Long QT Syndrome


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  • Long QT Syndrome (LQTS):Symptoms,Causes,Diagnosis and Treatment

    Long QT syndrome (LQTS) results from structural abnormalities in the potassium channels of the heart, which predispose affected persons to an accelerated heart rhythm (arrhythmia). This can lead to sudden loss of consciousness and may cause sudden cardiac death in teenagers and young adults who are faced with stressors ranging from exercise to loud sounds.

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Long QT Syndrome

  1. 1. ECG of the week<br /><ul><li>Dr. DevendraPatil</li></ul>Prof.Dr. S.Magheshkumar’sUnit<br />
  2. 2. Indira 70/ F Retd. Matron GSH came with chief <br />complains of <br /> Fever since 20-25 days<br /> Intermittent ,high grade asso. with chills n rigors<br /> Taking some oral medication from pvt.<br />K/c/o SHT and DM since 15 yrs on Rx.<br />2 days later she had a cardiac arrest with the following ECG pattern<br />
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  5. 5. ECG findings :-<br />Heart Rate – 50 bpm<br />Regular Sinus rhythm<br />Normal Axis<br /> P wave - normal<br />PR interval - 0.12 sec<br />QRS complex – normal width and shape<br />QT interval – 0.56 sec<br />QTc interval - 0.509 sec<br />T wave – normal<br />Impression :- Bradycardia with acquired prolonged QT syndrome<br />Pt. was shifted to ICCU.<br />
  6. 6. She developed cardiac arrest .<br />Pulse – not felt<br />BP - not recordable<br />ECG showed Vent. Tachycardia <br />200 J Biphasic DC shock was given and was reverted to sinus rhythm <br />
  7. 7. A Temporary Cardiac Pacemaker was inserted following Rt. Femoral Vein Catheterization and she was reverted to sinus rhythm over the next 2 days<br />
  8. 8. QT interval : beginning of Q-wave upto the end of T-wave.<br />QT interval : total duration of ventricular activity.<br />Need for QTc Interval :<br /> The QT interval varies with RR interval. False high values may be noted in Bradycardias.<br />LONG QT SYNDROME<br />
  9. 9. Formula accepted for QTc is:<br />BAZETT’s Formula : QTc = QT ∕√ (RR)<br />A useful rule of thumb is that, with a normal heart rate ( 60 - 100 bpm), the QT interval SHOULD NOT exceed half the RR interval.<br />
  10. 10. LONG QT SYNDROME<br />CONGENITAL<br />ACQUIRED<br />Due to Genetic defects in K+ channels involved during repolarization.<br />Severe form Includes:<br />1. Jervell Lange Syndrome <br />(deafness, syncopal attacks , sudden death )<br />2. Romano Ward Syndrome (similar to Jervell Lange syndrome but without deafness )<br /><ul><li>DRUGS
  11. 11. During Sleep
  12. 12. Hypocalcemia
  13. 13. Acute Myocarditis
  14. 14. Acute Myocadial Infarction
  15. 15. Hypothermia
  16. 16. HOCM
  17. 17. Cerebral Injury
  18. 18. Advanced AV Blocks</li></li></ul><li>Congenital LONG QT SYNDROME<br />LQT1 Gene<br />Most common type<br />QT interval fails to shorten post exercise<br />T wave is broad and occupies majority QT interval<br />Most common triggers: exercise, emotional stress.<br />80% have first presentation &lt; 20 yrs<br />Jervell Lange syndrome and Romano Ward syndrome are severe forms.<br />LQT2 Gene<br />T wave tends to be bifid and notched<br />Additional Triger factors are sleep, auditory stimulation<br />Respond to B-Blockers<br />LQT3 Gene<br />Poorest prognosis amongst all<br />T wave is asymmetrical or Late biphasic<br />Trigger factor : Bradycardia ( sleep )<br />B-Blockers Contraindicated<br />Exercise is not Restricted<br />
