DESCRIPTION

• Review of the evaluation and management of patients prior to cardiac surgery including coronary artery bypass graft (CABG) surgery, valve repair or replacement, repair of congenital heart disease, as well as novel techniques (eg, robotic-assisted, minimally invasive).
• Advances in medical and percutaneous therapies for coronary artery disease (CAD) have resulted in older and sicker patients referred for cardiac surgery, emphasizing the need for preoperative risk assessment.

EPIDEMIOLOGY

According to AHA, 694,000 open-heart procedures, including 104,000 valve replacements and 448,000 CABG operations, were performed in the U.S. in 2006. 2,210 cardiac transplantations were performed in the U.S. in 2007.

RISK FACTORS

• The major risk factors for adverse outcomes during CABG include advanced age, emergency surgery, history of prior CABG, a creatinine concentration of 2 mg/dL, and dialysis dependency.
• The 2007 Society of Thoracic Surgeons (STS) risk models predict the risk of operative morbidity and mortality after adult cardiac surgery using demographic and clinical variables. The online STS risk calculator is easily accessible and is used by physicians and patients to understand the possible risks of surgery. The STS currently has 3 risk models (CABG, valve, and CABG + valve) and can be found online at http://209.220.160.181/STSWebRiskCalc261/. The models apply to 7 specific surgical procedure classifications (shown below):
• CABG model:
  • 1. Isolated CABG
• Valve model:
  • 2. Isolated aortic valve replacement
  • 3. Isolated mitral valve replacement
  • 4. Isolated mitral valve repair
• Valve + CABG model:
  • 5. Aortic valve replacement + CABG
  • 6. Mitral valve replacement + CABG
  • 7. Mitral valve repair + CABG
• Each risk model was developed for the following 9 endpoints: Operative mortality, permanent stroke, renal failure, prolonged ventilation >24 hr, deep sternal wound infection, reoperation for any reason, major morbidity or operative mortality, short stay <6 days, and long stay >14 days.
• The STS model only calculates a predicted risk value for adult patients age 18–110 yr for which both age and gender are known. The models for renal failure do not calculate a predicted risk value for patients who are on dialysis preoperatively. (STS Adult Cardiac Surgery Database Risk Model Variables—Data Version 2.61).

ETIOLOGY

Pending underlying illness

COMMONLY ASSOCIATED CONDITIONS

Potentially increase morbidity and mortality (see list in preceding section)

Outline

• Description
• Epidemiology
• Risk Factors
• Etiology
• Commonly Associated Conditions

History

Pertinent findings:

• Active infections (urinary tract, pneumonia)
• Anemia/bleeding disorders
• Current medications
• DM
• Drug allergies
• Liver dysfunction (alcohol, cirrhosis)
• Neurologic symptoms (previous TIA, stroke, carotid endarterectomy)
• Peripheral vascular disease
• Poor family support
• Poor nutritional status
• Renal insufficiency
• Peptic ulcer disease/GI bleeding
• Pulmonary disease (smoking, COPD)

Physical Exam

Pertinent findings:

• Aortic regurgitation, which can worsen during cardiopulmonary bypass
• Prior radical mastectomy, which contraindicates use of internal mammary artery (compromised thoracic blood supply)
• Carotid bruits increase risk of perioperative stroke. Stenoses >75% require staged or combined procedure.
• Identify baseline neurologic deficits that may worsen postoperatively and provide a reference for assessment
• Infection and dental caries increase risk of endocarditis in valvular heart surgery.
• Intra-aortic balloon pump is contraindicated in aortic regurgitation, severe peripheral vascular disease, abdominal aortic aneurysm, and/or significant aortic atherosclerosis.
• Lower extremity venous varicosities may necessitate use of arm veins or arterial conduits for coronary bypass. Avoid IV lines in veins to be harvested.
• Skin for evidence of infection. Tinea pedis increases risk of lower extremity cellulitis.

