The effects of radiofrequency ablation versus medical therapy on the quality-of-life and exercise capacity in patients with accessory pathway-mediated supraventricular tachycardia: a treatment comparison study

Refined Dual-Phase-Lag Theory for the 1D Behavior of Skin Tissue under Ramp-Type Heating

In this article, a mathematical analysis of thermoelastic skin tissue is presented based on a refined dual-phase-lag (DPL) thermal conduction theory that considers accounting for the effect of multiple time derivatives. The thin skin tissue is regarded as having mechanically clamped surfaces that are one-dimensional. Additionally, the skin tissue undergoes ramp-type heating on its outer surface, whereas its inner surface keeps the assessed temperature from vanishing. Some of the previous generalized thermoelasticity theories were obtained from the proposed model. The distributions of temperature, displacement, dilatation, and stress are attained by applying the Laplace transform and its numerical reversal approaches. The outcomes are explicitly illustrated to examine the significant influences on the distributions of the field variables. The refined DPL bioheat conduction model in this study predicts temperature, and the findings revealed that the model is located among the existing generalized thermoelastic theories. These findings offer a more thorough understanding of how skin tissue behaves when exposed to a particular boundary condition temperature distribution.

The effects of thermal and mechanical material properties on tumorous tissue during hyperthermia treatment

Although there have been numerous reports in several articles about the viscoelastic properties of biological tissues, no effort has been made to investigate the combined thermal and mechanical behavior of the viscoelastic tissue. At present, the model of thermo-viscoelasticity theory with variable thermal conductivity and rheological properties of the volume is considered to investigate bio-thermo-mechanics behavior in living tissue within the context of the Lord-Shulman theory. The model is applied to a limited thickness, cancerous layer problem. The problem was solved analytically in the transformed domain using Laplace transform as a tool. The exact solution is obtained in the context of transformation Laplace. Numerical results are given and illustrated graphically for the distributions of temperature, displacement, and stress. Some correlations are produced with the results obtained for the absence of the thermal relaxation parameter. The effects of variable thermal and volume materials properties, blood perfusion rate on the behavior of various fields are examined.

Quality of life assessment in children before and after a successful ablation for supraventricular tachycardia

BACKGROUND AND OBJECTIVES

Young patients suffering from rhythm disorders have a negative impact in their quality of life. In recent years, ablation has become the first-line therapy for supraventricular arrhythmias in children. In the light of the current expertise and advancement in the field, we decided to evaluate the quality of life in young patients with supraventricular arrhythmias before and after a percutaneous ablation procedure.

METHODS

The prospective cohort consisted of patients <18 years with structurally normal hearts and non-pre-excited supraventricular arrhythmias, who had an ablation in our centre from 2013 to 2018. The cohort was evaluated with the PedsQL™ 4.0 Generic Core Scales self-questionnaire prior to and post-ablation.

RESULTS

The final cohort included 88 patients consisted of 52 males (59%), with a mean age at ablation of 12.5 ± 3.3 years. Forty-two patients (48%) had a retrograde-only accessory pathway mediating the tachycardia, 38 (43%) had atrio-ventricular nodal re-entrant tachycardia, 7 (8%) had ectopic atrial tachycardia, and 1 (1%) had atrial flutter. The main reason for an ablation was the patient's choice in 53%. There were no severe complications. Comparison between the baseline and post-ablation assessments showed that patients reported significant improvement in the scores for physical health, emotional and social functioning, as well as in the total scores.

CONCLUSIONS

The present study demonstrates that the successful treatment of supraventricular arrhythmias by means of an ablation results in a significant improvement in the quality of self-reported life scores in young patients.

Impact of Radiofrequency Ablation and Antiarrhythmic Medications on the Quality of Life of Patients with Supraventricular Tachycardias: Preliminary Validation of the Greek Version of the Umea22 (U22) Questionnaire

Objective

This study aims to (i) translate, culturally adapt, and preliminarily validate the arrhythmia-specific Umea22 (U22) questionnaire and (ii) assess the impact of radiofrequency (RF) ablation and medical treatment on the quality of life of patients with supraventricular tachycardias (SVTs).

Methods

A total of 140 patients with atrioventricular nodal re-entry tachycardia (AVNRT) and atrioventricular re-entry tachycardia (AVRT) were enrolled in the study. Of these, 100 patients underwent RF ablation (group A) and 40 patients were managed with antiarrhythmic medications (group B). Health-related quality of life (HRQoL) was assessed for both groups using the Short Form-36 Health Survey (SF-36) and the arrhythmia-specific Umea22 (U22) questionnaire at baseline and 3-month follow-up. Exploratory and confirmatory factor analyses were performed to assess the validity of the U22 questionnaire. Univariate comparisons of HRQoL scores between study timepoints and multivariate regression analyses adjusting for baseline confounders were conducted.

