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Biomedical subjects

M Sisáková

Publications and source records attributed to M Sisáková.

6 recordsLinked to original sources
PubMed2006

[Mutational analysis of LQT genes in individuals with drug induced QT interval prolongation].

BACKGROUND: In a long list of non-cardiovascular drugs a risk of QT interval prolongation and thus an increased risk of malignant arrhythmias has been described. The precise mechanism remains unclear. Many of these drugs are potent blockers of cardiac ion channels. Thus, prolongation of repolarization could be caused by latent ion channel genes mutations which are revealed under stress conditions. GROUP OF PATIENTS AND METHODS: Patients were recruited in screening of antipsychotic drugs with proarrhythmic potential, another sporadic cases were reffered from regional hospitals. In 13 individuals pathologic values of corrected QT interval (> 0.44 s in males, > 0.46 s in females) were observed. Eleven patients gave their consent to mutational analysis of KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2 and KCNJ2 genes (associated with congenital long QT syndrome). RESULTS: At present complete results of mutational analysis are available in 8 patients. In 5 individuals changes in DNA sequence were found which are considered normal variants according to the literature (nucleotide and aminoacid polymorphisms, intronic variants). In 1 male a KCNQ1 gene mutation A590T was identified (yet not reported in literature). CONCLUSION: Mechanisms of drug-induced QT interval prolongation is complex and it cannot be explained simply by ion channel disorders.

DNA Mutational Analysis↗
PubMed2006

[Extension of QT interval as a consequence of risk factor accumulation--case study].

BACKGROUND: Many non-cardiovascular drugs have a potential for QT interval prolongation. This phenomenon can be related to occurence of ventricular tachycardia torsades de pointes, syncopi and even sudden death. DESCRIPTION OF THE CASE: A female patient treated with antracycline cytostatics developed a depression of left ventricle ejection fraction. At the same time she was administered 2 common drugs with proarrhythmic potential--terfenadine and itraconazole. In this patient hypokalemia also occured. Combination of the above mentioned risk factors led to QT interval prolongation and frequent ventricular tachycardias torsades de pointes degenerating in ventricular fibrillations with need of repeated defibrillations. Both drugs were withdrawn and dysiontaemia corrected. Then arrhythmias disappeared and QT interval completely normalized. In this patient the congenital long QT syndrome was not proved. DISCUSSION AND CONCLUSIONS: In proarrhythmic effect of non-cardiovascular drugs the following factors play role: predisposition of a particular individual, "repolarization reserve", interindividual differences in drug metabolism. The risk factors are age, sex, dysiontaemia, heart disease and drug interactions. By different choice of medication and attention to risk factors teh life threat to the described patient could have been avoided.

Adult↗
PubMed2003

[Comparison of various methods of correction of QT intervals during exercise in familial long QT interval syndrome].

BACKGROUND: Pathologic prolongation of QT interval is related to increased risk of arrhythmias. Changes of this parameter are influenced by many conditions, the most important is heart rate. Several formulas have been proposed for mathematical description of QT interval/heart rate relationship. The aim of this study was comparison of different QT interval correction formulas in families with congenital long QT syndrome (LQTS). METHODS: In 28 members of 6 families with LQTS occurrence bicycle ergometry testings were performed. QT and RR intervals were measured before exercise, at peak exercise and in the 1st and the 6th minute of restitution. For QT interval correction single-parameter formulas by Bazett, Fridericia, Malik and Framingham study were used. In 3 families the results could be correlated with genetically proved diagnosis (KCNQ1 gene mutations in 2 families, HERG-KCNH2 gene mutation in the other). RESULTS: In the described group the genetically established diagnosis of LQTS correlated at best with values obtained with correction by Bazett. All the mutation carriers were correctly identified only by this method. The Fridericia, Malik and Framingham formulas failed to identify 2 patients--mutation carriers (both KCNQ1 and HERG-KCNH2 mutations). DISCUSSION: Because of simplicity the Bazett formula remains the most common method of QT interval correction. Moreover, in our study this formula appeared to be the most sensitive for clinical diagnosis of LQTS.

Algorithms↗
PubMed1997

[Significance of vegetative nerve tone in patients with vasovagal neurocardiogenic syncope].

The timely provided and precise diagnostic of the syncopal states as well as their causal therapy is a main subject of many medical branches interest within last time. Our work was concentrated on a vasovagal neurocardiogenic syncope. The definition of the vegetative nervous tonus participation on its development by a method of evaluation of the heart rate variability as well as the review of a possibility to the application of quantification these results to a prediction of vasovagal reaction, respective of its malignant variant, was the main aim of our effort. Our results enable a conclusion, that the observation of aquiet autonomic nervous tonus does not represent a contribution to a differential diagnostics of syncope of uncleared etiology with a suspicion on vasovagalous neurocardiogenous syncope, because the basal vagal tonus does not allow the forecast of head upright tilt table testing results as well as determination of the type of respectively provocated vasovagal neurocardiogenic syncope. However, a correlation between an actual reactive vageous tonus surveyed by the SD index for patients with vasovagal neurocardiogenic syncope of the type I and IIa in comparison with healthy persons, was found out. It allows to draw a conclusion, that the vasovagal neurocardiogenic syncope is not homogeneous nosological unit, what results in efforts to it's more detailed classification.

Adult↗
PubMed1995

[Neural syncope--a current therapeutic problem].

Syncope, a state performed by transient loss of consciousness connected with postural tone decrease present still an important therapeutical problem. It can vary from a benign physiological body reaction to a life-limiting situation. The authors of the article present HUT-testing to be a simple, useful and safe method for discovering vasovagal mechanism of the syncope. They notice the experiences with treatment according to the HUT results. The most frequent types of therapy are the pharmacological and the pacing ones, when the former is appropriate for I and III class of VVS the latter then for the II. class. There are some big studies in progress now which should bring more information about this clinical problem.

Humans↗