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Tachyarrhythmia following scorpion envenomation might be an indication for anti venin therapy. We present a case of an unusual cardiotoxic response to Leiurus quinquestriatus ('yellow scorpion') venom-second degree atrio-ventricular block (Mobitz type 1). We review the biological activities of L. quinquestriatus' venom and the arrhythmia's possible pathophysiology. The question arising from this case is the therapeutic approach to cardiotoxicity and bradyarrhythmias induced by scorpion envenomation-mainly, the indication for anti serum therapy.

We report on four elderly women in whom carbamazepine was suspected of inducing sinus node dysfunction (3 patients) and atrioventricular block (1 patient). Patients were treated with carbamazepine, 200 to 600 mg a day, for trigeminal neuralgia (n = 3) or epilepsy (n = 1). After 1 to 16 months of carbamazepine therapy, these patients were admitted to our emergency room because of bradyarrhythmia. Their conduction disturbances on electrocardiographic monitoring disappeared immediately after the cessation of carbamazepine intake. Provocation tests were performed on three patients. Because of renal insufficiency, one patient could not undergo the provocation test. Her carbamazepine clearance was markedly decreased. Carbamazepine induced sinus arrest in two patients within 48 hours after intake, but did not induce atrioventricular block in the remaining patient. In two patients, computer simulation of carbamazepine pharmacokinetics was performed and disclosed a clear-cut relationship between the plasma concentration of carbamazepine and the frequency of sinus arrest. During the test, the maximum plasma carbamazepine concentration in these two patients did not exceed the therapeutic range. However, it did exceed the range in the one with a negative test. Our results suggest that careful monitoring of ECG and plasma drug concentration is required with carbamazepine therapy, especially in elderly women.

Centrally acting cholinergic agents are currently reported to increase blood pressure in various species through the stimulation of muscarinic cholinoceptors. Moreover, several cardiovascular adverse effects have been reported from clinical studies. The aim of this study was to investigate the effects of tacrine, an acetylcholinesterase inhibitor which has been reported to have therapeutic potential in Alzheimer's disease, on blood pressure and two vasopressor systems (sympathetic and vasopressinergic) in Beagle dogs. Intravenous (i.v.) tacrine (2 mg kg(-1)) induced, in conscious and anesthetized dogs, an increase in systolic and diastolic blood pressure, accompanied by bradycardia. This increase was dose-dependent with a peak effect at 1.5 min following administration. Tacrine also induced an increase in noradrenaline, adrenaline and vasopressin plasma levels. Pretreatment with the muscarinic receptor antagonist, atropine (2 mg kg(-1), i.v.), abolished the pressor response to i.v. injection of tacrine while pretreatment with the peripheral muscarinic receptor antagonist, methylscopolamine (0.2 mg kg(-1), i.v.), did not alter the increase in blood pressure. Similarly, noradrenaline and adrenaline changes in plasma levels were not modified by methylscopolamine but were abolished by atropine pretreatment. A similar tendency although not significant was observed for vasopressin plasma levels. The present results demonstrate that in dogs, tacrine (2 mg kg(-1), i.v.) stimulates central muscarinic cholinoceptors to increase blood pressure through activation of the two components of the sympathetic nervous system (i.e., neuroneuronal noradrenergic and the neurohormonal adrenergic pathways) as well as through increasing noradrenaline, adrenaline and vasopressin plasma levels.

Objectives: Assess the efficacy of an anesthesic cream for pacemaker implantations., Methods: Percutaneous anesthesia was studied in a series of permanent pacemaker transvenous implantations. The anesthesic cream composed of a mixture of lidocaine and prilocaine was applied precisely over operative areas after marking the skin. Percutaneous anesthesia should be applied 2 hours before entering the operating room., Results: This percutaneous local anesthesia was perfectly effective for simple replacement procedures. At first implantations, it was used alone in 4 out of 10 cases while intradermal injections were needed to anesthetize the deep layers in the other patients. Serum concentrations indicate very low levels which are tolerated very well., Conclusion: Alone or combined with lidocaine infiltration, the use of an anesthesic cream is safe and effective in transvenous pacemaker surgery.

