Mitochondrial Encephalomyopathy (Kearns-Sayre Syndrome) With Complete Atrioventricular Block

Abstract

pacemaker was implanted into a 17-year-old male patient with mitochondrial encephalomyopathy (Kearns-Sayre syndrome) accompanied by cardiac failure due to complete atrioventricular block. We discuss several clinical problems relevant to this case, such as the patient's age, physique, cardiac disorder, and the prognosis for this syndrome. Case ReportThe patient was a 17-year-old male who experienced shortness of breath upon exertion due to bradycardia. The patient had developmental delays beginning at age 2, bilateral ptosis due to external ophthalmoplegia from 11 years of age and mitochondrial myopathy from 13 years of age. His visual power was diminished by atypical retinal pigmentation from 14 years of age, and bradycardia was apparent from 15 years of age. At 17 years of age, he visited hospital as an outpatient with cardiac failure resulting from the bradycardia. At the first examination, he was 129 cm tall and weighed 22.5 kg. His heart rate was 32 beats/min and his blood pressure was 126/50 mmHg. He was suffering from bilateral ptosis, decreased visual power, mental retardation, and microsthenic arms and legs. An electrocardiogram (ECG) on admission showed complete atrioventricular block in which the ventricular rate was 31 beats/min and there was right axial deviation, negative T waves in III and aVF, giant negative T waves in V1-V3, and prolongation of QT (QTc = 0.49) (Fig 1). Chest roentgenogram showed a cardiothoracic ratio (CTR) of 53% (Fig 2).Echocardiogram showed no hypertrophy and a normally functioning left ventricle. No pericardial effusion was detected (Fig 3). His illness was diagnosed as mitochondrial encephalomyopathy (Kearns-Sayre syndrome). According to the pediatricians and neurologists, further physical development of the patient could not be expected and after considering the patient's prognosis, we decided to implant a permanent pacemaker. The pacemaker (Medtronic Minuet 7108) was implanted on the major pectoral muscle and the operation mode was set to DDD 70 ppm (Fig 4). One year after implantation, the CTR decreased to 45% and cardiac failure was alleviated (Fig 5). DiscussionKearns-Sayre syndrome is regarded as a type of mitochondrial encephalomyopathy accompanied with mitochondrial DNA abnormality of the muscle. 1,2 The diagnosis of this disease is based upon the 3 chief symptoms (ie progressive external ophthalmoplegia, atypical retinal pigmentation and cardiac conduction block) together with a morphological abnormality of the mitochondria in the skeletal muscle observed on biopsy (ragged red fibers are observed with the Gomori-trichrome stain under a light microscope). 3,4 Although a skeletal muscle biopsy was not performed in the present case, the patient's disease is certainly a typical mitochondrial encephalopathy with the 3 chief symptoms of Kearns-Sayre syndrome.The characteristic cardiac abnormality of Kearns-Sayre syndrome is the development of morphologically abnormal mitochondria in myocardial cells at a high rate before the onset of an abnormal ECG or decreased power of ...

Torsades de Pointes in a Patient with Kearns‐Sayre Syndrome: A Fortunate Finding

“…KSS is a mitochondrial encephalomyopathy caused by abnormalities of mitochondrial DNA 3 and is typically associated with cardiac conduction defects. [3][4][5][6][7][8] KSS has also been associated with cardiac failure. 2 Patients with KSS who experience syncope are presumed to have underlying heart block.…”

Strokes in mitochondrial diseases

“…Отмечаются задержка физического и полового развития, ихтиоз с очагами гиперпигментации, вальгусная девиация голеней и высокий свод стопы. Нарушения со стороны эндокринной системы -дефицит гормона роста, гипогонадизм, сахарный диабет, гипопаратиреоз, наруше-ние адреналового обмена [63,66,[72][73][74][75][76][77][78][79][80].…”

“…Пониманию природы синдрома способствовали молекулярно-генетиче-ские исследования и обнаружение мутаций митохондриаль-ной ДНК [63][64][65]. При синдроме Кернса-Сейра идентифи-цировано несколько типов мутаций мтДНК: крупные пере-стройки мтДНК -«общая делеция» (r-мутации), точковые мутации мтДНК-тРНК (syn-мутации), а также дуплекция мтДНК [63,[66][67][68][69]. Впервые гистохимические и ультра-…”

Mitochondrial cardiomyopathies

“…Полная атриовентрикулярная блокада приводит к миокардиальной дисфункции с последующим возможным развитием недостаточности кровообращения [36]. Высокий риск миокардиальной недостаточности на фоне полного атриовентрикулярного блока диктует необходимость имплантации пейсмекера типа DDD в ранние сроки, до появления жизнеугрожающих нарушений в проводящей системе сердца [37,38].…”