Cardiac Flashcards
What is the goal of pre-op cardiac assessment?
What are the 5 steps?
- Goal: identify patients with heart disease who are at high risk for perioperative cardiac morbidity or mortality or those with modifiable conditions or risks
- Steps:
- urgency of surgery
- determine if active cardiac condition
- determine surgical risk
- assess functional capacity
- assess clinical predictors/markers
What are the clinical predictors of minor increased cardiovascular risk (7)
What is the chance of having an event?
- HTN
- abnormal ECG
- smoking
- increased age/male sex
- hypercholesterolemia
- rhythm other than sinus
- family history
- <1% chance of having an event
What are the clinical predictors for an intermediate increase in cardiovascular risk?
- Known CAD
- prior MI > 1 month and Q waves on ECG
- history of mild, stable angina
- compensated or previous LV failure/CHF
- diabetes
- chronic renal insufficiency
- Cr > 2.0 mg/dL
- Cerebrovascular disease
- stroke, TIA
What are the clinical predictors for a major cardiovascular risk?
- unstable coronary syndromes
- acute or recent MI <1 month
- unstable or severe angina
- decompensated CHF
- significant arrhythmias
- HB, afib (depending on how controlled the rate is), vtach
- Severe valvular disease
- mitral, aortic stenosis
What is the overall mortality risk of an acute MI after GA?
When is this risk increased?
0.3%
Incidence is increased in the patient undergoing intrathoracic or intra-abdominal surgery or surgery lasting longer than 3 hours.
What is the risk of mortality with history of prior MI?
> 6 months ago?
3-6 months ago?
within three months?
within 7 days?
If reinfarction occurs?
- > 6 months ago: risk is 6%
- 3-6 months ago: risk is 10%
- within 3 months: 30%
- within 7 days: postpone surgery
- If reinfarction occurs, the mortality rate is 50%
What is the higherst risk period after an MI?
What are the ACC/AHA guidelines?
- Highes risk period is within 30 days after an acute MI
- ACC/AHA guidelines recommend waiting at least 4-6 weeks before elective surgery
Which surgeries are high risk?
intermediate risk?
low risk?
- High:
- intraperitoneal
- intrathoracic
- aortic and other major vascular
- emergent major operations (esp in elderly)
- long procedures with large fluid shifts/loss
- Intermediate
- Carotid endarterectomy
- peripheral vascular surgery
- head and neck
- neurologic/ orthopedic
- endovascular aneurysm repair
- low
- endoscopic procedures
- superficial
- biopsies
- cataract
- breast surgery, GYN
What is the “gold standard” test for coronary anatomy?
Coronary angiography
What do you want to try to figure out from the history, physical, and work up?
- severity of cardiac disease
- progression of the disease
- what the patient’s functional limitations are
What are some questions you might want to ask a pt you suspect of having cardiac disease?
- Do you become short of breath when lying flat (orthopnea) or with exertion?
- Have you ever has a heart attack or CHF?
- Do you have angina or chest pain/tightness?
- what precipitates it?
- what are some associated symptoms?
- how frequent? duration?
- what relieves the pain?
- Do you have irregular heart beats or palpitations?
- pacemaker? ICD?
- heart murmor?
- Problems with BP or on any meds?
- PVD, TIA/CVA?
What are some more questions, not directly related to the heart that you would want to ask a cardiac patient?
- DM?
- renal insufficiency?
- high cholesterol?
- estrogen status? I.e. menopause- increased risk
- age and weight?
- fatigues?
- syncope?
- anemia?
- smoker? alcohol?
- illicit drug use?
How do you assess the pts functional capacity?
- Exercise tolerance
- if the pt has no lung disease, this is the most “striking” evidence of decreased cardiac reserve
- Duke activity status Index
- 1-4 METS: eating, dressing, walking around the house, dishwashing
- 4-10 METS: climbing stairs, walk in neighborhood, heavy housework, golf, bowl, dance
- >10: strenuous sports (swimming, tennis, running, football)
- Those unable to meet a 4 MET demad are considered higher risk
What is a MET?
- Metabolic equivalent of task
- 1 MET = 3.5 mg/kg/min of O2 being consumed
- 70 kg pt = 240 ml O2
- This is the same minimum O2 flow required for a closed circuit
What is Angina?
