Relation of QT interval and QT dispersion to echocardiographic left ventricular hypertrophy and geometric pattern in hypertensive patients. The LIFE study. The Losartan Intervention For Endpoint Reduction

OBJECTIVE: In hypertensive patients, left ventricular hypertrophy (LVH) predicts increased mortality, in part due to an increased incidence of sudden death. Repolarization-related arrhythmogenesis may be an important mechanism of sudden death in hypertensive patients with LVH. Increased QT interval and QT dispersion are electrocardiographic (ECG) measures of ventricular repolarization, and also risk markers for ventricular tachyarrhythmias. We assessed the relation of QT intervals and QT dispersion to echocardiographically determined left ventricular (LV) mass and geometry in a large population of hypertensive patients with ECG evidence of LVH. METHODS: QT intervals and QT dispersion were determined from baseline 12-lead ECGs in 577 (57% male; mean age 65 +/- 7 years) participants in the LIFE study. LV mass index (LVMI) and geometric pattern were determined by echocardiography and QT interval duration and QT dispersion were assessed in relation to gender-specific LVMI quartiles. RESULTS: In both genders, increasing LVMI was associated with longer rate-adjusted QT intervals. QT dispersion measures showed a weaker association with LVMI quartiles. Both concentric and eccentric LVH were associated with increased QT interval duration and QT dispersion. These relations remained significant after controlling for relevant clinical variables. CONCLUSIONS: In hypertensive patients with ECG evidence of LVH, increased LVMI and LVH are associated with a prolonged QT interval and increased QT dispersion. These findings suggest that an increased vulnerability to repolarization-related ventricular arrhythmias might in part explain the increased risk of sudden death in hypertensive patients with increased LV mass.     

Quality of life following DBS in the caudal zona incerta in patients with essential tremor

Background  

Essential tremor (ET) is the most common movement disorder and often affects the quality of life. There are only a few studies evaluating the quality of life after deep brain stimulation (DBS).     

Humeral head resurfacing in central bone defects: in vitro stability of different implants with increasing defect size

We examined the rotary motions of two distinct cementless surface replacement arthroplasties of the shoulder that were implanted on humeri with central spherical bone defects of 8%, 17%, and 37% of the head volume (n = 5 each). Rotary motions were measured under a cyclic torque application and translated into relative micromotions. Implant A with a perforated central crown had micromotions < 150 μm in all bony defects and during all simulated shoulder activities. Implant B with a central tapered tri-fin pin had no micromotions > 150 μm in defects of 0% and 8% during a strenuous activity like lifting 10 kg, but did exhibit micromotion > 150 μm in 40% of the experiments in defects of 17% and 37%, which could impair bony ingrowth. Implant B displayed a significant increase in micromotions for defects of 8% and 17% (p < 0.05). Our results suggest that implant A could be used without risk in spherical head defects up to 37% of volume, even in strenuous shoulder activities immediately after its implantation. Implant B, however, is recommended in spherical defects starting from 8% and only during light shoulder activities until bony integration of the implant has occurred.     

Deep Brain Stimulation of Caudal Zona Incerta for Parkinson's Disease: One-Year Follow-Up and Electric Field Simulations

ObjectiveTo evaluate the effects of bilateral caudal zona incerta (cZi) deep brain stimulation (DBS) for Parkinson's disease (PD) one year after surgery and to create anatomical improvement maps based on patient-specific simulation of the electric field.Materials and MethodsWe report the one-year results of bilateral cZi-DBS in 15 patients with PD. Patients were evaluated on/off medication and stimulation using the Unified Parkinson's Disease Rating Scale (UPDRS). Main outcomes were changes in motor symptoms (UPDRS-III) and quality of life according to Parkinson's Disease Questionnaire-39 (PDQ-39). Secondary outcomes included efficacy profile according to sub-items of UPDRS-III and simulation of the electric field distribution around the DBS lead using the finite element method. Simulations from all patients were transformed to one common magnetic resonance imaging template space for the creation of improvement maps and anatomical evaluation.ResultsMedian UPDRS-III score off medication improved from 40 at baseline to 21 on stimulation at one-year follow-up (48%, p < 0.0005). PDQ-39 summary index did not change, but the subdomain activities of daily living (ADL) and stigma improved (25%, p < 0.03 and 75%, p < 0.01), whereas communication worsened (p < 0.03). For UPDRS-III sub-items, stimulation alone reduced median tremor score by 9 points, akinesia by 3, and rigidity by 2 points at one-year follow-up in comparison to baseline (90%, 25%, and 29%, respectively, p < 0.01). Visual analysis of the anatomical improvement maps based on simulated electrical fields showed no evident relation with the degree of symptom improvement and neither did statistical analysis show any significant correlation.ConclusionsBilateral cZi-DBS alleviates motor symptoms, especially tremor, and improves ADL and stigma in PD patients one year after surgery. Improvement maps may be a useful tool for visualizing the spread of the electric field. However, there was no clear-cut relation between anatomical location of the electric field and the degree of symptom relief.     

