Eur J Cardiothorac Surg 2004;26:773-775
© 2004 Elsevier Science NL
Vocal cord palsy as a complication of adult cardiac surgery: surgical correlations and analysis
Ioannis Dimarakis,
Aristotle D. Protopapas*
Imperial College of Science, Technology and Medicine, London, UK
Received 25 March 2004;
received in revised form 2 June 2004;
accepted 7 June 2004.
* Corresponding author. Address: 26 Windsor Road, Winchester Hants SO22 6NB, UK. Tel./fax: +44-795-689-7683
e-mail: aristotelis.protopapas{at}ic.ac.uk
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Abstract
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Vocal cord palsy after adult cardiac surgery is often attributed to non-surgical mechanisms as tracheal intubation and central venous catheterisation. It may also be caused by injury of the recurrent laryngeal nerves by surgical dissection. We hereby present a review of relevant clinical reports. The cumulative incidence was 1.1% (33 in 2980). Main reported surgical mechanisms of injury were harvesting of internal thoracic artery and topical cold cardioprotection. Bilateral nerve palsy has been lethal on at least one occasion. Where vocal cord injury followed harvesting of the left internal thoracic artery, it was reported ipsilateral to the conduit.
Key Words: Cardiac surgery • Complication • Internal thoracic artery risk management • Vocal cord
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1. Introduction
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Vocal cord paralysis is encountered as a postoperative complication in adult cardiac surgery. Perceived wisdom attributes it to non-surgical mechanisms as tracheal intubation, central venous catheterisation and other. It is, thus, dealt with simple reassurance: no further evaluation is routinely undertaken, the condition deemed self-limited. The patients are not routinely warned of the complication.
1.1. Anatomico-surgical considerations
The vocal cord is in adduction when its abductor muscle (posterior cricoarytenoid) is paralysed by injury of the motor component of the ipsilateral recurrent laryngeal nerve (RLN), branch of the ipsilateral vagus. The non-symmetrical anatomy of the RLN is of surgical significance: the right RLN arises from the vagus, as the latter crosses the first part of the subclavian artery (SA). After hooking backward and upward behind the artery it ascends in the tracheoesophageal groove. The left RLN arises from the vagus as the latter crosses the arch of the aorta in the thorax.
Various mechanisms have been implicated in the development of vocal cord palsy (VCP) after adult cardiac surgery.
1.1.1. Indirect injury from traction
Median sternotomy with sternal retraction results in the application of longitudinal strain to both RLNs via forces generated from the lateral traction of both subclavian arteries. This may be enhanced further by unilateral or even bilateral retraction of the rib cage for harvesting of either internal thoracic artery (ITA) (see below).
1.1.2. Direct trauma
Thermal trauma from topical cardioprotective ice slush and electrocautery or other dissection for harvesting (ITA). Surgical dissection in the subaortic and ITA origin may also lead to neurotmesis or neuroapraxia of the RLN where it ‘hooks’ around the SA (right) or in the vicinity of the arterial ligament (left).
Given these correlations, we searched the clinical data on hoarseness as result of vocal cord dysfunction after cardiac operations in adults.
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2. Methods
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Web-based search in the English language on peer-reviewed publications on vocal paralysis as complication of cardiac surgery: a search of bibliographic databases (Medline (1966–2004) and Embase (1974–2004) was undertaken. The following text and thesaurus terms in combination were employed: hoarseness, vocal cord paralysis, complications, cardiac surgery, and clinical trial. This was performed in conjunction with methodological therapy filters specific to each database.
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3. Results
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3.1. Literature and demographics
Nine relevant clinical reports were identified ranging from reviews to letters and isolated case studies.
