Apex- Cardiac Pathyophys Flashcards
Which surgical procedure presents the HIGHEST risk of CV morbidity and mortality for the patient with CAD?
A. ORIF femur fracture
B. VATS
C. Open AAA repair
D. Carotid endarterectomy
C.
High risk procedures = emergency surgery (esp in elderly), open aortic surgery, peripheral vascular surgery, long surgical procedures with significant volume shifts and/or blood loss
If a patient had a recent MI, the risk of re-infarction is greatest within ________ days/weeks of the orginal event
30 days
How long should elective surgery be delayed for after an MI?
4-6 weeks
5 patient risk factors that increase risk for cardiac event during surgery
which one confers the greatest risk of periop MI?
- ischemic heart disease
- CHF
- cerebrovascular disease
- DM
- Creat > 2mg/dL
unstable angina = greatest risk
unstable angina → new-onset angina (<2 months), increasings sx (intensity, freq, duration), duration exceeding 30 minutes, sx responding less to medical therapy
Risk of perioperative MI in the general population is ~ ____ %
0.3%
If the patient has ahd a previous MI, than the perioperative risk of reinfarction is:
- if > 6 months ago →
- if 3-6 months ago →
- if < 3 months ago →
- if > 6 months ago → 6 %
- if 3-6 months ago → 15%
- if < 3 months ago → 30%
remember as <3 months ago = 30%, then half it, and half it again
NYHA heart failure classification for someone with symptoms with less than normal activity but no symptoms at rest
3
compared to sx with normal activity + no sx at rest = 2
Which NYHA heart failure classification requires referral to a cardiologist prior to GA
Class 3 - symptoms with less than normal activity (none at rest)
or
Class 4 - symptoms with minimal activity or even at rest
T/F- NYHA heartfailure class 4 patients to undergo MAC anesthesia can proceed without a cardiac referrel as long as the preoperative evaluation reveals stable cardiac disease
True
When should a patient be referred to a cardiologist before surgery?
NYHA classification of 3 or 4 who is scheduled for high- or intermediate-risk surgery
factors that reduce myocardial o2 supply (4)
- tachycardia
- hypoxemia
- anemia
- left shift in oxyhemoglobin curve
Factors that increase myocardial o2 demand (7)
SNS stimulation : increased HR and BP
Increased preload/wall tension
Increased afterload
Increased contractility
Myocardial injury and infarction injure the sarcolemma. Disruption of the sarcolemma allows for what to happen?
intracellular proteins (CK-MB, troponin-I, tropinin-T) to enter systemic circulation
What lead is best for monitoring dysrhythmias?
Lead II
it also can identify inferior wall ischemia (II = inferior ischemia)
Most MIs occur within ______ hours after surgery
48
Treatment of intraoperative myocardial ischemia should focus on itnerventions that do what?
make the heart slower, smaller, and better perfused
Which leads are best for detecting LV ischemia intraoperatively?
AKA: ST changes
V3, V4, V5
*classic teaching says V5 is best (anterior axillary line 5th ICS)
*newer data says V3 & V4 may be superior to V5
*if need to choose- choose V4 - midclavicular line 5th ICS
The combination of what 3 leads has an ischemic detection rate of up to 96%?
II, V4, V5
Do most MI’s occur intraop or postop?
postop - within 48 hrs of surgery
Myocardial ischemia & advanced age
Curve A demonstrates a greater rise in pressure at a given volume → decreased compliance → myocardial ischemia and advanced age
Curve C demonstrates increased compliance → aortic insuffiency and dilated cardiomyopathy
If the patient has diastolic dysfunction, CVP and PAOP will (overestimate/underestimate ventricular filling pressures)
overestimate
pts with diastolic dysfuction require higher filling pressures to prime the ventricle
What describes the ventricular filling pressure that results from a given end-diastolic volume?
Diastolic compliance
Decreased diastolic compliance shifts the curve (up/down) and (left/right)
What does t his mean?
up and left
Theres a higher end diastolic PRESSURE for a given volume
Increased diastolic compliance shifts the curve (up/down) and (left/right)
what does this mean?
down and right
there is a LOWER end-diastolic PRESSURE for a given EDV
What do elevated filling pressures put patients at a higher risk for?
Pulmonary edema
What are 2 conditions that dilate the heart and cause increased diastolic compliance (lower pressure for a given volume)
Dilated cardiomyopathy
Chronic aortic insufficency
What are PAOP and CVP indirect measurements of?