Impact of blood flow on diffusion coefficients of the human kidney: A time‐resolved ECG‐triggered diffusion‐tensor imaging (DTI) study at 3T

Purpose:

To evaluate the impact of renal blood flow on apparent diffusion coefficients (ADC) and fractional anisotropy (FA) using time‐resolved electrocardiogram (ECG)‐triggered diffusion‐tensor imaging (DTI) of the human kidneys.

Materials and Methods:

DTI was performed in eight healthy volunteers (mean age 29.1 ± 3.2) using a single slice coronal echoplanar imaging (EPI) sequence (3 b‐values: 0, 50, and 300 s/mm²) at the timepoint of minimum (20 msec after R wave) and maximum renal blood flow (200 msec after R wave) at 3T. Following 2D motion correction, region of interest (ROI)‐based analysis of cortical and medullary ADC‐ and FA‐values was performed.

Results:

ADC‐values of the renal cortex at maximum blood flow (2.6 ± 0.19 × 10^?3 mm²/s) were significantly higher than at minimum blood flow (2.2 ± 0.11 × 10^?3 mm²/s) (P < 0.001), while medullary ADC‐values did not differ significantly (maximum blood flow: 2.2 ± 0.18 × 10^?3 mm²/s; minimum blood flow: 2.15 ± 0.14 × 10^?3 mm²/s). FA‐values of the renal medulla were significantly greater at maximal blood (0.53 ± 0.05) than at minimal blood flow (0.47 ± 0.05) (P < 0.01). In contrast, cortical FA‐values were comparable at different timepoints of the cardiac cycle.

Conclusion:

ADC‐values in the renal cortex as well as FA‐values in the renal medulla are influenced by renal blood flow. This impact has to be considered when interpreting renal ADC‐ and FA‐values. J. Magn. Reson. Imaging 2013;37:233–236. © 2012 Wiley Periodicals, Inc.

     

Mapping complex tissue architecture with diffusion spectrum magnetic resonance imaging.

Methods are presented to map complex fiber architectures in tissues by imaging the 3D spectra of tissue water diffusion with MR. First, theoretical considerations show why and under what conditions diffusion contrast is positive. Using this result, spin displacement spectra that are conventionally phase-encoded can be accurately reconstructed by a Fourier transform of the measured signal's modulus. Second, studies of in vitro and in vivo samples demonstrate correspondence between the orientational maxima of the diffusion spectrum and those of the fiber orientation density at each location. In specimens with complex muscular tissue, such as the tongue, diffusion spectrum images show characteristic local heterogeneities of fiber architectures, including angular dispersion and intersection. Cerebral diffusion spectra acquired in normal human subjects resolve known white matter tracts and tract intersections. Finally, the relation between the presented model-free imaging technique and other available diffusion MRI schemes is discussed.     

The menisco-femoral ligaments

The menisco-femoral ligaments were studied in 60 knees from 30 dissecting room cadavers. The anterior horns of the menisci were attached to the intercondylar area of the femur by discrete antero-medial or antero-lateral menisco-femoral ligaments, separate from the anterior cruciate ligament, in 15% of knees for each meniscus, more frequently than previously appreciated; these anterior horn ligaments may exacerbate a meniscal tear. The posterior horn of the lateral meniscus was connected with the intercondylar area of the femur in 100% of knees. In 93% of knees a ligament ran behind the posterior cruciate ligament while in 33% of knees a ligament ran in front of the posterior eruciate ligament. We propose renaming these the pre-cruciate postero-lateral menisco-femoral ligament and post-cruciate postero-lateral menisco-femoral ligament, respectively, to avoid confusion with the ligaments of the anterior horns. The menisco-femoral ligaments may function in controlling movement of the menisci, especially during rotation of the knee. The posterior horn of the medial meniscus has no direct femoral attachment and this may be a factor in the increased risk of injury to this meniscus. © 1995 WiIey-Liss, Inc.     

Airway Injuries after One-lung Ventilation: A Comparison between Double-lumen Tube and Endobronchial Blocker: A Randomized, Prospective, Controlled Trial

Background: Vocal cord injuries, postoperative hoarseness, and sore throat are common complications after general anesthesia. One-lung ventilation can be achieved via two techniques: double-lumen endotracheal tube or endobronchial blocker such as the Arndt blocker. The current study was designed to assess the impact of these techniques for one-lung ventilation on the incidence and severity of postoperative hoarseness, vocal cord lesions, and sore throat.

Methods: In this prospective trial, 60 patients were randomly assigned to two groups. One-lung ventilation was achieved with either an endobronchial blocker (blocker group) or a double-lumen-tube (double-lumen group). Postoperative hoarseness and sore throat were assessed at 24, 48, and 72 h after surgery. Bronchial injuries and vocal cord lesions were examined by bronchoscopy immediately after surgery.

Results: In 56 included patients, postoperative hoarseness occurred significantly more frequently in the double-lumen group compared with the blocker group: 44% versus 17%, respectively (P = 0.046). Similar findings were observed for vocal cord lesions: 44% versus 17%, respectively (P = 0.046). The incidence of bronchial injuries was comparable between groups (P = 0.540). Cumulative number of days with hoarseness and sore throat were significantly increased in the double-lumen group compared with the blocker group (P < 0.01). No major complications such as bronchial ruptures were observed.