Friday, July 27, 2012

Advanced 1: CARDIOVACULAR ANESTHESIA


1.     CARDIOVASCULAR ANESTHESIA FOR NON-CARDIAC SURGERY[WU1]         M&M 19, 20
2.     8 STEPS TO OPTIMIZING PREOPERATIVE OUTCOMES

a.     Assess patients clinical findings
b.    Evaluation of functional status
c.     Consider the patient’s surgery specific risks
d.    Decide if further non-invasive evaluation is needed
e.     Decide when to recommend invasive evaluations
f.     Optimize medical therapy
g.    Perform appropriate preoperative surveillance
h.     Design maximal long-term therapy

3.     ASSESSING CLINICAL FEATURES (STEP 1)
a.     H & P
b.    High risk status includes:

                                          i.    Recent MI[WU2] 
                                         ii.    Decompensated heart failure
                                        iii.    Unstable angina
                                        iv.    Symptomatic arrhythmias
                                         v.    Symptomatic valvualr disease

c.     Stable conditions that are affected with surgical stress.
                                          i.    Stable angina
                                         ii.    Distant MI
                                        iii.    Prior HF
                                        iv.    Moderate valve disease
d.    Identify serious co-morbidity

                                          i.    Diabetes
                                         ii.    Stroke
                                        iii.    Renal insufficiency
                                        iv.    Pulmonary disease
4.     EVALUATING FUNCTIONAL STATUS (STEP 2)
a.     Assess functional capacity

                                          i.    Exercise tolerance
                                         ii.    MET – Metabolic Equivolence Test (activity level)


                                        iii.   

5.     SURGERY-SPECIFIC RISK FACTORS (STEP 3)

a.     High risk (reported cardiac risk* ≥5%)

b.        Emergency major operations, particularly in the elderly
c.         Aortic, major vascular, and peripheral vascular surgery
d.        Extensive operations with large volume shifts/and or blood loss[WU3] 
e.     Intermediate risk (reported cardiac risk ≥1%, <5% )

f.         Intraperitoneal and intrathoracic
g.        Carotid endarterectomy
h.         Head and neck surgery
i.          Orthopedic surgery
j.          Prostate surgery

k.     Low risk (reported cardiac risk <1%)
l.          Endoscopic procedures
m.       Superficial biopsy
n.         Cataract surgery
o.        Breast surgery

6.     PREOPERATIVE INVASIVE VS. NON-INVASIVE TESTING (STEP 4)

a.     Patients at low risks with steps 1-3 generally do not require additional evaluation.
b.    High risk patients may benefit
c.     Patients with more than 3 clinical risk factors and extensive myocardial ischemia on preop stress test may have a high risk of complications, and require beta therapy or invasive evaluation[WU4] .

d.    EKG EVALUATION

                                          i.    Greater than 1mm ST segment elevation in standard leads, and 2mm elevation in precordial leads.
                                         ii.    T wave inversion in leads I, II, V3-V6.
                                        iii.    Lead  II
                                        iv.    Lead V5

                                         v.    Preop:

1.     ST segment represents phase II of the cardiac action potential (slow repolarization)
2.     Signs of ischemia

a.     II, III, Avf = Right coronary
b.    I, Avr = circumflex
c.     V3-V5 = L anterior descending

3.     Arrhythmias
4.     Electrolyte disturbances
5.     Hypertrophy

                                        vi.    EKG- ST segment >1mm during angina confirms an MI.

e.     EXERCISE STRESS TEST

                                          i.    Used to evaluate ventricular function and prognosis.
                                         ii.    Some conditions do not permit an EST.