What are some other causes of Angina?
Stats about silent MIs
- Angina- sign of imbalance between myocardial oxygen supply vs demand
- Other causes:
- Aortic stenosis- may have angina despite normal coronaries
- Esophageal spasm- caused by heartburn can cause angina that is relieved by NTG
- Silent MIs
- approximately 80% of ischemic episodes in CAD pts occur without angina
- Approximately 10-15% of acute MIs are silent
What is prinzmetal’s angina?
- Vasospastic angina that occurs at rest
- 85% have a fixed proximal lesion in a major artery, 15% have just spasm
- seen in pts with other vasospastic diseases:
- migrains
- Raynaud’s
What do you need to know/do if your patient has a pacemaker and ICD?
- Indication for the pacemaker or ICD
- underlying rhythm and rate
- type of pacemaker
- demand- sends electrical pulses if HR is too slow
- fixed- constant frequency
- radiofrequency- can be hacked
- chamber paced vs chamber sensed
-
When was the last time the pacemaker was interrogated by CIED? -prefer within last 3 months
- note settings and battery life
- Evaluate effect of magnet
- Inactivate ICD tachyarrhythmia detection and put defibrillator pads on
- to avoid having the ICD pick up other electricity in OR as a dysrhythmia
What can inhibit pacemaker firing in the OR?
What is the magnet for?
What should you monitor?
- Electrocautery can have electromagnetic interference that can inhibit pacemaker firing
- Bipolar electrocautery is preferred; avoid monopolar
- Most pacemakers can be converted to a fixed rate (asynchronous mode) by placing a magnet over the pacemaker box
- must have a magnet immediately available
- Have external pacing available
- Monitor some form of blood flow
- pulse ok, A-line
Where should the grounding pads be?
As far from the pulse generator and leads as possible
What are you going to look for upon physical exam of a patient with heart disease?
- Overall appearance
- obesity
- SOB
- sternal incision, pacemaker box
- Heart
- sounds
- Murmors
- Neck
- JVD
- Carotid bruit
- Lungs
- sounds
- SOB, effort
- Vital signs- BP in both arms
- Extremeties
- peripheral edema
- pulses
- clubbing
- skin color
How do you assess the different heart sounds?
(pic)
What is Erb’s point?
Erb’s point is where you can hear S1 and S2 equally
What is considered hypertension?
When should it be treated?
- HTN is BP > 140/90
- Treat if SBP >160 and DBP >90
- Beta blockers may have protective benefit
If pt has long standing severe HTN or uncontrolled HTN, what might you need to do?
- May need to delay surgery to control BP
- need ECG and serum BUN/Cr
- if on diuretics, CHEM 7
- continue meds
- Anxiolytic may help
What are the 2014 ACC/AHA recommendations regarding Beta blocker therapy?
- Continue beta blocker therapy on pts who have been on chronic BB therapy
- discontinuation may increase perioperative CV morbidity
- Start BBs on high risk patients
- >1 day prior to surgery, preferrably 2-7 days
- can be harmful if started day of surgery
What is heart failure?
What can cause it?
When is it suspected
- Heart failure- abnormal contractility or abnormal relaxation of the heart muscle
- can be causd by HTN or Ischemic heart disease (IHD)
- Suspected with:
- orthopnea
- nocturnal coughing
- fatigue
- peripheral edema
- 3rd, 4th heart sounds
- resting tachycardia
- rales
- JVD
- ascites
- HF and LV dysfunction is high risk and elective surgery should be postponed
What kind of work up do you want to do for a patient with Heart failure?
What meds do you want to continue before surgery?
- ECG
- Chem 7, BUN/Cr
- BNP (normal = <100 pg/ml
- CXR if you suspect pulmonary edema
- ECHO to objectively measure LVEF
- Continue all medications except ACEs and ARBs
Which type of valvular abnormality poses the greatest risk?
What is the deal with diastolic murmors?
What if the pt has a prosthetic heart valve?
