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Henry Halperin

Publications and source records attributed to Henry Halperin.

At least 19 recordsLinked to original sources
PubMed2006

Long-term single procedure efficacy of catheter ablation of atrial fibrillation.

BACKGROUND: Two important limitations of the data regarding the outcomes of catheter ablation of atrial fibrillation (AF) are the short-term follow-up used in most published studies and the lack of single-procedure outcomes. OBJECTIVE: The objective was to report the long-term single-procedure outcomes at our center. MATERIALS AND METHODS: The patient population was comprised of 200 consecutive patients who underwent ablation (133 men; age 56 +/- 11 years). Atrial fibrillation was paroxysmal in 92 (46%). Success was defined as absence of symptomatic AF, off antiarrhythmic drug (AAD) after a single procedure. RESULTS: After a follow-up of 26 +/- 11 months, the single-procedure long-term success rate was 28% with an additional 7% of patients demonstrating improvement. After including repeat procedures in 64 patients, the overall long-term success rate was 41% with 11% demonstrating improvement. Further subgroup analysis of 48 paroxysmal AF patients considered to be optimal candidates for the procedure, revealed a long-term success rate of 69% with an additional 4% demonstrating improvement. A major complication occurred in 7.9% of patients. CONCLUSION: The results reveal that the long-term single-procedure success rate of catheter ablation of AF in a cohort of patients with predominantly non-paroxysmal AF is less than 40%. The inclusion of redo procedures resulted in an improvement in outcomes. A much higher success rate of 69% was achieved in patients with paroxysmal AF considered to be optimal candidates for this procedure. These results make it clear that further advances in the technique of catheter ablation of AF are needed to improve the safety and efficacy of this procedure. In order to be able to compare outcomes of various techniques in differing patient populations, we urge investigators to report long-term single procedure outcomes.

Atrial Fibrillation↗
PubMed2006

Characterization of radiofrequency ablation lesions with gadolinium-enhanced cardiovascular magnetic resonance imaging.

OBJECTIVES: This study was designed to evaluate the characteristics of gadolinium-enhanced imaging of radiofrequency ablations. BACKGROUND: Gadolinium-enhanced magnetic resonance imaging (MRI) has been used successfully to evaluate tissue necrosis after myocardial infarction. In electrophysiology, radiofrequency energy is used to create a targeted myocardial necrosis for the treatment of various arrhythmias. METHODS: Using a power-controlled, cooled-tip 7-F catheter system, radiofrequency lesions (10 to 40 W for 30 s) were created on the epicardium of the right ventricle in eight mongrel dogs. After injection of 0.225 mmol/kg gadolinium, T1-weighted fast gradient echo images were obtained during a follow-up of 10 h using an intrathoracic high-resolution coil. Radiofrequency ablations were analyzed on the MR images and compared with gross anatomy and histopathology. RESULTS: Four distinct phases of signal enhancement were observed. After gadolinium injection, radiofrequency lesions were delineated clearly as contrast-free areas of low signal intensity (contrast-to-noise ratio [CNR] = -21.1 +/- 19.8). Signal enhancement in the lesion periphery started 4.0 +/- 1.8 min after injection and progressively extended toward the lesion center at a rate of 0.02 mm/min. Full delayed enhancement was observed after 98 +/- 21 min (CNR = +17.8 +/- 9.0). During the follow-up period, CNR started to decrease, but the lesions were detectable for as long as 10 h of follow-up. During the first three phases of enhancement, MRI correlated well with the pathological findings (r = 0.88, r = 0.88, and r = 0.86 [p < 0.001], respectively). CONCLUSIONS: Radiofrequency ablation can be evaluated accurately by using gadolinium-enhanced MRI, which may allow the noninvasive assessment of procedural success. The dissimilar wash-in and wash-out kinetics compared with myocardial infarction suggest a different pathophysiological process with complete loss of microvasculature.

Animals↗
PubMed2006

Community lay rescuer automated external defibrillation programs: key state legislative components and implementation strategies: a summary of a decade of experience for healthcare providers, policymakers, legislators, employers, and community leaders from the American Heart Association Emergency Cardiovascular Care Committee, Council on Clinical Cardiology, and Office of State Advocacy.