1.     PVD
2.     Pacemakers
3.     Severe aortic stenosis
4.     Lung disease

                                        iii.    Criteria for abnormalities:

1.     1mm ST segment elevation or depression within 4 minutes of exercising.
2.     The prognosis is poor if the ST segment abnormality is associated with angina, or a decrease in systolic blood pressure[WU7] .
3.     More cost effective.

f.     NON-INVASIVE IMAGES

                                          i.    Done when exercising isn’t possible[WU8] .
                                         ii.    The heart is induced with adenosine or persantine in order to produce vasodilation, or doputamine to raise the heart rate to exercise levels
                                        iii.    The patient is monitored for a change in EKG, and a radionucleotide  tracer is placed to check for myocardial function.
                                        iv.    ECHOCARDIOGRAM
1.     Wall stress is elevated after stressing the heart with dobutamine or pacing.
2.     Contrast dye can be given to enhance the images.
3.     You will see a decrease in wall motion abnormality with ischemia[WU9] .

                                         v.    TRANS-ESOPHAGEAL ECHO

1.     TEE is 2 dimensional tool used to measure contractility.
2.     Able to see ventricular as well as valve activity in real time
3.     Uses:

a.     Measuring stenotic and regurgitant lesions
b.    Hypokinesis, dyskinesis, or akinesis
c.     Contractility
d.    Volume status
e.     Ventricular dysfunction

4.     Gold standard for eval of cardiac patient; preferred over PAC intraop

g.    INVASIVE MONITORING (STEP 5) - CATH

                                          i.    Indicated when:

1.     Presence of residual ischemia after MI
2.     Unstable angina

                                         ii.    Stent placement prior to surgery
1.     Risks of thrombosis and bleeding post-op.
                                        iii.    AHA/ACC recommends waiting at least 2-4 weeks after stent for non-cardiac surgery

7.     OPTIMIZING THERAPY (STEP 6)
a.     Most patients with a history of angina will be on beta blockers, calcium channel blockers, aspirin
b.    Prior MI patients maybe on asa, beta blockers, and statins[WU10] 
c.     Heart failure patients may be on ACE inhibitors, and beta blockers.
d.    Smokers- are encourage to stop smoking.

8.     PREOPERATIVE SURVEILLANCE (STEP 7)
a.     EKG- base line, immediately after surgery and 2 days post-op.
b.    Bio markers such as CK MB maybe elevated immediately post-op. Watch for increases in those numbers.
c.     New EKG abnormalities.
d.    Patients who develop ST segment changes should be considered for cardiac catheterization.

9.     MAXIMAL LONG-TERM THERAPY (STEP 8)

a.     Evaluation before and after non-cardiac surgery can be used to optimize a patients condition, and modify the risks.
b.    Patients with history of repetitive post-op complications are at greater risk for long standing issue.
10.  ANESTHETIC MANAGEMENT OF MYOCARDIAL INFARCTION AND HYPERTENSION
11.  CORONARY ARTERY DISEASE
a.     Affects an estimated 10 million people in the US
b.    5-10% of the patients undergoing  anesthesia have heart disease.
c.     Careful evaluation of the patient can help reduce the M&M associated with cardiac patients undergoing non-cardiac surgery.

12.  PREOPERATIVE ASSESSMENT
a.     Determine the severity, progression and functional limitations.
b.    Determine if the are in high risk or low risk group.
c.     If a patient can climb three flights of steps they are considered to have good conditioning.
13.  COMPLICATIONS ASSOCIATED WITH MI
a.    Arrythmias
b.    Pericarditis
c.    Mitral regirgitation
d.    Ventricular Septal rupture
e.    Congestive Heart

f.     ARRYTHMIAS

                                          i.    Are common complications post MI

                                        ii.    V-fib

1.     Occurs in 3-5% of the population.
2.     Usually occurs within the first 4hrs
3.     Rx: Rapid defibrillation 200-300j

a.     Lidocaine 1-1.5 mg/kg
b.    Amiodarone  300 mg in 20-30cc D5W  loading (arrest), 150 mg in a 100cc bag of D5W given over 10 minutes (Loading infusion), 360 mg over 6H.
c.     Beta Blockers decreases incidence of V-fib very early on.
                                       iii.    V-tach[WU11] 

1.     Rx. Symptomatic V-tach with defibrillation
2.     Asymptomatic V-tach with Lidociane

                                       iv.    A-fib

1.     Most common artial arrythmia
2.     Occurs in 10% of the population
3.     Rx: Symptomatic is Rx with Cardioversion
4.     asymptomatic with B-blockers, Ca channel blockers

                                         v.    Brady-dysrrthmias.

