Preserving normal ventricular activation versus atrioventricular delay optimization during pacing: the role of intrinsic atrioventricular conduction and pacing rate

The purpose of the study was to compare the effects of DDD pacing with optimal AV delay and AAI pacing on the systolic and diastolic performance at rest in patients with prolonged intrinsic AV conduction (first-degree AV block). We studied 17 patients (8 men, aged 69 +/- 9 years) with dual chamber pacemakers implanted for sick sinus syndrome in 15 patients and paroxysmal high degree AV block in 2 patients. Aortic flow and mitral flow were evaluated using Doppler echocardiography. Study protocol included the determination of the optimal AV delay in the DDD mode and comparison between AAI and DDD with optimal AV delay for pacing rate 70/min and 90/min. Stimulus-R interval during AAI (ARI) was 282 +/- 68 ms for rate 70/min and 330 +/- 98 ms for rate 90/min (P < 0.01). The optimal AV delay was 159 +/- 22 ms. AV delay optimization resulted in an increase of an aortic flow time velocity integral (AFTVI) of 16% +/- 9%. At rate 70/min the patients with ARI < or = 270 ms had higher AFTVI in AAI than in DDD (0.214 +/- 0.05 m vs 0.196 +/- 0.05 m, P < 0.01), while the patients with ARI > 270 ms demonstrated greater AFTVI under DDD compared to AAI (0.192 +/- 0.03 m vs 0.166 +/- 0.02 m, P < 0.01). At rate 90/min AFTVI was higher during DDD than AAI (0.183 +/- 0.03 m vs 0.162 +/- 0.03 m, P < 0.01). Mitral flow time velocity integral (MFTVI) at rate 70/min was higher in DDD than in AAI (0.189 +/- 0.05 m vs 0.173 +/- 0.05 m, P < 0.01), while at rate 90/min the difference was not significant in favor of DDD (0.149 +/- 0.05 m vs 0.158 +/- 0.04 m). The results suggest that in patients with first-degree AV block the relative impact of DDD and AAI pacing modes on the systolic performance depends on the intrinsic AV conduction time and on pacing rate.

Electrophysiological properties of the left atrium evaluated by coronary sinus pacing in patients with atrial fibrillation

Repetitive atrial firing (RAF), marked fragmentation of atrial activity (FAA), and interatrial conduction delay (CD) have been shown to be electrophysiological features of the atrium in patients with atrial fibrillation (AF). Moreover, it has been observed that atrial extrastimuli are more likely to induce AF when delivered from the right atrial appendage (RAA) than from the distal coronary sinus (CSd). We examined the electrophysiological properties of the atrial muscle by CS and RAA stimulation in patients with paroxysmal AF. Patients were divided into two groups: group I, consisting of 18 patients with clinical paroxysmal AF; and group II, consisting of 22 patients with various cardiac arrhythmias in which the substrate does not exist in the atrium. In group I, the following values of electrophysiological parameters of the atrium indicated that AF was more likely to be induced during RAA pacing than CSd pacing: atrial effective refractory period (RAA vs CSd: 201 +/- 28 ms vs 240 +/- 35 ms, P < 0.001), RAF zone (16 +/- 25 ms vs 0 +/- 0 ms, P < 0.03), FAA zone (38 +/- 37 ms vs 5 +/- 19 ms, P < 0.01), maximum interatrial conduction time (144 +/- 19 ms vs 93 +/- 19 ms, P < 0.0001) and CD zone (53 +/- 21 ms vs 9 +/- 18 ms, P < 0.0001). The values of the electrophysiological parameters of the atrium evaluated by CSd pacing in group I patients were not significantly different from those in group II patients. In conclusion, when coronary sinus stimulation is performed, electrophysiological properties of the atrium in patients with AF show a significant decrease in atrial vulnerability compared to stimulation from RAA and also show similar values to those in patients without AF. It might be suggested that the left posterior or posterolateral atrium is electrophysiologically stable even in patients with paroxysmal AF.