Volume
Identify a compensatory mechanism in the patient with CHF:
A. decreased brain natriuretic peptide
B. Decreased LVEDP
C. Increased renal blood flow
D. Increased sympathetic tone
D. Increased sympathetic tone
To maintain BP, pts with CHF rely on elevated levels of circulating catecholamines (increased SNS tone)
*anesthetic techniques that reduce SNS tone can preceiptate CV collapse - ex) a standard propofol induction dose is not a good idea bc it decreases SNS tone while simultaneously reducing myocardial contractility. Propofol should be slowly titrated at a much lower dose
CHF reduces renal blood flow which is the primary mechanism that activates RAAS
Atrial dilation from CHF increases release of natriuretic peptides
Identify a compensatory mechanism in the patient with CHF:
A. decreased brain natriuretic peptide
B. Decreased LVEDP
C. Increased renal blood flow
D. Increased sympathetic tone
D. Increased sympathetic tone
To maintain BP, pts with CHF rely on elevated levels of circulating catecholamines (increased SNS tone)
*anesthetic techniques that reduce SNS tone can preceiptate CV collapse - ex) a standard propofol induction dose is not a good idea bc it decreases SNS tone while simultaneously reducing myocardial contractility. Propofol should be slowly titrated at a much lower dose
CHF reduces renal blood flow which is the primary mechanism that activates RAAS
Atrial dilation from CHF increases release of natriuretic peptides
Most common cause of right heart failure
left heart failure
3 ways to treat RV failure
- Reverse causes of increased PVR (hypoxia, hypothermia, hypercarbia, acidosis, high PEEP, nitrous oxide)
- Inotropes → milrinone, dobutamine
- Pulmonary vasodilators → inhaled nitric oxide or sildenafil (PDE-5 inhibitor)
Pathophysiolgoic complications r/t chronic systemic HTN include all of the following EXCEPT:
A. LVH
B. increased myocardial o2 concsumption
C. dysrhythmias
D. Decreased diastolic filling time
D. Decreased diastolic filling time
diastolic filling time is determined by the HR, not BP
Systemic HTN increases afterload. The LV must generate a higher amount of wall tension to open the aortic valve → to compensate for this increased afterload: heart undergoes concentric hypertrophy → increased MVO2 → thicker heart = reduced compliance = diastolic dysfunction (decreased lusitropy)
T/F- systemic HTN is almost always caused by an increased SVR
True
SBP &/OR DBP ranges for
Normal, Elevated, Stage 1, 2, and 3 HTN
Normal → <120 & <80
Elevated → 120-129 & <80
Stage 1 HTN → 130-139 or 80-89
Stage 2 HTN → > 140 or > 90
Stage 3 HTN → >180 and/or >120
Stage 3 HTN = hypertensive crisis
primary vs secondary HTN
primary → no identifiable cause (95%)
secondary → + identifiable cause (5%)
Normal cerebral autoregulation occurs at a CPP between what and what?
CPP 50-150
Why is it important to adequately hydrate the chronically hypertensive patient prior to anesthetic induction?
Bc hypertensive patients are volume contracted (even more so if they are on a diuretic)
→ agents that cause myocardial depression and vasodilation will unmask a volume contracted state and these patients will have an exaggerated hypotensive response to anesthetic induction
why shouldn’t a betablocker be started on the day of surgery in a patient who is normally not on a betablocker?
Studies have shown it increases the risk of hypotension, vradycardia, stroke, and death.
Why shouldnt peeps take their ACE/ARBs prior to surgery?
It can produce vasoplegia under anesthesia
*refractory hypotension
ACEi/ARB induced vasoplegia that is unresponsvie to conventional first-line therapies (vasopressors and fluids) should be treated with what? (3)
- vasopressin
- terlipressin
- methylene blue (nitric oxide antagonist)
How does methylene blue tx refractory hypotension?
it inhibits nitric oxide (substance released from the lining of the vessels that results in vasodilation)
@ what systolic/diastolic BP should elective surgery be delayed in favor of optimization?
SBP > 180
DBP > 110
Measuring the BP on the arm (or worse the leg) in the patient in the sitting position will (over/under)estimate the BP in the brain
overestimate (the brain BP is lower)
HTN crisis occurs wehn the BP exceeds what?
When is it deemed a hypertensive EMERGENCY?
