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1.
Artigo em Inglês | MEDLINE | ID: mdl-38752962

RESUMO

BACKGROUND: Accurate measurements of intracardiac electrograms (EGMs) remain a clinical challenge because of the suboptimal attenuation of far-field potentials. Multielectrode mapping catheters provide an opportunity to construct multipolar instead of bipolar EGMs for rejecting common far-field potentials recorded from a multivectorial space. OBJECTIVES: The purpose of this study was to develop a multipolar EGM and compare its characteristics to those of bipolar EGMs METHODS: Using a 36-electrode array catheter (Optrell-36; Biosense Webster), a far-field component was mathematically constructed from clusters of electrodes surrounding each inspected electrode. This component was subtracted from the unipolar waveform to produce a local unipolar, referred to as a "multipolar EGM." The performance of multipolar EGMs was evaluated in 7 swine with healed anteroseptal infarction. RESULTS: Multipolar EGMs proved superior in attenuating far-field potentials in infarct border zones, increasing the near-field to far-field ratio from 0.92 ± 0.2 to 2.25 ± 0.3 (P < 0.001). Removal of far-field components reduced the voltage amplitude (P < 0.001) and enlarged the infarct surface area (P = 0.02), aligning more closely with histological findings. Of 379 EGMs with ≥20 ms activation time difference between bipolar and multipolar EGMs, 95.3% (361 of 379) were accurately annotated using multipolar EGMs, while annotation based on bipolar EGM was predominantly made on far-field components. CONCLUSIONS: Multielectrode array catheters provide a unique platform for constructing multipolar EGMs. This new EGM may be beneficial for "purifying" local potentials within a complex electrical field, resulting in more accurate voltage and activation maps.

2.
JACC Clin Electrophysiol ; 10(6): 1078-1086, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38703164

RESUMO

BACKGROUND: In patients with persistent atrial fibrillation (PerAF), antiarrhythmic drugs (AADs) are considered a first-line rhythm-control strategy, whereas catheter ablation is a reasonable alternative. OBJECTIVES: This study sought to examine the prevalence, patient characteristics, and clinical outcomes of patients with PerAF who underwent catheter ablation as a first or second-line strategy. METHODS: This multicenter observational study included consecutive patients with PerAF who underwent first-time ablation between January 2020 and September 2021 in 9 medical centers in the United States. Patients were divided into those who underwent ablation as first-line therapy and those who had ablation as second-line therapy. Patient characteristics and clinical outcomes were compared between the groups. RESULTS: A total of 2,083 patients underwent first-time ablation for PerAF. Of these, 1,086 (52%) underwent ablation as a first-line rhythm-control treatment. Compared with patients treated with AADs as first-line therapy, these patients were predominantly male (72.6% vs 68.1%; P = 0.03), with a lower frequency of hypertension (64.0% vs 73.4%; P < 0.001) and heart failure (19.1% vs 30.5%; P < 0.001). During a mean follow-up of 325.9 ± 81.6 days, arrhythmia-free survival was similar between the groups (HR: 1.13; 95% CI: 0.92-1.41); however, patients in the second-line ablation strategy were more likely to continue receiving AAD therapy (41.5% vs 15.9%; P < 0.001). CONCLUSIONS: A first-line ablation strategy for PerAF is prevalent in the United States, particularly in men with fewer comorbidities. More data are needed to identify patients with PerAF who derive benefit from an early intervention strategy.


Assuntos
Antiarrítmicos , Fibrilação Atrial , Ablação por Cateter , Humanos , Fibrilação Atrial/cirurgia , Fibrilação Atrial/tratamento farmacológico , Fibrilação Atrial/epidemiologia , Fibrilação Atrial/terapia , Masculino , Ablação por Cateter/estatística & dados numéricos , Feminino , Pessoa de Meia-Idade , Idoso , Antiarrítmicos/uso terapêutico , Resultado do Tratamento , Estados Unidos/epidemiologia
3.
JACC Clin Electrophysiol ; 9(8 Pt 3): 1668-1680, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37354172

RESUMO

BACKGROUND: Ablation index (AI) is used for guiding therapy during pulmonary vein isolation. However, its potential utility in ventricular myocardium is unknown. OBJECTIVES: This study sought to examine the correlation between AI and lesion dimensions in healthy and infarcted ventricles. METHODS: In ex vivo experiments using healthy swine ventricles, the correlation between AI (400-1,200) and lesion dimensions was examined at fixed power (30 W) and contact force (CF) (15 g). To examine the accuracy of AI in predicting lesion dimensions created by different combinations of ablation parameters, applications with a similar prespecified AI value created using different power (30 vs 40 W), CF (15 vs 25 g) or impedance (130-170 Ω) were created. In in vivo experiments, the correlation between AI and lesion dimensions was examined in healthy and infarcted myocardium. RESULTS: Ex vivo experiments (247 lesions, 36 hearts) showed good correlation between AI and lesion depth (R = 0.93; P < 0.001). However, in vivo experiments (9 healthy swine and 10 infarcted swine) showed moderate correlation in healthy myocardium (R = 0.64; P < 0.01) and poor correlation in infarcted myocardium (R = 0.23; P = 0.61). AI values achieved using different combinations of power, CF, and baseline impedance resulted in different lesion depths: Ablation at 30 W produced deeper lesions compared with 40 W, ablation with CF of 15 g produced deeper lesions compared with CF of 25 g, and ablation at lower impedance produced larger lesions at similar prespecified AI values (P < 0.01 for all). CONCLUSIONS: AI has limited value for guiding ablation in ventricular myocardium, particularly scar. This may be related to small proportional significance of application duration and complex tissue architecture.


