Lack of Physiological Adaptation of the Atrioventricular Interval to Heart Rate in Patients Chronically Paced in the AAIR Mode

Seventeen consecutive patients, aged 56 +/- 12, were chronically paced in the AAIR mode for a symptomatic sinus node disease with atrial chronotropic incompetence defined by a peak exercise heart rate (HR) less than 75% of the maximal predicted heart rate (MPHR) mean = 65 +/- 10%). Sensors used were activity sensing (n = 7), minute ventilation (n = 6), or respiratory rate (n = 4). Basic pacing rate was programmed at 71 +/- 5 beats/min and the maximal sensor rate at approximately 85% MPHR (143 +/- 10); other sensor parameters were programmed individually. Six months after implant, two standardized and symptom limited exercise tests were performed in random order, AAI and AAIR modes, respectively. AAIR pacing significantly improved peak exercise HR (139 +/- 14 vs 112 +/- 30 beats/min; P less than 0.01), maximal sustained workload (132 +/- 42 vs 110 +/- 38 watts; P less than 0.02), and total exercise duration (724 +/- 299 vs 594 +/- 245 sec; p less than 0.02) compared to the AAI mode. In all 17 patients, HR was continuously sensor driven in the AAIR mode, making it possible to precisely study the adaptation of the stimulus-R interval and of the stimulus-R:RR ratio during exercise. Six patients normally adapted with a progressive shortening. Six others did not adapt at all without any variation of interval. Five patients paradoxically increased their stimulus-R interval (286 +/- 10 msec at peak E vs 220 +/- 19 msec at rest) and their stimulus-R:RR ratio (67 +/- 20% vs 29 +/- 4%), producing P waves occurring immediately after, or even within the R wave of the preceding cycle; two patients complained of severe exercise related symptoms corresponding to the so-called "AAIR pacemaker syndrome." The principal factors involved in the nonadaptation of AV interval to HR were related to the patient (organic heart disease, with the particular problem of the denervated heart; the bradytachy syndrome; and the use of drugs, especially beta blockers and Class I antiarrhythmic drugs) or to the pacemaker ("overstimulation" phenomenon). These observations constitute an additional argument for wider indications of implanting DDDR units in these patients.     

Platelet alpha2 adrenoceptors in Parkinson''s disease: decreased number in untreated patients and recovery after treatment

[3H]-yohimbine binding sites were quantified in platelets from Parkinsonians with no clinical signs of dysautonomia. Never-treated Parkinsonians had a lower specific binding than control subjects. This alteration was associated with decreased epinephrine-induced platelet aggregation. Treatment with dopaminergic agents induced a significant increment of [3H]-yohimbine binding sites. These results show that Parkinson's disease is associated with a reduced number of peripheral alpha 2 adrenoceptors and that dopaminergic agents induce partial recovery.     

Algorithms for sleep–wake identification using actigraphy: a comparative study and new results

The aim of this study was to investigate two new scoring algorithms employing artificial neural networks and decision trees for distinguishing sleep and wake states in infants using actigraphy and to validate and compare the performance of the proposed algorithms with known actigraphy scoring algorithms. The study employed previously recorded longitudinal physiological infant data set from the Collaborative Home Infant Monitoring Evaluation (CHIME) study conducted between 1994 and 1998 [ http://dccwww.bumc.bu.edu/ChimeNisp/Main_Chime.asp ; Sleep 26 (1997) 553 ] at five clinical sites around the USA. The original CHIME data set contains recordings of 1079 infants <1 year old. In our study, we used the overnight polysomnography scored data and ankle actimeter (Alice 3) raw data for 354 infants from this data set. The participants were heterogeneous and grouped into four categories: healthy term, preterm, siblings of SIDS and infants with apparent life‐threatening events (apnea of infancy). The selection of the most discriminant actigraphy features was carried out using Fisher’s discriminant analysis. Approximately 80% of all the epochs were used to train the artificial neural network and decision tree models. The models were then validated on the remaining 20% of the epochs. The use of artificial neural networks and decision trees was able to capture potentially nonlinear classification characteristics, when compared to the previously reported linear combination methods and hence showed improved performance. The quality of sleep–wake scoring was further improved by including more wake epochs in the training phase and by employing rescoring rules to remove artifacts. The large size of the database (approximately 337 000 epochs for 354 patients) provided a solid basis for determining the efficacy of actigraphy in sleep scoring. The study also suggested that artificial neural networks and decision trees could be much more routinely utilized in the context of clinical sleep search.     

