Prolonged and fractionated right atrial electrograms during sinus rhythm in patients with paroxysmal atrial fibrillation and sick sinus node syndrome

Intraatrial catheter mapping of the right atrium was performed during sinus rhythm in 92 patients: Group I = 43 control patients without paroxysmal atrial fibrillation or sick sinus node syndrome; Group II = 31 patients with paroxysmal atrial fibrillation but without sick sinus node syndrome; and Group III = 18 patients with both paroxysmal atrial fibrillation and sick sinus node syndrome. Atrial electrograms were recorded at 12 sites in the right atrium. The duration and number of fragmented deflections of the atrial electrograms were quantitatively measured. The mean duration and number of fragmented deflections of the 516 atrial electrograms in Group I were 74 +/- 11 ms and 3.9 +/- 1.3, respectively. The criteria for an abnormal atrial electrogram were defined as a duration of greater than or equal to 100 ms or eight or more fragmented deflections, or both. Abnormal atrial electrograms were observed in 10 patients (23.3%) in Group I, 21 patients (67.7%) in Group II and 15 patients (83.3%) in Group III (Group II versus Group I, p less than 0.001; Group III versus Group I, p less than 0.001). The mean number of abnormal electrograms per patient with an abnormal electrogram was 1.3 +/- 0.7 in Group I, 2.5 +/- 1.9 in Group II and 3.5 +/- 2.5 in Group III (Group I versus Group II, p less than 0.01; Group II versus Group III, p less than 0.05). A prolonged and fractionated atrial electrogram characteristic of paroxysmal atrial fibrillation can be closely related to the vulnerability of the atrial muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic treatment of Zenker's diverticulum

BACKGROUND

The most important aspect of the surgical management of Zenker's diverticulum is probably the cricopharyngeal myotomy. Endoscopic diverticulotomy can be performed with a needle-knife papillotome, which allows simultaneous myotomy of the upper esophageal sphincter.

METHODS

Since 1978, 47 patients (28 men and 19 women 51 to 81 years of age) underwent endoscopic diverticulotomy. Most patients underwent more than one treatment session (mean value 2.2). The procedure was performed with sedation. Tubes were not used, and oral intake of food was begun the first day after the operation.

RESULTS

Forty-five (95.74%) patients had no dysphagia or only occasional, mild dysphagia during the postoperative course. No fistula, no recurrent laryngeal paralysis, and no deaths occurred.

CONCLUSION

Endoscopic diverticulotomy seems to be a good choice of therapy at least for patients with associated diseases that increase surgical risk.

Laparoscopic management of choledocholithiasis

The authors report on a group of 114 patients with common bile duct (CBD) stones who were treated by laparoscopic surgery. Management through the cystic duct was considered the first option. Choledochotomy was used for those patients in which the cystic approach was not possible or was unsuccessful. Transcystic lithotripsy was considered for patients with CBD stones in disproportion with the size of the cystic duct. Laparoscopic antegrade sphincterotomy was indicated as a drainage procedure. The transcystic approach was used in 89.5% of the patients; choledochotomy was used in 6.2%; and both ways were used in 4.3%. Different procedures were used, including mechanical and electrohydraulic lithotripsy, choledochotomy with T-tube or endoprostheses drainage, laparoscopic sphincterotomy, end-to-end common bile duct anastomosis, and choledochoduodenum anastomosis. One of the patients was in the 21st week of pregnancy. The laparoscopic approach to choledocholithiasis was successfully performed in 94.8% of the patients. Mean hospital stay was 1.7 days. There was a 6.2% incidence of complications and the mortality rate was 0.9%. In 84.3% of the patients, the transcystic approach was used successfully, with a complication rate of 4.9% and a mean hospital stay of 1.6 days. Three patients were converted to open surgery early in this series. Thus far, one patients has presented residual CBD stones. The results obtained suggest that laparoscopic common bile duct exploration is a technically feasible procedure, with low complication and mortality rates, although it requires adequate selection of patients and a variety of techniques and types of equipment.

