Manfred Marx

Cold water submersion and cardiac arrest in treatment of severe hypothermia with cardiopulmonary bypass

In the paediatric population, submersion injury with drowning or near-drowning represents a significant cause of morbidity and mortality. This study reviews retrospectively our own experiences and the literature on the use of cardiopulmonary bypass (CPB) to rewarm paediatric victims of cold water submersion who suffer severe hypothermia (<28 degrees C) and cardiac arrest (asystole or ventricular fibrillation). In addition to three children treated at our institution, nine other victims were found in the literature. In this cohort of 12 children aged between 2 and 12 years, there was a tendency to better outcome with lower core temperature at the beginning of extracorporeal circulation (mean temperature in nine survivors, 20 degrees C; in three non-survivors, 25.5 degrees C). The lowest temperature survived was 16 degrees C. Neither base excess, pH nor serum potassium levels were reliable prognostic factors. The lowest base excess in a survivor was -36.5 mmol/l, the lowest pH 6.29. We consider CPB as the method of choice for resuscitation and rewarming of children with severe accidental hypothermia and cardiac arrest (asystole or ventricular fibrillation). Compared with adults, children, especially smaller ones, require special consideration with regard to intravenous cannulation as drainage can be inadequate using femoral-femoral cannulation. In hypothermic children we advocate, therefore, emergency median sternotomy. Until more information regarding prognostic factors are available, children who are severely hypothermic and clinically dead after submersion in cold water--even if for an unknown length of time--should receive cardiopulmonary resuscitation (CPR) and be transported without delay to a facility with capabilities for CPB instituted via a median sternotomy.

Frequency of Recurrence of Atrial Fibrillation Within 48 Hours After Ablation and Its Impact on Long-Term Outcome

Because of delayed structural and electrophysiologic effects of radiofrequency ablation of atrial fibrillation (AF), early recurrence of AF after ablation does not necessarily indicate long-term ablation failure. This study was intended to assess the prognostic value of early recurrence of AF within 48 hours after ablation. The study included 234 patients (aged 23 to 80 years; 72% men) with symptomatic drug-resistant paroxysmal (n = 165) or persistent AF (n = 69) who underwent either Lasso-guided segmental pulmonary vein isolation (n = 83) or CARTO-guided left atrial circumferential ablation (n = 151). After a median follow-up of 12.7 months, 64% of patients with paroxysmal and 45% of patients with persistent AF were AF free. Early recurrence of AF occurred in 43% of patients and was more frequently observed in the persistent-AF group (paroxysmal vs persistent 39% vs 54%; p = 0.037). Early recurrence of AF was a significant predictor of long-term ablation failure in univariate (hazard ratio [HR] 2.29, p <0.001) and multivariate (HR 2.17. p <0.001) Cox regression analysis. Nevertheless, 46% of patients with early recurrence of AF were AF free during long-term follow-up compared with 68% of patients without early recurrence of AF. The prognostic value of early recurrence of AF was found in patients with paroxysmal (HR 2.05, p = 0.005) and persistent AF (HR 2.35, p = 0.013). In conclusion, early recurrence of AF within 48 hours after ablation was a significant predictor of a poor long-term ablation outcome. However, because nearly half the patients with early recurrence of AF remained AF free during long-term follow-up, early recurrence of AF should not automatically result in an early repeated procedure.

Time course of markers of tissue repair after ablation of atrial fibrillation and their relation to left atrial structural changes and clinical ablation outcome