Clinical analysis of hypertrophic cardiomyopathy which evolved into dilated phase during long-term follow-up

The aim of the present study was to analyze the incidence, clinical features and prognosis of patients with hypertrophic cardiomyopathy (HCM) which evolved into dilated phase HCM. The medical records of 43 patients with HCM followed up for at least 10 years were analyzed retrospectively. The patients were divided into two groups: group A consisting of patients with dilated-phase HCM defined by a left ventricular end diastolic dimension (LVDD) of 55 mm or more and a left ventricular ejection fraction (LVEF) of less than 50% obtained by echocardiography, and group B, consisting of patients with HCM that did not evolve into dilated phase HCM. During the mean follow-up of 16.7 years, 10 patients (23.3%) evolved into dilated phase HCM (group A) while the remaining 33 patients (76.7%) did not (group B). Ventricular tachycardia (VT) occurred in 7 of the 10 patients (70.0%) in group A and in 5 of the 33 patients (15.2%) in group B (p < 0.001). An increase in LVDD and decreases in LVEF and SV1 + RV5 in the electrocardiogram were observed during the early phase of the follow-up period in group A, while these changes were gradual in group B. Cardiac death occurred in 5 (50.0%) of the 10 patients in group A and in 2 (6.1%) of the 33 patients in group B (p < 0.001). In conclusion, dilated-phase HCM is characterized by decreases in LVEF and SV + RV5 and an increase in LVDD during the early phase of follow-up period, and is associated with an increased incidence of VT and a poor prognosis.

[Endoscopic resection of the thoracic sympathetic trunk for the treatment of frequent syncopal attack of idiopathic long QT syndrome]

A 22 year old man was diagnosed as having Jervell and Lange-Nielsen syndrome (JLNS), which includes a prolonged QTc, congenital neural deafness, and syncopal attacks or sudden death. In spite of medication with beta blocker, syncopal attack increased in frequency since his sister suddenly had died of JLNS. Because left stellate ganglion block improved the QTc dispersion, left cardiac sympathectomy was scheduled under the video-assisted thoracic surgery. After the premedication with midazolam, anesthesia was induced with thiamylal, and maintained with nitrous oxide, sevoflurane, and fentanyl. Serious arrhythmias were not observed throughout the perioperative period. Sympathetic trunk was successfully resected from the top of 1st ganglion to the bottom of 4th ganglion of left thoracic sympathetic trunk. Horner's sign did not appear after the surgery. Although the shortening of QTc was not significant, QTc dispersion during exercise was improved, and syncopal attack was not observed until 6 months after the surgery.

[Abnormalities of electrocardiographic P wave morphology and the relationship to electrophysiological parameters of the atrium in patients with idiopathic paroxysmal atrial fibrillation]

In 39 patients with idiopathic paroxysmal atrial fibrillation (PAF group), the incidence of the abnormal P wave morphology (prolonged P wave and mitral P in lead II and increased P terminal force in lead V1: PTF V1) was examined, and the relationships to the electrophysiologic findings of the atrial muscle were investigated. The control group consisted of 42 patients with various cardiac arrhythmias other than sick sinus syndrome. P wave duration was significantly longer in the PAF group than in the control group (112 +/- 12 vs 98 +/- 10 msec, p < 0.0001). PTF V1 was greater in the PAF group than in the control group (0.051 +/- 0.018 vs 0.028 +/- 0.010 msec, p < 0.0001). P mitrale occurred in only 5 patients (12%) in the control group as compared to 25 patients in the PAF group (64%, p < 0.0001). The longest duration of the right atrial electrograms was longer in the PAF group than in the control group (101 +/- 17 vs 85 +/- 10 msec, p < 0.0001), as was the maximal number of the fragmented deflections (8.0 +/- 2.5 vs 5.8 +/- 1.4, p < 0.0001). Repetitive atrial firing zone and also fragmented atrial activity zone were longer in the PAF group than in the control group (34 +/- 24 vs 12 +/- 19 msec, p < 0.02 and 47 +/- 27 vs 24 +/- 19 msec, p < 0.001, respectively). Interatrial conduction delay zone was longer in the PAF group than in the control group (55 +/- 25 vs 38 +/- 18 msec, p < 0.001). P wave duration and PTF V1 had significant and/or borderline correlations with the longest duration of the right atrial electrocardiograms (r = 0.75, p < 0.0001 and r = 0.68, p < 0.0001, respectively), and the maximal number of its fragmented defections (r = 0.50, p < 0.002 and r = 0.40, p < 0.05, respectively). Furthermore, P wave duration had a correlation with the repetitive atrial firing zone (r = 0.55, p < 0.01). Prolonged P wave duration and increased PTF V1 are electrocardiographic indicators for the coexistence of electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation.

