The analysis of QT interval and repolarization morphology of the heart in chronic exposure to lead.

There are no common recommendations regarding electrocardiographic monitoring in occupationally exposed workers. Therefore, the present study was designed to investigate whether exposure to lead results in an increase of selected electrocardiography (ECG) pathologies, such as QT interval prolongation and repolarization disorders, in occupationally exposed workers. The study group included 180 workers occupationally exposed to lead compounds. The exposed group was divided according to the median of the mean blood lead level (PbBmean) calculated based on a series of measurements performed during 5-year observation period (35 µg/dl) into two subgroups: low exposure (LE, PbBmean = 20.0-35.0 µg/dl) and high exposure (HE, PbBmean = 35.1-46.4 µg/dl). The control group consisted of 69 healthy workers without occupational exposure to lead. ECG evaluation included the analysis of heart rate (HR), QT interval and repolarization abnormalities. Mean QT interval was significantly greater in the exposed population than in the control group by 2%. In the HE group, mean QT interval was significantly greater than in the control group by 4% and significantly different from those noted in the LE group. Positive correlations between QT interval and lead exposure indices were also reported. Besides, there was a negative correlation between HR and blood lead level. Increased concentration of lead in the blood above 35 µg/dl is associated with the QT interval prolongation, which may trigger arrhythmias when combined with other abnormalities, such as long QT syndrome. Therefore, electrocardiographic evaluation should be a part of a routine monitoring of occupationally exposed populations.

[Measurement dispersion of the QT interval and its significance in different diseases]. / Pomiar dyspersji odstepu QT i jej znaczenie w róznych schorzeniach.

QT dispersion reflects in homogenecity of ventricular repolarization. It is calculated using 12-leads standard synchronized ECG or 24-hours Holter monitoring. The most common used indicators are: QT dispersion (QTd), based on Bazett's formula corrected for heart rate QT dispersion (QTcd) and QT dispersion ratio (QTdR). QT apex and QTd corrected for total number of leads ECG in which QT interval was counted are rare used. Increased QT dispersion is observed among others: following myocardial infarction (MI), coronary heart disease (CAD), hypertension, chronic heart failure (CHF), long QT syndrome, as well as diabetes. Following mentioned diseases increased QT dispersion has prognostic value for sustained ventricular tachycardia. Dispersion of repolarization > or = 80 ms after MI is a risk factor for sudden cardiac death. Following acute MI decrease of QT dispersion after successful thrombolytic therapy is observed and its value > or = 100 ms is regarded as a marker of reperfusion insufficiency. QT dispersion in patients with CAD correlates with extent of ischemia and decreases after coronary angioplasty (PTCA). In recent years beneficial effect of angiotensin-converting enzyme inhibitors and beta-adrenolytic therapy on QT dispersion was described. Actually the improvement of computerised methods in assessment of QT dispersion is observed, but it require further investigations.

[Tachycardia-induced cardiomyopathy]. / Arytmogenna kardiomiopatia rozstrzeniowa.

Dilated cardiomyopathy induces circulatory insufficiency with poor prognosis. Persistent tachyarrhythmias may be the cause of this disease. At particular high risk for heart damage and insufficiency are young people and children. The group of most dangerous arrhythmias consist of: incessant tachycardia in patients with preexcitation syndrome and supraventricular tachyarrhythmias (atrial flutter and fibrillation, ectopic atrial tachycardia) with high rate of ventricles. The result of arrhythmias is dilatation of the heart and thinness of ventricular walls with hemodynamic disorders. The effective therapy of arrhythmias--ablation of the accessory pathway in patients with pre-excitation syndrome or reversion to sinus rhythm (pharmacological or electric cardioversion) in patients with atrial fibrillation and flutter, often leads to normalisation of heart ejection function and diameter. Therefore it exist important question: is dilated cardiomyopathy the cause or consequence of tachyarrhythmias? Causative antiarrhythmic therapy in these second cases gives a possibility to improve the prognosis in patients with such a disease.

[The effect of bronchofiberoscopy on selected markers of circulatory system function]. / Wplyw bronchofiberoskopii na wybrane wskazniki czynnosci ukladu krazenia.