Objectives: Premature infants are known to be at risk for oxygen (O2) desaturation and/or apnea in car seats. Since 1990, the American Academy of Pediatrics has recommended a period of monitoring in car seats before hospital discharge for infants born at < 37 weeks gestation. The objective of this report is to determine if selected term infants are also at risk for O2 desaturation, apnea, or bradycardia while in an infant car seat., Methods: MetroWest Medical Center is a community hospital with a level II neonatal unit. Term infants who in the judgment of their pediatrician were felt to be at risk for O2 desaturation or apnea were monitored for a 90-minute period in a car seat and observed for transcutaneous O2 desaturation, apnea, or bradycardia. In addition, several infants who were admitted to the pediatric inpatient unit after discharge from the nursery were monitored in a similar fashion., Results: Eight of 28 monitored infants (28.6%) had a period of O2 desaturation < 90%. In addition, five of 28 monitored infants (17.8%) had borderline results (O2 saturation, 90 to 93%). All four infants monitored because of genetic syndromes had abnormal results. O2 desaturation was also observed in two term infants who had been observed to be apneic by a parent after discharge from the nursery., Conclusions: In selected circumstances (eg, genetic disorders or observed apnea) term infants may be at risk for O2 desaturation in an upright car seat and monitoring these infants in car seats before nursery discharge should be considered. Because not all infants at risk for O2 desaturation can be identified at birth, an alternative approach would be to recommend, unless medically contraindicated (eg, gastroesphogeal reflux when supine), that infants should routinely be transported in a supine position car seat in the early months of life.

Repetitive polysomnograms were recorded between 40 weeks post-conceptional age and 6 months in a total of 49 infants, 19 healthy preterm infants, 14 normal term infants, and 16 subsequent siblings of infants who died of sudden infant death syndrome (SIDS). These nighttime recordings lasted 2-4 hours, except at 3 months when an overnight 12-hour recording was performed. Obstructive apneas (OA) > 3 seconds were divided into 3 categories: 1) clear obstructive, 2) mixed and 3) unclear because of movement artifacts. More than half belonged in category 3 and were excluded from further analysis unless accompanied by a transient episode of bradycardia (TEB), defined as heart rate < or = 100 beats per minute. Each OA with TEB was also examined for changes in transcutaneous oxygen tension (PtcO2). Most pauses were brief (median, 4 seconds), the longest (27 seconds) seen only once in the youngest premature infant. The majority of OA were accompanied by heart rate accelerations. The number of clear obstructive and mixed apneas was similar. The scores were combined to calculate a density (number per 100 minutes of recording). OA were not common: Their density decreased from 2 in 100 minutes at 40 weeks in the preterm to once every 300 minutes (5 hours) in the 6-month-old term infant. Ten percent of the OA were accompanied by TEB. Of these, 10% were accompanied by a PtcO2 decrease of > 10 mm Hg. OA with TEB followed a nonmonotonic curve, the highest percentage of infants showing this pattern at the age of highest risk for SIDS. Minor differences among study groups were confined to less movements with OA in subsequent siblings and an earlier peak incidence of OA with TEB in prematures, compared to normal term infants. OA were seen in all study groups, were self-limited, and apparently were devoid of pathological consequences.

A 82-year-old woman was admitted to hospital because of heart failure, vomiting, and pain in the right upper abdomen. During the past three months she had received treatment with 0.07 mg digitoxin twice daily. The ECG showed sinus bradycardia with intermittent complete sinoatrial block. On the basis of the history, clinical presentation and ECG findings digitalis intoxication was suspected. Digitoxin level was 65.23 ng/ml--far beyond the therapeutic range. Laboratory examinations revealed a marked thrombocytopenia (25,000/microliters). The patient was placed on cholestyramine (4g three times daily) to accelerate intestinal excretion of digitoxin. As there were no life-threatening complications there was no indication for treatment with digitalis-specific antibodies. On the 6th day after discontinuation of digitoxin treatment the platelet count showed a marked rise and returned to normal values as from the 12th day.