Laparoscopic reoperations after failed and complicated antireflux operations

Nineteen patients underwent laparoscopic reoperations for failed or complicated antireflux operations from a total of 248 patients with gastroesophageal reflux disease who had been operated on by this approach. Sixteen had been submitted to open surgery and three to laparoscopic surgery over a period ranging from 5 days to 31 years before the study. Three patients had been submitted to two open antireflux surgeries previously. Seventeen patients had recurrent reflux esophagitis after different types of surgeries, and two patients presented with gastric strangulation after fundoplication. The causes of recurrence were: slipped total fundoplications (3), disruption of total and partial fundoplications (6), too-tight total fundoplication (1), too-low (gastric) partial fundoplication (1), Allison procedure (1), partial fundoplication and paraesophageal hernia (2), and unknown (3). The laparoscopic approach was used in 18 patients and a laparoscopic-thoracoscopic approach in 1. The procedures included laparoscopic total fundoplications (11), partial fundoplications (4), transhiatal esophagectomy (1), Collis-Nissen (1), Roux-en-Y gastrectomy and thoracoscopic vagotomy (1), and intrathoracic fundoplication (1). One patient was converted to open surgery. Intraoperative complications included 1 pneumothorax, 1 gastric perforation, and 1 esophageal perforation during the introduction of a Maloney dilator. Mean operative time was 210 min, ranging from 140 to 320 min. Mean hospital stay was 3.1 days after treatment of failed operations and 22 days after treatment of complications. Postoperative complications included subcutaneous infection (1), gastric fistula (1), and liver hematoma (1). The results have been excellent and good in 84.3% of the patients after a mean follow-up of 13 months. We concluded that laparoscopic reoperations are technically feasible with good preliminary results provided that the mandatory expertise is available.

Intra-atrial conduction delay and fragmented atrial activity in patients with paroxysmal atrial fibrillation

To examine the electrophysiologic characteristics of paroxysmal atrial fibrillation (PAF), we studied intra-atrial conduction delay and fragmented atrial activity during premature stimulation of high right atrium in the following four groups: Group I (n = 25), patients without PAF and without sick sinus syndrome (SSS); Group II (n = 22), patients with PAF but without SSS; Group III (n = 10), patients without PAF and with SSS; Group IV (n = 6), patients with PAF and SSS. Intra-atrial conduction delay was the increase in the interval (from the stimuli to the coronary sinus electrogram) observed with early premature beats greater than or equal to 20 ms compared with that of basic rhythm. Fragmented atrial activity was defined as disorganized atrial activity greater than or equal to 150% of the duration of high atrial activity of basic beats recorded. The conduction delay zone (CDZ) and fragmented atrial activity zone (FAZ) were significantly wider in Groups II, III and IV than in Group I. There were no significant differences in either CDZs or FAZs among Groups II, III and IV. Thus, the widening of CDZs and/or FAZs are characteristic of PAF and SSS. CDZ and FAZ may be good indices of development of PAF in patients without SSS.

Different distribution of abnormal endocardial electrograms within the right atrium in patients with sick sinus syndrome

BACKGROUND

Prolonged and fractionated right atrial endocardial electrograms are characteristic of paroxysmal atrial fibrillation (idiopathic or associated with sick sinus syndrome). The distribution of these abnormal atrial electrograms within the right atrium and the way it is related to the likelihood that patients with sick sinus syndrome will develop paroxysmal atrial fibrillation was studied.

METHODS

Endocardial catheter mapping of the right atrium during sinus rhythm was performed in 41 control patients with normal sinus node function and without paroxysmal atrial fibrillation, in 33 patients with sick sinus syndrome but without tachycardia, and in 27 patients with sick sinus syndrome and paroxysmal atrial fibrillation (group 3). The bipolar electrograms were recorded at 12 sites in the right atrium and an abnormal atrial electrogram was defined as lasting > or = 100 ms and/or showing eight or more fragmented deflections.

