Cardiac Surgery.pdf

VASCULAR SURGERY

Dr. D.S. Kucey and Dr. C.M. Peniston

Alex Kulik and Ted Rapanos, chapter editors

Neety Panu, associate editor

PREOPERATIVE ASSESSMENT . . . . . . . . . . . . 2

History and Physical Exam

Consent

Preadmission Tests and Orders

Preoperative Medications

CARDIAC TRANSPLANTATION . . . . . . . . . . . . . 17

CONGENITAL HEART SURGERY . . . . . . . . . . . . 18

Palliative Procedures

Pure Obstructive Lesions

Simple Left-to-Right Shunts

Right-to-Left Shunts

Complex Cyanotic Defects

SURGERY

COMMON POSTOPERATIVE . . . . . . . . . . . . . . . 4

COMPLICATIONS

Arrhythmias

Bleeding

Renal Failure

Respiratory Failure

Low Cardiac Output (CO) and

Intra-aortic Balloon Pump (IABP)

Cardiac Tamponade

Perioperative Myocardial Infarction

Hypertension

Postoperative Fever

CNS Complications

. . . . . . . 3

VASCULAR - ARTERIAL DISEASES . . . . . . . . . 22

Acute Arterial Occlusion/Insufficiency

Chronic Aterial Occlusion/Insufficiency

Critical Ischemia

Abdominal Aortic Aneurysm (AAA)

Abdominal Aortic Dissection

Ruptured Abdominal Aortic Aneurysm

Cartoid Surgery

VASCULAR - VENOUS DISEASES . . . . . . . . . . . 27

Anatomy

Deep Venous Thrombosis (DVT) (Acute)

Superficial Thrombophlebitis

Varicose Veins

Chronic Deep Venous Insufficiency (post phlebitic

Syndrome, Ambulatory Venous Hypertension)

Lymphatic Obstruction/Lymphangitis

CARDIAC ANESTHESIA . . . . . . . . . . . . . . . . . . . 7

Preoperative

Intraoperative Anesthesia

Intraoperative Monitoring

Postoperative

PRINCIPLES OF CARDIOPULMONARY . . . . . 8

BYPASS (CPB)

VASCULAR - TRAUMA . . . . . . . . . . . . . . . . . . . . . 31

Penetrating (Laceration)

Blunt (Contusion, Spasm, Compression)

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

MYOCARDIAL PROTECTION AND . . . . . . . . . 10

CARDIOPLEGIA

CORONARY ARTERY BYPASS GRAFT . . . . . .11

SURGERY

VALVE REPLACEMENT AND REPAIR . . . . . .13

Aortic Stenosis (AS)

Aortic Regurgitation (AR)

Choice of Aortic Valve Prosthesis

Mitral Stenosis (MS)

Mitral Regurgitation (MR)

Choice of Mitral Valve Prosthesis

AORTA REPLACEMENT AND REPAIR . . . . . .16

Thoracic Aortic Dissection

Thoracic Aorta Aneurysm

Traumatic Aortic Disruption

MCCQE 2006 Review Notes

Cardiac and Vascular Surgery – CVS1

CARDIAC AND

ASSESSING RISK AND BENEFIT OF

PREOPERATIVE ASSESSMENT

HISTORY AND PHYSICAL EXAM

history of present illness

• inquire about symptoms of cardiac disease i.e. chest pain, dyspnea, fatigue, hemoptysis, syncope,

palpitations, peripheral edema, cyanosis

• determine the degree of physical disability caused by cardiac symptoms

(angina, shortness of breath (SOB), undue fatigue, palpitations) using the

New York Heart Association (NYHA) functional classification (see Table 2 Cardiology Chapter)

• determine severity of angina pectoris using the Canadian Cardiovascular

Society classification (see Table 1 Cardiology Chapter)

past medical history

• cardiac risk factors: smoking, family history, elevated cholesterol,

diabetes mellitus (DM), hypertension (HTN), +/– elevated homocysteine levels

• previous operations: thoracotomy, saphenous vein stripping/ligation, peripheral vascular surgery,

carotid endarterectomy

• allergies, medications i.e. anticoagulants, antiarrhythmics,

antiplatelet agents, ACE inhibitors, diuretics, etc.

family and social history

• family history of coronary artery disease (CAD), congenital heart disease, Marfan syndrome,

malignant hyperthermia and other hereditary disorders should be noted

• consider marital status and living conditions in discharge planning

review of symptoms

• cardiovascular: past cardiac procedures, and investigations

• CNS: previous transient ischemic attack (TIA) or stroke (requires full neurologic work-up)