- Aortic stenosis- valve area <1 cm2
- if symptoms, postpone surgery
- Diastolic murmors are always pathologic and require further evaluation
- If pt has prosthetic heart valve
- may need to bridge anticoagulant therapy
- may need bacterial endocarditis prophylaxis
Which arrhythmias are associated with perioperative risk?
CAD?
When should you postpone surgery?
- SVT and ventricular arrhythmias are associated with perioperative risk
- LBBB is strongly associated with CAD
- if new, stress testing or consulatation is required
- Postpone surgery if:
- uncontrolled afib
- ventricular tachycardia
- new-onset atrial fibrillation
- symptomatic bradycardia
- high-grade or third degree HB
What medications are ppl with cardiac issues typically on?
- beta blockers
- statins
- aspirin
- ACEIs/ARBS
- CCB
- nitro for angina
- diuretics
- antiarrhymics
What anticoagulant medications might your patient be on and when should you have them stop taking them?
- Antiplatelet (ASA, Plavix)
- discontinue 7-10 days prior
- Anticoagulants (coumadin, LMWH)
- discontinue Coumadin 3-5 days prior
- discontinue LMWH 12 hours prior
- want INR <1.5
- may use heparin gtt as bridge therapy, stop 4 hours prior to surgery
- Fibrinolytics (TPA, Streptokinase, Urokinase)
- usually cannot discontinue
What can you see regarding the heart on a CXR?
Who should get one?
- NOT specific for IHD, but can see:
- cardiomegaly
- pulmonary vascular congestion/pulmonary edema (CHF)
- pleural effusions
- Order CXR pre-op if:
- pt is over 75 and is high risk
- History of CHF
- symptomatic cardiovascular disease
What are the different classes for determining who should get an EKG?
- Class I: Patient should get EKG
- if pt has one or more: IHD, hx of heart failure, cerebrovascular disease, DM, renal insufficiency
- And they are getting vascular surgery
- Class IIa: It is reasonable to get EKG if:
- pt has no clinical risk factors (above) but is getting a vascular surgical procedure
- Class IIb: EKG may be considered if:
- they have one or more risk factors (above) and are undergoing and intermediate-risk surgery
- Class III: Should NOT be performed b/c it is not helpful
- in pts who are asymptomatic and undergoing low-risk surgical procedures
What do you review a 12-lead EKG to look for?
- acute MI
- prior MI
- rhythm or conduction disturbances
- cardiomegaly or ventricular hypertrophy
- other EKG abnormalities; electrolyte imbalances
What are the EKG indicators of acute ischemia?
- ST segment elevation >/= 1 mm
- T wave inversion
- development of Q waves
- ST segment depression, flat or downslope of >/= 1 mm
- peaked T waves
What leeds do you use to see:
Right side inferior of the heart (RCA)
Right side posterior of the heart (RCA)
- Right inferior (RCA)
- II, III, AVF
- Right posterior (RCA)
- V1, V2, V3
What leeds do you use to see:
Left side anterior (LAD)
Left side antero-septal (LAD)
Left side lateral (LCA)
- Left side anterior (LAD)
- I, AVL, V1-V4
- Left Antero-septal (LAD)
- V1, V2, V3, V4
- Left Lateral (LCA)
- I, AVL, V5, V6
How does treadmill exercise stress testing work?
What are you looking for?
How is it interpreted?
- Stimulates sympathetic nervous system stimulation by increasing BP and HR and therefore increasing myocardial O2 demand and consumption
- Look for ischemia by ECG changes
- Interpretation based on:
- duration of exercise the patient can perform
- Max HR achieved
- time of onset of ST depression
- degree of ST depression
- time until resolution of ST segment
What is considered a positive treadmill stress test?
What is this indicative of?
- Positive stress test: EKG signs
- ST segment depression >2.5mm
- ST depression occurs early in test (w/in first 3 minutes)
- Serious ventricular arrhythmias
- prolonged duration of ST depression in post recovery period
- Non EKG:
- If increase in BP or HR occurs at the time of ST depression
- if hypotension occurs–this is an ominous sign
- Indicative of CAD
How is pharmacologic stress testing done?
