Radiofrequency catheter selection based on cavotricuspid angiography compared with a control group with an externally cooled-tip catheter: a randomized pilot study.

BACKGROUND: Radiofrequency ablation (RFA) of cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) can be performed using either externally cooled-tip RFA catheters or large-tip (8 mm) catheters. However, experimental and clinical studies suggest that the efficacy of both catheters may vary with CTI anatomy and catheters orientation. OBJECTIVES: The aim of this prospective study was to evaluate: a RFA catheter selection based on CTI angiography compared with a control group with an externally cooled-tip catheter together with the risk of an expensive crossover catheter in both groups. METHOD: Over a period of 16 months, 119 patients were included and randomized. RESULTS: When comparing the angiographic group (n = 56) and the externally cooled-tip RFA catheter group (n = 63), the duration of application time with a median of 7 min (interquartile range 4.5-11) versus a median of 10 min (interquartile range 6-20; P = 0.008) and the duration of X-ray exposure with a median of 7 min (interquartile range 4-10) versus a median of 10 min (interquartile range 5-15; P = 0.025) were significantly lower in the angiographic group versus externally cooled-tip catheter group. Furthermore, the number of catheters crossover was significantly higher in the angiographic group versus externally cooled-tip catheter group I (27% vs 7%; P = 0.007). CONCLUSIONS: This study shows that a strategy with a catheter selection based on a CTI angiographic evaluation is superior to an empirical use of an externally cooled-tip catheter during CTI RFA. Thus, angiographic isthmus evaluation predicts the effectiveness of a RFA catheter and the risk of an expensive catheter crossover.

Monitoring of ventilation during the early part of cardiopulmonary exercise testing: the first step to detect central sleep apnoea in chronic heart failure.

BACKGROUND AND PURPOSE: To evaluate the prediction of nocturnal central sleep apnoea (CSA) syndrome from the presence of periodic breathing (PB) on diurnal monitoring of pre-exercise (cardiopulmonary exercise test [CPX]) parameters. CSA syndrome is commonly found in congestive heart failure (CHF) patients and has several prognostic and therapeutic implications but is frequently undiagnosed. Awake PB pattern is sometimes observed during the CPX cardiopulmonary monitoring period of gas exchanges in CHF patients referred to the stress test laboratory for routine peak VO2 determination. PATIENTS AND METHODS: Forty-five consecutive ambulatory patients (2 women/43 men; 60.2+/-11.7 years old) with clinically moderate to severe CHF (New York Heart Association [NYHA] class II/III: 22/23; mean+/-standard deviation left ventricular ejection fraction [LVEF]: 30.5+/-6.6%) underwent a classical maximal CPX test including a 2-min period (pre-test) of gas exchange monitoring and nocturnal ambulatory polygraphic monitoring. PB was defined when a cyclical pattern of VE, VO2, VCO2, was visually noted during the pre-exercise period and/or during the first 4 min of the CPX. CSA syndrome was retained as a central apnoea-plus-hypopnea index (cAHI) equal to or more than 10/h. The sleep study scoring procedure was done independently of the knowledge of the CPX results. Sensitivity, specificity and predictive values were calculated and receiver operating characteristic (ROC) curve analysis was constructed. RESULTS: Peak VO2 reached 16.4+/-5.2 mL kg(-1)min(-1) (55% of the theoretical value adjusted for gender and age). The polygraphy was completed and validated (at least five consecutive hours of sleep) in all cases. CSA syndrome was found in 28 (62%) patients (mean cAHI: 19.3+/-8.6/h). Sensitivity for the prediction of CSA syndrome reached 92.9% (two false-negative patients with a cAHI of nine) and specificity 94.1% with a predictive accuracy of 93.3%. The only false-positive patient suffered a moderate but significant obstructive sleep apnoea syndrome. Using ROC curve analysis, the W value reached 0.99 for the prediction of CSA from the presence of PB. The presence of CSA syndrome, using logistic regression analysis, is associated with a more severe functional status (NYHA: p<0.01, peak VO2: p<0.002), a lower basal and peak end-expiratory CO2 pressure (PETCO2, all p<0.03), a worse LVEF (p<0.01) and age equal to or more than 60 years (p<0.03). CONCLUSIONS: The observation of PB in the preliminary period of the CPX test in CHF patients appeared highly predictive of the presence of CSA syndrome during sleep and could prompt the use of polygraphic monitoring in severe CHF patients.

Catheter selection for ablation of the cavotricuspid isthmus for treatment of typical atrial flutter.

Radiofrequency catheter ablation (RFA) represents the first line therapy of the cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) with a high efficacy and low secondary effects. RFA of CTI-dependent AFL can be performed by using various types of ablation catheters. Recent evaluations comparing externally cooled tip RFA (ecRFA) catheters and large-tip (8 mm) catheters have revealed that these catheters have a higher efficacy for CTI-AFL ablation compared to 4-mm catheters. The reliability of RFA catheters for AFL is variable and an optimal catheter selection may enhance the RFA effectiveness. The main goal of this article is to review the elements that improve the management of CTI RFA. Preliminary examinations of histopathologic and anatomical elements that may interfere with conventional CTI RFA are presented. Experimental studies concerning the electrobiology of large-tip and cooled-tip catheters are compared. The different catheter designs between cooled-tip and 8-mm-tip catheters are examined (size of the deflectable curve, rotation stability, and size of the distal nonsteerable catheter part) because of their critical role in CTI RFA results. A thorough review of clinical trials of each catheter is presented, and comparison of both catheters in this clinical setting is analyzed. In addition, the role of CTI morphology on AFL RF duration is underlined such as the value of right atrial angiography as an adjunct tool for CTI RFA catheter selection. Based on randomized studies, 8-mm-tip catheters seem to be more effective for ablation in case of straight angiographic isthmus morphology. On the other hand, ecRFA catheters appear to be more effective in cases of complex CTI anatomy or difficult CTI RFA. To reduce X-ray exposition and RFA application time, few studies report that CTI angiographic evaluation before RFA allows a catheter selection based on both CTI morphology and length. Moreover, preliminary data of randomized studies showed that an angiographic isthmus evaluation may predict both the effectiveness of a RFA catheter and the risk of an expensive catheter crossover.