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Myotonia dystrophica with A-V dissociation and Stokes-Adams attacks
Myotonia dystrophica A-V dissociation and
with Stokes-Adams
A cuse
of
report
and
review
the
attacks
literature
Narcis J. Petkovich, M.D. Marvin Dunn, M.D.* William Reed, M.D. Kansas City, Kans.
C
ardiac arrhythmias and conduction defects are often noted in patients with myotonia dystrophica. Documented cases of complete atrioventricular dissociation with Stokes-Adams attacks are rare. Litchfield’ described the case of one patient who died from this complication. The etiology of the rhythm disturbances and conduction defects has been controversial. Waring and associate2 suggested that these changes were due to associated coronary atherosclerosis. Fisch and Evans8 and De Wind and Jones4 have presented evidence suggesting that these changes may be due to primary myocardial disease. We recently treated a patient with myatonia dystrophica with Stokes-Adams syndrome due to complete A-V dissociation. An implantable electronic pacemaker was used in the management, providing us with an opportunity to examine the coronary arteries and obtain a myocardial biopsy. Case history This mitted on June health
SO-year-old white married woman was adto the University of Kansas Medical Center 27, 1963. She had been in her usual state of until 3 weeks prior to admission, at which From
the Cardiovascular Laboratory. Department Medical Center, Kansas City, Kans. Received for publication Dec. 2. 1963. *Address: Cardiovasrular Laboratory. University 12, Kans.
391
time she first began to experience-dizziness when standing. Twelve days prior to admission, on June 15, 1963, she experienced two syncopal episodes which were accompanied by grand ma1 convulsions and urinary incontinence. She was taken to the emergencyroom of another hospital and found to have a pulse rate of 20. While in the emergency room, she had two more convulsive episodes, but experienced no further difficulty until she was admitted to the University of Kansas Medical Center for further evaluation. She denied having dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, chest pain, or edema. However, for 4 years she had noted progressive weakness of the lower extremities and a nasal quality to her speech. Her 4%year-old brother, a paternal aunt, and a paternal uncle were all known to have myotonia dystrophica. Her past history was noncontributory, except that a hysterectomy and bilateral oopherectomy had been performed when she was 38 years old. On physical examination she appeared to be quite pale. Her height was 61 inches, and her weight was 96 pounds. She was alert, cooperative, and well oriented, but spoke with a nasal speech. A myopathic facies with receding hairline was noted. The pupils reacted to light and accommodation. No cataracts were noted. A few moist basilar r5les were present. The abdomen was distended, but no organs were palpated. There was some muscle atrophy of the lower extremities. Neurological examination was negative. A myotonic response was elicited from the thumb. The heart was not enlarged to percussion. The first heart sound varied in intensity. The second heart sound was paradoxiof Medicine
of Kansas
Medical
and
Department
Center.
Rainbow
of Surgery,
Blvd.
University
at 39th
of Kansas
St., Kansas
City
392
Petkovich,
Dunn, and Reed
Fig. 1. The ECG shows complete A-V dissociation. The lZO/min. and the \.entricular rate is 66/min, L-cntricular have the appearance of a left bundle branch block.
atria1 rate is compleses
Fig. 2. The ECG shows complete A-V dissociation with an atria1 rate of lOO/min. and a ventricular rate of 34/min. The ventricular complexes in the present tracing have the appearance of those of right bundle branch block, compatible with an idioventricular pacemaker in the left ventricle which is opposite to the focus in Fig. 1.
Myotonia
dysfrofhica,
A- 1’ dissociation
tally split. Atria1 sounds were heard. A Grade 2 systolic ejection murmur was heard at the lower left sternal border. At the time of admission, the blood count, hematocrit, urinalysis, sedimentation rate, serology, blood urea nitrogen, blood sugar, electrolytes, SGOT, total and fractional proteins, bilirubin, and alkaline phosphatase were all within normal limits. The serum cholesterol was 278 mg. per cent, and the total blood lipid was 773 mg. per cent. Electromyographic studies confirmed the diagnosis of myotonia dystrophira. The electrocardiogram (Fig. 1) showed A-V dissociation, with the ventricular complexes having the appearance of those of left bundle branch block. The atrial rate was 120 per minute, and the ventricular rate was about 66 per minute and irregular. She was placed in an intensive-care unit, where her heart rate and rhythm were continuously monitored by an electronic cardiac monitor. Twelve hours after admission she developed ventricular fibrillation. External cardiac massage and artificial respiration were initiated within 2 minutes and the patient was defibrillated by 600-volt A.C. shock. Prior to defibrillation she became comatose, and remained unresponsive after her heart was defibrillated. The pupils were dilated and did not respond to light. An electrode catheter was passed into the right ventricular outflow tract and was used to pace the heart at a rate of 75 per minute. Respiration was maintained by an artitirial respirator.
