Abstract: BACKGROUND: This study of a chronic porcine postinfarction model examined whether linear epicardial cryoablation was capable of creating large, homogenous lesions in regions of the myocardium including scarred ventricle. Endocardial and epicardial focal cryolesions were also compared to determine if there were significant differences in lesion characteristics. METHODS: Eighty focal endocardial and 28 focal epicardial cryoapplications were delivered to eight normal caprine and four normal porcine ventricular myocardium, and 21 linear cryolesions were applied along the border of infarcted epicardial tissue in a chronic porcine infarct model in six swines. RESULTS: Focal endocardial cryolesions in normal animals measured 9.7+/-0.4 mm (length) by 7.3+/-1.4 mm (width) by 4.8+/-0.2 mm (depth), while epicardial lesions measured 10.2+/-1.4 mm (length) by 7.7+/-2 mm (width) by 4.6+/-0.9 mm (depth); P > 0.05. Linear epicardial cryolesions in the chronic porcine infarct model measured 36.5+/-7.8 mm (length) by 8.2+/-1.3 mm (width) by 6.0+/-1.2 mm (depth). The mean depth of linear cryolesions applied to the border of the infarct scar was 7+/-0.7 mm, as measured by magnetic resonance imaging. CONCLUSIONS: Cryoablation can create deep lesions when delivered to the ventricular epicardium. Endocardial and epicardial cryolesions created by a focal cryoablation catheter are similar in size and depth. The ability to rapidly create deep linear cryolesions may prove to be beneficial in substrate-based catheter ablation of ventricular arrhythmias.

Abstract: INTRODUCTION: The use of preprocedural CT or MR imaging to generate patient-specific cardiac anatomy greatly facilitates catheter ablation of the left atrium and pulmonary veins (LA-PVs) to treat atrial fibrillation (AF). This report details the accuracy and utility of an intraprocedural means to generate 3-D volumetric renderings of the LA-PV anatomy: contrast-enhanced rotational X-ray angiography (3DRA). METHODS AND RESULTS: Preprocedural CT or MR imaging and intraprocedural rotational angiography was performed in 42 patients undergoing AF ablation procedures. Initially, pulmonary artery (PA) bolus-chase contrast injections were performed (20 mL, 20 mL/s) to establish pulmonary transit time and cardiac isocentering. Depending on cardiac size, either a single PA injection (80-100 mL, 20 mL/s) or two separate dedicated left/right PA branch injections were performed (60 mL each, 20 mL/s). For the latter, the two volumes of the left/right portions of the LA-PVs were registered and fused. LA-PV 3DRA images were assessed qualitatively and quantitatively in comparison with CT/MR images. The majority of the 3DRA acquisitions (71%) were deemed at least "useful" in delineating the LA-PV anatomy. The LA appendage was delineated in 57% of the cases. A blinded quantitative comparison of PV ostial diameters resulted in an absolute difference of only 2.7 +/- 2.3 mm, 2.2 +/- 1.8 mm, 2.4 +/- 2.2 mm, and 2.2 +/- 2.3 mm for the left-superior, left-inferior, right-superior, and right-inferior PVs, respectively. The feasibility for registering the 3DRA image with real-time electroanatomical mapping was also demonstrated. CONCLUSION: Intraprocedural contrast-enhanced rotational angiography provides volumetric 3-D images of the LA-PVs of comparable diagnostic value to dedicated preprocedural CT/MR imaging.

Abstract: BACKGROUND: The presence and extent of contraction within the pulmonary veins (PVs) have not been defined clearly. OBJECTIVE: The purpose of this study was to determine whether PV contraction exists and can be visualized using multislice computed tomography (MSCT) scanning as this may indicate that this modality may be useful for monitoring patients after PV isolation procedures. METHODS: Analysis was performed on 29 patients (mean age 57.5 +/- 12 years) undergoing MSCT for suspected coronary artery disease without structural heart disease or left atrial anatomical variants. Multiplane reconstructions were used to measure PV diameters at 0, 5, 10, and 15 mm from the ostium in two phases (maximum and minimum size). The ejection fractions of three 5-mm segments were calculated for each PV. RESULTS: Right-sided and left-sided PV contraction and maximal atrial contraction occurred at a median of 85% and 95% of the cardiac cycle, respectively. The temporal concordance of minimal PV volume during peak atrial contraction indicated that the PV volume changes are secondary to active contraction rather than passive reflux and PV distension. The ejection fractions were highest in the superior veins: right superior PV (36.7%, 27.8%, and 16%, respectively, for the three segments from proximal to distal) and left superior PV (26.9%, 21.3%, and 12.1%), in comparison with the right inferior PV (21.1%, 6.6%, and -0.7%) and left inferior PV (15%, 9.3%, and 7.6%). CONCLUSION: Volume changes related to active PV contraction occur extending up to 15 mm into the veins, and this effect is most pronounced in the superior veins.

