before intubation
- Etomidate is drug of choice
- Avoid sudden ⇣ in SVR
- i.e. from propofol, STP
-
AVOID
- ketamine
- sympathomimetics (pancuronium)
- histamine releasers (miva, atra)
Maintenance drugs to use in IHSS patients:
-
Volatiles:
- deep (1-1.5 MAC) of any of the drugs, just watch the SVR;
- Deepen VA for hypertension
- Lighten VA junctional rhythm
-
Opioids:
- do not use as sole anesthetic d/t ⇣ SVR without myocardial depression;
- use with VAs or benzos to produce myocardial depression without sigificant ⇣ SVR
-
Phenylephrine a good choice
- ⇡ SVR without inotropic/chronotropic effect
-
Fluids are huge
- hypotension usually = hypovolemia for these patients
- Use propranolol or esmolol
- for persistant tachycardia
(Treat hypotension first with fluids and then with phenylephrine!)
Maintenance drugs to avoid in IHSS patients:
- Inotropes
- Calcium agonists
- Beta agonists (ephedrine, dopamine, dobutamine)
- NTP (will ⇣ SVR)
- NTG (will ⇣ Preload)
Signs/symptoms of forward vs. backwards failure:
-
Forward failure
- think ⇣ CO, ⇣ end organ perfusion:
- fatigue
- hypotension
- oliguria
- RAAS activation
- think ⇣ CO, ⇣ end organ perfusion:
-
Backwards failure:
- ⇡ filling pressures
- LV dilation
- mitral regurgitation
Anesthetic/cardiovascular goals for Dialated Cardiomyopathy patients:
-
Normal to high-normal HR:
- CO is HR dependent… SV will be small
-
Normal to high-normal preload:
- if SVR ⇡ too much, pulm edema is a risk
-
Normal (NOT ⇡) afterload:
- don’t ⇣ SVR too much, though, or it will ⇣ preload too
-
Increase contractility:
- heart is weak and needs as much force as it can get
Discuss induction in Dialated Cardiomyopathy patients:
- Be careful with opioids + benzos as the combination can ⇣ myocardial contractility
- Etomidate is drug of choice
- Choose NMB with minimal CV side effects
- vec, roc, cisat
- Avoid sympathomimetics (ketamine, pancuronium)
- Whyyy???
Maintenance drugs to use and avoid in Dialated Cardiomyopathy patients:
- Treat tachycardia with esmolol
- Use filling pressures to guide fluids
- Treat hypotension with ephedrine or phenylephine (go slow on phenylephrine; will ⇡ SVR)
Four stages of pericardial disease:
- Dry stage / acute pericarditis
- Effusion stage
- Cardiac tamponade
- Absorption stage / constrictive pericarditis
Discuss regional anesthesia for pericardial disease patients:
- Not usually an option due to the emergent nature of the surgery and existing hypotension.
- Pericardiocentesis can be done under local anesthesia, however.
Anesthetic/cardiovascular goals for pericardial disease:
-
Normal to high-normal HR:
- AVOID bradycardia,
- CO will depend much more on HR than SV
-
Normal to high-normal preload:
- Give fluids!
- need the volume to make SV as large as possible
-
Maintain inotropy:
- can’t fill as well as it wants, but we can keep it squeezing
- Avoid myocardial depression
Discuss induction in patients with pericardial disease:
- No pre-op meds!
- Need as much SNS outflow as possible!
-
Ketamine is good - ⇡ contractility, ⇡ HR
- Might need low dose propofol + ketamine + LMA until the effusion is drained, before turning on VAs
- Pancuronium if you need an NMB, but that’s unlikely
- Keep in mind that PPV can cause hypotension in the presence of tamponade (decreased venous return)
- Keep in mind that once theeffusion is draind they are likely to become HYPERtensive!!! Be ready for it!
Pre-op evaluation for mitral stenosis:
- Exercise tolerance
- S/s of CHF
- Compensatory SNS ⇡ like anxiety, diaphoresis, resting tachycardia
- Cardiac dysrhymias like a-fib
- Angina from ⇣ O₂ supply
Discuss regional anethesia for mitral stenosis pts:
-
Not a good choice;
- they are pre-load dependent and need to maintain SVR.
