Multimodality Neuromonitoring for Neurocardiology

Neurophysiologic monitoring, including quantitative EEG, transcranial Doppler (TCD) ultrasound and transcranial near-infrared spectroscopy (NIRS), can be of diagnostic value in neurocardiology—the study of dysfunctional brain-heart relationships. A new multivariate EEG technique bispectral analysis, enables the cardiologist to objectively and precisely document transient episodes of syncope and seizure. TCD permits precise determination of the nature and extent of cerebral hemodynamic irregularities, while NIRS detects frontal lobe imbalance in the delivery and consumption of oxygen. These powerful new neurophysiologic tools, coupled with traditional systemic hemodynamic and electrocardiographic measures, will undoubtedly improve the diagnostic yield in the complex determination of the causes of syncope and cardiac-based confusional states.     

THE EFFECT OF ACUTE RADIATION INJURY ON THE PERMEABILITY AND ULTRASTRUCTURE OF INTRACEREBRAL CAPILLARIES

A study was made on the vascular permeability alteration produced in the rat brain 2 to 9 days after a single application of 30 krad of X-rays. The permeability was assessed by fluorescence and electron microscopy following intravenous injection of Evans blue-albumin (EBA) and horseradish peroxidase (HP). Both tracers penetrated vascular walls and spread extensively outside the vessels in the irradiated regions. The HP penetrated between separated endothelial cells or through gaps formed by necrotic endothelial cells. The vascular basement membranes and the perivascular astrocytes did not prevent the further diffusion of HP. Lesions of the vascular endothelium are considered to be of crucial importance for the extravasation of proteins in acute radionecrosis of the brain.     

Optical Mapping Technique Applied to Biventricular Pacing:

GARRIGUE, S., et al .: Optical Mapping Technique Applied to Biventricular Pacing: Potential Mechanisms of Ventricular Arrhythmias Occurrence. Although it has been suggested that multisite ventricular pacing alleviates heart failure by restoring ventricular electrical synchronization, the respective roles of voltage output, interventricular delay, and pacing sites in the development of ventricular arrhythmias occurrence have not been studied during biventricular pacing or LV pacing. Voltage-sensitive dye was used in eight ischemic Langerdorff-perfused guinea pig hearts to measure ventricular activation times and examine conduction patterns during multisite pacing from three RV and four LV sites. The hearts were stained with di-4-ANEPPS and mapped with a   16 × 16   photodiode array at a resolution of 625 μm per diode. Isochronal maps of RV and LV activation were plotted. Ischemia was produced by gradually halving the perfusion output over 5 minutes. Pacing the RV apex and the base of the LV anterior wall was associated with the most homogeneous and rapid activation pattern (   28 ± 9   vs   41 ± 12   ms with the other configurations, P < 0.01), and no inducible arrhythmia. In six hearts, ventricular tachycardia could be induced when pacing from the right and left free walls with 20 ms of interventricular delay, at six times the pacing threshold output. In four hearts, simultaneous RV and LV pacing at high voltage output induced ventricular fibrillation with complex three-dimensional propagation patterns, independently of the pacing sites. During biventricular pacing with ischemia, pacing at high voltage output with a long interventricular delay is likely to induce ventricular arrhythmias, particularly when left and right pacing results in a conduction pattern orthogonal to the ventricular myocardial fibers orientation. PACE 2003; 26[Pt. II]:197–205)     

Patch Migration: A Serious Late Complication of Thoracotomy Lead Systems

Thoracotomy patch leads used for implantable cardioverter defibrillators (ICDs) are generally safe and effective. We describe two patients in whom a late complication of patch lead migration occurred years after the original implants, causing a bronchopleural fistula in one and lingular lobe collapse in the other patient. We conclude that patch migration is a late but possible complication of extrapericardial ICD leads, and should be suspected in patients who present with hemoptysis, atypical pneumonia, or lung collapse after the initial ICD surgery.     

