Biomedical subjects
Publications and source records attributed to Betau Hwang.
A retropharyngeal abscess is a rare presentation of Kawasaki disease. Herein, we present a case of Kawasaki disease mimicking a retropharyngeal abscess, and review five previously published case reports. Once the correct diagnosis of Kawasaki disease is established, any abscess-like lesion on computed tomography may be just a false-positive finding.
BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia in adulthood. Although selective ablation of the slow AV nodal pathway can cure AVNRT, accidental AV block may occur. The details on the electrophysiologic characteristics, quantitative data on the voltage inside Koch's triangle, and the use of three-dimensional noncontact mapping to facilitate the catheter ablation of AVNRT associated with a high-risk for AV block or other arrhythmias have been limited. METHODS AND RESULTS: Nine patients (M/F=5/4, 34+/-23 years, range 17-76) with clinically documented AVNRT were included. All patients had undergone previous sessions for slow AV nodal pathway ablation but they had failed, because of repetitive episodes of complete AV block during the RF energy applications. Further, one patient had a complex anatomy and 4 patients were associated with other tachycardias, respectively. The electrophysiologic studies revealed that 4 patients had the slow-fast, 4 the slow-intermediate and one the fast-intermediate form of AVNRT. Noncontact mapping demonstrated two types of antegrade AV nodal conduction, markedly differing sites of the earliest atrial activation during retrograde VA conduction, and a lower range of voltage within Koch's triangle. The lowest border of the retrograde conduction region was defined on the map, and the application of the RF energy was delivered below that border to prevent the occurrence of AV block. The distance between the successful ablation lesions and the lowest border of the retrograde conduction region was significantly shorter in the patients with the slow-intermediate form of AVNRT than in those with the slow-fast form (5.5+/-3.4 vs. 15+/-7.6 mm; p<0.05). After the ablation procedure, either rapid pacing or extrastimulation could not induce any tachycardia, and there was no recurrence during the follow-up (10.3+/-5.4, 2 to 22 months). CONCLUSIONS: Noncontact mapping could effectively demonstrate the antegrade and retrograde atrionodal conduction patterns, electrophysiologic characteristics of Koch's triangle, and guide the successful catheter ablation in difficult AVNRT cases.
The SCN5A mutations have been associated with a variety of arrhythmic disorders, including type 3 long QT syndrome (LQT3), Brugada syndrome and inherited cardiac conduction defects. The relationship between genotype and phenotype in SCN5A mutations is complex. Some SCN5A mutations may cause death or severe manifestations in some people and may not cause any symptoms or arrhythmias in others. The causes of these unpredictable clinical manifestations remain incompletely understood. The molecular basis of a four-generation family with cardiac conduction abnormalities was studied and whether variants in the SCN5A gene could account for the cardiac phenotypic variability observed in this family was determined. A novel mutation (W1421X) of SCN5A was identified in a four-generation family with cardiac conduction abnormalities and several cases of sudden death. Most family members who carry this W1421X mutation have developed major clinical manifestations or electrocardiographic abnormalities, both of which became more prominent as the patients grew older. However, the 73-year-old grandfather, who carried both the W1421X and R1193Q mutations, had thus far remained healthy and presented with only subtle electrocardiographic abnormalities, whereas most of his offspring, who carried a single mutation (W1421X), had died early or had major disease manifestations. This observation suggests that the R1193Q mutation has a complementary role in alleviating the deleterious effects conferred by W1421X in the function of the SCN5A gene. This report provides a good model to explain the mechanism of penetrance of genetic disorders.
BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) can be usually induced by atrial pacing or extrastimulation. However, it is less commonly induced only by ventricular pacing or extrastimulation. OBJECTIVE: The purpose of this retrospective study was to investigate the electrophysiologic characteristics in patients with slow-fast form AVNRT that could be induced only by ventricular pacing or extrastimulation. METHODS: The total population was 1497 patients associated with AVNRT. There were 1373 (91.7%) patients who had slow-fast form AVNRT included in our study. Group 1 (n = 45) could be induced only by ventricular pacing or extrastimulation, and Group 2 (n = 1328) could be induced by only atrial stimulation or both atrial and ventricular stimulation. The electrophysiologic characteristics of the group 1 and group 2 patients were compared. RESULTS: Group 1 patients had a significantly lower incidence of both antegrade and retrograde dual AV nodal pathways. The pacing cycle length (CL) of the antegrade 1:1 fast pathway (FP) and antegrade ERP of the FP were both significantly shorter in Group 1 patients. Mean antegrade FRP of the fast and slow pathways were significantly shorter in Group 1 patients. The differences of pacing CL of 1:1 antegrade conduction, antegrade ERP and FRP were much longer in Group 2 patients. CONCLUSION: This study demonstrated the patients with slow-fast form AVNRT that could be induced only by ventricular stimulation had a lower incidence of dual AV nodal pathways and the different electrophysiologic characteristics (shorter pacing CL of the antegrade 1:1 FP, antegrade ERP of the FP and the differences of pacing CL of 1:1 antegrade conduction, antegrade ERP and FRP) from the other patients. The specific electrophysiologic characteristics in such patients could be the reason that could be induced only by ventricular stimulation.
Our previous study demonstrated that norepinephrine (NE) induces endothelial apoptosis mainly through down-regulation of Bcl-2 protein and activation of the beta-adrenergic and caspase-2 pathways. However, whether reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPKs) are involved in this signal transduction remains unknown. Endothelial cells cultured from neonatal rat heart were treated with 100 microM NE. Proteins of MAPKs and Bcl-2 family were assayed by Western blotting. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated nick end-labeling assay. ROS was analyzed with flow cytometry. Caspase activity was measured using specific fluorogenic substrates. Treatment with NE increased intracellular ROS level and extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 phosphorylation. Whereas the phosphorylated form of Akt was decreased. The NE-induced apoptosis was abrogated by SP600125 (a specific inhibitor of JNK). Antioxidants such as vitamin C and N-acetyl cysteine inhibited NE-induced ROS production, JNK phosphorylation, caspase activation and apoptosis. Exogenously added superoxide dismutase or catalase markedly diminished NE-induced ROS production and cell death. In conclusions, our study is the first report documenting that NE induces apoptosis in neonatal rat endothelial cells via a ROS-dependent JNK activation pathway. Antioxidants may be useful in the prevention and management of NE-mediated endothelial apoptosis during heart failure.
BACKGROUND: Atrioventricular nodal reentry tachycardia (AVNRT) is based on the concept of dual AV node pathways that are functionally and anatomically distinct. The bigger coronary sinus ostium (CSO) in patients with AVNRT compared to other supraventricular tachycardias (SVTs) may produce separation of atrial inputs into the AV node or create anisotropic conduction, thus giving rise to a different AV nodal physiology. Previous studies measuring the size of the CSO using CS angiography between patients with AVNRT and other SVTs showed conflicting results. Besides, no previous studies have compared the CS morphology of the different forms of AVNRT. OBJECTIVES: This study compares the size and morphology of the CS among patients with typical AVNRT, atypical AVNRT and accessory pathways mediated reentrant tachycardia (AVRT). METHODS: Ninety-six patients with clinically documented SVTs were divided into three groups. The diameter of the CS was measured in LAO projection during end ventricular systole (by choosing the last ventricular inward motion). The CSO as well as 5, 10 and 15 mm inside the CS were measured. CS morphology is defined as either wind-sock shape or tubular shape. RESULTS: The size of the CS ostium was 13.58 +/- 3.98, 15.93 +/- 4.86 and 12.50 +/- 2.83 mm for the atypical AVNRT, typical AVNRT and AVRT, respectively (p = 0.03). There was significant difference in the size of the CS from the ostium until 15 mm into the CS between 1) typical AVNRT and AVRT, 2) typical AVNRT and atypical AVNRT. Typical and atypical AVNRT patients had more windsock morphology CS (13/32, 40.6% and 10/32, 31.2%) compared to AVRT which had only one (1/32, 3.1%) windsock morphology (p = 0.002). CONCLUSION: The easier CS cannulation in patients with typical AVNRT could be due to a bigger CS size and to a more windsock morphology. The CS size and morphology may be a very important substrate of tachycardia in patients with AVNRT.
