The morphology of the atrioventricular node in scleroderma -- a three-dimensional reconstruction

A new technique for looking at the atrioventricular node andbundle is described and applied to the conducting system insix patients with scleroderma. The conducting system blockswere removed, sectioned, appropriately stained and photographed.Outlines of the atrioventricular node and bundle were generatedand digitized. From the digital information three-dimensionalimages were generated and the atrioventricular node and bundlewere rotated so that the shape could be studied from any view.In striking contrast to normal atrioventricular nodal reconstructions,those from the patients who had scleroderma showed a narrowand flattened proximal atrioventricular node. The nodal microscopy,on the other hand, did not differ significantly in architecture.It is postulated that the alterations by fibrous replacementof the proximal node could account for the relatively high frequencyof atrioventricular conduction Scleroderma, problems in patientswith scleroderma and could paradoxically account for the relativelyfrequent occurrence of supraventricular tachycardias that arealso found in this disease.     

Functional renal involvement in normotensive patients with progressive systemic sclerosis. impaired sodium excretion during isotonic saline infusion

An intravenous infusion of 2,000 ml isotonic saline was performed in 8 normotensive, normoreninemic patients with progressive systemic sclerosis. None of them had clinical evidence of renal disease. Total and proximal fractional excretion of sodium was reduced when compared with that of 8 normal subjects. No correlation was found with para-aminohippurate (PAH) clearance values. Two years after this study was done, 4 patients developed arterial hypertension; interestingly, plasma renin activity remained within the normal range. Reduced sodium excretion is suggested as having a pathogenetic role in the hypertension of progressive systemic sclerosis.     

Multiple reentry tachycardia in patients with ventricular preexcitation: report of three cases

The electrophysiologic studies of three patients with accessory pathways and multiple reentrant circuits are reported. The first patient had two atrioventricular accessory pathways: a left posterior capable of bidirectional conduction and a right paraseptal with retrograde conduction only. Four atrioventricular reentry circuits were documented: left and right orthodromic circuits and a left antidromic circuit with retrograde conduction over the right paraseptal accessory pathway. The second patient had a left lateral atrioventricular accessory pathway with type A preexcitation. Two reentrant tachycardias were noted: an atrial tachycardia where the accessory pathway remained concealed and an orthodromic atrioventricular tachycardia. The third patient had dual atrioventricular nodal pathways and a right nodofascicular accessory pathway. The accessory pathway became manifest only when a critical atrioventricular delay was reached, indicating its association with the slow atrioventricular nodal pathway. Wide QRS tachycardia with left bundle branch block contour was documented, by means of the slow atrioventricular nodal pathway and nodofascicular fiber antegradely, and the proximal right bundle branch, the His bundle, and the fast atrioventricular nodal pathway retrogradely.     

Effect of autonomic nervous system modulation on retrograde atrioventricular nodal conduction in the human heart

Although the influence of the autonomic nervous system on anterograde atrioventricular nodal conduction is well established, its effect on retrograde atrioventricular nodal conduction has not been examined systematically. Since retrograde atrioventricular nodal conduction in subjects with normal anterograde conduction may vary from intact retrograde conduction to complete retrograde block when assessed during ventricular pacing, in this study patients with (a) intact retrograde atrioventricular nodal conduction (group 1) were studied during parasympathetic (vagal) stimulation by carotid sinus pressure and during sympathetic inhibition (propranolol 0.2 mg.kg-1 intravenously) and (b) retrograde atrioventricular nodal block (group 2) were studied during vagal blockade (atropine 0.04 mg.kg-1 intravenously) and during sympathetic stimulation (isoproterenol 1-4 micrograms.min-1 infusion). In both groups changes in sinus cycle length and anterograde atrioventricular nodal conduction were measured. In group 1 vagal stimulation by carotid sinus pressure in 20 patients caused the cycle length at which retrograde atrioventricular nodal block was induced to be significantly lengthened from a mean(SD) of 375(59) to 451(51) ms in six patients; caused complete retrograde block in 10 patients; and had no effect in four patients. Sympathetic inhibition by propranolol in another 15 patients delayed the onset of pacing induced retrograde atrioventricular nodal block from a mean(SD) of 340(60) to 418(80) ms in 11 patients; caused complete retrograde atrioventricular nodal block in three patients; and had no effect in one patient. In group 2 vagal blockade by atropine caused a 1:1 retrograde response during ventricular pacing up to a mean(SD) cycle length of 470(135) ms in six out of eight patients. The infusion of isoproterenol caused the retrograde atrioventricular nodal block to be abolished and 1:1 conduction to be resumed up to a ventricular pacing mean(SD) cycle length of 364(57) ms in six out of eight patients. It is concluded that (a) the autonomic nervous system modulates retrograde atrioventricular nodal conduction in a similar manner to its anterograde counterpart and (b) that since retrograde atrioventricular nodal conduction was reversible after the administration of either atropine or isoproterenol retrograde atrioventricular nodal block may be dynamic (physiological) rather than fixed (anatomical) in nature.     

