Contact force and ablation assessment of surgical bipolar radiofrequency clamps in the treatment of atrial fibrillation

Jason A. Varzaly, Darius Chapman, Dennis H. Lau, Suzanne Edwards, Jennie Louise, James Edwards, Rajiv Mahajan, Michael Worthington, Prash Sanders

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

OBJECTIVES: Atrial fibrillation is treated surgically by creating conduction block lesions. Radiofrequency (RF) lesions have reduced efficacy compared to 'cut-and-sew'. Catheter ablation studies demonstrate a relationship between lesion depth and contact force. We hypothesized that contact force and lesion depth are dependent on design of the bipolar surgical RF clamps. METHODS: Hinged and parallel jaw style RF clamps were studied. Muscle samples were clamped with pressure-sensitive film at increasing tissue thicknesses. Films were analysed determining clamp pressure profiles. A sheep model was utilized for ablation testing using each clamp style until the device indicated transmurality. Separate muscle areas had 1, 2 or 3 burns applied. The muscle was excised, sectioned every 1 cm and stained for lesion depth and fat thickness analysis. RESULTS: Pressure profiling comparing the proximal and distal segments of each clamp style demonstrated only one statistically significant difference in the parallel clamp; the hinged clamp had statistically significant differences (P <0.03) for all tissue thicknesses. There was no evidence for differences in the proximal lesion depth of both clamps (P = 0.13) but deeper distally in the parallel clamp (10.17mm vs 8.02 mm, P = 0.003). The logistic regression analysis demonstrated increased odds of transmurality with parallel clamps at 1, 2 or 3 burns (P = 0.03, P = 0.003 and P = 0.002). Every 1mm increase in overlying fat decreased likelihood of transmurality by 11% (P < 0.05). CONCLUSIONS: The parallel and hinged clamps have different pressure profiles with higher likelihood of transmurality using the parallel clamp. Fat reduces the ability of RF to deliver a transmural lesion. These findings have implications for optimal surgical RF ablation technique.

LanguageEnglish
Pages85-93
Number of pages9
JournalInteractive Cardiovascular and Thoracic Surgery
Volume28
Issue number1
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • Ablation
  • Atrial fibrillation
  • Contact force
  • Lesion
  • Radiofrequency
  • Surgery

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine

Cite this

Varzaly, Jason A. ; Chapman, Darius ; Lau, Dennis H. ; Edwards, Suzanne ; Louise, Jennie ; Edwards, James ; Mahajan, Rajiv ; Worthington, Michael ; Sanders, Prash. / Contact force and ablation assessment of surgical bipolar radiofrequency clamps in the treatment of atrial fibrillation. In: Interactive Cardiovascular and Thoracic Surgery. 2019 ; Vol. 28, No. 1. pp. 85-93.
@article{939bdb6ed87d48a5a52bb26c1c844a99,
title = "Contact force and ablation assessment of surgical bipolar radiofrequency clamps in the treatment of atrial fibrillation",
abstract = "OBJECTIVES: Atrial fibrillation is treated surgically by creating conduction block lesions. Radiofrequency (RF) lesions have reduced efficacy compared to 'cut-and-sew'. Catheter ablation studies demonstrate a relationship between lesion depth and contact force. We hypothesized that contact force and lesion depth are dependent on design of the bipolar surgical RF clamps. METHODS: Hinged and parallel jaw style RF clamps were studied. Muscle samples were clamped with pressure-sensitive film at increasing tissue thicknesses. Films were analysed determining clamp pressure profiles. A sheep model was utilized for ablation testing using each clamp style until the device indicated transmurality. Separate muscle areas had 1, 2 or 3 burns applied. The muscle was excised, sectioned every 1 cm and stained for lesion depth and fat thickness analysis. RESULTS: Pressure profiling comparing the proximal and distal segments of each clamp style demonstrated only one statistically significant difference in the parallel clamp; the hinged clamp had statistically significant differences (P <0.03) for all tissue thicknesses. There was no evidence for differences in the proximal lesion depth of both clamps (P = 0.13) but deeper distally in the parallel clamp (10.17mm vs 8.02 mm, P = 0.003). The logistic regression analysis demonstrated increased odds of transmurality with parallel clamps at 1, 2 or 3 burns (P = 0.03, P = 0.003 and P = 0.002). Every 1mm increase in overlying fat decreased likelihood of transmurality by 11{\%} (P < 0.05). CONCLUSIONS: The parallel and hinged clamps have different pressure profiles with higher likelihood of transmurality using the parallel clamp. Fat reduces the ability of RF to deliver a transmural lesion. These findings have implications for optimal surgical RF ablation technique.",
keywords = "Ablation, Atrial fibrillation, Contact force, Lesion, Radiofrequency, Surgery",
author = "Varzaly, {Jason A.} and Darius Chapman and Lau, {Dennis H.} and Suzanne Edwards and Jennie Louise and James Edwards and Rajiv Mahajan and Michael Worthington and Prash Sanders",
year = "2019",
month = "1",
day = "1",
doi = "10.1093/icvts/ivy191",
language = "English",
volume = "28",
pages = "85--93",
journal = "Interactive cardiovascular and thoracic surgery",
issn = "1569-9293",
publisher = "Oxford University Press",
number = "1",

}

Varzaly, JA, Chapman, D, Lau, DH, Edwards, S, Louise, J, Edwards, J, Mahajan, R, Worthington, M & Sanders, P 2019, 'Contact force and ablation assessment of surgical bipolar radiofrequency clamps in the treatment of atrial fibrillation', Interactive Cardiovascular and Thoracic Surgery, vol. 28, no. 1, pp. 85-93. https://doi.org/10.1093/icvts/ivy191

Contact force and ablation assessment of surgical bipolar radiofrequency clamps in the treatment of atrial fibrillation. / Varzaly, Jason A.; Chapman, Darius; Lau, Dennis H.; Edwards, Suzanne; Louise, Jennie; Edwards, James; Mahajan, Rajiv; Worthington, Michael; Sanders, Prash.