1.     Common post IWMI (inferior wall MI)
2.     May reflect parasympathetic activity or acute ischemia of the SA or AV node.
3.     Rx:
a.     Atropine or pacer if needed.
b.    2nd and 3rd degree heart block occurs in approximately 30% of IWMI.
g.    PERICARDITIS

                                          i.    A common complication of acute MI and can be confused with angina.
                                         ii.    Unlike angina pericarditis will pain will change with changes in position, and upon taking a deep breath.
                                        iii.    Pericardial friction rub may be present.
                                        iv.    May see diffuse ST or T wave changes.

1.     Rx; aimed at relief of chest pain
2.     ASA, indomethacin and  corticosteroids.

                                         v.    Dressler’s syndrome: Is a delayed form of pericarditis that occurs weeks to several months after an MI.

h.     MITRAL REGURGITATION

                                          i.    Can be seen due to ischemic injury of the papillary muscles and or ventricular muscles[WU12] .
                                        ii.    Severe MR occurs 10 times more likely post IWMI.
                                        iii.    Severe acute MR results in pulmonary edema and heart failure.
                                        iv.    Total papillary muscles rupture results in death within 24 hours.
                                         v.    Rx: Decrease afterload, Nipride, or balloon pump until surgery.

i.      VENTRICULAR SEPTAL RUPTURE
                                          i.    Mortality rate is 20%
                                         ii.    Requires emergency surgery if hemodynamically unstable.
                                        iii.    Seen with AWMI
                                        iv.    Dx: holosystolic murmur
                                         v.    Place on balloon pump as soon as diagnosed.
j.      CONGESTIVE HEART FAILURE AND CARDIOGENIC SHOCK
                                          i.    Most acute MI patients will have some degree of heart failure.
                                         ii.    Cardiogenic shock: is an advanced form of heart failure in which cardiac out put is not sufficient to maintain perfusion of vital organs.
                                        iii.    Cardiogenic shock is seen in 40% of left ventricular MI.
                                        iv.    Rx:
                                         v.    Norepinephrine (4mg/1000cc D5W)- 2-4mcg/min
1.     α¹ & α²

                                        vi.    Vasopressin- 0.01-0.04 U/min

                                       vii.    Dopamine- 0.5-2.0mcg/kg/min (Dopa)
1.     2-10mcg/kg/mi (Dopa/Beta)
2.     10-20mcg/kg/min (Alpha)

                                      viii.    Dobutamine-2.5-15mcg/kg/min
1.     Beta 1 agonist

                                        ix.    If Bp is stable administration of nitro can be given to decrease LV preload and after load.

14.  RIGHT VENTRICULAR INFARCTION
a.     Occurs in about 1/3rd of patients with acute inferior wall left ventricular MI
b.    An isolated acute inferior wall MI to the right ventricle is very unusual.
c.     Dx:
                                          i.    clinical triad; hypotension, jugular venous distention and clear lung fields. Kussmaul’s sign (JVD with inspiration) can be seen.
d.    1/3rd of patients with right ventricular MI will develop A-fib.
e.     50% of the patients' may develop H.B
f.     Dx:

                                          i.    Recognition of right v.s left ventricular MI.
1.     V4 right on EKG. Placed under nipple of right side[WU13] .
2.     ST elevation >1mm on V4 right, St elevation >1mm on V1.

                                         ii.    Treatment of left ventricular MI in the face of right ventricular MI can worsen the condition.
                                        iii.    Diuretics and vasodilators are undesirable.

g.    RX:

                                          i.    Av sequential pacing
                                         ii.    Restore intravascular volume
                                        iii.    Administration of positive inotrope.


                                        iv.   