and Stokes-Adams
attacks
303
She remained comatose, and after 12 hours the catheter electrode and artificial respirator were withdrawn. She was given hydrocortisone, 50 mg. intramuscularly every 6 hours. Intravenous fluids were given for supportive therapy. For the next 72 hours she remained stuporous, responding only by withdrawal from painful stimuli. After this her sensorium gradually cleared and her motor activity gradually returned. By JLIIY 5 (7 days after cardiac arrest), she was able to sit in bed and feed herself. There were no focal neurological defects, but marked impairment of memory was noted. On July 8, she experienced another Stokes-Adams attack, from which she recovered without incident. After this she was given isoproterenol, 5 mg. sublingually four times daily. She was discharged from the hospital on July 17, 1963, at which time she was ambulant, able to read, and moderately alert. Her speech was occasionally inappropriate, and a marked impairment of memory was noted. Her electrocardiogram continued to show complete A-V dissociation. She was seen as an outpatient on July 31, at which time she showed a marked improvement in her mental status. Her rehospitalization was prompted by a syncopal episode on .Aug. 2, 1963. The electrocardiogram (Fig. 2) showed complete A-V dissociation with an atria! rate of 100 per minute and a ventricular rate of 34 per minute. The ventricular complexes had the appearance of those of right bundle branch block, compatible with an idioventricular pacemaker in the left ventricle.
Fig. 3. The ECG shows complete A-V dissociation with an atrial rate of 94/min. and a ventricular rate of 75/min. Each ventricular complex is preceded by an electrical impulse from the implanted pacemaker.
394
Petkovich,
Dunn,
Am. Hcwt J. Sc/&vnber, 1964
and Reed
On August 3, with the patient under general endotracheal anesthesia, a left thoracotomy was performed. Direct inspection by palpation did not reveal evidence of gross coronary atherosclerosis. A Chardack-Greatbatch pacemaker was implanted in the left ventricle near the apex. After implantation of the electrodes, a small segment of myocardium was obtained (.2 by .4 cm.) from the tip of the left ventricle. Seven days postoperatively, it was noted that a segment of skin overlying the power pack was ischemic. She was returned to the operating room on the fourteenth postoperative day, at which time the power pack was moved to another site, and a small flap fashioned to close the original wound. Convalescence was uneventful, and she was dismissed from the hospital on the twenty-first postoperative day, at wh;ch time the electrocardiogram (Fig. 3) showed comolete A-V dissociation with an a‘t r&l rate ’ of 94 per minute and a ventricular rate of 75 per minute. Each ventricular complex was preceded by an electrical impulse from the pacemaker. The ventricular complexes had the appearance of those of right bundle branch block. She was last evaluated on Nov. 19, 1963, at which time she was caring for herself, doing light housework, and cooking. A minimal memory defect persisted. Biopsy findings. The myocardial biopsy (Fig. 4) showed individual muscle bundles separated by loose connective tissue in excess of the normal stroma. Lymphocytes and macrophages were pre-
dominant in the stroma. No area of dense massive scarring was noted. The muscle fibers had rather indistinct borders, a feathery cytoplasm with swelling, and longitudinal separation of myofibrils (Fig. 4). The nuclei were well preserved. The stroma was moderately cellular and contained lymphocytes, macrophages, and fibroblasts. Sections stained with crystal violet and Congo red showed no amyloidlike substance. PAS stain revealed many lipofuscin granules in the myocardial fibers, but also in a number of macrophages of the stroma, suggesting that some myocardial fibers had disintegrated. The iron stains for the same pigment were negative.
