Long-term follow-up and comparison of techniques in radiofrequency ablation of ventricular arrhythmias originating from the aortic cusps (AVATAR Registry)

Introduction: Radiofrequency ablation (RFA) of outflow tract ventricular arrhythmia (VA) that originates from the aortic cusps can be challenging. Data on long-term efficacy and safety as well as optimal technique after aortic cusp ablation have not previously been reported. Objectives: This aim of the study was to determine the short- and long-term outcomes after RFA of aortic cusp VA, and to evaluate aortic valve injuries according to echocardiographic screening. Patients and methods: This was a prospective multicenter registry (AVATAR, Aortic Cusp Ventricular Arrhythmias: Long Term Safety and Outcome from a Multicenter Prospective Ablation Registry) study. A total of 103 patients at a mean age of 56 years (34–64) from the “Electra” Registry (2005–2017) undergoing RFA of aortic cusps VA were enrolled. The following 3 ablation techniques were used: zero-fluoroscopy (ZF; electroanatomical mapping [EAM] without fluoroscopy), EAM with fluoroscopy, and conventional fluoroscopy-based RFA. Data on clinical history, complications after RFA, echocardiography, and 24-hour Holter monitoring were collected. The follow-up was 12 months or longer. Results: There were no major acute cardiac complications after RFA. In one case, a vascular access complication required surgery. The median (interquartile range [IQR]) procedure time was 75 minutes (IQR, 58–95), median follow-up, 32 months (IQR, 12–70). Acute and long-term procedural success rates were 93% and 86%, respectively. The long-term RFA outcomes were observed in ZF technique (88%), EAM with fluoroscopy (86%), and conventional RFA (82%), without differences. During long-term follow-up, no abnormalities were found within the aortic root. Conclusions: Ablation of VA within the aortic cusps is safe and effective in long-term follow-up. The ZF approach is feasible, although it requires greater expertise and more imaging modalities

Effects of slow deep breathing at high altitude on oxygen saturation, pulmonary and systemic hemodynamics

Slow deep breathing improves blood oxygenation (SpO2) and affects hemodynamics in hypoxic patients. We investigated the ventilatory and hemodynamic effects of slow deep breathing in normal subjects at high altitude. We collected data in healthy lowlanders staying either at 4559 m for 2-3 days (Study A; N = 39) or at 5400 m for 12-16 days (Study B; N = 28). Study variables, including SpO2 and systemic and pulmonary arterial pressure, were assessed before, during and after 15 minutes of breathing at 6 breaths/min. At the end of slow breathing, an increase in SpO2 (Study A: from 80.2\ub17.7% to 89.5\ub18.2%; Study B: from 81.0\ub14.2% to 88.6\ub14.5; both p<0.001) and significant reductions in systemic and pulmonary arterial pressure occurred. This was associated with increased tidal volume and no changes in minute ventilation or pulmonary CO diffusion. Slow deep breathing improves ventilation efficiency for oxygen as shown by blood oxygenation increase, and it reduces systemic and pulmonary blood pressure at high altitude but does not change pulmonary gas diffusion

Disappearance of isocapnic buffering period during increasing work rate exercise at high altitude

BACKGROUND: At sea level, ventilation kinetics are characterized during a ramp exercise by three progressively steeper slopes, the first from the beginning of exercise to anaerobic threshold, the second from anaerobic threshold to respiratory compensation point, and the third from respiratory compensation point to peak exercise. In the second ventilation phase, body CO2 stores are used to buffer acidosis owing to lactate production; it has been suggested that this extra CO2 production drives the ventilation increase. At high altitude, ventilation increases owing to hypoxia. We hypothesize that ventilation increase reduces body CO2 stores affecting ventilation kinetics during exercise. DESIGN: In eight healthy participants, we studied the ventilation kinetics during an exercise performed at sea level and at high altitude (4559 m). METHODS: We used 30 W/2 min step incremental protocol both at sea level and high altitude. Tests were done on a cyclo-ergometer with breath-by-breath ventilation and inspiratory and expiratory gas measurements. We evaluated cardiopulmonary data at anaerobic threshold, respiratory compensation point, peak exercise and the VE/VCO2 slope. RESULTS: At high altitude: (a) peak VO2 decreased from 2595\ub1705 to 1745\ub1545 ml/min (P<0.001); (b) efficiency of ventilation decreased (VE/VCO2 slope from 25\ub12 to 38\ub14, P<0.0001); (c) at each exercise step end-tidal pressure change for CO2 was lower; and (d) the isocapnic buffering period disappeared in seven over eight participants and was significantly shortened in the remaining participant. CONCLUSION: Exercise performed at high altitude is characterized by two, instead of three, ventilation slopes