Intracardiac ultrasound detection of thrombus on transseptal sheath: incidence, treatment, and prevention.

BACKGROUND

Transseptal (TS) catheterization is used for left atrial (LA) ablation procedures and a major risk is thromboembolism. The purpose of this study was to assess (1) the value of intracardiac ultrasound (ICUS) monitoring during LA ablation procedures, and (2) a new technique to reduce the risk of thrombus formation.

METHODS AND RESULTS

One hundred and eighty consecutive patients underwent TS catheterization under ICUS guidance with two sheaths for atrial fibrillation ablation and one for other LA procedures. Group I included the initial 90 patients in whom TS sheaths were flushed with a standard 2 U/cc concentration of heparin; group II consisted of the next 90 patients in whom sheaths were flushed with 1,000 U/cc concentration. All patients received bolus and infusion of heparin to maintain ACT between 250-300 seconds. ICUS was monitored throughout. In group I, echodense material at the tip of the sheath consistent with thrombus was observed on ICUS in 8 of 90 patients (9%) within 5-15 minutes of entering the LA. In group II, only 1 of 90 patient (1%) demonstrated thrombus (P < 0.001). There were no significant clinical differences in group I patients with and without thrombus. In all nine patients, the clot was removed with vigorous aspiration. No patients suffered a neurological event.

CONCLUSION

Thrombus formation on TS sheath, detected by ICUS, may be more common than expected despite adequate anticoagulation. Using a higher concentration of heparin for the TS system before deployment reduced the risk. The thrombus was retrieved with aspiration without the need to abort the procedure.