A variant of long QT syndrome manifested as fetal tachycardia and associated with ventricular septal defect

Two patients with a novel variant of long QT syndrome are described. The clinical course was characterised by an in utero onset of ventricular tachycardia and atrioventricular block (at 26 and 30 weeks' gestational age, respectively), and an association with a ventricular septal defect. Studies of both patients' families identified relatives with prolonged QT interval, syncope, or sudden death. One patient died of intractable ventricular tachycardia at 4 days old. The other received beta blocker treatment and a pacemaker. She died suddenly at the age of 10 months. The unique association with ventricular septal defect and the malignant clinical course warrants further molecular diagnosis of this novel variant of long QT syndrome.

Usefulness of intravenous propofol anesthesia for radiofrequency catheter ablation in patients with tachyarrhythmias: infeasibility for pediatric patients with ectopic atrial tachycardia

General anesthesia is sometimes required during radiofrequency catheter ablation (RFCA) of various tachyarrhythmias because of an anticipated prolonged procedure and the need to ensure stability during critical ablation. In this study, we examine the feasibility of using propofol anesthesia for RFCA procedure. There were 150 patients (78 male, 72 female; mean age 30 years, range 4-96 years) in the study. Electrophysiologic study was performed before and during propofol infusion in the initial 20 patients and was performed only during propofol infusion in the remaining 130 patients. In the initial 20 patients, propofol infusion increased the sinus rate and facilitated AV nodal conduction. The accessory pathway effective refractory period, as well as the sinus node recovery time, atrial effective refractory period, and ventricular effective refractory period were not significantly changed. There were 152 tachyarrhythmias in 150 patients (24 atrial flutter, 31 AV nodal reentrant tachycardia, 68 AV reciprocating tachycardia, 12 ventricular tachycardia, and 17 atrial tachycardia). Most (148/152) tachycardias remained inducible after anesthesia and RFCA was performed uneventfully. However, in four of the seven pediatric patients with ectopic atrial tachycardia, the tachycardia terminated after propofol infusion and could not be induced by isoproterenol infusion. Consequently, RFCA could not be performed. Intravenous propofol anesthesia is feasible during RFCA for most tachyarrhythmias except for ectopic atrial tachycardia in children.

Activated neutrophils induce hyperpermeability and phosphorylation of adherens junction proteins in coronary venular endothelial cells

The endothelial adherens junction is formed by complexes of transmembrane adhesive proteins, of which beta-catenin is known to connect the junctional protein vascular endothelial (VE)-cadherin to the cytoskeleton and to play a signaling role in the regulation of junction-cytoskeleton interaction. In this study, we investigated the effect of neutrophil activation on endothelial monolayer integrity and on beta-catenin and VE-cadherin modification. Treatment of cultured bovine coronary endothelial monolayers with C5a-activated neutrophils resulted in an increase in permeability as measured by albumin clearance across the monolayer. Furthermore, large scale intercellular gap formation was observed in coincidence with the hyperpermeability response. Immunofluorescence analysis showed that beta-catenin and VE-cadherin staining changed from a uniform distribution along the membrane of control cells to a diffuse pattern for both proteins and finger-like projections for beta-catenin in neutrophil-exposed monolayers. Correlatively, there was an increase in actin stress fiber formation in treated cells. Finally, beta-catenin and VE-cadherin from neutrophil-treated endothelial cells showed a significant increase in tyrosine phosphorylation. Our results are the first to link neutrophil-mediated changes in adherens junctions with intercellular gap formation and hyperpermeability in microvascular endothelial cells. These data suggest that neutrophils may regulate endothelial barrier function through a process conferring conformational changes to beta-catenin and VE-cadherin.

Role of O6-alkylguanine-DNA alkyltransferase in protecting against cyclophosphamide-induced toxicity and mutagenicity