RESULTS

1195 atrial endocardial electrograms were assessed and quantitatively measured. In patients with sick sinus syndrome and paroxysmal atrial fibrillation 54% of the abnormal atrial electrograms were recorded from the high right atrium, 28% from the mild right atrium, and 18% from the low right atrium. However, in patients with sick sinus syndrome without tachycardia 78% of the abnormal atrial electrograms were recorded from the high right atrium and 22% from the mid right atrium. No abnormal electrograms were recorded from the low right atrium.

CONCLUSIONS

In patients with sick sinus syndrome without tachycardia abnormal atrial electrograms generally came from the high right atrium but in patients with sick sinus syndrome and paroxysmal atrial fibrillation abnormal atrial electrograms were more widely distributed in the right atrium. In patients with sick sinus syndrome the greater the extent of the compromised atrial muscle, the greater the likelihood that paroxysmal atrial fibrillation will develop.

Experimental endoscopic repair of gastric perforations with an omental patch and clips

BACKGROUND

The omental patch is a standard surgical treatment of gastroduodenal ulcer perforation. This is a report of an experimental method for endoscopic repair of anterior gastric perforations with an omental patch developed by using a porcine model.

METHODS

A standardized gastric perforation was created in 10 pigs. The omentum was pulled into the gastric lumen and fixed endoscopically to the muscularis propria layer of the stomach with metallic clips.

RESULTS

The postoperative course was normal in 9 animals. An ulcer was evident at the site of repair at follow-up endoscopy. At autopsy, the omentum was adherent to the external side of gastric wall. One animal died with peritonitis, presumably because the muscularis propria layer could not be seen during the procedure, and the clips attached the omentum only to the mucosa.

CONCLUSIONS

Endoscopic repair with an omental patch appears to be an effective procedure for closure of gastric perforations.

Inactivation of Saccharomyces cerevisiae by ultrasonic irradiation

We have investigated the inactivation of Saccharomyces cerevisiae (yeast cells) by ultrasonic irradiation. The amplitude on the vibration face contacting the sample solution was used as an indication of the ultrasonic power intensity. The effects of the amplitude on the vibration face and the initial cell numbers on the sonolytic inactivation of yeast cells have been investigated using a horn-type sonicator (27.5 kHz). The inactivation of the yeast cells by ultrasonic irradiation shows pseudo first-order behavior. The inactivation rate constant varied from 0.0007 to 0.145 s(-1) when the amplitude on the vibration face was in the range of 1-7 microm(p-p). The change in the inactivation rate constant as a function of the amplitude on the vibration face was similar to that of the OH radical formation rate under the same conditions. The threshold of this sonicator was 3 microm(p-p) with the amplitude on the vibration face. The initial cell numbers (from 10(2) to 10(5) mL(-1)) had an influence on the inactivation of the yeast cells by ultrasonic irradiation. The inactivation rate constants varied from 0.023 to 6.4 x 10(-3) s(-1), and the inactivation by ultrasonic irradiation was fastest at the lowest initial cell numbers. In a squeeze-film-type sonicator (26.6 kHz), 90% inactivation of the yeast cells was achieved by ultrasonic irradiation for 60 min.

Impaired left ventricular filling in borderline hypertensive patients without cardiac structural changes