Results

The factor analysis of the U22 questionnaire yielded a six-factor model (“burden of spells”; “heart contractility”; “character of spells”; “general/non-specific feeling”; “other specific somatic symptoms”; “fear”) with acceptable fit results. Patients of group A showed significant improvement in all SF-36 and U22 scores at 3 months' follow-up compared to baseline (all p<0.05). Patients of group B presented deterioration of the total SF-36 score (p=0.001) and improvement of certain U22 measures, namely, well-being (p=0.004), heartbeat speed, and intensity during arrhythmia spells (p<0.0001 for both measures) at 3 months' follow-up, compared to baseline. Employment status, male sex, and urban residence emerged as important predictors.

Conclusion

The Greek version of the U22 questionnaire is a valid tool to assess SVT-related symptoms. RF ablation appears to exert more pronounced beneficial outcomes on HRQoL of patients with SVTs compared to medical treatment. Prompt referral of patients with SVTs to specialist centers may favorably affect their quality of life and should be encouraged.

Prediction of tissue thermal damage

This paper presents a method to characterize tissue thermal damage by taking into account the thermal-mechanical effect of soft tissues for thermal ablation. This method integrates the bio-heating conduction and non-rigid motion dynamics to describe thermal-mechanical behaviors of soft tissues and further extends the traditional tissue damage model to characterize thermal-mechanical damage of soft tissues. Simulations and comparison analysis demonstrate that the proposed method can effectively predict tissue thermal damage and it also provides reliable guidelines for control of the thermal ablation procedure.

Patient perception of symptoms and quality of life following ablation in patients with supraventricular tachycardia

OBJECTIVES

It remains unclear which symptom experiences and aspects of quality of life (QOL) change after ablation in patients with supraventricular tachycardia (SVT). To determine how patient perceptions of symptoms and QOL change after ablation, we used a single group pretest-posttest design.

METHODS

Patients with SVT (n=52; mean age 41+/-17 years; 65% female) completed generic and disease-specific measures at baseline and 1 month after ablation.

RESULTS

Significant improvement after ablation was noted on virtually all measures (P <.05). Patients reported decreases from baseline regarding frequency and duration of episodes, number of symptoms, and impact of SVT on routine activities. All symptoms decreased in prevalence; however, no symptoms were completely eliminated at 1-month follow-up. Women, more so than men, reported larger changes in symptom and QOL scores after ablation.

CONCLUSIONS

Despite the small sample, statistically significant improvement was found after ablation in a variety of patients with different symptoms and QOL indices.

Sustained high quality of life in a 5-year long term follow-up after successful ablation for supra-ventricular tachycardia. results from a large retrospective patient cohort

INTRODUCTION

The ablation of supraventricular tachycardias (SVT) using radiofrequency energy (RF) is a procedure with a high primary success rate. However, there is a scarcity of data regarding the long term outcome, particularly with respect to quality of life (QoL).

METHODS AND RESULTS

In this retrospective single-center study, 454 patients who underwent ablation of SVT between 2002 and 2007 received a detailed questionnaire addressing matters of QoL. The questionnaire was a modified version of the SF-36 Health Survey questionnaire and the Symptom Checklist--Frequency and Severity Scale.After a mean follow up of 4.5+/-1.3 years, 309 (68.1%) of the contacted 454 patients (269 female, 59.2%, mean age 58+/-6.5) completed the questionnaire. Despite of 27% of relapses in the study group, 91.7% considered the procedure a long-term success. The remainder of patients experienced no change in (3.7%) or worsening of (4.7%) symptoms. There were no significant differences between the various types of SVT (p=1). QoL in patients with Atrio-Ventricular Nodal Reentry Tachycardia (AVNRT) and Atrio-Ventricular Reentry Tachycardia (AVRT) improved significantly (p<0.0005 respectively p<0.043), whereas QoL in patients with Ectopic Atrial Tachycardia (EAT) showed a non-significant trend towards improvement. Main symptoms before ablation, such as tachycardia (91.5%), increased incidence of tachycardia episodes over time (78.1%), anxiety (55.5%) and reduced physical capacity in daily life (52%) were significantly improved after ablation (p<0.0001).

CONCLUSION

The high acute ablation success of SVT persists for years in long term follow up and translates into a significant improvement of QoL in most patients.

In vitro calibration of a system for measurement of in vivo convective heat transfer coefficient in animals

Background

We need a sensor to measure the convective heat transfer coefficient during ablation of the heart or liver.

Methods

We built a minimally invasive instrument to measure the in vivo convective heat transfer coefficient, h in animals, using a Wheatstone-bridge circuit, similar to a hot-wire anemometer circuit. One arm is connected to a steerable catheter sensor whose tip is a 1.9 mm × 3.2 mm thin film resistive temperature detector (RTD) sensor. We used a circulation system to simulate different flow rates at 39°C for in vitro experiments using distilled water, tap water and saline. We heated the sensor approximately 5°C above the fluid temperature. We measured the power consumed by the sensor and the resistance of the sensor during the experiments and analyzed these data to determine the value of the convective heat transfer coefficient at various flow rates.