In order to create and evaluate a model sensitive to QT-dependent proarrhythmic effects of drugs, a long QT syndrome was produced in chronically instrumented dogs with bradycardia and hypokalemia. Bradycardia (mean cycle length: 1495 +/- 78 msec) was provided by permanent atrioventricular block and hypokalemia (K+ = 2.6 +/- 0.05 mmol/l) by high doses of diuretics. To evaluate that model, six of these conscious dogs were subjected to quinidine, flecainide, lidocaine, propranolol and sotalol infusions. In crossover design, drugs were infused i.v. at rates allowing stable and nontoxic drug plasma levels during the experiment. Four-lead ECGs were recorded for arrhythmias for 30 min before (base line) and 75 min after onset of infusion. Ventricular cycle length was increased dramatically by sotalol, lidocaine and propranolol (+618 +/- 192, +388 +/- 125 and +329 +/- 114 msec, respectively) and QT interval was increased by sotalol, quinidine and flecainide (+56 +/- 8, +31 +/- 7.9 and +20 +/- 5.7 msec, respectively). Quinidine and sotalol, but not flecainide, propranolol or lidocaine, exhibited significant arrhythmogenic activities. During quinidine infusion, most dogs exhibited some ventricular arrhythmias whose most severe forms were runs of ventricular tachycardia. These arrhythmias were suppressed by pacing at high rates. During sotalol infusion, five out of six dogs exhibited typical "torsades de pointes." This incidence was not related to the slowing effects of sotalol on idioventricular pacemakers, because a similar incidence was obtained in five complementary dogs paced at 40 bpm. It could be related to dose, because torsades de pointes occurred only once in another group of five dogs receiving half the dose used in the controlled study. Only quinidine and sotalol, but not propranolol, flecainide or lidocaine, are clinically associated to torsades de pointes. They were also the only drugs associated with proarrhythmic events in the present study, a fact suggesting that QT-dependent arrhythmogenic effects of drugs can be reliably evaluated in conscious hypokalemic dogs with complete atrioventricular block.

To analyse the effects of apnoea and bradycardia on the oxygen saturation (SaO2) of preterm infants and to make recommendations for apnoea alarm limits, polygraphic recordings were made on 89 occasions of 27 preterm infants; 1029 apnoeic episodes were analysed. Reduction in SaO2 was positively correlated with duration of apnoea, but the scatter of results was such that reductions in SaO2 of up to 40% occurred with apnoeas of less than 10 seconds duration. The median initial SaO2 was significantly lower in those episodes that resulted in bradycardia (92% compared with 95%), and there was also a significantly greater reduction in median SaO2 (9% compared with 5%). This study illustrates the difficulty of setting alarm limits for the detection of apnoea. We suggest that rather than simply detecting apnoea it is more appropriate to monitor heart rate and SaO2 in infants with recurrent apnoea.

Near infrared spectroscopy has been used to assess the effects of bradycardia and hypoxia on the cerebral circulation in the premature neonate. The technique is well tolerated and can be applied in almost any infant. Continuous monitoring of changes in cerebral oxygenated, deoxygenated, and total haemoglobin is possible. Total haemoglobin is analogous to cerebral blood volume; thus information on circulatory changes as well as oxygenation state can be obtained. Twenty five babies had cerebral monitoring carried out using this technique. During episodes of hypoxia, both spontaneous and induced, impairment of haemoglobin oxygenation within the brain was detected together with an overall increase in the total mean haemoglobin concentration, which was 0.8 x 10(-2) mmol/l. Bradycardia with apnoea also led to impairment of cerebral oxygenation, and to a rapid fall in the concentration of total mean haemoglobin to 1.4 x 10(-2) mmol/l, which was followed in some cases by an increase to above the resting value on recovery of the heart rate to a mean of 0.7 x 10(-2) mmol/l. These disturbances to total haemoglobin concentration represent abnormalities of cerebral blood volume that may be implicated in the pathogenesis of neonatal cerebral injury.

