Proposing national diagnostic reference levels for electrophysiology studies and catheter ablation procedures in Bulgaria.

INTRODUCTION: The implementation of diagnostic reference levels (DRLs) is an essential tool for optimisation of the routine practice, better management of patient exposure while maintaining sufficient image quality. National DRLs for electrophysiology (EP) procedures are not available in our country. PURPOSE: The main purpose of the study was to propose, for first time in Bulgaria, national DRLs (NDRLs) for EP studies and ablation procedures of two different levels of complexity. The proposed DRLs can be later used to establish NDRLs by the national authority with regulatory functions related to medical exposure. METHOD: A retrospective study was done with the three highest volume Bulgarian EP centers, where over 95% of all cardiac ablations were performed. Data were extracted from the electronic registry for invasive electrophysiology BG-EPHY. Independently of the proposed NDRLs, we also compared the air kerma-area product (KAP) between the participating centers for procedures of the same level of complexity. RESULTS: The proposed NDRL in terms of KAP were: 5.2 Gy.cm2 for diagnostic EP studies, 25.5 Gy.cm2 for simple ablations, and 52.1 Gy.cm2 for complex ablations. There was a significant variation in KAP for procedures with the same degree of complexity within each center. CONCLUSION: This study is the first to propose NDLRs for EP studies and ablation procedures of two levels of complexity in Bulgaria. The results identified EP procedures requiring further optimization of patient protection and provided a basis for future comparisons and standardization with further investigations on the topic. The proposed NDRLs are recommended to be used for better management of radiation exposure during EP procedures of different levels of complexity.

Catheter Ablation of Idiopathic Ventricular Arrhythmias Originating from the Para-Hisian area - QRS Morphology Change and Late Effect of the Ablation: Case Series.

INTRODUCTION: Radiofrequency catheter ablation of idiopathic ventricular arrhythmias originating in the para-Hisian region could be challenging because of a potential risk of iatrogenic atrioventricular block. Uncommonly, shift of the exit site during the ablation can be observed. Consequently, different approaches of radiofrequency catheter ablation of para-Hisian ventricular foci can be needed. CASE SERIES PRESENTATION: Three patients (2 males) underwent electroanatomical mapping and catheter ablation for idiopathic premature ventricular contractions originating near the His bundle. Patients underwent 24-h ECG Holter monitoring during follow-up. All patients had premature ventricular contractions with left bundle branch block morphology and inferior or horizontal axis. However, change of QRS morphology during ablation was observed, due to a change in the exit site. In two patients there was reduction of the arrhythmia burden after initially unsuccessful procedure. Mapping and ablation in the aortic root were needed in one patient. There were no complications. DISCUSSION: Radiofrequency catheter ablation of para-Hisian ventricular arrhythmias is feasible and safe when performed cautiously. A change in the premature ventricular contractions' morphology and exit site during ablation may ensue; therefore, extensive mapping on both sides of the interventricular septum as well as in the aortic root may be warranted.

Correlation between the sudden jump-like increases of the atrio-Hisian interval induced during burst atrial pacing and during programmed atrial stimulation in patients with atrioventricular nodal reentrant tachycardia.

PURPOSE: To study the correlation between the sudden prolongations of the atrio-Hisian (AH) interval with ≥50 ms during burst and programmed atrial stimulation, and to define whether the AH jump during burst atrial pacing is a reliable diagnostic criterion for dual AV nodal physiology. METHODS: Retrospective data on 304 patients with preliminary ECG diagnosis of AV nodal reentrant tachycardia (AVNRT), confirmed during electrophysiological study, was analyzed for the presence of AH jump during burst and programmed atrial stimulation, and for correlation between the pacing modes for inducing the jump. Wilcoxon signed-ranks test and Spearman's bivariate correlation coefficient were applied, significant was P-value <0.05. RESULTS: The population was aged 48.5 ± 15.7 (12-85) years; males were 38.5%. AH jump occurred during burst atrial pacing in 81% of the patients, and during programmed stimulation - in 78%, P = 0.366. In 63.2% AH jump was induced by both pacing modes; in 17.8% - only by burst pacing; in 14.8% - only by programmed pacing; in 4.2% there was no inducible jump. There was negative correlation between both pacing modes, ρ = -0.204, Р<0.001. CONCLUSION: Burst and programmed atrial stimulation separately prove the presence of dual AV nodal physiology in 81 and 78% of the patients with AVNRT, respectively. There is negative correlation between the two pacing modes, allowing the combination of the two methods to prove diagnostic in 95.8% of the patients.