15.  CEREBRAL VASCULAR ACCIDENT (CVA)
a.     May be seen most commonly after an MI of the anterior wall and the apex of the left ventricle.
b.    Thrombus formation can be seen in 1/3rd of the patients.
c.     DX: Echo
d.    RX: Anticoagulants

16.  INTRAOPERATIVE MANAGEMENT OF PT WITH ISCHEMIC HEART DISEASE: Induction, Maintenance, Emergence

a.     GOAL OF ANESTHETIC MANAGEMENT
                                          i.    Goal is to prevent ischemia by:

1.     Increasing myocardial O2 supply
2.     Decrease myocardial O2 demand
3.     Monitor arrythmias and treatment if it develops

                                         ii.    Events that increase risks are:
1.     Tachycardia, hypertension, increased SNS response, hypoxemia and hypotension[WU14] .
2.     Standard is to keep HR and BP at 20% of baseline.

b.    INTRAOPERATIVE EVENTS THAT EFFECT O2 SUPPLY/DEMAND

                                          i.    Increased O2 requirements
1.     Increased  SNS
2.     Tachycardia
3.     Hypertension
4.     Increased contractility
5.     Increased after load

                                         ii.    Decreased O2 delivery

1.     Tachycardia
2.     Diastolic hypotension
3.     Hypocapnea
4.     Decreased O2
c.     ANESTHETIC INDUCTION IN THE PRESENCE OF PREVIOUS MI

                                          i.    Ketamine is not a good choice[WU15] .
                                         ii.    MR facilitates intubation
                                        iii.    Keep intubations at no greater than 15secs.
                                        iv.    Fentanyl 1-3mcg/kg
                                         v.    Nitro 0.25-1.0mcg/kg/min
                                        vi.    Laryngeal tracheal lidocaine (LTA)
                                       vii.    NGT/OGT[WU16] 

d.    PHYSIOLOGIC RESPONSES DURING INDUCTION
                                          i.    Tachycardia: Hr > 110

1.     Esmolol 100-200mcg/kg prior to DL[WU17] 
2.     or Metoprolol 2-5mg[WU18] 

                                         ii.    Hypertension:
1.     Nipride – 1-2mcg/kg 15s before DL
2.     Nitroglycerin (better choice for MI with normal BP) 10-20mcg/min

                                        iii.    Hypotension:

2.     Fluids- Takes time to [WU20] work.

e.     MAINTENANCE
                                          i.    Normal LV function

1.     Inhalationals are acceptable for Rx of HTN.
2.     Opioid/fentanyl technique + inhalationals
                                         ii.    Abnormal LVF[WU21] 

1.     Use short acting opioids over volatile anesthetics
2.     With severe disease you can use high dose opioids + nitrous
3.     Consider regional technique
4.     Select MR with limited CV effects

f.     CHOICES OF MUSCLE RELAXANT

                                          i.    Chose MR with limited side effects

1.     Vec
2.     Roc
3.     Cis

                                         ii.    Histamine release MR

1.     Atracurium à avoid

                                        iii.    Increase in HR

1.     Pancuronium

                                        iv.    Reversals
1.     Glyco has less effects than atropine[WU22] 

g.    SHIVERING AFFECTS ON THE HEART

                                          i.    Increases myocardial O2 demand- 500%
                                         ii.    Loss of body temperature in the OR is common, and in the post op period.
                                        iii.    Ways to increase body temp:

1.     Warmed fluids
2.     Inspired O2
3.     Warming blanket
4.     Increase room temp[WU23] 

17.  MANAGEMENT OF PT WITH ESSENTIAL HYPERTENSION

a.     PREOPERATIVE EVAL

                                          i.    Goal:

1.     Aimed at determining adequacy of blood pressure control, and hypertensive drug therapy.
2.     Drug therapy should continue preoperatively and should continue in the perioperative period.
3.     There is no evidence of postop complications increasing in the patient with hypertension, however, preop HTN may increase incidence of postop MI.