Determination of Repetitive Slow Pathway Conduction for Evaluation of the Efficacy of Radiofrequency Ablation in AVNRT

LUKAC, P., et al.: Determination of Repetitive Slow Pathway Conduction for Evaluation of the Efficacy of Radiofrequency Ablation in AVNRT. Aims: To determine whether the loss of repetitive slow pathway conduction identifies a successful radiofrequency ablation of atrioventricular nodal reentry tachycardia (AVNRT). Methods and results: Thirty nine consecutive patients undergoing ablation of AVNRT using the slow pathway approach were included. At baseline and after each radiofrequency application with an episode of junctional rhythm, repetitive slow pathway conduction was assessed as follows: Effective refractory period of the fast pathway was determined. The coupling interval of the first atrial extrastimulus (A2) was set at 30 ms below the effective refractory period of the fast pathway to ensure its conduction via the slow pathway. The second atrial extrastimulus (A3) was introduced at progressively longer coupling intervals starting from 200 ms until: (1) it propagated to the His bundle or (2) an anterogradely blocked AV nodal echo of A2 appeared before a conducted A3 depolarized the atrium in the His bundle electrogram. The response was termed repetitive slow pathway conduction if A3 was conducted with an   AH > 200 ms   . Application was considered successful if no AVNRT could be induced. Repetitive slow pathway conduction was present after 1 of 39 successful and after 34 of 40 ineffective applications   (P < 0.0001)   . Repetitive slow pathway conduction identified a successful application with 97% sensitivity, 86% specificity, 86% positive predictive value, and 97% negative predictive value. Conclusion: The presence of repetitive slow pathway conduction identifies an unsuccessful application with a clinically meaningful negative predictive value. (PACE 2003; 26[Pt. I]:827–835)     

Biventricular Shocking Leads Improve Defibrillation Efficacy

INTRODUCTION: A single lead active can configuration has been widely used in patients with life-threatening ventricular arrhythmias. Occasionally, however, such a defibrillation lead configuration may not achieve adequate defibrillation threshold (DFT). The purpose of this study was to determine whether addition of a left ventricular (LV) lead can improve defibrillation efficacy. METHODS AND RESULTS: Three transvenous defibrillation leads (8.3-French with a 5-cm long unipolar coil) were placed in the right ventricle (RV), LV, and superior vena cava (SVC), along with an active can (92 cm2) in the left subpectoral area. The DFT stored energy of seven combinations of these defibrillation leads were compared in a pig ventricular fibrillation model using a biphasic defibrillation waveform (125 microF, 6.5/3.5 msec). A biventricular leads active can configuration in which the RV and LV leads were of the same polarity reduced the DFT stored energy by approximately 35% when compared to a single RV lead active can configuration (9.6 +/- 3.0 J vs 15.0 +/- 7.2 J, respectively, P = 0.02). Moreover, adding a SVC lead further reduced the DFT energy (8.4 +/- 3.3 J). CONCLUSION: A biventricular leads active can configuration can significantly improve defibrillation efficacy as compared to a single lead active can configuration. In such a defibrillation lead configuration, the polarity of RV and LV leads should be the same.     

HEALTH-RELATED QUALITY OF LIFE IN OLDER PATIENTS WITH SCHIZOPHRENIA AND OTHER PSYCHOSES: RELATIONSHIPS AMONG PSYCHOSOCIAL AND PSYCHIATRIC FACTORS