Bronchofiberoscopy is one of the basic diagnostic tools in pulmonary care. It is therefore of interest to assess the effects of this procedure on circulatory system as well as the risk of possible cardiovascular complications. The study included 56 patients for whom bronchoscopy was a planned diagnostic procedure (9 patients had additionally BAL). Each patient's examination protocol included, among others, ECG by Holter method, the measurement of arterial pressure and 12-lead ECG performed before and after the examination. The patients were divided into two groups: those with ventricular arrhythmia diagnosed by ECG at rest and those without arrhythmia signs in ECG done prior to bronchofiberoscopy. The analysis of data revealed that bronchofiberoscopy was associated with considerable increase of arterial pressure in both groups of patients as well as with increased ventricular arrhythmia, particularly in patients with previous history of arrhythmia. Additional load upon the respiratory system exerted by BAL did not have a significant effect on the circulatory system.

[Dispersion of the QT interval in unstable angina pectoris]. / Dyspersja odstepu QT w niestabilnej chorobie wiencowej.

UNLABELLED: Increased dispersion of the QT interval is a risk factor of sudden cardiac death. In unstable angina pectoris (UA) a few authors described QT dispersion. The aim of the study was to assess QT dispersion in patients with UA in comparison to the healthy subjects and analysis QT dispersion according to the presence during in-hospital stay significant cardiac events like: death due to cardiological causes, myocardial infarction and urgent revascularization. Study group consisted of 54 patients with UA in a class IIIB of Braunwald classification (18 women, 36 men, mean age: 58.2 +/- 9.6 years). In 40 patients after pharmacological treatment stabilization in the first three days of hospitalization was achieved and during in-hospital stay significant cardiac events were not observed--group I. In 14 patients during in-hospital stay significant cardiac events were present, including 5 death due to cardiological causes--group II. During first two days of hospitalization coronary angiography was performed in all patients. The control group comprised 25 healthy subjects (8 women, 17 men, mean age 56.4 +/- 6.1 years). On admission to the hospital in all patients and in control group, using standard 12-leads ECG, following parameters were calculated: QT dispersion (QTd), corrected QT dispersion based on Bazett's formula (QTcd) and QT dispersion ratio (QTdR). In the study group as well as in group I and II values of QTd, QTcd and QTdR were significantly higher than in healthy subjects. In group I all the QT parameters were significantly lower than in group II (QTd: 56.8 +/- 11.2 vs 68.6 +/- 16.6 ms, p = 0.002). The highest value of QT dispersion was found in patients who died during in-hospital stay and it was significantly higher than in survivors (86.0 +/- 13.4 vs 57.1 +/- +/- 10.6 ms, p = 0.004). A cut-off value for QTdR > or = 9% identified patients with high risk of sudden cardiac death. CONCLUSIONS: QT dispersion analysis in unstable angina pectoris allows to distinguish patients according to the risk of sudden cardiac death. Patients with high risk of sudden cardiac death identify the best QTdR.

[The assessment and clinical significance of heart rate variability]. / Metody oceny i znaczenie kliniczne zmiennosci rytmu zatokowego.

Heart rate variability (HRV) is a phenomenon to generation through the sinus node consecutive impulses in the different succession. HRV is regarded as a marker of autonomic nervous system tone of the heart. To assess HRV following methods: time domain, frequency domain and non-linear analysis are known. Time domain parameters correlate with frequency domain parameters. Some parameters can be used substitution, particularly reflect parasympathetic activity: rMSSD, pNN50 and HF. In clinical practice the most useful is time domain analysis based on 24-hours ecg Holter monitoring. Among time domain parameters the most significant prognostic value has SDNN. Decreased HRV following many diseases has been described. Significant prognostic value of decreased HRV after myocardial infarction (MI) and in patients with chronic heart failure (CHF) has been proved. Decreased HRV after MI is independent as well as ejection fraction (EF) sudden cardiac death risk factor. In patients with SDNN value below 50 ms high risk of cardiac death is observed. SDNN should be estimated on 7th day of MI to evaluate patients with high risk of sudden cardiac death. In patients after MI with ventricular tachycardia (VT) before VT decreased HRV is described. During MI beneficial influence of infarct-related artery patency on HRV is observed. HRV correlates with EF and infarct site too. HRV in patients with CHF correlates with EF and functional severity of CHF. Correlation between decreased HRV and increased mortality in CHF has been shown. In diabetic patients decreased HRV is observed. Following diabetes examination of HRV is useful to estimate early phase of autonomic neuropathy. Increase HRV parameters is observed in the course of beta-adrenolytic and converting enzyme inhibition treatment. In other diseases, including heart transplantation prognostic value of HRV and its clinical significance are still investigated.

