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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,The Long QT Syndrome,Overview and Management,Edited by A.Kharazi M.D,Cardiac electrophysiologist,The Long QT SyndromeOverview a,LQTS Outline,?,Background,?,Identification,?,Therapies Available,?,Current Management,?,Ongoing Research,?,Case Studies,?,Conclusions,LQTS Outline?Background ?Ident,Long QT Syndrome,Background and the Risk of,Sudden Cardiac Death,Long QT SyndromeBackground and,Sudden Cardiac Death (SCD),?,Affects 350,000 -,400,000 each year in,the US alone,?,Only 5% of victims survive,?,Causes of SCD may include structural heart,disease or a genetic channelopathy,?,Recognition of risk factors can help identify,those at risk of SCD,Sudden Cardiac Death (SCD)?Aff,Risk Factors for SCD in,Young People,?,Structural congenital heart disease -,before,and after corrective surgery,?,Congenital anomalies of coronaries,?,Myocarditis,?,Hypertrophic and other cardiomyopathies,?,Wolff-Parkinson-White Syndrome,?,Long QT Syndrome,Risk Factors for SCD in Young,LQTS: Historical Aspects,1957:,1st LQTS family reported,1963-1964:,Romano-Ward Syndrome,1958-1970:,25 LQTS cases reported,1971:,1st LQTS Rx (left stellate,ganglionectomy),1979:,LQTS Registry Started,1991-2001:,6 LQTS genes identified,LQTS: Historical Aspects1957:,Long QT Syndrome,?,Genetic disorder (1:5,000-10,000),?,ECG evidence: QTc interval prolonged,?,440 ms in males,?,450 ms in females,?,Hallmark arrhythmia: Torsade de pointes VT,?,Primary presenting symptom: Syncope,?,SCD in children or young adults,Long QT Syndrome?Genetic disor,LQTS: Identification,LQTS: Identification,LQTS: Identification of Risk,?,Most common presenting symptom:,unexplained syncope.,?,Syncope on exertion in pediatric patients,should be considered malignant until proven,otherwise.,?,History & ECG:,Onset and offset of syncopal episode,Siblings, or family members with unexplained syncope or,sudden death,Family history of “seizures” or congenital deafness,Prolonged QTc on ECG,LQTS: Identification of Risk?M,Syncope,Slow Onset,Abrupt Onset,Abrupt Onset,Slow Offset,Abrupt Offset,Slow Offset,Seizure disorder,Hyperventilation,Hypoglycemia,Obstructive,Arrhythmic,Vascular,Aortic Stenosis,HCM, Myxoma,Brady,Tachy,Vasovagal,Orthostatic,Hypertension,SyncopeSlow OnsetAbrupt OnsetA,Causes of Arrhythmic Syncope,?,Very rapid VT or TdP, with hypotension,?,Atrial fibrillation or atrial flutter with very,rapid ventricular response as in WPW,?,AV block,?,Sinus arrest,Causes of Arrhythmic Syncope?V,Holter ECG Recording in LQTS Patient with Syncope,(,representative strips of ECG recording, part 1 of 2),Holter ECG Recording in LQTS P,Holter ECG Recording in LQTS Patient with Syncope,(representative strips of ECG recording, part 2 of 2),Holter ECG Recording in LQTS P,LQTS: Clinical Features,Symptoms,?,Syncope,?,Seizures,?,Sudden death,?,Palpitations or,“chest pain”,ECG Signs,?,Prolonged QTc,?,Torsade de pointes,LQTS: Clinical FeaturesSympto,LQTS ECG Patterns,Circ 1992;85Suppl I:I140-I144,LQTS ECG PatternsCirc 1992;85,Circ 1992;85Suppl I:I140-I144,Additional LQTS ECG Patterns,Circ 1992;85Suppl I:I140-I14,What Should You do,with the ECG?,?,Dont rely on computer evaluation of ECG,?,Obtain an independent review of the ECG,?,Have an experienced cardiologist measure,the QTc interval,?,If the ECG is suspicious for LQTS, refer the,patient for cardiac evaluation,What Should You do with the EC,Circ 1993;88:782-784,LQTS: Diagnostic Criteria,?,ECG findings:,?,QTc, TdP, notched,T waves, slow heart rate for age,?,Clinical history: syncope, seizures, aborted,cardiac arrest,?,Family history: family member with LQTS,unexplained SCD in a first-degree relative,who was 55yrs of age,Circ 1993;88:782-784LQTS: Dia,AJC 1993;72:21B,QTc Interval and Risk,1.0,1.6,2.2,2.8,440,520,600,680,QTc,R,i,s,k,f,o,r,C,a,r,d,i,a,c,E,v,e,n,t,AJC 1993;72:21BQTc Interval an,LQTS: Who is at Risk for SCD?,?,Aborted cardiac arrest,?,Family history of unexplained,sudden death,?,Syncope,?,Torsade de pointes,?,T-wave alternans,?,Prolonged QTc,LQTS: Who is at Risk for SCD?,Circ 1991;84:1136-1144,Probands,Affected,Undetermined,Unaffected,Probability of Cardiac Event in LQTS,Circ 1991;84:1136-1144Probands,Circ 2001;103:89-95,Mayo Clin Proc. 1999;74:1088-1094,Triggering Events for,Syncope or SCD,?,3 main factors contributing to