Single-center experience of a quadripolar pacing lead for cardiac resynchronization therapy

AIM

Recent studies have shown that a quadripolar left ventricular (LV) lead can result in low rates of dislocation and phrenic nerve stimulation (PNS) acutely and on medium-term follow-up in cardiac resynchronization therapy (CRT). We evaluated the outcomes of CRT patients in whom a quadripolar LV lead was implanted in our institution.

Methods

We studied 45 consecutive heart failure patients (75 % men; age, 70.3?±?9.0 years) following successful implantation of a quadripolar LV lead. Demographic and clinical data were collected preoperatively, and patients were followed up for 18.9 months.

Results

The implantation success rate was 100 %. Mean overall duration was 100.1?±?34.6 min, and X-ray exposure time was 13.20?±?13.5 min. The most distal effective pacing site was used as the final pacing configuration in all patients. Acute dislodgment requiring reoperation occurred before discharge in three cases (6.6 %). Six patients (13 %) suffered PNS during follow-up; we solved this problem by changing the stimulation vector. Three months after implantation, a mean of six out of ten effective sites (threshold <2.5 V at 1.5 ms, no PNS) per patient was recorded.

Conclusions

Over the relatively long term, the quadripolar LV lead was associated with excellent pacing thresholds and low rates of dislocation and PNS.     

Effect of cardiac resynchronization therapy on cardiotrophin-1 circulating levels in patients with heart failure

Cardiotrophin-1 (CT-1) is a member of the interleukin (IL-6) family of cytokines. Plasma CT-1 levels correlate with the left ventricle mass index in patients with dilatated cardiomyopathy and congestive heart failure (CHF). The aim of this paper was to evaluate CT-1 plasma levels, before and after cardiac resynchronization therapy CRT, and to characterizeits prognostic role in patients with CHF. Fifty-two consecutive patients (M/F = 39/13; 56 ± 11 years old) underwent clinical and echocardiographic evaluation, and blood sample collection at baseline. The same evaluation was repeated 6.4 ± 0.79 months after CRT. Patients with a decreased LV end-systolic volume by at least 15% (reverse remodeling) were considered echo responders to CRT. Twenty-nine patients (56%) were responders to CRT. After CRT, only 15 patients (29%) showed increased CT-1 after CRT. They were all non responders to CRT. A multivariate, logistic modelshowed CT-1 as an independent predictor of CRT echo response (p = 0.005; OR 0.97). During follow-up (18 ± 7 months), 21 cardiac events in 18 patients occurred. A Cox multivariable model showed plasma BNP pre-CRT (p = 0.02; CI 1.2–5.6; OR 3.1) and CT1 post-CRT (p = 0.01; CI 1.4–4.3; OR 2.7) as independent predictors of cardiac events. Analysis of CT-1 plasma levels deserves future consideration for larger, longitudinal studies in patients with CHF.     

Can ultrasound guidance reduce the risk of pneumothorax following thoracentesis?,

OBJECTIVE:

Thoracentesis is one of the bedside procedures most commonly associated with iatrogenic complications, particularly pneumothorax. Various risk factors for complications associated with thoracentesis have recently been identified, including an inexperienced operator; an inadequate or inexperienced support team; the lack of a standardized protocol; and the lack of ultrasound guidance. We sought to determine whether ultrasound-guided thoracentesis can reduce the risk of pneumothorax and improve outcomes (fewer procedures without fluid removal and greater volumes of fluid removed during the procedures). In our comparison of thoracentesis with and without ultrasound guidance, all procedures were performed by a team of expert pulmonologists, using the same standardized protocol in both conditions.

METHODS:

A total of 160 participants were randomly allocated to undergo thoracentesis with or without ultrasound guidance (n = 80 per group). The primary outcome was pneumothorax following thoracentesis. Secondary outcomes included the number of procedures without fluid removal and the volume of fluid drained during the procedure.

RESULTS:

Pneumothorax occurred in 1 of the 80 patients who underwent ultrasound-guided thoracentesis and in 10 of the 80 patients who underwent thoracentesis without ultrasound guidance, the difference being statistically significant (p = 0.009). Fluid was removed in 79 of the 80 procedures performed with ultrasound guidance and in 72 of the 80 procedures performed without it. The mean volume of fluid drained was larger during the former than during the latter (960 ± 500 mL vs. 770 ± 480 mL), the difference being statistically significant (p = 0.03).

CONCLUSIONS:

Ultrasound guidance increases the yield of thoracentesis and reduces the risk of post-procedure pneumothorax. (Chinese Clinical Trial Registry identifier: ChiCTR-TRC-12002174 [http://www.chictr.org/en/])     

Individual variability in functional connectivity predicts performance of a perceptual task

People differ in their ability to perform novel perceptual tasks, both during initial exposure and in the rate of improvement with practice. It is also known that regions of the brain recruited by particular tasks change their activity during learning. Here we investigate neural signals predictive of individual variability in performance. We used resting-state functional MRI to assess functional connectivity before training on a novel visual discrimination task. Subsequent task performance was related to functional connectivity measures within portions of visual cortex and between visual cortex and prefrontal association areas. Our results indicate that individual differences in performing novel perceptual tasks can be related to individual differences in spontaneous cortical activity.     

Reduced habituation of the retinal ganglion cell response to sustained pattern stimulation in multiple sclerosis patients

ObjectiveSustained pattern stimulation in normal subjects induces adaptive changes in pattern electroretinogram (PERG), an effect that has been interpreted as a response of glial cells and retinal ganglion cells (RGC). The aim of this study was to compare the effect in normal subjects and in multiple sclerosis patients without previous optic neuritis.MethodsPERGs were elicited by a 7.5 Hz pattern stimulus, presented continuously over 152 s. Response cycles were averaged in 20 packets of 60 events each and amplitude and phase of the 2nd harmonic response was measured. Adaptive changes are expressed as amplitude reduction over the full examination time.ResultsIn normal subjects PERG amplitude declined progressively to a plateau (dA = ?0.46 μV, SE = 0.09 μV); in patients the effect size was severely reduced (dA = ?0.20 μV, SE = 0.04 μV). No significant difference was found in mean amplitude.ConclusionsThe results show reduced RGC habituation in patients, suggesting an abnormal gain and sensitivity control in the inner retina, even in absence of clinical optic neuritis. Recent findings in astrocyte biology and indications drawn from a mathematical model point to a key role of glial cells in this process.SignificanceThe proposed methodology may have implications in the assessment of MS patients and in understanding the pathophysiology of neurological and retinal disorders.     

Iron and steatohepatitis

As the main iron storage site in the body and the main source of the iron-regulatory hormone, hepcidin, the liver plays a pivotal role in iron homeostasis. A variable degree of hepatic iron accumulation has long been recognized in a number of chronic liver diseases. Both alcoholic and non-alcoholic steatohepatitis display increased iron deposits in the liver, with an hepatocellular, mesenchymal, or mixed pattern, and recent reports have documented a concomitant aberrant hepcidin expression that could be linked to different coincidental pathogenic events (e.g. the etiological agent itself, necroinflammation, metabolic derangements, genetic predisposition). The present study reviews the pathogenic mechanisms of iron accumulation in steatohepatitis during alcoholic and non-alcoholic liver disease and the role of excess iron in chronic disease progression.