LONG QT SYNDROME IN HAEMODIALYSIS PATIENT: A CASE REPORT

Transcription

1 Shih-Ta Shang et al. LONG QT SYNDROME IN HAEMODIALYSIS PATIENT: A CASE REPORT Shih-Ta Shang, Bing-Yi Liu Abstract The long QT syndrome (LQTS) is caused by congenital and acquired factors. The most common acquired cause of a prolonged QTc interval is the use of drugs, followed by electrolyte imbalance. A 50-year-old male who is a case of end-stage renal disease. The status of 10-days diarrhea suffered the patient before admission. Sudden cardiac arrest developed during the first-hour haemodialysis (HD). The LQTS in polymorphic ventricular tachycardia (torsades de pointes) was observed in the intensive-care unit. This possibility should be a consideration in a patient presenting with electrolyte imbalance, in which HD increased the QTc interval as a predictor of severe arrhythmias or sudden cardiac death. Key words: Long QT syndrome, Haemodialysis, QTc interval, Hypokalemia Introduction There are higher percentages of end-stage renal disease (ESRD) patients with dialysis therapy that have prolonged QT interval corrected for heart rate (QTc) and hence are susceptible to ventricular arrhythmias, torsades de pointes (TdP). Haemodialysis (HD) patients are at an increased risk of sudden death. Patients with chronic renal failure had a greater QTc interval and QTc dispersion compared with the control subjects. 1 Floccari and his colleagues showed that an increased in QTc dispersion during the first hour of HD, when arrhythmias frequently occur, was inversely correlated with the rapid removal of serum potassium. 2 We describe a case of ESRD patient who developed long QT syndrome (LQTS) in polymorphic ventricular tachycardia, TdP. We also review the literatures for further comment. Case Report A 50-year-old male with the history of noninsulin dependant diabetes mellitus for 8 years and the history of ESRD in regular HD for 5 years. He underwent subtotal gastrectomy due to gastric ulcer about 20 years ago. Two weeks before admission, he sustained watery diarrhea 3 to 5 times a day, in which the above symptom lasting for more than 10 days. He ever came to our emergent department for therapy. On the day of admission, he came to our hospital for regular HD. He was afebrile with normal vital signs on the beginning of HD. The states of conscious loss, transient cardiac arrest and respiratory failure Correspondence: Dr. Bing-Yi Liu Department of Internal Medicine, Armed Forces Tao-Yuan General Hospital; No. 168, Chueng- Hsieng Rd. Lueng-Tan, Tao-Yuan 325, Taiwan Phone: ; Fax:

2 Long QT syndrome of the patient developed during first hour HD. The emergent cardiac-pulmonary resuscitation and endotracheal intubation were done. His blood pressure returned to 157/93 mmhg, and his heart rate was 115 beats per minutes. Later, he was sent into intensive-care unit (ICU) for further treatment. There were no pitting edematous change of both lower extremities, but grade 2 of 6 pansystolic murmur on apex. The white cell count was 8840/ L, hemoglobin level was 8.0g/dL and the hematocrit was 23.4%. The chemical values of blood including that the sodium level was 136mmol/L, the potassium level was 2.5mmol/ L, the calcium level was 8.4mg/dl, the magnesium level was 1.92mg/dL, the BUN was 16mg/ dl and the creatinine was 4.9 mg/dl. The remaining laboratory data were all within normal limits, including cardiac enzymes. The transient ventricular tachycardia (Fig. 1) and TdP (Fig. 2) were frequently attacking in the initial two hospital days. The echocardiography demonstrated the evidence of left ventricular hypertrophy, moderate mitral regurgitation and tricuspid regurgitation. The measured right ventricular systolic pressure was 55mmHg and the left ventricular ejective fraction was 50%.The patient recovered well after keeping the electrolytes balance, and no further episodes of TdP. Fig. 1. Transient ventricular tachycardia from event recorder. Fig. 2. Polymorphic ventricular tachycardia (torsades de pointes) from event recorder. 243