DIAGNOSTIC TESTS & INTERPRETATION

• Pulmonary function testing and baseline arterial blood gas if clinically indicated
• Carotid Doppler for carotid bruits or diffuse atherosclerosis
• Intraoperative transesophageal echo used to safely cannulate aorta with aortic atherosclerotic disease

Lab

• Hematology: CBC, PT (INR), PTT, platelet count
• Chemistry: Electrolytes, BUN, creatinine, liver function tests, fasting plasma glucose
• Thyroid function tests and PF4/heparin antibody screen if clinically indicated
• Stool for occult blood
• Urinalysis
• CXR (PA and lateral)
• EKG

Imaging

Pertinent data from cardiac catheterization and echo include:

• Elevated LV end-diastolic pressure and pulmonary capillary wedge pressure:
  • May remain elevated postoperatively
  • Requires adequate preload postoperatively
• Elevated right atrial pressure:
  • May reflect tricuspid valve disease or right ventricular dysfunction
  • May require aggressive volume expansion postoperatively
• Elevated pulmonary artery pressure:
  • Suspect fixed pulmonary vascular resistance when pulmonary artery diastolic pressure > pulmonary capillary wedge pressure
  • May require vigorous oxygenation and pulmonary vasodilator therapy
• LV systolic dysfunction:
  • Decreased ejection fraction increases perioperative risk
  • Perioperative afterload reduction
• RV systolic dysfunction:
  • Increases perioperative risk
  • Perioperative supplemental oxygen to decrease pulmonary vascular resistance
• Aortic stenosis:
  • Moderate aortic stenosis may be treated by prophylactic valve replacement in selected CABG patients
• Aortic regurgitation:
  • LV dimension assists in decision for valve replacement
• Mitral regurgitation:
  • Moderate to severe MR may require concurrent repair or replacement with CABG
• LV aneurysm:
  • Consider indication for aneurysmectomy
• Mural thrombus:
  • Increased risk of perioperative stroke
• Patency of internal mammary arteries
• Patency of saphenous vein grafts

DIFFERENTIAL DIAGNOSIS

None; diagnosis established prior to surgery

Outline

• History
• Physical Exam
• Diagnostic Tests & Interpretation
  • Lab
  • Imaging
• Differential Diagnosis

• ACC/AHA guidelines on CABG surgery recommend these preventive measures to minimize the risk of CABG morbidity and mortality:
  • Aspirin to improve morbidity and mortality
  • -Blockers to prevent perioperative atrial fibrillation (AF); amiodarone and sotalol are alternatives
  • Statin therapy
• Prophylactic antimicrobials to prevent surgical site infection
• Strict glycemic control in diabetic patients (using an insulin infusion) during the perioperative period, which may also reduce sternal wound infection

ADDITIONAL TREATMENT

General Measures

• Arrhythmia prophylaxis:
  • Correct electrolyte abnormalities (potassium 4.0–5.0 mEq/L and magnesium2.0 mEq/L).
• AF prophylaxis:
  • Incidence of AF is 30% in isolated CABG and higher in valve-related surgeries.
  • ACC/AHA/ESC guidelines recommend -blocker prophylaxis as described above unless contraindicated.
  • Prophylactic use of -blockers decreases incidence of post-CABG AF by 70–80%.
  • -Blockers should be resumed promptly after surgery in patients receiving -blockers long-term.
  • Amiodarone or sotalol are alternatives for patients at increased risk of postoperative AF.
  • Amiodarone (PO or IV) prophylaxis given pre- or postoperatively reduces AF, ventricular arrhythmias, stroke, and length of stay.
  • Sotalol reduces the incidence of postoperative AF.
  • Prophylactic calcium channel blockers (CCB) and digoxin do not reduce incidence of AF.
  • Biatrial pacing may be effective in reducing AF postoperatively.
  • If in normal sinus rhythm before surgery and on antiarrhythmic therapy for paroxysmal AF, continue antiarrhythmics until surgery
• Persistent AF:
  • Electrolyte repletion
  • Rate control with -blocker (1st line), CCB, or amiodarone (particularly if hypotensive)
  • Antiarrhythmics (class IA, IC, III) are an alternative for some patients.
  • Perform cardioversion if hemodynamically unstable.
• Ventricular tachyarrhythmias:
  • Ectopy including nonsustained ventricular tachycardia (NSVT) typically occurs between postoperative days 3–5 and up to 50% of patients require therapy.
  • Atrial pacing often reduces ventricular ectopy.
  • For NSVT, magnesium and amiodarone are commonly used.
  • If previously on antiarrhythmic therapy, continue antiarrhythmics until surgery.
  • If on chronic amiodarone with underlying lung disease, consider discontinuing 3 mo preoperatively if no life-threatening arrhythmias.
  • For sustained ventricular tachycardia, overdrive pacing, cardioversion, or IV amiodarone is recommended.
• Bradyarrhythmias:
  • Preoperative temporary transvenous pacemaker recommended in patients with hemodynamic instability or high-grade atrioventricular block (type II 2nd- or 3rd-degree).
  • Permanent epicardial pacing lead implantation for patients undergoing tricuspid valve replacement with a mechanical prosthesis
• Permanent pacemaker:
  • Document make, model, settings of device, and pacemaker dependency
  • Activate magnet mode intraoperatively and reinterrogate postoperatively.
• Implanted automatic cardioverter-defibrillator:
  • Disable prior to surgery to minimize unnecessary shocks by electrocautery and reinterrogate postoperatively.
  • Have back up external cardioverter-defibrillator available.

