Intra-atrial Conduction Block During Radiofrequency Ablation of Left-sided Accessory Pathways.

Catheter ablation is currently the therapeutic approach of choice for many patients with accessory pathways. Despite the high success rate of radiofrequency ablation of the left lateral accessory pathways, a rather uncommon manifestation is intra-atrial conduction block at the level of the mitral isthmus. We report 2 cases of orthodromic atrioventricular reentrant tachycardia using a concealed left-sided accessory pathway with an abrupt change in the activation of the coronary sinus from an eccentric to concentric sequence after ablation delivery. The electrophysiological characteristics and the underlying mechanism of the intra-atrial conduction block are commented on. Careful mapping and assessment of relative conduction are helpful to document the diagnosis of intra-atrial conduction block. Familiarity with the likelihood of intra-atrial block during left lateral accessory pathway ablation is needed to avoid the erroneous elucidation that a second accessory pathway is present and to identify correctly the ablation site of interest.

Left atrial voltage mapping using a new impedance-based algorithm in patients with paroxysmal atrial fibrillation.

AIMS: Atrial fibrosis is associated with the pathogenesis and progression of atrial fibrillation (AF). We sought to evaluate the extent of left atrial (LA) scarring in patients with paroxysmal AF (PAF) undergoing catheter ablation using a new impedance-based algorithm. METHODS: We prospectively enrolled 73 consecutive patients (43 males, 58 years) with PAF who underwent pulmonary vein antral isolation. We first performed high-density bipolar voltage mapping during sinus rhythm using Tissue Proximity Indicator (TPI), one of the features of the ConfiDense mapping module integrated in the electroanatomic mapping system. A dense LA shell was created initially without TPI (mean points 2,411) and subsequently activating TPI (mean points 1,167). Each point was classified according to the peak-to-peak bipolar voltage electrogram based on two criteria (criterion A: healthy >0.8 mV, border zone: 0.4-0.8 mV, scarred: <0.4 mV; criterion B: healthy: >0.5 mV, border zone: 0.25-0.5 mV, scarred: <0.25 mV). RESULTS: LA voltage analysis represented significantly smaller scarred areas when mapping was performed with TPI-ON compared with TPI-OFF in both voltage criteria (average LA voltage area: 3.02 ± 5.28 cm2 vs 9.15 ± 13.11 cm2 vs in criterion A and 1.19 ± 2.54 cm2 vs 5.61 ± 9.56 cm2 in criterion B). A statistically significant voltage difference was observed in all segments of the left atrium between the two mapping protocols, particularly on the inferior wall. CONCLUSION: A more specific delineation of LA fibrosis may be produced using the TPI feature of the ConfiDense mapping module, through elimination of false-positive annotated mapping points due to low contact.

High risk electrocardiographic markers in Brugada syndrome.

Several clinical, electrocardiographic (ECG) and electrophysiological markers have been proposed to provide optimal risk stratification in patients with Brugada syndrome (BrS). Of the different markers, only a spontaneous type 1 ECG pattern has clearly shown a sufficiently high predictive value. This review article highlights specific ECG markers based on depolarization and/or repolarization that have been associated with an increased risk of arrhythmic events in patients with BrS.

Use of Ventilator Bundle and Staff Education to Decrease Ventilator-Associated Pneumonia in Intensive Care Patients.

BACKGROUND: Ventilator-associated pneumonia (VAP), one of the most common hospital-acquired infections, has a high mortality rate. OBJECTIVES: To evaluate the incidence of VAP in a multidisciplinary intensive care unit and to examine the effects of the implementation of ventilator bundles and staff education on its incidence. METHODS: A 24-month-long before/after study was conducted, divided into baseline, intervention, and postintervention periods. VAP incidence and rate, the microbiological profile, duration of mechanical ventilation, and length of stay in the intensive care unit were recorded and compared between the periods. RESULTS: Of 1097 patients evaluated, 362 met the inclusion criteria. The baseline VAP rate was 21.6 per 1000 ventilator days. During the postintervention period, it decreased to 11.6 per 1000 ventilator days (P = .01). Length of stay in the intensive care unit decreased from 36 to 27 days (P = .04), and duration of mechanical ventilation decreased from 26 to 21 days (P = .06). CONCLUSIONS: VAP incidence was high in a general intensive care unit in a Greek hospital. However, implementation of a ventilator bundle and staff education has decreased both VAP incidence and length of stay in the unit.

Carboxyhemoglobin and methemoglobin levels as prognostic markers in acute pulmonary embolism.

OBJECTIVES: Carboxyhemoglobin (COHb) and methemoglobin (MetHb) levels have been associated with a poor outcome in patients with various pathological conditions including cardiovascular diseases. Our aim was to retrospectively assess the prognostic value of arterial COHb and MetHb in patients with acute pulmonary embolism (PE). METHODS: We conducted a retrospective study of 156 patients admitted in a pulmonary clinic due to acute PE. Measured variables during emergency department evaluation that were retrospectively analyzed included the ratio of the partial pressure of oxygen in arterial blood to the fraction of oxygen in inspired gas, Acute Physiology and Chronic Health Evaluation II score, risk stratification indices, and arterial blood gases. The association between arterial COHb and MetHb levels and disease severity or mortality was evaluated using bivariate tests and logistic regression analysis. RESULTS: Arterial COHb and MetHb levels correlated with Acute Physiology and Chronic Health Evaluation II and pulmonary severity index scores. Furthermore, arterial COHb and MetHb levels were associated with troponin T and N-terminal pro-B-type natriuretic peptide levels. In univariate logistic regression analysis, COHb and MetHb levels were both significantly associated with an increased risk of death. However, in multivariate analysis, only COHb remained significant as an independent predictor of in-hospital mortality. CONCLUSION: Our preliminary data suggest that arterial COHb and MetHb levels reflect the severity of acute PE, whereas COHb levels are independent predictors of in hospital death in patients in this clinical setting. These findings require further prospective validation.