• respiratory: if chronic obstructive pulmonary disease (COPD) is suspected, obtain spirometry,

pulse oximetry and ABG pre-op

• endocrine: DM and its complications should be noted

• hematologic: bleeding disorders, sickle cell screening if African heritage

• renal: impaired renal function and renal dialysis increase the risk of perioperative complications;

renal transplant patients should be followed by renal transplant service

perioperatively to manage medications

• gastrointestinal (GI): active peptic ulcer disease, active hepatitis, cirrhosis,

and other GI problems can seriously affect the outcome of cardiac surgery

• peripheral vascular: venous and arterial disease should be noted; intra-aortic balloon pump insertion

through a femoral artery may be difficult with aorta-iliac occlusive disease

• genitourinary (GU): prostate problems may impair Foley catheter insertion

• musculoskeletal (MSK): major skeletal deformities or active arthritic conditions may interfere

with airway management, ambulating, and recovery

physical examination

• height, weight, and vital signs

• examine mouth, airway, neck, chest and abdomen

• assess all peripheral pulses and auscultate the carotid and subclavian arteries for bruits

• examine saphenous veins

• perform Allen's test on both hands in case a radial artery is used as a bypass conduit

for coronary artery bypass

• infection following cardiac surgery can be disastrous, therefore rule

out skin infections and dental caries (especially prior to valve surgery)

CONSENT

risks and benefits of surgery should be clearly outlined to the patient and his/her family

(with patient's permission)

serious complications should be explained, such as death, stroke, myocardial infarction (MI), infection, etc.

PREADMISSION TESTS AND ORDERS

CBC, PTT, INR, electrolytes, glucose, BUN, creatinine, and other special blood tests as needed

urinalysis

PA and lateral CXR (+/– CT chest, especially in re-operations to determine relation

of sternum to heart and ascending aorta)

ECG to diagnose heart rhythm abnormalities and myocardial ischemia

cross and type for 2 units PRBCs

NPO after midnight

Dulcolax suppository preop

ancef 1 g IV to be given in OR (vancomycin 1 g IV or clindamycin 600 mg IV if penicillin allergic)

CVS2 – Cardiac and Vascular Surgery

MCCQE 2006 Review Notes

PREOPERATIVE ASSESSMENT . . . CONT.

PREOPERATIVE MEDICATIONS

All regular cardiac medications should be continued to the morning of surgery (including nitro patch), except:

• amiodarone - should be stopped 4 weeks preop to avoid potential intraoperative problems

(resistant bradycardia, hypotension, etc.)

• ACE inhibitors - small risk of hypotension perioperatively with these drugs,

therefore stop 24 hours preop (controversial)

anticoagulants

• warfarin - stop 4-5 days prior to surgery; admit and start on IV heparin if high risk of thrombosis

large left atrium, atrial fibrillation (A fib), mitral valve prosthesis

• heparin - IV heparin should be stopped 2-3 hours preop

(unless on intra-aortic balloon pump (IABP) support)

• ASA/Ticlodipine/NSAIDs - stop 7-10 days preop if possible

psychotropic drugs

• MAO inhibitors - discontinue 3 weeks preop if long acting, 1 week if short acting

others

• steroids and anti-rejection drugs (transplant patients) must be continued

ASSESSING RISK AND BENEFIT OF SURGERY

ventricular function

• the most important determinant of outcome of all heart diseases

• patients with severe left ventricular (LV) dysfunction usually have a poor prognosis,

but surgery can sometimes dramatically improve LV function

• patients with severe LV dysfunction but good arteries to bypass usually do very well from the

operative risk viewpoint, but those with bad ventricles and marginally graftable coronary arteries

are usually poor surgical candidates

• to assess viability of non-functioning myocardial segments, use thallium and

sestamibi myocardial imaging, PET scanning or MRI (see Cardiology chapter)

• surgically correcting volume overloading conditions such as aortic or mitral regurgitation (AR/MR)

may not change the prognosis (due to irreversibly damaged myocardium)

but symptomatology can be improved

• depressed ventricular function caused by aortic stenosis almost always improves

following relief of obstruction

coronary artery disease (CAD)

• isolated proximal disease in large coronary arteries (>1.0 - 1.5 mm) is ideal for bypass surgery

• small, diffusely diseased coronary arteries are not suitable for bypass surgery

• see Cardiology Chapter for discussion of PTCA vs. surgery

heart valve disease

• repair of heart valves is preferable to replacement because the ideal artificial valve

has not yet been developed

• repair is not feasible in all patients with heart valve disease, therefore valve replacement is necessary

numerous risk factors for CABG mortality have been identified in several major studies