Cyclophosphamide is used to treat a wide range of human malignancies. However, it is also a known carcinogen associated with induction of therapy-related leukemia and bladder cancer. The DNA repair protein, O6-alkylguanine-DNA alkyltransferase (AGT), protects cells from the toxic and mutagenic effects of O6-alkylating agents. We report here the contribution of AGT in protecting against the toxic and mutagenic effects of cyclophosphamide. CHO cells transduced with wild-type human AGT (CHO(AGT)) and pcDNA3 (CHOpcDNA3) were treated with activated cyclophosphamide derivatives, 4-hydroperoxycyclophosphamide (4-HC), 4-hydroperoxydidechlorocyclophosphamide (4-HDC), a progenitor of acrolein, and phosphoramide mustard (PM). The results show that CHO(AGT) is 7- or 20-fold less sensitive to the toxic effects of 30 microM 4-HC or 300 microM 4-HDC, respectively, than CHOpcDNA3 cells as measured by cell survival using a colony-forming assay. CHO(AGT) cells treated with 20 microM 4-HC or 200 microM 4-HDC produced 4- or 7-fold lower mutation frequency as measured at the HPRT locus than CHOpcDNA3 cells treated with the same dose of drugs. At 30 microM acrolein, the cell survival for CHO(AGT) was 30% compared with 18.7% for CHOpcDNA3. The mutation frequency of acrolein at the same dose was 57 mutants/10(6) cells in CHOpcDNA3 compared with no mutants in CHO(AGT). In contrast, CHO(AGT) and CHOpcDNA3 cells treated with PM had similar survival curves and exhibited no difference in mutation frequency. The present study demonstrates that AGT plays an important role in protecting against the toxic and mutagenic effect of cyclophosphamide and suggests that acrolein, not PM, is responsible for generating the toxic and mutagenic lesion(s) protected by the AGT protein.

Submucosal esophageal dissection--a rare case report

The severity of submucosal dissection is intermediate between transmural rupture and mucosal tear in the esophagus. We describe a case of submucosal dissection of the esophagus with characteristic features of mucosal bridge endoscopically and "double-barreled" in radiography. The patient was successfully treated by intermittent esophageal tamponade of 5-day duration using a Sengstaken-Blackmore tube, and total parenteral nutrition. His course was uneventful in a follow-up period of 5 years.

Accelerated healing of Dacron grafts seeded by preclotting with autologous bone marrow blood

> Studies have suggested that bone marrow-derived cells in the circulation may have the capacity and potential to endothelialize and heal vascular graft surfaces. We have investigated whether accelerated endothelialization could be achieved for Dacron grafts seeded by preclotting with bone marrow blood (BMB). Five 8 mm x 6 cm Dacron grafts seeded and preclotted with BMB and four controls preclotted with peripheral blood were implanted in the descending thoracic aorta (DTA) of mongrel dogs for 2 and 4 weeks. Two additional BMB DTA grafts were studied for 3 months. Five pairs of BMB and control grafts (4 mm x 6 cm) were bilaterally implanted into the carotids of dogs for 1 week and five pairs for 4 weeks. All grafts remained patent. BMB seeding/preclotting was a simple, effective method to accelerate early graft endothelialization without increasing thrombogenicity. Further studies are needed before clinical application can be recommended.

Morphology and histology of human and canine internal thoracic arteries

BACKGROUND

We evaluated human and canine internal thoracic arteries (ITAs) to determine whether the latter is valid for studies relevant to clinical use.

METHODS

We studied 19 human ITAs obtained from 1 female and 14 male victims of recent fatal accidents who had no evidence of cardiovascular disease (mean age = 39+/-19 years; range = 15 to 79 years), and ITAs of 21 randomly-selected mongrel dogs of both sexes, weighing 18-40 kg (average = 24.3+/-5.7 kg). Specimens were fixed in formalin at a controlled pressure of 120 mm Hg, before extensive assessment that included intimal thickening, condition of the internal elastic lamina, and number of medial elastic lamellae and vasa vasorum.

RESULTS

The canine morphology and histology were similar to the human ITAs, but there was no intimal hyperplasia, and the media and adventitia were thinner (ITAs of humans older than 40 years had significant increases in medial thickness, as well as in overall length). Morphologically and histologically, the left and right canine ITAs were almost completely the same.

CONCLUSIONS

Canine ITAs are valid for bilateral comparative studies and are a useful tissue source and model for clinically-relevant experimental studies.

