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B D Gonska

Publications and source records attributed to B D Gonska.

62 records · Page 4Linked to original sources
PubMed1985

[Long-term electrocardiography: value and reliability of various systems].

25 years after the introduction of ambulatory electrocardiography four concepts are available: the conventional Holter-ECG, computer-based systems, entire ECG recording in miniaturized form and the event recorder. In contrast to visual analysis with the aid of an arrhythmia computer a more precise and quantitative evaluation of long-term ECG is possible. The reliability of a computer-based system is indicated by its sensitivity, positive predictive accuracy and reproducibility of automatic analysis. Only few of the computerized systems have been repeatedly tested on a company independent basis using these criteria in a representative number of patients, with frequent arrhythmias, and with a separate documentation of false negative, false positive and true positive events. Data available so far show that a reasonable reliability is possible, but 100% remains the exception to the rule. Thus, there is no complete automatic analysis of cardiac arrhythmias, and corrections by the physician are mandatory. This is further emphasized by the fact that only a part of all possible arrhythmias may be identified by computer whereas the other part has to be evaluated by visual control. In this context entire ECG recording is helpful, as an isolated method, however, it cannot be recommended, since the miniaturized ECG prevents analysis of subtle details and provides no quantitative data. Event recorders rely exclusively on the accuracy of the portable arrhythmia detector. Due to the concept of discontinuous ECG recording evaluation of this accuracy is pronounced problematic. Only by changing to the continuous recording mode does validation of the event recorder become possible. The first data demonstrate that the reliability of real-time analysis by the portable arrhythmia detector is not superior to highspeed analysis by the arrhythmia computer. Thus, quality control is necessary when using the event recorder as it is with continuous long-term ECG. However, there are significant limitations: with discontinuous ECG recording false negative events are not documented, separation of false positive from correct positive findings is restricted to the limited recording capacity (12-120 min real time) and the short ECG samples (6-12s) do not allow verification of sustained arrhythmias. Furthermore, questions regarding arrhythmias, ST-segment changes and pacemaker dysfunctions unidentifiable by computer remain unanswered with the use of the event recorder. For these reasons, continuous ambulatory electrocardiography providing complete data for every kind of analysis is still the standard method.(ABSTRACT TRUNCATED AT 400 WORDS)

Ambulatory Care↗
PubMed1984

[Determination of left atrial size. Comparison between echocardiographic and radiological determination].

The size of the left atrium was determined echocardiographically and radiologically in 66 patients with mitral valve disease, grade I-IV (New York Heart Association classification). Angiocardiography served as the reference. The echocardiographic determination was both by M-mode and two-dimensional, the radiological one was from the postero-anterior films (after Higgins), as well as from the lateral pictures. There was good agreement between the two echocardiographic methods and a good correlation of the two with cine-angiographic measurements (r = 0.82-0.99; P less than 0.001). But there was a poorer, although still statistically significant correlation of the radiologically determined atrial size with the echocardiographic and angiocardiographic measurements (r = 0.47-0.56; P less than 0.001). Thus M-mode and two-dimensional echocardiography is the more sensitive method for determining the size of the left atrium.

Adult↗
PubMed1984

[Primary angiosarcoma of the heart--3 case reports and a review of the literature].

Three cases of primary angiosarcoma of the heart diagnosed intra vitam are reported. A review of the literature with 118 described cases is given, with special reference to localization, clinical symptoms, diagnostic procedures, and prognosis. Modern diagnostic procedures make it possible to diagnose cardiac tumors in the living patient, but prognosis remains poor.

Adult↗
PubMed1984

[Significance of the detection of echocardiographic vegetation for the clinical course and prognosis of infectious endocarditis].

52 patients with infective endocarditis and manifestations on 62 valves were examined by echocardiography between January 1978 and May 1983. In 34 patients (65%) vegetations were visible at least on one valve, in 10 patients (19%) the result was doubtful and in 8 patients (16%) no vegetations could be seen. In a comparison of echocardiographic and intraoperative or autopsy findings, with doubtful results left out, the over-all sensitivity was 96%, specifity 44% and reliability 83%. There was no statistically significant difference in echocardiographic results between patients who were operated upon or treated medically. Patients with positive echocardiographic vegetations had no statistically significant higher risk of embolism. Morphological aspects of the vegetations had no influence on clinical course and prognosis either. All 12 patients (23%) who died had positive echocardiographic vegetations. Yet the difference from the surviving group was not significant. Hence, echocardiography is a sufficiently sensitive and reliable method for the detection of vegetations in patients with infective endocarditis. However, echocardiographic findings alone are of no consequence in medical or surgical treatment, arterial embolization or prognosis.

Adolescent↗
PubMedDate not supplied

Indirect parasympathomimetic activity of the class III antiarrhythmic substance D/L-sotalol in vitro: reversible inhibition of cholinesterase isoenzymes from blood and the human central nervous system.

