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At least 127 records · Page 7Linked to original sources
PubMed1991

[The detection of changes in intra-atrial conductivity (based on enhanced ECG data)].

The 20-fold enhanced ECG (without frequency filtration of the signal) was recorded in 30 normal men aged 18 to 36 years. A study was made of the constancy of the P wave forms on the ECG. The P wave form underwent changes in 8 test subjects: in 5 during breathing retention on expiration and in 3 during superficial breathing. The changes indicated are viewed as a manifestation of intraatrial conduction disorders. It is assumed that the changes in the tone of the autonomic nervous system and myocardial hypoxia may contribute to the detection of latent disorders in the cardiac activity.

Adolescent↗
PubMed1976

Ventriculo-atrial conduction time during reciprocating tachycardia with intermittent bundle-branch block in Wolff-Parkinson-White syndrome.

Records from patients with the Wolff-Parkinson-White syndrome were reviewed with particular emphasis on the occurrence of bundle-branch block aberration during reciprocating tachycardia and the significance of this observation with respect to accessory pathway location. Increase by greater than 25 ms in the ventriculoatrial interval during reciprocating tachycardia with bundle-branch block, when compared to reciprocating tachycardia with normal intraventricular conduction, occurred only with right or left free wall accessory pathways. No patient with a septal accessory pathway proven by epicardial mapping showed a ventriculoatrial interval prolongation greater than 20 ms during bundle-branch block aberration. Measurement of ventriculo-atrial interval during bundle-branch block abe-ration also helped to diagnose accessory pathways AH and HV intervals as well as ventriculo-atrial times, may give midleading information. In one patient increase in cycle length during left bundle-branch block was the result of prolonged HV interval rather than prolonged ventriculo-atrial interval. In another patient cycle length remained the same during bundle-branch block while the ventriculo-atrial interval increased by an increment identical to the decrease in AH interval.

Bundle-Branch Block↗
PubMed2000

Resumption of right atrial isthmus conduction following atrial flutter radiofrequency ablation.

Right atrial isthmus block is currently accepted as a success criterion of atrial flutter ablation. An electrophysiological study performed days after the ablation procedure may show recovery of conduction across the isthmus in some patients, followed by arrhythmia recurrence. However, few data are available on the time course of this recovery and on the monitoring of isthmus conduction at the end of the ablation procedure as a means of increasing the success rate of the procedure. Radiofrequency (RF) catheter ablation was performed in 28 men and 7 women (mean age = 65 +/- 11 years) presenting with common or clockwise atrial flutter (AFL) resistant to 2.9 +/- 1.8 antiarrhythmic drugs. Underlying heart disease was present in 13 patients. The ablation procedure was performed with an 8-mm-tip catheter, by several 45-second applications at a target temperature of 65 degrees C, directed to the isthmus between tricuspid annulus and inferior vena cava. Bidirectional isthmus block (BDB) was created with 4-24 RF applications in all but one patient. Special attention was paid to exclude incomplete block by meticulous mapping during pacing at the coronary sinus os and at the low lateral right atrium every 5 minutes for 20 minutes thereafter. Conduction recovered across the isthmus in 5 patients at 10, 10, 12, 15, and 16 minutes, respectively, and further RF applications were needed to obtain stable block. At a follow-up of 17 +/- 10 months, AFL occurred in the patient without, and in one patient with BDB. Thirty-three of the 34 patients (97%) with persistent BDB remained free of arrhythmia recurrence. This study showed that conduction resumed across the isthmus within 20 minutes, after AFL ablation in 15% of the patients. The long-term results of the procedure can be optimized by ascertaining the persistence of BDB during that period of time.

Adult↗
PubMed1985

[Study of atrial conduction tissue in the 17 mm V-C human embryo. Morphological contribution to the pathogenesis of sinoauricular node dysfunction].

Is there a specialised conduction pathway connecting the sinoatrial and atrioventricular nodes within the crista terminalis? As lesions of this zone can cause sinus node dysfunction and the sick-sinus syndrome, we decided to study this structure at the beginning of its embryonic development. Serial 10 micronthichness transverse sections of a 17 mm vertex-coccyx (Stage 19) human embryo were studied by light microscopy, anatomical reconstruction (Born) and morphometry. The region of the sinus venosus and venous valves, of the superior vena cava and the atrioventricular region were drawn and reconstructed with 150 X magnification by Born's method using wax plates of the following dimensions: 175 X 95X 1.5 mm. The volume of the region of the sino-atrial node was determined by multiplying the thickness of the sections by the surface of the region (measured by planimetry using the point counting method); its value was 15.4 X 10(6) microns3 with an antero-posterior diameter of 490,0 micron. These results show that this region is already proportionally larger in Stage 19 embryos. Reconstruction showed the sinoatrial node region to be a round bulge with a groove on either side: that of the sulcus terminalis and the superior vena cava on the left and the same vein with the mesocardium on the right. The right venous valve connects this zone with the interatrial septum and comprises two distinct cellular components, on derived from the atrial wall and the other from the muscle of the sinus venous. The artery fo the sinoatrial node was identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed2006

Extended atrial conduction system characterised by the expression of the HCN4 channel and connexin45.

OBJECTIVE: In the heart, there are multiple supraventricular pacemakers involved in normal pacemaking as well as arrhythmias and the objective was to determine the distribution of HCN4 (major isoform underlying the pacemaker current, I(f)) in the atria. METHODS: In the atria of the rat, the localisation of HCN4 and connexins was determined using immunohistochemistry, and electrical activity was recorded using extracellular electrodes. RESULTS: As expected, HCN4 and Cx45 (but not Cx43) were expressed in the sinoatrial node extending from the superior vena cava down the crista terminalis. The same pattern of expression of HCN4 and connexins was observed in a novel tract of nodal-like cells extending from the superior vena cava down the interatrial groove. Although the sinoatrial node was usually the leading pacemaker site, the novel tract of HCN4-expressing cells was capable of pacemaking and could act as the leading pacemaker site; there was evidence of a hierarchy of pacemakers. The same pattern of expression of HCN4 and connexins was also observed in the atrioventricular ring bundle (including the atrioventricular node) encircling the tricuspid valve, but not in the atrioventricular ring bundle encircling the mitral valve. HCN4 was not expressed in the pulmonary veins. CONCLUSIONS: The widespread distribution of HCN4 can explain the widespread location of the leading pacemaker site during sinus rhythm, the extensive region of tissue that has to be ablated to stop sinus rhythm, and the widespread distribution of ectopic foci responsible for atrial tachycardia.

Animals↗