Atrial conduction curves in patients with and without atrial fibrillation

In order to quantify underlying atrial conduction properties in patients with atrial fibrillation (AF) using clinical electrophysiology techniques, atrial conduction curves relating intra-atrial conduction times to extrastimulus prematurities during programmed atrial stimulation were drawn. Based on the presence or absence of AF episodes, 95 subjects were divided into 2 groups: control (n=42); and AF (n=53). During programmed stimulation introduced from the right atrial appendage, an atrial conduction curve was drawn for each patient. For most of the control subjects, when the extrastimulus prematurity was increased by 10-ms steps, the intra-atrial conduction times also increased gradually; the maximum stepwise prolongation in intra-atrial conduction time was 11.0+/-3.4 msec. For patients with AF, a 10-msec increase in extrastimulus prematurity often produced a sudden marked prolongation in the intra-atrial conduction time; the maximum stepwise prolongation of intra-atrial conduction time was 21.4+/-5.9 msec. In contrast to the gradual atrial conduction curves recorded in control subjects, the sudden prolongation of intra-atrial conduction time was remarkable on the curves obtained in patients with AF. Statistical significance was clearly established (p<0.0001). This difference could be related to differences in the underlying conduction properties in patients with and without AF.

Thromboembolic complication in atrial fibrillation in a long-term follow-up--the relationship with underlying disease, type of atrial fibrillation, and antithrombotic therapy

The incidence of thromboembolic complications among 288 patients with atrial fibrillation (AF) who were followed up during an average period of 7.2 years was examined retrospectively. The annual incidence of thromboembolic complications was 1.6% in total, 1.7% in valvular heart disease (n=128), and 2.1% in non-valvular heart disease (n=117). No thromboembolism occurred in lone AF (n=43), defined as the complete absence of any underlying disease. The type of AF before embolic attack was chronic in 26 cases and paroxysmal in 6 cases. The cardiac rhythm at the time of the embolic attack was AF, except in 2 cases in which ECG was not recorded. In all patients with thromboembolic complications who were receiving antithrombotic therapy during the follow-up, the anticoagulant effect just before the embolic attack was found to be insufficient. Major bleeding was not observed in the patients receiving antithrombotic therapy. Thromboembolism in AF in long-term follow-up tends to occur more frequently in patients with underlying heart disease and in those with chronic AF compared rather than paroxysmal AF; it rarely occurs in lone AF. We should not hesitate to administer sufficient anticoagulant therapy in AF patients who are at high risk of developing thromboembolic complications.

Abnormalities of electrocardiographic P wave morphology and their relation to electrophysiological parameters of the atrium in patients with sick sinus syndrome

We examined the incidence of long P wave duration in lead II and increased P terminal force in lead V1 (PTFV1), and their relationship to electrophysiological findings of atrial muscle in 34 patients with sick sinus syndrome (SSS). Patients were divided into three groups: Group I, consisting of 20 patients with various cardiac arrhythmias other than SSS and paroxysmal atrial fibrillation (PAF) who served as controls; Group II, consisting of 18 patients with SSS but without PAF; and Group III consisted of 16 patients with SSS and PAF. P wave duration was significantly longer in Group III (122 +/- 11 ms, mean +/- SD, P < 0.0001) and Group II (111 +/- 15 ms, P < 0.002) than in Group I (98 +/- 10 ms). PTFV1 was greater in Group III (0.052 +/- 0.025 ms) than in Group I (0.028 +/- 0.011 ms, P < 0.05). P wave duration and PTFV1 had significantly and/or borderline correlations with longest duration of right atrial electrograms (r = 0.84, P < 0.0001 and 0.47, P < 0.02, respectively), maximal number of fragmented deflections of atrial electrograms (r = 0.69, P < 0.0001 and r = 0.51, P < 0.02, respectively), repetitive atrial firing zone (RAFZ) (r = 0.81, P < 0.0001 and 0.48, P < 0.05, respectively) and fragmented atrial activity zone (FAAZ)(r = 0.53, P < 0.01 and r = 0.45, P = 0.06, respectively). We concluded that long P wave duration and increased PTFV1 are electrocardiographic indicators for coexistence of electrophysiological abnormalities in the atria in SSS without recognizable heart disease.

