Benhur Henz

Three-dimensional ultrasound for image-guided mapping and intervention: methods, quantitative validation, and clinical feasibility of a novel multimodality image mapping system.

Background— Multiple factors create discrepancies between electroanatomic maps and merged, preacquired computed tomographic images used in guiding atrial fibrillation ablation. Therefore, a Carto-based 3D ultrasound image system (Biosense Webster Inc) was validated in an animal model and tested in 15 atrial fibrillation patients. Methods and Results— Twelve dogs underwent evaluation using a newly developed Carto-based 3D ultrasound system. After fiducial clip markers were percutaneously implanted at critical locations in each cardiac chamber, 3D ultrasound geometries, derived from a family of 2D intracardiac echocardiographic images, were constructed. Point-source error of 3D ultrasound-derived geometries, assessed by actual real-time 2D intracardiac echocardiographic clip sites, was 2.1±1.1 mm for atrial and 2.4±1.2 mm for ventricular sites. These errors were significantly less than the variance on CartoMerge computed tomographic images (atria: 3.3±1.6 mm; ventricles: 4.8±2.0 mm; P< 0.001 for both). Target ablation at each clip, guided only by 3D ultrasound-derived geometry, resulted in lesions within 1.1±1.1 mm of the actual clips. Pulmonary vein ablation guided by 3D ultrasound-derived geometry resulted in circumferential ablative lesions. Mapping in 15 patients produced modestly smaller 3D ultrasound versus electroanatomic map left atrial volumes (98±24 cm3 versus 109±25 cm3, P< 0.05). Three-dimensional ultrasound-guided pulmonary vein isolation and linear ablation in these patients were successfully performed with confirmation of pulmonary vein entrance/exit block. Conclusions— These data demonstrate that 3D ultrasound images seamlessly yield anatomically accurate chamber geometries. Image volumes from the ultrasound system are more accurate than possible with CartoMerge computed tomographic imaging. This clinical study also demonstrates the initial feasibility of this guidance system for ablation in patients with atrial fibrillation. Received September 18, 2007; accepted April 7, 2008. # CLINICAL PERSPECTIVE {#article-title-2}Background—Multiple factors create discrepancies between electroanatomic maps and merged, preacquired computed tomographic images used in guiding atrial fibrillation ablation. Therefore, a Carto-based 3D ultrasound image system (Biosense Webster Inc) was validated in an animal model and tested in 15 atrial fibrillation patients. Methods and Results—Twelve dogs underwent evaluation using a newly developed Carto-based 3D ultrasound system. After fiducial clip markers were percutaneously implanted at critical locations in each cardiac chamber, 3D ultrasound geometries, derived from a family of 2D intracardiac echocardiographic images, were constructed. Point-source error of 3D ultrasound-derived geometries, assessed by actual real-time 2D intracardiac echocardiographic clip sites, was 2.1±1.1 mm for atrial and 2.4±1.2 mm for ventricular sites. These errors were significantly less than the variance on CartoMerge computed tomographic images (atria: 3.3±1.6 mm; ventricles: 4.8±2.0 mm; P<0.001 for both). Target ablation at each clip, guided only by 3D ultrasound-derived geometry, resulted in lesions within 1.1±1.1 mm of the actual clips. Pulmonary vein ablation guided by 3D ultrasound-derived geometry resulted in circumferential ablative lesions. Mapping in 15 patients produced modestly smaller 3D ultrasound versus electroanatomic map left atrial volumes (98±24 cm3 versus 109±25 cm3, P<0.05). Three-dimensional ultrasound-guided pulmonary vein isolation and linear ablation in these patients were successfully performed with confirmation of pulmonary vein entrance/exit block. Conclusions—These data demonstrate that 3D ultrasound images seamlessly yield anatomically accurate chamber geometries. Image volumes from the ultrasound system are more accurate than possible with CartoMerge computed tomographic imaging. This clinical study also demonstrates the initial feasibility of this guidance system for ablation in patients with atrial fibrillation.