Assuntos
Ablação por Cateter , Suínos , Animais , Ablação por Cateter/métodos , Miocárdio/patologia , Ventrículos do Coração/cirurgia , Ventrículos do Coração/patologia , Coração , Impedância Elétrica
4.
Europace ; 25(3): 1135-1143, 2023 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-36635956

RESUMO

AIMS: To test the hypothesis that the dispersive patch (DP) location does not significantly affect the current distribution around the catheter tip during radiofrequency catheter ablation (RFCA) but may affect lesions size through differences in impedance due to factors far from the catheter tip. METHODS: An in silico model of RFCA in the posterior left atrium and anterior right ventricle was created using anatomic measurements from patient thoracic computed tomography scans and tested the effect of anterior vs. posterior DP locations on baseline impedance, myocardial power delivery, radiofrequency current path, and predicted lesion size. RESULTS: For posterior left atrium ablation, the baseline impedance, total current delivered, current distribution, and proportion of power delivered to the myocardium were all similar with both anterior and posterior DP locations, resulting in similar RFCA lesion sizes (< 0.2 mm difference). For anterior right ventricular (RV) ablation, an anterior DP location resulted in slightly higher proportion of power delivered to the myocardium and lower baseline impedance leading to slightly larger RFCA lesions (0.6 mm deeper and 0.8 mm wider). CONCLUSIONS: An anterior vs. posterior DP location will not meaningfully affect RFCA for posterior left atrial ablation, and the slightly larger lesions predicted with anterior DP location for anterior RV ablation are of unclear clinical significance.


Assuntos
Ablação por Cateter , Átrios do Coração , Humanos , Átrios do Coração/diagnóstico por imagem , Átrios do Coração/cirurgia , Miocárdio/patologia , Tomografia Computadorizada por Raios X , Ablação por Cateter/efeitos adversos , Ablação por Cateter/métodos , Simulação por Computador
5.
Circ Arrhythm Electrophysiol ; 16(1): e011321, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36595639

RESUMO

BACKGROUND: Endocardial bipolar voltage amplitude is largely derived from endocardial and subendocardial wall layers. This may result in situations of low bipolar voltage amplitude despite the presence of mid-myocardial including epicardial (ie, intramural-epicardial) viable myocardium. This study examined the utility of endocardial unipolar voltage mapping for detection of viable intramural-epicardial atrial myocardium. METHODS: In 15 swine, an atrial intercaval ablation line with an intentional gap was created. Animals survived for 6 to 8 weeks before electroanatomical mapping followed by sacrifice. Gaps were determined by the presence of electrical conduction and classified based on the histopathologiclly layer(s) of viable myocardium into the following: (1) transmural, (2) endocardial, and (3) intramural-epicardial. Voltage data from healthy, scar, and gap points were exported into excel. The sensitivity and specificity of bipolar and unipolar voltage amplitude to detect intramural-epicardial gaps were compared using receiver operating characteristic analysis. RESULTS: In 9 of 15 (60%) swine, a focal ablation gap was detected in the intercaval line, while in the remainder 6 of 15 (40%), the line was complete without gaps. Gaps were classified into transmural (n=3), endocardial (n=3), or intramural-epicardial (n=3). Intramural-epicardial gaps were characterized by very low bipolar voltage amplitude that was similar to areas with transmural scar (P=0.91). In comparison, unipolar voltage amplitude in intramural-epicardial gaps was significantly higher compared to transmural scar (P<0.001). Unipolar voltage amplitude had higher sensitivity (93% versus 14%, respectively) and similar specificity (95% versus 98%, respectively) to bipolar voltage for detection of intramural-epicardial gaps. CONCLUSIONS: Atrial unipolar voltage mapping may be a useful technique for identifying viable intramural-epicardial myocardium in patients with endocardial scar.


Assuntos
Fibrilação Atrial , Ablação por Cateter , Taquicardia Ventricular , Animais , Suínos , Cicatriz , Miocárdio/patologia , Endocárdio , Ablação por Cateter/métodos
6.
J Cardiovasc Dev Dis ; 9(10)2022 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-36286288

RESUMO

Background: Baseline impedance, radiofrequency current, and impedance drop during radiofrequency catheter ablation are thought to predict effective lesion formation. However, quantifying the contributions of local versus remote impedances provides insights into the limitations of indices using those parameters. Methods: An in silico model of left atrial radiofrequency catheter ablation was used based on human thoracic measurements and solved for (1) initial impedance (Z), (2) percentage of radiofrequency power delivered to the myocardium and blood (3) total radiofrequency current, (4) impedance drop during heating, and (5) lesion size after a 25 W−30 s ablation. Remote impedance was modeled by varying the mixing ratio between skeletal muscle and fat. Local impedance was modeled by varying insertion depth of the electrode (ID). Results: Increasing the remote impedance led to increased baseline impedance, lower system current delivery, and reduced lesion size. For ID = 0.5 mm, Z ranged from 115 to 132 Ω when fat percentage varied from 20 to 80%, resulting in a decrease in the RF current from 472 to 347 mA and a slight decrease in lesion size from 5.6 to 5.1 mm in depth, and from 9.2 to 8.0 mm in maximum width. In contrast, increasing the local impedance led to lower system current but larger lesions. For a 50% fat−muscle mixture, Z ranged from 118 to 138 Ω when ID varied from 0.3 to 1.9 mm, resulting in a decrease in the RF current from 463 to 443 mA and an increase in lesion size, from 5.2 up to 7.5 mm in depth, and from 8.4 up to 11.6 mm in maximum width. In cases of nearly identical Z but different contributions of local and remote impedance, markedly different lesions sizes were observed despite only small differences in RF current. Impedance drop better predicted lesion size (R2 > 0.93) than RF current (R2 < 0.1). Conclusions: Identical baseline impedances and observed RF currents can lead to markedly different lesion sizes with different relative contributions of local and remote impedances to the electrical circuit. These results provide mechanistic insights into the advantage of measuring local impedance and identifies potential limitations of indices incorporating baseline impedance or current to predict lesion quality.