3 Shih-Ta Shang et al. Discussion The LQTS is caused by congenital and acquired factors, which is now recognized more commonly in clinical practice. Tranditionally, the upper limits of the QTc interval are below 460 msec for women and below 440 msec for men. 3 The prolonged QTc interval is a definite increase in risk of cardiac events (palpitations, syncope, cardiac arrest, or sudden death). 4 Bazett correction formula (QTc=QT RR 1/2 ) is still the most widely used method for measuring QTc, although it has been criticized for being in accurate at fast heart rates (>90 beats/min). 5 There are two hereditary variants of congenital LQTS. One is associated with deafness, 6 and one is not; 7,8 they are referred to as the autosomal recessive inheritance (Jervell and Lange-Nielsen syndrome) and as the autosomal dominant inheritance (Romano-Ward syndrome). Both of these syndromes usually manifest in childhood or adolescence, which is an ion channel disease related to the malfunctions in the transmembrane sodium or potassium ion channel proteins. 6-9 In comparison, the most common acquired cause of a prolonged QTc interval is the use of drugs (Table 1), followed by electrolyte imbalance (hypokalemia, hypomagnesmia, hypo- Table 1. Main Cause or Risk Factors of the Acquired Long QT Syndrome (LQTS) 1. Drugs* with risk of TdP** Amiodarone, arsenic trioxide, astemizole, bepridil, chloroquine, chlorpromazine, cisapride, clarithromycin, disopyramide, dofetilide, domperidone, droperidol, erythromycin, halofantrine, haloperidol, ibutilide, levomethadyl, mesoridazine, methadone, pentamidine, pimozide, probucol, procainamide, quinidine, sotalol, sparfloxacin, terfenadine, thioridazine with possible risk of TdP Alfuzosin, amantadine, atazanavir, azithromycin, chloral hydrate, clozapine, dolasetron, felbamate, flecainide, foscarnet, fosphenytoin, gatifloxacin, gemifloxacin, granisetron, indapamide, isradipine, levofloxacin, lithium, moexipril/hctz, moxifloxacin, nicardipine, octreotide, ofloxacin, ondansetron, paliperidone, perflutren lipid microspheres, quetiapine, ranolazine, risperidone, roxithromycin, sunitinib, tacrolimus, tamoxifen, telithromycin, tizanidine, vardenafil, venlafaxine, voriconazole, ziprasidone with conditional risk of TdP Amitriptyline, amoxapine, ciprofloxacin, citalopram, clomipramine, desipramine, doxepin, fluconazole, fluoxetine, galantamine, imipramine, itraconazole, ketoconazole, mexiletine, nortriptyline, paroxetine, protriptyline, sertraline, solifenacin, trimethoprim-sulfamethoxazole, trimipramine 2. Electrolyte imbalance Hypokalemia, hypomagnesemia, hypocalcemia 3. Toxins Cocaine, organophosphorus compounds 4. Severe bradycardia Sick sinus syndrome, high-grade atrioventricular block, hypothyroidism, hypothermia 5. Other causes or risk factors Existing long QT interval, history of acquired LQTS or TdP, female gender, recent conversion from atrial fibrillation, rapid intravenous infusion rate, increased adrenergic tone immediately before TdP, subarachnoid hemorrhage, stroke, myocardial ischemia, congestive heart failure, left ventricular hypertrophy, protein-sparing fasting, autonomic neuropathy, human immunodeficiency virus disease * A full list of drugs that have been reported to prolong the QT interval is available at ** TdP, Torsades de Pointes 244

4 Long QT syndrome calcemia). Other risk or precipitation factors causing acquired LQTS include toxins (cocaine, organophosphorus compound), cardiac events (severe bradycardia, myocardial ischemia, congestive heart failure, existing long QT interval, recent conversion from atrial fibrillation), female gender, increased adrenergic tone, subarachnoid hemorrhage, stroke, protein-sparing fasting by using liquid protein diets, autonomic neuropathy, and human immunodeficiency virus disease. 10,11 Given the characteristic features of LQTS, the typical cases present no diagnostic difficulty for the physicians aware of the disease. However, borderline cases are more complex and require the evaluation of multiple variables besides clinical history and surface electrocardiogram. To overcome these difficulties, Schwartz et al. have described a set of criteria to assist in diagnosing the LQTS which based on the various electrocardiographic (ECG) findings, the clinical features and the familial history. 3 Therefore, further screening ECGs from other familial members would be necessary. Although molecular genetic testing is useful in borderline cases, it remains primarily a research tool and is no available for routine screening. 10 Even exercise testing is not useful for diagnosis, it may be performed in borderline cases because of possible abnormal lengthening of the QTc interval during the recovery phase in patients with the LQTS. 12 The incidence of cardiovascular events in ESRD patients is 10 times comparing with controls. The mortality due to cardiovascular events is more than half of ESRD patients. 13 The overall mortality rate in untreated LQTS patients can be as high as 70% in 10 years. 14 Due to the high mortality rates, treatment is necessary in symptomatic LQTS patients. Patient with LQTS should keep away from any QT-prolonging drug or condition. The choice of treatment for LQTS was summarized in Table 2. 10,11 In short-term treatment, intravenous magnesium and temporary transvenous cardiac pacing are useful for congenital and acquired cases of the syndrome, but use of intravenous isoproterenol is not effective in the congenital forms. Table 2. Treatment for Long QT Syndrome (LQTS) 10,11 1. Short-term treatment Magnesium sulfate Isoproterenol* Lidocaine Potassium chloride Temporary transvenous cardiac pacing 2. Long-term treatment Beta-blockers Permanent pacemaker Implantable cardioverter defibrillator Left thoracic sympathectomy Mutation-based therapy Correction of electrolyte imbalance 3. Treatment of asymptomatic patients Beta-blockers * Avoid using in patients with congenital LQTS or in those with ischemic heart disease because of its sympathomimetic effect. Propranolol has been widely used, but all beta-blockers should be effective Such as sodium channel blockers, flecainide and mexiletine Including hypokalemia, hypomagnesemia and hypocalemia Long-term treatment has its purpose to shorten the QTc interval and to prevent recurrences of TdP. Therapy with beta-blockers is the mainstay of long-term treatment. A permanent pacemaker should be implanted in patients who are symptomatic despite full doses of beta-blockers and in those in whom bradycardia is a prominent feature of the syndrome. The implantable cardioverter-defibrillator prevent sudden cardiac death when TdP is prolonged or degenerates to ventricular fibrillation, and the use of a betablocker should therefore be continued to prevent the precipitation of TdP. Left thoracic sympathectomy should be used as a second-line therapy. Recent advances in understanding the genetics of the congenital LQTS have suggested the possibility of mutation-specific therapy, although their use as a first-line treatment awaits further investigation. Priori et al. also suggested the prophylactic therapy for asymptomatic patients with intermediate to high risk of cardiac events,