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

Not indicated preoperatively unless unstable

PATIENT EDUCATION

• Explain to patient that CABG uses his or her own veins or arteries to bypass narrowed areas and restore blood flow to heart muscle.
• CABG can effectively relieve chest pain for most patients, reduces risk of heart attack, improves ability for physical activity, and can prolong life with certain patterns of severe CAD.
• Most people recover in the hospital 4–5 days after surgery. People without complications typically return to desk work within 4–6 wk. Complete recovery from surgery often takes 2–3 mo.
• The final decision regarding the best choice of treatment depends on multiple factors including the benefit versus risk of surgery, the severity of symptoms and cardiac disease, and underlying medical problems. Patients should consult with their healthcare provider.
• For prevention of progression of CAD, patients are recommended to stop smoking, follow a heart-healthy diet, reduce blood cholesterol and high BP, exercise daily, maintain a healthy weight, manage diabetes, reduce stress, and limit alcohol intake.

PROGNOSIS

Operative mortality rates (based on several large studies):

• Isolated conventional CABG 2.5–3.4%
• Isolated off pump CABG 2.5–3.4%
• Minimally invasive direct CABG <2%
• CABG + multiple valve 10.1–18.8%
• MVR 2.4–12%
• AVR 2.1–6.2%
• MVR + CABG 12.8–15.3%
• AVR + CABG 8–8.2%
• Multiple valves 8.7–9.6%
• MV repair 3–6.4%
• AV repair 5.9%
• Minimally invasive MV repair <1.6%
• Minimally invasive MV replacement <5.8%
• Minimally invasive AV replacement 1.6–2%

Outline

• Follow-Up Recommendations
  • Patient Monitoring
• Patient Education
• Prognosis

CODES

ICD9

V72.81 Pre-operative cardiovascular examination

SNOMED

43038000 cardiovascular examination and evaluation (procedure)

CLINICAL PEARLS

• Cardiac surgery is a commonly performed type of surgery worldwide; the use of novel techniques has increased surgical options for patients with cardiovascular disease.
• Increasing numbers of older, sicker patients with multiple comorbidities are referred for cardiac surgery.
• Preoperative risk assessment is essential to performing safe cardiac surgical procedures while minimizing complications.
• The online STS risk models predict the risk of operative morbidity and mortality after adult cardiac surgery using demographic and clinical variables.

Outline

• Codes
  • ICD9
  • SNOMED
• Clinical Pearls

ADDITIONAL READING

• Albert MA, Halevy N, Antman EM. Preoperative Evaluation for Cardiac Surgery. In: Cohn LH, ed. Cardiac surgery in the adult, 3rd ed. New York: McGraw-Hill; 2008:261–280.
• Bojar RM. Manual of perioperative care in adult cardiac surgery, 4th ed. Malden, MA: Wiley-Blackwell; 2005.
• Eagle KA, Guyton RA, Davidoff R, et al. ACC/AHA 2004 guideline update for coronary artery bypass graft surgery: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1999 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation. 2004;110:e340.
• Gray RJ, Sethna DH. Medical Management of the Patient Undergoing Cardiac Surgery. In: Libby P, Bonow RO, Mann DL, et al, eds. Braunwald’s heart disease: A textbook of cardiovascular medicine, 8th ed. Philadelphia: Saunders Elsevier; 2008:1993–2012.
• Reich DL, Mittnacht A, Kaplan JA. Anesthesia and the Patient with Cardiovascular Disease. In: Fuster V, O’Rourke RA, Walsh RA, Poole-Wilson P, eds. Hurst’s the heart, 12th ed. New York: McGraw-Hill: 2008:2021–2032.

J. Ryan Jordan

Nanette K. Wenger