(in decreasing order of significance)

• urgency of surgery (emergent or urgent)

• reoperation

• older age

• poor ventricular function

• female gender

• left main disease

• others include catastrophic conditions (cardiogenic shock, ventricular septal rupture, ongoing CPR),

dialysis-dependent renal failure, end-stage COPD, diabetes, cerebrovascular disease,

and peripheral vascular disease

commonly identified factors found to increase CABG post-operative morbidity or length of stay

(in decreasing order of significance):

• reoperation

• emergent procedure

• preoperative usage of intra-aortic balloon pump (IABP)

• congestive heart failure (CHF)

• CABG-valve surgery

• older age

• renal dysfunction

• COPD

• DM

• Cerebrovascular disease (CVD)

see Table 1 - Cleveland Clinic Clinical Severity Scoring System

MCCQE 2006 Review Notes

Cardiac and Vascular Surgery – CVS3

ASSESSING RISK AND BENEFIT OF SURGERY . . . CONT.

Table 1. Cleveland Clinic Clinical Severity Scoring System

Preoperative Factor

Score

Added Score

Morbidity*

Mortality

Emergency Case

0-2

4-7%

0-2%

Creatinine 141-167 umol/L

3-5

10%

2-4%

Creatinine >168 umol/L

18%

Severe LV dysfunction

7-9

23%

Reoperation

10+

> 50%

> 25%

Mitral Regurgitation

Age 65-74

Age 75+

Prior vascular surgery

Hematocrit <34%

Aortic stenosis

Diabetes

Cerebrovascular disease

*Morbidity defined as myocardial infarction requiring use of IABP, mechanical ventilation for 3+ days, neurological deficit, oliguric or anuric renal

failure, or serious infection.

Adapted from Higgins et al. Stratification of morbidity and mortality outcome by preoperative risk factors in coronary artery bypass patients. JAMA. 1992:267:234-8.

COMMON POSTOPERATIVE COMPLICATIONS

ARRHYTHMIAS

ventricular ectopy most common

• premature ventricular contractions (PVC's) are usually benign, but may reflect marginal coronary

perfusion and ongoing myocardial ischemia

• if frequent (> 6-10/min) or multifocal PVCs, check serum electrolytes,

repeat 12 lead ECG and assess hemodynamics

• treatment

• Lidocaine 100 mg IV bolus (may repeat 50 mg IV bolus), followed by drip at 1-4 mg/min

• Magnesium sulfate 2-4 g IV, may repeat

• Amiodarone 150 mg IV slowly over 15-30 minutes,

then 900-1,200 mg (in 250 cc D5W) over 24-48 h

• cardioversion needed if progresses to symptomatic ventricular tachycardia (VT)

or if patient develops ventricular fibrillation (V fib)

• atrial or atrioventricular pacing at a slightly higher rate may suppress ectopy

nodal or junctional rhythm

• treatment may not be necessary (assure no hypotension)

• rule out digoxin toxicity, make certain serum K + > 4.5, rule out hypomagnesemia

• may require A-V sequential pacing if loss of atrial kick has significant hemodynamic sequelae

supraventricular tachycardia (SVT) - includes atrial fibrillation (A fib) and flutter

• onset may be heralded by multiple premature atrial contractions (PAC's)

• atrial ECG using atrial pacing leads often helpful in distinguishing fibrillation from

flutter during rapid rates

• treatment of A fib

• digoxin used to control rate - 0.5 mg IV once, then 0.25 mg q6h x 2,

then 0.125-0.375 mg PO daily depending on body weight and renal function

• if no asthma/COPD: metoprolol 5 mg IV q15min x 3, then 25-50 mg PO bid

• if asthma/COPD: diltiazem 0.25 mg/kg IV bolus (further 0.35 mg/kg bolus if

inadequate response), then switch to amiodarone 400 mg PO tid x 3-5 days,

then 200 mg PO od after loading dose

• if unstable or Grade IV LV: consider amiodarone 150 mg IV bolus (can repeat),

then 900 mg IV over 24 h, then switch to PO amiodarone as above

• treatment of atrial flutter

• rapid atrial pacing > 400 bpm

• digitalization followed by IV beta blocker

• IV verapamil followed by digitalization (calcium channel blockers must be used judiciously

as wide complex SVT can mimic VT)

• in both instances, the arrhythmia should be treated with synchronous direct current (DC) cardioversion

at 25-50 joules should there be a significant drop in blood pressure (BP) or cardiac output (CO)

