Chronic neutrophilic leukaemia with enlarged lymph nodes and lysozyme deficiency

A further case of chronic neutrophilic leukaemia is reported and compared to fourteen previously reported cases. The presence of enlarged lymph nodes as the first clinical sign and the existence of a relative lysozyme deficiency of the granulocytes were striking features.     

Behavior of a Respiratory Driven Pacemaker and Direct Respiratory Measurements

In 10 patients with a mean age of 76 +/- 8 years, a rate responsive pacemaker (Meta-MV, Telectronics) was implanted in the left pectoral site. An exercise test was performed in SSI ("adaptive") mode, allowing the device to measure the changes in thoracic impedance. The "slope number" at maximal exercise was chosen to program the pacemaker for a second exercise test in rate responsive mode. Direct measurements of respiratory rate and minute volume were correlated with the pacing rate. After 1 minute of exercise, pacing rate increased by 6% and it decreased smoothly after maximal exercise. The programmed maximal rate was reached at the maximum exercise level in six patients. During 24-hour Holter recording, the mean maximal pacing rate was 103 +/- 18 beats/min. For individual patients, a good correlation of pacing rate with respiratory rate (r = 0.757), oxygen consumption (r = 0.731), and minute volume (r = 0.800) was observed. The data from the entire group showed a highly significant correlation of changes in pacing rate and in respiratory parameters for different levels of exercise and recovery. In a subgroup of five patients, the slope numbers at maximal exercise were reproducible after 10 months. It was concluded that minute volume and its changes were recognized in a reliable way by the Meta-MV pacemaker.     

Correlation of the Heart Rate-Minute Ventilation Relationship with Clinical Data: Relevance to Rate-Adaptive Pacing

The heart rate (HR)-minute ventilation (VE) relationship has been shown to be nonlinear and can be expressed as two distinct straight lines. This study is to assess the correlation of the initial HR-VE slope to clinical parameters. Maximum treadmill exercise tests were performed in 100 healthy volunteers (age 19–77 years) using a ramp protocol in which work-rate increases linearly with exercise. Breath-by-breath VO₂, VCO₂, and VE were measured, and HR and RP were monitored throughout the exercise. The HR-VE curve demonstrated nonlinearity with a breakpoint determined by a change point analysis. This breakpoint was significantly higher than that of the anaerobic threshold. The VEat the HB-VE breakpoint was 56.4 ± 19.4 and VE at the VE-VO₂ and VCO₂-VO₂ breakpoints were 48.0 ± 18.3 (P < 0.0001) arid 40.1 ± 16.5 (P < 0.0001). respectively. TheHR at this HR-VE breakpoint was 77.7 ± 12.9% of the HR range. The first slope. Si (1.76 ± 0.64) was steeper than the second slope, S2 (0.66 ± 0.39). Although there was a gender difference for S1, the best clinical predictor on a stepwise multiple regression analysis was body surface area (BSA) which explained 47% of the variance. It was concluded that nonlinearity of the HR-VE curve can be expressed as two straight lines. The breakpoint is beyond the anaerobic threshold and can be estimated to be approximately 75% of the maximal predicted HR. RSA is the only clinical parameter that significantly predicts the initial slope of the HR-VE curve. This can be of great importance in the programming of rate-adaptive pacemakers using a VE.     

Combined immunophenotyping and in situ hybridization (FICTION): a rapid method to study cell lineage involvement in myelodysplastic syndromes

Summary. We present a study in which we used a recently described method combining fluorescence in situ hybridization (FISH) and immunophenotyping, i.e. FICTION, to assess the involvement of different cell lineages in myelodysplastic syndrome (MDS) with monosomy 7 (–7), trisomy 8 (+8) or loss of Y chromosome (–Y). Blood or marrow smears or cytocentrifuge preparations were stained both by antibodies to granulocytes (CD₁₅), monocytes (CD₁₄), T lymphocytes (CD₃), B lymphocytes (CD₂o) and by probes specific for chromosomes 7, 8 or Y. Of nine cases of MDS with –7, four with +8 and two with – Y studied, none showed lymphocytic involvement by the chromosome abnormality. In contrast, -7,-1-8 and – Y were found in granulocytes and monocytes in all patients studied, but they involved a variable proportion of those cells. The partial involvement by –7 and +8 seen in some cases suggests that myelopoi'esis was only partially clonal in those cases, or that the chromosome abnormality was a secondary event in the MDS process. FICTION therefore appears to be a simple and easily reproducible method that can be used for the assessment of lineage involvement in MDS and other haematological malignancies.     