180/120
when there is evidence of end-organ damage (otherwise its called HTN urgency)
CNS: encephalopathy, stroke, papilledema
Cardiac: CHF
Renal: HTN-induced acute renal dysfunction
What is the MOST common cause of secondary HTN?
A. PIH
B. Coarctation of the aorta
C. Renal Artery Stenosis
D. Cigarette Smoking
C. Renal artery stenosis
A narrowed renal artery (atherosclerosis or fibromuscular dysplasia) reduces renal blood flow. In attempt to increase GFR, the kidenys activate the RAAS system
What is the definitive treatment of renal artery stenosis?
What shouldn’t these patients be give if B/L stenosis and why
renal artery endarterectomy or nephrectomy
No ACE inhibitors bc they can significantly reduce GFR and preciptate renal failure in pts with B/L renal artery stenosis
Match the HTN drug it its drug class
Drugs: perindopril, terazosin, eprosartan, nisoldipine
perindopril → ACE
terazosin → alpha blocker
eprosartan → ARB
Nisoldipine → CCB
Drug that reduces afterload, preload, vs preload and afterload
hydralazine → afterload reduction
nitroglycerine → preload reduction
Sodium nitroprusside → preload and afterload reduction
What 3 things can be targeted to reduce blood pressure?
ANS → alpha/beta blockers
Myocardium and VSM → CCBs, arteriodilators, venodilators
Kidney → ACEi’s, ARBs, loop diuretics, thiazide diuretics, K sparing diuretics, aldosterone antagonists
suffix “-zosin”
drug class, how they reduce BP
what other 2 drugs fall in this class that dont end in zosin?
Alpha-1 antagonists
→decrease intravascular calcium → vasodilation → decreased SVR (afterload)
Phenoxybenzamine (long acting, non-competitive, selective); phentolamine (short acting, competitive, non-selective)
Selective B1 antagonists and how do they reduce BP
MABE AB
Metoprolol, Atenolol, Bisprolol, Esmolol, Acebutolol, Bextolol
→reduction in: inotropy, chronotropy, dromotropy, & renin release from juxtaglomelular aparatus
non-selective beta blockers
TPPNS
Timolol, Pindolol, Propanolol, Nadolol, Sotalol
*in addition to beta 1 effects, beta 2 blockade results in vasoconstriction in the muscle (not as profound decrease in BP)
Alpha-2 agonists - 2 most common and how do they reduce blood pressure
precedex and clonidine
-reduce sympathetic outflow
-“ipine” - what drug class, what do they target, and how do they reduce BP
CCBs - dihydropyridinines
→ target vasculature → decreases intravascular calcium → vasodilation → decreased SVR (Afterload)
What CCBs are the non-dihydropyridines , what classes are they, and how do they work?
Which produces more myocardial depression?
specific uses for each
Diltazem (Benzothiazepine)
Verapamil (Phenylalkamine)
→targets mycoardium > vessels
→ reduces: inotropy, chornotropy, dromotropy, SVR (afterload)
verapamil (dont use if on beta blockers > can result in CHB)
verapamil - angina, MI, SVT (afib/flutter)
diltazem - chronic HTN, arrhythmia protection (afib/flutter)
How do loop diuretics work?
3 examples
inhibit NA-K-2Cl transporter in the thick ascending loop of henle
→diuresis → reduced venous return (preload)
fureosemide, bumetanide, ethracrynic acid
4 Thiazide diuretics (mneumonic), how do they combat HTN
MICH
Metolazone, Indapamide, Chlorthialidone, HCTZ
inhibits the NA-Cl transporter in the DCT
→diuresis → reduced venous return (decreased preload)
K+ sparing diuretics vs Aldosterone antagonists
-examples of each, where do they work
K sparing = Triameterene & amloride
Aldosterone antagonists = Spironolactone
they inhibit K+ excretion and NA reabsorption by the principle cells in the collecting ducts
→ K sparing diruetics work indepdently of aldosterone
→ aldosteron antagonists also block aldosterone at mineralcorticoid receptors
A patient with a hx of CAD with an EF of 35% develops AFIB with RVR. Which is the BEST treatment for this patient
A. Verapamil
B. Diltaizem
C. Nifedipine
D. Nicardipine
B. Diltaizem
Rank the order in which the following CCBs impair contractility from most to least
→ nifedipine, verapamil, nicardipine, diltazem
Verapamil → nifedipine → diltazem → nicardipine
What is the only CCB proven to reduce the M&M from cerebral vasospasm?