Cardiovascular disease is a leading cause of death for adults > or =40 years of age. The American Heart Association (AHA) estimates that sudden cardiac arrest is responsible for about 250,000 out-of-hospital deaths annually in the United States. Since the early 1990s, the AHA has called for innovative approaches to reduce time to cardiopulmonary resuscitation (CPR) and defibrillation and improve survival from sudden cardiac arrest. In the mid-1990s, the AHA launched a public health initiative to promote early CPR and early use of automated external defibrillators (AEDs) by trained lay responders in community (lay rescuer) AED programs. Between 1995 and 2000, all 50 states passed laws and regulations concerning lay rescuer AED programs. In addition, the Cardiac Arrest Survival Act (CASA, Public Law 106-505) was passed and signed into federal law in 2000. The variations in state and federal legislation and regulations have complicated efforts to promote lay rescuer AED programs and in some cases have created impediments to such programs. Since 2000, most states have reexamined lay rescuer AED statutes, and many have passed legislation to remove impediments and encourage the development of lay rescuer AED programs. The purpose of this statement is to help policymakers develop new legislation or revise existing legislation to remove barriers to effective community lay rescuer AED programs. Important areas that should be considered in state legislation and regulations are highlighted, and sample legislation sections are included. Potential sources of controversy and the rationale for proposed legislative components are noted. This statement will not address legislation to support home AED programs. Such recommendations may be made after the conclusion of a large study of home AED use.

American Heart Association↗
PubMed2006

Integrated electroanatomic mapping with three-dimensional computed tomographic images for real-time guided ablations.

BACKGROUND: New ablation strategies for atrial fibrillation or nonidiopathic ventricular tachycardia are increasingly based on anatomic consideration and require the placement of ablation lesions at the correct anatomic locations. This study sought to evaluate the accuracy of the first clinically available image integration system for catheter ablation on 3-dimensional (3D) computed tomography (CT) images in real time. METHODS AND RESULTS: After midline sternotomy, 2.3-mm CT fiducial markers were attached to the epicardial surface of each cardiac chamber in 9 mongrel dogs. Detailed 3D cardiac anatomy was reconstructed from contrast-enhanced, high-resolution CT images and registered to the electroanatomic maps of each cardiac chamber. To assess accuracy, targeted ablations were performed at each of the fiducial markers guided only by the reconstructed 3D images. At autopsy, the position error was 1.9+/-0.9 mm for the right atrium, 2.7+/-1.2 mm for the right ventricle, 1.8+/-1.0 mm for the left atrium, and 2.3+/-1.1 mm for the left ventricle. To evaluate the system's guidance of more complex clinical ablation strategies, ablations of the cavotricuspid isthmus (n=4), fossa ovalis (n=4), and pulmonary veins (n=6) were performed, which resulted in position errors of 1.8+/-1.5, 2.2+/-1.3, and 2.1+/-1.2 mm, respectively. Retrospective analysis revealed that a combination of landmark registration and the target chamber surface registration resulted in <3 mm accuracy in all 4 cardiac chambers. CONCLUSIONS: Image integration with high-resolution 3D CT allows accurate placement of anatomically guided ablation lesions and can facilitate complex ablation strategies. This may provide significant advantages for anatomically based procedures such as ablation of atrial fibrillation and nonidiopathic ventricular tachycardia.

Animals↗
PubMed2006

Long-term safety and efficacy of circumferential ablation with pulmonary vein isolation.