Abstract: Cosmetic intraocular iris implants for the purpose of changing iris color have recently been developed; however, little is known about their safety. We report a patient who had bilateral implantation of colored silicone iris implants solely for cosmetic reasons. The rapid development of uveitis, corneal decompensation, and ocular hypertension resulted in the need for explantation of the implants. Placement of these devices should require specific medical indications and meticulous surgery with early and long-term evaluation.

Abstract: OBJECTIVES: We assessed the efficacy of antitachycardia pacing (ATP) and low-energy (5J) shock for very fast ventricular tachycardia (VFVT), cycle length 200-250 ms, in patients with implantable cardioverter defibrillators (ICDs). METHODS AND RESULTS: One hundred and fifty-two consecutive patients with standard indications for ICD therapy were enrolled. Before discharge from the hospital each patient had an electrophysiological study (EPS) performed through the device, to assess the efficacy of ATP and low-joule shock at terminating VFVT. Initial therapy for VFVT consisted of three bursts of ATP followed by low-energy shock, and high-energy shocks as required. The mean age of enrolled patients was 63 +/- 13 years, and the mean left ventricular ejection fraction (LVEF) was 31 +/- 13%. During the predischarge EPS, a total of 125 VT episodes were induced in 64 patients. In patients with VFVT, the success rate of ATP was 30% (14/46), the acceleration rate was 26% (12/46), and the success rate of low-energy shock was 86% (25/29). In patients with fast ventricular tachycardia (FVT), cycle lengths 251-320 ms, the success rate of ATP was 62% (24/39), the acceleration rate was 18% (7/39), and the success rate of low-energy shock was 94% (17/18). CONCLUSIONS: This study has demonstrated for the first time that ATP and low-energy shock are effective, as an alternative to high-energy shock, to revert induced VFVT. Low-energy shock has a very high success rate for VT slower than VFVT. Clinical studies are required prior to consideration for empiric programming.

Abstract: INTRODUCTION: Transseptal puncture is required for many interventional procedures but has a serious complication rate of approximately 1%-primarily related to misidentification of the fossa ovalis resulting in inadvertent puncture of other cardiac structures. We investigated the utility of a full color visualization catheter to correctly position and guide transseptal puncture of the fossa ovalis. METHODS AND RESULTS: Transseptal puncture and left atrial cannulation were performed after visualization of the atrial septum and fossa ovalis with the visualization catheter (IRIS, Voyage Medical Inc.) on six swine. For each animal, the transseptal puncture was performed twice and the catheter was examined for clot after each puncture. The 12 transseptal punctures required 6.8 +/- 3.6 minutes procedural time and 300 +/- 94 mL of fluid administered per procedure (i.e., two punctures). IRIS visualization of the atrial septum correlated well with postmortem examination of the atrial septum. In the three animals in which a patent foramen ovale was present (as confirmed by pathological examination), it was also correctly identified by in vivo visualization using the IRIS catheter. CONCLUSION: The IRIS catheter allows direct in vivo visualization of the interatrial septum to guide transseptal puncture of previous punctures.

Abstract: INTRODUCTION: Ablation of the mitral isthmus to achieve bidirectional conduction block is technically challenging, and incomplete block slows isthmus conduction and is often proarrhythmic. The presence of the blood pool in the coronary venous system may act as a heat-sink, thereby attenuating transmural RF lesion formation. This porcine study tested the hypothesis that elimination of this heat-sink effect by complete air occlusion of the coronary sinus (CS) would facilitate transmural endocardial ablation at the mitral isthmus. METHODS: This study was performed in nine pigs using a 30 mm-long prototype linear CS balloon catheter able to occlude and displace the blood within the CS (the balloon was inflated with approximately 5 cc of air). Using a 3.5 mm irrigated catheter (35 W, 30 cc/min, 1 minute lesions), two sets of mitral isthmus ablation lines were placed per animal: one with the balloon deflated (CS open) and one inflated (CS Occluded). After ablation, gross pathological analysis of the linear lesions was performed. RESULTS: A total of 17 ablation lines were placed: 7 with CS Occlusion, and 10 without occlusion. Despite similar biophysical characteristics of the individual lesions, lesion transmurality was consistently noted only when using the air-filled CS balloon. CONCLUSIONS: Temporary displacement of the venous blood pool using an air-filled CS balloon permits transmurality of mitral isthmus ablation; this may obviate the need for ablation within the CS to achieve bidirectional mitral isthmus conduction.