To determine the effect of borderline hypertension on left ventricular diastolic performance, 16 patients with borderline hypertension who did not have left ventricular hypertrophy and 16 age-sex-matched patients with normotension of similar age and body mass index were investigated. Pulsed Doppler echocardiography was used to record left ventricular filling signals at rest and immediately after supine ergometer exercise. All subjects had normal left ventricular structure and systolic function. At rest the borderline hypertension group in comparison with the normotension group had a depressed peak velocity of early filling (E) (44 +/- 7 vs 54 +/- 10 cm/sec; p < 0.01), no enhanced peak velocity of late filling (A) (52 +/- 8 vs 50 +/- 11 cm/sec; not significant), and a reduced E/A ratio (0.9 +/- 0.2 vs 1.1 +/- 0.3; p < 0.05). Atrial filling time and preejection period were similar in the two groups. The effect of exercise on left ventricular filling velocity in patients with borderline hypertensive resembled that in those with normotension. Percentage changes in E (+14% +/- 12% vs +14% +/- 13%) and A (+13% +/- 8% vs 11% +/- 12%) were equivalent, suggesting a preserved diastolic reserve for exercise in the borderline hypertension group. In conclusion, borderline hypertension appears to be predictive of early filling impairment, and a late filling compensative mechanism is not yet apparent. These findings in borderline hypertension without apparent cardiac damage call for clinical attention to prevent further deterioration in cardiac function.

Prediction of a fatal atrial fibrillation in patients with asymptomatic Wolff-Parkinson-White pattern

Paroxysmal atrial fibrillation (PAF) in patients with manifest WPW syndrome can be a life-threatening arrhythmia by deterioration into ventricular fibrillation. In patients with asymptomatic WPW pattern, the first PAF may lead to ventricular fibrillation or sudden death. Therefore, the purpose of this study was to predict a fatal PAF in patients with asymptomatic WPW pattern. The patient population was divided into two groups: (1) 145 patients with manifest WPW syndrome, excluding intermittent ones (32 with an episode of PAF, 49 with AV reciprocating tachycardia alone, and 64 without any episode of paroxysmal tachyarrhythmia), and (2) mixed group of patients with and without WPW syndrome (36 with an episode of PAF and 66 without PAF). The results were as follows: (1) (a) out of 32 patients with WPW syndrome and PAF, 8 patients were observed to have both the shortest preexcited R-R interval of less than 200 msec during PAF and the shortest antegrade effective refractory period of the accessory pathway (ERP-AP) of less than 250 msec, 7 of whom had dizziness or syncope during PAF and 2 died suddenly during the follow-up period; (b) 21 (32.8%) out of 64 patients with asymptomatic WPW pattern showed the shortest antegrade ERP-AP less than 250 msec; (2) patients with PAF had a higher tendency to develop repetitive atrial firing (RAF), as well as fragmented atrial activity (FAA), which were induced using programmed atrial stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiologic properties of atrial muscle in paroxysmal atrial fibrillation

The electrophysiologic properties of atrial muscle were studied by programmed atrial stimulation in 42 patients with paroxysmal atrial fibrillation (PAF) and in 53 control patients without PAF. Single premature atrial stimulation was given at the right atrial appendage following 8 basic stimuli with a basic cycle length of 500 ms. Repetitive atrial firing (RAF) was defined as the occurrence of 2 or more successive premature atrial activations following single premature atrial stimulation. Fragmented atrial activity (FAA) was defined as an increase by more than 75% of the duration of the atrial electrogram in response to a single premature stimulation. Interatrial conduction delay was defined as an increase of the conduction time by more than 50 ms in response to a single premature stimulation. RAF was induced in 26 of 42 patients (61.9%) with PAF and in 14 of 53 control patients (26.4%). FAA and interatrial conduction delay were elicited in 69.0 and 80.9% of patients with PAF and in 34.0 and 56.6% of control patients, respectively. In 16 patients with PAF in whom RAF was not induced, FAA developed in 11 patients (68.8%). In 88.1% of 42 patients with PAF and in 41.5% of 53 controls, RAF or FAA, or both, were elicited by atrial premature stimulation. It is concluded that the incidence of RAF and FAA were significantly higher in patients with PAF than in the control group, and the induction of RAF or FAA, or both, was closely related to the vulnerability of the atrial muscle to atrial fibrillation.