Discussion
Myotonia dystrophica is a hereditary disease of the neuromuscular junction described by Steiner@ in 1909. It is characterized by the myotonic reaction of the muscles, dystrophy of the facial and neck muscles as well as the muscles of the lower extremities. Cataracts, frontal baldness, and sterility are other common findings. In 1911, Griffith first called attention to bradycardia in a patient with myotonia dystrophica. Distant heart sounds, splitting of the first sound, low blood pressure, and apical systolic murmurs have been re-
Fig. 4. Myocardial biopsy. Hematoxylin and eosin stain, x2.50. This high-power photomicrograph shows the myocardial muscle fibers to have rather indistinct borders and a feathery cytoplasm with swelling and longitudinal separation of myotibrils. The nuclei are well preserved. The stroma is moderately cellular and contains lymphocytes, macrophages, and fibroblasts.
Myotonia
dystvophica,
A-V dissociation
ported in patients with myotonia dystrophica. (jr7 F&h8 reviewed the electrocardiographic changes in 8.5 patients with myotonia dystrophica and found firstdegree heart block, prolonged QRS duration, and transient atria1 flutter or fibrillation as the most common disturbances. Only 2 patients had second-degree block. Electrocardiographic changes, such as isolated left axis deviation9 and left bundle branch block,‘O have been reported in patients with myotonia dystrophica before the changes in the skeletal muscle became evident. Davies and Evans*1 believed that patients with left axis deviation with deep S waves in Leads II and III had a “fault within the myocardium in the anterolateral aspect of the left ventricle.” They suggested that this abnormal pattern was due to diffuse myocardial scarring. Spurney and Wolf” reported the case of one patient who had had paroxysmal atria1 flutter for 5 years before the skeletal muscular findings of myotonia became evident. Although 8.5 per cent of the patients with myotonia dystrophica have abnormal electrocardiograms, there are only a few reports of A-V dissociation with StokesAdams attacks.8 Litchfieldl reported on one patient with myotonia dystrophica who developed A-V dissociation with Stokes-Adams attacks and subsequently died. An autopsy was not obtained. De Wind and Jones4 found only 3 cases of complete heart block in 98 reported cases with electrocardiographic abnormalities. The reason for the cardiac changes in myotonia dystrophica is unknown. The abnormalities have electrocardiographic been attributed to associated atherosclerosis.2If this were the case, a higher incidence of electrocardiographic abnormalities would be expected in the older age groups. De Wind and Jones4 reviewing 98 cases Of myotonia dystrophica, found that the electrocardiographic abnormalities were as frequent in patients under 45 years of age as in those over 45 years of age. They thought that this would exclude atherosclerosis as the prime cause for the electrocardiographic changes. Payne and Greenfield9 found a similar distribution of electrocardiographic abnormalities in their small series of patients and reached a
and Stokes-Adams
attacks
305
similar collcl usim . The electrocardiographic changes have also been attributed to prolonged vagal stimulation and quinine therapy, but this has not been substantiated clinically.4 The myocardium may be involved in the same degenerative process as the skeletal muscle, but the cardiac changes do not necessarily parallel the changes in skeletal muscle. Atrophy of myocardial fibers and variation in the size and shape of the myocardial nuclei were reported by Black and Ravin.13 In 19.54, Fisch and Evans” reported the autopsy findings in a patient with myotonia dystrophica. The heart showed diffuse fibrosis and separation of myocardial fibers bv dense fibrous tissue. Hypertrophied m&e fibers and rectanguIar nuclei were also noted. The coronary arteries were not atherosclerotic. Although these histologic changes are not pathognomonic of myotonia dystrophia, they have been observed in several autopsied cases, as well as in the myocardial biopsy obtained in this case. Since there was no appreciable coronary atherosclerosis, these ” nonspecific” changes may have been due to the same pathologic process which involved the skeletal muscle. It is possible that these histologic changes may be responsible for the arrhythmias and conduction defects, which, in turn, may cause the sudden, unexpected deaths in patients with myotonia dystrophica. Summary
The case of a patient with myotonia dystrophica who developed atrioventricular dissociation with Stokes-Adams attacks has been presented. Since the StokesAdams attacks were refractory to medical management, an implantable electronic pacemaker was utilized. This offered an opportunity to inspect the heart and obtain a biopsy which showed diffuse fibrosis in the absence of gross coronary artery disease. These tindings lend credence to the concept that the myocardial changes in myotonia dystrophica are not due to associated coronary artery disease. We are indebted to Dr. Ronald Youmans for the electromyographic studies, and to Dr. John I
396
2.