Plasma atrial natriuretic factor, aldosterone, renin activity, and antidiuretic hormone were studied in low output heart failure syndromes: cardiogenic shock in ten patients with acute myocardial infarction of the anterior wall (first group), hypovolemic shock after melena from peptic ulcer in ten subjects (second group), and hypotension with bradycardia syndrome in ten patients with acute myocardial infarction of the inferior wall (third group). Circulating atrial natriuretic factor in patients with cardiogenic shock (102.4 +/- 7.4 pg/ml) was significantly higher than in healthy volunteers matched for sex and age (8.4 +/- 0.3 pg/ml). In these patients there was a positive correlation between atrial natriuretic factor and central venous pressure values. Atrial natriuretic factor and central venous pressure values in the second and third groups were within normal range. Plasma aldosterone was high in all groups, plasma renin activity was elevated in the first and third groups, and high antidiuretic hormone was observed in the first and second groups. These findings indicate that in low output heart failure syndromes only hemodynamic changes affecting the atria stimulate atrial natriuretic factor release. No correlations were found between plasma atrial natriuretic factor and other hormones. In particular, high atrial natriuretic factor levels in the patients with cardiogenic shock did not inhibit release of aldosterone, renin, or antidiuretic hormone. It may be surmised that in these patients the hemodynamic effects override the inhibitory effects of atrial natriuretic factor.

The authors present a patient with carbamazepine-induced bradycardia-tachycardia syndrome, a rare type of drug-induced sinus node dysfunction. In this case, they established a clear-cut relationship between plasma carbamazepine concentration and the frequency of sinus arrests, following episodes of supraventricular tachycardia. As the pharmacological analysis of drug-induced sinus node dysfunction by concurrent ECG monitoring is very limited, the findings give an insight into the mechanism of this disorder.

Obstructive jaundice is often listed among the causes of sinus bradycardia. The latter is usually attributed to the effect of bile salts on the sino-atrial node. The purpose of this study was to determine the frequency of sinus bradycardia (heart rate less than 50/min) in 50 patients with severe or moderate cholestasis, and to relate sinus rate and intracardiac conduction to total serum conjugated bile acid concentrations. The latter were measured using a solid-phase 125I radio-immunoassay. The mean sinus rate (+/- SD) in the patients was 74.1 +/- 11.6/min (range 47-100/min). One patient had a sinus rate of less than 50/min and 2 had rates of 50-60/min. The mean total serum conjugated bile acid concentration was 251.1 +/- 198.8 mumol/l (range 13-1000 mumol/l). There was no correlation in individual patients between total serum bile acid concentration and sinus rate (r = +0.097), P-R interval (r = +0.210) or corrected Q-T interval (r = -0.085). We conclude that sinus bradycardia is not a feature of obstructive jaundice and that high serum bile acid concentrations do not exert a slowing effect on the sino-atrial node.

Umbilical venous plasma concentrations of beta-endorphin in 20 premature and 30 mature newborn infants after vaginal delivery or elective caesarean section were determined by specific RIA. In the premature infants the beta-endorphin levels after vaginal and abdominal delivery were significantly higher than in mature newborns. Our data indicate that for premature infants the delivery is more stressful and therefore most likely the release of beta-endorphin from the pituitary is more pronounced. Since high opioid levels can cause respiratory and circulatory difficulties, premature infants are exposed to risk of these problems.