BACKGROUND: Each of the two main approaches to catheter ablation of atrial fibrillation (AF, segmental and circumferential) is associated with moderate long-term efficacy. OBJECTIVE: To report the long-term outcomes of a modified technique that combines circumferential ablation with pulmonary vein (PV) isolation, determined by a circular mapping catheter and to determine the relationship between complete PV isolation and long-term efficacy. METHODS: The patient population was composed of 64 consecutive patients (47 men [73%]; age 59 +/- 11 years) with AF who underwent catheter ablation. AF was paroxysmal in 29 (45%) and nonparoxysmal in 35 (55%). Each patient was followed for a minimum of 12 months. RESULTS: After a mean follow-up of 13 +/- 1 months, the long-term single-procedure success rate was 45% (n = 29) with an additional 4% (n = 3) of patients demonstrating improvement. With repeat procedures in 19 patients, the overall long-term success rate was 62% (n = 40) with 9% (n = 6) demonstrating improvement. All the patients who underwent repeat ablations had recovered PV conduction. Incomplete PV isolation was the only independent predictor of failure. A major complication occurred in four (6%) patients, including three patients with vascular complications and one with cardiac tamponade. CONCLUSION: Our results suggest that the long-term single-procedure efficacy of circumferential ablation with PV isolation in a cohort of patients with predominantly nonparoxysmal AF approaches 50%. Repeat procedures involving re-isolation of the PVs result in a significant improvement in outcomes. Complete electrical isolation of the PVs has a significant impact on the long-term efficacy of the procedure.

Atrial Fibrillation↗
PubMed2005

Internal defibrillation with minimal skeletal muscle activation: a new paradigm toward painless defibrillation.

BACKGROUND: Shock-induced pain produces substantial morbidity in recipients of implantable cardioverter-defibrillators (ICDs). This pain likely derives from activation of skeletal muscle and associated nerves in the chest and abdomen. In an effort to develop a painless defibrillation system, we designed an electrode arrangement that incorporates a conductive sock placed around the heart to confine the electric shock field to cardiac tissue. OBJECTIVES: The purpose of this study was to test whether cardiac defibrillation could be achieved without skeletal muscle activation using a novel electrode system. METHODS: Eight adult mongrel dogs were studied. Force of skeletal muscle contraction was measured by strain gauges attached to the forelimbs during delivery of internal shocks ranging in energy from 0.1 to 31 J. Biphasic shocks were delivered (1) between a right ventricular coil and a subcutaneous dummy can (standard configuration), and (2) between a left ventricular coil and an epicardial electrode sock. Internal and external defibrillation thresholds (DFTs) were determined for each electrode configuration. RESULTS: Shock-induced muscle contraction force was significantly lower using the sock electrode than with standard ICD electrodes at every shock energy level tested (P < .0001). Internal DFT was similar between electrode configurations (sock electrode: 8.6 +/- 4.2 J; standard: 11.0 +/- 6.3 J, P = .4), but muscle contraction force at DFT was greatly reduced with the new electrode system (1.8 +/- 2.0 kg vs 10.6 +/- 2.1 kg, P < .0001). The sock electrode rendered external defibrillation impossible, however, even at 360 J. CONCLUSION: Skeletal muscle activation induced by ICD shocks can be greatly reduced using an electrode system that confines the electric shock field to the heart. Refinement of this strategy may allow for delivery of painless shocks by ICDs. Further development is needed to overcome implant complexity and the higher external DFT with this type of electrode system.

Animals↗
PubMed2005

Changes of pulmonary vein orifice size and location throughout the cardiac cycle: dynamic analysis using magnetic resonance cine imaging.

INTRODUCTION: Anatomically guided left atrial ablation is used increasingly for treatment of atrial fibrillation (AF). Three-dimensional mapping systems used for pulmonary veins (PV) encircling ablation procedures anticipate a stable size and position of the PV orifice. The aim of the current study was therefore to analyze changes of PV orifice size and location throughout the cardiac cycle using cine magnetic resonance imaging (MRI). METHODS AND RESULTS: Twenty-five healthy volunteers were studied using a 1.5 Tesla MRI system. MR angiograms were acquired with a breath-hold three-dimensional fast-spoiled gradient-echo imaging (3D FSPGR) sequence in the coronal plane before and after gadolinium injection. Maximum intensity projections and multiplanar reformations were performed to reconstruct images of the PV. Bright blood cine imaging in the axial view was acquired by a steady-state free precession pulse sequence. Twenty bright blood images were obtained per cardiac cycle. The axial (anterior-posterior) PV orifice diameter was measured in all 20 images. For analysis of PV movement the location of the orifice posterior edge was plotted on scale paper. PV orifice size depends on the stage of the cardiac cycle with the largest diameter in late atrial diastole and a mean decrease of 32.5% during atrial systole. Location changes of the PV orifice are in the range of up to 7.2 mm and larger in the coronal (lateral-medial) than in the sagittal (anterior-posterior) direction. CONCLUSION: PV orifice size and location is not as stable as anticipated by three-dimensional mapping systems used for PV encircling left atrial ablation procedures. RF application close to the presumed orifice location should therefore be avoided to minimize the risk of PV stenosis.