Atrial conduction abnormalities in patients with systemic progressive sclerosis

BACKGROUND: Atrial abnormalities in patients with progressive systemic sclerosishave not been evaluated in terms of intra-artrial conduction.We hypothesized that a delay in atrial conduction in these patientsmight produce diastolic abnormalities as well as atrial arrhythmias. OBJECTIVE: To evaluate the atrial function of patients with progressivesystemic sclerosis by using echocardiography to measure theintra-atrial electromechanical activation coupling interval. METHODS: Twenty patients with progressive systemic sclerosis were assessedby Doppler echocardiography. Twenty age-matched healthy controlswere also evaluated. Two-dimensional guided M-modes of ventricularlong axes were recorded using simultaneous phono- and electrocardiogramsof the apical four chamber view at the right lateral, septaland left lateral sites of the atrioventricular rings. Transmitraland tricuspid pulsed Doppler flow velocities were also recorded.Filtered P wave duration was measured on the signal averagedECG to determine the duration of atrial electrical activation. RESULTS: There was a delay in P on the electrocardiogram (P) at the onsetof atrial contraction on long axis M-modes at all three atrioventricularring sites in patients with progressive systemic sclerosis ascompared with controls (P-right; 56±13 vs 47±10ms, P-septal; 74±14 vs 55±10 ms, and P-lateral;93±16 vs 72±11 ms, P<0·01). Inter-atrialconduction time [(P-lateral) — (P-right)] was delayedin patients with progressive systemic sclerosis, compared withhealthy controls (37±15 vs 25±6 ms, P<0·01).Mitral A waves acceleration and deceleration times were alsodecreased in the patients. The interval was prolonged betweenP to the onset and the peak of the A wave in transmitral flow.Duration of the filtered P wave was significantly prolongedin progressive systemic sclerosis as compared with controls(124±12 ms vs 106±8 ms, P<0·01). PQintervals, E waves and acceleration and deceleration times didnot differ significantly in progressive systemic sclerosis vs,controls. The A wave acceleration rate on transmitral flow (peakA wave velocity/acceleration time) showed a significant correlationwith inter-atrial conduction delay (r=0·55, P<0·01). CONCLUSIONS: Intra-atrial electromechanical coupling intervals were delayedin patients with progressive systemic sclerosis. Thus, the mechanicallate diastolic filling time due to atrial contraction in thetotal diastolic phase was severely limited, and this resultedin a restricted mitral A wave. We should therefore evaluatepatients with progressive systemic sclerosis for significantatrial abnormalities.     

Early atrial fibrillation during evolving myocardial infarction: a consequence of impaired left atrial perfusion

Seven of 214 patients (3%) with acute myocardial infarction (120 inferior and 94 anterior) developed atrial fibrillation within 3 hr of the onset of chest pain. All seven patients had an inferior infarction and in all seven the left circumflex artery was occluded proximal to the origin of its left atrial circumflex branch. In five patients this occlusion was acute and was the cause of inferior infarction and in the remaining two patients the occlusion was old and the inferior infarction was due to an acute occlusion of the right coronary artery that also supplied extensive collaterals to the previously occluded left circumflex artery. All seven patients also had impaired perfusion to the atrioventricular nodal artery, as evidenced by total occlusion proximal to its origin or by stenosis proximal to its origin associated with second- or third-degree atrioventricular block. In contrast, early atrial fibrillation did not occur in any of the 18 patients with inferior myocardial infarction due to acute occlusion of the distal left circumflex artery or in any of the five patients with inferior infarction due to acute occlusion of the proximal left circumflex artery if perfusion to the atrioventricular nodal artery was not impaired. Early atrial fibrillation did not occur in any of the 90 patients with inferior infarction due to acute occlusion of the right coronary artery, including 12 patients with occlusion proximal to the sinus nodal artery, but without coexistent occlusion of the left circumflex artery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gastrointestinal systemic sclerosis in serologic mixed connective tissue disease

Mixed connective tissue disease is a clinical entity defined by overlapping features of progressive systemic sclerosis, systemic lupus erythematosus, polymyositis, rheumatoid arthritis, and distinct serologic findings. Esophageal dilatation and dysmotility have been the only gastrointestinal manifestations reported. Three patients with serologic findings of mixed connective tissue disease and extensive gastrointestinal involvement compatible with the changes found in progressive systemic sclerosis are presented. Gastrointestinal manifestations of progressive systemic sclerosis are reviewed and were found to be indistinguishable from the findings in these patients.     