Petkovich,
Waring, J. Studies in tures and 1940. 3. Fisch, C., dystrophia
Am. Heart I. Srptcmbrr, 1964
Dunn, and Reed
J., Ravin, dvstronhia treatment,
A., aud Walker, c. E.: mvotonica: cliuical feaArch. Int. Med. 65:763,
7. Spilhlrle, J. I).: ‘l‘hc heart in ruyotorri~i atrol~llica, Hrit. Heart J. 13:343, 1951. X. Fisch, C.: The heart iii tlystrophi;t iiiyoloiii(x, AM. lir$j\Rr J. 41:523, 1951. 9. I’ayne, C. A., and Greentield, J. C., Jr.: Electrocardiographic abnormalities associated with myotonic dystrophy, AM. HEART J. 65:436,
1963. and Evans, myotonica,
I’. V.: The New England
heart in J. Med.
10.
251:527, 1954. 4. De Wind, L. T., and Jones,
11.
5.
12.
6.
R. J.: Cardiovascular observations in dystrophia myotonica, J.A.M.A. 144:299, 19.50. Steinert, H.: iiber das klinische und anatonische Bild des Muskelschwundes der Myotoniker. Deutsche Ztschr. f. Nervenh. 37:3X, 1909. Evans, W.: The heart in myotonia atrophica, Brit. Heart J. 6:41, 1944.
Kuhn, E.: Eintwicklung eines Linksschenkelblocks bei myotonischer Dystrophie, Schweiz. Med. Wrhnschr. 90:1160, 1960. W.: The signilicance Davies, H., and Evans, of deep S waves in Leads II and III, Brit. Heart J. 22:5.51, 1960. Spurny, O., and Wolf, J.: Prolonged atria1 flutter in myotonic dystrophy, .Am. J. Cardiol.
10:887, 1962. 13. Black, W. C., and Ravin, trophia myotonica. in five cases, Arch.
VII. Path.
A.: Studies in dysAutopsy observations 44:176, 1947.
with Stokes-Adams
A cuse
of
report
and
review
the
attacks
literature
Narcis J. Petkovich, M.D. Marvin Dunn, M.D.* William Reed, M.D. Kansas City, Kans.
C
ardiac arrhythmias and conduction defects are often noted in patients with myotonia dystrophica. Documented cases of complete atrioventricular dissociation with Stokes-Adams attacks are rare. Litchfield’ described the case of one patient who died from this complication. The etiology of the rhythm disturbances and conduction defects has been controversial. Waring and associate2 suggested that these changes were due to associated coronary atherosclerosis. Fisch and Evans8 and De Wind and Jones4 have presented evidence suggesting that these changes may be due to primary myocardial disease. We recently treated a patient with myatonia dystrophica with Stokes-Adams syndrome due to complete A-V dissociation. An implantable electronic pacemaker was used in the management, providing us with an opportunity to examine the coronary arteries and obtain a myocardial biopsy. Case history This mitted on June health
SO-year-old white married woman was adto the University of Kansas Medical Center 27, 1963. She had been in her usual state of until 3 weeks prior to admission, at which From
the Cardiovascular Laboratory. Department Medical Center, Kansas City, Kans. Received for publication Dec. 2. 1963. *Address: Cardiovasrular Laboratory. University 12, Kans.
391
time she first began to experience-dizziness when standing. Twelve days prior to admission, on June 15, 1963, she experienced two syncopal episodes which were accompanied by grand ma1 convulsions and urinary incontinence. She was taken to the emergencyroom of another hospital and found to have a pulse rate of 20. While in the emergency room, she had two more convulsive episodes, but experienced no further difficulty until she was admitted to the University of Kansas Medical Center for further evaluation. She denied having dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, chest pain, or edema. However, for 4 years she had noted progressive weakness of the lower extremities and a nasal quality to her speech. Her 4%year-old brother, a paternal aunt, and a paternal uncle were all known to have myotonia dystrophica. Her past history was noncontributory, except that a hysterectomy and bilateral oopherectomy had been performed when she was 38 years old. On physical examination she appeared to be quite pale. Her height was 61 inches, and her weight was 96 pounds. She was alert, cooperative, and well oriented, but spoke with a nasal speech. A myopathic facies with receding hairline was noted. The pupils reacted to light and accommodation. No cataracts were noted. A few moist basilar r5les were present. The abdomen was distended, but no organs were palpated. There was some muscle atrophy of the lower extremities. Neurological examination was negative. A myotonic response was elicited from the thumb. The heart was not enlarged to percussion. The first heart sound varied in intensity. The second heart sound was paradoxiof Medicine
of Kansas
Medical
and
Department
Center.