Evidence of three clinical subgroups in patients with dual atrioventricular nodal pathways

We attempted to test the hypothesis that dual atrioventricular (A-V) nodal pathways with second-degree atrioventricular block (2nd A-V block) present as a different clinical entity from those with A-V nodal reentranttachycardia (AVNRT). By evaluation with Holter monitoring (2.9 +/- 2.5 recordings/patient) and 12-lead electrocardiogram (11.9 +/- 11.6), 177 patients with dual A-V nodal pathways could be divided into three subgroups. Thirty-two patients had 2nd A-V block only (2nd A-V block group), 57 had AVNRT only (AVNRT group), 88 had neither 2nd A-V block nor AVNRT (silent group), and none had 2nd A-V block and AVNRT both. Electrophysiologic studies showed that the atrio-His interval was significantly greater (P < 0.0001) and the maximal 1:1 atrioventricular conduction rate was lower (P < 0.0001) in the 2nd A-V block group than in the other two groups. These differences were nullified after the administration of atropine. These results suggest that patients with dual A-V nodal pathways can be classified into three clinical subgroups based on the presence of either 2nd A-V block or AVNRT. We suggest also that patients of the 2nd A-V block group may have a more augmented vagal tone on the A-V node than the other two groups.

Temporal lobe lesion demonstrating features of dysembryoplastic neuroepithelial tumor and ganglioglioma: a transitional form?

We report an unusual multimodular glioneuronal lesion found in a temporal lobe from a 17-year-old boy with complex partial seizure. Histologically, this lesion was located within the cortex of the middle temporal gyrus and consisted of multinodular foci and the surrounding cortical dysplasia, resembling dysembryoplastic neuroepithelial tumor (DNT). However, it was quite different in the following respects from usual DNT: 1 nodule found in the subpial area consisted entirely of mature atypical neuronal cells separated by a reticulin fiber network connecting to the pia mater and the area around and between the above nodule, whereas another neighboring nodule, which contained many oligodondroglia-like round cells as well as occasional neuronal cells and fibrillary astrocytic cells, showed scattered neuronal cells in the well-differentiated fibrillary astrocytic stroma, the histological features being those of ganglioglioma (GG). We consider that the present case is a good example of the transitional form between DNT and GG. At 25 months following total lesion extirpation, the patient is healthy and free from seizures.

Melanotic cerebral astrocytoma: case report and literature review

We describe the case of 47-year-old man with a cystic, melanotic temporal lobe astrocytoma who had a history of complex partial seizures. The tumor mass was made up of two histologically different regions: one consisted of spindle-shaped and pleomorphic cells often with foamy or vacuolated cytoplasm, while the other consisted of fairly uniform spindle-shaped cells, many of which contained dark-brown intracytoplasmic pigment. Desmoplasia was also noted in the latter region of the tumor. No features suggestive of malignancy, such as mitotic figures, necrotic foci or endothelial vascular proliferation, were observed throughout the tumor. Immunohistochemically, the tumor cells in both regions were positive for glial fibrillary acidic protein. Ultrastructural examination of the pigmented region showed the presence of melanosomal melanin in the tumor cells. Apart from the partial pigmentation, the entire histological picture resembled a pleomorphic xanthoastrocytoma. To our knowledge, only two cases of similar melanotic astrocytic tumors have been described previously. Interestingly, the astrocytic tumors in both of these patients were also clinically associated with epilepsy, were located in the temporal lobe, and were histologically benign.