The relationship between 5-HT contents in peripheral blood and power density among workers exposed to microwave or high frequency radiation in the workshops were studied. At the same time, systems and disorder of central nervous system and cardiovascular system were examined. The results of study showed that the average 5-HT content in whole blood for high frequency radiation exposure group was lower than that of the control, but without statistical significance. Value for the microwave exposure group was significantly lower than that of the control (P less than 0.01). The 5-HT content of mechanical maintainers exposed to microwave of high frequency radiation were all lower than the contents of their corresponding control groups (P less than 0.01). But for the mechanic operators as compared with their corresponding control, no significant difference was found (P greater than 0.05). The power density exposed by the maintainers of both tested groups were all higher than that of the operators. The 5-HT contents in the whole blood were inversely proportional to the power density of microwave and high frequency groups. The incidence of neurasthenic syndrome, unsymmetric skin temperature in both limbs and hypotension was higher in the microwave and high frequency radiation groups than that in the control group. The incidence of bradycardia and some abnormal items of electrocardiograph in the microwave group was obviously greater than that in high frequency group, which may be related to different frequency exposed for these two exposure groups. Whether it is related to the contents of 5-HT needs further investigation.

Thrombosis in the right atrium or ventricle is a rare complication of permanent endocardial pacing in adults. To the best of our knowledge, this complication has not been previously reported at all in the pediatric age group. We report on a case of a 7-year-old boy who had large left ventricular thrombi that occurred during permanent endocardial electrical stimulation. Subsequent pulmonary emboli complicated congestive heart failure in this patient. As a diagnostic approach, echocardiography and pulmonary perfusion scintigraphy were used. We comment on possible causes of this serious complication and suggest hemorrheological and platelet activation studies in patients with permanent endocardial pacing.

We present three cases with abnormal fetal heart rate patterns and cordocentesis umbilical venous blood gas analyses. Conflicting heart rate patterns and cordocentesis and postnatal blood gas analyses prompt questions with regard to abnormal fetal heart rate pattern interpretation and suggest that cordocentesis blood gas analysis aids perinatal management only as a reflection of fetal status at sampling time.

The aim of this paper was to study plasma atrial natriuretic factor, renin activity, aldosterone and antidiuretic hormone in low-output heart failure syndromes such as cardiogenic shock, hypovolemic shock and hypotension with bradycardia syndrome. A total of 30 patients were investigated: 10 with cardiogenic shock due to acute myocardial infarction of the anterior wall (systolic and diastolic blood pressure 56.0 +/- 3.7/40.5 +/- 2.0 mmHg; heart rate 119.7 +/- 1.2 beats/min; central venous pressure 16.2 +/- 0.6 cmH2O) (I group), 10 with hypovolemic shock induced by melena in peptic ulcer (systolic and diastolic blood pressure 74.5 +/- 1.5/57.5 +/- 1.7 mmHg; heart rate 111.0 +/- 1.4; central venous pressure 6.3 +/- 0.5 cmH2O) (II group), 10 with hypotension with bradycardia syndrome which occurred in patients during acute myocardial infarction of the inferior wall (systolic and diastolic blood pressure 71.9 +/- 2.0/58.0 +/- 2.6 mmHg; heart rate 52.0 +/- 2.2 beats/min; central venous pressure 4.6 +/- 0.4 cmH2O) (III group). Plasma atrial natriuretic factor values were measured using radioimmunoassay after chromatographic pre-extraction; plasma renin activity, aldosterone and antidiuretic hormone values were calculated using radioimmunoassay. Circulating atrial natriuretic factor was significantly (p less than 0.01) higher in patients with cardiogenic shock (102.4 +/- 7.4 pg/ml) than in healthy volunteers (8.4 +/- 0.3 pg/ml). In the former there was a positive correlation between atrial natriuretic factor and central venous pressure values. Atrial natriuretic factor and central venous pressure values in the IInd and IIIrd groups of patients were in the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)