Luminal Esophageal Temperature Monitoring With a Deflectable Esophageal Temperature Probe and Intracardiac Echocardiography May Reduce Esophageal Injury During Atrial Fibrillation Ablation Procedures Results of a Pilot Study

Background— Luminal esophageal temperature (LET) monitoring is one strategy to minimize esophageal injury during atrial fibrillation ablation procedures. However, esophageal ulceration and fistulas have been reported despite adequate LET monitoring. The objective of this study was to assess a novel approach to LET monitoring with a deflectable LET probe on the rate of esophageal injury in patients undergoing atrial fibrillation ablation. Methods and Results— Forty-five consecutive patients undergoing an atrial fibrillation ablation procedure followed by esophageal endoscopy were included in this prospective observational pilot study. LET monitoring was performed with a 7F deflectable ablation catheter that was positioned as close as possible to the site of left atrial ablation using the deflectable component of the catheter guided by visualization of its position on intracardiac echocardiography. Ablation in the posterior left atrial was limited to 25 W and terminated when the LET increased 2°C from baseline. Endoscopy was performed 1 to 2 days after the procedure. All patients had at least 1 LET elevation >2°C necessitating cessation of ablation. Deflection of the LET probe was needed to accurately measure LET in 5% of patients when ablating near the left pulmonary veins, whereas deflection of the LET probe was necessary in 88% of patients when ablating near the right pulmonary veins. The average maximum increase in LET was 2.5±1.5°C. No patients had esophageal thermal injury on follow-up endoscopy. Conclusions— A strategy of optimal LET probe placement using a deflectable LET probe and intracardiac echocardiography guidance, combined with cessation of radiofrequency ablation with a 2°C rise in LET, may reduce esophageal thermal injury during left atrial ablation procedures.

Successful radiofrequency ablation of the cerebral cortex in pigs using the venous system: possible implications for treating CNS disorders.

BACKGROUND When pharmacotherapy for epilepsy fails, surgical options, although efficacious, are highly invasive. We explored whether ablation of the cerebral cortex can be performed utilizing the cerebral venous system. METHODS Mapping and radiofrequency ablation was performed via the venous system in two pigs. RESULTS Eight targeted sites were successfully accessed and four targeted sites successfully ablated via the central cerebral venous network. CONCLUSION Electrophysiological mapping and radiofrequency ablation of the cerebral cortex can be performed via the cerebral veins.

Advances in radiofrequency ablation of the cerebral cortex in primates using the venous system: Improvements for treating epilepsy with catheter ablation technology

BACKGROUND Pharmacology frequently fails for the treatment of epilepsy. Although surgical techniques are effective, these procedures are highly invasive. We describe feasibility and efficacy of minimally invasive mapping and ablation for the treatment of epilepsy. METHODS Mapping and radiofrequency ablations were performed via the venous system in eleven baboons and three dogs. RESULTS Mapping in deep cerebral areas was obtained in all animals. High-frequency pacing was able to induce seizure activity of local cerebral tissue in 72% of our attempts. Cerebral activity could be seen during mapping. Ablative lesions were deployed at deep brain sites without steam pops or sudden impedance rise. Histologic analysis showed necrosis at the sites of ablation in all primates. CONCLUSION Navigation through the cerebral venous system to map seizure activity is feasible. Radiofrequency energy can be delivered transvenously or transcortically to successfully ablate cortical tissue in this animal model using this innovative approach.

Catecholaminergic polymorphic ventricular tachycardia: a current overview.

Catecholaminergic polymorphic ventricular tachycardia occurs in healthy children and young adults causing syncope and sudden cardiac death. This is a familial disease, which affect de novo mutation in 50% of the cases. At least two causative genes have been described to be localized in the chromosome 1; mutation of the ryanodine receptor gene and calsequestrin gene. The classical clinical presentation is syncope triggered by exercise and emotion in children and adolescents with no structural heart disease. Polymorphic ventricular tachycardia during treadmill testing, or after isoproterenol infusion, is the most common feature. Therapeutic options include, beta-blockers, calcium-channel blockers and, an implantable cardioverter defibrillator is indicated in high-risk patients. Risk stratification of this disease is very challenging, since some risk factors proved to be useful in some series but not in others. However, family history of sudden cardiac death and symptoms initiated in very young children are important predictors.