Five series [1–5] were identified (Tables 1 and 2) spanning a period of 26 years (January 1979–May 1995) and including 2980 patients (range 68–1471). One is a prospective cohort study [1], the rest are retrospective [2–4]. Two of these [1,2], comprising 750 prospectively and 1471 retrospectively studied patients, were published as letters! In either of two series, 1956 patients underwent coronary (CABG) and 267 valve surgery, while in the remaining three series (759 patients) the nature of surgery was not disclosed (Table 2). The overall incidence of vocal cord injury after adult cardiac surgery was 1.1% (33 in 2980, Table 1).
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Table 2. Nature of adult cardiac procedures in series documenting vocal cord palsy—analysis of five collective reports
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Six more sporadic cases of VCP [6–9] were found between 1997 and 2003. Thirty-nine cases were identified in total.
3.2. Apparent risk factors
There were two: harvesting of internal thoracic arteries and topical cold cardioprotection (ice slush).
In all occasions (22) where vocal cord injury was documented following harvesting of left internal thoracic artery (LITA), it was found ipsilaterally (Tables 3 and 4).
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Table 3. Lateralisation of vocal cord palsy (VCP) and relation to ipsilateral ITA harvesting-analysis of nine reports
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In a unit where topical cold was abandoned, the incidence of the complication decreased from 1.6% (15 in 939) to 0.4% (2 in 532) [2].
In eight cases (Table 5) where left ITA harvesting and topical cold co-existed, the injury was still on the left side (side of the conduit).
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4. Discussion
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Vocal cord injury is a significant, if underreported, complication of adult cardiac surgery [10]. We found the incidence to range between 0.67 and 1.9%.
Although the mechanism cannot always be elicited, the main surgical mechanisms of injury appear to be the increasing harvesting of internal thoracic arteries and the now declining practice of topical cold cardioprotection.
Bilateral ITA harvesting exposes both RLNs to concurrent injury that can be life threatening: there is potential of asphyxiation in bilateral ITA harvesting [11].
Risk management might include optimisation of dissection with avoidance of electrocautery in the proximal ITA pedicle. Beating heart procedures may also hide potential for injury by traction to the RLN whilst positioning the heart.
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References
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- Inada T., Fujise K., Shingu K. Hoarseness after cardiac surgery. J Cardiovasc Surg (Torino) 1998;39(4):455-459.[Medline]
- Shafei H., el-Kholy A., Azmy S., Ebrahim M., al-Ebrahim K. Vocal cord dysfunction after cardiac surgery: an overlooked complication. Eur J Cardiothorac Surg 1997;11:564-566.[Abstract]
- Lederman R.J., Breuer A.C., Hanson M.R., Furlan A.J., Loop F.D., Cosgrove D.M., Estafanous F.G., Greenstreet R.L. Peripheral nervous system complications of coronary artery bypass graft surgery. Ann Neurol 1982;12:297-301.[CrossRef][Medline]
- Schneider B., Bigenzahn W., End A., Denk D.M., Klepetko W. External vocal fold medialization in patients with recurrent nerve paralysis following cardiothoracic surgery. Eur J Cardiothorac Surg 2003;23:477-483.[Abstract/Free Full Text]
- Tewari P., Aggarwal S.K. Combined left-sided recurrent laryngeal and phrenic nerve palsy after coronary artery operation. Ann Thorac Surg 1996;61:1721-1722.[Abstract/Free Full Text]
- Phillips T.G., Green G.E. Left recurrent laryngeal nerve injury following internal mammary artery bypass. Ann Thorac Surg 1987;43:440.[Abstract]
- Horn K.L., Abouav J. Right vocal-cord paralysis after open-heart operation. Ann Thorac Surg 1979;27(4):344-346.[Medline]
- Hamdan A.L., Moukarbel R.V., Farhat F., Obeid M. Vocal cord paralysis after open-heart surgery. Eur J Cardiothorac Surg 2002;21:671-674.[Abstract/Free Full Text]
- Protopapas A.D. Bilateral harvesting of internal thoracic artery for coronary bypass: augmenting the risk for postoperative airway obstruction?. Eur J Cardiothorac Surg 2003;23:137-138.[Free Full Text]
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Abstract
1. Introduction