Sequence of the V. parahaemolyticus gene for cytoplasmic N, N'-diacetylchitobiase and homology with related enzymes

The nucleotide sequence of the gene encoding the cytoplasmic N, N'-diacetylchitobiase [EC 3.2.1.14] from Vibrio parahaemolyticus (ATCC #27969) has been determined. The deduced peptide sequence of this unusual beta-hexosaminidase surprisingly shows minimum evolutionary relationship to two other reported N, N'-diacetylchitobiases from vibrios, except in highly conserved regions which are also homologous to lysosomal beta-hexosaminidases from eukaryotes including humans. In contrast, the two other beta-hexosaminidases from vibrios with reported sequences are much more closely related to each other. This novel 85 kDa cytoplasmic glycosyl hydrolase with restricted specificity participates in the high level utilization of chitin-derived 2-deoxy-2-acetamido-D-glucose (GlcNAc) by vibrios as one of two parallel pathways for the metabolism of N,N'-diacetylchitobiose [Bassler, B.L., Yu, C., Lee, Y.C., and Roseman, S. (1991) J. Biol. Chem. 266, 24276-24286]. These pathways use chitin-binding proteins for the adherence of the bacterial chitinase to the substrate, and an extracellular chitinase and a periplasmic chitodextrinase to produce N,N'-diacetylchitobiose. The V. parahaemolyticus cytoplasmic N,N'-diacetyl-chitobiase reported herein appears to be a unique protein, lacking a signal sequence, and genetically distant from other known chitinoclastic beta-N,N'-diacetyl-hexosaminidases. This is consistent with its limited substrate specificity to small GlcNAc terminated oligosaccharides and its cytoplasmic rather than periplasmic localization.

Clinical and experimental demonstration of complete healing of porous Dacron patch grafts used for closure of the arteriotomy after carotid endarterectomy

A clinical porous Dacron patch graft used for closure after carotid endarterectomy was explanted 24 hr postmortem during autopsy. There had been no TIAs or stroke postoperatively, and the cause of death was congestive heart failure. The graft had been implanted for 25 months. The specimen had a very clean surface, was completely incorporated by full-wall tissue ingrowth, and the flow surface was covered with well-organized neointima containing endothelial cells and smooth muscle cells, as confirmed by immunological studies. For comparison, animal experiments were performed. In both the clinical and experimental specimens the carotid patches were patent without neointimal compromise of the lumen, and their healing patterns were similar, with endothelium on the flow surface.

Balloon dilatation for critical pulmonary stenosis

This study was conducted to investigate the outcome of balloon valvuloplasty for critical pulmonary stenosis in young infants. During a 6.2-year period between January 1992 and February 1998, 34 infants with critical pulmonary stenosis, aged 1 to 58 days (16.8+/-16.6 days), underwent attempted balloon valvuloplasty in this institution. The procedure was accomplished in 28 patients, but failed in six. Surgical pulmonary valvotomy was performed in the six patients with one mortality. Immediately following valvuloplasty, the mean right ventricular systolic pressure decreased from 109.2+/-28.6 to 55.1+/-23.6 mm Hg in the 28 patients (P<0.01). The mean pressure gradient decreased from 85.6+/-29.4 to 26+/-21.4 mm Hg (P<0.01). However, one who had a severely hypoplastic right ventricle requiring prolonged prostaglandin E1 infusion after valvuloplasty underwent a right ventricular outflow tract patch. After a follow-up period ranging from 2 months to 6.4 years (30.5+/-19.1 months), one patient developed recurrent pulmonary stenosis and underwent a repeated balloon valvuloplasty. Of the 27 patients (79%) with a definitive success of balloon valvuloplasty, the mean pressure gradient estimated with Doppler echocardiography at most recent follow-up was 15.2+/-6.8 mm Hg. Therefore, balloon valvuloplasty is the procedure-of-choice for critical pulmonary stenosis. Surgery should be reserved for those with unsuccessful balloon valvuloplasty.

Early detection of unilateral occlusion of duplicated uterus with ipsilateral renal anomaly in young girls: two case reports with three-dimensional sonography

Early detection of unilateral occlusion of duplicated uterus with ipsilateral renal anomaly is very rare and difficult. We present two cases using three-dimensional (3D) sonography as a noninvasive, comprehensive and effective method in the early detection of this syndrome in the young girls. The two young, unmarried girls had irregular abdominal discomfort and pain during the recent few years. Series traditional study showed pelvic lesions, but failed to recognized the definite cause. With 3D sonography, we demonstrated the rare congenital anatomic relationships and gave the optimal management. The girls recovered soon and had uneventful OPD follow-up. Application of 3D sonography in the suspected young girls avoids unnecessary examinations and invasive interventions, decreases the morbidity and improves their quality of life.