  19. 19. DRUGS that may cause QT PROLONGATION<br />AntiarrhythmicsClass 1: ajmaline*, cibenzoline*, dihydroquinidine*, disopyramide, encainide*, flecainide, mexiletine, pirmenol*, procainamide,propafenonequinidine*Class 3:almokalant*, amiodarone, azimilide*, bretylium, dofetilide*, dronedarone*, d-sotalol*, ersentilide*, ibutilide*, nifekalant*, sematilide*, sotalol, terikalant*<br />Anti-anginals/vasodilatorsbepridil*, lidoflazine*, prenylamine*, ranolazine, terodiline*, vardenafil<br />Anti-hypertensivesindapamide, isradipine, moexipril/hydrochlorthiazide, nicardipine<br />Antihistaminesastemizole*, azelastine, diphenhydramine, ebastine*, hydroxyzine, terfenadine*<br />Serotonin agonists and antagonistscisapride*, dolasetron, granisetron, ketanserin*, ondansetron<br />AntimicrobialsMacrolide antibiotics: azithromycin, clarithromycin, erythromycin, roxithromycin*, spiramycin, telithromycin<br />Quinolone antibiotics: ciprofloxacin, gatifloxacin*, gemifloxacin*, grepafloxacin*, levofloxacin, moxifloxacin, ofloxacin, sparfloxacin*<br />Antifungals: cotrimoxazole, fluconazoleOthers: pentamidine, trimethoprimsulfaAntiviral: foscarnet (HIV)<br />
  20. 20. DRUGS that may cause QT PROLONGATION<br />Continued…<br />AntimalarialsChloroquine, halofantrine*, lumefantrine, quinine<br />Psychiatric drugsTricyclic antidepressants: amitriptyline, amoxapine*, clomipramine, desipramine*, doxepin, imipramine, nortriptyline, protriptyline*, trimipramine<br />Phenothiazines: chlorpromazine, fluphenazine, prochlorperazine, thioridazine*, trifluoperazine<br /> Others: atomoxetine, citalopram, clozapine, droperidol*, fluoxetine, haloperidol, levomethadyl*, lithium, maprotiline, mesoridazine, methadone, paroxetine, pericycline, pimozide, quetiapine, risperidone, sertindole, sertraline, trazodone, venlafaxine, zimeldine*, ziprasidone<br />Anticonvulsantfelbamate*, fosphenytoin<br />Anti-migrainenaratriptan, sumatriptan, zolmitriptan<br />Anti-cancerarsenic trioxide, geldanamycin*, sunitib, tacrolimus, tamoxifen<br />Othersalfuzosin,chloral hydrate, clobutinol*, domperidone, galantamine, octreotide, organophosphates*, perflutren lipid microspheres, probucol, solifenacin, tizanidine, tolterodine, vasopressin <br />Stimulant drugsSome cold remedies contain these drugs so it is important always to check the label.adrenaline (epinephrine), amphetamine, cocaine, dexmethylphenidate, dobutamine, dopamine, ephedrine, fenfluramine, isoprenaline (isoproterenol), levalbuterol, metaproterenol, methylphenidate, midodrine, norepinephrine (noradrenaline), phentermine, phenylephrine, phenylpropanolamine, pseudoephidrine, ritodrine, salbutamol (albuterol), salmeterol, sibutramine, terbutaline<br />
  21. 21. Complications OF Long qt syndrome<br />Torsades des pointes ( polymorphic ventricular tachycardia )<br />More commonly seen in women<br /> Manifestation of subclinical LQTS<br /> Potentiated by bradycardia and hypokalemia<br /> drug usually blocks Ikr channel<br /> triggered by early afterdepolarizations due to intracellular Ca+ accumulation from a prolonged actin potential plateau<br />heterogenicity of myocardial repolarisation predisposes to polymorphic ventricular activity<br />
  22. 22. Treatment<br />Caution has to be exercised during administering multiple drug regimes. They may cause QT Prolongation and TDP.<br />Correction of K+ and Mg++ levels<br />Temporary Pacing<br />Cautious Infusion of Isoprotenol<br />Class 1B anti arrythmics(no QT prolongation seen)<br />
  23. 23. THANK YOU<br />