• never give IV CCB and B blocker together

• adenosine can be used as a diagnostic and therapeutic intervention

(transient bradycardia/asystole to allow interpretation of rhythm, may be therapeutic)

CVS4 – Cardiac and Vascular Surgery

MCCQE 2006 Review Notes

COPD

Weight <65 kg

COMMON POSTOPERATIVE COMPLICATIONS . . . CONT.

outcome

• mortality rates 0.3-23% depending on the degree of azotemia

• if dialysis is required, mortality ranges from 27-53%

RESPIRATORY FAILURE

mechanical - mucous plugging, malpositioned endotracheal tube, pneumothorax,

pre-existing COPD, bronchospasm

intrinsic - volume overload, pulmonary edema, atelectasis, pnemonia, pulmonary embolus

(uncommon), acute respiratory distress symptom (ARDS)

management

• examine patient and evaluate CXR for correctable causes

• if intubated: add positive end-expiratory pressure (PEEP) (7.5-10 cm H 2 O),

increase % oxygen inspired (FiO 2 ), diuresis, consider bronchoscopy with lavage for sputum,

bronchodilators

• if extubated: pain control, chest physio, diuresis, increase FiO 2 ,

facial continuous positive air pressure (CPAP), bronchodilators

• if pneumonia: sputum culture and gram stain, bronchoscopy,

consider antibiotics early if prosthetic materials in heart

LOW CARDIAC OUTPUT (CO)

cardiac index < 2.0 L/min/m 2

signs - decreased urine output, acidosis, hypothermia, altered sensorium, cool clammy skin

assessment - heart rate and rhythm (ECG: possible acute MI), preload and afterload states

(Swan-Ganz catheter readings), measurement of CO

treatment

• stabilize rate and rhythm

• optimize volume status, systemic vascular resistance (SVR)

• consider ECHO to rule out tamponade

• give calcium chloride 1 g IV until more definitive diagnosis reached

• correct acidosis, hypoxemia if present (CXR for pneumothorax)

• inotropic agents if necessary - see Table 4

• Dopamine: increases SVR, protects renal function (increases renal blood flow,

GFR and sodium excretion), produces tachycardia only in high doses

• Dobutamine: increases CO, decreases LV pressure, decreases SVR

• Epinephrine: increases heart rate, contractility and stroke volume (SV), decreases urine flow

• Norepinephrine: increases mean arterial pressure (MAP) with less increase in HR

compared to epinephrine

• Milrinone: improves cardiac output and myocardial contractility, decreases systemic

and pulmonary vascular resistance without increasing HR, used for right ventricle (RV)

failure or high pulmonary artery (PA) pressure

• Amrinone: similar to milrinone but more prone to cause arrhythmias in high doses

• persistent low cardiac output despite inotropic support requires placement of IABP

MCCQE 2006 Review Notes

Cardiac and Vascular Surgery – CVS5

BLEEDING

causes include medications, clotting deficits, prolonged operation, emergency surgery,

technical factors, deep hypothermia, renal impairment, and transfusion reactions

patients at high risk for bleeding complications: endocarditis, aortic dissection, redo cases

treatment

• assure normothermia

• measure clotting factors stat: INR, PTT, fibrinogen, platelet count, activated clotting time

• tranexamic acid bolus (50 mg/kg) occasionally given if > 150 cc/h chest tube output

• correct with fresh frozen plasma, cryoprecipitate, platelets, DDAVP,

protamine for continued heparinization

• transfusion reaction protocol if suspected

indications for surgical exploration of post-operative hemorrhage

• mediastinal tube output > 300 cc/h despite correction of clotting factors

• 1.5% rate for CABG, 4% rate for valve surgery

• technical factors found as cause > 50% of time

RENAL FAILURE

incidence is 0.3-1%

diagnosis - prerenal vs. renal vs. postrenal

management

• optimize volume status and cardiac output

• discontinue nephrotoxic drugs (indomethacin, aminoglycosides, ACE inhibitors)

• maintain urine output > 40 cc/h using low-dose dopamine (1-3 ug/kg/h),

furosemide 10-300 mg IV bolus +/– 10-20 mg/h drip, or ethacrynic acid (50-100 mg IV bolus) as indicated

• furosemide/mannitol drips if persistent oliguria

• dialysis

• continuous arterial-venous hemodialysis (CAVHD) or continuous venous-venous (CVVHD)

approach are most suitable for hemodynamically unstable patients

• for hemodynamically stable patients, consider intermittent hemodialysis or peritoneal dialysis

(peritoneal cavity may communicate with mediastinum and be ineffective)

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