Electrophysiological profile after inward rectifier K channel blockade by barium in isolated rabbit hearts. Altered repolarization and unmasked decremental conduction property

AIMS

The aims of this study were to define the changes of cardiac conduction properties after selective IK1 blockade in isolated hearts.

METHODS AND RESULTS

Intracardiac recording and stimulation in Langendorff-perfused rabbit hearts were used to define cardiac conduction properties after Ba2+, a well known IK1 blocker. Ba2+ prolonged the corrected QT interval and decreased, or even abolished, the amplitude of the T wave. The conduction time through the sinoatrial (SA interval), the atrioventricular node (AH interval) and His-Purkinje system (HV interval) were not significantly changed. However, at higher atrial pacing rates the HV interval was lengthened by Ba2+ in a frequency-dependent manner. The recovery curve of the His-Purkinje system (the relationship of H2V2 to V1H2) was changed by Ba2+ to a prematurity-dependent pattern (AV nodal behaviour). Such a response was neither observed with 4-aminopyridine (Ito blocker) nor with d-sotalol (IK blocker). The atrial and ventricular refractory periods as well as the relative refractoriness (measured by the difference between relative refractory period and the absolute refractory period) of the ventricular tissue were increased by Ba2+.

CONCLUSION

The electrophysiological profile of selective IK1 block in isolated hearts revealed altered repolarization of cardiac tissue. The decremental conduction properties, which are normally present in the atrioventricular node (with a paucity of IK1), were unmasked by IK1 block in the His-Purkinje system. The T wave, particularly its amplitude, is more closely related to IK1 than to Ito.

Tricuspid atresia with persistent truncus arteriosus

The association of tricuspid atresia and persistent truncus arteriosus is a very rare congenital anomaly. We report a newborn with a prenatal diagnosis of tricuspid atresia, in whom associated type II persistent truncus arteriosus was found by postnatal echocardiography. The patient had mild cyanosis and developed heart failure soon after birth. Balloon septostomy was performed to enlarge the interatrial communication. However, her condition rapidly deteriorated and she died of sepsis and heart failure at the age of 14 days.

Acute poisoning with a herbicide containing imazapyr (Arsenal): a report of six cases

BACKGROUND

Acute pesticide poisoning is a major cause of morbidity and mortality in Taiwan and herbicides are most frequently implicated. Imazapyr [2-(4-isopropyl-4-methyl-5-oxo-2 imidazoline-2-yl)nicotinic acid] is a new herbicide, recently registered in Taiwan under the tradename "Arsenal" (Imazapyr 23.1%, Cyanamid Taiwan Corporation, Taipei). Imazapyr is also marketed as Assault, Chopper, Contain, and Pivot. To the best of our knowledge, there is no information in the literature concerning acute toxicity in humans after ingestion of herbicides containing this compound.

METHOD

Six cases of acute poisoning with Arsenal occurred during the period 1993-1997 in a single hospital. Emergency room records and medical charts were reviewed.

RESULTS

Of 6 cases, 5 were suicide attempts and 1 was an act of violence inflicted on a child. Three of the 6 patients (50%) presented with severe symptoms, including impairment of consciousness and respiratory distress requiring intubation. Other presentations included metabolic acidosis (2), hypotension (2), leukocytosis (3), fever (2), mild elevation of hepatic transaminase and creatinine (2), unconjugated hyperbilirubinemia (2), oral ulceration (2), pharyngolaryngitis (2), and chemical burns of the cornea (1). All cases had copious vomiting after ingestion of Arsenal. No mortality occurred.

CONCLUSION

According to our observations, it appeared the toxic syndrome that results from a large quantity (> 100 mL) of Arsenal herbicide ingestion consists of hypotension, pulmonary dysfunction, oral mucosal and gastrointestinal irritation, and transient liver and renal dysfunction. However, the existence of a dose-response relationship, with increasing amounts of ingestion resulting in more severe symptoms, needs further observation and studies that include a larger series.