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Abstract: INTRODUCTION: Irrigated-tip catheter ablation allows larger ablation lesions to be created, but also decreases catheter temperature monitoring accuracy. It is unclear which parameters should be monitored to optimize efficacy and safety during irrigated-tip ablation. METHODS AND RESULTS: Freshly excised hearts from eight male pigs were perfused and superfused using oxygenated swine blood in an ex vivo model. Ablations were performed for 1 minute using one of five different ablation protocols: (1) Temperature Control (42 degrees C 40 W), (2) Fixed Power 20 W, (3) Fixed Power 30 W, (4) Impedance Control (target 10 ohm impedance drop), and (5) Impedance Control (target 20 ohm drop). All ablations were performed with a perpendicular orientation of the catheter to the endocardial surface. Ablation lesions depth was significantly lower in the temperature control group (5.0 +/- 1.7 mm) compared with the fixed power ablation groups (6.5 +/- 1.0 mm for Power 20 W, 6.6 +/- 1.2 mm for Power 30 W). Impedance-controlled ablation created lesions intermediate in depth between fixed power and temperature controlled (6.0 +/- 1.6 for Impedance 10 ohms and 6.2 +/- 1.4 mm for Impedance 20 ohms groups). There was a significantly greater incidence of pops and thrombus formation in the Power 20 W (9/14), Power 30 W (10/14), and Impedance 20 ohms (10/16) groups than the Temperature Control (1/16) and Impedance control 10 ohms (2/16) groups. CONCLUSION: Temperature control improved the safety profile during irrigated-tip ablation in comparison with fixed-power ablations, but resulted in significantly smaller lesions. Impedance-controlled ablation lesions (target 10 ohm drop) created lesions of comparable size to fixed-power ablations with a significantly better safety profile.

Abstract: BACKGROUND AND PURPOSE: There is emerging evidence that coronary catheterization can cause cerebrovascular embolization. We aimed to assess the proportion of cardiac patients with retinal emboli before coronary catheterization and the proportion with newly developed retinal embolism shortly after coronary catheterization. METHODS: Ninety-seven patients attending Westmead Hospital for coronary catheterization between December 2005 and February 2006 were recruited. Medical history, physical examination, and pre- and postcatheterization photography of 5 retinal fields was performed. The proportion of patients with new retinal emboli was assessed by comparing post- and precatheterization retinal photographs. RESULTS: Before catheterization, retinal emboli were observed in 5 patients (5.2%) and were significantly associated with higher body mass index (P=0.007). The presence of angiographic coronary artery disease was not significantly associated with preexisting retinal emboli. In 97 patients, we found no new emboli within the 16-hour (median: range 4 to 45 hours) postcoronary catheterization period. CONCLUSIONS: Asymptomatic retinal emboli are relatively common in patients being assessed for coronary artery disease. We found no evidence suggesting coronary catheterization contributes to retinal embolism shortly after the procedure.

Abstract: INTRODUCTION: Pericarditis is a potential complication of catheter-based percutaneous epicardial mapping and ablation. This study evaluates the efficacy and safety of intrapericardial instillation of anti-inflammatory agents after pericardial mapping and ablation in a porcine model of postprocedural pericarditis. METHODS AND RESULTS: Twenty-five healthy swine underwent epicardial mapping and ablation after transthoracic subxyphoid puncture. After 60 minutes of continuous catheter manipulation in the pericardial space, radiofrequency energy was delivered in a linear fashion to the epicardial surfaces of both atria. The animals were randomly divided to receive the anti-inflammatory agents, Hyaluronic Acid and Triamcinolone, or control. Fourteen days after ablation, the hearts were excised and the degree of pericardial reaction/adhesions scored. The severity was uniformly graded 4 (intense) in all control animals and was characterized by intense adhesion between the parietal and the visceral pericardium obscuring tissue planes and epicardial anatomy. Hyaluronic Acid provided a mild benefit (score 3.0 +/- 0.9), but 2 mg/kg of Triamcinolone significantly attenuated the inflammatory effect (all animals uniformly scored 1.0). CONCLUSION: In a porcine model of ablation-related pericarditis, intrapericardial instillation of 2 mg/kg of intermediate-acting corticosteroids effectively prevents post-procedure inflammatory adhesion formation.