Central nervous system (CNS) involvement is not rare in extraocular retinoblastoma, and it is not surprising to find it in view of its route of spread. However, although spinal recurrence presenting as spinal cord compression (SCC) is a form of CNS involvement, it is extremely rare. This report describes two patients with unilateral retinoblastoma with spinal recurrence presenting as SCC. The first patient developed erythematous swelling of the right foot and weakness of the bilateral lower limbs at 7 months after left enucleation. Examination revealed pitting edema of bilateral feet and muscle power of 2+ to 3+, with intact sensory function. The second patient developed weakness of the bilateral lower limbs, and defecative and urinary difficulty for 2 days at 8 months after left enucleation. Examination revealed pitting edema of bilateral feet and muscle power of 2+, with defective sensory function. Both patients received surgery and local irradiation after SCC. The first patient refused chemotherapy and survived only 4 months due to disease progression. The second patient received systemic and intrathecal chemotherapy, and survived 19.5 months without disease progression. Spinal recurrence with SCC should be suspected when leg weakness or bowel or bladder disturbance occurs in patients with retinoblastoma.
Herein, we report on the correct diagnosis and effective treatment procedures for pyomyositis, a very rare complication that remains a diagnostic challenge in children being treated for acute lymphoblastic leukemia (ALL). We report the case of a 10-year-old girl suffering from pyomyositis with ALL. Correct diagnosis is usually delayed because the initial symptom of pyomyositis, usually local pain, is similar to the common side effect of vincristine, a drug necessary for ALL induction therapy. We summarize the procedures taken to reach a timely diagnosis and therapeutic success.
BACKGROUND: Esophageal atresia (EA), tracheoesophageal fistula (TEF), or both is a complicated problem. The purpose of this study was to evaluate the outcomes and postoperative complications in patients with EA/TEF who were admitted to our hospital. METHODS: In total, 15 patients were enrolled from 1994 to 2003, including 8 males and 7 females. Patient demographics, associated anomalies, and outcomes were analyzed. RESULTS: The most common variant was EA with a distal TEF (type C), which occurred in 12 patients (80%). The latter had associated congenital anomalies, and cardiac anomalies were the most frequent, occurring in 8 patients (53.3%). Of the 6 cases who had life-threatening anomalies, 4 (66.7%) died, and of the 9 cases who had no life-threatening-anomalies, 2 (22.2%) died. Tracheomalacia and/or stenosis were diagnosed in 8 patients (66.7%) postoperatively. Though 3 of the 4 cases who suffered from dying spell received intratracheal stent implantation, 2 cases still died. CONCLUSION: The survival rate of the patients with EA/TEF is influenced mainly by associated life-threatening anomalies. TMS combined with a history of dying spell may be the major fatal complication.
The incidence of multifocal atrial tachycardia (MAT) is very low and accounts for less than 1% of supraventricular tachycardia in infants and children. In this report, the clinical characteristics, medical treatment and outcome of MAT in 2 children are described. The first patient presented with tachycardia and respiratory failure since the day after birth. First, he received amiodarone, propranolol, and digoxin and then amiodarone alone. The heart rhythm converted to sinus rhythm 2 weeks after hospitalization. Although nonsustained MAT was occasionally observed when the infant suffered from pulmonary infection, the frequency of recurrent MAT decreased as the infant grew up. The second patient was a 5-year-old girl. She had congenital heart disease with double outlets of right ventricle (DORV), patent ductus arteriosus, coarctation of aorta, and ventricular and atrial septal defects. She underwent total correction at the age of 4 years. MAT was noted 3 months after the operation with the presentation of congestive heart failure. The heart rate slowed down and returned to normal sinus rhythm within several hours after amiodarone use. The symptoms and signs of congestive heart failure also disappeared. The patient took amiodarone regularly, and no tachycardia was detected during the follow-up period. MAT is considered to be a relatively benign arrhythmia with likely good outcome if there is no severe underlying illness. It can be well controlled under appropriate drugs, and a long period of follow-up is suggested. If pharmacologic intervention is required, we suggest that amiodarone may be an excellent choice.