The significance of early subtle coronary arterial lesions on echocardiogram in Kawasaki disease

Intensive echocardiographic studies were undertaken in 37 patients with Kawasaki disease (KD) and 12 febrile controls during the acute stages. Video-tape recordings were read doubly-blinded by 3 pediatric cardiologists at 2 hospitals. Three characteristics of subtle coronary arterial lesions, including contour of lumen, smoothness of endothelium and sono-homogeneity of the surrounding tissue were particularly described. Seven of the 37 KD patients (19%) were found to have coronary arterial aneurysms (CAA) at the end of the convalescent stage. The 3 cardiologists agreed in the diagnosis of the subtle lesions by 72%. More patients with Kawasaki disease were found to have an irregular endothelium than the controls (P < 0.001). KD patients later complicated with CAA were more likely to have had the three characteristics of subtle coronary lesions during the acute stage than the KD patients without aneurysms (P < 0.001). Also, the coronary arterial size measured during the acute stage were found to be positively correlated with their largest dilatation at the convalescent stage (P = 0.0001, r = 0.61). We conclude that early subtle coronary arterial lesions can herald the development of coronary arterial aneurysms.

Regression of ductus arteriosus aneurysm in a neonate demonstrated by three-dimensional computed tomography

We present a case of ductus arteriosus aneurysm in a neonate in whom the diagnosis was made by echocardiography, three-dimensional surface rendering computed tomography (CT) and was subsequently confirmed by angiography. Regression of aneurysm after indomethacin treatment was clearly demonstrated in a follow-up CT scan. To our knowledge, this is the first report of ductus arteriosus aneurysm and its regression detected by 3D surface rendering CT.

Differential pulmonary flow in hypoplastic left heart syndrome

We report a case of hypoplastic left heart syndrome associated with restrictive interatrial communication and partial anomalous pulmonary venous connection via a right lower pulmonary vein draining to the inferior vena cava. We found unequal pulmonary artery pressure and different pulmonary artery structure, with the right pulmonary artery being lower in pressure and more tortuous and dilated in its peripheral branches than the left. This was attributed to the variant degrees of pulmonary venous obstruction. The left pulmonary venous return was severely obstructed by the restrictive interatrial communication, whereas the anomalous right lower pulmonary vein drained into the inferior vena cava, with less obstruction. To the best of our knowledge, there has never before been a report of differential pulmonary flow associated with a partial anomalous pulmonary vein, in a case of hypoplastic left heart syndrome.

Genetic tracing of arterial graft flow surface endothelialization in allogeneic marrow transplanted dogs

In order to trace genetically the source of fallout endothelialization on arterial grafts, six beagle dogs with successful autologous bone marrow transplantation received composite tandem aortic grafts with an isolated, totally impervious Dacron graft and a porous Dacron graft for 12 weeks. For impervious segments, five of 12 fresh tissue samples were Factor VIII/von Willebrand factor + (FVIII/vWF) and seven had faint or negative signals; three of the FVIII/vWF + samples had alpha-actin + smooth muscle cells. Polymerase chain reaction (PCR) study showed eight had a pure donor DNA genotype and four had donor/host mixed, with the donor predominant. Of 12 AgNO3-stained samples, 11 showed pure donor type and one had donor/host mixed, with the donor predominant. For porous segments, all 12 fresh samples had positive flow surface FVIII/vWF and alpha-actin cells. PCR showed all these samples and all 12 AgNO3-stained samples had donor/host mixed type, but the host pattern was predominant. Porous graft healing appears to involve both cellular fallout and tissue ingrowth, and bone-marrow-derived cells may be a source for fallout.

Lack of evidence for a polymorphism at codon 160 of human O6-alkylguanine-DNA alkyltransferase gene in normal tissue and cancer

O6-benzylguanine (BG) is a potent, specific inactivator of the DNA repair protein O6-alkylguanine-DNA alkyltransferase (AGT), which enhances sensitivity to nitrosoureas in cells and tumor-bearing animals. BG is presently undergoing clinical trials for development as an agent to enhance the therapeutic index of alkylating agent chemotherapy. It has been reported that a polymorphism exists in the human agt gene, with about 15% of the Japanese population having arginine at codon 160 instead of glycine on the polypeptide (Y. Imai et al., Carcinogenesis, 16: 2441-2445, 1995). The resultant mutant AGT protein is equally effective against both methylated DNA as compared with wild type protein. However, this mutant AGT protein was less sensitive to inactivation by BG with a 20-fold increase in the ED50 value. This observation raised the possibility that a subpopulation of patients may be resistant to BG due to a single base change. We have demonstrated that this alteration also reduces the sensitivity to O6-benzyl-8-oxoguanine, an equally potent, yet much longer-lived human metabolite of BG. To test the possibility that this germ-line mutation of the agt gene might explain resistance to BG and O6-benzyl-8-oxoguanine of patients on our Phase I clinical trials, we evaluated the DNA from lymphocytes of 18 patients. The G160R mutation was not found in any of the 18 patients. To determine the frequency of this mutation in the United States population, DNA from 181 healthy individuals were investigated and, again, the mutation was not observed in this cohort. Therefore, if the mutation exists, it is in statistically <1.6% of the United States noncancerous population. To investigate the possibility that this mutation might be somatic, we evaluated genomic DNA samples from 94 human primary cancers of four different histological subtypes (brain, colon, esophageal, and head and neck). Again, none were found to have the G160R mutation.

