Direct current ablation

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

FIGURE 6-1. Algorithm for the treatment of atrial fibrillation (AF) and atrial flutter. °lf AF <48 hours, anticoagulation prior to cardioversion is unnecessary may consider transesophageal echocardiogram (TEE) if patient has risk factors for stroke. Ablation may be considered for patients who fail or do not tolerate one antiarrhythmic drug (AAD). Chronic antithrombotic therapy should be considered in all patients with AF and risk factors for stroke regardless of whether or not they remain in sinus rhythm. (BB, 8-blocker CCB, calcium channel blocker p.e., verapamil or diltiazem] DCC, direct-current cardioversion.)... 

A number of creative ways have been developed to create nonuniformities in an electric field using insulators. Initial efforts simply used prefabricated posts embedded in the channels [6] or rectangular [8], triangular [3], oil menisci [9], and other protrusions into the channels. The most common insulator materials are polymers utilized for photolithography or hot press microfahrication including polydimethylsiloxane PDMS and polymethyl methacrylate PMMA, or glass or silicone, which can be chemically etched or ablated [2]. A key attribute of direct current dielectrophoresis is that the electrodes supplying the electric field can be located more remotely on the lab-on-a-chip device. Electrodes can be immersed in fluid in chambers at either end of the test channel to avoid detrimental electrolysis reaction products [31]. Please see Pig. 1. 

Hz in repetition rate), after increasing a direct-current electric field applied between the parallel Cu plates of electrodes, stable PLASLA is formed at an electric field of 400 V, which is inadequate to form DC-plasma (direct current plasma), which is formed by the direct discharge at a potential of 500 V without laser ablation. The oscilloscope trace of PLASLA luminescence signal in Fig. 1(b) indicates that plasma is formed by the first laser ablation, quenched by the next ablation, formed again by the third ablation, quenched again by the fourth ablation, and so on, indicating that the PLASLA formation and quenching completely synchronize with laser ablation. 

For the ultrasound ablation two methods are currently available - extracorporeal (transcutaneous) and direct (or percutaneous) via a needle-like applicator. The term high intensity focused ultrasound should be reserved for describing the extracorporeal method. Direct ultrasound ablation means the replacement of an applicator via a percutaneous or laparoscopic insertion. 

Mitchell et al. [80] have described development of a laser ablation/direct-current argon plasma (DCP) emission spectrometry system based on a relatively low-energy, high-repetition rate Nd YAG laser as opposed to the high-energy and low-repetition rate ruby lasers. 

Zhou L, et al, Thromboembolic complications of cardiac radiofrequency catheter ablation a review of the reported incidence, pathogenesis and current research directions. J Cardiovasc Electrophysiol 1999 10(4) 61 I —620. 

---