Biomedical subjects
Publications and source records attributed to A Frigy.
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UNLABELLED: Syncope is defined as a transient, self-limited loss of consciousness. It is an important cause of morbidity in general population and the vasovagal syncope (VVS) is a common clinical problem which often leads to hospital admission, multiple office visits, and performing of many diagnostic tests. Head-up tilt table testing (HUTT) is a widely used diagnostic tool, with proved efficiency in diagnosing the many types of VVS. The aim of our study was to assess the efficacy of the HUTT with sublingual nitroglycerin (NTG) challenge for the diagnosis of vasovagal syncope. PATIENTS AND METHODS: The study groups consisted of 72 patients (37 women, 35 men), mean age (+/-SD) 38.5 +/- 15.7 years, referred to our clinic for syncope of unknown origin and 16 healthy volunteers as control subjects (9 women and 7 men) with a mean age 26 +/- 6.5 years and no history of syncope. The HUTT protocol was performed in the morning after an overnight fast, with a 15 minutes supine equilibration phase followed by a 30 minutes drug free tilt phase at an angle of 70 degrees. If no positive response was recorded, 400 micrograms of NTG spray were given sublingually and the HUTT continued for 20 minutes. RESULTS: The HUTT was positive in 58 patients (80.5%) and negative in 14 (19.5%) while in the control subjects 4 (25%) had positive HUTT response. The sensitivity of the HUTT protocol with nitroglycerin challenge used in our study was 81% and the specificity was 75% (p<0.0001). CONCLUSION: The described HUTT protocol appears to be a simple and efficient tool for the diagnosis of syncope associated with normal ECG and no signs of organic heart disease. The sublingual nitroglycerin challenge was safe to use and showed no side effects while keeping the sensitivity and specificity of the test to an accepted level.
The efficacy of sublingual verapamil (Verapabene, 40 mg) in acute control of high ventricular rate was assessed in 20 patients with chronic atrial fibrillation (AF) of ischemic origin (class NYHA II and III). The effect on irregularity of the rhythm was also studied using time domain parameters of heart rate variability. Four ECG recordings (before, and at 10, 30 and 60 minutes after the administration), of 10 minutes each, were performed in every patient in basal conditions. The parameters were compared using paired t-test and Wilcoxon's test. Mean heart rate became significantly lower (p = 0.0064) after 10 minutes, and reached progressively the lowest value after 60 minutes (from the initial 112.9 beats/min to 90.6 beats/min, after 60 minutes, p < 0.0001). The irregularity parameters (SDNN--from 114.7 ms to 148.6 ms, rMSSD--from 152 ms to 205.9 ms) and the NNmin interval (from 353 ms to 404.5 ms) increased significantly after 30 and 60 minutes (p < 0.0001), but the frequency corrected irregularity (coefficient of variability) remained unchanged (p > 0.4). Sublingually administered verapamil proved to be an efficient alternative in acute control of rapid ventricular rate in AF. The method has the advantage to be applicable by a properly instructed patient itself.
The principal theoretical, methodological and clinical aspects of heart rate variability (HRV) analysis are reviewed. This method has been developed over the last 10 years as a useful noninvasive method of measuring the activity of the autonomic nervous system. The main components and the functioning of the computerized rhythm-analyzer system developed by our team are presented. The system is able to perform short-term (maximum 20 minutes) time domain HRV analysis and statistical analysis of the ventricular rate in any rhythm, particularly in atrial fibrillation. The performances of our system are demonstrated by using the graphics (RR histograms, delta RR histograms, RR scattergrams) and the statistical parameters resulted from the processing of three ECG recordings. These recordings are obtained from a normal subject, from a patient with advanced heart failure, and from a patient with atrial fibrillation.