Radiofrequency ablation of atrial flutter: a randomized controlled study of two anatomic approaches

Atrial flutter often results from a macroreentrant circuit that uses anatomic structures within the right atrium as its borders. RF ablation at the site of an obligatory isthmus can eliminate the atrial flutter circuit. The aim of this study was to compare two approaches to atrial flutter ablation: the septal (septal aspect of the tricuspid valve annulus to coronary sinus ostium and Eustachian ridge) approach versus the posterior (inferior vena cava to tricuspid valve annulus) approach. Twenty patients were randomized to either the "septal" or "posterior" approach. Entrainment mapping and/or confirmation of bidirectional isthmus conduction at baseline were performed in those patients in atrial flutter and normal sinus rhythm, respectively. RF ablation was performed with standard catheters and techniques. Crossover was permitted after two lines of RF lesions. Endpoints included acute success rates and fluoroscopy times. There was no statistically significant difference in the success rate between the two approaches using intention-to-treat analysis. Fluoroscopy times in the septal versus posterior approaches were 58.4 +/- 30.3 versus 70.8 +/- 31.1 minutes, respectively (P = 0.7). There was more frequent crossover in patients assigned to the septal approach and the one major complication, atrioventricular block, also occurred using this approach. There was no statistically significant difference in the success rate or fluoroscopy times between the septal and posterior approaches to atrial flutter ablation. However, given the risk of atrioventricular block with the septal approach, the posterior approach should be the preferred initial choice.     

Reversible visual loss in a patient with rheumatoid arthritis and the role of vascular imaging.

Spontaneous vertebral artery dissection is a condition that can have lethal consequences. The condition should be considered in young male patients who present with a stroke. At presentation, headaches, cerebral ischaemic episodes and oculosympathetic paresis are the most commonly encountered manifestations. The diagnosis is confirmed with angiography. Here, we present a middle-aged male gardener with rheumatoid arthritis and signs of vertebral artery dissection to highlight the importance of diagnosis and discuss the controversies in management.     

Race and Health Disparities in Patient Refusal of Surgery for Early-Stage Pancreatic Cancer: An NCDB Cohort Study

Aim

To identify factors associated with refusal of surgery in patients with early-stage pancreatic cancer and estimate the impact of this decision on survival.

Methods

Using the National Cancer Data Base, 26,358 patients were identified with potentially resectable tumors (pretreatment clinical stage I: T1 or T2 N0M0). Multivariate models were employed to identify factors predicting failure to undergo surgery and assess the impact on survival.

Results

Of early-stage patients who were recommended surgery, 7.8% (N?=?992) refused surgery for resectable early-stage pancreatic cancer. On multivariable analysis, patients were more likely to refuse surgery if they were older [odds ratio (OR)?=?1.18; 95% confidence interval (CI) 1.16–1.19], female (OR?=?1.52; 95% CI 1.33–1.73), African American (vs White, OR?=?1.79; 95% CI 1.37–2.34), on Medicare/Medicaid (vs private, OR?=?2.75; 95% CI 1.54–4.92) or had higher Charlson–Deyo score (2 vs 0, OR?=?1.33; 95% CI 1.03–1.72). Patients were also significantly more likely to refuse surgery if they were seen at a center that is not an academic/research program (OR 1.9; 95% CI 1.6–2.27). Patients who were recommended surgery but refused had significantly worse survival than those with stage I who received surgery [median survival 6.8 vs 24 months, Cox hazard ratio (HR) 3.41; 95% CI 3.12–3.60].

Conclusions

The percentage of patients refusing surgery for operable early-stage pancreatic cancer has been decreasing in the last decade but remains a significant issue that affects survival. Disparities in refusal of surgery are independently associated with several variables including gender, race, and insurance. To mitigate national disparities in surgical care, future studies should focus on exploring potential reasons for refusal and developing communication interventions.

     

A randomized controlled trial demonstrates that a novel closed-loop propofol system performs better hypnosis control than manual administration

Purpose

The purpose of this randomized control trial was to determine the performance of a novel rule-based adaptive closed-loop system for propofol administration using the bispectral index (BIS®) and to compare the system’s performance with manual administration. The effectiveness of the closed-loop system to maintain BIS close to a target of 45 was determined and compared with manual administration.

Methods

After Institutional Review Board approval and written consent, 40 patients undergoing major surgery in a tertiary university hospital were allocated to two groups using computer-generated block randomization. In the Closed-loop group (n = 20), closed-loop control was used to maintain anesthesia at a target BIS of 45, and in the Control group (n = 20), propofol was administered manually to maintain the same BIS target. To evaluate each technique’s performance in maintaining a steady level of hypnosis, the BIS values obtained during the surgical procedure were stratified into four clinical performance categories relative to the target BIS: ≤ 10%, 11-20%, 21-30%, or > 30% defined as excellent, good, poor, or inadequate control of hypnosis, respectively. The controller performance was compared using Varvel’s controller performance indices. Data were compared using Fisher’s exact test and the Mann-Whitney U test, P < 0.05 showing statistical significance.