Electrophysiological abnormalities of the atrial muscle in patients with manifest Wolff-Parkinson-White syndrome associated with paroxysmal atrial fibrillation

We investigated the electrophysiological properties of the atrial muscle in 33 patients with manifest Wolff-Parkinson-White syndrome. Group I consisted of 13 patients with paroxysmal atrial fibrillation and group II consisted of 20 patients without paroxysmal atrial fibrillation. The anterograde and retrograde effective refractory periods of the accessory pathway and the inducibility of atrioventricular reciprocating tachycardia were not significantly different between the two groups. Endocardial electrograms, obtained by right atrial catheter mapping, were recorded during sinus rhythm from 12 sites of the right atrium in 12 of the 13 group I patients and in all group II patients. An abnormal atrial electrogram was defined as 100 msec or longer in duration, and/or the occurrence of eight or more deflections. Ten (83%) of the 12 group I patients had abnormal atrial electrograms, while only two (10%) of the 20 group II patients had abnormal atrial electrograms, and the difference was significant (P less than 0.01). Thirty-six (26%) of the total 139 electrograms obtained from 12 group I patients and two (1%) of the total 199 electrograms obtained from 20 group II patients fulfilled the criteria for an abnormal atrial electrogram, and the difference was significant (P less than 0.01). The fragmented atrial activity zone, interatrial conduction delay zone, and repetitive atrial firing zone obtained by right atrial extrastimulation were significantly wider in group I than in group II, respectively. It was concluded that electrical abnormalities of the atrial muscle may play an important role in the occurrence of paroxysmal atrial fibrillation in patients with Wolff-Parkinson-White syndrome.

Results of the routine use of a modified endoprosthesis to drain the common bile duct after laparoscopic choledochotomy

BACKGROUND

One hundred eighty-one patients were submitted to laparoscopic common bile duct exploration.

METHODS

A transcystic approach was used in 147 patients, choledochotomy in 14, and both in 20. The indications to perform a choledochotomy included stones larger than 20 mm, stones proximal to the cystic duct entrance, and cases in which the transcystic duct approach proved impossible or unsuccessful.

RESULTS

The common bile duct was drained by a T-tube in four patients, by laparoscopic sphincterotomy in one, by laparoscopic choledochoduodenostomy in one, and by a 10 Fr endoprosthesis in 28. The stent placement was technically feasible in all patients but one. The biliary drainage was adequate. Mean hospital stay was 2.1 days. Complication was limited to one umbilical infection and one self-limited biliary leak.

CONCLUSIONS

The procedure proved to be technically simple, safe, and efficient, and resulted in a low morbidity rate and short hospital stay.

Reliability of QT intervals as indicators of clinical hypercalcemia

Reliability of corrected QT intervals (QoTc, QaTc, and QeTc) as indicators of clinical hypercalcemia was assessed in 14 hypercalcemic patients. Hypercalcemia was severe to extreme (serum calcium 14.9 to 22.8 mg/dl) in 11, moderate (13.4 mg/dl) in 1, and mild (12.2 and 11.8 mg/dl) in 2 patients. QT intervals during hypercalcemia were compared with those during normocalcemia either before or after development of hypercalcemia. QeTc interval showed neither significant correlation with serum calcium nor any consistent pattern of change with development of hypercalcemia or normalization of serum calcium. In contrast, QoTc and QaTc intervals shortened with development of hypercalcemia and returned toward normal with normalization of serum calcium in all the patients, and showed significant correlation with serum calcium (QoTc: r = -0.77, p less than 0.001, n = 35; QaTc: r = 0.82, p less than 0.001, n = 35). QaTc was short (less than 0.30 s) in all the ECGs in severe and moderate hypercalcemia and in 2 of the 5 ECGs in mild hypercalcemia. Combination of short QoTc (less than 0.18 s) and short QaTc was found to be highly specific for, and was present in 65% of ECGs, in moderate and severe hypercalcemia. Combination of normal QoTc (greater than 0.18 s) and normal QaTc (greater than 0.30 s) was not observed in moderate or severe hypercalcemia. We conclude that QoTc and QaTc intervals are reliable indicators of clinical hypercalcemia.