5 Shih-Ta Shang et al. in which investigators have recommended treating asymptomatic patients with beta-blockers. First episodes of TdP can be fatal, the appropriated therapy markedly improve survival and reduce the mortality to <5%. 3,11 Our patient subsided from diarrhea before haemodialysis. We still missed the state of unrecovered hypokalemia in which LQTS should be considered as a possible underlying disorder. Acquired LQTS is a recognized cardiovascular problem that can precipitate TdP, a potentially fatal arrhythmia. It was also unfortunate that the haemodialysis made the worsen state of hypokalemia and the other possible electrolytes imbalance, which leading the fetus tachyarrhythmia of TdP. The QTc interval does increase during the haemodialysis, in which leading the episodic TdP. The dialysis-induced increased of the QTc interval should be a consideration as predictor of severe arrhythmias or sudden cardiac death. References 01. Yildiz A, Akkaya V, Sahin S, et al. QT dispersion and signal-averaged electrocardiogram in hemodialysis and CAPD patients. Perit Dial Int 2001;21: Floccari F, Aloisi E, Nostro L, et al. QTc interval and QTc dispersion during haemodiafiltration. Nephrology 2004;9: Schwartz PJ, Moss AJ, Vincent GM, Crampton RS. Diagnostic criteria for the long QT syndrome. An update. Circulation 1993;88: Roden DM. Clinical practice. Long-QT syndrome. N Engl J Med 2008;358: Bazette HC. An analysis of the time-relations of electrocardiograms. Heart 1920;7: Jervell A, Lange-Nielsen F. Congenital deaf-mutism, functional heart disease with prolongation of the Q- T interval and sudden death. Am Heart J 1957;54: Romano C, Gemme G. Rare cardiac arrhythmias of the pediatric age II syncopal attacks due to paroxysmal ventricular fibrillation. Clin Pediatr 1963;45: Ward OC. A new familial cardiac syndrome in children. J Ir Med Assoc 1964;54: Towbin JA, Vatta M. Molecular biology and the prolonged QT syndromes. Am J Med 2001;110: Chiang CE. Congenital and acquired long QT syndrome. Current concepts and management. Cardiol Rev 2004; 12: Khan IA. Clinical and therapeutic aspects of congenital and acquired long QT syndrome. Am J Med 2002;112: Swan H, Toivonen L, Viitasalo M. Rate adaptation of QT intervals during and after exercise in children with congenital long QT syndrome. Eur Heart J 1998; 19: Beaubien ER, Pylypchuk GB, Akhtar J, Biem HJ. Value of corrected QT interval dispersion in identifying patients initiating dialysis at increased risk of total and cardiovascular mortality. Am J Kidney Dis 2002;39: Moss AJ, Schwartz PJ, Crampton RS, Locati E, Carleen E. The long QT syndrome: a prospective international study. Circulation 1985;71: Priori SG, Schwartz PJ, Napolitano C, Bloise R, Ronchetti E, Grillo M et al. Risk stratification in the long-qt syndrome. N Engl J Med 2003;348:

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