hypertrophic cardiomyopathy associated mitochondrial ... · brheart 7 1985; 54: 543-7 hypertrophic...

Br Heart 7 1985; 54: 543-7

Hypertrophic cardiomyopathy associated with a

mitochondrial myopathy of voluntary muscles andcongenital cataract

R C A SENGERS,* A M STADHOUDERS,t E VAN LAKWIJK-VONDROVICOVA,tK KUBAT,§ W RUITENBEEK*

From the Departments of *Paediatrics, tSubmicroscopic Morphology, ICardiology, and §Pathology,University of Nijmegen, Nijmegen, The Netherlands

SUMMARY Structurally abnormal mitochondria were found in skeletal muscle cells from a woman

with hypertrophic cardiomyopathy and myopathy ofvoluntary muscles associated with congenitalcataracts. Moderate exercise resulted in lactic acidosis. Oxidation ofpyruvate and other substratesand the production of adenosine triphosphate were normal in vitro. A younger brother of thepatient had had congenital cataract and had died from hypertrophic obstructive cardiomyopathy.

The concurrent occurrence of pathological changesin both heart and skeletal muscle is a feature ofseveral inherited diseases such as Duchenne andBecker muscular dystrophies. The heart and volun-tary muscles are also both affected in several diseaseswith a well defined enzyme deficiency, such asPompe's disease, and in other diseases in which themolecular defect is unknown.Ten years ago we described seven patients from

three unrelated families who had hypertrophic car-diomyopathy and a mitochondrial myopathy of skel-etal muscle.' They had associated symptoms of con-genital cataracts and exercise related lactic acidosis.The syndrome is now registered as an inherited dis-ease 21235 on the McKusick register.2 Recently wehad the opportunity to study two other patients fromone family who had this syndrome. On this occasionwe are able to perform biochemical studies on skele-tal muscle tissue from one of the patients.

Case reports

PATIENT 1This woman of 33 was the third of five children ofhealthy non-consanguineous parents. Within a fewweeks of birth, bilateral cataracts were identified.These were surgically removed when she was 6months old. She always became very tired during

Requests for reprints to Dr RCA Sengers, Department of Pae-diatrics, University ofNijmegen, PO Box 9101, 6500 HB Nijmegen,The Netherlands.

Accepted for publication 12 July 1985

exercise and she could never compete physically withher peers. At the age of 25 years she was first admit-ted to our hospital for cardiological examinationbecause her brother had died from a cardio-myopathy. Her other sibs were healthy. She wasknown to have had a heart murmur for about 20years. Her exercise tolerance worsened with activity,but did not change consistently with time of day,food intake, or menstrual cycle. She deniedprogression of her exercise intolerance, and also hadno dysarthria, dysphagia, diplopia, muscle cramps,fasciculations, or myotonia. She did not drink alco-hol to excess or take drugs, other than the occasionalaspirin. General examination at the age of 33 yearswas unremarkable except for moderate obesity(height 160 cm, weight 50 kg). She was visuallyhandicapped by aphakia. Her mental state, cranialnerve function, muscle bulk and tone, tendonreflexes, sensation, and coordination were normal.Muscle strength during individual movements wasnormal but her endurance was extremely limited.Cardiological examination showed cardiomegaly anda grade II systolic murmur at the left sternal border.Blood pressure was 120/70 mm Hg. There was elec-trocardiographic evidence of hypertrophy of theright and left ventricles (Fig. 1) and apical hyper-trophic cardiomyopathy was diagnosed by echo-cardiography. The interventricular septum mea-sured 16 mm and the posterior left ventricular wall13 mm at the level of the mitral valve. The wall andseptum were both 18 mm thick at the apex. Dopplerstudies did not show flow velocity abnormalities.During exercise testing on a bicycle ergometer she

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Fig. 1 Electrocardiogram in patient I showing evidence of hypertrophy of the right and left ventricles.