Prorenin is sorted into the regulated secretory pathway independent of its processing to renin in mouse pituitary AtT-20 cells

A native human prorenin and a mutant of its processing site (Arg-43 to Gln) were expressed in mouse pituitary AtT-20 cells which process prorenin to renin and have both regulated and constitutive secretory pathways. The native prorenin was processed to renin and secreted in a regulated manner. Although the mutant precursor was not processed, it was also secreted in a regulated manner. These results suggest that prorenin is sorted into the regulated pathway, stored in secretory granules and released by stimulus whether it is processed to renin or not.

Arrhythmogenic properties of the ventricular myocardium in cardiomyopathic Syrian hamster, BIO 14.6 strain

STUDY OBJECTIVE

Incidence of spontaneous cardiac arrhythmias and inducibility of ventricular arrhythmias in the cardiomyopathic hamster, BIO 14.6 strain, were examined.

DESIGN

A 3 min electrocardiogram (ECG) was recorded weekly to 50 weeks of age. Programmed ventricular stimulation was then performed with single and double ventricular premature stimuli during both sinus rhythm and ventricular pacing, and with brief bursts of ventricular pacing to induce ventricular arrhythmias.

EXPERIMENTAL MATERIAL

19 male cardiomyopathic and 10 age matched normal hamsters from 16 to 50 weeks were used for recording the 3 min ECG; 11 cardiomyopathic and 10 normal hamsters aged 50 to 55 weeks were used for the induction of ventricular arrhythmias.

MEASUREMENTS AND MAIN RESULTS

Spontaneous and sporadic ventricular premature contractions were documented in 8.3% of 218 ECGs from the cardiomyopathic hamsters between the ages of 30 and 46 weeks, whereas no ventricular arrhythmia was recorded in normal hamsters throughout the entire follow up period. Non-sustained ventricular tachycardia (NSVT) was induced in 7/11 cardiomyopathic hamsters by single ventricular premature stimulus. Either NSVT or ventricular fibrillation was induced in all cardiomyopathic hamsters with a significantly prolonged intraventricular conduction delay and refractory period. In contrast, neither NSVT nor ventricular fibrillation was induced in normal hamsters.

CONCLUSION

This study provides the first evidence of the high arrhythmogenicity of the ventricles in cardiomyopathic hamsters.

Electrophysiological abnormalities of the atrial muscle in patients with sinus node dysfunction without tachyarrhythmias

The duration and the number of fragmented deflections of the right atrial electrograms were assessed and quantitatively measured in 74 patients who underwent endocardial catheter mapping during sinus rhythm. The bipolar electrograms were recorded at 12 sites in the right atrium. An abnormal atrial electrogram was defined as a duration of 100 ms or longer, and/or 8 or more fragmented deflections, according to our previous criteria. The patients were divided into two groups. The control group consisted of 41 age-matched patients with normal sinus node function and without paroxysmal atrial fibrillation. The study group comprised 33 patients with sinus node dysfunction but without tachyarrhythmias. Abnormal atrial electrograms were observed in 8 (19.5%) control patients, and in 16 (48.5%) sinus node dysfunction patients; p < 0.02. The total number of abnormal electrograms was 14 (2.89%) of 483 atrial electrograms in controls, and 36 (9.38%) of 384 in the study group; p < 0.0002. The mean duration (75.6 +/- 17) and the mean number of fragmented deflections (4.1 +/- 2) of the total atrial electrograms in the sinus node dysfunction group was significantly greater than that in controls (70.9 +/- 11 and 3.6 +/- 1, respectively); p < 0.01. The mean number of abnormal electrograms per patient in the study group (1.06 +/- 1.8) was significantly higher than that in the control group (0.3 +/- 0.8); p < 0.05. These data suggest that: (1) there is a significantly greater electrophysiological abnormality of the atrial muscle in patients with sinus node dysfunction but without paroxysmal atrial fibrillation than in age-matched controls, and (2) not only the sinus node but also the atrial muscle is electrophysiologically altered in patients with sinus node dysfunction but without tachyarrhythmias.