Utility of intracardiac ultrasound imaging to guide pulmonary vein ablation using laser balloon catheter

FUNDAMENTO: O isolamento das veias pulmonares (IVP) tem sido usado como endpoint para a ablacao da fibrilacao atrial (FA) com cateter balao. OBJETIVO: Determinar a utilidade do ultrassom intracardiaco (USIC) para guiar o IVP, usando cateter balao a laser. METODOS: 59 VP foram ablacionadas em 27 caes. Imagens de Doppler foram usadas para identificar os vazamentos do fluxo sanguineo entre a VP e o balao. Apos cada liberacao de energia, o cateter de mapeamento circular foi reposicionado para verificar se o isolamento tinha sido obtido. A posicao de vazamento foi entao correlacionada com a posicao do gap no estudo patologico. A analise de regressao logistica multivariada foi realizada. RESULTADOS: Cinquenta e nove VP foram submetidas a ablacao. O tempo medio de energia liberada foi de 279±177 seg., o diâmetro medio do balao era de 23±3 mm, e o comprimento medio do balao era 25±4 mm. O isolamento completo foi obtido em 38/59 (64%), e foi significantemente mais comum sem vazamento: [30/38 (79%) versus 8/23 (35%), p<0,001]. Isso foi independente do tempo de aplicacao (302±223 seg. vs. 266±148 sec., p=ns), potencia (3,5 W/cm, 4,5 W/cm, e 5,5 W/cm), diâmetro do balao (24± 3 mm vs. 22± 3 mm, p= ns) e comprimento (27±4 mm vs. 24±4 mm, p=ns). O valor preditivo positivo para previsao de isolamento completo foi de 65% e o valor preditivo negativo foi 83%. CONCLUSAO: Um vazamento identificavel entre a VP e o dispositivo de ablacao por cateter-balao observado no USIC e preditor de menor taxa de isolamento de VP mais baixas. O USIC pode ser util para detectar vazamentos a fim de evitar o uso ineficaz de aplicacao energia durante a ablacao circunferencial da VP. Isto tambem pode ser util quando outras energias sao utilizadas.BACKGROUND Pulmonary vein isolation (PVI) with balloon catheter has been used as the endpoint for AF ablation. OBJECTIVE To determine the usefulness of intracardiac ultrasound (ICUS) to guide PVI using laser balloon catheter. METHODS 59 PVs were ablated in 27 dogs. Doppler imaging was used to identify blood flow leaks between PV and balloon. After each energy delivery, the circular mapping catheter was repositioned to check if isolation had been achieved. The leak position was then correlated with the gap position at the pathological study. Multivariate logistic regression analysis was undertaken. RESULTS 59 PV were ablated. Mean burn time was 279+/-177 sec, mean balloon diameter was 23+/-3 mm, and mean balloon length was 25+/-4 mm. Complete isolation was achieved in 38/59 (64%) cases, and it was significantly more common when there was no leak: [30/38 (79%) versus 8/23 (35%), p<0.001]. This occurred regardless of time of laser application (302+/-223 sec. vs. 266+/-148 sec., p=ns), laser power (3.5 W/cm, 4.5 W/cm, and 5.5 W/cm), balloon diameter (24+/- 3 mm vs. 22+/- 3 mm, p=ns) and length (27+/-4 mm vs. 24+/-4mm, p=ns). The positive predictive value for predicting incomplete isolation was 65% and the negative predictive value was 83%. CONCLUSION An identifiable leak between PV and the LBA device seen at the ICUS is predictive of lower PV isolation rates. ICUS may be useful for leak detection to avoid ineffective energy application during circumferential PV ablation. This could also be helpful when other types of energy are used.

Atrial Fibrillation and Cryptogenic Thromboembolic Events

DOI: 10.5935/abc.20180141 Annual stroke rates are extremely high, affecting around 15 million individuals worldwide, generating major public health and economic impact. Approximately 25% of stroke cases do not have a determined etiology, thus being denominated cryptogenic stroke (CS).1 Cryptogenic strokes do not have a definite cause; their identification occurs by exclusion, when they are not attributable to definite cardioembolism, large-vessel atherosclerosis of and small-vessel disease, despite extensive vascular, cardiac or serological investigation.2

Novel Techniques in Epilepsy Management: Venous Pacing and Capture of Electrical Activity in the Primate Cortex.

