Clinical presentation, occurrence of sudden infant death, and results of the available therapies in the largest group of patients with short QT syndrome (SQTS), studied so far, are reported.
Clinical ...history, physical examination, electrocardiogram (ECG), exercise stress testing, electrophysiological study, morphological evaluation, genetic analysis and therapy results in 29 patients with SQTS and personal and/or familial history of cardiac arrest are reported. The median age at diagnosis was 30 years (range 4-80). In all subjects, structural heart disease was excluded. Eighteen patients were symptomatic (62%): 10 had cardiac arrest (34%) and in 8 (28%) this was the first clinical presentation. Cardiac arrest had occurred in the first months of life in two patients. Seven patients had syncope (24%); 9 (31%) had palpitations with atrial fibrillation documented even in young subjects. At ECG, patients exhibited a QT interval < or = 320 ms and QTc < or = 340 ms. Fourteen patients received an implantable cardioverter-defibrillator (ICD) and 10 hydroquinidine prophylaxis. At a median follow-up of 23 months (range 9-49), one patient received an appropriate shock from the ICD; no patient on hydroquinidine had sudden death or syncope.
SQTS carries a high risk of sudden death and may be a cause of death in early infancy. ICD is the first choice therapy; hydroquinidine may be proposed in children and in the patients who refuse the implant.
A prolonged QT interval is associated with a risk for life-threatening events. However, little is known about prognostic implications of the reverse-a short QT interval. Several members of 2 ...different families were referred for syncope, palpitations, and resuscitated cardiac arrest in the presence of a positive family history for sudden cardiac death. Autopsy did not reveal any structural heart disease. All patients had a constantly and uniformly short QT interval at ECG.
Six patients from both families were submitted to extensive noninvasive and invasive work-up, including serial resting ECGs, echocardiogram, cardiac MRI, exercise testing, Holter ECG, and signal-averaged ECG. Four of 6 patients underwent electrophysiological evaluation including programmed ventricular stimulation. In all subjects, a structural heart disease was excluded. At baseline ECG, all patients exhibited a QT interval <or=280 ms (QTc <or=300 ms). During electrophysiological study, short atrial and ventricular refractory periods were documented in all and increased ventricular vulnerability to fibrillation in 3 of 4 patients.
The short QT syndrome is characterized by familial sudden death, short refractory periods, and inducible ventricular fibrillation. It is important to recognize this ECG pattern because it is related to a high risk of sudden death in young, otherwise healthy subjects.
Our purpose was to evaluate the efficacy of antiarrhythmic drugs (AADs) in recurrent ventricular fibrillation (VF) associated with inferolateral early repolarization pattern on the electrocardiogram.
...Although an implantable cardioverter-defibrillator is the treatment of choice, additional AADs may be necessary to prevent frequent episodes of VF and reduce implantable cardioverter-defibrillator shock burden or as a lifesaving therapy in electrical storms.
From a multicenter cohort of 122 patients (90 male subjects, age 37 +/- 12 years) with idiopathic VF and early repolarization abnormality in the inferolateral leads, we selected all patients with more than 3 episodes of VF (multiple) including those with electrical storms (> or =3 VF in 24 h). The choice of AAD was decided by individual physicians. Follow-up data were obtained for all patients using monitoring with implantable defibrillator. Successful oral AAD was defined as elimination of all recurrences of VF with a minimal follow-up period of 12 months.
Multiple episodes of VF were observed in 33 (27%) patients. Electrical storms (34 +/- 47 episodes) occurred in 16 and were unresponsive to beta-blockers (11 of 11), lidocaine/mexiletine (9 of 9), and verapamil (3 of 3), while amiodarone was partially effective (3 of 10). In contrast, isoproterenol infusion immediately suppressed electrical storms in 7 of 7 patients. Over a follow-up of 69 +/- 58 months, oral AADs were poorly effective in preventing recurrent VF: beta-blockers (2 of 16), verapamil (0 of 4), mexiletine (0 of 4), amiodarone (1 of 7), and class 1C AADs (2 of 9). Quinidine was successful in 9 of 9 patients, decreasing recurrent VF from 33 +/- 35 episodes to nil for 25 +/- 18 months. In addition, quinidine restored a normal electrocardiogram.
Multiple recurrences of VF occurred in 27% of patients with early repolarization abnormality and may be life threatening. Isoproterenol in acute cases and quinidine in chronic cases are effective AADs.
Short QT syndrome: pharmacological treatment Gaita, Fiorenzo; Giustetto, Carla; Bianchi, Francesca ...
Journal of the American College of Cardiology,
04/2004, Letnik:
43, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The purpose of this study was to evaluate the efficacy of various antiarrhythmic drugs at prolonging the QT interval into the normal range and preventing ventricular arrhythmias in patients with ...short QT syndrome.
Short QT syndrome is a recently described genetic disease characterized by short QT interval, high risk of sudden death, atrial fibrillation, and short refractory periods.