Changes in T wave morphology during hypercalcemia and its relation to the severity of hypercalcemia

The effect of hypercalcemia on T wave morphology, polarity, and amplitude was studied in 14 patients with a primary diagnosis of malignant lymphoma (8 patients), adult T-cell leukemia (5 patients), and Hodgkin's disease (1 patient). Hypercalcemia was severe to extreme in 11 (14.9-22.8 mg/dl), moderate in 1 (13.4 mg/dl), and mild in 2 (11.8 and 12.2 mg/dl) patients. Ten of the 11 patients (91%) with severe hypercalcemia showed inverted, biphasic, and notched T waves, mainly in the chest leads. Notched T waves were observed in all 10 of these patients in anterior to lateral, mid to lateral, or lateral chest leads. Biphasic and/or inverted T waves in anterior or anterior to midchest leads were present in 4 of these 10 patients who had extreme hypercalcemia (greater than 16 mg/dl). Changes in T wave morphology were not observed in moderate or mild hypercalcemia. T wave amplitude showed significant inverse correlation with serum calcium (T mV vs Ca, r = -0.60, p less than 0.001; T/R ratio vs Ca, r = -0.68, p less than 0.001; n = 35). Decrease in T wave amplitude was marked in severe hypercalcemia (p less than 0.0001) and moderate hypercalcemia, but there was no change in mild hypercalcemia. Changes in T wave morphology, polarity, and amplitude either appeared with development of hypercalcemia or disappeared with normalization of serum calcium level. It was concluded that in addition to shortening the QT interval, severe to extreme hypercalcemia can cause development of inverted, biphasic, or notched T wave with a marked decrease in amplitude of T waves.

Primary aldosteronism aggravated during peripartum period

Two cases are reported of a 30-year-old and of a 28-year-old Japanese women with primary aldosteronism in whom metabolic and blood pressure abnormalities were aggravated during peripartum period. The characteristic findings in 2 present cases are as follows; 1) lower blood pressure during pregnancy, 2) elevated blood pressure during peripartum period, and 3) after parturition, serum potassium decreased, and the blood pressure elevated. The reason why the hypertension and hypokalemia associated with primary aldosteronism were ameliorated during pregnancy was thought to be due to the increased secretion of progesterone. Furthermore, the rapid recurrence of symptoms, increase in blood pressure, and hypokalemia in the post-partum period could be related to elevated prolactin and decreased progesterone levels.

Specific 125I-endothelin-1 binding sites in the atrioventricular node of the porcine heart

The quantitative receptor autoradiographic method we used revealed that specific 125I-endothelin-1 binding sites are highly concentrated in the atrioventricular node of the porcine heart. 125I-Endothelin-1 binding to the atrioventricular node, interatrial and interventricular septa was displaced by unlabeled endothelin-1 with Kd values of 53 pM, 2.03 nM and 3.48 nM, respectively. Knowledge of the existence of specific 125I-endothelin-1 binding sites in the porcine heart helps with understanding the physiology of endothelin, a possible endogenous Ca2+ channel agonist.

Asystole with syncope following strenuous exercise in a man without organic heart disease

A 29-year-old man without organic heart disease who had a history of six episodes of syncope following sudden cessation of strenuous exercise over the last 18 years was reported. Resting electrocardiogram and 24-hour electrocardiographic monitoring did not show any rhythm disturbance or ischemic changes. Sinus node recovery time, sinoatrial conduction time and A-V conduction were normal on electrophysiologic study. Asystole with syncope occurred immediately following sudden cessation of strenuous exercise and following release of intrathoracic pressure during Valsalva's maneuver performed after subcutaneous administration of 0.5 mg of epinephrine. However, Master's single two-step test and Valsalva's maneuver performed without epinephrine could not evoke asystole. It was assumed from these results that transient overactivity of the autonomic nervous system and sympathetic-parasympathetic interactions were the underlying factors responsible for the occurrence of asystole following sudden cessation of strenuous exercise in the present case.