Rainbow
of Surgery,
Blvd.
University
at 39th
of Kansas
St., Kansas
City
392
Petkovich,
Dunn, and Reed
Fig. 1. The ECG shows complete A-V dissociation. The lZO/min. and the \.entricular rate is 66/min, L-cntricular have the appearance of a left bundle branch block.
atria1 rate is compleses
Fig. 2. The ECG shows complete A-V dissociation with an atria1 rate of lOO/min. and a ventricular rate of 34/min. The ventricular complexes in the present tracing have the appearance of those of right bundle branch block, compatible with an idioventricular pacemaker in the left ventricle which is opposite to the focus in Fig. 1.
Myotonia
dysfrofhica,
A- 1’ dissociation
tally split. Atria1 sounds were heard. A Grade 2 systolic ejection murmur was heard at the lower left sternal border. At the time of admission, the blood count, hematocrit, urinalysis, sedimentation rate, serology, blood urea nitrogen, blood sugar, electrolytes, SGOT, total and fractional proteins, bilirubin, and alkaline phosphatase were all within normal limits. The serum cholesterol was 278 mg. per cent, and the total blood lipid was 773 mg. per cent. Electromyographic studies confirmed the diagnosis of myotonia dystrophira. The electrocardiogram (Fig. 1) showed A-V dissociation, with the ventricular complexes having the appearance of those of left bundle branch block. The atrial rate was 120 per minute, and the ventricular rate was about 66 per minute and irregular. She was placed in an intensive-care unit, where her heart rate and rhythm were continuously monitored by an electronic cardiac monitor. Twelve hours after admission she developed ventricular fibrillation. External cardiac massage and artificial respiration were initiated within 2 minutes and the patient was defibrillated by 600-volt A.C. shock. Prior to defibrillation she became comatose, and remained unresponsive after her heart was defibrillated. The pupils were dilated and did not respond to light. An electrode catheter was passed into the right ventricular outflow tract and was used to pace the heart at a rate of 75 per minute. Respiration was maintained by an artitirial respirator.
and Stokes-Adams
attacks
303
She remained comatose, and after 12 hours the catheter electrode and artificial respirator were withdrawn. She was given hydrocortisone, 50 mg. intramuscularly every 6 hours. Intravenous fluids were given for supportive therapy. For the next 72 hours she remained stuporous, responding only by withdrawal from painful stimuli. After this her sensorium gradually cleared and her motor activity gradually returned. By JLIIY 5 (7 days after cardiac arrest), she was able to sit in bed and feed herself. There were no focal neurological defects, but marked impairment of memory was noted. On July 8, she experienced another Stokes-Adams attack, from which she recovered without incident. After this she was given isoproterenol, 5 mg. sublingually four times daily. She was discharged from the hospital on July 17, 1963, at which time she was ambulant, able to read, and moderately alert. Her speech was occasionally inappropriate, and a marked impairment of memory was noted. Her electrocardiogram continued to show complete A-V dissociation. She was seen as an outpatient on July 31, at which time she showed a marked improvement in her mental status. Her rehospitalization was prompted by a syncopal episode on .Aug. 2, 1963. The electrocardiogram (Fig. 2) showed complete A-V dissociation with an atria! rate of 100 per minute and a ventricular rate of 34 per minute. The ventricular complexes had the appearance of those of right bundle branch block, compatible with an idioventricular pacemaker in the left ventricle.
Fig. 3. The ECG shows complete A-V dissociation with an atrial rate of 94/min. and a ventricular rate of 75/min. Each ventricular complex is preceded by an electrical impulse from the implanted pacemaker.
