Allan C Skanes

Western University, London, Ontario, Canada

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Publications (324)1467.99 Total impact

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    ABSTRACT: Goal: Maintaining a constant contact force of an ablation catheter during cardiac catheter ablation therapy is clinically challenging due to inherent myocardial motion, often resulting in poor ablation of arrhythmogenic substrates. To enable a prescribed contact force to be applied during ablation, a catheter contact force controller (CCFC) was developed. Methods: The system includes a hand-held device attached to a commercial catheter and steerable sheath. A compact linear motor assembly attaches to an ablation catheter and autonomously controls its relative position within the shaft of the steerable sheath. A closed-loop control system is implemented within embedded electronics to enable real-time catheter-tissue contact force control. To evaluate the performance of the CCFC, a linear motion phantom was used to impose a series of physiological contact force profiles; lesion contact force was controlled at prescribed levels ranging from 15 to 40 g. Results: For a prescribed contact force of 25 g, the CCFC was able to regulate the contact force with a root mean squared error of 3.7 ± 0.7 g. The ability of the CCFC to retract the catheter upon sudden changes in tissue motion, which may have caused tissue damage, was also demonstrated. Finally, the device was able to regulate the contact force for a predetermined amount of time according to a force-time integral model. Conclusion: The developed CCFC is capable of regulating catheter-tissue contact force in a laboratory setting that mimics clinical ablation therapy. Significance: Catheter-tissue contact force control promises to improve the precision and success of ablation lesion delivery.
    No preview · Article · Feb 2016 · IEEE Transactions on Biomedical Engineering
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    ABSTRACT: Brief episodes of physical exertion are associated with an immediately higher risk of cardiovascular events. Prior studies on the risk of ventricular arrhythmia (VA) shortly after exertion have not assessed if this risk differs by level of aerobic fitness or sedentary behaviour. Therefore, we conducted a prospective cohort study of patients with implantable cardioverter-defibrillators (ICD) with a nested case-crossover analysis to examine the risk of VA shortly after exertion and whether this risk is modified by aerobic fitness and sedentary behaviour.
    No preview · Article · Dec 2015 · The Canadian journal of cardiology
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    ABSTRACT: Background: A full circumferential set of antral lesions is not always required for bidirectional pulmonary vein conduction block. It is unknown whether a partial lesion set that isolates the veins will have clinical success rates similar to a full circumferential lesion set, and if procedural times or procedural risk will be affected. Methods: We performed a prospective, randomized clinical trial to test the hypothesis that a partial lesion set that isolates the pulmonary veins has comparable clinical success rate and shorter procedure times compared to a strategy of completing the circumferential lesion set once the veins are isolated. Results: 119 patients were enrolled, 59 randomized to circumferential ablation and 60 to segmental. Mean age was 58.3 +/- 10.1, 77% male. Mean procedure time was 221.0±46.9 minutes in circumferential and 224.7±51.3 in segmental (p = 0.68). 12-month freedom from AF recurrence was 61.3% overall, 64.4% in circumferential and 58.3% in segmental (p = 0.50). Among 25 segmental patients with AF recurrence, 23 underwent second ablation. Among 33 areas of conduction recovery, 23 (70%) occurred in segments ablated at first procedure and 10 (30%) in segments not previously ablated, suggesting reversible conduction block from edema. Conclusion: No difference in AF recurrence or procedure time is detectable in a sample of 119 patients randomized to segmental or circumferential antral ablation to achieve pulmonary vein isolation. Second ablation procedures confirmed that some antral sites do not require ablation. A segmental approach results in unacceptably high rates of untargeted or recovered antral sites to make this approach feasible. This article is protected by copyright. All rights reserved.