Epidermolysis bullosa (EB) encompasses a heterogeneous group of genodermatoses, characterized by fragility and blistering of the skin, often associated with extracutaneous manifestations. The level of vesiculation within the skin defines 3 major subtypes of EB: EB simplex, junctional EB, and dystrophic EB. We present the case of a male neonate of 36 weeks of gestation, who was born with a few blisters with erosions and who rapidly developed extensive blistering of the skin. Histopathology revealed subepidermal blistering. Electron microscopy confirmed the cleavage of epidermis from dermis within the lamina lucida. Junctional EB was the diagnosis. The patient was discharged after hospitalization for 28 days. The development of new blisters with erosions were gradually improved after AQUACEL Ag dressing, and the general condition was much better than at admission. The patient likely has a subtype of junctional EB termed generalized atrophic benign EB that clinically improves with age. He has the potential to father children and has a normal life expectancy.
OBJECTIVE: To investigate the therapeutic effects of bronchoalveolar lavage (BAL) with either diluted surfactant (SBAL) or perfluorochemical liquid (PBAL), followed by either conventional mechanical ventilation (CMV) or partial liquid ventilation (PLV), on lung injury and proinflammatory cytokine production induced by meconium aspiration in newborn piglets. DESIGN: A prospective, randomized, experimental study. SETTING: An animal research laboratory at a medical center. SUBJECTS: Anesthetized and mechanically ventilated newborn piglets (n = 27). INTERVENTIONS: The animals were instilled with 3-5 mL/kg 25% human meconium via an endotracheal tube to induce meconium aspiration syndrome (MAS). After stabilization, animals were randomly assigned to either CMV group (no BAL) or one of the treatment groups (SBAL-CMV, SBAL-PLV, PBAL-CMV, and PBAL-PLV). MEASUREMENTS AND MAIN RESULTS: Cardiopulmonary variables were monitored, and interleukin-1beta and interleukin-6 content of the serum and lung tissue was measured. The animals without any treatment (CMV group) displayed the worst outcome; the animals in the PBAL-PLV group had the best gas exchange, lung compliance, and least pulmonary damage; and the SBAL-CMV, PBAL-CMV, and SBAL-PLV groups had intermediate effects. The serum interleukin-1beta concentration of the CMV group was significantly higher than all other groups over time (p < .05), and interleukin-6 concentration was significantly higher than the PBAL-PLV group (p < .05). The tissue interleukin-1beta and interleukin-6 contents were also highest in the CMV group and lowest in the PBAL-PLV group. CONCLUSIONS: Initial therapeutic BAL and therapeutic BAL followed by PLV with the same perfluorochemical liquid provided significant therapeutic effects in treating an animal model with severe MAS and therefore warrant consideration in cases that are intractable to other therapies.
BACKGROUND: Kawasaki disease is the leading cause of acquired heart disease in childhood. However, there are only a few reports in infants younger than 6 months. The objective of this study is to investigate the clinical and laboratory characteristics of Kawasaki disease in infants younger than 6 months. METHODS: From 1994 to 2003, 120 patients with Kawasaki disease diagnosed at our institution were included. Group 1 consisted of 20 (17%) patients younger than 6 months, and group 2 consisted of 100 (83%) patients older than 6 months. Clinical manifestations, laboratory results, echocardiographic findings, treatment and outcome were compared between these 2 groups. RESULTS: Clinical manifestations (hydrops of gallbladder: 0% versus 16%, P < 0.001) and laboratory results (white blood cell count 21,740 +/- 11,706 versus 11,830 +/- 4390/mm3, P < 0.001; hemoglobin 9.98 +/- 1.25 versus 10.8 +/- 1.37 g/dL, P = 0.015; platelet 483 +/- 393 versus 355 +/- 138 x 1000/mm3, P = 0.011; triglyceride 138 +/- 77.5 versus 107 +/- 17 mg/dL, P < 0.001) were different between patients with Kawasaki disease younger and older than 6 months, respectively. Younger infants were more likely to have incomplete presentation (35% versus 12%, P = 0.025), coronary involvement (65% versus 19%, P < 0.001), late intravenous immunoglobulin treatment and relatively poor outcome. CONCLUSIONS: Infants younger than 6 months with prolonged unexplained febrile illnesses should be suspected as having Kawasaki disease, despite the incomplete clinical presentation. Because early diagnosis and timely treatment are difficult in younger infants with Kawasaki disease because of delayed and incomplete clinical presentations, echocardiogram becomes an important implement for diagnosis. Early intravenous immunoglobulin treatment is required in view of the highest risk of coronary involvement in them.