[Signal transduction system in cardiac cells]

The electrical excitation and conduction in the heart is due to ionic events via ion channels and gap junctions. Function of these channels and gap junctions is regulated by intracellular milieu, which is regulated by many kinds of receptors through intracellular second messengers i.e.; GTP binding proteins, protein kinases, Ca2+ concentrations, H+ concentration, cyclic nucleotides and triphosphate nucleotides. In this paper, we focus on signal transduction systems in cardiac myocytes. Subsequently, some of interactions between signal transduction systems are introduced.

Dose-response relationship between urinary cadmium concentration and beta2-microglobulinuria using logistic regression analysis

Logistic regression analysis was used to investigate the dose-response relationship for environmental cadmium exposure and to consider the effect age had on this association. The target population comprised 3178 inhabitants of Japan who were more than 50 y of age and who lived in a cadmium-polluted area and 1134 inhabitants who lived in nonpolluted areas of Japan. Logistic regression analysis was completed on the dose-response relationship between urinary cadmium concentration (i.e., an indicator of cadmium body burden) and beta2-microglobulinuria (i.e., an index of renal tubular dysfunction caused by exposure to cadmium). Both age and urinary cadmium concentration were associated significantly with beta2-microglobulinuria. Based on the relationship that was determined, we calculated, by age and sex, the values of urinary cadmium concentration that corresponded to the prevalence rates of beta2-microglobulinuria in the nonpolluted population. The resulting values were 1.6-3.0 micrograms/g creatinine for men and 2.3-4.6 micrograms/g creatinine for women.

Effects of degraded schizophyllans on regeneration of protoplast cells of Saccharomyces cerevisiae

Schizophyllan was heated at 100 degrees C in 85% dimethyl sulfoxide (DMSO) containing 0.01 M H2SO4 for various times, and fractionated by gel-permeation chromatography. Molecular weights (M(r)) of the depolymerized products thus obtained were measured in water and DMSO by GPC-LALLS to estimate their conformations in water. The products with triple helical structure stimulated regeneration of Saccharomyces cerevisiae protoplast cells, while those of single chain conformation were totally inactive.

Electrophysiological effects of MS-551 in humans: a class III antiarrhythmic agent

To investigate the clinical effects of MS-551, a Class III antiarrhythmic agent, 11 patients underwent electrophysiological study. MS-551 was given intravenously as an initial dose of 0.2 or 0.3 mg/kg for 5 minutes followed by the continuous infusion at 0.2 or 0.3 mg/kg for 30 minutes, respectively, in all patients. The rate corrected QT interval increased significantly from 3 minutes after the beginning of MS-551 infusion. The sinus heart rate decreased significantly by 8% at 10 minutes after the drug administration (P < 0.025). Mean PR and QRS intervals, and blood pressure were not significantly affected by the drug. Mean PA, AH, and HV intervals during sinus rhythm were also not affected. The effective refractory periods (ERPs) of the atrium and ventricle were significantly prolonged by 13% from 202 +/- 24 ms to 231 +/- 26 ms (P < 0.0005), and by 7% from 238 +/- 11 ms to 257 +/- 13 ms (P < 0.002), respectively, by MS-551. The ERP of the atrioventricular node and sinoatrial nodal recovery time were not changed significantly by the drug. This is a report of the effects of MS-551 in humans. This agent could be useful for treatment of tachyarrhythmias by prolongation of ERPs of the atrium and ventricle without significant variations of blood pressure and intracardiac conduction times. It is noteworthy that MS-551 slightly but significantly decreased heart rate.

Significance of elevated urinary human intestinal alkaline phosphatase in Japanese people exposed to environmental cadmium

Urinary human intestinal alkaline phosphatase (IAP), beta 2-microglobulin (beta 2-MG) and N-acetyl-beta-D-glucosaminidase (NAG) were analyzed in 40 Japanese environmental-cadmium (Cd)-exposed and 40 non-exposed subjects to evaluate early biological markers for Cd-induced renal damage. All urinary indicators were significantly higher in the Cd-exposed subjects than non-exposed subjects. A fourth-order function was fitted for the relationship between beta 2-MG and IAP or NAG. The beta 2-MG concentration corresponding to the inflexion point for IAP was smaller than that for NAG. This result may support the contention that the cells containing IAP are damaged earlier than those containing NAG, and that IAP is a useful marker for detecting renal tubular dysfunction in people moderately exposed to Cd. However, in the stage of severe renal damage, the combination of IAP and beta 2-MG is considered to be more useful.