was not able to perform at the 40 W level for morethan a few minutes before she became exhausted.Laboratory examination showed a normal arterialpH and lactic acid concentration at rest but a seriousmetabolic acidosis (pH, 7-28; bicarbonate 15-4mmol/l; base excess, -99 mmol/l) and raised lacticacid concentration (10-4 mmol/l, normal < 1-8mmol/l) after submaximal exercise. Lactic acid con-centration after 5 minutes' exercise on a treadmill ata speed of 2 miles per hour (3-2 km per hour) and aninclination of 10% increased by 3-6 mmol/l and pHfell from 7-37 to 7-22. (There were no changes incontrols). Serum creatine kinase concentration wasnormal. Maximum heart rate was 140 beats per min.A specimen of the patient's quadriceps muscle wasobtained by open biopsy after she had giveninformed consent.

PATIENT 2A younger brother of patient 1 was admitted to ourclinic at the age of 18 years with cardiomegaly. At theage of 5 years he also had had congenital cataractsremoved. He suffered from exercise intolerance.General examination revealed no severe abnormal-ities. Blood pressure was 135/80 mm Hg. A chest xray examination showed cardiomegaly and a grade IIsystolic murmur was heard at the left sternal border

and in the second right intercostal space. Hyper-trophy ofthe left ventricle and of the interventricularseptum was diagnosed by electrocardiography andvector cardiography. Heart catheterisation showednormal pressures. The tip of the catheter, however,could not be placed in the most distal part of the leftventricle. The cineangiographic findings were typi-cal of hypertrophic obstructive cardiomyopathy.Subjectively he remained well until he was 23 yearsold when he was readmitted with an attack of cardiacasthma. He responded well to conventional treat-ment. Shortly afterwards, however, cardiac asthmadeveloped again and he died. The most importantfinding at necropsy was myocardial hypertrophy.The heart weighed 1220 g. Hypertrophy of the sep-tum and the left ventricle had seriously narrowed theoutflow tract. The right ventricle was also hyper-trophied. The heart valves were intact and therewere no defects in the atrial or ventricular septa. Thecoronary arteries were normal.

HI STOPATHOLOGICAL EXAMINATIONSkeletal muscleMuscle fibres from patient 1 did not vary greatly insize or shape. No necrotic fibres were seen and therewas no inflammation. Connective tissue, nerve bun-dles, and blood vessels were normal. Haematoxylin



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Fig. 2 Various mitochondrial abnormalities seen in a biopsy specimen of the quadriceps muscle from patient 1.(a) Low power photomicrograph of a transversely sectioned muscle fibre stained by means of the succinic dehydrogenasereaction to show the mitochondria. Note the strong staining of the subsarcolemmas of most muscle fibres. No ragged redfibres were seen. Original magnification, x 270. (b) Low power electron micrograph of subsarcolemmal area showingpoorly developed cristae in mitochondria and electron dense matrix deposits. Original magnification, x 22 000. (c) Highpower electron micrograph of giant mitochondrion with crystalline and amorphous inclusions. Original magnification,x 93 000. (d) Electronmicrograph showing histochemical reaction to cytochrome oxidase by aberrant subsarcolemmal mito-chondria. Original magnification, x 18 000.

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Fig. 3 Photomicrographs of myocardial fibres from patient2. (a) Disarrayed myocardial fibres of type IIA and IIB(according to Maron4) in the septum. Elastin trichromeMasson stain. Original magnification, x 35. (b)Myofibrillolysis and vacuolar dystrophy of severely hyper-trophic muscle fibres with pericellular fibrosis. These are

small scars in left upper and lower corner. Elastin trichromeMasson stain. Original magnification, x 350. (c) Laminarscar seen in the middle third of the ventricular septum.Elastin trichrome Masson stain. Original magnification,x 35.

and eosin stained sections showed that most of themuscle fibres contained an increased amount of blu-ish red granular material in the subsarcolemmalregions. In preparations stained by the modifiedGomori trichrome technique red granular materialwas seen beneath the sarcolemma in numerousfibres, but there were no distinct "ragged red" fibres.The number of lipid droplets between the

myofibrils and under the sarcolemmal membraneswas increased. Periodic acid/Schiff staining showedthat fibres with high lipid content also containedincreased amounts of glycogen. There was no cor-relation, however, between lipid and glycogen stor-age and the intensity of the trichrome red staining.There was a slight predominance of type I adenosinetriphosphatase reactions but in other respects a nor-mal checkerboard pattern of the distribution of fibretypes was seen. There was a pronounced increase inthe amount of reaction product within individualfibres when succinic dehydrogenase and NADH-tetrazolium reductase were used to stain for mito-chondria (Fig. 2a).Electronmicroscopy showed a considerable dis-

turbance of the contractile apparatus with dilatationof intermyofibrillar spaces, splitting of myofibrils,and loss of the concerted arrangement of sarcomeresin many muscle fibres. More serious, however, wasthe great increase in aberrant mitochondria. Many ofthe intermyofibrillar and subsarcolemmal mito-chondria did not have cristae of normal appearanceand arrangement. Also they often contained cristal-like inclusions and osmiophilic deposits of variablesize and density (Fig. 2b and c). Quantitativemorphometric stereological studies3 (ratio (SE))confirmed that there was a distinct increase in thevolume density (volume fraction occupied by thecomponent) of the mitochondrial compartment(8 46, normal 4-28 (1V84)) and of the lipid (1-79,normal 0 79 (0 50)) and glycogen (3-11, normal 1 19(0 87)) deposits when compared with results inuntrained age matched controls. Enzymehisto-chemistry showed normal activity of cytochromeoxidase (Fig. 2d). Unfortunately, no skeletal musclefrom patient 2 was available for examination.

The heart (patient 2)The myocardial fibres varied in size and shape andsome were in considerable disarray (Fig. 3a) (typeIIA and IIB by Maron and Roberts's classification4).Many of them contained vacuoles and showedmyofibrillolysis. There were multiple scattered smallscars in the myocardium of the left ventricle (Fig.3b), moreover a broad laminal fibrosis was found inthe middle third of the septum (Fig. 3c), while theportions of the septum adjacent the right and leftventricle were spared. A small deparaffinised myo-

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cardial specimen was postfixed in glutaraldehydeand examined by electron microscopy. Despite arte-facts due to paraffin embedding, myofibrils wereclearly recognisable. There was a great increase inmitochondria throughout the myocardial fibres. Thesize of the mitochondria varied greatly, many con-tained large osmiophilic inclusions, apparently iden-tical to those seen in the skeletal muscle mito-chondria from patient 1.

Biochemical examinationRates ofpyruvate and malate oxidation in the musclehomogenate were assayed by the method of Book-elman et al5 with the glucose hexokinase systembeing replaced by 20 mmol/l creatine.P',P5-di(adenosine-5'-) pentaphosphate (Ap5A) wasadded to inhibit adenylate kinase activity.6 Ade-nosine triphosphate production rates were deter-mined in the presence of Ap5A and corrected forarsenite insensitivity.6 Cytochromes were assayed bythe method of Bookelman et al.7 Carnitine was esti-mated by the method of Parvin and Pande.8

Biochemical examination did not show a clear cutdefect in the energy producing pathway of the mito-chondria. The cytochromes were present in normalamounts. Concentrations of total and non-esterifiedcarnitine were normal in serum and muscle homoge-nates.