7.
JACC Clin Electrophysiol ; 8(4): 498-510, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35450605

RESUMO

OBJECTIVES: This study sought to examine the effect of the return electrode's surface area on bipolar RFA lesion size. BACKGROUND: Bipolar radiofrequency ablation (RFA) is typically performed between 2 3.5-mm tip catheters serving as active and return electrodes. We hypothesized that increasing the surface area of the return electrode would increase lesion dimensions by reducing the circuit impedance, thus increasing the current into a larger tissue volume enclosed between the electrodes. METHODS: In step 1, ex vivo bipolar RFA was performed between 3.5-mm and custom-made return electrodes with increasing surface areas (20, 80, 180 mm2). In step 2, ex vivo bipolar RFA was performed between 3.5-mm and 3.5-mm or 8-mm electrode catheters positioned perpendicular or parallel to the tissue. In step 3, in vivo bipolar RFA was performed between 3.5-mm and either 3.5-mm or 8-mm parallel electrode at the: 1) left ventricular summit; 2) interventricular septum; and 3) healed anterior infarction. RESULTS: In step 1, increasing the surface area of the return electrode resulted in lower circuit impedance (R = -0.65; P < 0.001), higher current (R = +0.80; P < 0.001), and larger lesion volume (R = +0.88; P < 0.001). In step 2, an 8-mm return electrode parallel to tissue produced larger and deeper lesions compared with a 3.5-mm return electrode (P = 0.014 and P = 0.02). Similarly, in step 3, compared with a 3.5-mm, bipolar RFA with an 8-mm return electrode produced larger (volume: 1,525 ± 871 mm3 vs 306 ± 310 mm3, respectively; P < 0.001) and more transmural lesions (88% vs 0%; P < 0.001). CONCLUSIONS: Bipolar RFA using an 8-mm return electrode positioned parallel to the tissue produces larger lesions in comparison with a 3.5-mm return electrode.


Assuntos
Ablação por Cateter , Ablação por Cateter/métodos , Eletrodos , Desenho de Equipamento , Ventrículos do Coração/cirurgia , Humanos
8.
JACC Clin Electrophysiol ; 6(11): 1452-1464, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-33121675

RESUMO

OBJECTIVES: This study sought to investigate the sensitivity of electroanatomical mapping (EAM) to detect scar as identified by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR). BACKGROUND: Previous studies have shown correlation between low voltage electrogram amplitude and myocardial scar. However, voltage amplitude is influenced by the distance between the scar and the mapping surface and its extent. The aim of this study is to examine the reliability of low voltage EAM as a surrogate for myocardial scar using LGE-derived scar as the reference. METHODS: Twelve swine underwent anterior wall infarction by occlusion of the left anterior descending artery (LAD) (n = 6) or inferior wall infarction by occlusion of the left circumflex artery (LCx) (n = 6). Subsequently, animals underwent CMR and EAM using a multielectrode mapping catheter. CMR characteristics, including wall thickness, LGE location and extent, and EAM maps, were independently analyzed, and concordance between voltage maps and CMR characteristics was assessed. RESULTS: LGE volume was similar between the LCx and LAD groups (8.5 ± 2.2 ml vs. 8.3 ± 2.5 ml, respectively; p = 0.852). LGE scarring in the LAD group was more subendocardial, affected a larger surface area, and resulted in significant wall thinning (4.88 ± 0.43 mm). LGE scarring in the LCx group extended from the endocardium to the epicardium with minimal reduction in wall thickness (scarred: 5.4 ± 0.67 mm vs. remote: 6.75 ± 0.38 mm). In all the animals in the LAD group, areas of low voltage corresponded with LGE and wall thinning, whereas only 2 of 6 animals in the LCx group had low voltage areas on EAM. Bipolar and unipolar voltage amplitudes were higher in thick inferior walls in the LCx group than in thin anterior walls in the LAD group, despite a similar LGE volume. CONCLUSIONS: Discordances between LGE-detected scar areas and low voltage areas by EAM highlighted the limitations of the current EAM system to detect scar in thick myocardial wall regions.


Assuntos
Cicatriz , Gadolínio , Animais , Cicatriz/diagnóstico por imagem , Cicatriz/patologia , Meios de Contraste , Técnicas Eletrofisiológicas Cardíacas , Infarto , Imageamento por Ressonância Magnética , Reprodutibilidade dos Testes , Suínos
9.
JACC Clin Electrophysiol ; 6(8): 973-985, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32819533

