Thermal therapy, part 2: hyperthermia techniques

Hyperthermia, the procedure of raising the temperature of a part of or the whole body above normal for a defined period of time, is applied alone or as an adjunctive with various established cancer treatment modalities such as radiotherapy and chemotherapy. Clinical hyperthermia falls into three broad categories, namely, (1) localized hyperthermia, (2) regional hyperthermia, and (3) whole-body hyperthermia (WBH). Because of the various problems associated with each type of treatment, different heating techniques have evolved. In this article, background information on the biological rationale and current status of technologies concerning heating equipment for the application of hyperthermia to human cancer treatment are provided. The results of combinations of other modalities such as radiotherapy or chemotherapy with hyperthermia as a new treatment strategy are summarized. The article concludes with a discussion of challenges and opportunities for the future.     

Secondary implantation of implantable collamer lens (ICL) for correction of anisometropic hyperopia in a 3-year-old pseudophakic child

We report the first case of secondary implantation of implantable collamer lens (ICL) for correction of anisometropic hyperopia in a 3-year-old pseudophakic child. The ICL implantation was considered in our patient due to parental noncompliance for contact lens and spectacles use for one year. In terms of efficacy, the preoperative refractive error of +7.00–1.75 diopter (D) reduced to +1.00–1.75 D. The uncorrected distance visual acuity (UDVA) significantly improved from 20/400 (preoperatively) to 20/50 (postoperatively). In terms of safety, after an uneventful implantation surgery, the ICL was well tolerated, and remained well centered, with no serious postoperative complications encountered over a 22-month follow-up.     

Thermal therapy, part 1: an introduction to thermal therapy

Thermal therapy is widely known and electromagnetic (EM) energy, ultrasonic waves, and other thermal-conduction-based devices have been used as heating sources. In particular, advances in EM technology have paved the way for promising trends in thermotherapeutical applications such as oncology, physiotherapy, urology, cardiology, ophthalmology, and in other areas of medicine as well. This series of articles is generally written for oncologists, cancer researchers, medical students, biomedical researchers, clinicians, and others who have an interest in this topic. This article reviews key processes and developments in thermal therapy with emphasis on two techniques, namely, hyperthermia [including long-term low-temperature hyperthermia (40-41 degrees C for 6-72 hr), moderate-temperature hyperthermia (42-45 degrees C for 15-60 min), and thermal ablation, or high-temperature hyperthermia (> 50 degrees C for > 4-6 min)]. The article will also provide an overview of a wide range of possible mechanisms and biological effects of heat. This information will be discussed in light of what is known about the degree of temperature rise that is expected from various sources of energy. The review concludes with an evaluation of human exposure risk to EM energy or the corresponding heat, trends in equipment development, and future research directions.     

Microbial biofilms: their development and significance for medical device-related infections.

Microbial adhesion and biofilm formation on medical devices represent a common occurrence that can lead to serious illness and death. The process by which bacteria and yeast colonize open and closed implants is fairly complicated and involves a series of steps commencing with deposition of host substances onto the material. Prevention and treatment of established biofilms with antimicrobial agents are difficult because the organisms are encased within a protected microenvironment. Efforts to reduce adhesion using specially developed materials, such as hydrophilic or heparin coated, have had modest success once applied to the patient. The reason, at least for the most part, is the diverse milieu into which devices are placed and the multitude of ways in which organisms can colonize surfaces. A better understanding of the process is required, and the knowledge gained must be used to devise new strategies as alternatives to the traditional employment of antibiotics. These new approaches may still use antibiotics but at different concentrations (low to prevent and high to treat infection) and in a different manner (perhaps spiked therapy in which there is a delay between doses to reduce the risk of drug resistance and impact on normal flora). The possibility of applying functional foods to patient management should also be pursued.     