BACKGROUND Radiofrequency ablation of atrial fibrillation (AF) creates left atrial (LA) tissue damage with a subsequent healing process. We sought to prospectively assess the time course of biomarkers of tissue repair after ablation and to evaluate their association with clinical variables. METHODS 30 consecutive patients (57.9 ± 1.7 yrs, 63% males) with paroxysmal AF underwent a CARTO-guided LA circumferential ablation, Lasso-guided segmental pulmonary vein isolation and ablation of complex fractionated atrial electrograms. Matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1), both key regulators of tissue repair, and the aminoterminal propeptide of type III procollagen (PIIINP), reflecting collagen synthesis, were determined in blood samples before and 6h, 1, 2, 7, 30, 90 and 180 days post-ablation. RESULTS All markers showed a significant ablation-induced up-regulation (MMP-9: 1.8 ± 0.1-fold, TGF-β1: 2.4 ± 0.4-fold, PIIINP: 1.3 ± 0.1-fold). MMP-9 was significantly up-regulated until day 90, TGF-β1 only on day 2. PIIINP increased from day 2 to 7. The area under the curve (AUC) of MMP-9 and TGF-β1 correlated with the ablation-induced reduction of LA volume (both p<0.05). The AUC of MMP-9 was additionally associated with the amount of radiofrequency energy delivered during ablation (p < 0.05). At 12 months of follow-up 57% of patients were free of AF off antiarrhythmic drugs. The AUC of PIIINP independently predicted recurrent AF (p < 0.05). CONCLUSIONS Markers of healing showed a significant up-regulation after AF ablation detectable for up to 90 days. A more pronounced up-regulation of MMP-9 or TGF-β1 is associated with a greater reduction of LA size. High PIIINP levels after ablation predict a poor ablation outcome.

Tako‐tsubo Cardiomyopathy Complicating Left Atrial Radiofrequency Ablation

Two female patients undergoing left atrial radiofrequency catheter ablation developed Tako‐tsubo cardiomyopathy. This reversible form of left ventricular dysfunction is known to occur under conditions associated with marked sympathetic nervous activation. Radiofrequency catheter ablation in the left atrium can damage autonomic ganglionated plexi, leading to vagal withdrawal, thus resulting in enhanced sympathetic tone. Tako‐tsubo cardiomyopathy has not been previously described following radiofrequency catheter ablation.

Combined circular multielectrode catheter and point-by-point ablation is superior to point-by-point ablation alone in eliminating atrial fibrillation

BACKGROUND Besides conventional point-by-point ablation, novel multielectrode catheters emerge for ablation of atrial fibrillation (AF). We sought to evaluate the clinical utility of a pulmonary vein (PV) isolation approach combining the advantages of both technologies. METHODS The study included 240 consecutive AF patients (60±11 years, 68% males, 62% paroxysmal). In the combined ablation group (n=120), PV isolation was performed with a circular multielectrode catheter (PVAC, Medtronic Ablation Frontiers) and completed by conventional point-by-point ablation (NaviStar ThermoCool Catheter, Lasso/CARTO technology, Biosense Webster). In the point-by-point ablation group (n=120), PV isolation was performed with point-by-point ablation alone. RESULTS Complete 1-year ablation success (freedom from any atrial arrhythmia off antiarrhythmic drugs) was more frequently observed in the combined ablation group (58.0% versus 43.3%, hazard ratio 1.72, 95% confidence interval 1.19-2.48, p=0.004). Also clinical success (≥90% reduction of arrhythmia burden on/off antiarrhythmic drugs) was significantly associated with the combined ablation approach (p=0.001). These associations remained significant after multivariable adjustment (both p≤0.005) and were not dependent on the type of AF. The rate of major adverse events (3.3% versus 2.5%) and the procedure time did not differ between groups. The fluoroscopy time, however, was significantly shorter in the combined ablation group (p<0.001) reflecting the reduced need for radiation during multielectrode catheter ablation. CONCLUSIONS A combined PV isolation approach based on multielectrode catheter ablation and complementary point-by-point ablation is superior to point-by-point ablation alone and reveals to be safe. A potential explanation for these findings is the improved durability of ablation lesion after the combined ablation approach.

Radiofrequency catheter ablation can be performed with high success rates and very low complication rates in children and adolescents

Radiofrequency catheter ablation is a standard treatment for tachyarrhythmia in children. Recently, several centres using cryoenergy for ablation have reported high success and low complication rates, but an increased risk of recurrence of arrhythmia. The aim of this study was to report success, complications and recurrence rates for radiofrequency catheter ablation in children under current conditions.