                                         ii.    If a hypertensive patients exhibit signs of end organ damage then elective surgery needs to be post-poned.
                                        iii.    White coat syndrome
                                        iv.    Evaluate end organ damage; heart failure, LV hypertrophy, CVA etc.
                                         v.    Evaluate drug therapy: Many antihypertensive drugs will affect the autonomic nervous system. This will manifest it’s self as orthostatic hypotension.
                                        vi.    Rebound hypertension may occur with certain drugs such as Beta blockers, and clonidine.
                                       vii.    During anesthesia you may see exaggerated responses to blood loss, positive pressure ventilation or sudden changes in body position.

b.    INDUCTION OF ANESTHESIA

                                          i.    Rapid acting intravenous agents- can cause a dramatic decrease in Bp due to peripheral vasodilation and decreased intravascular volume. (propofol)
                                         ii.    Intubation
                                        iii.    Keep DL < 15sec.
                                        iv.    Be cautious after induction[WU24] 

c.     MAINTENANCE OF ANESTHESIA WITH HTN

                                          i.    Volatile anesthetics and nitrous allows for rapid changes in depth in response to changes in BP.
                                         ii.    Opioids and nitrous
                                        iii.    There is no evidence to show one MR is better than the other[WU25] .
                                         v.    Treat the underlying cause.

1.     Volume= replace with volume.
2.     Anesthetic depth=increase anesthesia

d.    MONITORS

                                          i.    Depends on the type of surgery

1.     EKG
2.     A-line[WU27] 
3.     PA Catheter[WU28] 

                                         ii.    Regional anesthesia

1.     Take caution for hypotension
2.     Vasodilation may mask decrease in volume status[WU29] .

e.     POSTOPERATIVE MANAGEMENT

                                          i.    Episodes of hypertension are common postop.
                                         ii.    Treat with peripheral vasodilators

1.     Hydralizine 5-10mg Q 10-20 minutes
2.     Labetolol 0.1-0.5mg/kg
3.     Nipride infusion- 0.5-8mcg/kg/min, not to exceed 10mcg/kg/min for more than 10 minutes.

19.  DISORDERS OF THE CONDUCTION SYSTEM

a.     Review of EKG
b.    What are the basic areas to look at on EKG?

                                          i.    HR- 60-80
                                         ii.    P waves- Atrial depolarization. Up right in lead II, III, AVF
                                        iii.    PR interval- represents electrical signal from SA-AV node. Normally 0.12-20s
                                        iv.    QRS complex- Ventricular depolarization. Normal 0.04-0.12
                                         v.    Ventricular rate
                                        vi.    Any early beats, pauses after the QRS

c.     CLASSIFICATION OF CONDUCTION ABNORMALITIES

                                          i.    Are classified based on where the block is located in respect to the AV node.
                                         ii.    Blockage above the AV node- are usually benign and transient.
                                        iii.    Blockage below the AV node- tend to be progressive and permanent.

d.    HEART BLOCK

                                          i.    What is heart block?
1.     Impairment of the conduction system in sending signals from the SA-AV node.

                                         ii.    What are the types of heart block?

1.     First degree
2.     Second degree
3.     Third degree
4.     RBBB
5.     LBBB

e.     CLASSIFICATION OF HEART BLOCK
1.     First degree heart block.
a.     Electrical impulses move slowly from the SA to the AV node.
b.    EKG shows a PR interval of > 0.20sec, HR and the heart itself is normal.

2.     Seen in:

a.     Patients on digoxin, healthy athletes

3.     Treatment?

a.     None
b.    Treatment of first degree heart block is usually not an issue in anesthesia.
c.     Monitoring of the  condition to make sure it doesn’t progress to second degree type I.