Mid-term results of stentless bioprosthesis for aortic valve replacement. Experience in a series of 97 patients

Stentless bioprostheses have been described as valve substitutes of interest for aortic valvular replacement. We studied 97 consecutive patients with a mean age of 72.2 years (40-84) who underwent aortic valvular replacement with 80 Toronto SPV and 17 Freestyle prostheses. Operative mortality was 6.2. With a mean follow-up of 19 +/- 10 months (1-46), 87.2% of the surviving 86 patients underwent an echocardiography performed by the same operator. Mean gradient was 10.9 +/- 3.6 mmHg (4.2-22.6) and effective orifice area was 1.8 +/- 0.5 cm2 (0.8-3.0) for the 75 controlled stentless valves. The best haemodynamic data were obtained with the 25 mm diameter prostheses. One asymptomatic partial dehiscence was observed during monitoring. None of the 15 detected aortic leaks was significant. We observed a significant reduction of the ventricular mass in 41 patients who had undergone pre- and postoperative evaluation (p < 0.0014). Overall survival was 86.8 +/- 4.4% at 2 years. Stentless bioprostheses offered satisfactory haemodynamic results in our series. They however require an implantation technique learning curve as well as a thorough knowledge of the aortic root anatomy and physiology.     

Behcet’s disease presenting as intracranial hypertension due to cerebral venous thrombosis

The non-parenchymal central nervous system’s (CNS) involvement in Behcet’s disease (BD) is considered rare. We herein report a case of BD complicated by intracranial hypertension (ICH) due to cerebral venous thrombosis (CVT) in a 25-year-old Saudi male. Our patient presented with a four-week history of increasingly severe headache, nausea and diplopia, which were preceded by previous recurrent intermittent oral and genital ulcers, history suggestive of acneiform lesions and arthralgia over the past two years. Ophthalmic examination disclosed normal visual acuity (20/20) in both eyes with bilateral 6th nerve palsy and papilledema. Both eyes showed no signs of anterior or posterior segment inflammation. Oral and genital ulcers were found on physical examination with no other lesions. Magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) of the brain showed lack of flow in the right transverse and sigmoid dural sinuses suggestive of venous thrombosis. On lumbar puncture, the opening pressure was greatly raised. After a comprehensive screening for prothrombotic conditions, a diagnosis of BD with ICH due to CVT was made. The patient was then treated by oral prednisolone, azathioprine, colchicine, cyclosporine, as well as anticoagulation, which resulted in significant clinical improvement.     

Cryoballoon vs radiofrequency ablation of atrial fibrillation: insights from the Veterans Healthcare System

Purpose

Catheter ablation is considered the mainstay treatment for drug-refractory atrial fibrillation (AF). The aims of our study were to compare the efficacy and safety of the most two currently approved approaches (point-by-point radiofrequency ablation (RFA), either with contact force (CF) or without contact force (nCF) catheters, and cryoballoon ablation (CBA)) in the Veterans Healthcare System.

Methods

We performed a retrospective study of patients who underwent ablation for treatment of AF at the veterans affairs healthcare system between 2013 and 2018. Only the first reported ablation procedure was included.

Results

We included 956 patients in the study (97.4% males, 91.5% Caucasians, 67% paroxysmal AF), with 682 patients in RFA-nCF, 139 in RFA-CF, and 135 in CBA. Thirty-day complication rates were comparable between the three groups with the exception of higher incidence of phrenic nerve injury in CBA group when compared to RFA-nCF (2.2% vs 0.0%, p < 0.01). Long-term recurrence rate of AF was significantly lower in the CBA group when compared to RFA-nCF (33.3% vs 47.7%, adjusted HR 0.60, 95% CI 0.44–0.83, p < 0.01). On the other hand, it was similar between RFA-CF and RFA-nCF groups (43.9% vs 47.7%, adjusted HR 1.01, 95% CI 0.76–1.33, p 0.97). After stratifying patients based on AF type, these findings were only present in patients with paroxysmal AF.

Conclusion

CBA for paroxysmal AF, in male dominant patients’ population, was associated with lower incidence of AF recurrence rate while having a comparable safety profile to RFA independent of the use of CF catheters.