OBJECTIVE Pharmacotherapy for epilepsy is limited with 30% of patients refractory to this approach of suppressing seizures. Current surgical options are invasive and carry significant morbidities including infection, bleeding, and the potential for deleterious neurocognitive effects. As a result, there is a burgeoning need for innovation to develop safer and efficacious interventions. METHODS Four distinct catheters (2 existing: Cardima catheter, Standard EPT Blazer catheter; 2 new prototypes: balloon catheter, basket catheters) were tested in 12 baboons (21-30 kg, 100% male). For each, we assessed whether or not the catheter was able to be maneuvered safely in various locations of the cerebral venous system, provide adequate cortical tissue contact to record signals, detect these signals as normal or abnormal, successfully stimulate the cortex, and capture the cortical tissue. Locations trialed included the petrosal sinus, straight sinus, vein of Galen, and occipital vein. Pacing cycle length and pacing thresholds varied among experiments. RESULTS Successful mapping was conducted in all 12 baboons. The pacing cycle length varied from 75 ms to 650 ms depending on location of the cortex. Pacing threshold was recorded in 4/12 (33%) of the experiments; data is not available for the remaining 8/12 experiments. The threshold values ranged from 0.3 - 20 mAmps. Capture of cortical electrical activity was observed in 11/12 (91.7 %) experiments though the number of successful capture and stimulation attempts varied among experiments. The most reliable and consistent capture occurred with the use of our novel prototyped over-the-wire balloon catheter (9/12; 75%) and basket catheter (3/3; 100%). Necropsy and histology were performed post-experimentation, and only minimal complications were noted (Table 1). CONCLUSION New electrode design can be maneuvered safely in the venous system, provide adequate cortical tissue contact to record signals, detect these signals as normal or abnormal, successfully stimulate the cortex, and capture cortical tissue. These novel devices merit further study in chronic baboons to establish long-term efficacy of continuous seizure recording.

Utilidade do Ultrassom intracardíaco no isolamento de veias pulmonares usando cateter-balão a laser

FUNDAMENTO: O isolamento das veias pulmonares (IVP) tem sido usado como endpoint para a ablacao da fibrilacao atrial (FA) com cateter balao. OBJETIVO: Determinar a utilidade do ultrassom intracardiaco (USIC) para guiar o IVP, usando cateter balao a laser. METODOS: 59 VP foram ablacionadas em 27 caes. Imagens de Doppler foram usadas para identificar os vazamentos do fluxo sanguineo entre a VP e o balao. Apos cada liberacao de energia, o cateter de mapeamento circular foi reposicionado para verificar se o isolamento tinha sido obtido. A posicao de vazamento foi entao correlacionada com a posicao do gap no estudo patologico. A analise de regressao logistica multivariada foi realizada. RESULTADOS: Cinquenta e nove VP foram submetidas a ablacao. O tempo medio de energia liberada foi de 279±177 seg., o diâmetro medio do balao era de 23±3 mm, e o comprimento medio do balao era 25±4 mm. O isolamento completo foi obtido em 38/59 (64%), e foi significantemente mais comum sem vazamento: [30/38 (79%) versus 8/23 (35%), p<0,001]. Isso foi independente do tempo de aplicacao (302±223 seg. vs. 266±148 sec., p=ns), potencia (3,5 W/cm, 4,5 W/cm, e 5,5 W/cm), diâmetro do balao (24± 3 mm vs. 22± 3 mm, p= ns) e comprimento (27±4 mm vs. 24±4 mm, p=ns). O valor preditivo positivo para previsao de isolamento completo foi de 65% e o valor preditivo negativo foi 83%. CONCLUSAO: Um vazamento identificavel entre a VP e o dispositivo de ablacao por cateter-balao observado no USIC e preditor de menor taxa de isolamento de VP mais baixas. O USIC pode ser util para detectar vazamentos a fim de evitar o uso ineficaz de aplicacao energia durante a ablacao circunferencial da VP. Isto tambem pode ser util quando outras energias sao utilizadas.BACKGROUND Pulmonary vein isolation (PVI) with balloon catheter has been used as the endpoint for AF ablation. OBJECTIVE To determine the usefulness of intracardiac ultrasound (ICUS) to guide PVI using laser balloon catheter. METHODS 59 PVs were ablated in 27 dogs. Doppler imaging was used to identify blood flow leaks between PV and balloon. After each energy delivery, the circular mapping catheter was repositioned to check if isolation had been achieved. The leak position was then correlated with the gap position at the pathological study. Multivariate logistic regression analysis was undertaken. RESULTS 59 PV were ablated. Mean burn time was 279+/-177 sec, mean balloon diameter was 23+/-3 mm, and mean balloon length was 25+/-4 mm. Complete isolation was achieved in 38/59 (64%) cases, and it was significantly more common when there was no leak: [30/38 (79%) versus 8/23 (35%), p<0.001]. This occurred regardless of time of laser application (302+/-223 sec. vs. 266+/-148 sec., p=ns), laser power (3.5 W/cm, 4.5 W/cm, and 5.5 W/cm), balloon diameter (24+/- 3 mm vs. 22+/- 3 mm, p=ns) and length (27+/-4 mm vs. 24+/-4mm, p=ns). The positive predictive value for predicting incomplete isolation was 65% and the negative predictive value was 83%. CONCLUSION An identifiable leak between PV and the LBA device seen at the ICUS is predictive of lower PV isolation rates. ICUS may be useful for leak detection to avoid ineffective energy application during circumferential PV ablation. This could also be helpful when other types of energy are used.

