1/707. C-terminal HERG mutations: the role of hypokalemia and a KCNQ1-associated mutation in cardiac event occurrence. BACKGROUND: The long-QT syndrome (LQTS) is a genetically heterogeneous disease in which 4 genes encoding ion-channel subunits have been identified. Most of the mutations have been determined in the transmembrane domains of the cardiac potassium channel genes KCNQ1 and HERG. In this study, we investigated the 3' part of HERG for mutations. methods AND RESULTS: New specific primers allowed the amplification of the 3' part of HERG, the identification of 2 missense mutations, S818L and V822 M, in the putative cyclic nucleotide binding domain, and a 1-bp insertion, 3108 1G. hypokalemia was a triggering factor for torsade de pointes in 2 of the probands of these families. Lastly, in a large family, a maternally inherited G to A transition was found in the splicing donor consensus site of HERG, 2592 1G-A, and a paternally inherited mutation, A341E, was identified in KCNQ1. The 2 more severely affected sisters bore both mutations. CONCLUSIONS: The discovery of mutations in the C-terminal part of HERG emphasizes that this region plays a significant role in cardiac repolarization. Clinical data suggests that these mutations may be less malignant than mutations occurring in the pore region, but they can become clinically significant in cases of hypokalemia. The first description of 2 patients with double heterozygosity associated with a dramatic malignant phenotype implies that genetic analysis of severely affected young patients should include an investigation for >1 mutation in the LQT genes. ( info) |
2/707. Renal tubular acidosis, hypokalemic paralysis, rhabdomyolysis, and acute renal failure--a rare presentation of Chinese herbal nephropathy. We encountered a 66-year-old Chinese man presented with hypokalemic paralysis, rhabdomyolysis and acute renal failure after administration of mixed Chinese herbs. Proximal renal tubular acidosis and selective glucosuria were the main tubular dysfunctions. The renal failure recovered smoothly and rapidly after resuscitation and the tubular function abnormalities regained spontaneously after medicine withdrawal. It should be recognized that renal tubular acidosis with hypokalemic paralysis, rhabdomyolysis and subsequent acute renal failure may develop after taking Chinese mixed herbal medicine. ( info) |
3/707. Hypokalemic myopathy due to chronic alcoholism. A patient with hypokalemic myopathy occurring in the context of chronic alcoholism was reported. A 56-year-old male patient, heavy drinker for 20 years, complained of marked weakness and acutely developing pains in his limbs. The principal clinical findings were weakness and tenderness of the proximal limbs and girdle muscle. He was unable to lift his head or any extremities from the bed. Deep tendon reflexes were diminished, but not absent. There was no sensory disturbance except for muscle tenderness. These clinical manifestations disappeared gradually by abstinence from drinking, and potassium administration therapy, and the patient recovered completely on the 26th day after onset. On the day after admission (8th day), serum potassium value was 2.2mEq/L, and serum CPK activity was 4270IU. The ECG pattern was consistent with a diagnosis of low potassium content in serum, and the EMG pattern was consistent with a diagnosis of myopathy. These electrophysiological findings had a tendency to recover from this pattern to normal range correspondingly with clinical improvement. The repeated muscle biopsies showed that vacuolation, hyaline degeneration and significant phagocyte infiltration were observed in the muscle on the 9th day after the onset of muscle weakness, and that these pathological findings disappeared almost completely three weeks later. The frequently repeated examinations of potassium content and CPK activity in sera showed that there was a close correlation between these biochemical abnormalities and clinical improvememt. The pathogenesis of alcoholic myopathy and significance of CPK abnormality in chronic alcoholism were discussed. ( info) |
4/707. life-threatening ventricular tachycardia due to liquorice-induced hypokalaemia. We report on a patient with hypokalaemia and severe ventricular tachycardia of torsades de pointes type which turned out to be caused by an apparent mineralocorticoid excess syndrome associated with liquorice consumption. The patient, a 44-year-old woman, attended the hospital because of irregular heart rhythm and she displayed repeated episodes of life-threatening torsades de pointes ventricular tachycardia. The initial serum potassium was low: 2.3 mmol L-1. The patient was treated with potassium and magnesium infusions, and the dysrhythmias eventually ceased. Endocrinological investigations showed no indication of Cushing's syndrome or hyperaldosteronism. After some time it became clear that the patient had ingested moderately large amounts of liquorice every day for 4 months. After the patient stopped this habit the hypokalaemia and dysrhythmias did not recur and after more than 1 year there are no signs of cardiac illness. ( info) |