Adult↗
PubMed2005

Clinical prediction of cavotricuspid isthmus dependence in patients referred for catheter ablation of "typical" atrial flutter.

INTRODUCTION: Typical atrial flutter (AFL) can be cured by catheter ablation of the cavotricuspid isthmus (CTI). The surface electrocardiogram (ECG) is not always diagnostic of isthmus dependence of AFL. The aim of this study was to evaluate clinical parameters for the prediction of isthmus-dependent AFL. METHODS AND RESULTS: Sixty consecutive adult patients without suspected atriotomy-related AFL, congenital heart disease, or previous AFL ablation, referred for catheter ablation of presumed typical AFL were studied. All patients had distinct flutter waves in the inferior leads, suggestive of CTI-dependent AFL, either on presentation to the electrophysiology (EP) lab or documented on prior ECG. Electrophysiology study was performed in the standard fashion. Patients who presented to the EP laboratory not in AFL underwent arrhythmia induction with a burst pacing protocol. A clinical history of persistent AFL (P = 0.0001) and existence of AFL on presentation to the EP laboratory (P = 0.0001) were strong predictors of CTI dependence. History of atrial fibrillation (P = 0.19), structural heart disease (P = 0.6), hypertension (P = 0.4), and previous cardiac surgery (P = 0.5), as well as the nature of AFL-related symptoms (P = 0.5), were not predictors of CTI-dependent AFL documented during EP study. CONCLUSION: In patients with ECG suggestive of typical AFL, the presence of persistent rather than paroxysmal AFL and presentation to the EP laboratory in AFL are strong predictors of CTI-dependent AFL. A paroxysmal pattern of AFL predicts noninducibility of CTI-dependent AFL during EP study. CTI ablation may therefore be less effective in these patients.

Atrial Flutter↗
PubMed2004

Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries: a statement for healthcare professionals from a task force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Councils of Southern Africa).

Outcome after cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002, a task force of the International Liaison Committee on Resuscitation (ILCOR) met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (ie, essential and desirable) data elements recommended by previous Utstein consensus conferences. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, emergency medical services system, and community.

Adult↗
PubMed2004

Improved hemodynamic performance with a novel chest compression device during treatment of in-hospital cardiac arrest.

INTRODUCTION: The purpose of this pilot clinical study was to determine if a novel chest compression device would improve hemodynamics when compared to manual chest compression during cardiopulmonary resuscitation (CPR) in humans. The device is an automated self-adjusting electromechanical chest compressor based on AutoPulse technology (Revivant Corporation) that uses a load distributing compression band (A-CPR) to compress the anterior chest. METHODS: A total of 31 sequential subjects with in-hospital sudden cardiac arrest were screened with institutional review board approval. All subjects had received prior treatment for cardiac disease and most had co-morbidities. Subjects were included following 10 min of failed standard advanced life support (ALS) protocol. Fluid-filled catheters were advanced into the thoracic aorta and the right atrium and placement was confirmed by pressure waveforms and chest radiograph. The coronary perfusion pressure (CPP) was measured as the difference between the aortic and right atrial pressure during the chest compression's decompressed state. Following 10 min of failed ALS and catheter placement, subjects received alternating manual and A-CPR chest compressions for 90 s each. Chest compressions were administered without ventilation pauses at 100 compressions/min for manual CPR and 60 compressions/min for A-CPR. All subjects were intubated and ventilated by bag-valve at 12 breaths/min between compressions. Epinephrine (adrenaline) (1mg i.v. bolus) was given at the request of the attending physician at 3-5 min intervals. Usable pressure signals were present in 16 patients (68 +/- 6 years, 5 female), and data are reported from those patients only. A-CPR chest compressions increased peak aortic pressure when compared to manual chest compression (153 +/- 28 mmHg versus 115 +/- 42 mmHg, P < 0.0001, mean +/- S.D.). Similarly, A-CPR increased peak right atrial pressure when compared to manual chest compression (129 +/- 32 mmHg versus 83 +/- 40 mmHg, P < 0.0001). Furthermore, A-CPR increased CPP over manual chest compression (20 +/- 12 mmHg versus 15 +/- 11 mmHg, P < 0.015). Manual chest compressions were of consistent high quality (51 +/- 20 kg) and in all cases met or exceeded American Heart Association guidelines for depth of compression. CONCLUSION: Previous research has shown that increased CPP is correlated to increased coronary blood flow and increased rates of restored native circulation from sudden cardiac arrest. The A-CPR system using AutoPulse technology demonstrated increased coronary perfusion pressure over manual chest compression during CPR in this terminally ill patient population.