394
Petkovich,
Dunn,
Am. Hcwt J. Sc/&vnber, 1964
and Reed
On August 3, with the patient under general endotracheal anesthesia, a left thoracotomy was performed. Direct inspection by palpation did not reveal evidence of gross coronary atherosclerosis. A Chardack-Greatbatch pacemaker was implanted in the left ventricle near the apex. After implantation of the electrodes, a small segment of myocardium was obtained (.2 by .4 cm.) from the tip of the left ventricle. Seven days postoperatively, it was noted that a segment of skin overlying the power pack was ischemic. She was returned to the operating room on the fourteenth postoperative day, at which time the power pack was moved to another site, and a small flap fashioned to close the original wound. Convalescence was uneventful, and she was dismissed from the hospital on the twenty-first postoperative day, at wh;ch time the electrocardiogram (Fig. 3) showed comolete A-V dissociation with an a‘t r&l rate ’ of 94 per minute and a ventricular rate of 75 per minute. Each ventricular complex was preceded by an electrical impulse from the pacemaker. The ventricular complexes had the appearance of those of right bundle branch block. She was last evaluated on Nov. 19, 1963, at which time she was caring for herself, doing light housework, and cooking. A minimal memory defect persisted. Biopsy findings. The myocardial biopsy (Fig. 4) showed individual muscle bundles separated by loose connective tissue in excess of the normal stroma. Lymphocytes and macrophages were pre-
dominant in the stroma. No area of dense massive scarring was noted. The muscle fibers had rather indistinct borders, a feathery cytoplasm with swelling, and longitudinal separation of myofibrils (Fig. 4). The nuclei were well preserved. The stroma was moderately cellular and contained lymphocytes, macrophages, and fibroblasts. Sections stained with crystal violet and Congo red showed no amyloidlike substance. PAS stain revealed many lipofuscin granules in the myocardial fibers, but also in a number of macrophages of the stroma, suggesting that some myocardial fibers had disintegrated. The iron stains for the same pigment were negative.
Discussion
Myotonia dystrophica is a hereditary disease of the neuromuscular junction described by Steiner@ in 1909. It is characterized by the myotonic reaction of the muscles, dystrophy of the facial and neck muscles as well as the muscles of the lower extremities. Cataracts, frontal baldness, and sterility are other common findings. In 1911, Griffith first called attention to bradycardia in a patient with myotonia dystrophica. Distant heart sounds, splitting of the first sound, low blood pressure, and apical systolic murmurs have been re-
Fig. 4. Myocardial biopsy. Hematoxylin and eosin stain, x2.50. This high-power photomicrograph shows the myocardial muscle fibers to have rather indistinct borders and a feathery cytoplasm with swelling and longitudinal separation of myotibrils. The nuclei are well preserved. The stroma is moderately cellular and contains lymphocytes, macrophages, and fibroblasts.
Myotonia
dystvophica,
A-V dissociation
ported in patients with myotonia dystrophica. (jr7 F&h8 reviewed the electrocardiographic changes in 8.5 patients with myotonia dystrophica and found firstdegree heart block, prolonged QRS duration, and transient atria1 flutter or fibrillation as the most common disturbances. Only 2 patients had second-degree block. Electrocardiographic changes, such as isolated left axis deviation9 and left bundle branch block,‘O have been reported in patients with myotonia dystrophica before the changes in the skeletal muscle became evident. Davies and Evans*1 believed that patients with left axis deviation with deep S waves in Leads II and III had a “fault within the myocardium in the anterolateral aspect of the left ventricle.” They suggested that this abnormal pattern was due to diffuse myocardial scarring. Spurney and Wolf” reported the case of one patient who had had paroxysmal atria1 flutter for 5 years before the skeletal muscular findings of myotonia became evident. Although 8.5 per cent of the patients with myotonia dystrophica have abnormal electrocardiograms, there are only a few reports of A-V dissociation with StokesAdams attacks.8 Litchfieldl reported on one patient with myotonia dystrophica who developed A-V dissociation with