Six patients with short QT syndrome, five of whom had received an implantable cardioverter-defibrillator (ICD) and one child, were tested with different antiarrhythmic drugs, including flecainide, sotalol, ibutilide, and hydroquinidine, to determine whether they could prolong the QT interval into the normal range and thus prevent symptoms and arrhythmia recurrences.
Class IC and III antiarrhythmic drugs did not produce a significant QT interval prolongation. Only hydroquinidine administration caused a QT prolongation, which increased from 263 ± 12 ms to 362 ± 25 ms (calculated QT from 290 ± 13 ms to 405 ± 26 ms). Ventricular programmed stimulation showed prolongation of ventricular effective refractory period to ≥200 ms, and ventricular fibrillation was no longer induced.
The ability of quinidine to prolong the QT interval has the potential to be an effective therapy for short QT patients. This is particularly important because these patients are at risk of sudden death from birth, and ICD implant is not feasible in very young children.
Fluctuations between the diagnostic ECG pattern and non-diagnostic ECGs in patients with Brugada syndrome are known, but systematic studies are lacking. The purpose of this study was to prospectively ...evaluate the spontaneous ECG changes between diagnostic and non-diagnostic ECG patterns in patients diagnosed with Brugada syndrome.
In 43 patients with Brugada syndrome (27 males; mean age 45+/-11 years), 310 resting ECGs were obtained during a median follow-up of 17.7 months. The ECGs were analysed for the presence of coved type, saddle-back type or no, respectively unspecific, changes. A coved-type ECG pattern with more than 2 mm ST-segment elevation in at least two right precordial leads was defined as diagnostic. The patients were compared for different clinical characteristics with respect to the pattern of fluctuations. Out of a total of 310 ECGs, 102 (33%) revealed a coved type, 91 (29%) a saddle-back type, and 117 (38%) a normal ECG. Fifteen patients (35%) initially presented with a diagnostic coved-type ECG. Fourteen patients (33%) with an initially coved-type ECG exhibited intermittently non-diagnostic ECGs during follow-up. Only one patient (2%) presented constantly with a coved-type ECG. Out of 28 patients (65%) with an initially non-diagnostic ECG, eight (19%) patients developed a diagnostic coved-type ECG during follow-up. Twenty patients (47%) revealed a coved-type ECG during ajmaline challenge, but never had a baseline coved-type ECG recorded. No significant differences were found in gender and clinical characteristics among patients with or without fluctuations between diagnostic and non-diagnostic basal ECGs. The rate of inducible ventricular fibrillation was significantly higher in patients with more than 50% coved-type ECGs than in patients with less than 50% diagnostic ECGs.
The prevalence of fluctuations between diagnostic and non-diagnostic ECGs in patients with Brugada syndrome is high and may have an implication on the correct phenotyping and on the risk stratification in patients with Brugada syndrome without aborted sudden cardiac death. For correct phenotyping and risk stratification, repetitive ECG recordings seem to be mandatory.
The short QT syndrome constitutes a new clinical entity that is associated with a high incidence of sudden cardiac death, syncope, and/or atrial fibrillation even in young patients and newborns. ...Patients with this congenital electrical abnormality are characterized by rate-corrected QT intervals<320 ms. Missense mutations in KCNH2 (HERG) linked to a gain-of-function of the rapidly activating delayed-rectifier current I(Kr) have been identified in the first two reported families with familial sudden cardiac death. Recently, two further gain-of-function mutations in the KCNQ1 gene encoding the alpha-subunit of the KvLQT1 (I(Ks)) channel and in the KCNJ2 gene encoding the strong inwardly rectifying channel protein Kir2.1 confirmed a genetically heterogeneous disease. The possible substrate for the development of ventricular tachyarrhythmias may be a significant transmural dispersion of the repolarisation due to a heterogeneous abbreviation of the action potential duration. The implantable cardioverter defibrillator is the therapy of choice in patients with syncope and a positive family history of sudden cardiac death. However, ICD therapy in patients with a short QT syndrome has an increased risk for inappropriate shock therapies due to possible T wave oversensing. The impact of sotalol, ibutilide, flecainide, and quinidine on QT prolongation has been evaluated, but only quinidine effectively suppressed gain-of-function in I(Kr) with prolongation of the QT interval. In patients with a mutation in HERG, it rendered ventricular tachycardias/ventricular fibrillation non-inducible and restored the QT interval/heart rate relationship towards a normal range. It may serve as an adjunct to ICD therapy or as a possible alternative treatment, especially for children and newborns.
We demonstrate how the controlled positioning of a plasmonic nanoparticle modifies the photoluminescence of a single epitaxial GaAs quantum dot. The antenna particle leads to an increase of the ...luminescence intensity by about a factor of 8. Spectrally and temporally resolved photoluminescence measurements prove an increase of the quantum dot’s excitation rate.
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