Should thyroid function be assessed before cardiopulmonary bypass operations?

Combined Open-Heart Coronary Artery Bypass Surgery and Subtotal Thyroidectomy in a 54-year-old patient: A Case Report

Background

Combined open-heart surgery and thyroidectomy is a rare procedure. However, some difficulties will occur for cardiac surgery when thyromegaly extends into the retrosternal space.

Case Details

A 54-year-old woman suffering from dyspnea, chest pain and decreased left ventricular function (EF=40%) was diagnosed with coronary artery disease (3 vessel disease) and became candidate for coronary artery bypass grafting (CABG). Also, she had multinodular goiter with normal thyroid function test. After midsternotomy, a huge goiter was seen in the upper mediastinum. Because the mass had covered the ascending aorta and involved the posterior aspect of the innominate vein making access to aorta impossible, thyroidectomy was performed at first followed by CABG. Post-operation course was satisfactory. Fourteen months later, the patient was euthyroid and in NYHA class 1.

Conclusion

The evidence of the case showed that combined CABG and thyroidectomy can be performed safely.

Does a combined procedure for cardiac surgery and thyroidectomy offer acceptable outcomes?

This best evidence topic on cardiothoracic surgery was written using a structured protocol. The question addressed was: 'in an adult patient requiring cardiac surgery, can a thyroidectomy for a large retrosternal goitre be performed with good outcomes as a combined procedure?' Of 150 papers identified through the literature search, 16 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, study type, patient group studied, relevant outcomes and results were tabulated. This paper includes 3 Level 4 papers and 13 case reports. All papers reported postoperative outcomes and five papers reported intraoperative outcomes. Of a total cohort of 32 patients, 25 were euthyroid prior to combined surgery. Twenty-nine of 32 thyroid surgeries were performed immediately prior to cardiac surgery in the combined procedure sequence. Post-procedural complications including transient recurrent laryngeal palsy and tracheomalacia were reported in 8 patients. There was one intraoperative death. Where reported, all patients were euthyroid on follow-up. All identified papers reported good outcomes with combined thyroidectomy and cardiac surgery.

Combined thyroidectomy and cardiac surgery

A combination of cardiac surgery and thyroidectomy as a single stage operation has rarely been reported in the literature. We report on the management of a 64-year-old female undergoing a combined aortic valve replacement and excision of a primary (ectopic) intrathoracic goiter. The literature on combined cardiac surgery and thyroidectomy is also reviewed.

Epidemiology, Mechanisms, and Risks

Atrial fibrillation (AF) is one of the most frequent complications of cardiac surgery, affecting more than one third of patients. The mechanism of this arrhythmia is believed to be reentry. The electrophysiologic substrate may be preexisting or may develop due to heterogeneity of refractoriness after surgery. Multiple perioperative factors have been proposed to contribute to the latter, including operative trauma, inflammation, elevations in atrial pressure (including that due to left ventricular diastolic dysfunction), autonomic nervous system imbalance, metabolic and electrolyte imbalances, or myocardial ischemic damage incurred during the operation. Whether ectopic beats originating in the pulmonary veins explain at least some episodes of postoperative AF, as has been shown for nonsurgical patients with the arrhythmia, is of current interest as such sites could easily be isolated at the time of surgery. The development of postoperative AF is associated with a higher risk of operative morbidity, prolonged hospitalization, and increased hospital cost compared with that in patients remaining in sinus rhythm. Many factors have been identified as being associated with postoperative AF, but the most consistent variable across studies is increasing patient age. It is speculated that age-related pathologic changes in the atrium contribute to arrhythmia susceptibility. An important modifiable risk factor for postoperative AF is the failure to resume therapy with beta-adrenergic receptor blockers after surgery. The stratification of patients who are at higher risk for AF would focus preventative strategies on patients who are most likely to benefit from such therapy. Nonetheless, since postoperative AF often develops in patients with comorbidities who are predisposed to other complications and prolonged hospitalization, it is presently unclear whether the prevention of postoperative AF will result in improved patient outcomes, particularly shorter hospitalizations.

Atrial fibrillation and cardiac surgery

PURPOSE OF REVIEW

To discuss the pathophysiology, risk factors, and treatments for atrial fibrillation occurring after cardiac surgery.