Objective. Few multivariate studies relating psychosocial factors to symptoms of psychosis among older patients exist. We assessed environmental stressors, satisfaction with emotional support, coping responses and psychiatric symptoms, and sought to relate these factors to quality of well-being among older patients with schizophrenia and other psychoses. Method. Subjects were 70 psychosis patients with a mean age of 58. Predictors included measures of stressors (number of negative life events), satisfaction with emotional support, coping responses, positive and negative symptoms, depressive symptoms, social adjustment and a general quality of well-being (QWB) score. Results. A conceptual model was tested and modified using path analytic techniques. Preliminary analyses suggested that psychosocial environment (life events, coping and emotional support) was primarily a product of psychiatric symptoms. Therefore, psychiatric symptoms preceded psychosocial environment variables in the proposed model. Further results suggested that depression mediated all of the effects of psychotic symptoms on social maladjustment, but not all of their effects on well-being. Conclusions. In older patients with schizophrenia and other psychoses, health-related quality of well-being is influenced by symptoms of psychoses, psychosocial factors and social maladjustment. © 1997 by John Wiley & Sons, Ltd.     

Serum soluble L-selectin in childhood acute lymphoblastic leukemia

BACKGROUND: Determination of the serum level of soluble (s)L-selectin has been advocated for monitoring patient response to treatment in leukemia. The aim of the present study was to find out whether serum levels of sL-selectin correlated with treatment for acute lymphoblastic leukemia (ALL) in children. METHODS AND RESULTS: Serum samples were obtained from 30 children with ALL, either newly diagnosed during induction therapy, in remission, in maintenance therapy, at the end of treatment or after relapse. Levels of sL-selectin were assayed in the serum of children during the clinical course of ALL using the sandwich enzyme-linked immunoabsorbent assay. Serum sL-selectin concentrations decreased significantly from diagnosis to the end of intensive chemotherapy in children with ALL and increased in the time of relapse. CONCLUSION: These results suggest that monitoring of sL-selectin may be useful for evaluating leukemia activity.     

Effects of Stress and Beta1 Blockade on the Ventricular Depolarization Gradient of the Rate Modulating Pacemaker

Prism-CLR is a closed loop, rate modulating pacemaker that uses ventricular depolarization gradient (Gd) to continuously adjust heart rate. Heart rate response to a formal mental stress protocol, esmolol (500 mcg/kg bolus, 75-125 mcg/kg/min infusion), and mental stress during esmolol infusion were studied in six patients to investigate if Gd and paced heart rate response are under direct beta-adrenergic control. Paced heart rates increased in response to mental stress in a physiological manner (P less than 0.001). Response to esmolol infusion was paradoxical, with increased paced heart rates during esmolol bolus and infusion (P less than 0.05). There was no significant alteration in either systolic or diastolic blood pressure during mental stress or esmolol infusion (P greater than 0.05). Paradoxical increase in paced heart rates during esmolol administration suggests a primary or secondary effect of esmolol to decrease the ventricular depolarization gradient. This hypothesis was supported in four dog studies in which direct Gd measurements were made during esmolol infusion. Mental stress during esmolol infusion resulted in significantly increased paced heart rates (esmolol effect) with blunted changes in heart rate in response to the mental stress. The results of this study suggest that the physiological rate response during mental stress is attributable to sympathetic autonomic response.     

Cardiac Resynchronization Therapy:

In patients with heart failure and wide QRS complex, cardiac resynchronization therapy (CRT) is associated with improvement of symptoms and cardiac function. This study examined the effects of a 3-month period of CRT on left ventricular (LV) and right ventricular (RV) ejection fraction (EF) and on LV volumes, both at rest and during exercise. A CRT system was implanted in 15 patients with severe heart failure and wide QRS. Before implant and 3 months later, all patients underwent assessment of cardiac performance with equilibrium Tc⁹⁹ radionuclide angiography with imaging in the best septal left anterior oblique view. Exercise was performed on a bicycle ergometer. At 3 months, a significant improvement in New York Heart Association functional class was observed, and radionuclide angiography showed a significant decrease in LV volumes and a significant increase in LVEF at rest, as well as a significant increase in LVEF during exercise. The remodeling processes associated with CRT did not appear to include RV function, since RVEF did not improve, and changes in RVEF did not correlate with changes in LVEF, neither at rest nor during exercise.