BACKGROUND: The physical-chemical properties of perfluorochemical (PFC) liquids have been shown to influence physiological and cellular responses during partial liquid ventilation (PLV). The aim of this study is to compare the relationship between patho-physiological endpoints and the physical properties of three PFC liquids used in treating acute lung injury. METHODS: A total of 18 juvenile rabbits were randomized into conventional mechanical ventilation or PLV groups after lung saline lavages. Three PFC liquids, including Flutec perfluoro-1,3,5-trimethylcyclohexane (PP4; vapor pressure, 28.8 mmHg at 37 degrees C), Perfluorodecalin (PFD; vapor pressure, 13.6 mmHg at 37 degrees C), and Perflubron (PFB; vapor pressure, 10.4 mmHg at 37 degrees C) were used for PLV with no replacement for 4 h. A thermal detector was used to measure PFC loss rate. Physiological measurements and evaporative loss rate of PFC were done every 30 min, and lung histology was examined. RESULTS: The mean evaporative loss rate was significantly higher in the PP4 group (4.75 +/- 0.24 mL/kg per h) than in either the PFD (1.43 +/- 0.11 mL/kg per h) or the PFB (1.18 +/- 0.05 mL/kg per h) group (P < 0.05). The oxygenation of PFD and PFB was maintained good for 4 h, however, the PP4 group showed a fast deterioration since 2 h post-treatment due to fast dropping of the residual PP4 amount in lungs. Histology showed good alveolar integrity in the PFD and PFB groups. CONCLUSIONS: The effects of PLV are directly influenced by the evaporative property of the PFC liquid. With no replacement over 4 h, PLV effects could be maintained with utilizing a PFC liquid with low, rather than high, vapor pressure. PFC with high vapor pressure has a high loss rate and low residual volume that causes poor maintenance on oxygenation during PLV. Therefore, measuring PFC loss rate is important in future studies and clinical application of PLV.
BACKGROUND: The majority of cardiac arrhythmias in children are supraventricular tachycardia, which is mainly related to an accessory pathway (AP)-mediated reentry mechanism. The investigation for Wolff-Parkinson-White (WPW) syndrome in adults is numerous, but there is only limited information for children. This study was designed to evaluate the specific electrophysiologic characteristics and the outcome of radiofrequency (RF) catheter ablation in children with WPW syndrome. METHODS: From December 1989 to August 2005, a total of 142 children and 1,219 adults with atrioventricular reentrant tachycardia (AVRT) who underwent ablation at our institution were included. We compared the clinical and electrophysiologic characteristics between children and adults with WPW syndrome. RESULTS: The incidence of intermittent WPW syndrome was higher in children (7% vs 3%, P=0.025). There was a higher occurrence of rapid atrial pacing needed to induce tachycardia in children (67% vs 53%, P=0.02). However, atrial fibrillation (AF) occurred more commonly in adult patients (28% vs 16%, P=0.003). The pediatric patients had a higher incidence of multiple pathways (5% vs 1%, P<0.001). Both the onset and duration of symptoms were significantly shorter in the pediatric patients. The antegrade 1:1 AP conduction pacing cycle length (CL) and antegrade AP effective refractory period (ERP) in children were much shorter than those in adults with manifest WPW syndrome. Furthermore, the retrograde 1:1 AP conduction pacing CL and retrograde AP ERP in children were also shorter than those in adults. The antegrade 1:1 atrioventricular (AV) node conduction pacing CL, AV nodal ERP, and the CL of the tachycardia were all shorter in the pediatric patients. CONCLUSION: This study demonstrated the difference in the electrophysiologic characteristics of APs and the AV node between pediatric and adult patients. RF catheter ablation was a safe and effective method to manage children with WPW syndrome.