The expression of soluble intercellular adhesion molecule-1 in endometriosis

OBJECTIVE

To investigate the association between concentrations of soluble intercellular adhesion molecule-1 (ICAM-1) and interferon-gamma (IFN-gamma) with regard to the severity of endometriosis.

DESIGN

Cross-sectional study.

SETTING

Infertility unit in a university hospital.

PATIENT(S)

Seventy-one infertile patients who underwent laparoscopic evaluation were divided into two groups: 36 patients with endometriosis served as cases, and 35 patients without endometriosis served as control subjects.

INTERVENTION(S)

Peripheral blood and peritoneal fluid (PF) were collected from these patients during laparoscopic examination.

MAIN OUTCOME MEASURE(S)

Quantitative determination of levels of human ICAM-1 and IFN-gamma was performed with the use of an ELISA. The data were evaluated by Student's t-test, analysis of variance, and regression analysis.

RESULT(S)

Significantly elevated levels of soluble ICAM-1 were found in the sera of patients with endometriosis, especially those with advanced stages of the disease. Decreased IFN-gamma levels, which were negatively correlated with serum levels of soluble ICAM-1, also were noted in the PF of patients with endometriosis.

CONCLUSION(S)

The increased serum levels of ICAM-1 found in patients with endometriosis may indicate the presence of an active disease process. Further, the increased levels of soluble ICAM-1 in peripheral blood were inversely correlated with the concentrations of IFN-gamma in PF. The increased levels of soluble ICAM-1 in plasma may be associated with an immunologic feedback response that blocks further infiltration of immune cells. These findings may be of value in the diagnosis and evaluation of endometriosis.

Transarterial approach of the pulmonary artery in anatomically corrected malposition of the great arteries by manipulating a catheter inverted with balloon floating maneuver

We describe two neonates with anatomically corrected malposition of the great arteries (ACM). A 1-day-old female newborn, who had the salient clinical findings of Goldenhar syndrome, behaved like a patient with the tetralogy of Fallot. The cardiac malformations included ACM, perimembranous inlet and outlet ventricular septal defect with tricuspid valve straddling, conoventricular septal malaligement, bilateral cori without aortic-mitral continuity, pulmonary stenosis at subvalvular, valvular, and supravalvular levels, and bicuspid semilunar valves. After the procedure of left Blalock-Taussig shunt at 3 months of age, cyanosis was alleviated. The other 1-month-old male newborn, who presented with prolonged feeding, tachypnea and tachycardia, likened to a patient with the hypoplastic left heart syndrome. He had a combination of ACM, mitral stenosis, hypoplastic left atrium and left ventricle, a restrictive patent foramen ovale, ventricular septal defect, subaortic conus without aortic-mitral continuity, subaortic stenosis, and a narrow ascending aortic root. Rashkind balloon atrioseptostomy was done with limited success. He survived a Norwood procedure. Transarterial entry of the catheter, which was inverted with the aid of balloon floating maneuver, to hook the retro-aortic pulmonary artery in ACM is recommended.

Giant intraluminal fibrovascular polyp of the esophagus

Giant polyps of the esophagus are relatively rare. Without previous history, the diagnosis of the disease is difficult to be made by esophagography and esophagoscopy. A case of giant intraluminal fibrovascular polyp (13x4x3.5 cm) of the esophagus is presented. The polyp was retrieved from the esophagus by a Foley's catheter and resected via the oral route.

Blood supply of esophageal stumps

BACKGROUND/AIMS

The purpose of the study was to determine the blood supply of stumps of mobilized esophagus.

METHODOLOGY

Esophageal stumps of five groups of rabbits were studied. The esophageal stumps were dyed via intravenous injection of trypan blue, and were analyzed by color image processing.