                                        iii.    SECOND DEGREE

1.     SECOND DEGREE TYPE 1 (WENCKEBACH)

 
a.     Second degree type I (Mobitz type I)
b.    Some signals don’t reach the ventricle dropping some beats.
c.     Wenckebach
                                                                               i.    Electrical signals are delayed more and more with each beat until one beat is skipped.
d.    The conducted beat will have a short PR interval.
e.     S/S
                                                                                          i.    usually dizziness

f.     Seen in:

                                                                                          i.    Patients with an inferior wall MI.
                                                                                         ii.    Self limiting, and usually doesn’t require treatment.

3.     SECOND DEGREE TYPE 2
a.     Mobitz type II

                                                                                          i.    less common, but more serious.
                                                                                         ii.    The electrical signal cannot reach the ventricle and the patient may have an abnormally slow HR.
                                                                                        iii.    Excitation intermittently fails to pass through the AV node, or Bundle of His.

b.    These patients may require a temporary pacemaker[WU30] .
                                        iv.    THIRD DEGREE

 
1.     The hearts electrical signal doesn’t pass from the SA to the AV node (AV node dissociation).
2.     Independent ventricular pacemaker takes place.
3.     There is no relationship between the p waves and QRS.
4.     The heart contracts but with less force.

5.     Seen in:

a.     Pt’s with heart disease
b.    Drug toxicity- digoxin
c.     Congenital
d.    Post MI
e.     After heart surgery[WU31] 
f.     Surgical stimulation
g.    Stop, give atropine. Or glyco

6.     TREATMENT OF THIRD DEGREE

a.     Temporary pacer[WU32] 
b.    Isoproteranol: Potent B1, B2 agonist

                                                                                          i.    Run at 0.5 - 5 mg/min
c.     Permanent pacemaker

                                                                                          i.    Temporary external pacer
                                                                                         ii.    temporary transvenous pacer

d.    If due to surgical stimulation

                                                                                          i.    Have surgeon stop temporarily
                                                                                         ii.    Give atropine for bradycardia

                                        vi.    BUNDLE BRANCH BLOCK
1.     Characteristics-

a.     Widened QRS
b.    PR interval will be normal

2.     With BBB there is a delay in the depolarization of part of the ventricle by the right or left bundle branches.

3.     RIGHT BBB
  

b.    May indicate a problem with the right side of the heart, but a RBBB with normal axis and QRS duration may be normal.
c.     Tall R prime[WU33]  in V1
d.    QRS duration 0.12s or greater.
e.     Prominent S wave in the lateral leads.

5.     LEFT BBB

a.     LBBB- This often indicates heart disease.
b.    A tall notched R wave can be seen on the lateral leads (RR prime[WU34]  wave)
c.     There is usually a notched QS complex in V1 and V2[WU35] 

f.     SICK SINUS SYNDROME

                                          i.    Classified as Bradycardia with episodes of SVT.
                                         ii.    Can be due to degenerative changes of the SA node.
                                        iii.    Cardiac pacemaker may be required if the drug therapy used to treat the tachycardiac produces bradycardia.
                                        iv.    Drugs used that may decrease heart rate are:

1.     Digoxin, calcium channel blockers, and Beta blockers.

                                         v.    ANESTHETIC CONSIDERATIONS
1.     These patients may be on an anticoagulant.
2.     May require a temporary pacemaker if Bradycardia occurs.
3.     Evaluation of EKG.
4.     Preop assessment of symptoms:

a.     Syncope, dizziness, or patients may be asymptomatic.
g.    PREMATURE VENTRICULAR BEATS

                                          i.    Usually not treated unless > 6b/min, or multifocal[WU36] .
                                         ii.    Lidocaine- 1-2mg/kg
                                        iii.    Treat the underlying cause:

1.     Hypoxemia
2.     Hypercarbia
3.     Hypokalemia
4.     MI

h.     VENTRICULAR TACHYCARDIA

                                          i.    Is identified as PVC’s > 3 in a row.
                                         ii.    The QRS is wide- > 0.12 sec
                                        iii.    HR > 120
                                        iv.    Asymptomatic VT

1.     Lidocaine- 1-2mg/kg
2.     Procainamide- Slows cardiac conduction impulses (blocks the rapid influx of sodium during phase O depolarization)1.5mg/kg over one minute and repeat every 5 min (15mg/kg max).
                                        
                                        v.    Symptomatic VT

1.     External defibrillation

i.      PROLONGED QT INTERVAL

j.       