Abstract: BACKGROUND: Substrate mapping using a magnetic electroanatomical mapping system (MEAM) has been shown to accurately delineate the location/extent of scarred myocardium. This study examined the ability of a sonomicrometry-based electroanatomic mapping system (SEAM) to render endocardial and epicardial substrate maps of infarcted ventricular myocardium. METHODS AND RESULTS: In 7 swine with healed myocardial infarctions, combined epicardial and endocardial left ventricular (LV) substrate maps were created with both SEAM and MEAM mapping systems using 246+/-68 and 244+/-44 points respectively. Scarred myocardium was identified based upon bipolar electrogram amplitude < 1.5 mV, and radiofrequency ablation lesions were delivered to the scar border as defined by the sonomicrometry mapping system. The LV endocardial chamber volume as defined by SEAM (125+/-46 ml) correlated well with that defined by the MEAM (137+/-45 ml, r=0.77, p < 0.05). The area of infarcted tissue as determined by SEAM was highly correlated with that determined by gross pathology (r=0.96 for endocardial scar and r=0.92 for epicardial scar p < 0.05). The scar area calculated by the SEAM system also correlated well with the scar area determined by the MEAM system (0.91 for endocardial scar and 0.90 for epicardial scar p < 0.05). Finally, the sonomicrometry-based system was able to guide the placement of radiofrequency ablation lesions to the borders of the scar. CONCLUSIONS: This study demonstrates that the sonomicrometry-based mapping can accurately reconstruct three-dimensional voltage maps of the endocardial and epicardial ventricular surfaces and guide the placement of ablation lesions along the scar border zone.

Abstract: BACKGROUND: Certain tachycardias can be eliminated by catheter ablation from within the base of the aortic valve (AV) cusps but the high blood flow and proximity to the coronary arteries create unique challenges. Standard radiofrequency (RF) energy, cooled-tip RF energy or cryothermal energy were compared to determine the optimal ablation modality. MATERIALS AND METHODS: Experiments were conducted using adult swine or goats (15 animals). Ablation lesions were placed using either: temperature-controlled RF (4 mm-tip catheter; 60 degrees C/60 s), cooled-tip RF (4 mm-tip catheter with internal saline circulation at 0.6 ml/s; 40 degrees C/60 s), or cryoablation (6 mm-tip spot cryocatheter; <-75 degrees C/4 min). Animals were sacrificed 1 h after the last application and lesions were subject to pathological analysis. RESULTS: Standard RF and cryoablation created similar depth lesions in the right coronary cusp (4.2+/-1.3 and 3.4+/-0.5 mm, respectively) but cryoablation was unable to create any visible lesions in the non-coronary cusp. Cooled tip ablation created larger ablation lesions in the right coronary cusp (5.25+/-0.5) and fully transmural left atrial ablation lesions after ablation in the noncoronary cusp. Acute damage to the cusps was not noted with any ablation modality. Disruption of elastic fibers in the aortic media was seen after standard and cooled tip radiofrequency ablation but not cryoablation. CONCLUSION: Cryoablation within the AV cusps created similar sized lesions to standard RF ablation without evidence of elastic fibre disruption and may therefore be an appropriate first line ablation modality. Cooled-tip ablation created larger ablation lesions and therefore may be required if cryoablation is ineffective.

Abstract: Coronary Irrigation Near Epicardial Ablation. Introduction: The coronary arteries can be damaged during epicardial radiofrequency ablation (RFA) procedures. We hypothesized that intracoronary irrigation with chilled saline may be a useful technique for minimizing heat-induced damage to the coronary artery endothelium during this procedure. Methods and Results: Twenty-nine ablation procedures were performed on 17 freshly excised ovine hearts. Radiofrequency current was delivered through an internally cooled, 4-mm-tip ablation catheter placed directly over the coronary artery (24 applications) and over noncoronary epicardium (5 applications). An Amplatz coronary catheter was used to internally irrigate the coronary artery with either 37 degrees C or 5 degrees C 0.9% saline (12 ablations each group). Fluroptic temperature probes were placed within the artery lumen under the ablation site and 15 mm distal from the ablation site. The peak intracoronary temperature directly under the ablation catheter was significantly lower (P = 0.001) in the chilled than in the nonchilled saline irrigation group (23.6 degrees C, interquartile range [IQR] 15.7-39.8 vs 54.6 degrees C, IQR 48.9-58.6). Blue tetrazolium stained lesion sections showed that the median distance between the ablation lesion and the artery wall was significantly higher (P = 0.004) for the chilled versus the nonchilled saline irrigation group (0.42 mm, IQR 0.25-0.70 vs 0.00 mm, IQR 0.00-0.28). Conclusions: Intracoronary irrigation with chilled saline may protect the coronary artery endothelium from heat-induced damage during epicardial RFA.