- IV injection of gamma-emitting radiopharmaceutical (thallium) that permits the imaging of blood within the heart and lungs
- Dipyridamole or adenosine administered as a vasodilator to increase coronary blood flow
- If area of decreased perfusion (cold spot) occurs only during stress, that shows ischemia
- If cold spot is constant, that suggests old MI
- this is a fixed defect, MI is already scarred
- we prefer this because we can’t cause the problem?
- Look for ischemia by perfusion imaging, not ECG changes
When should you request stress testing?
- Active cardiac condition
- unstable coronary syndromes or severe angina
- recent MI
- decompensated HF
- significant arrhythmias
- Severe valvular disease
- 3 or more clinical risk factors AND poor functional capacity having vascular surgery
- Maybe if:
- 1-2 clinical risk factors and poor functional capacity having intermediate risk surgery, if it will change management
- 1-2 risk factors and good functional capacity having vascular surgery
What will and ECHO tell you?
- Measurement of dimensions of cardiac chambers and vessels and the thickness of myocardium
- chamber enlargement
- global ventricular systolic function: EF
- regional wall motion abnormalities
- valve structure and motion
- blood flow and measure gradients
- detect pericardial fluid
What do you look for an a stress ECHO and what is that predictive of?
- look for regional wall motion abnormalities under stress
- An abnormal result consists of new or worsening of existing regional wall motion abnormalities during an infusion of dobutamine (exercise/stress)
- Highly predictive of adverse cardiac events
When should you order a pre-op echo?
- Current or prior heart failure
- w/ worsening dyspnea or other changes
- to reassess LV dysfunction if they have previously documented LVD and it hasnt been reassessed for over a year
- Dyspnea of unknown origin
- clinically suspected valvular disease
- significant change in symptoms
What does Coronary angiography tell us?
- diffuseness of obstructive disease
- adequacy of any previous angioplasties or bypass grafts
- CA spasms
- LV pressures, volumes, and EF
- LV dysfunctions- akinesis, dyskinesis, low EF, high LVEDF
- Valve lumen and gradients
- pressure gradients across valves and shunts, as well as degree of regurgitation
- PA pressures
- CO and SVR
- Coronary angiography is the gold standard for cardiac anatomy and ppl undergoing cardiac surgery
When should a pt have a pre-op cath?
- Stable angina with left main CAD
- stable angina with 3-vessel disease
- stable angina 2-vessel disease with a significant proximal LAD lesion and EF <50% or ischemia on non-invasive stress testing
- high risk unstable angina or non-ST elevation MI
- Acute ST elevation MI
How long should an elective procedure wait after a previous coronary intervention (revascularization)?
- Balloon angioplast- wait at least two weeks
- Bare-metal stent- wait at least 30-45 days
- Drug-eluting stent- wait 365 days
What can an MRI tell us about the heart?
- Assess function and viability of myocardium
- highly sensitive in detecting infarctions using gadolinium (contrast)
- determine intracardiac tissue characterization
- Looking for clots or tumors
What are the different toolds used to assess cardiac risk?
- Gupta perioperative cardiac risk tool
- Revised cardiac risk index for pre-op risk (RCRI)
Which kind of cardiac conditions should get subacute bacterial endocarditis (SBE) prophylaxis?
- pts with high risk cardiac conditions associated with adverse outcomes from endocarditis
- prosthetic heart valves
- history of infective endocarditis
- congenital heart disease
- unrepaired cyanotic
- if repaired with prosthetic material and within 6 months of repair
- if repaired but still has residual defects
- cardiac transplant
If pts are high risk for SBE, which procedures do they need prophylactic antibiotics for?
- all dental procedures that manipulate gingival tissue or perforation of oral mucosa
- invasive respiratory tract procedures
- tonsillectomy, adenoids, abscess drainage, lung biopsy
- procedures involving infection of GI/GU tract, skin/musculoskeletal
- not recommended in routine GI/GU
- hepatobiliary procedures
- cardiac surgery
What are the standard SBE prophylaxis antibiotics and when are they administered?
- given within 30-60 minutes before procedure or up to 2 hours after if missed before
- medications:
- ampicillin 2 gm (50 mg/kg peds)
- Cefazolin 1 gm (50 mg/kg peds
- Ceftriaxone 1 gm (50 mg/kg peds)
- If PCN allergic, Clindamycin 600 mg )20 mg/kg peds)