Effects of aprindine on electrophysiological properties of the atrial muscle in man

The effects of aprindine on atrial vulnerability were studied in 11 patients; 9 with paroxysmal atrial fibrillation (PAF), and 2 with Wolff-Parkinson-White syndrome, aged 19 to 69 (55.9 +/- 16.5; mean +/- SD). Before and 10 min after the intravenous injection of aprindine (1.5 mg/kg), programmed extrastimulation was performed from the right atrial appendage. Atrial vulnerability was assessed by evaluating the repetitive atrial firing zone (RAFZ), conduction delay zone (CDZ), maximum conduction delay (Max. CD) and fragmented atrial activity zone (FAAZ). After the injection, the duration of the P wave and QTc interval was significantly prolonged without any change in blood pressure or heart rate. RAF was observed in 8 patients under control conditions. However, after the injection of aprindine, the RAFZ completely disappeared in 2 patients, was narrowed in 4, and became wider in 1. AF was induced in the remaining patient. The zone significantly reduced (p < 0.01) without any change in CDZ or Max. CD. While FAA was observed in 5 patients under control conditions, it completely disappeared in 2 patients, was narrowed in 1, and did not change in the remaining 7 after the injection of aprindine. In patients whose RAFZ narrowed after administration of aprindine, the wavelength, as determined from the atrial effective refractory period and conduction velocity, was augmented. These results indicate that aprindine suppresses atrial vulnerability with an augmentation of the wavelength. However aprindine exaggerated atrial vulnerability in some patients, such that atrial fibrillation was induced.

Radiofrequency catheter ablation for atrioventricular node reentry tachycardia with multiple slow atrioventricular node pathways

Catheter ablation was attempted in 2 patients with atrioventricular node reentry tachycardia which showed fast, intermediate and slow anterograde atrioventricular node pathways. Radiofrequency currents were applied within a restricted area of the tricuspid annulus between the His bundle and the ostium of the coronary sinus where presumed slow pathway potentials were identified. Elimination of both the intermediate and the slow pathways, with preservation of anterograde and retrograde fast pathway conduction, was achieved in both patients.

Possible role of supernormal atrial conduction in the genesis of atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation

OBJECTIVE

The occurrence of supernormal excitability and conduction in the atrium has been attributed to the internodal pathways in several animal experiments. However, little is known about the role of supernormal atrial conduction (SNC) in the genesis of arrhythmias. The specific aim of this study was to evaluate prospectively the relationship between SNC, atrial conduction defects and atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation.

METHODS

Programmed atrial stimulation was performed in 38 control patients (group 1), and 21 patients with idiopathic paroxysmal atrial fibrillation (group 2) to assess some determinants of atrial conduction defects, SNC, and atrial fibrillation inducibility.

RESULTS

The mean P-wave duration was 99 +/- 8 ms in group 1, and 110 +/- 12 ms in group 2; p < 0.001. The maximum interatrial conduction delay was 36 +/- 40 ms in group 1, and 56 +/- 21 ms in group 2; p < 0.005. Supernormal atrial conduction was observed in 27 (71 percent) patients of group 1, and in 5 (24 percent) of group 2; p < 0.0003. The SNC zone was 70 +/- 29 ms in group 1, and 16 +/- 31 ms in group 2; p < 0.0001. The maximum decrease in conduction time during the period of SNC was 12 +/- 4 ms in group 1 and 3 +/- 6 ms in group 2; p < 0.0005. The SNC zone showed a significant inverse correlation with the P-wave duration (r = -0.53; p < 0.0005), and with the maximum conduction delay (r = -0.38; p < 0.005).

CONCLUSIONS

Patients with idiopathic paroxysmal atrial fibrillation have a significantly decreased incidence of SNC than controls. There is an inverse relation between the atrial conduction defects and the SNC. The association of the absence of SNC with defects in atrial conduction may play some role in the development of atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation.