Tissue ablation is a common medical procedure that involves manipulation of the target tissue with an aim to restore normal structure and function. Ablations are performed throughout the human body for treating various carcinomas and disease conditions. Although a routine clinical procedure, in a small percentage of patients it may cause collateral damage to surrounding structures which can have severe clinical implications. The collateral damage results in altered tissue properties those are dependent on the level of ablative energy and extent of tissue injury. Therefore, assessment of tissue properties is fundamental to advancing the understanding of underlying basic and clinical science of ablations, especially to maximize therapy efficacy and minimize procedural complications. Thus, a thorough understanding of tissue properties is essential to the successful outcome of all ablation procedures.Unique laboratory methodologies were developed that were used to assess the physiological and biomechanical properties of respiratory diaphragm, esophagus, cardiac trabeculae, and vastus lateralis tissues following exposure to five different therapeutic ablative modalities: radiofrequency ablation, cryoablation, high-intensity focused ultrasound, microwave ablation, and chemical ablation (with acetic acid, ethanol, hypertonic sodium chloride, and urea). The changes in physiological properties were quantified by measuring changes in peak force (strength of contractions) and baseline force (resting muscle tension) in response to ablations. The changes in biomechanical properties were quantified by measuring the stress-strain characteristics, avulsion forces, and elastic moduli in response to ablations. Dose effect responses of each ablative modality were quantified. To our knowledge these are the first reports of such methodological comparative assessment of tissue properties following treatment with therapeutic ablative modalities at clinically relevant doses. The understanding of tissue properties has wide applications ranging from applied research to the development of novel tools, ablation techniques, and innovative clinical treatment options. These findings may provide novel insights into the effects of ablations which may allow further improvements in ablative techniques to increase the overall safety and efficacy of ablative procedures. It is clear that the understanding of collateral damage at the cellular level, isolated tissue level, and whole organ level will be important to the future of this evolving era of ablations.
University of Minnesota Ph.D. dissertation. September 2014. Major: Biomedical Engineering. Advisor: Arthur G. Erdman. 1 computer file (PDF); xi, 357 pages, appendices 1-7.
The Comparative assessment of clinical ablative therapies: effects on physiological and biomechanical properties of contractile tissues in response to therapeutic doses.
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