Device-based Treatments Research Articles

Renal Denervation Therapy (RDT) in Resistant Hypertension

Resistant hypertension is defined as blood pressure that remains above therapeutic goal despite the use of three antihypertensive drugs including a diuretic. As much as one third of patients with arterial hypertension are treatmentrefractory as they do not reach sufficient blood pressure control despite combination antihypertensive therapy of significant duration. The hyperactivity of sympathetic nervous system (SNS) in the occurrence of treatment-resistant long standing hypertension has been established both in animal models and in clinical practice. In these patients, the kidneys play a central role as an activator of the sympathetic nervous system. The failure of purely pharmacological approaches to treat resistant hypertension has stimulated interest in invasive device-based treatments based on old concepts. In the absence of orally active antihypertensive agents, patients with severe and complicated hypertension were widely treated by surgical denervation of the kidneys until the 1960s, but this approach was associated with a high incidence of severe adverse events and a high mortality rate. A new catheter system using radiofrequency energy has been developed, allowing an endovascular approach to renal denervation and providing patients, with resistant hypertension, with a new therapeutic option that is minimally invasive and can be performed rapidly under local anaesthesia. With this method the afferent and efferent sympathetic nervous fibers surrounding the renal artery are ablated precisely keeping the renal artery intact. To date, this technique has been evaluated only in open-label trials including small numbers of highly selected resistant hypertensive patients with suitable renal artery anatomy. The available evidence suggests a significant and persistent blood pressure-lowering effect and a very low incidence of short & long term complications with no deleterious effects on renal function. These data, although promising, need confirmation in larger randomized controlled clinical trials with longerterm follow-up.DOI: http://dx.doi.org/10.3329/birdem.v2i2.12325(Birdem Med J 2012; 2(2): 104-112)

Review and Comparison of Somatic Therapies

Over the past two decades, the number of somatic treatments for psychiatric disorders has expanded, leading to new insights into the complex relationship between chemical and electric transmission of signals in the brain. In this article, the authors discuss the different device-based treatments currently available in psychiatry. They review clinical indications; putative mechanism of action; efficacy and adverse effects; the results and limitations of salient clinical trials; and active areas of research into the neurobiology of device-based stimuli.

Electromagnetic depression treatment nears approval

Deep transcranial magnetic stimulation adds to psychiatry's arsenal of electronic remedies — A new type of brain stimulation device for combating difficult-to-treat cases of major depressive disorder is likely to break into the large American market soon. Its maker, Jerusalem-based Brainsway, plans to apply to the U.S. Food and Drug Administration for permission to market the device this month. The move follows initial results from a large-scale trial of the system, in which 30.4 percent of treated patients went into remission and 36.7 percent showed significant improvement. Research into devicebased treatments for psychiatric problems has grown rapidly, and if the FDA gives its go-ahead, Brainsway's system will become the fourth device-based therapy to go on the market since 2005.

Advances in syncope

Syncope is a sudden transient loss of consciousness associated with loss of postural tone, caused by bradycardia, tachycardia, or abnormal autonomic reflexes. Pacing and implantable defibrillators treat but do not cure arrhythmias. Reflex syncope has remained a therapeutic challenge. Remarkably, recent advances in the treatment of the reflex syncopal syndromes are (1) the recognition that many pharmacologic and device-based treatments do not really work, (2) complex subdivisions among the reflex syncope types can be simplified, and (3) effective therapies are often common sense applications of behavioral modifications and physical maneuvers. Many of the treatments have been available for decades and have been supplemented by a renewed interest in the physiologic approach while maintaining a role for evidence-based pharmacologic and device-based therapy. Streamlined workups in dedicated syncope centers may be effective, both economically and therapeutically. In the long term, important advances in syncope are likely to come from the still embryonic field of genetics. Beyond genetic counseling, the greatest benefits lie in the future.

Dynamic optimization of chronic migraine treatment

Comparator studies that assess treatment effects in a clinical setting have improved the understanding of the efficacy and tolerability of prophylactic treatments for chronic migraine (CM). It is premature to recommend device-based treatments, such as occipital nerve stimulation, vagal nerve stimulation, and patent foramen ovale closure for CM, because clinical trials are in the preliminary stages. Physical therapy techniques, like applying heat or cold packs, ultrasonography, and electrical stimulation, have been shown to lessen pain. Nonpharmacologic treatments, including cognitive behavioral therapy, stress management, and biofeedback, have been investigated and proved effective in some areas of pain management, including migraine. However, pharmacologic interventions may be necessary for effective, long-term prophylaxis. Several medications under investigation, including topiramate, gabapentin, tizanidine, and amitriptyline, have proved efficacious in reducing the number of migraine episodes and the pain associated with migraine, although adverse events may prevent continued use of some agents. Evidence supports the use of botulinum toxin type A (BoNT-A) for CM, with or without medication overuse, to achieve a significant reduction in headache episodes. Efficacy of BoNT-A for CM is comparable with or better than that of valproate and topiramate, with better tolerability. Predictors of response to BoNT-A for CM appear to include predominantly unilateral location of the headache and the presence of cutaneous or muscle allodynia. BoNT-A has been demonstrated to be safe and well tolerated, with rare discontinuations due to adverse events. Recent clinical trials indicate that rational combination therapy may have a place in treating refractory CM. Well-controlled multicenter trials are awaited.

Detection of Repolarization Alternans With an Implantable Cardioverter Defibrillator Lead in a Porcine Model

Mechanistic links have been suggested between repolarization alternans (RPA) and the onset of ventricular tachycardia (VT) and/or fibrillation. Endocardial detection of RPA may, therefore, be an important step in future device-based treatments of arrhythmias. Here, we investigate if RPA could be detected during acute ischemia using an implantable cardioverter defibrillator (ICD) lead (tip to distal coil) located in the right ventricular apex. In 18 pigs, the right coronary (n = 10) or left anterior descending coronary (n = 8) artery was occluded for 10 min using a balloon catheter, followed by reperfusion for 30 min, and re-occlusion for 30 min. RPA magnitude, computed using the modified moving average (MMA) method, showed a sharp increase in all 18 animals, from a mean baseline level of 1.9 +/- 1.3 mV to 3.0 +/- 1.3 mV during first occlusion (p < 0.001). RPA magnitude showed a prominent increase in 10 animals during re-occlusion, from a mean baseline level of 1.7 +/- 1.0 mV to 3.3 +/- 1.5 mV (p < 0.001). The protocol was terminated during the first two stages of occlusion and reperfusion for the remaining 8 animals due to the occurrence of ventricular fibrillation (VF). These results confirm that RPA increases under ischemic conditions and that it is possible to detect and track RPA dynamics with an ICD lead that is positioned in a clinically realistic location. Such an approach may be useful in formulating improved arrhythmia detection and control algorithms.