Ann Thorac Surg 1996;62:1203-1205
© 1996 The Society of Thoracic Surgeons
Case Report
Warm Heart Operation in a Patient With Myotonic Dystrophy
Tetsuro Sakai, MD,
Shigehito Miki, MD,
Yuichi Ueda, MD,
Takuya Nomoto, MD,
Shuji Hashimoto, MD,
Kazuya Takahashi, MD
Departments of Cardiovascular Surgery and Neurology, Tenri Hospital, Tenri, Nara, Japan
Accepted for publication April 19, 1996.
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Abstract
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Myotonic dystrophy is the most severe form of myotonic disorder. Hypothermia or hyperkalemia may cause generalized muscle contraction during heart operations. We successfully repaired an atrial septal defect and pulmonary stenosis in a patient with myotonic dystrophy using systemic normothermia with continuous normokalemic coronary perfusion. This is the second reported case of a patient with myotonic dystrophy who underwent a cardiac operation.
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Introduction
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Myotonic dystrophy (MD) is a rare and the most severe form of adult muscular dystrophy, inherited as an autosomal dominant trait with a prevalence of 2.4 to 5.5 per 100,000 of the population [1]. Myotonic dystrophy characteristically shows progressive involvement of skeletal muscle and other organs [1]. Recent genetic studies have revealed that the underlying basis of MD is an unstable trinucleotide repeat sequence in a gene encoding a protein kinase family member [2]. Myotonic dystrophy is a well-known hazard in anesthesia for various kinds of operations [3, 4]; however, cardiac operation with the aid of cardiopulmonary bypass in a patient with MD rarely has been reported [5]. We describe a patient with MD who underwent successful repair of an atrial septal defect and pulmonary stenosis. We employed normothermic cardiopulmonary bypass with continuous normokalemic aortic root perfusion on an empty, beating heart to avoid prolonged muscle contraction or possible cardiac dysfunction caused by hypothermia or hyperkalemia.
A 41-year-old woman presented because of easy fatigability. She also complained of muscle weakness of the limb girdle for 2 years. Myotonic dystrophy had been diagnosed in her older sister. The patient showed the classic features of myotonic dystrophy: ptosis, hatchet face, wasted sternocleidomastoid muscles (Fig 1
), nasal speech, peripheral and proximal muscle weakness, and percussion myotonia. Chest auscultation revealed a pansystolic murmur at the second left sternal border with fixed splitting of the second heart sound. Hormonal study showed high serum adrenocorticotrophic hormone level and decreased cortisol level, which indicated mild primary adrenal dysfunction. Echocardiography showed a secundum-type atrial septal defect and valvular pulmonary stenosis. The arterial blood gas analysis in room air demonstrated a pH of 7.414, arterial oxygen tension of 54.3 mm Hg, and arterial carbon dioxide tension of 43.1 mm Hg. On the chest x-ray film, the cardiothoracic ratio was 0.67. Electrocardiography showed an atrial flutter.
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Fig 1. . Postoperative appearance of the patient. Ptosis, sternocleidomastoid muscle atrophy, and temporal and masseter muscle wasting are evident.
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The patient underwent a cardiac operation on May 26, 1995. She was intubated without incident and given thiamylal sodium and vecuronium bromide intravenously. Anesthesia was maintained with fentanyl citrate, midazolam, oxygen, and nitrous dioxide. A standard median sternotomy was made. Cardiopulmonary bypass was established in the usual fashion. The body temperature was maintained at 37°C throughout the operation. The ascending aorta was cross-clamped. Coronary perfusion was maintained with infusion of warm blood through a 12-gauge aortic root cannula (dlp, Inc, Grand Rapids, MI), and the heart was kept beating (Fig 2). The right atrium was opened immediately after the aortic cross-clamping. Patch closure of the atrial septal defect (45 x 20 mm) and pulmonary valve commissurotomy were performed. She was weaned from cardiopulmonary bypass easily.
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Fig 2. . Aortic root perfusion with the blood from a side branch of the arterial line during aortic cross-clamping. A 12-gauge aortic root cannula is placed on the ascending aorta. The heart is kept beating. (Ex. = exchanger.)
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The postoperative course was uneventful except for a mild respiratory tract infection. She was discharged on the 29th postoperative day and has remained well on an outpatient basis for 9 months.
