Surgical technique and the mechanism of atrial tachycardia late after open heart surgery

INTRODUCTION

Diverse atrial tachycardias (ATs) can develop after open heart surgery. The aim of our study was to examine the determinants of the mechanism of postoperative AT.

METHODS AND RESULTS

One hundred patients with AT occurring at least 3 months after open heart surgery were studied. Patients were grouped according to the atrial incision applied at the time of surgery. During 127 electrophysiology procedures, 151 ATs were studied. Eighty-eight patients had cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL), 49 patients had at least one non-CTI-dependent AFL and 11 patients had focal AT. While CTI-dependent AFL was equally prevalent across groups, the finding of a non-CTI-dependent AFL was progressively more common as more extensive atriotomy was applied (p < 0.001). Among patients who had right atrial (RA) operations, RA incisional tachycardia was the most common non-CTI-dependent circuit, while the finding of perimitral or left atrial (LA) roof-dependent AFL was associated with LA atriotomy (p = 0.002 and p = 0.041, respectively). After adjustment for possible confounders, surgical group remained independent predictor of non-CTI-dependent AFLs (p < 0.001). No predictor was identified for focal AT, which originated from typical predilection sites and in 36% from the vicinity of surgical scar. Radiofrequency ablation was highly effective for all ATs, but the recurrence rate of AFL and atrial fibrillation was high at 22% and 27%, respectively, during 19 ± 15 months of follow-up.

CONCLUSION

While CTI-dependent AFL is the most common AT late after open heart surgery, atypical AFL becomes progressively more common with more extensive atriotomy. Right atrial incisional tachycardia is the dominant non-CTI-dependent AFL after opening of the RA, while a perimitral or roof-dependent LA circuit can be expected after LA operations.

A simple algorithm for defining the mechanism and the chamber of origin in atrial tachycardias

INTRODUCTION

Although macroreentrant atrial tachycardia (MRAT) and focal atrial tachycardia (FAT) can be successfully cured by catheter ablation, the proper diagnosis and treatment of these arrhythmias can still be challenging.

AIM

The objective of this study is to develop an algorithm allowing rapid diagnosis of the mechanism and the chamber of origin of atrial tachycardia based on intracardiac catheter recordings from the right atrium and the coronary sinus (CS).

METHODS

A 2-stepped algorithm was designed: (1) The time of biatrial activation expressed as a percentage of the tachycardia cycle length served to discriminate FAT from MRAT. (2) In FAT, the direction of activation of the CS catheter and the earliest atrial activation were used to define the chamber of origin. In MRAT, the time of right atrium activation was determined or entrainment was used at different sites. Thirty-two intracardiac recordings were reviewed off-line after the algorithm by 4 electrophysiologists blinded to the mechanism and the chamber of origin. The results of their analysis were compared with the intraoperative diagnosis.

RESULTS

The algorithm correctly identified 11 (100%) of 11 FATs and 19 (90.4%) of 21 MRATs. The site of origin was correctly identified in 8 (72.7%) of 11 FATs and in 20 of 21 (95.2%) MRATs. The site of origin was misidentified in 3 FATs, all arising from the CS ostium.

CONCLUSIONS

This algorithm allows rapid discrimination between FAT and MRAT. The chamber of origin is detected with a high accuracy in MRAT. However, the earliest atrial activation taken as an isolated event is not a good predictor for the chamber of origin in FAT arising from the ostium of the CS.

A post-ischaemic single administration of galanthamine, a cholinesterase inhibitor, improves learning ability in rats

Transient forebrain ischaemia is widely observed in clinical practice. We have examined the effect of a single administration of the cholinesterase inhibitor galanthamine (2mg kg(-1) i.p.) 25 min after reperfusion in male Sprague-Dawley rats (180 +/- 20 g) after a 20-min common carotid artery occlusion. Twenty-four-hours post-ischaemia there was no difference in motor co-ordination or muscle tonus of the rats treated with or without galanthamine as assessed by the rota-rod test. Learning ability was examined using the shuttle-box test, evaluating the latency time and the number of errors for six days in succession. The performance of the ischaemic saline-injected rats was significantly impaired on days 4, 5, 6 (latency time) compared with the non-ischaemic rats and with the ischaemic animals administered galanthamine (P < 0.05). Similar results were obtained when counting the number of errors (failure to cross the cage during conditioned or unconditioned stimulus). The monitoring of body temperature during the first 12-h post-ischaemia did not show any significant difference between the groups. The data showed a beneficial effect of galanthamine on the recovery of learning ability when administered once only post-ischaemia. This suggests a direct effect on the early pathologic mechanisms of CNS damage. Cholinesterase inhibitors may prove useful in the early clinical treatment of ischaemic conditions.