Biomedical subjects
Publications and source records attributed to E Caraşca.
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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.
Electrical activity of the sinoatrial node was recorded on bipolar intracavitary leads at superior vena caval-right atrial junction in ten patients. These recordings may be important for practical purposes, but they still have many limitations concerning the amount of the atrial potentials which can be recorded together with sinoatrial potential.
Fourteen patients with atrial flutter (AFL) and rapid atrial tachycardia (AT) (8 AFL type I, 2 AFL type II and 4 AT) were treated with endocavitary atrial pacing (EAP). In 10 patients no antiarrhythmic agent was during this study and in 4 patients digoxin and/or verapamil was administered before. Conversion to sinus rhythm was successfully achieved in 7 patients, 50% (4 AFL type I and 3 AT). Primary success rate (return to sinus rhythm either immediately or after < 10 min of atrial fibrillation) was 71% (5/7) (2 AFL type I and 3 AT); delayed success (conversion to sinus rhythm in > 10 min, but < 24 h) was observed in 2 cases (29%) with AFL type I. At five patients AFL was converted in stable atrial fibrillation (4 AFL type I and 1 AFL type II). EAP failed to terminate the arrhythmia in 1 patient with uncommon AFL (type II) and 1 case with AT. EAP included single extrastimuli, coaction, single decremental atrial extrastimuli and incremental atrial pacing (burst) during AFL or AT. In conclusion, EAP is a method with few complications and has efficacy for converting AFL and rapid AT sinus rhythm or to atrial fibrillation.
Monophasic action potential (MAP) represents an extracellular recording of electrical potentials variations produced simultaneously by several cells. Even if it does not represent the real cellular action potential, monophasic action potential generally reproduces with accuracy that aspect, being useful especially in the assessment of myocardial repolarisation phases. Monophasic action potential recording was performed with a quadripolar catheter designed by Franz; the quality of recordings was good and the procedure is safe. In clinical electrophysiology, monophasic action potential may be helpful in the study of certain aspects that cannot be evaluated adequately by standard electrophysiological techniques. The study was performed on six patients, in drug-free state. The duration of monophasic action potential at 90% of repolarisation and the atrial effective refractory period, at three basic cycle lengths (600, 500 and 400 msec) were determined. Both monophasic action potential duration at 90% of repolarisation and the atrial effective refractory period shortening at short cycle length and a linear correlation between these two parameters were seen. We conclude that the correlation between monophasic action potential duration and the effective atrial refractory period may be a simple and useful model to characterise in vivo the electrophysiologic profile of antiarrhythmic drugs.
Sixty patients of whom 51 with old myocardial infarction--30 with late ventricular potentials and 30 without--were followed up for 5 years. The late ventricular potentials were recorded using an original method. During the follow-up period, in the group, with late ventricular potentials, sudden death was recorded in 6 patients and episodes of ventricular tachycardia in 2. No sudden death occurred in the patients without late ventricular potentials. The prognostic value of this simple, noninvasive technique is emphasized.
During a period of 20 years, 8 patients with atrial fibrillation, without other cardiac abnormalities, resistant to electroconversion, but successfully defibrillated with quinidine, were examined. All were males, aged 40 to 50 years, working with electric current and exposed for many years to frequent electric shocks. The authors consider that chronic exposure to electric current induces a special form of atrial fibrillation, resistant to electric conversion. The inefficiency of the electroshock therapy in such cases might be explained by the increase of transthoracic impedance consecutive to repeated electrocutions.
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Digitalis glycosides have an antiarrhythmic effect in atrial fibrillation, as defibrillatory drugs. These drugs could be classified in a group of antiarrhythmic drugs close to the ventricular defibrillating drugs recently proposed. The reasons for this opinion are shown in this work.
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For the functional estimation of artificial pacemakers, we have used two techniques: chest-wall stimulation and transesophageal stimulation. Transesophageal stimulation was always effective in inhibiting the generator, and it was used when chest-wall stimulation was ineffective. These two tests can be easily performed and are of remarkable usefulness in the follow-up of patients with permanent pacemaker.
In order to eliminate the first pass through the liver where the drug is deactivated, 80 mgs verapamil was given in sublingual way in a) 10 patients with supraventricular tachycardias where in 7 instances sinus rhythm was obtained after 15-30 minutes, b) in 18 patients with atrial fibrillation and in 5 with atrial flutter with rapid ventricular rate, where a significant slowing down of ventricular rate was obtained after 20 minutes. The sublingual way of verapamil administration is a simple, effective and safe procedure in the treatment of tachyarrhythmias.
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Precordial thump is considered a useful manoeuver in cardiac arrest and ventricular tachycardia. On ecg recordings we have observed that the precordial thump has always been followed by an atrial or ventricular depolarization (premature beats), which is responsible for the cardiac electric activity enhancement and for the interruption of reentrant mechanism in ventricular and supraventricular tachycardias.
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A hypothesis of transition from atrial fibrillation to sinus rhythm in close relation with monophasic action potential duration is proposed. The first way: the prolongation of the right atrial refractoriness reduces the wave fronts below a critical number and their collision terminates the arrhythmia. The second way: progressive shortening of refractoriness at a critical level with block and collision of wave fronts.