Results

From 0 to 5 L/min, experimental values of h in W/(m²·K) were for distilled water 5100 to 13000, for tap water 5500 to 12300, and for saline 5400 to 13600. Theoretical values were 1900 to 10700.

Conclusion

We believe this system is the smallest, most accurate method of minimally invasive measurement of in vivo h in animals and provides the least disturbance of flow.

In Vivo Measurement of Swine Endocardial Convective Heat Transfer Coefficient

We measured the endocardial convective heat transfer coefficient h at 22 locations in the cardiac chambers of 15 pigs in vivo. A thin-film Pt catheter tip sensor in a Wheatstone-bridge circuit, similar to a hot wire/film anemometer, measured h. Using fluoroscopy, we could precisely locate the steerable catheter sensor tip and sensor orientation in pigs' cardiac chambers. With flows, h varies from 2500 to 9500 W/m2 x K. With zero flow, h is approximately 2400 W/m2 x K. These values of h can be used for the finite element method modeling of radiofrequency cardiac catheter ablation.

Quality of life before and after radiofrequency catheter ablation in patients with drug refractory atrioventricular nodal reentrant tachycardia

In a retrospective survey of 161 highly symptomatic patients, we found significant improvements in symptoms, patient utility, and use of medical care services after radiofrequency ablation for atrioventricular nodal reentrant tachycardia.

Risk to patients from radiation associated with radiofrequency ablation for supraventricular tachycardia

BACKGROUND

Radiofrequency ablation may be associated with prolonged fluoroscopy times. Previous studies have calculated radiation risks by measuring the radiation dose at a limited number (6) of body sites. This is an inherently inaccurate measure. Our study aimed to quantify more precisely patient-related radiation risks associated with radiofrequency ablation for supraventricular tachycardia.

METHODS AND RESULTS

Nine female patients having radiofrequency ablation for supraventricular tachycardia were studied. The radiation dose was determined at 41 body sites in each patient with the use of thermoluminescent dosimeters and was correlated with that measured simultaneously with a Diamentor dose-area product meter. The estimated mean organ doses (mGy) per 60 minutes of fluoroscopy were: lungs 30.8; bone marrow 4.3; left breast 5.1; right breast 3. 5; and thyroid 2.4. From the average organ doses, the estimated mean total lifetime excess risk of a fatal malignancy was 294 per million cases (0.03%) per 60 minutes of fluoroscopy. The risk calculation from the Diamentor dose-area product and thermoluminescent dosimeters were similar, suggesting that radiation dose was measured accurately. The estimated risk of radiation-induced malignancy increased with increasing body mass index (P=0.03).

CONCLUSIONS

Prolonged fluoroscopy during radiofrequency ablation may potentially cause a small increase in the lifetime risk of fatal malignancy, with lung malignancy being most likely. This risk is small only with the use of techniques and x-ray equipment optimized to keep radiation as low as possible. The risk is increased in obese patients.

Radiofrequency catheter ablation versus medical therapy for initial treatment of supraventricular tachycardia and its impact on quality of life and healthcare costs

We prospectively compared the impact on quality of life and cost effectiveness between ablation and medication as an initial strategy for patients with paroxysmal supraventricular tachycardia (SVT). Seventy-nine consecutive patients with newly documented paroxysmal SVT were treated with either ablation or medication. Health surveys (SF-36 and disease-specific questions) were obtained at baseline and after 12 months of follow up. Cost of health care utilization for the 6 months before and after treatment were measured. Both medication and ablation improved quality of life. However, ablation improved quality of life in more general health categories than medication. At follow up, ablation was associated with significantly improved quality of life in the bodily pain (63+/-24 vs 81+/-20, p <0.005), general health (69+/-21 vs 79+/-21, p <0.05), vitality (55+/-21 vs 66+/-22, p <0.05), and role emotion (78+/-36 vs 94+/-17, p <0.05) categories when compared with medication. Although both medication and ablation decreased frequency of disease-specific symptoms, ablation resulted in complete amelioration of symptoms in more patients (33% vs 74%). Potential long-term costs were similar for medication and ablation. In conclusion, ablation improves health-related quality of life to a greater extent, and in more aspects of general and disease-specific health than medication.

Intraventricular electrogram mapping and radiofrequency cardiac ablation for ventricular tachycardia

Since its first use in the early 1980s, radiofrequency catheter ablation has gained acceptance as primary therapy for many cardiac rhythm disorders. This article reviews fundamentals of cardiac mapping and radiofrequency ablation and their clinical use for treatment of ventricular tachycardia. The review concludes that the use of radiofrequency ablation to cure ventricular tachycardia has consistently increased over the years, as better mapping and ablation tools have been made available to the medical community. Presently, high success and low complication rates are achieved only in patients with bundle branch, idiopathic, or monomorphic and stable ventricular tachycardias. The reviewed studies and reports suggest that, in order to increase the success rates in patients with ventricular tachycardias caused by coronary artery disease, mapping systems that can identify arrhythmogenic pathways more accurately and more efficiently and ablation devices capable of generating larger lesions are needed.