Cardiac tissue ablation with catheter-based microwave heating

The common condition of atrial fibrillation is often treated by cutting diseased cardiac tissue to disrupt abnormal electrical conduction pathways. Heating abnormal tissue with electromagnetic power provides a minimally invasive surgical alternative to treat these cardiac arrhythmias. Radio frequency ablation has become the method of choice of many physicians. Recently, microwave power has also been shown to have great therapeutic benefit in medical treatment requiring precise heating of biological tissue. Since microwave power tends to be deposited throughout the volume of biological media, microwave heating offers advantages over other heating modalities that tend to heat primarily the contacting surface. It is also possible to heat a deeper volume of tissue with more precise control using microwaves than with purely thermal conduction or RF electrode heating. Microwave Cardiac Ablation (MCA) is used to treat heart tissue that allows abnormal electrical conduction by heating it to the point of inactivation. Microwave antennas that fit within catheter systems can be positioned close to diseased tissue. Specialized antenna designs that unfurl from the catheter within the heart can then radiate specifically shaped fields, which overcome problems such as excessive surface heating at the contact point. The state of the art in MCA is reviewed in this paper and a novel catheter-based unfurling wide aperture antenna is described. This antenna consists of the centre conductor of a coaxial line, shaped into a spiral and insulated from blood and tissue by a non-conductive fluid filled balloon. Initially stretched straight inside a catheter for transluminal guiding, once in place at the cardiac target, the coiled spiral antenna is advanced into the inflated balloon. Power is applied in the range of 50–150 W at the reserved industrial, scientific and medical (ISM) frequency of 915 MHz for 30–90 s to create an irreversible lesion. The antenna is then retracted back into the catheter for removal. Simulated and experimental measurements on phantoms, in vitro animal organ tissue and living animals have shown that these microwave applicators deliver the intended therapeutic lesions that are both wider and deeper than those generated by RF ablation or other recently reported microwave applicators.

[1]  J. Langberg,et al.  Radiofrequency Catheter Ablation of Ventricular Tachycardia in Patients With Coronary Artery Disease , 1993, Circulation.

[2]  N. Smedira,et al.  Microwave ablation of atrial fibrillation during mitral valve operations. , 2002, The Annals of thoracic surgery.

[3]  S. Tugtekin,et al.  Intraoperative microwave ablation for curative treatment of atrial fibrillation in open heart surgery--the MICRO-STAF and MICRO-PASS pilot trial. MICROwave Application in Surgical treatment of Atrial Fibrillation. MICROwave Application for the Treatment of Atrial Fibrillation in Bypass-Surgery. , 1999, The Thoracic and cardiovascular surgeon.

[4]  C Gabriel,et al.  The dielectric properties of biological tissues: I. Literature survey. , 1996, Physics in medicine and biology.

[5]  Eugene H Blackstone,et al.  Atrial fibrillation: current surgical options and their assessment. , 2002, The Annals of thoracic surgery.

[6]  D. Haines,et al.  Microwave catheter ablation of myocardium in vitro. Assessment of the characteristics of tissue heating and injury. , 1994, Circulation.

[7]  Stuchly,et al.  DIELECTRIC PROPERTIES OF BIOLOGICAL SUBSTANCES–TABULATED , 1980 .

[8]  J. C. Lin,et al.  Microwave catheter ablation of the atrioventricular junction in closed-chest dogs , 1996, Medical and Biological Engineering and Computing.

[9]  A. Guy,et al.  Nonionizing electromagnetic wave effects in biological materials and systems , 1972 .

[10]  A. Saltman,et al.  A completely endoscopic approach to microwave ablation for atrial fibrillation. , 2003, The heart surgery forum.

[11]  Herman P. Schwan,et al.  RADIATION BIOLOGY, MEDICAL APPLICATIONS, AND RADIATION HAZARDS. , 1968 .

[12]  P. Stauffer,et al.  Implantable helical coil microwave antenna for interstitial hyperthermia. , 1988, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[13]  T. W. Athey,et al.  Measurement of Radio Frequency Permittivity of Biological Tissues with an Open-Ended Coaxial Line: Part II - Experimental Results , 1982 .

[14]  J. Langberg,et al.  Ablation of the atrioventricular junction with radiofrequency energy using a new electrode catheter. , 1991, The American journal of cardiology.

[15]  J. Strohbehn,et al.  A Method for Measurement of the Permittivity of Thin Samples , 1979 .

[16]  J. Ruskin,et al.  Treatment of ventricular tachycardia by transcatheter radiofrequency ablation in patients with ischemic heart disease. , 1994, Circulation.

[17]  D. Wilber,et al.  Radiofrequency catheter ablation of cardiac arrhythmias : basic concepts and clinical applications , 1995 .

[18]  J. Langberg,et al.  Catheter Ablation of the Atrioventricular Junction Using a Helical Microwave Antenna: A Novel Means of Coupling Energy to the Endocardium , 1991, Pacing and clinical electrophysiology : PACE.

[19]  J. C. Lin,et al.  Catheter microwave ablation therapy for cardiac arrhythmias. , 1999, Bioelectromagnetics.

[20]  L. Horowitz,et al.  Ventricular resection guided by epicardial and endocardial mapping for treatment of recurrent ventricular tachycardia. , 1980, The New England journal of medicine.

[21]  C. Rappaport,et al.  A 2 1/4-turn spiral antenna for catheter cardiac ablation , 1999, IEEE Transactions on Biomedical Engineering.

[22]  R. Gallotti,et al.  Left main coronary arterial lesion after microwave epicardial ablation. , 2003, The Annals of thoracic surgery.

[23]  Carey M. Rappaport,et al.  Simulated biological materials at microwave frequencies for the study of electromagnetic hyperthermia , 1992, 1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[24]  P. Stauffer,et al.  Evaluation of microwave and radio frequency catheter ablation in a myocardium-equivalent phantom model , 1992, IEEE Transactions on Biomedical Engineering.

[25]  Electromagnetic Syringe , 1978, IEEE Transactions on Biomedical Engineering.

[26]  M. Griem.  New Frontiers in Medical Device Technology , 1996 .

[27]  S. B. Field,et al.  An Introduction to the Practical Aspects of Clinical Hyperthermia , 1990 .

[28]  Michael Knaut,et al.  Application of microwave energy in cardiac tissue ablation: from in vitro analyses to clinical use. , 2002, The Annals of thoracic surgery.

[29]  K. Kuck,et al.  Catheter Ablation of Atrioventricular Junction Using Radiofrequency Current in 17 Patients: Comparison of Standard and Large‐Tip Catheter Electrodes , 1991, Circulation.

[30]  J. Maessen,et al.  Beating-heart surgical treatment of atrial fibrillation with microwave ablation. , 2002, The Annals of thoracic surgery.

[31]  Paul J. Wang,et al.  Microwave Ablation Using a Spiral Antenna Design in a Porcine Thigh Muscle Preparation: In Vivo Assessment of Temperature Profile and Lesion Geometry , 2000, Journal of cardiovascular electrophysiology.

[32]  A. W. Guy,et al.  Analyses of Electromagnetic Fields Induced in Biological Tissues by Thermographic Studies on Equivalent Phantom Models , 1971 .

[33]  P. J. Wang,et al.  Development and experimental verification of the wide-aperture catheter-based microwave cardiac ablation antenna , 2000 .

[34]  J Clémenty,et al.  Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. , 1998, The New England journal of medicine.