                                          i.    QTc > 0.44s
                                         ii.    Associated with ventricular dysrrhythmias and sudden death.
                                        iii.    Treatment

1.     Avoid increasing SNS activity
2.     Beta blockers (esmolol)
                                        iv.    Seen in : Patients with a congenital imbalance of the autonomic innervation to the heart.

                                         v.    The patient may require cardioversion.

k.     WOLF-PARKINSON WHITE SYNDROME


                                          i.    Caused from an abnormal accessory pathway through the bundles of kent [WU37] from the atria to the ventricle.

                                         ii.    The AV node serves as the gait keeper electrical impulses from the SA node. If the SA fires at an increased rate (ie Afib), the AV node will block half those impulses.

                                        iii.    The AV is also responsible for slowing of conduction.

                                        iv.    With WPW atrial impulse will travel through the AV node and directly to the ventricles.
                                         v.    The rate of conduction through the accessory pathway is significantly increased.
                                        vi.    Cardiac arrhythmias in addition to increased ventricular rate may lead to cardiac arrest.

                                       vii.    EKG

1.     Delta waves[WU38] 
2.     A short PR interval
3.     Wide QRS
4.     May see T wave changes

                                      viii.    TREATMENT
1.     May depend on the type of re-entry tachyarrhythmia.
a.     Orthodromic AVRT-


                                                                                          i.     Narrow complex QRS
                                                                                         ii.    The electrical signal travels through the AV node and then retrograde[WU39]  back to the atria, exciting the atria at a rapid rate.

b.    Antidromic AVRT-

                                                                                          i.    Wide complex tachycardia
                                                                                         ii.    Conduction occurs through the accessory[WU40]  pathway and antigrade through the AV node
c.     WPW with Atrial fibrillation

                                        ix.    ORTHODROMIC AVRT

1.     Treat with carotid massage if asymptomatic, or valsalva maneuver.
2.     Adenosine 6-12mg IV
3.     If unsuccessful, verapamil can be given or beta blockers

                                         x.    ANTIDROMIC AVRT

1.     Treatment is intended on blocking the conduction pathway.
a.     Drugs that slow AV node conduction will not affect this type of wpw[WU42] 
2.     Verapamil is not indicated here because of its inability to block cardiac conduction along the accessory pathway, and also increase hypotension.
3.     Digoxin is also not indicated for the same reasons.
4.     May give procainamide if systolic bp is > 90

a.     10mg/kg IV
b.    Rate max 50mg/min
c.     Slows the conduction along the accessory pathway[WU43] .

5.     Cardioversion

                                        xi.    SPECIAL CONSIDERATIONS FOR AFIB AND WPW

1.     Treatment

a.     Procainamide
b.    Verapamil and Digoxin are contraindicated

                                                                                          i.    These drugs block conduction through the AV node and will enhance conduction through the accessory pathway.

c.     Cardiovesion- if hemodynamically unstable.

                                       xii.    ANESTHETIC MANAGEMENT

1.     Aimed at decreasing sns activity.
2.     Give sedative to reduce anxiety.
3.     Glyco and scopalamine preop is ok.
4.     Have drugs to treat tachyarrhythmias available.
5.     Have cardioversion available.
6.     Avoid the use of ketamine.
7.     Give NMB to facilitate intubation.