RECENT FINDINGS

Atrial fibrillation occurs frequently after cardiac surgery and it may lead to patient morbidity. Many variables have been suggested to be associated with this arrhythmia, but only advanced patient age can consistently identify risk for this complication. Immediate electrical cardioversion is indicated when the arrhythmia leads to hemodynamic instability or myocardial ischemia. Otherwise treatment is aimed at heart rate control, elective cardioversion with drugs or electrical means, and anticoagulation when the arrhythmia persists. Multiple investigations have evaluated methods for preventing postoperative atrial fibrillation, but only beta-adrenergic receptor blocking drugs have been consistently shown to be effective, and then not in all patients. Surgical treatments are increasingly being considered as a therapeutic means for ameliorating chronic atrial fibrillation. The use of these procedures has been simplified with the development of devices that can generate linear scars in the atrium and around the pulmonary vein orifices. These simplifications will allow for broader application of these techniques to patients undergoing other cardiac surgery (e.g. mitral valvular surgery).

SUMMARY

Atrial fibrillation is one of the most common complications of cardiac surgery. There are three major aims for treating atrial fibrillation: conversion to sinus rhythm, heart rate control, and anticoagulation. Only beta-blockers can be recommended for prophylaxis against postoperative atrial fibrillation. Further refinements in surgical treatments for atrial fibrillation may allow for wider applications of this therapy with lower rates of complications.

Effects of intravenous triiodothyronine during coronary artery bypass surgery

A prospective randomized and double-blind study was performed to evaluate whether perioperative triiodothyronine administration has any effect on cardiovascular performance after coronary artery bypass surgery. Sixty patients were assigned to 2 groups of 30 each. When crossclamping ended, group A received an intravenous bolus of triiodothyronine, followed by infusion for 6 hours. Group B received a placebo. Serum triiodothyronine levels and hemo-dynamic parameters were serially measured. Mean postoperative cardiac index was slightly, but not significantly, higher in group A, whereas systemic vascular resistance was significantly lower in group A. Compared with preoperative values, serum triiodothyronine levels dropped significantly in group B at the end of cardiopulmonary bypass and remained low 12 hours postoperatively, while levels rose significantly in group A. No significant differences were detected between the groups in the incidence of arrhythmia, the need for inotropic support, intensive care unit stay, mortality, and morbidity. Perioperative administration of triiodothyronine increased cardiac output slightly and decreased systemic vascular resistance, but it had no effect on operative outcome. Routine use after coronary surgery is thus not recommended.

Thyroid function in infants following cardiac surgery: comparative effects of iodinated and noniodinated topical antiseptics

OBJECTIVES

Cardiopulmonary bypass has profound effects on thyroid hormone metabolism. These effects may be exacerbated in infants because they are able to absorb large quantities of iodine transcutaneously. The purpose of this study was to test the hypothesis that preoperative povidone-iodine contributes to postoperative thyroid depression in infants who undergo cardiac surgery.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Children's Hospital and Medical Center, Seattle, WA.

PATIENTS

Thirty-seven infants undergoing repair of congenital cardiac defects.

INTERVENTIONS

Infants requiring cardiopulmonary bypass were divided into two groups: Group 1 received povidone-iodine; group 2 received chlorhexidine as a topical preoperative antiseptic. Group 3 did not require cardiopulmonary bypass for repair of cardiac defects and received povidone-iodine as a preoperative antiseptic.

MEASUREMENTS AND MAIN RESULTS

Thyrotropin (TSH), total triiodothyronine (T3), and thyroxine (T4) were measured at four intervals: a) before preparation for surgery; b) immediately after surgery; c) at 2 days after surgery; and d) at 5 to 8 days after surgery. There was a significant decrease in TSH concentrations immediately after surgery in the two bypass groups. This change was significantly greater than in the change in TSH concentration in the thoracotomy group. Total T3 and T4 concentrations decreased by postoperative day 2 in both groups 1 and 2, and the changes were significant compared with group 3. Total T3 and T4 concentrations increased significantly in all groups after postoperative day 2, with no significant difference between the three groups.

CONCLUSION

Cardiopulmonary bypass has a more significant effect on thyroid hormone metabolism than does the preoperative antiseptic.