Utilidad del ultrasonido intracardíaco en el aislamiento de venas pulmonares usando catéter-balón láser

FUNDAMENTO: O isolamento das veias pulmonares (IVP) tem sido usado como endpoint para a ablacao da fibrilacao atrial (FA) com cateter balao. OBJETIVO: Determinar a utilidade do ultrassom intracardiaco (USIC) para guiar o IVP, usando cateter balao a laser. METODOS: 59 VP foram ablacionadas em 27 caes. Imagens de Doppler foram usadas para identificar os vazamentos do fluxo sanguineo entre a VP e o balao. Apos cada liberacao de energia, o cateter de mapeamento circular foi reposicionado para verificar se o isolamento tinha sido obtido. A posicao de vazamento foi entao correlacionada com a posicao do gap no estudo patologico. A analise de regressao logistica multivariada foi realizada. RESULTADOS: Cinquenta e nove VP foram submetidas a ablacao. O tempo medio de energia liberada foi de 279±177 seg., o diâmetro medio do balao era de 23±3 mm, e o comprimento medio do balao era 25±4 mm. O isolamento completo foi obtido em 38/59 (64%), e foi significantemente mais comum sem vazamento: [30/38 (79%) versus 8/23 (35%), p<0,001]. Isso foi independente do tempo de aplicacao (302±223 seg. vs. 266±148 sec., p=ns), potencia (3,5 W/cm, 4,5 W/cm, e 5,5 W/cm), diâmetro do balao (24± 3 mm vs. 22± 3 mm, p= ns) e comprimento (27±4 mm vs. 24±4 mm, p=ns). O valor preditivo positivo para previsao de isolamento completo foi de 65% e o valor preditivo negativo foi 83%. CONCLUSAO: Um vazamento identificavel entre a VP e o dispositivo de ablacao por cateter-balao observado no USIC e preditor de menor taxa de isolamento de VP mais baixas. O USIC pode ser util para detectar vazamentos a fim de evitar o uso ineficaz de aplicacao energia durante a ablacao circunferencial da VP. Isto tambem pode ser util quando outras energias sao utilizadas.BACKGROUND Pulmonary vein isolation (PVI) with balloon catheter has been used as the endpoint for AF ablation. OBJECTIVE To determine the usefulness of intracardiac ultrasound (ICUS) to guide PVI using laser balloon catheter. METHODS 59 PVs were ablated in 27 dogs. Doppler imaging was used to identify blood flow leaks between PV and balloon. After each energy delivery, the circular mapping catheter was repositioned to check if isolation had been achieved. The leak position was then correlated with the gap position at the pathological study. Multivariate logistic regression analysis was undertaken. RESULTS 59 PV were ablated. Mean burn time was 279+/-177 sec, mean balloon diameter was 23+/-3 mm, and mean balloon length was 25+/-4 mm. Complete isolation was achieved in 38/59 (64%) cases, and it was significantly more common when there was no leak: [30/38 (79%) versus 8/23 (35%), p<0.001]. This occurred regardless of time of laser application (302+/-223 sec. vs. 266+/-148 sec., p=ns), laser power (3.5 W/cm, 4.5 W/cm, and 5.5 W/cm), balloon diameter (24+/- 3 mm vs. 22+/- 3 mm, p=ns) and length (27+/-4 mm vs. 24+/-4mm, p=ns). The positive predictive value for predicting incomplete isolation was 65% and the negative predictive value was 83%. CONCLUSION An identifiable leak between PV and the LBA device seen at the ICUS is predictive of lower PV isolation rates. ICUS may be useful for leak detection to avoid ineffective energy application during circumferential PV ablation. This could also be helpful when other types of energy are used.