Aged↗
PubMed2004

Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries. A statement for healthcare professionals from a task force of the international liaison committee on resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Southern Africa).

Outcome following cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002 a task force of ILCOR met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (i.e., essential and desirable) data elements recommended by previous Utstein consensus conference. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, EMS system, and community.

Adult↗
PubMed2004

Stereotactic magnetic resonance guidance for anatomically targeted ablations of the fossa ovalis and the left atrium.

INTRODUCTION: Targets for radiofrequency ablation (RFA) of atrial fibrillation are increasingly being selected based on anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures, we evaluated whether stereotactic catheter guidance might facilitate anatomical catheter navigation and RFA to the great vessels, the fossa ovalis and the left atrium (LA). METHODS AND RESULTS: An electromagnetic catheter's position system was superimposed on three-dimensional (3D) MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MRI in real-time. To assess the reproducibility of RFA, repeat ablations were created at the identical anatomic site in the inferior vena cava (IVC) in 5 swine. Average distance of the repeated ablations was 4.4 +/- 2.4 mm.In five swine the catheter was anatomically guided with the MRI to the fossa ovalis and a single RFA was performed. On the pathological specimen all ablation sites were located within the fossa ovalis with an average distance of 3.9 +/- 2.1 mm from its center. In two of the experiments the ablation catheter was passed into the left atrium and anatomically targeted ablation performed in the lateral wall of the left atrial appendage. Catheter location and ablation site were confirmed by autopsy and histology. CONCLUSION: Real-time display of the catheter position on 3D-MRI allows anatomically targeted catheter navigation and RFA in the IVC, the fossa ovalis, and the left atrium. This may facilitate anatomically based interventions like septal puncture or pulmonary vein ablation and decrease fluoroscopy times.

Animals↗
PubMed2004

Characterization of a new pulmonary vein variant using magnetic resonance angiography: incidence, imaging, and interventional implications of the "right top pulmonary vein".

INTRODUCTION: Catheter ablation of the pulmonary veins (PVs) for prevention of recurrent atrial fibrillation requires precise anatomic information. We describe the characteristics of a new anatomic variant of PV anatomy using magnetic resonance angiography. METHODS AND RESULTS: A 1.5-T magnetic resonance imaging system with a body coil or a torso phased-array coil was used before and after gadolinium injection. Magnetic resonance angiograms were acquired with a breath-hold three-dimensional fast spoiled gradient-echo imaging sequence in the coronal plane. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. A newly described variant PV ascending from the roof of the left atrium was found in 3 of 91 subjects. The mean ostial diameter of the roof PV was 7 +/- 2 mm, the mean distance from the ostium to the first branching point was 22 +/- 8.5 mm, and the mean distance to the right superior PV was 3.3 +/- 0.6 mm. CONCLUSION: We refer to the newly described variant of PV anatomy as the "right top pulmonary vein." It is important to be aware of this anatomic pattern to avoid inadvertent catheter intubation, which can result in misleading mapping results and PV stenosis.

Adult↗
PubMed2003

Anatomic stereotactic catheter ablation on three-dimensional magnetic resonance images in real time.