syncope,or SCD,Exercise (LQT1), especially swimming,Emotions or emotional stress (LQT2),Events occurring during sleep or at rest,with or without arousal (LQT2 or LQT3),Circ 2001;103:89-95Mayo Clin P,Circ 2001;103:89-95,62,26,3,13,43,29,13,19,39,0,10,20,30,40,50,60,70,LQT1,LQT2,LQT3,Exercise,Emotional Stress,Rest,P,e,r,c,e,n,t,Occurrence of,Gene-Specific Triggers,Circ 2001;103:89-9562263134329,JCE 1999;10:1664-1683,Basis for the Long QT Syndrome,JCE 1999;10:1664-1683Basis for,LQTS: Phenotype-Genotype,Considerations,?,6 genotypes; 200 different mutations,?,Clinical differences among LQT1, LQT2,& LQT3 genotypes,?,Clinical variability within a genotype,?,Clinical variability among members of,a family with the same gene mutation,suggests presence of modifier genes,LQTS: Phenotype-Genotype Cons,Moss AJ, et al. Circulation 1995;92:2929-2934,T-wave Morphology in LQTS,by Genotype,Moss AJ, et al. Circulation 19,NEJM 1998;339:960-965,Probability of a Cardiac Event,No. of Subjects,LQT1 group,112,72,36,27,19,LQT2 group,72,56,29,16,11,LQT3 group,62,56,36,24,16,NEJM 1998;339:960-965Probabili,Therapies Available and,Current Management,Therapies Available and Curren,Drugs in Long QT,?,Certain drugs may provoke life-threatening,arrhythmias in LQTS patients,Examples:,?,Antiarrhythmic: procainamide, quinidine, amiodarone, sotalol, et al,?,Antihistamine: astemizole, terfenadine, et al,?,Antimicrobial/antifungal: thiomethoprim sulfa, erythromycin,ketoconazole, et al,?,Psychotropics: haloperidol, risperidone, thioridazine, tricyclics, et al,?,Other: epinephrine, diuretics, cisapride, bepridil, ketanserin, et al,?,Avoid nonessential OTC medications,?,For more information see:,www.qtdrugs.org,Drugs in Long QT?Certain drugs,Current Treatments,?,Left stellate ganglionectomy (occasionally,utilized in infants and patients refractory,to other forms of therapy),?,Beta blockers,?,Pacemakers,?,Implantable Cardioverter Defibrillators (ICDs),Current Treatments?Left stella,Management by Genotype,?,LQT1 and LQT2 benefit the most from,?,-blocker therapy,?,The benefit of ?,-blocker therapy is less,clear in LQT3.,?,ICDs indicated:,if the patient presents as SCD survivor or,aborted cardiac arrest,if ?,-blockers are not effective in preventing,cardiac events,Management by Genotype?LQT1 an,Probands,AFM,?,(n=581),(n=288),Risk exposure, yrs,5.2,4.5,(pre-,and post-,?,B),Pre-,?,B Post-,?,B Pre-,?,B Post,?,B,Pts with events 462,194*,92,49*,Number events,1671,623*,245,138*,Events/pt,3.0,1.1*,0.9,0.5*,Events/pt/year,1.0,0.3*,0.3,0.15*,LQTS: Cardiac Events Before and,After,?,-blockers,Circ 2000;101:616-623,?,Affected Family Member * P0.01 vs. pre-,?,-blocker,ProbandsAFM?(n=581)(n=288)Risk,Circ 2000;101:616-623,Efficacy of,?,-blockers in LQTS,?,Significant reduction in frequency of,syncopal events,?,Cardiac events continued to occur,?,May reduce the rate of SCD,?,Reductions in rate of cardiac events,0.97,1.42 to 0.31,0.86 events/year in probands,0.26,0.84 to 0.15 ,0.69 events/year in affected,family members,?,P500ms),?,Beta-blocker therapy initiated,?,No further cardiac events noted over 5 years,?,Can you consider withdrawing beta-blocker,therapy?,?,Is an ICD indicated?,Case Study 1?13 year old male,Case Study 2,?,Young male athlete diagnosed with LQTS,?,Beta-blockers prescribed,?,Patient stops drugs because he feels better,without them,?,What should the physician do?,Case Study 2?Young male athlet,Case Study 3,?,15 year old male,?,ECG as part of routine physical,?,QTc = 450ms,?,Asymptomatic,?,No family history,?,Question: Is this LQTS?,Case Study 3?15 year old male?,Conclusions,?,Unexplained syncope with exertion in children,and young adults should be considered,serious until proven otherwise.,?,ECGs should be obtained on the patient and,read by a cardiologist or pediatric cardiologist,if patient is a child.,?,ECGs should be obtained on all immediate,family members.,?,Referral to a cardiac specialist if suspicious,for LQTS.,Conclusions?Unexplained syncop,Long QT Resources,?,Cardiac Arrhythmias Research and Education,(CARE) Foundation:,www.longqt.org,?,Cardiac Arrest Survivors Network (CASN):,www.casn-network.org,?,International Registry for Drug-Induced,Arrhythmias, including drugs to use with,caution or avoid in Long QT patients:,www.qtdrugs.org,Long QT Resources?Cardiac Arrh,
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