RESUMO

OBJECTIVES: The goal of this study was to compare lesion durability between high-power short-duration (HP-SD) and moderate-power moderate-duration (MP-MD) ablation strategies. BACKGROUND: HP-SD radiofrequency ablation (RFA) was developed to improve pulmonary vein isolation (PVI) by reducing the effect of catheter instability inherent to MP-MD ablation strategies. However, its long-term effect on lesion durability for the treatment of atrial fibrillation is unknown. METHODS: Patients with atrial fibrillation (n = 112) underwent PVI using HP-SD ablation (45 to 50 W, 8 to 15 s) with contact force-sensing open irrigated catheter. Cavotricuspid isthmus, mitral annular, and roof lines were permitted. A control group (n = 112) underwent ablation using MP-MD ablation (20 to 40 W, 20 to 30 s) with similar technology. Chronic PV reconnection was examined in patients who required a redo procedure (HP-SD ablation, n = 18; MP-MD ablation, n = 23). RESULTS: The rate of PVI at the completion of the initial encirclement was similar between the HP-SD and MP-MD ablation strategies (90.2% vs. 83.0%; p = 0.006). The HP-SD strategy required shorter RFA time (17.2 ± 3.4 min vs. 31.1 ± 5.6 min; p < 0.001). The incidence of chronic PV reconnection was lower with HP-SD ablation (16.6% vs. 52.2%; p = 0.03). Areas of chronic reconnection were associated with catheter motion ≥1 mm for ≥50% application duration. In a higher proportion of HP-SD applications, catheter motion was <1 mm during ≥50% duration (88.6% vs. 72.8%; p < 0.001), allowing energy delivery with greater stability. Both ablation strategies were effective for cavotricuspid isthmus; however, the HP-SD strategy was less effective for mitral annular lines, requiring ablation at lower power for longer duration to avoid steam pops. CONCLUSIONS: HP-SD ablation may improve PVI durability, and it shortens RFA time. However, ablation in thicker myocardium often requires lower power applied for longer duration, allowing deeper lesions without tissue overheating.


Assuntos
Fibrilação Atrial , Ablação por Cateter , Veias Pulmonares , Ablação por Radiofrequência , Fibrilação Atrial/cirurgia , Humanos , Veias Pulmonares/cirurgia , Resultado do Tratamento
10.
Circ Arrhythm Electrophysiol ; 13(6): e008580, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32372696

RESUMO

BACKGROUND: Pulsed field ablation (PFA) is a nonthermal energy that may provide safety advantages over radiofrequency ablation (RFA). One-shot PFA catheters have been developed for pulmonary vein isolation, but they do not permit flexible lesion sets. This study investigated a novel lattice-tip catheter designed for focal RFA or PFA ablation. METHODS: The effects of PFA (biphasic, 24 amperes) were investigated in 25 swine using a lattice-tip catheter and system (Affera Inc). Step 1 (n=14) examined the feasibility to create atrial line of block and described its acute effects on the phrenic nerve and esophagus. Step 2 (n=7) examined the subacute effects of PFA on block durability, phrenic nerve, and esophagus ≥2 weeks. Step 3 compared the effects of PFA and RFA on the esophagus using a mechanical deviation model approximating the esophagus to the right atrium (n=4) and by direct ablation within its lumen (n=4). The effects of endocardial PFA and RFA on the phrenic nerve were also compared (n=10). Histological analysis was performed. RESULTS: PFA produced acute block in 100% of lines, achieved with 2.1 (1.3-3.2) applications/cm line. Histological analysis following (35 [18-37]) days showed 100% transmurality (thickness range 0.4-3.4 mm) with a lesion width of 19.4 (10.9-27.4 mm). PFA selectively affected cardiomyocytes but spared blood vessels and nervous tissue. PFA applied from the posterior atria (23 [21-25] applications) to the approximated esophagus (6 [4.5-14] mm) produced transmural lesions without esophageal injury. PFA (16.5 [15-18] applications) applied inside the esophageal lumen produced mild edema compared with RFA (13 [12-14] applications) which produced epithelial ulcerations. PFA resulted in no or transient stunning of the phrenic nerve (<5 minutes) without histological changes while RFA produced paralysis. CONCLUSIONS: PFA using a lattice-tip ablation catheter for focal ablation produced durable atrial lesions and showed lower vulnerability to esophageal or phrenic nerve damage compared with RFA.


Assuntos
Cateterismo Cardíaco/instrumentação , Cateteres Cardíacos , Ablação por Cateter/instrumentação , Eletrodos , Átrios do Coração/cirurgia , Animais , Cateterismo Cardíaco/efeitos adversos , Ablação por Cateter/efeitos adversos , Desenho de Equipamento , Esôfago/lesões , Esôfago/patologia , Átrios do Coração/patologia , Átrios do Coração/fisiopatologia , Traumatismos dos Nervos Periféricos/etiologia , Traumatismos dos Nervos Periféricos/patologia , Nervo Frênico/lesões , Nervo Frênico/patologia , Sus scrofa , Fatores de Tempo
11.
Europace ; 22(3): 440-449, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31985784

RESUMO

AIMS: Multielectrode mapping catheters can be advantageous for identifying surviving myocardial bundles in scar. This study aimed to evaluate the utility of a new multielectrode catheter with increased number of small and closely spaced electrodes for mapping ventricles with healed infarction. METHODS AND RESULTS: In 12 swine (four healthy and eight with infarction), the left ventricle was mapped with investigational (OctarayTM) and standard (PentarayTM) multielectrode mapping catheters. The investigational catheter has more electrodes (48 vs. 20), each with a smaller surface area (0.9 vs. 2.0 mm2) and spacing is fixed at 2 mm (vs. 2-6-2 mm). Electrogram (EGM) characteristics, mapping efficiency and scar description were compared between the catheters and late gadolinium enhancement (LGE). Electrogram acquisition rate was faster with the investigational catheter (814 ± 126 vs. 148 ± 58 EGM/min, P = 0.02) resulting in higher density maps (38 ± 10.3 vs. 10.1 ± 10.4 EGM/cm2, P = 0.02). Bipolar voltage amplitude was similar between the catheters in normal and infarcted myocardium (P = 0.265 and P = 0.44) and the infarct surface area was similar between the catheters (P = 0.12) and corresponded to subendocardial LGE. The investigational catheter identified a higher proportion of near-field local abnormal ventricular activities within the low-voltage area (53 ± 16% vs. 34 ± 16%, P = 0.03) that were considered far-field EGMs by the standard catheter. The investigational catheter was also advantageous for mapping haemodymically non-tolerated ventricular tachycardias due to its higher acquisition rate (P < 0.001). CONCLUSION: A novel multielectrode mapping catheter with higher number of small, and closely spaced electrodes increases the mapping speed, EGM density and the ability to recognize low amplitude near-field EGMs in ventricles with healed infarction.


