Safety considerations for magnetic resonance imaging of pacemaker and ICD patients

Summary Magnetic resonance imaging (MRI) has evolved as an important diagnostic tool in medicine. However, due to safety concerns the presence of an implanted cardiac pacemaker is considered to be a contraindication to MRI in most medical centers. Previous in vitro and in vivo studies showed that strong electromagnetic fields in the MRI environment may cause asynchronous pacing, inhibition of a demand pacemaker, induced currents in the pacemaker system and pacing of the heart, or potential risk of thermal myocardial injury around the pacing lead tip. ICDs in addition are not able to charge and apply a therapy in the strong magnetic field. There are reported lethal consequences of MRI in patients with pacemakers. However, there are also recent reports of small series of pacemaker patients who have safely undergone MRI. At present time, non-MRI modalities should be considered, whenever possible, to make a diagnosis in pacemaker recipients. If other imaging modalities are not adequate, MRI at low field strengths (0.5 Tesla or less) with careful monitoring and preparation for adverse events may be considered only in experienced centers. The device should be programmed to an asynchronous, or if possible to a non-pacing mode, during MRI. Pacemaker mode changes, inappropriate pacing behavior due to induced voltages, and localized heating at the lead tip are the primary issues that remain to be fully investigated in future studies.This work is supported by a grant from the Bakken Research Center, Medtronic Inc., Maastricht, the Netherlands.     

Determining the effectiveness of various treatment modalities in carpal tunnel syndrome by ultrasonography and comparing ultrasonographic findings with other outcomes

Firstly, we aimed to determine the effectiveness of various treatment modalities using ultrasonography (US), and secondly, we aimed to assess the correlations between the ultrasonographic findings and electrophysiological tests, symptom severity, functional status and physical findings. 74 hands of 47 patients with carpal tunnel syndrome (CTS) were randomly treated by applying wrist splinting alone in the neutral position (23 hands), phonophoresis with corticosteroid (PCS) (28 hands) and phonophoresis with non-steroid anti-inflamatory drug (PNSAI) (23 hands). The cross-sectional area (CSA) of the median nerve (MN) was determined by ultrasound on the initial and at the 3?months after treatment. MN conduction studies were performed on the initial visit and 3?months after treatment. The patients completed the Boston symptom severity questionnaire. For clinical evaluation, we used Phalen's and Tinel's signs. We could find reduction in CSA of MN in PCS group (P??0.05) and also between ultrasonographic parameters and BQ scores (P?>?0.05). Although there was some improvement in clinical parameters, ultrasonographic parameters did not change in P-NSAI group. Conclusion: The most effective treatment modality was P-CS according to ultrasonographic and other findings. Although there were inverse correlations between the CSA of MN and sensory and motor MN conduction velocity, no relationship was found between symptom severity, functional status and US findings or electrophysiological studies.     

Right coronary artery originating from distal left circumflex: an extremely rare variety of single coronary artery

Single coronary artery is a rare congenital anomaly of the coronary circulation which is often associated with other congenital cardiac malformations. Right coronary artery arising from the distal left circumflex artery is an extremely rare variety of single coronary artery. We report a patient with a single coronary artery system, in whom the right coronary artery originated from the distal left circumflex. No other associated cardiac anomaly was detected.     

Endothelin and cardiac arrhythmias: do endothelin antagonists have a therapeutic potential as antiarrhythmic drugs?

Endothelin-1 (ET-1), the predominant isoform of the ET peptide family and a potent vasoconstrictor, has been shown to aggravate ischemia-induced ventricular arrhythmias. However, there is also evidence that ET-1 may have a direct arrhythmogenic action that is not solely attributable to myocardial ischemia. Proposed mechanisms for the arrhythmogenic effects of ET-1 are prolongation or increased dispersion of monophasic action potential duration, QT prolongation, development of early afterdepolarizations, acidosis, and augmentation of cellular injury. As for an ionic basis for the observed electrophysiologic effects, ET-induced Ca(2+) release from intracellular stores, generation of inositol triphosphate, inhibition of delayed rectifier K(+) current, and stimulation of the Na(+)/H(+) exchanger may be involved. Recently, some studies have shown that ET receptor antagonists, which promise to be powerful tools in cardiovascular medicine, may also demonstrate antiarrhythmic properties. This review describes the current state of knowledge on the interactions between the ET system and cardiac arrhythmias, and discusses the therapeutic potential of ET antagonists as antiarrhythmic drugs.     

Do All Antioxidant Supplements Have the Same Potential Effect on Preventing Myringosclerosis?

ObjectivesMyringosclerosis is an irreversible pathological healing mechanism of the tympanic membrane which can result in the formation of sclerotic plaques. Antioxidant treatment is a recognised prevention therapy and coenzyme Q10 (CoQ10), lycopene, and grape seed extract (GSE), were used in this manner.MethodsForty-four Wistar rats were used in this experiment, and, following myringotomies, the animals were randomly divided into four groups. CoQ10, lycopene or GSE was administered orally to the respective groups, starting from the day of surgery. Otomicroscopy examination was performed on the 14th day. All tympanic membrane lesions were evaluated and compared otomicroscopically and histopathologically.ResultsThe otomicroscopy and histopathological findings, compared against a control (saline) group, showed the CoQ10, lycopene, and GSE groups had statistically significant differences of degree of sclerosis (P<0.001).ConclusionCoQ10, lycopene, and GSE were compared against a saline group and their antioxidative and anti-inflammatory effects were similar. The formation of myringosclerotic plagues after experimental myringotomy in rats significantly decreased and diminished after systemic administration of the three different antioxidant supplements.     

Autonomic effects of radiofrequency catheter ablation.

Radiofrequency (RF) catheter ablation has become the treatment of choice for a variety of supraventricular tachycardias. Autonomic dysfunction may occur during application of RF current; these abnormalities resolve quickly when current delivery is terminated. We present a case of sinus node arrest and AV block in a 69-year-old woman induced by RF catheter ablation of an AV nodal slow pathway. The proposed mechanisms are a Bezold-Jarisch-like phenomenon or paradoxical activation of cardiac C fibres by direct neural sympathetic stimulation or RF-induced myocardial injury. Based on a review of previously published reports, autonomic effects of RF ablation are discussed.     

A case of generalized allergic contact dermatitis after laser tattoo removal

Tattoos are popular body decorations mainly done for cosmetic purposes. Regarded as a form of self-expression, tattoos reflect the character of the person wearing it. However, as tatoos are persistent visual markings on the body, frequently misperceived by the others causing tattooed to seek removal. Today most of the tattoos can be successfully treated with laser ablation. Here we present a case of generalized allergic contact dermatitis after laser tattoo removal which is a rare adverse reaction of laser tattoo removal.