Nimodipine
What are the 3 types of voltage-gated calcium channels; which ones do all clinically used CCBs bind to and what happens?
L type = long-lasting or slow channel
N type = neural
T type = transient
*CCBs bind to the alpha-1 subnit of the L-type calcium channel
→ this prevents calcium from entering the cardiac and VSM cells
Which CCB is useful as a coronary antispasmodic?
Nicardipine
MOA of clevidipine
Arterial vasodilator → reduces SVR without affecting preload
lipid emulsion (EDTA preservative)
How is clevidipine metabolized?
by tissue and plasma esterases
1/2 life = 1 minute (full recovery 5-15 mins after stopping gtt)
Identify the anesthetic considerations for constrictive pericarditis (select 2):
- kussmaul’s sign is usually present
- it is mot commonly caused by a virus
- afterload should be reduced
- bradycardia should be avoided
Kussmaul’s sign is usually present
Bradycardia should be avoided
→constrictive pericarditis limits the hearts ability to move within the pericardial sac → decreased myocardial compliance and limits diastolic filling
acute pericarditis (not constrictive) is usually caused by a virus
Kussmauls sign is a paradoxical rise in CVP and JVD during inspiration resulting from RV filling defect (impared RV compliance)
→ since stroke volume is reduced, the cardiac output is HR dependent ( avoid bradycardia)
→ BP = CO x SVR → if CO is limited, the BP must be maintained by SVR → DO NOT REDUCE AFTERLOAD
Identify the anesthetic considerations for constrictive pericarditis (select 2):
- kussmaul’s sign is usually present
- it is mot commonly caused by a virus
- afterload should be reduced
- bradycardia should be avoided
Kussmaul’s sign is usually present
Bradycardia should be avoided
→constrictive pericarditis limits the hearts ability to move within the pericardial sac → decreased myocardial compliance and limits diastolic filling
acute pericarditis (not constrictive) is usually caused by a virus
Kussmauls sign is a paradoxical rise in CVP and JVD during inspiration resulting from RV filling defect (impared RV compliance)
→ since stroke volume is reduced, the cardiac output is HR dependent ( avoid bradycardia)
→ BP = CO x SVR → if CO is limited, the BP must be maintained by SVR → DO NOT REDUCE AFTERLOAD
T/F- constrictive pericarditis is usually caused by a virus
False- Acute pericarditis is usually caused by a virus
3 conditions that affect the pericardium and limit the hearts ability to move within the pericardial sac
- acute pericarditis
- constrictive pericarditis
- cardaic tamponade
Acute vs constrictive pericarditis
Acute is usually caused by a viral infection/inflammation. It doesn’t reduce diastolic filling unless the inflammation leads to constrictive pericarditis or cardiac tamponade.
→constrictive pericarditis is caused by fibrosis or any condition where the pericardium becomes thicker. it leads to reduced diastrolic filling.
treatment for constrictive pericarditis
pericardiotomy
3 main anesthetic considerations for constrictive pericarditis
- avoid bradycardia → since SV is reduced, CO is dependent on HR (CO= HR x SV)
- preserve contractility
→ ketamine, etomidate, benzos, opioids, pancuronium
→ volatile agents with caution - maintain afterload
*Aggressive PPV can decrease venous return and CO
The pericardium is composed of ____ layers that are seperated by _______mls of clear fluid
2 layers:
Visceral layer → attached to myocardium
Parietal layer → anchored in the mediastinum
Seperated by 10-50mls of clear fluid
What is Kussmauls sign
& what does it indicate
an increase in CVP and JVD during inspiration
due to RV filling defect (impared RV complianc)
→constrictive pericarditis
What is pulsus paradoxus
& what is it indicative of?