[Radiofrequency catheter ablation of two accessory pathways in patients with WPW Syndrome]. / Ablacja pradem o czestotliwosci radiowej dwóch dróg dodatkowych u chorego z zespolem preekscytacji.

In 10-30% patients with WPW syndrome more than one accessory pathway in electrophysiology study is observed. These patients make a group of higher atrial fibrillation and coming next ventricle fibrillation risk. We present the 39 years old patient with symptomatic WPW syndrome, without preexcitation signs in ECG at rest. In medical history--palpitations was observed from childhood with one episode of atrial fibrillation with high ventricle response required cardioversion. Electrophysiology study: without preexcitation signs at rest, two ortodromic AV reentrant tachycardias were induced--200 and 166/min. Two accessory pathways were diagnosed, left lateral and left midseptal. Radiofrequency catheter ablation of both accessory pathways was made during tachycardia, first lateral, next septal. In six month follow-up the patient was asymptomatic.

[Holter monitoring in diagnosis of syncope]. / Monitorowanie holterowskie w diagnostyce omdlen.

Thirty two patient with a history of brief unconsciousness underwent a constant ECG monitoring with Holter's technique for 24-72 hours. Syncope was noted in 16 patients. Cardiac arrhythmia was a cause of unconsciousness in 14 patients whereas no such a pathology was seen in the remaining two patients. No syncope was seen during ECG monitoring in 16 patients. Loss of consciousness was found in the majority of patients monitored for 72 hours. This technique may be valuable in the diagnosis of syncope, especially when it appears during ECG monitoring.

[A case of paroxysmal ventricular tachycardia surgically treated based on electrophysiological diagnosis]. / Przypadek napadowego czestoskurczu komorowego leczonego chirurgicznie w oparciu o diagnostyke elektrofizjologiczna.

There was presented a case of recurrent ventricular tachycardia in the patient after myocardial infarction. Considering uneffective pharmacotherapy and several cardiac arrests, the patient underwent guided endo-cardiotomy based on complex electrophysiological diagnostics (including intraoperative examination). Postoperative period was uncomplicated. There were no recurrences of ventricular tachycardia during 18-month follow-up.

[Comparative evaluation of the results of Holter monitoring and programmed ventricular stimulation in patients with ischemic heart disease]. / Ocena porównawcza wyników badania holterowskiego i programowanej stymulacji komór u osób z choroba niedokrwienna serca.

24-hour ECG Holter monitoring and programmed ventricular stimulation were performed in 81 patients (64 males and 17 females aged 35-65). No ++anti-arrhythythmic agents nor beta-blockers were administrated. 58 patients suffered from myocardial infarction in the past, and 38 had a history of ventricular tachycardia. Right atrial and ventricular stimulation (in 7 patients also left ventricular stimulation) was performed using stimuli of a 2 ms pulse width. 24-hour ECG Holter monitoring was recorded on a magnetic tape from two bipolar precordial leads. Both examinations results were compared to assess correlation between ECG Holter monitoring parameters and inducibility of VT or VF by programmed stimulation. Significant correlation was stated among occurrence of: 1) spontaneous sustained ventricular tachycardia and induced by stimulation monomorphic sustained VT (p less than 0.005) as well as estimated both sustained and nonsustained VT (p less than 0.010) 2) spontaneous nonsustained VT and induced by stimulation sustained or nonsustained monomorphic VT (p less than 0.025). There was no correlation between spontaneous ventricular arrhythmias estimated by Lown and Wolf's classification and possibility to induce monomorphic VT as well as between any of ECG Holter monitoring parameters and polymorphic VT or ventricular fibrillation induced by stimulation. Aggressiveness extent of stimulation protocol necessary to induce monomorphic VT was similar in patients with or without VT recorded by Holter method.