5/707. Hypokalemic myopathy due to chronic alcoholism. A patient with hypokalemic myopathy occurring in the context of chronic alcoholism was reported. A 56-year-old male patient, heavy drinker for 20 years, complained of marked weakness and acutely developing pains in his limbs. The principal clinical findings were weakness and tenderness of the proximal limbs and girdle muscle. He was unable to lift his head or any extremities from the bed. Deep tendon reflexes were diminished, but not absent. There was no sensory disturbance except for muscle tenderness. These clinical manifestations disappeared gradually by abstinence from drinking, and potassium administration therapy, and the patient recovered completely on the 26th day after onset. On the day after admission (8th day), serum potassium value was 2.2 mEq/L, and serum CPK activity was 4270 IU. The ECG pattern was consistent with a diagnosis of low potassium content in serum, and the EMG pattern was consistent with a diagnosis of myopathy. These electrophysiological findings had a tendency to recover from this pattern to normal range correspondingly with clinical improvement. The repeated muscle biopsies showed that vacuolation, hyaline degeneration and significant phagocyte infiltration were observed in the muscle on the 9th day after the onset of muscle weakness, and that these pathological findings disappeared almost completely three weeks later. The frequently repeated examinations of potassium content and CPK activity in sera showed that there was a close correlation between these biochemical abnormalities and clinical improvement. The pathogenesis of alcoholic myopathy and significance of CPK abnormality in chronic alcoholism were discussed. ( info) |
| We report a 76-year-old woman who developed TdP ventricular tachycardia induced by combined use of clarithromycin and disopyramide. She had a history of myocardial infarction 5 years earlier and has taken disopyramide for supraventricular arrhythmias. In addition, she had taken clarithromycin for upper respiratory tract infection. On admission, an ECG showed prolongation of QTc interval to 0.71 seconds and self-terminating TdP occurred several times. disopyramide was metabolized by the cytochrome enzyme CYP3A4 and clarithromycin competitively inhibits this enzyme, probably resulting in an increase in plasma concentration of disopyramide. We should consider this possibility when prescribing clarithromycin in combination with antiarrhythmic agent disopyramide. ( info) |
| A 61-year-old woman developed hypokalemia, atrioventricular block and ventricular tachycardia with syncope after habitual drinking 2 to 3 liters of oolong tea per day. She had been suffering from rheumatoid arthritis and sjogren's syndrome and her serum albumin was decreased (2.9 g/dl). Oolong tea contains caffeine at approximately 20 mg/dl. Great quantities of caffeine can induce hypokalemia. The serum protein binding caffeine is albumin. Accordingly, in patients with hypoalbuminemia, caffeine is apt to induce hypokalemia. This case suggested that great quantities of oolong tea, one of the so-called "healthy" drinks, result in serious symptoms for patients with hypoalbuminemia. ( info) |
8/707. Licorice-induced hypokalemic myopathy and hypokalemic renal tubular damage in anorexia nervosa. A patient with a history of anorexia nervosa developed licorice-induced hypokalemic myopathy. With potassium replacement, high CPK blood level and myopathic signs returned to normal. However, the patient manifested persistent hypokalemia and impaired renal function to concentrate and acidify the urine. Renal biopsy demonstrated intense degeneration and vacuolation of tubules with a normal glomerus which was consistent with hypokalemic nephropathy. Prolonged hypokalemia in anorexia nervosa is sometimes attributed to surreptitious purging or taking diuretics, but it is necessary to check the urine pH, the urine-specific gravity, and the urine potassium level in order to find underlying renal damage even after hypokalemic myopathy is treated successfully. ( info) |
| We describe the case of a 56-year-old man with severe muscle weakness due to heavy hypokalemia (serum potassium 1.44 mmol/l) associated with inappropriate kaliuria and alkalemia. Subsequent investigation revealed the presence of ectopic ACTH hypersecretion due to a small-cell lung carcinoma. A significant clinical/laboratory improvement was achieved following chemotherapy-induced regression of the primary tumor. The profound hypokalemia was probably the result of cortisol hypersecretion, which in concert with the ACTH-induced decreased 11beta-hydroxysteroid dehydrogenase activity can exhibit an increased mineralocorticoid activity. In addition, other ACTH-dependent mineralocorticoids may play a contributory role in the development of severe hypokalemia. ( info) |
10/707. Hypokalaemic paralysis revealing Sjogren syndrome in an elderly man. A 73 year old white man presented with life threatening hypokalaemic paralysis requiring admission to an intensive care unit. Biochemical investigations showed severe hypokalaemia with hyperchloraemic metabolic acidosis, a spot urine pH of 6.5, and a positive urinary anion gap, establishing the diagnosis of distal renal tubular acidosis. Autoimmune tests revealed Sjogren syndrome as the underlying cause of the distal renal tubular acidosis. Full recovery followed potassium and alkali replacement. This dramatic presentation of Sjogren syndrome has not previously been reported in an elderly man. ( info) |