The aim of this preliminary study was to evaluate the accuracy of left and right ventricular output computed from a semi-automatic processing of tomographic radionuclide ventriculography data (TRVG) in comparison with the conventional thermodilution method. Twenty patients with various heart diseases were prospectively included in the study. Thermodilution and TRVG acquisitions were carried out on the same day for all patients. Analysis of gated blood pool slices was performed using a watershed-based segmentation algorithm. Right and left ventricular output measured by TRVG correlated well with the measurements obtained with thermodilution (r = 0.94 and 0.91 with SEE = 0.38 and 0.46 l/min, respectively, P < 0.001). The limits of agreement for TRVG and thermodilution measurements were -0.78-1.20 l/min for the left ventricle and -0.34-1.16 l/min for the right ventricle. No significant difference was found between the results of TRVG and thermodilution with respect to left ventricular output (P = 0.09). A small but significant difference was found between right ventricular output measured by TRVG and both left ventricular output measured by TRVG (mean difference = 0.17 l/min, P = 0.04) and thermodilution-derived cardiac output (mean difference = 0.41 l/min, P = 0.0001). It is concluded that the watershed-based semi-automatic segmentation of TRVG slices provides non-invasive measurements of right and left ventricular output and stroke volumes at equilibrium, in routine clinical settings. Further studies are necessary to check whether the accuracy of these measurements is good enough to permit correct assessment of intracardiac shunts.

No abstract

Objectives: Complete bidirectional cavo-tricuspid isthmus (CTI) block is mandatory for radio-frequency (RF) ablation of typical atrial flutter (AF). CTI block can be assessed by a simplified method using two catheters and the technique of differential pacing, but long-term results in large series are poorly known. Methods: CTI RF ablation was performed in 255 consecutive patients with typical AF, using one quadripolar catheter, and the ablation catheter, in association with the technique of differential pacing. Results: Procedural success, as defined by documentation of complete bidirectional CTI block using limited activation mapping, positive differential pacing together with termination of ongoing AF, was achieved in 80% of patients. AF recurred in 37 patients (14%) over a mean follow-up period of 15 ± 9 months. Two hundred and forty-one patients (94%) were finally cured, with 1.1 procedures/patient. The recurrence rate was related to the achievement of complete CTI bidirectional block (12% vs. 29%, p = 0.01). Conclusions: Long-term results of CTI ablation, employing a simplified method using the differential pacing technique, are similar to those for the standard methods using multipolar catheters. Therefore, this technique compares favorably to other established methods for such common RF procedures, especially due to its lower cost.

No abstract