Inhibitory effects of the class III antiarrhythmic compound D/L-sotalol on acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes of both erythrocytes and the human caudate nucleus and on serum cholinesterase (ChE; EC 3.1.1.8) were studied in vitro using a spectrophotometric kinetic assay with acetylthiocholine (ASCh) as substrate. Sotalol concentrations in the assays varied from 0.32 to 3.2 mM. All isoenzymes studied were inhibited by D/L-sotalol in a reversible and concentration-dependent manner. Double reciprocal plots of the reaction velocity against varying ASCh concentrations revealed that D/L-sotalol reduced substrate affinity (apparent Michaelis constant, KM, increased) of serum ChE, but did not change the enzyme's maximal rate of ASCh hydrolysis (Vmax). Thus, D/L-sotalol inhibition of serum ChE was of the competitive type (rate constant for reversible competitive inhibition: Ki = 0.51 mM). In contrast, D/L sotalol reduced the maximal reaction velocity of the AChE isoenzyme from the central nervous system (caudate nucleus), but had no influence on substrate affinity of the enzyme (KM with ASCh unchanged) indicating purely non-competitive inhibition kinetics (rate constant of reversible non-competitive inhibition: Ki = 0.44 mM). D/L-sotalol inhibition of erythrocyte AChE was of mixed competitive/non-competitive type (Ki = 0.31 mM, Ki = 0.49 mM). Non-competitive D/L-sotalol inhibition of caudate nucleus AChE and the non-competitive component of erythrocyte AChE inhibition cannot be overcome by increased concentrations of the cholinergic transmitter acetylcholine (ACh). Peak D/L-sotalol plasma levels as described in the literature for both humans (15 microM) and experimental animals (dogs: 18 microM; rats: 260 microM) as well as maximal myocardial concentrations of the substance (dogs: 46 microM; rats: 478 microM) are in the range of about 2% to 100% of the sotalol inhibition rate constants determined in the present paper for cholinesterase isoenzymes in vitro. Thus, D/L-sotalol inhibition of ACh hydrolysis in vivo may contribute to both the well known antiarrhythmic potential and proarrhythmic side effects of the compound.

Animals↗
PubMedDate not supplied

Indirect parasympathomimetic activity of metoclopramide: reversible inhibition of cholinesterases from human central nervous system and blood.

Inhibitory effects of the dopamine D2-receptor antagonistic benzamide compound metoclopramide (MCP) on acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes of both erythrocytes and human caudate nucleus and on human serum cholinesterase (ChE; EC 3.1.1.8) were studied in vitro using a spectrophotometric assay with acetylthiocholine (ASCh) as substrate. MCP concentrations in the assays varied from 0.30 microM to 0.15 mM. All isoenzymes studied were inhibited by metoclopramide in a concentration-dependent manner. MCP inhibition of AChE and ChE isoenzymes was not time-dependent and of the reversible type. Double reciprocal plots of the reaction velocity against varying ASCh concentrations revealed that, for AChE isoenzymes of erythrocytes and of the caudate nucleus, MCP reduced both maximal reaction velocity (Vmax) and substrate affinity (apparent Michaelis constant, KM, increased). Thus, MCP inhibition of both AChE isoenzymes was of mixed competitive/non-competitive type. MCP constants for reversible competitive (Ki) and non-competitive (Ki) inhibition could be determined for erythrocyte AChE (Ki = 10 microM; Ki = 70 microM) and caudate nucleus AChE (Ki = 9.3 microM; Ki = 82 microM). In contrast to MCP inhibition of AChE isoenzymes, the type of reversible MCP inhibition of human serum ChE depended on substrate concentration. If substrate concentration exceeded 0.2 mM, MCP inhibition was of mixed competitive/non-competitive type (Ki = 0.19 microM; Ki = 1.4 microM). MCP inhibition was of uncompetitive type, if substrate concentration was below 0.2 mM (Ki(u) = 1.0 microM). The mixed-type MCP inhibition of cholinesterase isoenzymes, because of its non-competitive component, can only partially be overcome by increased concentrations of the cholinergic transmitter acetylcholine (ACh). Since, with intravenous infusions, peak MCP plasma concentrations in humans reach 4 microM, MCP inhibition of ACh hydrolysis in vivo may contribute both to prokinetic and anti-emetic actions of the substance and to its extrapyramidal side effects.

Acetylcholinesterase↗
PubMedDate not supplied

Empirical versus tested antitachycardia pacing in implantable cardioverter defibrillators: a prospective study including 200 patients.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden cardiac death. The objective of this study was to evaluate whether testing of antitachycardia pacing (ATP) for induced ventricular tachycardias (VTs) at predischarge examination can predict ATP success during follow-up. METHODS AND RESULTS: The study covers 200 consecutive patients who received ICD implants from June 1991 through December 1995. All underwent electrophysiological testing. In 54 patients (ATP tested, group T), ATP terminated induced VTs successfully. In 146 patients (empirically programmed ATP, group E), only ventricular fibrillation could be induced, including 18 with unsuccessful ATP attempts for induced VTs. Disregarding the results of ATP testing, the same ATP scheme was programmed in all patients: three attempts of autodecremental ramp with 81% of the VT cycle length, with 8 to 10 pulses. During a follow-up of 20.4 +/- 10 months, 95% of 3819 spontaneous VTs were successfully terminated with ATP in 42 patients of group T. In group E, 90% of 1346 spontaneous VTs in 81 patients were terminated with ATP. Acceleration after ATP occurred in 2% in group T versus 5% in group E. The success for all episodes in individual patients was > or =90% in >60% of the ATP tested and empirically programmed patients. CONCLUSIONS: The results of this 200-patient prospective study comparing tested versus empirical ATP show high success (95% versus 90%) for VT termination, with low rates of acceleration. ATP is safe and very effective and should be programmed "on" in all patients regardless of the predischarge EP inducibility.

Adult↗