20.  ARTIFICIAL PACEMAKERS

a.     Considerations:

                                          i.    preop-know the types of pacemaker
                                         ii.    Rate that it’s set.
                                        iii.    s/s. Any dizziness or syncope in the past with the pacemaker.
                                        iv.    A heart rate lower than the preset( by 10%) rate= battery malfunction.
                                         v.    Rate of atrial/ventricular pacing indicates good generator function.
                                        vi.    An irregular heart beat= pulse generator malfunction.

b.    ANESTHETIC MANAGEMENT
                                          i.    Use of anesthetic drugs are not influenced by an artificial pacemaker.
                                         ii.    Have atropine or isoproteronol ready in the event of failure or systole.
                                        iii.    Have grounding pad for cautery placed as far from the generator as possible.
                                        iv.    Have external converter magnet in the room (converts pacer from synchronized to a synchronized mode).
                                         v.    Insertion of a PA catheter does not affect the pacemaker unless it is less than 2wks[WU44]  old.





 [WU1]Halothane, enflurane and iso depress SA node automaticity; only modest direct effects on AV node, prolonged conduction time and incr refractoriness

VAAs decr heart contractility by decr entry of Ca2+ into cells (T&L Ca2+ channels) and decrease sensitivity of contractile proteins to Ca2+

 [WU2]6 Months or less; may postpone elective surgery

 [WU3]Big bowel cases, trauma, thoracic surgery

 [WU4]Invasive = cardiac cath; airline pilots need cardiac cath
Female > 45 y/o and male > 40 y/o needs preop EKG

 [WU5]Standard to assess for arrhythmias; usually atrial (can see P waves well)

 [WU6]Ischemia (ST changes);
Compare abnormal EKGs to previous or may need to get cardiac clearance

 [WU7]Candidate for cardiac cath

 [WU8]Chemical EST

 [WU9]Won’t be able to tell you heart function; EF is not accurate

 [WU10]Check liver function; continue beta-blocker intraop

 [WU11]3-5 beats in a row
If occurs intraop: draw labs, lidocaine, ST changes?

 [WU12]MR that develops intraop usually signifies an MI

 [WU13]V4R; R ventricular MI; do not vasodilate; pt is dependent on preload

 [WU14]Induction, intubation, emergence, surgical stimulation
Can give esmolol preop (b-blocker)
Try to minimize ischemia esp during induction or can become extremely hypotensive – may give phenylephrine, etomidate, narcotic induction (50-150 mcg/kg)
HTN pts have higher swings in BP; give lower doses initially

 [WU15]Increases CO and HR

 [WU16]Placing NGT/OGT is very stimulating; increase VAA, B-blocker, narcotic

 [WU17]Quick onset/ short duration

 [WU18]Give in holding area

 [WU19]Give small dose

 [WU20]Hypotension is usually volume related
**TACHYCARDIA has the largest effect on myocardial O2 demand

 [WU21]Low EF; VAA can cause myocardial depression
Sufentanyl or remifentanyl gtt with nitrous
Do not use pancuronium or succs; can incr HR

 [WU22]May lower dose of anticholinergic esp if cardiac pt is already tachycardic

 [WU23]meperidine

 [WU24]hypotension may occur

 [WU25]related to HTN

 [WU26]can cause profound responses; 10 mcg

 [WU27]if requiring a lot of blood draws

 [WU28]if you put it in you should be using it à shoot CO, PAWP

 [WU29]MAP below a certain level if chronically HTN can cause organ ischemia – particularly in brain

 [WU30]More likely to progress to 3rd degree HB

 [WU31]May require pacing

 [WU32]Transvenous or zoll

 [WU33]First positive deflection is R prime

 [WU34]Two R positive deflections

 [WU35]L BBB that developed intraop requires cardiac evaluation postop.  Do not place PAC into patient with existing L BBB à PAC can cause R BBB which will cause complete HB

 [WU36]Runs of vtach; look at elytes
Lidocaine if elytes normal
Postop EKG and eval

 [WU37]= accessory pathways

 [WU38]Can be seen in young athletes

 [WU39]Going back to atria through accessory pathways

 [WU40]SA à AP à reeneters through AV node

 [WU41]Usually leads to cardiac arrest

 [WU42]Will only enhance entry

 [WU43]But not along AV node pathway

 [WU44]Cautery can interfere with pacemaker
Defibrillator needs to be deactivated
Need external defib during case

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