Assuntos
Ablação por Cateter , Taquicardia Ventricular , Animais , Catéteres , Cicatriz/patologia , Meios de Contraste , Gadolínio , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/patologia , Suínos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/patologia
12.
JACC Clin Electrophysiol ; 6(1): 83-93, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31971910

RESUMO

OBJECTIVES: The goal of this study was to examine the safety and efficacy of radiofrequency ablation (RFA) with irrigated catheters operated in a temperature-controlled mode for ventricular ablation. BACKGROUND: Techniques to increase RFA dimensions are associated with higher risk for steam-pops. A novel irrigated catheter with circumferential thermocouples embedded in its ablation surface provides real-time surface temperature data. This study hypothesized that RFA operated in a temperature-controlled mode may allow maximizing lesion dimensions while reducing the occurrence of steam-pops. METHODS: RFA with an irrigated catheter incorporating surface thermocouples was examined in 6 swine thigh muscle preparations and 15 beating ventricles at higher (50 W/60 s, Tmax50oC) and lower (50 W/60 s, Tmax45oC) temperature limits. Biophysical properties, lesion dimensions, and steam-pop occurrence were compared versus RFA with a standard catheter operated in power-control mode at higher (50 W/60 s) and lower (40W/60 s) power, and additionally at high power with half-normal saline (50 W/60 s). RESULTS: In the thigh muscle preparation, lesion depth and width were similar between all groups (p = 0.90 and p = 0.17, respectively). Steam-pops were most frequent with power-controlled ablation at 50 W/60 s (82%) and least frequent with temperature-controlled ablation at 50 W/60 s, Tmax45oC (0%; p < 0.001). In the beating ventricle, lesion depth was comparable between all RFA settings (p = 0.09). Steam-pops were most frequent using power-controlled ablation at 50 W/60 s (37%) and least frequent with temperature-controlled ablation at 50 W/60 s, Tmax45oC (7%; p < 0.001). Half-normal saline had no incremental effect on lesion dimensions at 50 W in either the thigh muscle or the beating heart. CONCLUSIONS: RFA using a novel irrigated catheter with surface thermocouples operated in a temperature-controlled mode can maximize lesion dimensions while reducing the risk for steam-pops.


Assuntos
Ablação por Cateter , Catéteres , Ventrículos do Coração/cirurgia , Irrigação Terapêutica/instrumentação , Animais , Ablação por Cateter/efeitos adversos , Ablação por Cateter/instrumentação , Ablação por Cateter/métodos , Ablação por Cateter/normas , Desenho de Equipamento , Ventrículos do Coração/patologia , Suínos , Temperatura
13.
Circ Arrhythm Electrophysiol ; 12(11): e007661, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31707809

RESUMO

BACKGROUND: Ventricular tachycardia ablation is often limited by insufficient lesion creation. A novel radiofrequency catheter with an expandable lattice electrode has a larger surface area capable of delivering higher currents at a lower density to potentially increase lesion dimensions without overheating. METHODS: This 8F bidirectional irrigated catheter (Sphere-9, Affera Inc) has a 9 mm spherical lattice tip ("lattice") with an effective surface area 10-fold larger than standard linear catheters. Nine surface thermocouples provide temperature feedback to a proprietary high-current generator operating in a temperature-controlled mode. Ex vivo phase: in 11 bovine hearts, unipolar ablation at 30, 60, and 120 seconds was compared between the lattice (Tmax60°C) and a standard linear irrigated-tip catheter (40 W) at contact force of 10 g. In 5 porcine hearts, bipolar ablation was compared between the catheters (Tmax60°C versus 40 W; 60 seconds). In vivo phase: in 9 swine, ventricular ablation at Tmax60°C versus 40 W was performed for 60 seconds. In addition, direct tissue temperature at 3- and 7-mm tissue depth was measured in a thigh muscle preparation. RESULTS: Ex vivo: lattice produced deeper lesions at 30, 60, and 120 seconds application duration (6.7±1.3 versus 4.8±1.2 mm; 8.3±1.4 versus 5.4±0.8 mm; 10.0±1.6 versus 6.1±1.6 mm, respectively, P≤0.001 for all). Bipolar lesions were deeper (15.8±4.1 versus 10.5±1.4 mm, P<0.001) and more likely to be transmural (80% versus 0%, P=0.002). In vivo: lattice produced deeper lesions (10.5±1.4 versus 6.5±0.8 mm, P≤0.001). Tissue temperature at 7 mm was higher with the lattice (+15.1±2.4°C; P<0.001). The steam-pop occurrence was lower with the lattice (total: 4% versus 18%, P=0.02; in vivo 0% versus 14.2%, P=0.13). CONCLUSIONS: This novel radiofrequency system produces larger ventricular lesions compared with standard irrigated catheters and at a lower risk of tissue overheating. This may improve the efficacy of ventricular tachycardia ablation procedures while reducing the number of applications and procedural duration.