Unusual site of origin of a non-automatic focal right ventricular tachycardia.

Focal right ventricular tachycardia is relatively uncommon. It usually arises from specific anatomic locations. A 59-year-old woman with a structurally normal heart and an automatic cardioverter-defibrillator implanted beforehand presented with drug-resistant incessant ventricular tachycardia for which 1786 anti-tachycardia pacing therapies and 119 shocks had been delivered. Electroanatomical mapping showed focal tachycardia originating from the acute margin of the right ventricle. Irrigated catheter ablation was performed successfully.

Selective slow pathway ablation using transseptal approach in a patient with surgically corrected partial atrioventricular canal defect and atrioventricular nodal reentrant tachycardia of the common type.

A 26-year-old woman with partial atrioventricular (AV) canal defect surgically closed with pericardial patch in a mode that the triangle of Koch had become part of the left atrium underwent successful slow pathway ablation for slow-fast AV nodal reentrant tachycardia. Transseptal approach was used because of the atypical post-operative anatomy. Transseptal catheter ablation of the slow pathway can be a reasonable and safe alternative in patients subjected to this type of operation.

Percutaneous coronary intervention for acute myocardial infarction in a single coronary artery anomaly.

We report on a case of an adult male patient with previously unknown coronary anomaly and acute myocardial infarction in the territory of the left anterior descending artery (LAD). The coronary angiography showed a single coronary artery with intertruncal course, arising from the right coronary sinus, and thrombotic occlusion of the LAD. Successful transradial percutaneous coronary intervention was done with implantation of an intracoronary stent in the occluded artery. The postprocedural course was complicated by ventricular tachycardia, congestive heart failure, and mild transient renal failure. In conclusion, transradial percutaneous coronary intervention is safe and feasible in rare coronary artery anomalies even in an emergent setting. The finding of an anomalous coronary artery should not be a reason to decline performing coronary intervention.

Bi-atrial and right atrial activation times help to differentiate focal from macroreentrant right atrial tachycardias.

OBJECTIVE: The objective was to study atrial activation intervals and their relation to the tachycardia cycle length (TCL) as electrophysiologic parameters differentiating focal (FAT) from macroreentrant atrial tachycardias (MRAT) originating in the right atrium. METHODS: In 21 patients (8 men) with 30 successfully ablated right atrial tachycardias (15 focal) the endocardial activity during tachycardia was registered using multipolar catheters in the right atrium and the coronary sinus. Using this catheter configuration we measured the tachycardia cycle length (TCL), biatrial activation (BAA), right atrial activation (RAA), left atrial activation (LAA), as well as the proportion of those intervals to TCL. In 14 patients, the measurements were repeated in sinus rhythm as well. The diagnostic accuracy of the ratio of BAA to TCL was assessed. RESULTS: TCL was longer, but all other intervals and ratios were significantly shorter in FAT compared to MRAT (P < 0.05 for all parameters, except for LAA - P = NS). During sinus rhythm, patients with MRAT had prolonged RAA (P = 0.003), but not BAA and LAA (P = NS), compared to patients with FAT. A discriminating value of 40% for the ratio of BAA to TCL, compared to 50% and 30%, was found to have the best sensitivity, specificity, positive and negative predictive values for MRAT, as well as for FAT. CONCLUSIONS: BAA, RAA, LAA and their relation to the TCL are significantly shorter in FATs compared to MRATs arising from the right atrium. The ratio of BAA to TCL obtained using a simple 2-catheter configuration, allows a rapid and reliable differentiation between FAT and MRAT.

Acceso transeptal a la aurícula izquierda desde la vena femoral izquierda / Transseptal access to the left atrium from the left femoral vein

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Radiofrequency catheter ablation in a child with Wolff-Parkinson-White syndrome and congenitally corrected transposition of the great arteries.

The case is presented of a five-year-old boy with Wolff-Parkinson-White syndrome, who had undergone three surgical palliations because of congenitally corrected transposition of the great arteries, ventricular septal defect and pulmonary trunk near-atresia. Successful and uncomplicated radiofrequency catheter ablation of an accessory pathway located across the systemic atrioventricular valve ring was performed. The procedure was motivated by forthcoming corrective surgery, which would preclude venous access to the heart. This case emphasizes the need for precise timing of ablative therapy in such patients and shows that surgery itself may facilitate catheter ablation. (Cardiol J 2007; 14: 500-503).