BACKGROUND: Targets for radiofrequency (RF) ablation of atrial fibrillation, atrial flutter, and nonidiopathic ventricular tachycardia are increasingly being selected on the basis of anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures and is associated with radiation risk, other approaches to mapping may be beneficial. METHODS AND RESULTS: An electromagnetic catheter positioning system was superimposed on 3D MR images using fiducial markers. This allowed the dynamic display of the catheter position on the true anatomy of previously acquired MR images in real time. In vitro accuracy and precision during catheter navigation were assessed in a phantom model and were 1.11+/-0.06 and 0.30+/-0.07 mm (mean+/-SEM), respectively. Left and right heart catheterization was performed in 7 swine without the use of fluoroscopy, yielding an in vivo accuracy and precision of 2.74+/-0.52 and 1.97+/-0.44 mm, respectively. To assess the reproducibility of RF ablation, RF lesions were created repeatedly at the identical anatomic site in the right atrium (n=8 swine). Average distance of the repeated right atrial ablations was 3.92+/-0.5 mm. Straight 3-point lines were created in the right and left ventricles to determine the ability to facilitate complex ablation procedures (n=6 swine). The ventricular lesions deviated 1.70+/-0.24 mm from a straight line, and the point distance differed by 2.25+/-0.63 mm from the pathological specimen. CONCLUSIONS: Real-time display of the catheter position on 3D MRI allows accurate and precise RF ablation guided by the true anatomy. This may facilitate anatomically based ablation procedures in, for instance, atrial fibrillation or nonidiopathic ventricular tachycardia and decrease radiation times.

Animals↗
PubMed2003

Initial experience with a novel focused ultrasound ablation system for ring ablation outside the pulmonary vein.

INTRODUCTION: Atrial fibrillation has been shown to initiate from triggers within pulmonary veins. Several studies have documented that electrical isolation of those triggers can lead to maintenance of sinus rhythm. The complication of pulmonary vein stenosis has limited the utility of delivering ablation energy within the pulmonary vein. We utilize a focused ultrasound catheter ablation system for delivery of transmural ablation lines proximal to the pulmonary vein ostium. METHODS: Nine dogs (weight 30-39 kg) were anesthetized and ventilated. Through a transseptal approach, pulmonary veins were engaged with the focused balloon ultrasound catheter. Ultrasound power was delivered at 40 acoustic watts outside the pulmonary vein ostium, focused 2 mm off the balloon surface, with a depth of approximately 6 mm, for 30-120 seconds. Following ablation, lesions were histopathologically analyzed. RESULTS: Of nine animals studied, fourteen pulmonary veins were ablated. We found successful delivery of near circumferential and transmural ablation lines in 6/14 pulmonary veins. In each of the six circumferential ablations, successful alignment of the ultrasound transducer along the longitudinal axis of the parabolic balloon occurred. The final four ablations were conducted with an enhanced catheter design that assured axial alignment. Of these ablations, all four were circumferential. The remaining 8 pulmonary veins had incomplete delivery of lesions. In each of these veins the ultrasound transducer was misaligned with the balloon axis when therapy was delivered. CONCLUSION: Focused ultrasound ablation is a new means of performing pulmonary vein isolation. This method provides delivery of lesions outside the vein, limiting the risk of pulmonary vein stenosis for the treatment of atrial fibrillation.

Animals↗
PubMed2002

Systolic improvement and mechanical resynchronization does not require electrical synchrony in the dilated failing heart with left bundle-branch block.

BACKGROUND: Biventricular (BiV) and left ventricular (LV) pacing similarly augment systolic function in left bundle-branch block (LBBB)-failing hearts despite different electrical activation. We tested whether electrical synchrony is required to achieve mechanical synchronization and functional benefit from pacing. METHODS AND RESULTS: Epicardial mapping, tagged MRI, and hemodynamics were obtained in dogs with LBBB-failing hearts during right atrial, LV, and BiV stimulation. BiV and LV both significantly improved chamber hemodynamics (eg, 25% increase in dP/dt(max) and aortic pulse pressure) compared with atrial pacing-LBBB, and this improvement correlated with mechanical resynchronization. Electrical dispersion, however, decreased 13% with BiV but increased 23% with LV pacing (P<0.01). CONCLUSION: Improved mechanical synchrony and function do not require electrical synchrony. Mechanical coordination plays the dominant role in global systolic improvement with either pacing approach.

Animals↗