Assuntos
Ablação por Cateter/instrumentação , Sistema de Condução Cardíaco/cirurgia , Frequência Cardíaca/fisiologia , Taquicardia Ventricular/cirurgia , Irrigação Terapêutica/instrumentação , Animais , Bovinos , Modelos Animais de Doenças , Desenho de Equipamento , Sistema de Condução Cardíaco/fisiopatologia , Suínos , Taquicardia Ventricular/fisiopatologia
14.
Circ Arrhythm Electrophysiol ; 12(10): e007879, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31597477

RESUMO

BACKGROUND: In infarct-related ventricular tachycardia (VT), the circuit often corresponds to a location characterized by activation slowing during sinus rhythm (SR). However, the relationship between activation slowing during SR and vulnerability for reentry and correlation to components of the VT circuit are unknown. This study examined the relationship between activation slowing during SR and vulnerability for reentry and correlated these areas with components of the circuit. METHODS: In a porcine model of healed infarction, the spatial distribution of endocardial activation velocity was compared between SR and VT. Isthmus sites were defined using activation and entrainment mapping as areas exhibiting diastolic activity within the circuit while bystanders were defined as areas displaying diastolic activity outside the circuit. RESULTS: Of 15 swine, 9 had inducible VT (5.2±3.0 per animal) while in 6 swine VT could not be induced despite stimulation from 4 RV and LV sites at 2 drive trains with 6 extra-stimuli down to refractoriness. Infarcts with VT had a greater magnitude of activation slowing during SR. A minimal endocardial activation velocity cutoff ≤0.1 m/s differentiated inducible from noninducible infarctions (P=0.015). Regions of maximal endocardial slowing during SR corresponded to the VT isthmus (area under curve=0.84 95% CI, 0.78-0.90) while bystander sites exhibited near-normal activation during SR. VT circuits were complex with 41.7% exhibiting discontinuous propagation with intramural bridges of slow conduction and delayed quasi-simultaneous endocardial activation. Regions forming the VT isthmus borders had faster activation during SR while regions forming the inner isthmus were activated faster during VT. CONCLUSIONS: Endocardial activation slowing during SR may differentiate infarctions vulnerable for VT from those less vulnerable for VT. Sites of slow activation during SR correspond to sites forming the VT isthmus but not to bystander sites.


Assuntos
Cicatriz/fisiopatologia , Endocárdio/fisiopatologia , Sistema de Condução Cardíaco/fisiopatologia , Frequência Cardíaca/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Infarto do Miocárdio/fisiopatologia , Taquicardia Ventricular/etiologia , Animais , Mapeamento Potencial de Superfície Corporal/métodos , Modelos Animais de Doenças , Ventrículos do Coração/fisiopatologia , Infarto do Miocárdio/complicações , Infarto do Miocárdio/diagnóstico , Suínos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/fisiopatologia
15.
JACC Clin Electrophysiol ; 5(8): 920-931, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31439293

RESUMO

OBJECTIVES: This study sought to characterize the histopathological features of radiofrequency ablation (RFA) in heterogeneous ventricular scar in comparison to those in healthy myocardium. BACKGROUND: The histopathological features of RFA have been studied largely in normal myocardium. However, its effect on clinically relevant heterogeneous scar is not well understood. METHODS: Five swine with chronic infarction underwent RFA using 35-W, 45-s, 10-20 g (Biosense Webster, Irwindale, California) in heterogenous scar tissue (voltage ≤1.5 mV) and healthy myocardium (≥3.0 mV). The location of each application was marked using the electroanatomical mapping system. Histological sections at intervals of 0.5 mm with hematoxylin and eosin and Masson's trichrome stained intervals were created. A pathologist blinded to the myocardium type characterized the extent of RF injury in cellular, extracellular, and vascular structures. RESULTS: In healthy myocardium, 23 of 23 lesions (100%) were well demarcated and could be precisely measured (width: 11.3 ± 3.3 mm; depth: 7.3 ± 2.0 mm). In scar tissue, only 3 of 30 lesions (10%) were identified, and none could be measured due to a lack of defined borders. Lesions in healthy myocardium had a distinctive architecture showing a coagulative necrosis core surrounded by an outer rim of contraction band necrosis. Lesions in scar had ill-defined tissue injury without a distinct architecture. In all ablated regions, viable myocytes remained interspersed between necrotic myocytes exhibiting characteristics of both coagulative and contraction band necrosis. Connective tissue was more resistant to thermal injury in comparison to cardiomyocytes. CONCLUSIONS: RFA in scarred myocardium results in irregular tissue injury and unpredictable effect on surviving cardiomyocytes. This may be related to biophysical differences between healthy and scarred myocardium.


Assuntos
Ablação por Cateter , Cicatriz/patologia , Ventrículos do Coração , Animais , Ventrículos do Coração/patologia , Ventrículos do Coração/cirurgia , Masculino , Infarto do Miocárdio/patologia , Infarto do Miocárdio/cirurgia , Miocárdio/patologia , Suínos , Taquicardia Ventricular/patologia , Taquicardia Ventricular/cirurgia
16.
Circ Arrhythm Electrophysiol ; 12(6): e007336, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31113232