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Comment
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A variety of anesthetic and operative problems have been reported in patients with MD [3, 4]. One of the major concerns is generalized muscle contraction. Administration of depolarizing muscle relaxants or neostigmine, hypothermia and shivering, or raised serum potassium concentration can cause muscle contraction [3, 4, 6]. The membrane of the myotonic or dystrophic myotonic muscle is extremely sensitive to changes in extracellular potassium concentration [6]. The contraction will last for 2 to 3 minutes followed by slow gradual relaxation. The response is unpredictable. Blockade of the neuromuscular junction either with nondepolarizing muscle relaxants or with nerve blocks cannot prevent the muscle contraction because the spasm originates in the abnormal muscle membrane itself [1]. The management of cardiac dysrhythmia is another concern. The heart is involved in a majority of patients with MD. Every conduction pathway can be involved, resulting in sinus bradycardia, atrioventricular block, and bundle-branch block. Generalized myocardial involvement, although not frequent, can cause ventricular dysrhythmia. Sudden death due to heart block or ventricular dysrhythmia has been reported [1].
Reports of cardiac operation in patients with MD have been rare. As far as we know, only 1 case has been reported in the English-language literature. Tanaka and Tanaka [5] reported a 41-year-old man with MD who underwent atrial septal defect closure with the aid of cardiopulmonary bypass.
Theoretically, in cardiac operations in patients with MD, application of systemic hypothermia or hyperkalemic cardioplegia should be avoided as mentioned above. Hypothermia can cause generalized muscle contraction in patients with MD, which is hazardous in performing cardiac operations. Although Tanaka and Tanaka used mild hypothermia (31°C) in their patient with MD without any deleterious effect, application of normothermic cardiopulmonary bypass should be selected. High serum concentration of potassium due to hyperkalemic cardioplegia may also cause muscle contraction. Furthermore, the impact of hyperkalemic cardioplegia on the heart of a patient with MD is not fully understood. Tanaka and Tanaka did not mention their method of myocardial protection.
In our case, for myocardial protection we used continuous normokalemic aortic root perfusion on an empty, beating heart with aortic cross-clamping [7]. The root perfusion can be accomplished either in an empty, beating heart or in a heart with ventricular fibrillation, but the application in the former seems to be better [8]. In this situation, clamping of the ascending aorta has the advantage of avoiding possible air embolism from the beating heart. We also think the connection of the root cannula and the side arm of the arterial line provides stable root pressure. Even if the heart might accidentally eject a large amount of blood during the cross-clamping of the aorta, excessively high pressure to the coronary artery could be avoided with the connection. Although the root perfusion method is less effective in myocardial protection than that with cardioplegia, short-term application of this method is still valuable in some circumstances [7]. During the procedure, it is important to open the right atrium early after aortic cross-clamping for venting to prevent overdistention of the heart.
We think it is mandatory to avoid the use of systemic hypothermia or of hyperkalemic cardioplegia in cardiac operations in patients with MD unless the safety of these methods for patients with MD is fully investigated.
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Footnotes
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Address reprint requests to Dr Sakai, Department of Cardiovascular Surgery, Tenri Hospital, 200 Mishima, Tenri, Nara, Japan 632.
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References
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- Jozefowicz RF, Griggs RC. Myotonic dystrophy. Neurol Clin 1988;6:455–72.[Medline]
- Brook JD, McCurrach ME, Harley HG, et al. Molecular basis of myotonic dystrophy: expansion of a trinucleotide (CTG) repeat at the 3` end of a transcript encoding a protein kinase family member. Cell 1992;68:799–808.[Medline]
- Aldridge LM. Anaesthetic problems in myotonic dystrophy. Br J Anaesth 1985;57:1119–30.[Abstract/Free Full Text]
- O'Shea PJ. Pre-existing nervous system disorders and the safety of anaesthesia. In: Taylor TH, Major E, eds. Hazards and complication of anaesthesia. Edinburgh: Churchill Livingstone, 1987:52–75.
- Tanaka M, Tanaka Y. Cardiac anaesthesia in a patient with myotonic dystrophy. Anaesthesia 1991;46:462–5.[Medline]
- Durelli L, Mutani R, Fassio F, Delsedime M. The effects of the increase of arterial potassium upon the excitability of normal and dystrophic myotonic muscles in man. J Neurol Sci 1982;55:249–57.[Medline]
- Kirklin JW, Barratt-Boyes BG, eds. Cardiac surgery. 2nd ed. New York: Churchill Livingstone, 1993:129–65.
- Buckberg GD, Olinger GN, Mulder DG, Maloney JV Jr. Depressed postoperative cardiac performance. J Thorac Cardiovasc Surg 1975;70:974–88.[Abstract]
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Abstract
Introduction