Autologous and allogeneic mixed lymphocyte reactions in progressive systemic sclerosis

The autologous and allogeneic mixed lymphocyte reactions (MLR), observed when peripheral blood mononuclear cells from 20 patients with progressive systemic sclerosis were used, were compared with those of age-, sex-, and race-matched normal controls. Such cells were separated by gradient centrifugation of sheep red blood cell (E) rosettes into stimulator (E- or non-T cell) and responder (E + or T cell) populations. The autologous MLR of both the progressive systemic sclerosis and normal peripheral blood mononuclear cells varied widely but there was no statistical difference between the means of each group. In the allogeneic MLR, proliferation between progressive systemic sclerosis non-T cells and normal T cells was significantly less than that of normal non-T cells and progressive systemic sclerosis T cells (P = 0.001). A decreased autologous MLR, while noted with other autoimmune diseases, was lacking in progressive systemic sclerosis. This suggests a different defect. The differences in the allogeneic MLR also suggest that either progressive systemic sclerosis non-T cells were poor stimulators or T cells associated with this disease were better responders when compared with similarly prepared cell populations from normal individuals. The MLR differences could have also resulted from compositional subset alterations or the sharing of a common antigen. HLA-DR5 was found in 9 of the 17 white patients with progressive systemic sclerosis. Although these individuals were evenly distributed as low, medium, and high responders, this finding showed that some progressive systemic sclerosis non-T cells shared a common antigen.     

Syncope due to paroxysmal atrioventricular block in a patient with systemic sclerosis: a case report

A 79-year-old woman with systemic sclerosis was admitted to our hospital because of syncope. On admission, electrocardiogram showed progression of intraventricular conduction defect. Chest radiograph showed marked cardiomegaly. Echocardiogram revealed deterioration of left ventricular systolic function. We suspected progressive myocardial disease with Stokes-Adams attack. When we were preparing a temporary pacemaker, paroxysmal atrioventricular block with asystole for 15 seconds and convulsion occurred. Electrophysiological study showed His-ventricular block and sinus node dysfunction. A permanent pacemaker was implanted. In systemic sclerosis, progression of ventricular conduction defect may warrant prompt electrophysiological study and prophylactic pacemaker implantation.     

射频消融房室交界区慢、快经区域对犬和人心房颤动时心室率的影响

本文观察经导管射频消融房室交界区慢、快径区域对大和人心房颤动时心室率的影响.方法 杂种犬4条,体重11±1.2kg.房室结折返性心动过速患者7例,年龄29～65岁.阵发性房颤患者4例,年龄62～70岁,其中2例为短P-R间期综合征.均先采用“下位法”消融慢径区域后,若房室结有效不应期或房颤时平均R-R间期无明显变化,则加行“快径”区域消融.房颤诱发采用猝发脉冲电刺激(人)或静滴氯化乙酰胆碱后猝发脉冲电刺激(犬).结果 7例房室结折返性心动过速患者中5例经下位法射频消融阻断慢径,房室结前传有效不应期及诱发房颤时平均R-R间期明显延长(222±33ms vs 285±42ms和539±44ms vs 656±53ms P<0.01),无并发症.4条大及4例阵发性房颤患者经心内电生理检查证实均无房室结双径路表现,选择性消融“慢径区域”后,房室结有效不应期和房颤时平均R—R间期无明显变化,加行“快径区域”消融后,房室结有效不应期和房颤时平均R—R间期明显延长(犬145±16ms vs 185±22ms和305±13ms vs 403±17ms P<0.01,人220ms vs 490ms和367ms vs 690msP<0.01),1例房颤患者术后3天出现Ⅲ°AVB,2周后恢复为Ⅰ°AVB.本文还在动物实验中观察到消融快径区域时,房侧靶点(A/V>1)较室侧靶点(A/V<1)更易于造成Ⅲ°AVB.结论 选择性射频消融慢径区域对减?     