RESUMO

Background Radiofrequency ablation of intramural ventricular substrate is often limited by insufficient tissue penetration despite high energy settings. As lesion dimensions have a direct and negative relationship to impedance, reducing the baseline impedance may increase the ablation effect on deep ventricular tissue. Methods This study included 16 patients with ventricular tachycardia or frequent ventricular premature complexes refractory to ablation with irrigated catheters. After a failed response to radiofrequency ablation, impedance was modulated by adding or repositioning return patches in an attempt to decrease the circuit impedance. Ablation was repeated at a similar location and power settings, and the effect on arrhythmia suppression and adverse effects were evaluated. Results Six patients with idiopathic ventricular premature complexes originating from the left ventricular summit (n=4) or papillary muscles (n=2), 6 patients with noninfarct related ventricular tachycardia and 4 patients with infarct-related ventricular tachycardia had unsuccessful response to radiofrequency ablation at critical sites (number of applications: 10.4±3.1, power: 42.3±2.9 W, duration: 55.3±25.5 seconds, impedance reduction: 14.6±3.5 Ω, low-ionic solution was used in 81.25%). Modulating the return patches resulted in reduced baseline impedance (111.7±8.2 versus 134.7±6.6 Ω, P<0.0001), increased current output (0.6±0.02 versus 0.56±0.02 Amp; P<0.0001) and greater impedance drop (16.8±3.0 Ω, P<0.001). Repeat ablation at similar locations had a successful effect in 12 out of 16 (75.0%) patients. During a follow-up duration of 13±5 months, 10 out of 12 (83.3%) patients remained free of arrhythmia recurrence. The frequency of steam pops was similar between the higher and lower baseline impedance settings (7.1 versus 8.2%; P=0.74). Conclusions In patients with deep ventricular substrate, reducing the baseline impedance is a simple, safe, and effective technique for increasing the effect of radiofrequency ablation. However, its combination with low-ionic solutions may increase the risk for steam pops and neurological events.


Assuntos
Ablação por Cateter/instrumentação , Ventrículos do Coração/cirurgia , Taquicardia Ventricular/cirurgia , Complexos Ventriculares Prematuros/cirurgia , Potenciais de Ação , Idoso , Ablação por Cateter/efeitos adversos , Impedância Elétrica , Feminino , Frequência Cardíaca , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Intervalo Livre de Progressão , Recidiva , Estudos Retrospectivos , Fatores de Risco , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/fisiopatologia , Fatores de Tempo , Complexos Ventriculares Prematuros/diagnóstico , Complexos Ventriculares Prematuros/fisiopatologia
17.
Circ Arrhythm Electrophysiol ; 12(4): e007090, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30943762

RESUMO

BACKGROUND: High-current short-duration radiofrequency energy delivery has potential advantages for cardiac ablation. However, this strategy is limited by high current density and narrow safety-to-efficacy window. The objective of this study was to examine a novel strategy for radiofrequency energy delivery using a new electrode design capable of delivering high power at a low current density to increase the therapeutic range of radiofrequency ablation. METHODS: The Sphere9 is an expandable spheroid-shaped lattice electrode design with an effective surface area 10-fold larger than standard irrigated electrodes (lattice catheter). It incorporates 9 surface temperature sensors with ablation performed in a temperature-controlled mode. Phase I: in 6 thigh muscle preparations, 2 energy settings for atrial ablation were compared between the lattice and irrigated-tip catheters (low-energy: Tmax75°C/5 s versus 25 W/20 s; high-energy: Tmax75°C/7 s versus 30 W/20 s). Phase II: in 8 swine, right atrial lines were created in the posterior and lateral walls using low- and high-energy settings, respectively. Phase III: the safety, efficacy, and durability at 30 days were evaluated by electroanatomical mapping and histopathologic analysis. RESULTS: In the thigh model, the lattice catheter resulted in wider lesions at both low- and high-energy settings (18.7±3.3 versus 12.2±1.7 mm, P<0.0001; 19.4±2.4 versus 12.3±1.7 mm, P<0.0001). Atrial lines created with the lattice were wider (posterior: 14.7±3.4 versus 9.2±4.0 mm, P<0.0001; lateral: 15.8±4.2 versus 5.7±4.2 mm, P<0.0001) and required 85% shorter ablation time (12.4 versus 79.8 s/cm-line). While current squared (I2) was higher with Sphere9 (7.0±0.04 versus 0.2±0.002 A2; P<0.0001), the current density was lower (9.6±0.9 versus 16.9±0.09 mA/mm2; P<0.0001). At 30 days, 100% of ablation lines created with the lattice catheter remained contiguous compared with only 14.3% lines created with a standard irrigated catheter. This was achieved without steam pops or collateral tissue damage. CONCLUSIONS: In this preclinical model, a novel, high-current low-density radiofrequency ablation strategy created contiguous and durable ablation lines in significantly less ablation time and a comparable safety profile.


Assuntos
Eletrodos , Átrios do Coração/cirurgia , Ablação por Radiofrequência/instrumentação , Animais , Desenho de Equipamento , Segurança de Equipamentos , Modelos Animais , Estudos Prospectivos , Suínos , Coxa da Perna/cirurgia
18.
J Cardiovasc Electrophysiol ; 30(5): 749-757, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30723994

RESUMO

INTRODUCTION: Multielectrode mapping catheters improve the ability to map within the heterogeneous scar. A novel Octaray catheter with eight spines and 48 electrodes may further improve the speed and resolution of atrial mapping. The aims of this study were to (1) establish the Octaray's baseline mapping performance and electrogram (EGM) characteristics in healthy atria and to (2) determine its utility for identifying gaps in a swine model of atrial ablation lines. METHODS AND RESULTS: The right atria of eight healthy swine were mapped with Octaray and Pentaray catheters (Biosense Webster, Irvine, CA) before and after the creation of ablation lines with intentional gaps. Baseline mapping characteristics including EGM amplitude, duration, number of EGMs, and mapping time were compared. Postablation maps were created and EGM characteristics of continuous lines and gaps were correlated with pathology. Compared with Pentaray, the Octaray collected more EGMs per map (2178 ± 637 vs 1046 ± 238; P < 0.001) at a shorter mapping duration (3.2 ± 0.79 vs 6.9 ± 2.67 minutes; P < 0.001). In healthy atria, the Octaray recorded lower bipolar voltage amplitude (1.96 ± 1.83 mV vs 2.41 ± 1.92 mV; P < 0.001) while ablation gaps were characterized by higher voltage amplitude (1.24 ± 1.12 mV vs 1.04 ± 1.27 mV; P < 0.001). Ablation gaps were similarly identified by both catheters (P = 1.0). The frequency of "false gaps," defined as intact ablation lines with increased voltage amplitude was more common with Pentaray (6 vs 2) and resulted from erroneous annotation of far-field EGMs. CONCLUSION: The Octaray increases the mapping speed and density compared with the Pentaray catheter. It is as sensitive for identifying ablation gaps and more specific for mapping intact ablation lines.


