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 stretch ventricle and ⇡ contractility/SV (Frank-Starling)
- 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 cardiac effects of all volatile agents:
- Dose-dependent ⇣ in contractility
- Dose-dependent ⇣ in SVR
- Dose-dependent ⇡ in CBF
- Sensitization of the 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 and consider low-end dosing of anticholinergic w/ reversal agent
EKG leads and what they evaluate:
- II, III, aVF: RCA ⇢ R atrium, R ventricle, SA node, AV node ⇢ inferior wall MI
- I, aVL: Circumflex ⇢ lateral L ventricle ⇢ lateral wall MI
- V3-V5: LAD ⇢ anterolateral L ventricle ⇢ 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:
- Maintain high preload; the heart needs the volume
- Decrease HR to ⇣ O₂ demand
- Decrease contractility to ⇣ O₂ demand
- Normal to high-normal SVR to counter the high ejection velocity and preserve coronary perfusion
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 and sympathomimetics (pancuronium) and 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 or 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
Maintenance drugs to avoid in IHSS patients:
Inotropes
Calcium agonists
Beta agonists (ephedrine, dopamine, dobutamine)
NTG/NTP (will ⇣ SVR)
Signs/symptoms of forward vs. backwards failure:
- Forward failure (think ⇣ CO, ⇣ end organ perfusion): fatigue, hypotension, oliguria, RAAS activation
- Backwards failure: ⇡ filling pressures, LV dilation, mitral regurgitation
Anesthetic/cardiovascular goals for DC 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 DC 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)
Maintenance drugs to use and avoid in DC patients:
- Treat tachycardia with esmolol (not at high doses though - loses selectivity, depresses myocardium)
- 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 is going to depend much more on HR than SV
- Normal to high-normal preload: 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, ⇡ SVR, ⇡ 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
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/cardiovascular 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 (lido, opioids, induction agent)
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
- 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, but make sure to keep fluid volume up to avoid ⇣ SVR
Anesthetic/cardiovascular 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
o 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 CHF
- Compensatory SNS ⇡ incl. anxiety, diaphoresis, resting tachycardia
- Cardiac dysrhythmias, esp. a-fib
- Angina d/t insufficient O₂ supply
Discuss regional anesthesia in aortic stenosis patients:
• Not a good choice; sympathectomy ⇣ SVR which leads to ⇣ venous return and ⇣ perfusion pressure and heart with AS is already susceptible to ischemia d/t ⇡ O₂ demands
Anesthetic/cardiovascular 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)
- Maintain high-normal HR, but not tachycardic
- Maintain SVR; need the pressure to perfuse and keep valve open as much as possible
Induction drugs to use/avoid in aortic stenosis patients:
- Avoid pre-medication - patients need SNS outflow
- Avoid high-dose opiates (bradycardia)
- Etomidate is drug of choice
- NDMR: Vec, roc, cis (no CV effects)
Maintenance drugs to use/avoid in aortic stenosis patients:
- N₂O + low dose VA; if LV dysfxn severe, consider N₂O + opioids
- Avoid halothane: SA node depression, can put pts in junctional rhythm
- Esmolol for tachycardia
- Lido for ventricular dysrhythmias
Pre-op assessment for aortic 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 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
- Maintain normal SVR and 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:
o NTP 0.5 - 10 μg/kg/min - drug of choice d/t short DoA
o NTG 5 - 200 μg/kg/min
o 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