Stokes-Adams attacks and subsequently died. An autopsy was not obtained. De Wind and Jones4 found only 3 cases of complete heart block in 98 reported cases with electrocardiographic abnormalities. The reason for the cardiac changes in myotonia dystrophica is unknown. The abnormalities have electrocardiographic been attributed to associated atherosclerosis.2If this were the case, a higher incidence of electrocardiographic abnormalities would be expected in the older age groups. De Wind and Jones4 reviewing 98 cases Of myotonia dystrophica, found that the electrocardiographic abnormalities were as frequent in patients under 45 years of age as in those over 45 years of age. They thought that this would exclude atherosclerosis as the prime cause for the electrocardiographic changes. Payne and Greenfield9 found a similar distribution of electrocardiographic abnormalities in their small series of patients and reached a
and Stokes-Adams
attacks
305
similar collcl usim . The electrocardiographic changes have also been attributed to prolonged vagal stimulation and quinine therapy, but this has not been substantiated clinically.4 The myocardium may be involved in the same degenerative process as the skeletal muscle, but the cardiac changes do not necessarily parallel the changes in skeletal muscle. Atrophy of myocardial fibers and variation in the size and shape of the myocardial nuclei were reported by Black and Ravin.13 In 19.54, Fisch and Evans” reported the autopsy findings in a patient with myotonia dystrophica. The heart showed diffuse fibrosis and separation of myocardial fibers bv dense fibrous tissue. Hypertrophied m&e fibers and rectanguIar nuclei were also noted. The coronary arteries were not atherosclerotic. Although these histologic changes are not pathognomonic of myotonia dystrophia, they have been observed in several autopsied cases, as well as in the myocardial biopsy obtained in this case. Since there was no appreciable coronary atherosclerosis, these ” nonspecific” changes may have been due to the same pathologic process which involved the skeletal muscle. It is possible that these histologic changes may be responsible for the arrhythmias and conduction defects, which, in turn, may cause the sudden, unexpected deaths in patients with myotonia dystrophica. Summary
The case of a patient with myotonia dystrophica who developed atrioventricular dissociation with Stokes-Adams attacks has been presented. Since the StokesAdams attacks were refractory to medical management, an implantable electronic pacemaker was utilized. This offered an opportunity to inspect the heart and obtain a biopsy which showed diffuse fibrosis in the absence of gross coronary artery disease. These tindings lend credence to the concept that the myocardial changes in myotonia dystrophica are not due to associated coronary artery disease. We are indebted to Dr. Ronald Youmans for the electromyographic studies, and to Dr. John I
396
2.
Petkovich,
Waring, J. Studies in tures and 1940. 3. Fisch, C., dystrophia
Am. Heart I. Srptcmbrr, 1964
Dunn, and Reed
J., Ravin, dvstronhia treatment,
A., aud Walker, c. E.: mvotonica: cliuical feaArch. Int. Med. 65:763,
7. Spilhlrle, J. I).: ‘l‘hc heart in ruyotorri~i atrol~llica, Hrit. Heart J. 13:343, 1951. X. Fisch, C.: The heart iii tlystrophi;t iiiyoloiii(x, AM. lir$j\Rr J. 41:523, 1951. 9. I’ayne, C. A., and Greentield, J. C., Jr.: Electrocardiographic abnormalities associated with myotonic dystrophy, AM. HEART J. 65:436,
1963. and Evans, myotonica,
I’. V.: The New England
heart in J. Med.
10.
251:527, 1954. 4. De Wind, L. T., and Jones,
11.
5.
12.
6.
R. J.: Cardiovascular observations in dystrophia myotonica, J.A.M.A. 144:299, 19.50. Steinert, H.: iiber das klinische und anatonische Bild des Muskelschwundes der Myotoniker. Deutsche Ztschr. f. Nervenh. 37:3X, 1909. Evans, W.: The heart in myotonia atrophica, Brit. Heart J. 6:41, 1944.
Kuhn, E.: Eintwicklung eines Linksschenkelblocks bei myotonischer Dystrophie, Schweiz. Med. Wrhnschr. 90:1160, 1960. W.: The signilicance Davies, H., and Evans, of deep S waves in Leads II and III, Brit. Heart J. 22:5.51, 1960. Spurny, O., and Wolf, J.: Prolonged atria1 flutter in myotonic dystrophy, .Am. J. Cardiol.
10:887, 1962. 13. Black, W. C., and Ravin, trophia myotonica. in five cases, Arch.
VII. Path.
A.: Studies in dysAutopsy observations 44:176, 1947.