Aspergillus endocarditis in chronic granulomatous disease

We report the first case, to our knowledge, of Aspergillus endocarditis in chronic granulomatous disease in a patient who also had an atrial septal defect. A diagnosis was made on culture of the organism from the mass despite extensive prior investigation. The presence of distinctive skin lesions as a diagnostic clue of fungaemia is highlighted. Possible advances in diagnosis by detection of fungal cell wall components and in prophylaxis by use of itraconazole are referred to. We conclude that fungal endocarditis should be considered in this condition, especially in the presence of a structural heart defect.     

Regional myocardial dysfunction: evaluation of patients with prior myocardial infarction with fast CT

A prototype ultrafast cine computed tomographic (CT) scanner, designed specifically for cardiac imaging, was used to evaluate a preliminary series of patients with prior myocardial infarction (n = 21) and a control group without coronary artery disease (n = 5). Multilevel 50-msec CT scan exposures were obtained during peripheral intravenous bolus injections of contrast medium. A comparison was made between cine-CT scans and standard left ventriculographic images in assessing segmental left ventricular motion. Results indicate that cine CT, performed at sufficiently rapid speeds (20 scans per second) to allow useful analysis of regional ventricular wall motion, can provide adequate image quality. Analysis of 110 segments revealed a good correlation (90.9%) between the two techniques in characterizing normal from abnormal regional wall motion. Cine CT, based on this initial study, demonstrates considerable potential for evaluating not only cardiac chamber dimensions but also segmental wall dynamics.     

Ferromagnetic materials in patients: detection before MR imaging

A number of surgical clips and other metallic materials embedded within patients have ferromagnetic properties that present a potential hazard when in the strong fields associated with magnetic resonance imaging. Several types of magnetometers and metal detectors were investigated as possible pre-imaging screening devices. The sensitivities and costs of these devices are given.     

Overnight changes of chemoreflex control in obstructive sleep apnoea patients

We hypothesized that the numerous episodes of hypoxia, hypercapnia and arousal experienced by obstructive sleep apnoea (OSA) patients induce overnight changes in respiratory chemoreflexes. A modification of the Read rebreathing technique assessed chemoreflex characteristics in the evening and the morning of patients undergoing diagnostic assessment for OSA in a clinical sleep laboratory. Two groups were studied: those with apnoea-hypopnoea indices (AHI) greater than 30 composed the OSA group (n = 12), and those with AHI indices less than 10 composed the non-OSA group (n = 12). There was a significant (approximately 30%) overnight increase in chemoreflex sensitivities, without changes in thresholds, in the OSA group. In the non-OSA group there was a significant overnight reduction in chemoreflex thresholds (approximately 5%), without changes in sensitivities. We suggest that these changes affect the stability of the chemoreflex control system in opposite ways as the night proceeds: destabilizing breathing for patients in the OSA group, and stabilising breathing for patients in the non-OSA group.     

Impact of nocturnal hemodialysis on the variability of heart rate and duration of hypoxemia during sleep

BACKGROUND: Nocturnal hemodialysis (NHD) alleviates uremia-related sleep apnea, a condition characterized by increased sympathetic activity and diminished heart rate (HR) variability. We tested the hypothesis that NHD reduces both hypoxemia and sympathetic neural contributions to HR variability during sleep. METHODS: Episodes of apnea and hypopnea and the duration of nocturnal hypoxemia during sleep were determined in 9 end-stage renal disease (ESRD) patients (age: 44 +/- 2) (mean +/- SEM) before and after conversion from conventional hemodialysis (CHD) to NHD, and in 10 control subjects (age: 45 +/- 3) with normal renal function and without sleep apnea. Low frequency (LF) (0.05-0.15 Hz) and high frequency (HF) (0.15-0.5 Hz) HR spectral power during stage 2 sleep was calculated (Fast Fourier transformation). Patients were studied 4 times (1 day before and on the night after their CHD session) and 6-15 months after conversion to NHD, while receiving NHD and on a non-dialysis night. RESULTS: NHD decreased the frequency of apnea and hypopnea (from 29.7 +/- 9.3 to 8.2 +/- 2.0 episodes per hour, P= 0.02), and duration of nocturnal hypoxemia (from 13.9 +/- 5.2 to 2.6 +/- 1.9% of total sleep time, P= 0.02). As CHD recipients, ESRD patients had faster nocturnal heart rates (79 +/- 2 vs. 58 +/- 1 min-1, P= 0.03) and lower HF (vagal) (78 +/- 27 vs. 6726 +/- 4556 ms2, P= 0.001) spectral power than control subjects. After conversion to NHD, HR fell (from 79 +/- 2 to 66 +/- 1 min-1, P= 0.03) and HF power increased (from 78 +/- 27 to 637 +/- 139 ms2, P= 0.001). The HF/HF+LF ratio, an index of vagal HR modulation, was lower during CHD (0.16 +/- 0.03 vs. 0.42 +/- 0.05 in control subjects, P < 0.05) and increased (to 0.45 +/- 0.05, P < 0.001) after conversion to NHD. The LF/HF ratio, a representation of sympathetic HR modulation, which was significantly higher during CHD than in control subjects (2.77 +/- 0.82 vs. 0.71 +/- 0.11, P < 0.05), was also normalized by NHD (0.74 +/- 0.12, P < 0.05, compared with CHD). CONCLUSION: Higher heart rates and impaired vagal and augmented sympathetic HR modulation during sleep in ESRD patients are normalized by NHD. Potential mechanisms for these observations include attenuation of surges in sympathetic outflow elicited by apnea and hypoxia during sleep, normalization of nocturnal breathing patterns that influence HRV, and removal, by increased dialysis, of a sympatho-excitatory stimulus of renal origin.