Assuntos
Potenciais de Ação , Cateteres Cardíacos , Ablação por Cateter , Técnicas Eletrofisiológicas Cardíacas/instrumentação , Átrios do Coração/cirurgia , Frequência Cardíaca , Microeletrodos , Animais , Desenho de Equipamento , Átrios do Coração/fisiopatologia , Valor Preditivo dos Testes , Sus scrofa , Fatores de Tempo
19.
Circ Arrhythm Electrophysiol ; 12(1): e006933, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30606034

RESUMO

BACKGROUND: The mitral isthmus is the critical element of perimitral reentrant tachycardias. Prolongation in transisthmus conduction time and differential pacing techniques are commonly used to determine block. However, these may not distinguish block from slow conduction or conduction via epicardial bridging connections. The aim of this study was to examine these standard criteria for mitral line block with endocardial and epicardial activation mapping. METHODS: In 56 patients, posterior mitral line was performed using radiofrequency ablation. Conduction block was defined as transisthmus time (≥100 ms) and reversal of coronary sinus activation during pacing from the left atrial appendage. These results were compared with high-resolution activation mapping (Rhythmia) of the endocardium and epicardium via the coronary sinus. RESULTS: Mitral block determined by pacing was achieved in 51 out of 56 (91%) patients. In 11 out of 51 (21.6%), activation mapping demonstrated residual endocardial (3/11; 27.2%) or epicardial (8/11; 72.7%) connections. Epicardial bridging connections were distant from the line (2.4±1.6 cm), inserting laterally at the proximal-middle coronary sinus and septally at the left atrial ridge. Patients with residual conduction were prone to complex circuits involving the epicardium (7/11; 63.6%). Mitral line block was achieved in 75% by targeting these insertion site(s). The transisthmus conduction time had limited predictive value for distinguishing block from pseudoblock. CONCLUSIONS: Standard criteria for posterior mitral line block may not distinguish block from pseudoblock. In particular, epicardial bridging connections can result in prolonged transisthmus conduction time and reversal in coronary sinus activation to falsely suggest block. These connections are a frequent cause for complex circuits, and their insertion site(s) can be targeted for ablation.


Assuntos
Fibrilação Atrial/cirurgia , Flutter Atrial/cirurgia , Seio Coronário/cirurgia , Frequência Cardíaca , Valva Mitral/cirurgia , Veias Pulmonares/cirurgia , Ablação por Radiofrequência/métodos , Potenciais de Ação , Idoso , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/fisiopatologia , Flutter Atrial/diagnóstico , Flutter Atrial/fisiopatologia , Estimulação Cardíaca Artificial , Seio Coronário/fisiopatologia , Técnicas Eletrofisiológicas Cardíacas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/fisiopatologia , Estudos Prospectivos , Veias Pulmonares/fisiopatologia , Ablação por Radiofrequência/efeitos adversos , Fatores de Tempo , Resultado do Tratamento
20.
PLoS One ; 13(10): e0205188, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30296291

RESUMO

Visualization of the complex 3D architecture of myocardial scar could improve guidance of radio-frequency ablation in the treatment of ventricular tachycardia (VT). In this study, we sought to develop a framework for 3D holographic visualization of myocardial scar, imaged using late gadolinium enhancement (LGE), on the augmented reality HoloLens. 3D holographic LGE model was built using the high-resolution 3D LGE image. Smooth endo/epicardial surface meshes were generated using Poisson surface reconstruction. For voxel-wise 3D scar model, every scarred voxel was rendered into a cube which carries the actual resolution of the LGE sequence. For surface scar model, scar information was projected on the endocardial surface mesh. Rendered layers were blended with different transparency and color, and visualized on HoloLens. A pilot animal study was performed where 3D holographic visualization of the scar was performed in 5 swines who underwent controlled infarction and electroanatomic mapping to identify VT substrate. 3D holographic visualization enabled assessment of the complex 3D scar architecture with touchless interaction in a sterile environment. Endoscopic view allowed visualization of scar from the ventricular chambers. Upon completion of the animal study, operator and mapping specialist independently completed the perceived usefulness questionnaire in the six-item usefulness scale. Operator and mapping specialist found it useful (usefulness rating: operator, 5.8; mapping specialist, 5.5; 1-7 scale) to have scar information during the intervention. HoloLens 3D LGE provides a true 3D perception of the complex scar architecture with immersive experience to visualize scar in an interactive and interpretable 3D approach, which may facilitate MR-guided VT ablation.


Assuntos
Ablação por Cateter/métodos , Cicatriz/diagnóstico por imagem , Holografia/métodos , Infarto do Miocárdio/complicações , Taquicardia Ventricular/cirurgia , Animais , Cicatriz/etiologia , Cicatriz/cirurgia , Meios de Contraste/administração & dosagem , Modelos Animais de Doenças , Endoscopia/métodos , Mapeamento Epicárdico , Estudos de Viabilidade , Gadolínio/administração & dosagem , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/patologia , Ventrículos do Coração/cirurgia , Humanos , Imageamento por Ressonância Magnética/métodos , Projetos Piloto , Suínos , Taquicardia Ventricular/etiologia , Taquicardia Ventricular/patologia
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