- Will need good fluid management if necessary
Anesthetic/hemodynamic goals for mitral stenosis:
Slow - Tight - Full
-
Slow:
- AVOID tachycardia to allow for diastolic filling
-
Tight:
- maintain SVR to preserve diastolic pressure and coronary filling
-
Full:
- maintain preload to ensure enough volume for diastolic filling
(Avoid hypoxemia/hypoventilation to prevent pulm HTN and right heart failure)
Discuss induction in patients with mitral stenosis:
- Avoid drugs that ⇡ HR or abruptly ⇣ SVR:
- ketamine, pancuronium, and all histamine-releasing drugs (miva, atra)
- Be sure to blunt laryngoscopy reflexes
1. (lido, opioids, induction agent)
- Be sure to blunt laryngoscopy reflexes
Maintenance drugs to use and avoid in mitral stenosis patients:
- Low dose VAs titrated slowly upwards
- IV fluids and phenylephrine to counteract VA vasodilation
- Inotropes like dobutamine to ⇡ contractility if needed (less increase in HR)
- Avoid desflurane - can really ⇣ ⇣ SVR and ⇡ HR (reflexive) esp if rapid ⇡ in concentration
Pre-op evaluation for mitral regurg:
- Exercise tolerance
- S/s of CHF
- Compensatory SNS ⇡ incl. anxiety, diaphoresis, resting tachycardia
- Cardiac dysrhythmias, esp. a-fib
- Angina d/t insufficient O₂ supply
Discuss regional anesthesia for mitral regurg patients:
Okay to use, but make sure to keep fluid volume up to avoid ⇣ SVR
Anesthetic/hemodynamic goals for mitral regurg:
Fast - Full - Forward
-
Fast: keep HR high-normal (80-90bpm)
- CO is going to be very HR dependent for them
-
Full: keep preload high
- to fill the tank and ⇡ SV as much as possible
-
Forward: maintain low-normal SVR
- in order to promote forward flow of SV and minimize backwards flow
- V-wave will reflect regurgitant flow
- Minimize myocardial depression
Drugs to use and avoid in patients with mitral regurg:
USE
- NMB with stable CV profile or pancurionium which will ⇡ HR
- For HTN, use hydralazine - no HR effect, and will ⇣ afterload more than preload
-
Isoflurane is VA of choice d/t hemodynamic effects
- N₂O + low dose VA to minimize myocardial depression
- for severe dysfxn, opioid or TIVA technique
-
Inotropes if ⇡ contractility needed
- dobutamine, isoproterenol
AVOID
- high dose opioids (will ⇣ HR), beta blockers (will ⇣ HR)
Pre-op evaluation for aortic stenosis:
- Exercise tolerance
- S/s of AS
- Syncope, Angina, Dyspnea on exertion
- Cardiac dysrhythmias
Discuss regional anesthesia in aortic stenosis patients:
NOT A GOOD CHOICE
- sympathectomy ⇣ SVR which leads to ⇣ venous return and ⇣ perfusion pressure
- the heart with AS is already susceptible to ischemia d/t ⇡ O₂ demands
Anesthetic/hemodynamic goals for aortic stenosis:
Maintain HR, SVR, preload, and avoid ⇣ CO at all costs
-
Maintain NSR
- these pts absolutely need atrial kick for LVEDV (remember more volume = more force)
- AVOID junctional and a-fib (they will be hard to get back)
- AVOID tachycardia
- Maintain preload and afterload;
- Adequate SVR → need the pressure to perfuse coronaries (avoid sudden decreases)
- Maintain preload to maintain venous return and optimize LV filling
Induction drugs to use/avoid in aortic stenosis patients:
-
BP is HR dependent
- if they become bradycardic treat with atropine or glyco
- Etomidate = drug of choice
- Phenylephrine = if BP drops
- Opoids are gread because they will decrease the HR
- NDMR: Vec, roc, cis (no CV effects)
Maintenance drugs to use/avoid in aortic stenosis patients:
-
Anestheisa maintained with
- N2O + opioids
- or if they have significant LV dysfunction a High Opioid Technique
-
NMB - w/o CV side effects (Roc, Vec, Cis-atra)
- Bad Choice = Pancuronium - stimualtes Ganglion and increases HR
-
Hypotension:
- treat with an alpha agonist
- Phenylephrine (it DOES NOT increase HR)
-
Treat Junctional Rhythm/Bradicardia
- (Glycopyrolate, Atropine, Esmolol) →BP is HR dependent
- SVT - treat promptly with cardioversion
- Aortic Senosis has a propensity to develop ventricualar arrythmias
- ALWAYS have Lidocaine and Amioderone
- ALWAYS have a Defibrilator Availible
Discuss regional anesthesia in aortic regurg:
• Discouraged due to unpredictability of ⇣ SVR reponse
Anesthetic/cardiovascular goals for aortic regurg:
Maintain forward flow
-
High-normal HR;
- will keep CO up even if SV is small
-
Maintanin normal preload
- caution…too much = pulmonary edema
-
Maintain normal SVR
- avoid sudden ⇡ to promote forward flow and coronary perfusion
- Minimize myocardial depression
Induction drugs to use/avoid in aortic regurg patients:
- Etomidate is drug of choice
- Ketamine may be useful to provide ⇡ HR
- High opioid + pancuronium for long cases
Maintenance drugs to use/avoid in aortic regurg patients:
-
Isoflurane better for long cases
- (minimal cardiac depression, maintains CO, preserves baroreceptor reflex)
- Sevoflurane for shorter cases
- Opioid + benzo for severe LV dysfxn
- NTP intra-op for hypertension to keep SVR from getting too high
- Atropine for bradycardia (promptly)
Describe hypertensive crisis:
DBP is acutely > 130
-
Can be from:
- MH
- thyroid storm
- pheochromocytoma
- eclampsia, etc
-
Can result in:
- encephalopathy
- CHF
- SAH
- renal insufficiency
Treatment for hypertensive crisis:
-
SNP 0.5 - 10 μg/kg/min
- drug of choice d/t short DoA
- NTG 5 - 200 μg/kg/min
- Labetalol 40 - 80mg q10min
(⇣ DBP by 20% in first 2 hours then gradually to baseline over 24-48 hours)
Pre-op evaluation for HTN:
- Is it controlled well enough for surgery?
- Review medications and consider anesthetic implications
- Evaluate for evidence of end-organ damage
Induction drugs to use/avoid in HTN:
- Lidocaine, opioids, or VA to make sure patient is deep before laryngoscopy
- Consider 100-200mg esmolol prior to laryngoscopy
- AVOID ketamine
Maintenance drugs to use/avoid in HTN:
- Keep phenylephrine and ephedrine handy
- Use easily titratable VA (sevo/des)
- Balanced technique to keep VA concentration low
-
Intra-op hypertension: usually from pain
- ⇡ VA and use opioids or antihypertensives
-
Intra-op hypotension:
- ⇣ VA concentration, supplement fluids if needed, check rhythm, consider sympathomimetics