    No preview · Article · Nov 2015 · Journal of Cardiovascular Electrophysiology
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    ABSTRACT: Background: Remote catheter navigation systems protect interventionalists from scattered ionizing radiation. However, these systems typically require specialized catheters and extensive operator training. Methods: A new compact and sterilizable telerobotic system is described, which allows remote navigation of conventional tip-steerable catheters, with three degrees of freedom, using an interface that takes advantage of the interventionalist's existing dexterity skills. The performance of the system is evaluated ex vivo and in vivo for remote catheter navigation and ablation delivery. Results: The system has absolute errors of 0.1 ± 0.1 mm and 7 ± 6° over 100 mm of axial motion and 360° of catheter rotation, respectively. In vivo experiments proved the safety of the proposed telerobotic system and demonstrated the feasibility of remote navigation and delivery of ablation. Conclusion: The proposed telerobotic system allows the interventionalist to use conventional steerable catheters; while maintaining a safe distance from the radiation source, he/she can remotely navigate the catheter and deliver ablation lesions. Copyright © 2015 John Wiley & Sons, Ltd.
    No preview · Article · Nov 2015 · International Journal of Medical Robotics and Computer Assisted Surgery
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    ABSTRACT: Background: Real-world data on patients' and physicians' values related to the use of oral anticoagulant (OAC) therapy for stroke prevention in patients with nonvalvular atrial fibrillation are currently lacking. We sought to assess the values, preferences, and experience of patients who receive OAC therapy, and of physicians who prescribe OAC therapy. Methods: A national survey of randomly selected patients (n = 266) and physicians (n = 178) was conducted between May and September 2014. Each was asked to evaluate the importance of individual OAC attributes and identify which of 2 medication profiles they would prefer (individual attributes were progressively modified to determine which were the most valued and/or influenced treatment choice). Medication adherence and prescription practice was also assessed. Results: The preferences of patients and physicians regarding OAC therapy differed but largely focused on characteristics related to safety and, to a lesser extent, efficacy. When based solely on the basis of the attribute profile (blinded to the specific agent), physicians were more likely to select apixaban (61%), whereas patients showed no significant preference among apixaban, rivaroxaban, and warfarin. Despite this, 49% of physicians spontaneously stated rivaroxaban as their preferred agent (vs 25% apixaban). Patients prescribed and taking once daily medications (rivaroxaban or warfarin) showed better compliance with their OAC therapy (approximately 30% of twice daily medications being taken once daily, with significantly more missed doses compared with once daily medications). Conclusions: Real-world prescriptions do not reflect reported values, which suggests that other factors influence patient-physician decision-making around OAC therapy. Data on self-reported adherence to OAC therapy and discordance in the use of OACs from prescribed regimens are concerning and warrant further investigation.
    No preview · Article · Nov 2015 · The Canadian journal of cardiology
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    ABSTRACT: A 62-year-old retired police officer was referred to our institution for an episode of sustained monomorphic wide complex tachycardia requiring defibrillation at a peripheral hospital. He had a history of hypertension and hyperlipidemia and his only medication at presentation was atorvastatin. The morning of his presentation he felt fatigued and light-headed. He presented to the emergency room and his resting electrocardiogram (ECG) revealed a wide complex tachycardia (WCT) at 190 bpm with a left bundle branch block pattern. He was cardioverted with 200 J and admitted to hospital. His post-cardioversion ECG revealed sinus rhythm with subtle inferolateral ST depression and T-wave inversion. This article is protected by copyright. All rights reserved.
    No preview · Article · Oct 2015 · Journal of Cardiovascular Electrophysiology