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Abstract: OBJECTIVES: To design and test a catheter that could create deeper ablation lesions. BACKGROUND: Endocardial radiofrequency (RF) ablation is unable to reliably create transmural ventricular lesions. We designed an intramural needle ablation catheter with an internally cooled 1.1-mm diameter straight needle that could be advanced up to 14 mm into the myocardium. The prototype catheter was compared with an irrigated tip ablation catheter. METHODS: Ablation lesions were created under general anesthesia in 14 male sheep (weight 44 +/- 7.3 kg) with fluoroscopic guidance. Each of the catheters was used to create two ablation lesions at randomly allocated positions within the left ventricle. The irrigation rate, target temperature, and maximum power were: 20 mL/min, 85 degrees C, 50 W for the intramural needle catheter and 20 mL/min, 50 degrees C, 50 W for the irrigated tip catheter, respectively. All ablations were performed for 2 minutes. After the last ablation, blue tetrazolium (12.5 mg/kg) was infused intravenously. The heart was removed via a left thoracotomy after monitoring the sheep for one hour. RESULTS: There was no evidence of cardiac tamponade in any sheep. The intramural needle catheter lesions were significantly wider (10.9 +/- 2.8 mm vs 10.1 +/- 2.4 mm, P = 0.01), deeper (9.6 +/- 2.0 mm vs 7.0 +/- 1.3 mm, P = 0.01), and more likely to be transmural (38% vs 0%, P = 0.03). CONCLUSIONS: Cooled intramural needle ablation creates lesions that are significantly deeper and wider than endocardial RF ablation using an irrigated tip catheter in sheep hearts. This technology may be useful in treating ventricular tachycardia resistant to conventional ablation techniques.

Abstract: BACKGROUND: Studies of ventricular fibrillation (VF) in small mammals have revealed localized sustained stationary reentry. However, studies in large mammals with surface mapping techniques have demonstrated only relatively short-lived rotors. The purpose of this study was to identify whether sustained high-frequency activation with low beat-to-beat variability was present at intramural sites in a postinfarct ovine model of VF. METHODS AND RESULTS: VF was induced in 12 sheep 77+/-40 days after anterior myocardial infarction. Electrical activation was recorded with 20 multielectrode transmural plunge needles. Unipolar electrogram frequency content and local cycle duration variability were studied in 30-second recordings beginning 5 seconds after the onset of VF. Higher mean beat frequency was associated with lower SD of the cycle duration intervals (r=-0.91, P<0.001). The mean beat frequency and the SD of cycle duration intervals of the highest-frequency electrode were 8.8+/-2.0 Hz and 17+/-11 ms. In 3 cases, a region with regular activation throughout the recording was identified (SD of the cycle duration interval, 6.0+/-0.7 ms). Two of these sites and 67% of all sites with low local cycle duration variability were intramural. They occurred within regions with a high dominant frequency as determined by fast Fourier transform of the unipolar electrogram. CONCLUSIONS: Regions with the highest frequency of activation during VF were always associated with a low local cycle duration variability and usually intramural in this chronic infarct model. In a minority of cases, a region of stable, rapid, and very regular activation could be identified. These findings support the hypothesis that relatively stable periodic sources form a component of the mechanism of VF in this model.