Exocrine pancreatic function in patients with progressive systemic sclerosis

The exocrine pancreatic function was investigated in 16 patients with progressive systemic sclerosis by means of a meal test (Lundh test) and in 9 of the patients by the secretin-cholecystokinin test as well. Gastrointestinal involvement with progressive systemic sclerosis was evaluated by esophageal manometry and by routine roentgenographic series of the small bowel. Fecal fat excretion measurement, the D-xylose absorption test, and a small-intestinal biopsy procedure were carried out. Duodenal juice was cultured and bacterial counts were estimated. One-third of the patients had reduced exocrine pancreatic function, but only four patients had unequivocally a reduction that could be of clinical importance. The results obtained with the meal test were in accordance with the secretin-cholecystokinin test, indicating a preserved capacity for endogenous stimulation.     

Solid-phase radionuclide esophageal transit in progressive systemic sclerosis

BACKGROUND/AIMS: In most patients with progressive systemic sclerosis the esophagus is affected. Reflux symptoms are most frequent whilst dysphagia also occurs. The radionuclide esophageal transit study is a sensitive screening test for esophageal dysfunction. In this study, we evaluated the esophageal motility of patients with progressive systemic sclerosis using a solid-phase radionuclide esophageal study. METHODOLOGY: Thirty-two patients with progressive systemic sclerosis and 30 normal volunteers were studied with solid-phase radionuclide esophageal study. Each subject was placed in a supine position above a gamma camera linked to a computer and was given a 4-mL bolus of solid gelatin containing 1 mCi of Tc-99m phytate. Data were acquired in the list mode. RESULTS: Twenty-nine of the 32 patients (91%) had abnormal findings from the study. CONCLUSIONS: The radionuclide esophageal transit study can be regarded as a useful tool for evaluating the esophageal function in patients with progressive systemic sclerosis and in the follow-up of treatment.     

Enterocyte function in progressive systemic sclerosis as estimated by the deconjugation of pteroyltriglutamate to folic acid.

As a measure of enterocyte function, the deconjugation of pteroyl-L-glutamyl-gamma-L-glutamyl-gamma-L-glutamic acid to folic acid and subsequent active absorption was measured in 19 patients with progressive systemic sclerosis and compared with 14 controls. The absorption step of folic acid was identical in the two groups, while deconjugation of pteroyl-L-glutamyl-gamma-L-glutamyl-gamma-L-glutamic acid was significantly decreased in the patients with progressive systemic sclerosis. This observation suggests a primary epithelial defect of the small intestine in patients with progressive systemic sclerosis.     

The electrophysiology of atrioventricular nodal reentry tachycardia following the Mustard or Senning procedure and its radiofrequency ablation

We describe the electrophysiological studies undertaken in four patients with atrioventricular nodal reentry tachycardia in the setting of concordant atrioventricular and discordant ventriculo-arterial connections (transposition). Radiofrequency ablation was attempted in three, all with success. Clear evidence of dual antegrade pathways through the atrioventricular node was present in only one of the four, but other characteristics of discrete fast and slow pathways into the atrioventricular node were present in all. Atrioventricular nodal reentry tachycardia was inducible in all. In the three patients in whom ablation was attempted, the application of radiofrequency energy to the low medial regions of the systemic venous atrium (morphologically left) consistently caused junctional accelerated rhythm, but these lesions were not successful in eliminating the tachycardia. Successful radiofrequency ablation required a retrograde approach to the region of the slow pathway in the pulmonary venous atrium (morphologically right).     

His bundle electrogram in patients with acute myocardial infarction complicated by atrioventricular or intraventricular conduction disturbances.

Seventy-two patients with acute myocardial infarction complicated by atrioventricular or bundle-branch block or a combination of both had His bundle electrogram studies performed during their stay in the coronary care unit. In 19 of the 72 patients a repeat His bundle electrogram was performed before discharge from hospital. These studies demonstrated that 30 of the 32 patients with atrioventricular block and narrow QRS complexes had a block above the origin othe His spike (proximal block). Eleven patients in this group had repeat His bundle electrograms performed before discharge and in 3 patients there was evidence of residual atrioventricular nodal dysfunction. Both the hospital and follow-up mortality in this group was low and there was no evidence to suggest that permanent pacing would benefit these patients. Of the 18 patients with bundle-branch block and a normal PR interval, 9 had prolongation of the HV interval, but there was no difference in mortality in patients with normal or prolonged HV intervals. Twenty-two patients with bundle-branch block also developed atrioventricular block. In 5 of these patients the site of the AV block was proximal and in 14 it was distal, while 3 patients had both proximal and distal block. The hospital mortality in those patients who progressed to second- or third-degree atrioventricular block was considerably higher than in those patients who remained in first-degree atrioventricular block.     