Decreased SBP > 10mmHg during inspiration
indicative of impaired diastolic filling
What presents as ST elevation with normal enzymes
what else would be present
acute pericarditis
Acute CP with pleural component → increased CP with inspiration and postural change; releaved by leaning forward or supine
*Pericardial friction rub
*Fever
Treatment of acute pericarditis
usually resolves spontaneously
Drugs to relieve pain → salicylates, oral analgesics, corticosteroids
Why is it important to maintain spontaneous ventilation as long as possible for someone with constrictive pericarditis/tamponade
bc spontaneous respirations = negative pressure inside chest wall to draw in air → also helps blood flow more easily into the RA and supply preload
once positive pressure ventilation takes place- you lose that preload and CO
Is dressler’s syndrome associated with constrictive or acute pericarditis
acute
What are the 3 components of Becks triad
what do they indicate
Muffled heart tones, JVD, hypotension
→pericardial temponade occurs when the pericardium fills with fluid → this restricts the hearts movement and impairs its ability to function as a pump
*fluid accumulation in the pericardial sac → muffled heart tones
*decreased venous return to the heart → JVD
* decreased SV → hypotension
What is a pericardial effusion
accumulation of fluid inside the pericardial sac
it’s not an emergency and seldum requires intervention
Clinical presentation of cardiac tamponade (4):
- Becks triad:
→ muffled heart tones from fluid accumulation in the pericardial sac
→ JVD from decreased venous return to the right heart
→ hypotension from decreased stroke volume - Pulsus paradoxus
→ decrease in SBP > 10mmHg during inspiration d/t impaired diastolic filling - Kussmaul’s sign
→ paradoxical increase in CVP and JVD during inspiration d/t impaired RV compliance (impaired filling) - Reduced EKG voltage (from fluid in the pericardial sac impeding transmission of signals)
How do CVP, PAOP coincide with
CVP = right cardiac diastolic filling pressure?
PAOP = left cardiac disastolic filling pressure?
i think, idk maybe
Describe the pressure-volume loop of cardiac tamponade
Left shift → from decreased LV EDV
Narrower loop → from decreased stroke volume
Higher/steeper slope during ventricular filling → decreased ventricular compliance
What is this and why does it happen
Pulsus paradoxus → decrease in SBP by >10mmHg during inspiration
*negative intrathroacic presssure on inspriation → increased venous return to the RV → bowing of interventricular septum toward the LV → decreased SV → decreased CO → decreased SBP
A patient with blunt chest trauma presents for pericardiocentesis. He exhibits JVD and kussmaul’s sign. What is the BEST induction agent for this patient?
A. Propofol
B. Etomidate
C. Ketamine
D. Midazolam
C. Ketamine
*the patient with pericardial tampone relies on an elevated SNS tone to maintain BP. Most GAs cause myocardial depression and reduced afterload (both of which ontribute to CV collapse)
→local anesthesia is the preferrred technique for pericardiocentesis
if GA is required, ketamine is the best option as it activates the SNS which increases HR, contractility, and afterload
Surgical management of cardiac tamponade (2)
Pericardiocenteisis (needle aspiration) and pericardiostomy
Optimal anesthetic mangement for cardiac tamponade
Local anesthethesia to preserve hemodynamic stability
if GA required, use drugs that preserve myocardia function such as : ketamine, n20, benzos, and opioids
→maintain NSR, preload, afterload, , and contractiltiy
→ spontaneous ventilation is preverred over PPV
Pericardiocentesis vs Pericardiostomy
complications
Pericardiocentesis → needle is used to aspirate pericardial fluid
Pericardiostomy → surgical opening and drainage of the pericardium (subxiphoid, thoracoscopic, or thoracotomy)
PTX, re-accumulation of pericardial fluid, puncture of the coronary vessels or myocardium
A patient presents to the preop clinic with hx of infective endocarditis; which procedure puts this pt at the HIGHEST risk of an adverse outcome:
A. cystoscopy
B. Colonoscopy
C. Dental implant
D. Coronary stent placement
Dental implant
→pts at high risk for developing bacteremia after certain “dirty procedures” should receive antibiotic prophylaxis
What is infective endocarditis
a bacterial infection of the heart valves and endocardium
What patients should receive prophylaxis for infective endocarditis? (3)
Hx IE
Prosthetic heart valve
Congential heart defect
What non-cardiac procedurs are indications for prophylaxis for infective endocarditis (3)
- Dental procedures with gingival manipulation
- certain resp procedures
- biopsies of infected lesions
What cardiac procedures are NOT indications of prophylaxis for infective endocarditis? (3)
- MVR
- CABG
- Coronary stent placement
IV antibiotics for IE prophylaxis (4)
ACCC
Ampicillin
Cefazolin
Ceftriaxone
Clindamycin
What is infective endocardities usually caused by?
Bacteremia
bacteria in the bloodstream
What is infective endocardities usually caused by?
Bacteremia
bacteria in the bloodstream
T/F- unrepaired cardiac valve disease requires prophlyatic antibotics for IE
False
T/F- bronchospy with biopsy requires prophlyactic antibiotic of IE
True