Abstract: BACKGROUND: We assessed the hypothesis that "virtual electrograms" from a noncontact mapping system (EnSite 3000) could be used to localize myocardial scar. METHODS AND RESULTS: Myocardial infarctions were induced in sheep by inflating an angioplasty balloon in the left anterior descending coronary artery for 3 hours. Scar mapping was performed on 8 sheep without inducible ventricular tachycardia by use of the noncontact mapping system and a 256-channel contact mapping system. Transmural mapping needles were inserted into myocardial regions that were (1) scarred, (2) peripheral to the scar, and (3) distant from the scar. Unipolar electrograms were exported from both systems and analyzed on a personal computer workstation. The percentage of myocardial scarring at each needle site was assessed histologically. Pearson's correlation was used to assess the degree of association between various electrogram characteristics and the presence of myocardial scarring. The only noncontact electrogram characteristic that showed any association with the presence of myocardial scarring was the negative slope duration (contact, r=0.62, P<0.001; noncontact, r=0.23, P=0.004). The other electrogram characteristics studied were electrogram maximal deflection (contact, r=0.38, P<0.001; noncontact, r=0.03, P=0.75) and minimal slope (contact, r=0.42, P<0.001; noncontact, r=0.05, P=0.54). CONCLUSIONS: Noncontact electrograms do not reliably identify ventricular scar. Alternative strategies such as importing computed tomography images into the geometry should be used when scar localization is important.

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Abstract: THIAGALINGAM, A., et al.: Cooled Intramural Needle Catheter Ablation Creates Deeper Lesions than Irrigated Tip Catheter Ablation.Endocardial radiofrequency ablation of the left ventricle does not create transmural lesions reliably even with active electrode cooling. The authors developed a prototype catheter with an internally cooled needle electrode that could be advanced an adjustable distance into the myocardium. Freshly excised hearts from eight male sheep were perfused and superfused using oxygenated ovine blood. Ablations were performed for 2 minutes using the prototype catheter and a conventional endocardial 5-mm irrigated tip ablation catheter at target temperatures of 80 degrees C and 50 degrees C, respectively. The prototype catheter needle was inserted 12 mm deep for all ablations. The maximal power and irrigation rate was 50 W, 20 mL/min for the irrigated tip catheter and 20 W, 10 mL/min for the intramural needle catheter. Intramural needle lesions were significantly deeper (13.5 +/- 2.3 vs 9.1 +/- 1.3 mm, P < 0.01) but less wide (8.7 +/- 1.5 vs 12.7 +/- 1.9 mm, P < 0.01) than irrigated tip lesions. Popping occurred during 12 (37%) of the 32 irrigated tip ablations. Popping did not occur during intramural needle ablation. The cooled intramural needle ablation catheter creates lesions that are significantly deeper than irrigated tip catheters with less tissue boiling. In contrast to irrigated tip ablation, electrode temperature monitoring can be used to determine if a lesion has been created during intramural needle ablation. The cooled intramural needle ablation lesions were of a clinically useful width, addressing one of the main recognized deficiencies of intramural needle ablation. (PACE 2004; 27:965-970)

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Abstract: Radiofrequency ablation of the left ventricle using an endocardially placed electrode is unable to reliably create transmural lesions even with active electrode cooling. To produce deeper radiofrequency lesions, the authors developed and tested a prototype intramural needle ablation catheter that had a distal 1.1-mm diameter straight needle that could be advanced 12 mm into the myocardium. Freshly excised hearts from eight male sheep were perfused and superfused with oxygenated ovine blood. Ablations were performed for 60 seconds with the prototype catheter and a conventional 5-mm irrigated tip ablation catheter at target temperatures of 90 degrees C and 50 degrees C, respectively. The ablation lesions were bisected and stained with blue tetrazolium to assess lesion geometry. The irrigated tip ablation catheter required significantly more power than the intramural needle ablation catheter (37.7 +/- 7.3 vs 6.4 +/- 2.1 W, P < 0.01). Intramural needle lesions were significantly deeper (12.5 +/- 3.0 mm vs 8.3 +/- 2.1 mm, P < 0.01) but less wide (3.9 +/- 1.1 mm vs 11.5 +/- 2.0 mm, P < 0.01) than irrigated tip lesions. There was a high incidence of crater formation (74%), popping (45%), and myocardial charring (29%) during irrigated tip ablation; these phenomena were not observed during intramural needle ablation. The intramural needle ablation catheter creates significantly deeper but narrower lesions without evidence of tissue boiling. This technology may be particularly useful for ablation of ventricular tachycardia originating from regions where tissue depth is increased, like the ventricular septum.

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Abstract: Male to female transsexual clients are a group of clients for whom there are few dedicated services in New Zealand. To examine service utilization in Wellington, New Zealand, 70 male to female transsexual clients were identified and their medical records audited for selected aspects of sexual health service delivery. Audit revealed that sexual health history is recorded incompletely and behavioural risk factors are not fully explored, sexual health examination and testing is incomplete. We conclude opportunities to expose relevant behavioural factors and to educate for sexual safety and health promotion are lost with this infrequently attending minority client group.