  • No preview · Article · Oct 2015 · The Canadian journal of cardiology

  • No preview · Article · Oct 2015 · The Canadian journal of cardiology
  • Allan C Skanes · Manoj Obeyesekere · George J Klein
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    ABSTRACT: The association between asymptomatic Wolff-Parkinson-White (WPW) syndrome and sudden cardiac death (SCD) has been well documented. The inherent properties of the accessory pathway determine the risk of SCD in WPW, and catheter ablation essentially eliminates this risk. An approach to WPW syndrome is needed that incorporates the patient's individualized considerations into the decision making. Patients must understand that there is a trade-off of a small immediate risk of an invasive approach for elimination of a small lifetime risk of the natural history of asymptomatic WPW. Clinicians can minimize the invasive risk by only performing ablation for patients with at-risk pathways. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Sep 2015 · Cardiac electrophysiology clinics
  • Umjeet S Jolly · Kevin K Ng · Allan C Skanes

    No preview · Article · May 2015 · Heart rhythm: the official journal of the Heart Rhythm Society
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    ABSTRACT: Corrected QT (QTc) interval prolongation has been shown to be an independent predictor of mortality in many clinical settings and is a common finding in hospitalized patients. The causes and outcomes of patients with extreme QTc interval prolongation during a hospital admission are poorly described. The aim of this study was to prospectively identify patients with automated readings of QTc intervals >550 ms at 1 academic tertiary hospital. One hundred seventy-two patients with dramatic QTc interval prolongation (574 ± 53 ms) were identified (mean age 67.6 ± 15.1 years, 48% women). Most patients had underlying heart disease (60%), predominantly ischemic cardiomyopathy (43%). At lease 1 credible and presumed reversible cause associated with QTc interval prolongation was identified in 98% of patients. The most common culprits were QTc interval-prolonging medications, which were deemed most responsible in 48% of patients, with 25% of these patients taking ≥2 offending drugs. Two patients were diagnosed with congenital long-QT syndrome. Patients with electrocardiograms available before and after hospital admission demonstrated significantly lower preadmission and postdischarge QTc intervals compared with the QTc intervals recorded in the hospital. In conclusion, in-hospital mortality was high in the study population (29%), with only 4% of patients experiencing arrhythmic deaths, all of which were attributed to secondary causes. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Jan 2015 · The American Journal of Cardiology
  • Mahta Khoshnam Tehrani · Allan C. Skanes · Rajni V. Patel
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    ABSTRACT: The efficacy of catheter-based cardiac ablation procedures can be significantly improved if real-time information is available concerning contact forces between the catheter-tip and cardiac tissue. However, the widely used ablation catheters are not equipped for force sensing. This paper proposes a technique for estimating the contact forces without direct force measurements by studying the changes in the shape of the deflectable distal section of a conventional 7-Fr catheter (henceforth called the "deflectable distal shaft", the "deflectable shaft" or the "shaft" of the catheter) in different loading situations. Method: First, the shaft curvature when the tip is moving in free space is studied and based on that, a kinematic model for the deflectable shaft in free space is proposed. In the next step, the shaft shape is analyzed in the case where the tip is in contact with the environment, and it is shown that the curvature of the deflectable shaft provides useful information about the loading status of the catheter and can be used to define an index for determining the range of contact forces exerted by the ablation tip. Results: Experiments with two different steerable ablation catheters show that the defined index can detect the range of applied contact forces correctly in more than 80% of the cases. Based on the proposed technique, a framework for obtaining contact force information by using the shaft curvature at a limited number of points along the deflectable shaft is constructed. Conclusion: The proposed kinematic model and the force estimation technique can be implemented together to describe the catheter's behavior before contact, detect tip/tissue contact and determine the range of contact forces. Significance: This study proves that the flexibility of the catheter's distal shaft provides a means of estimating the force exerted on tissue by the ablation tip.
    No preview · Article · Jan 2015 · IEEE transactions on bio-medical engineering
  • Andrew D. Krahn · Raymond Yee · Allan C. Skanes · George J. Klein

    No preview · Chapter · Dec 2014
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    ABSTRACT: The objectives of this national chart audit (January to June 2013) of 6,346 patients with atrial fibrillation (AF; ≥18 years without a significant heart valve disorder) from 647 primary care physicians were to (1) describe the frequency of stroke and bleed risk assessments in patients with nonvalvular AF by primary care physicians, including the accuracy of these assessments relative to established predictive indexes; (2) outline contemporary methods of anticoagulation used; and (3) report the time in the therapeutic range among patients prescribed warfarin. An annual stroke risk assessment was not undertaken in 15% and estimated without a formal risk tool in 33%; agreement with CHADS2 score estimation was seen in 87% of patients. Major bleeding risk assessment was not undertaken in 25% and estimated without a formal risk tool in 47%; agreement with HAS-BLED score estimation was observed in 64% with physician overestimation in 26% of patients. Antithrombotic therapy included warfarin (58%), dabigatran (22%), rivaroxaban (14%), and apixaban (<1%). Among warfarin-treated patients, the median international normalized ratio was 2.4 and time in therapeutic range (TTR) was 73%; however, the TTR was <50% in 845 (25%), 50% to 69% in 674 (20%), and ≥70% in 1,827 (55%) patients. In conclusion, we describe a contemporary real-world elderly population with AF at important risk for stroke. There is apparent overestimation of bleeding risk in many patients. Warfarin was the dominant stroke prevention treatment; however, the suggested TTR target was achieved in only 55% of these patients. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Dec 2014 · The American Journal of Cardiology
  • Lorne J Gula · Allan C Skanes
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    ABSTRACT: Pulmonary vein isolation (PVI) has rapidly become a common procedure for management of atrial fibrillation (AF). With a success rate higher than antiarrhythmic medication and a relatively low risk, ablation is now a reasonable consideration for most patients with AF. The main argument against routine use of ablation as first line therapy for AF is the rare but real risk of life-threatening complications. Among the most concerning of the potential late complications is atrial-esophageal fistula. This complication is difficult to study given its fortunately low incidence, with 5 fistulae reported among 45,115 procedures in a study of 546 worldwide centers(1) . But with a mortality rate close to 100% - a recent report(2) detailed deaths in all 5 patients within a week of esophageal stenting, in contrast to 2+ year survival in all 4 patients undergoing surgery within 4 hours of diagnosis - it has remained a high priority to attempt to study, understand, and prevent this devastating complication. As with any condition that is too rare to study directly, many investigators have looked to a surrogate outcome, in this case mucosal erosions and ulceration detected by esophageal imaging after ablation. We have been tempted to consider such ulcers as minor forms of potential fistulas, and therefore investigate these lesions with the belief that we are learning more about the full blown condition. But it seems we may need to learn more about the ulcers themselves, specifically, whether a subset of these lesions are in fact due to mechanical trauma from a TEE probe and unrelated to ablation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · Dec 2014 · Journal of Cardiovascular Electrophysiology
  • Kevin K. Ng · Allan C. Skanes

    No preview · Article · Nov 2014 · The Canadian journal of cardiology
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    ABSTRACT: The acceptance and yield of family screening in genotype-negative long QT syndrome (LQTS) remains incompletely characterized. In this study of family screening for phenotype-definite Long QT Syndrome (LQTS, Schwartz score ≥3.5), probands at a regional Inherited Cardiac Arrhythmia clinic were reviewed. All LQTS patients were offered education by a qualified genetic counselor, along with materials for family screening including electronic and paper correspondence to provide to family members. Thirty-eight qualifying probands were identified and 20 of these had family members who participated in cascade screening. The acceptance of screening was found to be lower among families without a known pathogenic mutation (33 vs. 77 %, p = 0.02). A total of 52 relatives were screened; fewer relatives were screened per index case when the proband was genotype-negative (1.7 vs. 3.1, p = 0.02). The clinical yield of screening appeared to be similar irrespective of gene testing results (38 vs. 33 %, p = 0.69). Additional efforts to promote family screening among gene-negative long QT families may be warranted.
    No preview · Article · Oct 2014 · Journal of Genetic Counseling

  • No preview · Article · Oct 2014 · The Canadian journal of cardiology

  • No preview · Article · Oct 2014 · The Canadian journal of cardiology
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    ABSTRACT: Background: Left ventricular (LV) and right ventricular pacing site characteristics have been shown to influence response to cardiac resynchronization therapy (CRT). This study aimed to determine the clinical feasibility of image-guided lead delivery using a 3-dimensional navigational model displaying both LV and right ventricular (RV) pacing targets. Serial echocardiographic measures of clinical response and procedural metrics were evaluated. Methods and results: Thirty-one consecutive patients underwent preimplant cardiac MRI with the generation of a 3-dimensional navigational model depicting optimal segmental targets for LV and RV leads. Lead delivery was guided by the model in matched views to intraprocedural fluoroscopy. Blinded assessment of final lead tip location was performed from postprocedural cardiac computed tomography. Clinical and LV remodeling response criteria were assessed at baseline, 3 months, and 6 months using a 6-minute hall walk, quality of life questionnaire, and echocardiography. Mean age and LV ejection fraction was 66 ± 8 years and 26 ± 8%, respectively. LV leads were successfully delivered to a target or adjacent segment in 30 of 31 patients (97%), 68% being nonposterolateral. RV leads were delivered to a target or adjacent segment in 30 of 31 patients (97%), 26% being nonapical. Twenty-three patients (74%) met standard criteria for response (LV end-systolic volume reduction ≥ 15%), 18 patients (58%) for super-response (LV end-systolic volume reduction ≥ 30%). LV ejection fraction improved at 6 months (31 ± 8 versus 26 ± 8%, P=0.04). Conclusions: This study demonstrates clinical feasibility of dual cardiac resynchronization therapy lead delivery to optimal targets using a 3-dimensional navigational model. High procedural success, acceptable procedural times, and a low rate of early procedural complications were observed. Clinical trial registration url: Unique identifier: NCT01640769.
    Full-text · Article · Sep 2014 · Circulation Arrhythmia and Electrophysiology

Publication Stats

9k Citations
1,467.99 Total Impact Points


  • 2012-2015
    • Western University
      London, Ontario, Canada
  • 2000-2015
    • The University of Western Ontario
      • • Division of Cardiology
      • • Department of Medicine
      London, Ontario, Canada
    • Syracuse University
      Syracuse, New York, United States
  • 2000-2014
    • London Health Sciences Centre
      • Division of Cardiology
      London, Ontario, Canada
  • 2011
    • CHU de Québec
      Quebec City, Quebec, Canada
    • Robarts Research Institute
      • Imaging Research Laboratories
      London, Ontario, Canada
  • 2005
    • Lawson Health Research Institute
      London, Ontario, Canada
  • 1997-2005
    • University of Ottawa
      • Department of Medicine
      Ottawa, Ontario, Canada
    • Ottawa University
      اوتاوا، کانزاس, Kansas, United States