Evaluation of left ventricular mechanical dyssynchrony as determined by phase analysis of ECG-gated SPECT myocardial perfusion imaging in patients with left ventricular dysfunction and conduction disturbances

Background  Cardiac resynchronization therapy (CRT) is approved for the treatment of patients with advanced systolic heart failure and evidence of dyssynchrony on electrocardiograms. However, a significant percentage of patients do not demonstrate improvement with CRT. Echocardiographic techniques have been used for more accurate determination of dyssynchrony. Single photon emission computed tomography (SPECT) myocardial perfusion imaging has not previously been used to evaluate cardiac dyssynchrony. The objective of this study is to evaluate mechanical dyssynchrony as described by phase analysis of gated SPECT images in patients with left ventricular dysfunction, conduction delays, and ventricular paced rhythms. Methods and Results  A novel count-based method is used to extract regional systolic wall thickening amplitude and phase from gated SPECT images. Five indices describing the phase dispersion of the onset of mechanical contraction are determined: peak phase, phase SD, bandwidth, skewness, and kurtosis. These indices were determined in consecutive patients with left ventricular dysfunction (n=120), left bundle branch block (n=33), right bundle branch block (n=19), and ventricular paced rhythms (n=23) and were compared with normal control subjects (n=157). Phase SD, bandwidth, skewness, and kurtosis were significantly different between patients with left ventricular dysfunction, left bundle branch block, right bundle branch block, and ventricular paced rhythms and normal control subjects (all P<.001) Peak phase was significantly different between patients with right ventricular paced rhythms and normal control subjects (P=.001). Conclusions  A novel SPECT technique for describing left ventricular mechanical dyssyn-chrony has been developed and may prove useful in the evaluation of patients for CRT. This study was funded in part by a research grant from the Medtronic-Duke Strategic Alliance, of which Dr Borges-Neto is the primary investigator.     

Throwing induces substantial torsional adaptation within the midshaft humerus of male baseball players

Athletes participating in unilateral dominant sports are useful models for investigating skeletal responses to mechanical loading as they provide controlled evidence in the absence of completing a randomized controlled trial. Throwing athletes may be an additional model for this purpose as they overload their dominant upper extremity enabling the contralateral side to act as an internal control and load the bones of the upper extremity purely via the generation of internal (i.e. muscular) forces without superposition of externally applied loads (i.e. impact with an external object). The aim of this study was to investigate upper extremity bone adaptation in throwing athletes and explore factors that predict this adaptation. Two cohorts were recruited—male baseball players (throwers; n = 15) and matched controls (controls; n = 15). Each subject was assessed for shoulder range and strength, and upper extremity bone mass, structure and estimated strength. Throwers had substantially greater skeletal differences between their dominant and nondominant upper extremities than controls, indicating that throwing induces greater adaptation than induced by habitual loading of the dominant upper extremity. Bone adaptation in throwers was localized to the humerus, with the midshaft humerus in the dominant upper extremity of throwers having enhanced bone mass, structure and estimated strength. The largest effect was for estimated strength of the midshaft humerus which had 30% greater polar moment of inertia (I_P) in throwers and suggests adaptation to resist torsional loads. The skeletal effect of throwing at the midshaft humerus was influenced by playing position with pitchers and catchers displaying greater dominant-to-nondominant differences than fielders, and was predicted by years throwing and dominant-to-nondominant difference in upper arm lean cross-sectional area. The latter two variables explained 67% of the variance in dominant-to-nondominant differences in I_P. Collectively, these data indicate that throwing induces substantial adaptation within the midshaft humerus. Adaptation was primarily in the direction of torsion which is consistent with biomechanical and injury data suggesting throwing introduces high magnitude torsional forces. As the magnitude of adaptation in throwers was equivalent to that observed in athletes participating in other unilateral dominant sports, throwers represent an alternative model for investigating the skeletal effects of mechanical loading.     

Pharmacy customers’ views and experiences of using pharmacies which provide needle exchange services in Aberdeen and Glasgow, Scotland

Community pharmacists contribution to the management of drug problems is considerable. As the use of illicit drugs has increased, pharmacists have come under increasing pressure to offer services to problem drug users. However, there is concern among some pharmacists that offering such services may deter other customers. There is particular concern among some pharmacists about needle exchange services. Only 9.5% of Scottish pharmacies offer needle exchange services compared to 69% which are dispensing methadone (57% of which supervise methadone consumption). Qualitative interviews were used in a purposive sample of 10 pharmacies in Scotland. Eight customers were interviewed in each pharmacy to ascertain pharmacy customers’ views on these services. The majority of customers were supportive of these services. Customers were often unaware that the pharmacy they were interviewed in was offering services for people with drug problems. Pharmacy customers were more knowledgeable about, and more supportive, of needle exchange services than they were of methadone. This was because they believed needle exchange services helped to reduce the amount of discarded needles in public places. Pharmacy customers also recognised that needle exchange helped reduce the spread of disease. These findings should be used to encourage more pharmacists to offer needle exchange services.     

Multiple pilocytic astrocytomas of the cerebellum in a 17-year-old patient with neurofibromatosis type I

Objective Approximately 10% of patients with neurofibromatosis I (NFI) patients will have central nervous system (CNS) tumors. The most common of these are hypothalamic–optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. While isolated pilocytic astrocytomas in NFI are well described, the appearance of multiple pilocytic astrocytomas in an individual patient is less common. The most frequent combination in NFI patients with more than one pilocytic astrocytoma is optic tract/hypothalamic and brainstem. Other combinations are exceedingly rare; multiple pilocytic astrocytomas have only been reported once in the cerebral hemispheres in a patient with NFI. This report presents the first documented case, to our knowledge, of multiple pilocytic astrocytomas in the cerebellum of a patient with NF1. Methods Case report. Conclusion The finding of multiple cerebellar pilocytic astrocytomas in a patient with NF1 is important because it expands the spectrum of presentations for patients with NF1 and also highlights specific diagnostic and therapeutic challenges faced by the treating physicians. The genetic and molecular basis of NF1 is reviewed. Strategies of diagnosis and treatment outlined here are relevant to both patients with NF1 and all patients with multiple posterior fossa tumors.