Results

In the Closed-loop group, four females and 16 males (aged 54 ± 20 yr; weight 79 ± 7 kg) underwent anesthesia lasting 143 ± 57 min. During 55%, 29%, 9%, and 7% of the total anesthesia time, the system showed excellent, good, poor, and inadequate control, respectively. In the Control group, five females and 15 males (aged 59 ± 16 yr; weight 75 ± 13 kg) underwent anesthesia lasting 157 ± 81 min. Excellent, good, poor, and inadequate control were noted during 33%, 33%, 15%, and 19% of the total anesthesia time, respectively. In the Closed-loop group, excellent control of anesthesia occurred significantly more often (P < 0.0001), and poor and inadequate control occurred less often than in the Control group (P < 0.01). The median performance error and the median absolute performance error were significantly lower in the Closed-loop group compared with the Control group (-1.1 ± 5.3% vs -10.7 ± 13.1%; P = 0.004 and 9.1 ± 1.9% vs 15.7 ± 7.4%; P < 0.0001, respectively).

Conclusion

The closed-loop system for propofol administration showed better clinical and control system performance than manual administration of propofol. (Clinical Trials gov. NCT 01019746).     

A Noninvasive Clinical Scoring Model Predicts Risk of Nonalcoholic Steatohepatitis in Morbidly Obese Patients

Background  

A simple model to predict nonalcoholic steatohepatitis (NASH) in patients with nonalcoholic fatty liver disease is desirable to optimize the selection of patients for liver biopsy. We investigated a large group of morbidly obese patients to derive a scoring system based on simple clinical and laboratory variables.     

Distension-Induced Gastric Contraction is Attenuated in an Experimental Model of Gastric Restraint

Background  

Gastric distension has important implications for motility and satiety. The hypothesis of this study was that distension affects the amplitude and duration of gastric contraction and that these parameters are largely mediated by efferent vagus stimulation.     

Transcranial magnetic stimulation in different current directions activates separate cortical circuits

Transcranial magnetic stimulation (TMS) to the primary motor cortex (M1) produces a series of corticospinal descending waves, with a direct (D) wave followed by several indirect (I) waves. TMS inducing posterior-anterior (PA) current in the brain predominantly recruits the early I1-wave, whereas anterior-posterior (AP) directed current preferentially recruits the late I3-wave. However, it is not known whether I-waves elicited by different current directions are mediated by the same neuronal populations. We studied the neuronal mechanisms mediating I-waves by examining the influence of short-latency afferent inhibition (SAI) on various I-waves. SAI was tested with electrical median nerve stimulation at the wrist followed by TMS to the contralateral M1 at different current directions. Surface electromyograms and single motor units were recorded from the first dorsal interosseous muscle. SAI was weaker for the AP compared with that for the PA current direction. With increasing median nerve stimulation intensities, SAI increased for the PA direction but showed a U-shaped relationship for the AP direction. SAI produced more inhibition of late I-waves generated by PA than those generated by AP current direction. We conclude that late I-waves generated by PA and AP current directions are mediated by different neuronal mechanisms.     

Gait and balance in essential tremor: Variable effects of bilateral thalamic stimulation

Essential tremor (ET) is a multi‐faceted condition best known for postural and action tremor but also may include disordered gait and postural instability. Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus provides substantial tremor reduction yet some patients with bilateral VIM DBS have gait and balance impairment. This study examines gait and balance performance in 13 participants with ET who have bilateral VIM DBS compared with a matched control group. Participants with ET were tested with their stimulators off (DBS OFF) and on (DBS ON). For both standard and tandem walking, participants with ET walked significantly more slowly than controls, with significantly lower cadence, spending a lower percentage of the gait cycle in single limb support and a higher percentage in double support compared with controls. Participants with ET also had significantly lower tandem and one leg stance times, Berg balance scores, balance confidence, and required significantly greater time to perform the Timed Up‐and‐Go relative to controls. There were no significant differences in any gait or balance measures in the DBS OFF versus DBS ON conditions, but the effects of DBS on gait and balance were highly variable among individuals. Future studies are needed to determine why some individuals experience gait and balance difficulties after bilateral thalamic DBS and others do not. A better understanding of the mechanisms underlying gait and balance impairments in those with bilateral DBS is critical to reduce falls and fractures in this group. © 2008 Movement Disorder Society