Trainee impact on advanced diagnostic bronchoscopy: An analysis of 607 consecutive procedures in an interventional pulmonary practice

Background and objective: Complications during advanced diagnostic bronchoscopy are rare and include: pneumothorax, bleeding, mediastinitis and lymphadenitis. Increased complications have been demonstrated in patients undergoing routine bronchoscopy procedures performed by trainees. This study aimed to determine the impact of trainees during advanced diagnostic bronchoscopy on procedure time, sedation use and complications. Methods: A retrospective review of a quality improvement database including consecutive pulmonary procedures performed by an interventional pulmonologist (D.R.S.) at the University of Calgary, from 1 July 2007 to 1 April 2011. Results: Six hundred seven (55.2%) of the 1100 procedures involved an advanced diagnostic procedure defined as: endobronchial ultrasound‐guided transbronchial needle aspiration (EBUS‐TBNA), electromagnetic navigation bronchoscopy (ENB) and/or peripheral EBUS. A trainee participated in 512 (84.3%) procedures. A complication occurred in 25 patients (4.1%), with a trend towards increased complication rates in the trainee group (4.7% vs 1.1%, difference 3.6%, P = 0.076). Significant differences were seen when a trainee participated versus when no trainee participated for procedure length (58.32 min vs 37.69 min, difference 20.63 min (95% confidence interval: 19.07–22.19), P = 0.001) and for the dose of propofol (178.3 mg vs 137.1 mg, difference 41.2 mg (95% confidence interval: 19.81–63.38), P = 0.002). Conclusions: In an academic interventional pulmonology practice utilizing the apprenticeship model, trainee participation in advanced diagnostic bronchoscopy increased procedure time, increased the amount of sedation used and resulted in a trend to increased complications. Attempts to modify trainee procedural training to reduce the burden of procedural learning for patients are warranted.     

Heart Transplantation for Corrected Transposition of the Great Vessels

Orthotopic heart transplantation was performed in a patient with corrected transposition of the great vessels. Technical modifications were necessary to be able to transplant a normal heart in this patient. The surgical technique is illustrated.     

Hepatic GVHD after HLA-haploidentical bone marrow transplantation in children with severe combined immunodeficiency: the effect of ursodeoxycholic acid

We describe two children with a severe combined immune deficiency (SCID) with B cells. Following a T-cell-depleted haploidentical bone marrow transplantation (BMT), they both developed a chronic graft-versus-host disease (GVHD) of the skin and a severe persisting hyperbilirubinaemia and elevated liver enzymes. The diagnosis of a vanishing bile duct syndrome was confirmed by liver biopsies. Because corticosteroids and cyclosporin A induced only a partial response, ursodeoxycholic acid (UDCA) was added to their treatment schedule. Serum bilirubin and liver enzymes returned to normal within months. A control liver biopsy showed normal and proliferating bile ducts without cholestatic damage. We conclude that UDCA was well tolerated and may be of value as an additional treatment for hepatic GVHD in SCID.     

Mastication after surgical reconstruction of the mandibular residual ridge

A group of thirty-one female denture patients who underwent surgical reconstruction of their deficient residual ridges with ridge extension and skin graft or ridge augmentation with bone graft were evaluated with regard to their masticatory function before surgery, then at 8 months and 12 months post-operative with their new dentures. Two objectives tests of masticatory efficiency were used. The masticatory efficiency index (MEI), based on the size of chewed almond particles, determined the potential capacity of patients to masticate while the masticatory performance (MP) based on the time required to masticate food before swallowing assessed the individual ability of each patient to chew food. A subjective index of difficulty (SD) provided information on the patient's own assessment of chewing difficulty of certain foods selected for their hard texture. The evolution of each index and their interrelationship were statistically evaluated. It was shown that the masticatory performance (MP) and the subjective index of difficulty (SD) both improved significantly during the rehabilitation period and even more rapidly than the masticatory efficiency index (MEI). The discrepancy between the objective and the subjective tests and the overestimation from the patients indicate that the real benefit of the rehabilitation is not limited to improved chewing, but also to an acquired self-confidence in mastication.     

Destruxin analogs: variations of the α-hydroxy acid side chain

This work describes the synthesis of three destruxin E cyclodepsipeptidic analogs. These compounds have an identical amino acid sequence but differ by the nature of the hydroxy acid residue which is 2-hydroxy-3-phenylpropionic (Hpp), 2-hydroxy-5-trimethylsilyl-4-pentynoic (Hpy-TMS) and 2-hydroxy-4-pentynoic (Hpy) acid, respectively. The insecticidal properties on the Galleria mellonella larvae (paralysis and lethal effect) of these analogs are presented in comparison with the natural destruxin E. All these compounds have toxic effects, the most potent being Hpy that induces the same effect as destruxin E.