BACKGROUND: Previous studies in adults have shown a significant shortening of the fast pathway effective refractory period (ERP) after successful slow pathway ablation. However, information on atrioventricular nodal reentrant tachycardia (AVNRT) in children is limited. The purpose of this retrospective study was to investigate the different effects of radiofrequency (RF) catheter ablation in pediatric AVNRT patients between those with and without dual atrioventricular (AV) nodal pathways. METHODS: From January 1992 to August 2004, a total 67 pediatric patients with AVNRT underwent an electrophysiologic study and RF catheter ablation at our institution. We compared the electrophysiologic characteristics between those obtained before and after ablation in the children with AVNRT with and without dual AV nodal pathways. RESULTS: Dual AV nodal pathways were found in 37 (55%) of 67 children, including 36 (54%) with antegrade and 10 (15%) with retrograde dual AV nodal pathways. The antegrade and retrograde fast pathway ERPs in children with dual AV nodal pathways were both longer than the antegrade and retrograde ERPs in children without dual AV nodal pathways (300 +/- 68 vs 264 +/- 58 ms, P = 0.004; 415 +/- 70 vs 250 +/- 45 ms, P < 0.001) before ablation. In children with antegrade dual AV nodal pathways, the antegrade fast pathway ERP decreased from 300 +/- 68 ms to 258 +/- 62 ms (P = 0.008). The retrograde fast pathway ERP also decreased after successful ablation in the children with retrograde dual AV nodal pathways (415 +/- 70 vs. 358 +/- 72 ms, P = 0.026). CONCLUSION: The dual AV nodal physiology could not be commonly demonstrated in pediatric patients with inducible AVNRT. After a successful slow pathway ablation, the fast pathway ERP shortened significantly in the children with dual AV nodal pathways.
BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) can usually be induced by atrial stimulation. However, it seldom may be induced with only ventricular stimulation, especially the fast-slow form of AVNRT. The purpose of this retrospective study was to investigate the specific electrophysiological characteristics in patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation. METHODS: The total population consisted of 1,497 patients associated with AVNRT, and 106 (8.4%) of them had the fast-slow form of AVNRT and 1,373 (91.7%) the slow-fast form of AVNRT. In patients with the fast-slow form of AVNRT, the AVNRT could be induced with only ventricular stimulation in 16 patients, Group 1; with only atrial stimulation or both atrial and ventricular stimulation in 90 patients, Group 2; and with only atrial stimulation in 13 patients, Group 3. We also divided these patients with slow-fast form AVNRT (n = 1,373) into two groups: those that could be induced only by ventricular stimulation (Group 4; n = 45, 3%) and those that could be induced by atrial stimulation only or by both atrial and ventricular stimulation (n = 1.328, 97%). RESULTS: Patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation had a lower incidence of an antegrade dual AVN physiology (0% vs 71.1% and 92%, P < 0.001), a lower incidence of multiple form AVNRT (31% vs 69% and 85%, P = 0.009), and a more significant retrograde functional refractory period (FRP) difference (99 +/- 102 vs 30 +/- 57 ms, P < 0.001) than those that could be induced with only atrial stimulation or both atrial and ventricular stimulation. The occurrence of tachycardia stimulated with only ventricular stimulation was more frequently demonstrated in patients with the fast-slow form of AVNRT than in those with the slow-fast form of AVNRT (15% vs 3%, P < 0.001). Patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation had a higher incidence of retrograde dual AVN physiology (75% vs 4%, P < 0.001), a longer pacing cycle length of retrograde 1:1 fast and slow pathway conduction (475 +/- 63 ms vs 366 +/- 64 ms, P < 0.001; 449 +/- 138 ms vs 370 +/- 85 ms, P = 0.009), a longer retrograde effective refractory period of the fast pathway (360 +/- 124 ms vs 285 +/- 62 ms, P = 0.003), and a longer retrograde FRP of the fast and slow pathway (428 +/- 85 ms vs 362 +/- 47 ms, P < 0.001 and 522 +/- 106 vs 456 +/- 97 ms, P = 0.026) than those with the slow-fast form of AVNRT that could be induced with only ventricular stimulation. CONCLUSION: This study demonstrated that patients with the fast-slow form of AVNRT that could be induced with only ventricular stimulation had a different incidence of the antegrade and retrograde dual AVN physiology and the specific electrophysiological characteristics. The mechanism of the AVNRT stimulated only with ventricular stimulation was supposed to be different in patients with the slow-fast and fast-slow forms of AVNRT.
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