His bundle electrogram in patients with acute myocardial infarction complicated by atrioventricular or intraventricular conduction disturbances.

Seventy-two patients with acute myocardial infarction complicated by atrioventricular or bundle-branch block or a combination of both had His bundle electrogram studies performed during their stay in the coronary care unit. In 19 of the 72 patients a repeat His bundle electrogram was performed before discharge from hospital. These studies demonstrated that 30 of the 32 patients with atrioventricular block and narrow QRS complexes had a block above the origin othe His spike (proximal block). Eleven patients in this group had repeat His bundle electrograms performed before discharge and in 3 patients there was evidence of residual atrioventricular nodal dysfunction. Both the hospital and follow-up mortality in this group was low and there was no evidence to suggest that permanent pacing would benefit these patients. Of the 18 patients with bundle-branch block and a normal PR interval, 9 had prolongation of the HV interval, but there was no difference in mortality in patients with normal or prolonged HV intervals. Twenty-two patients with bundle-branch block also developed atrioventricular block. In 5 of these patients the site of the AV block was proximal and in 14 it was distal, while 3 patients had both proximal and distal block. The hospital mortality in those patients who progressed to second- or third-degree atrioventricular block was considerably higher than in those patients who remained in first-degree atrioventricular block.     

Concept of the polyfascicular structure of the atrioventricular junction in patients with reciprocal paroxysmal nodal tachycardias

Intracardiac electrophysiologic studies were carried out in 41 patients with paroxysmal supraventricular tachycardias. Reciprocal atrioventricular tachycardia due to dissociated conduction through the atrioventricular junction was diagnosed in 29 patients. Electrophysiologic data suggested trifascicular atrioventricular conduction in 4 patients, and quadrifascicular conduction in 2. A concept of polyfascicular impulse conduction through the atrioventricular junction in some cases of reciprocal nodal tachycardia is proposed. It is demonstrated that combinations of congenital cardiac conduction abnormalities may be possible in the same individual.     

'Dual atrioventricular nodal pathways" in patients with Wolff-Parkinson-White syndrome.

'Dual atrioventricular nodal pathways" were found in five patients who also had the Wolff-Parkinson-White syndrome. All five patients had a re-entrant tachycardia that used the atrioventricular node for conduction in the anterograde direction and an accessory atrioventricular pathway for conduction in the retrograde direction. One of the patients also had a re-entrant tachycardia that originated within the atrium or the atrioventricular node. Dual atrioventricular nodal pathways were identified in three of the five patients during their first electrophysiological study because the effective refractory period of the accessory atrioventricular pathway in the anterograde direction was longer than the effective refractory period of the fast atrioventricular nodal pathway. In the other two patients the dual atrioventricular nodal pathways were found only after operative division of an accessory atrioventricular pathway. Re-entrant tachycardia that uses an accessory pathway may be cured by operative division of the accessory pathway. Tachycardia resulting from re-entry within the atrioventricular node cannot be cured by an operation unless the normal conduction system is divided and a permanent pacemaker implanted. These five patients indicate the importance of determining the aetiology of tachycardia by studying the tachycardia itself and not only the type of atrioventricular conduction present.     

Mechanisms of junctional tachycardia showing ventricular pre-excitation.

Over a period of five years 12 patients underwent electrophysiological studies for the investigation of recurrent tachycardias which showed ventricular pre-excitation. Nine patients had a type B pattern and two a type A. One patient had episodes of both types. Dual atrioventricular nodal pathways were found in six of seven patients with atrioventricular nodal re-entrant tachycardia mechanisms. Single direct atrioventricular accessory pathways were present in four patients, single nodoventricular pathways in five, and multiple pathways in three. Twenty one tachycardias were induced, of which 13 showed ventricular pre-excitation. Five patients had nodoventricular pathway conduction during atrioventricular nodal tachycardia and one during atrioventricular re-entrant tachycardia. Only three patients had simple antidromic tachycardia and one additional atrioventricular nodal tachycardia with bystander atrioventricular accessory conduction. Three patients had three different tachycardias, three had two types, and six had one type. Thus junctional tachycardias showing ventricular pre-excitation are often associated with multiple mechanisms and complex anatomical and functional substrates. An accessory pathway was an essential component in only six of 13 tachycardias showing ventricular pre-excitation. Determination of the tachycardia mechanism requires detailed study and analysis.