In: Interactive Cardiovascular and Thoracic Surgery, Vol. 28, No. 1, 01.01.2019, p. 85-93.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Contact force and ablation assessment of surgical bipolar radiofrequency clamps in the treatment of atrial fibrillation

AU - Varzaly, Jason A.

AU - Chapman, Darius

AU - Lau, Dennis H.

AU - Edwards, Suzanne

AU - Louise, Jennie

AU - Edwards, James

AU - Mahajan, Rajiv

AU - Worthington, Michael

AU - Sanders, Prash

PY - 2019/1/1

Y1 - 2019/1/1

N2 - OBJECTIVES: Atrial fibrillation is treated surgically by creating conduction block lesions. Radiofrequency (RF) lesions have reduced efficacy compared to 'cut-and-sew'. Catheter ablation studies demonstrate a relationship between lesion depth and contact force. We hypothesized that contact force and lesion depth are dependent on design of the bipolar surgical RF clamps. METHODS: Hinged and parallel jaw style RF clamps were studied. Muscle samples were clamped with pressure-sensitive film at increasing tissue thicknesses. Films were analysed determining clamp pressure profiles. A sheep model was utilized for ablation testing using each clamp style until the device indicated transmurality. Separate muscle areas had 1, 2 or 3 burns applied. The muscle was excised, sectioned every 1 cm and stained for lesion depth and fat thickness analysis. RESULTS: Pressure profiling comparing the proximal and distal segments of each clamp style demonstrated only one statistically significant difference in the parallel clamp; the hinged clamp had statistically significant differences (P <0.03) for all tissue thicknesses. There was no evidence for differences in the proximal lesion depth of both clamps (P = 0.13) but deeper distally in the parallel clamp (10.17mm vs 8.02 mm, P = 0.003). The logistic regression analysis demonstrated increased odds of transmurality with parallel clamps at 1, 2 or 3 burns (P = 0.03, P = 0.003 and P = 0.002). Every 1mm increase in overlying fat decreased likelihood of transmurality by 11% (P < 0.05). CONCLUSIONS: The parallel and hinged clamps have different pressure profiles with higher likelihood of transmurality using the parallel clamp. Fat reduces the ability of RF to deliver a transmural lesion. These findings have implications for optimal surgical RF ablation technique.

AB - OBJECTIVES: Atrial fibrillation is treated surgically by creating conduction block lesions. Radiofrequency (RF) lesions have reduced efficacy compared to 'cut-and-sew'. Catheter ablation studies demonstrate a relationship between lesion depth and contact force. We hypothesized that contact force and lesion depth are dependent on design of the bipolar surgical RF clamps. METHODS: Hinged and parallel jaw style RF clamps were studied. Muscle samples were clamped with pressure-sensitive film at increasing tissue thicknesses. Films were analysed determining clamp pressure profiles. A sheep model was utilized for ablation testing using each clamp style until the device indicated transmurality. Separate muscle areas had 1, 2 or 3 burns applied. The muscle was excised, sectioned every 1 cm and stained for lesion depth and fat thickness analysis. RESULTS: Pressure profiling comparing the proximal and distal segments of each clamp style demonstrated only one statistically significant difference in the parallel clamp; the hinged clamp had statistically significant differences (P <0.03) for all tissue thicknesses. There was no evidence for differences in the proximal lesion depth of both clamps (P = 0.13) but deeper distally in the parallel clamp (10.17mm vs 8.02 mm, P = 0.003). The logistic regression analysis demonstrated increased odds of transmurality with parallel clamps at 1, 2 or 3 burns (P = 0.03, P = 0.003 and P = 0.002). Every 1mm increase in overlying fat decreased likelihood of transmurality by 11% (P < 0.05). CONCLUSIONS: The parallel and hinged clamps have different pressure profiles with higher likelihood of transmurality using the parallel clamp. Fat reduces the ability of RF to deliver a transmural lesion. These findings have implications for optimal surgical RF ablation technique.

KW - Ablation

KW - Atrial fibrillation

KW - Contact force

KW - Lesion

KW - Radiofrequency

KW - Surgery

UR - http://www.scopus.com/inward/record.url?scp=85058909797&partnerID=8YFLogxK

U2 - 10.1093/icvts/ivy191

DO - 10.1093/icvts/ivy191

M3 - Article

VL - 28

SP - 85

EP - 93

JO - Interactive cardiovascular and thoracic surgery

T2 - Interactive cardiovascular and thoracic surgery

JF - Interactive cardiovascular and thoracic surgery

SN - 1569-9293

IS - 1

ER -