Implantation of a Dual Chamber Pacemaker in a Patient with Persistent Left Superior Vena Cava

A patient underwent dual chamber pacemaker implantation by puncture of the left subclavian vein. During the procedure we observed persistence of the left superior vena cava. A "J-shaped" atrial lead was used for ventricular pacing with excellent long-term results. This technique can be a valuable alternative when confronted with the problem of persistent left superior vena cava during pacemaker implantation.     

QT-Related Rate-Responsive Pacing During Acute Myocardial Infarction

We studied the findings in a patient who had a TX 915 pacemaker and who was suffering from an acute inferior myocardial infarction. On admission, we observed pacing at the upper rate limit due to excessive adrenergic tone. Shortly thereafter a strong vagal reaction occurred, and the pacing rate fell back to the lower rate limit. This condition was improved with atropine. Conclusions: (1) In the described condition the TX pacemaker behaved in a very "physiological" fashion; (2) Sudden strong cholinergic activity lengthened the QT interval; (3) Programming of a steep slope must be avoided in coronary artery disease; (4) Stimulus-T-wave intervals at maximal adrenergic and cholinergic stimulation should be taken into account when programming the slope and the T-wave sensing window.     

Computer Aided Development of Antiarrhythmic Agents with Class IIIa Properties

Antiarrhythmic Agents. Most antiarrhythmic agents were discovered accidentally. In the last decade, the understanding of the mechanisms of action of agents with electrophysioiogic activity has progressed greatly. As a result, it was possible to compute, before the CAST trial, that the agents selected for the trial would not be effective against tachycardias and that the drugs would be unsafe. Extension of these computations to existing Class 1 agents indicated that they were all poor suppressors of ventricular tachycardia. Furthermore, a Class I agent with an optimal electrophysioiogic profile still computes to be a two-edged sword, possessing both antiarrhythmic and p roar rhythmic properties. Fortunately, it is possible to conceive of drug profiles that would be purer antiarrhythmic agents. For example, a drug that only upon the development of a tachycardia lengthens action potential duration in a use-dependent manner until the refractory period exceeds the tachycardia cycle length will render continuation of the tachycardia impossible. Recognition of chemicals that have Class III, properties with the appropriate kinetics is a challenging task. However, today's microprocessors have become powerful enough to characterize the Class HI kinetics. A system that fully automatically screens for effective antiarrhythmic agents is described. It is expected that chemicals selected for optimal basic electro-physiologic properties will yield safer and more effective antiarrhythmic agents.     

Transvenous Cryothermal Catheter Ablation of a Right Anteroseptal Accessory Pathway

In patients with Wolff-Parkinson-White syndrome, right anteroseptal accessory pathways are uncommon and run from the atrium to the ventricle in close anatomic proximity to the normal AV conduction system. Radiofrequency catheter ablation is the first-line therapy for elimination of these accessory pathways. Although the initial success rate is high, there is a potential risk of inadvertent development of complete heart block, and the recurrence rate is relatively high. The capability of cryothermal energy to create reversible lesions (ice mapping) at less severe temperatures provides a potential benefit in ablation of pathways located in a complex anatomic area, such as the mid-septum and anteroseptum.     

Intravenous Immunoglobulin: An Update on the Clinical Use and Mechanisms of Action

Initially used as a replacement therapy for immunodeficiency diseases, intravenous immunoglobulin (IVIg) is now widely used for a number of autoimmune and inflammatory diseases. Considerable progress has been made in understanding the mechanisms by which IVIg exerts immunomodulatory effects in autoimmune and inflammatory disorders. The mechanisms of action of IVIg are complex, involving modulation of expression and function of Fc receptors, interference with activation of complement and the cytokine network and of idiotype network, regulation of cell growth, and effects on the activation, differentiation, and effector functions of dendritic cells, and T and B cells.