Discussion

Our patients and those described before' probablyhad a hereditary disease of heart and skeletal muscleassociated with congenital cataracts. On the basis ofpathophysiological criteria the cardiomyopathy canbe classified as a hypertrophic cardiomyopathy. Inthe patient who died the gross pattern of the heartwas characteristic of this type of cardiomyopathy.The broad scar in the septum, however, was anunusual finding. It can only be supposed that itdeveloped because of a concurrent disturbance ofcoronary perfusion in the severely hypertrophicmyocardium.Pronounced changes in the ultrastructure and dis-

tribution of mitochondria in the myocardial andskeletal muscle fibres were the most prominent his-topathological findings. There are several reports ofmitochondrial abnormalities in the skeletal musclesof patients with a heart disease.9- 1lA functional abnormality is likely in patient 1

because there was abnormally high lactic acidosisafter exercise as a consequence of impaired pyruvateoxidation. Biochemical examination of muscle tis-sue, however, excluded the well known causes ofdisordered pyruvate oxidation. A disturbance ofoxygen delivery to the mitochondria might explain

the disordered mitochondrial function.Unfortunately we did not test for oxygen availabilityin vivo. Impaired oxygen delivery might also explainthe occurrence of congenital cataract since the lens isvascularised for only a limited time during fetaldevelopment. Impaired oxygen delivery can causecataract in experimental studies.12Although we know of several patients with this

syndrome in The Netherlands, no other cases havebeen described in published reports. We know of afew more Swiss patients with the syndrome (B Stein-man, personal communication). The frequency ofsuch cases is probably greater than the small numberof reported cases suggests.

References

1 Sengers RCA, Ter Haar BGA, Trijbels JMF, Willems JH,Daniels 0, Stadhouders AM. Congenital cataract and mito-chondrial myopathy of skeletal and heart muscle associated withlactic acidosis after exercise. J Pediatr 1975; 86: 873-80.

2 McKusick VA. Mendelian inheritance in man. 6th ed. Baltimore:John Hopkins University Press, 1983.

3 Weibel ER. Stereological methods. Vol. 1: Practical methods forbiological morphometry. London: Academic Press, 1979.

4 Maron BJ, Roberts WC. Quantitative analysis ofcardiac musclecell disorganization in the ventricular septum of patients withhypertrophic cardiomyopathy. Circulation 1979; 59: 689-706.

5 Bookelman H, Trijbels JMF, Sengers RCA, Janssen AJM,Veerkamp JH, Stadhouders AM. Pyruvate oxidation in rat andhuman skeletal muscle mitochondria. Biochem Med 1978; 20:395-403.

6 Ruitenbeek W, Janssen AJM, Fischer JC, Sengers RCA, Tri-jbels JMF, Stadhouders AM. Investigation of the energymetabolism in diseased human muscular tissue. In: Scarlato G,Cerri C, eds. Mitochondrial pathology in muscle diseases. Padua:Piccin Nuova Libraria, 1983: 197-201.

7 Bookelman H, Trijbels JMF, Sengers RCA, Janssen AJM.Measurement of cytochromes in human skeletal muscle mito-chondria, isolated from fresh and frozen stored muscle speci-mens. Biochem Med 1978; 19: 366-73.

8 Parvin R, Pande SV. Microdetermination of (-)carnitine and carnitine acetyltransferase activity. Anal Biochem1977; 79: 190-201.

9 Bogousslavsky J, Perentes E, Deruaz JP, Regli F. Mito-chondrial myopathy and cardiomyopathy with neuro-

degenerative features and multiple brain infarcts. J Neurol Sci1982; 55: 351-7.

10 Hubner G, Grantzow R. Mitochondrial cardiomyopathy withinvolvement of skeletal muscles. Virchows Arch [A] 1983; 399:115-25.

11 Mastaglia FL, Thompson PL, Papadimitriou JM. Mito-chondrial myopathy with cardiomyopathy, lactic acidosis andresponse to prednisone and thiamine. Aust NZJ Med 1980; 10:660-4.

12 Varma SD, Chand D, Sharma YR, Kuck JF Jr, Richards RD.Oxidative stress on lens and cataract formation: role of light andoxygen. Curr Eye Res 1984; 3: 35-57.

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