RESULTS

The dyed length of the esophageal stump was 7.15+/-0.5 cm in the stomach-connecting group; 4.6+/-0.69 cm in the stomach-connecting with myotomy group; 6.1+/-0.88 cm in the distal stomach-connecting group; 3.0+/-0.47 cm in the neck-connecting group; and, 2.1+/-0.2 cm in the neck-connecting with myotomy group. There was a significant difference in the dyed length between the stomach-connecting and neck-connecting groups (p=0.000), and between the stomach-connecting and stomach-connecting with myotomy groups (p=0.026), but there was no significant difference between the neck-connecting and neck-connecting with myotomy (p=0.094), or the stomach-connecting and distal stomach-connecting groups (p=0.053).

CONCLUSIONS

Stumps of the mobilized esophagus in rabbits, with or without myotomy, exhibit differences in dyed length, depending on the diameter, wall thickness and location of the blood supply in the esophagus.

Electrophysiological mechanisms for the antiarrhythmic activities of naloxone on cardiac tissues

It has been reported that naloxone, an opioid antagonist, has antiarrhythmic activity in vivo. In Langendorff perfused rat hearts, we found that ischemia-reperfusion-induced ventricular tachyarrhythmia reverted to normal sinus rhythm after the treatment with naloxone (3 approximately 10 microM). The method of voltage and current clamp were used to study the underlying mechanism of its antiarrhythmic activity on isolated cardiac myocytes. In isolated rat ventricular and in guinea-pig and human atrial myocytes, naloxone prolonged the action potential duration reversibly. In rat ventricular myocytes, naloxone (1 approximately 30 microM) inhibited sodium current (I(Na)), transient outward potassium current (I(to)), and calcium current (I(Ca)). On the contrary, the addition of naloxone significantly increased inward rectifier potassium current (I(K1)). For the effect on I(Na), naloxone did not shift the inactivation curve of I(Na) but retarded the I(Na) recovery rate from inactivation state. Naloxone suppressed I(to) with a significant left-shift of the inactivation curve, however, the time course of I(to) recovery from inactivation was not affected. In guinea pig atrial myocytes, naloxone (10 microM) decreased the delayed rectifier K+ current (IK). These results show that naloxone exert various extent of inhibition on I(Na), I(to), IK and I(Ca). The prolongation of cardiac action potential is related to the inhibition of I(to) and IK. The antiarrhythmic activity of naloxone is more closely related to the inhibition of Na+ and K+ currents rather than the blockade of myocardial opioid receptors.

Supraventricular tachycardia in patients with right atrial isomerism

OBJECTIVES

To clarify the prevalence and mechanism of supraventricular tachycardia in patients with right atrial isomerism.

BACKGROUND

Paired SA and dual atrioventricular (AV) nodes have been described in patients with right atrial isomerism. However, the clinical significance remains unclear.

METHODS

From 1987 to 1996, a total of 101 patients (61 male, 40 female) and four fetuses were identified with right atrial isomerism. The diagnosis of supraventricular tachycardia exclude the tachycardia with prolonged QRS duration or AV dissociation, and primary atrial tachycardia.

RESULTS

The median follow-up duration was 38 months (range 0.2-270 months). Supraventricular tachycardia was documented in 25 patients (24.8%) and one fetus (25%) (onset age ranged from prenatal to 14 years old; median 4 years old). Actuarial Kaplan-Meier analysis revealed that the probability of being free from tachycardia was 67% and 50% at 6 and 10 years of age, respectively. These tachycardias could be converted by vagal maneuvers in one, verapamil in seven, propranolol in four, digoxin in two, procainamide in one, and rapid pacing in five. Spontaneous conversion was noted in six (including the fetus). Seven cases had received electrophysiological studies. Reciprocating AV tachycardia could be induced in five and echo beats in one. The tachycardia in three patients was documented as incorporating a posterior AV node (antegrade) and an anterior or a lateral AV node (retrograde). Two of them received radiofrequency ablation. Successful ablation in both was obtained by delivering energy during tachycardia, aimed at the earliest retrograde atrial activity and accompanied by junctional ectopic rhythm. The patient with echo beats developed tachycardia soon after operation.

CONCLUSIONS

Supraventricular tachycardia is common in patients with right atrial isomerism and can occur during the prenatal stage. Drugs to slow conduction through the AV node may help to terminate the tachycardia. Radiofrequency ablation is a safe and effective treatment alternative to eliminate tachycardia.