Richard M. T. Lu

A conceptual model of data warehousing for medical device manufacturers

Required information for management decisions in an organization can span across many internal functions and external sources, particularly for decisions with strategic ramifications. In recent years, increasing numbers of organizations have employed data warehouses to meet their needs of accurate and timely information. A literature research has been performed to understand data warehousing applications in the healthcare and pharmaceutical industry. With lessons learned from these applications and situation analyses of medical device organizations, a conceptual model of data warehousing for medical device manufactures is proposed. This model proposes an enterprise-wide data warehouse, which will link information generated or obtained from different local systems. This data warehouse is the focal point of an integrated system where data from all sources are stored in predefined formats and will provide information of interest to various users in the organization. Some practical applications of such an integrated data warehouse in areas of product portfolio planning, sales/marketing, and clinical/regulatory are discussed. The future trends of data warehousing applications for medical device manufacturers are also envisioned.

Distinguishing Ventricular Fibrillation From Noise Using The Paced Depolarization Integral

The discrimination of ventricular fibrillation from noise interference can be problematic in an implantable arrhythmia control device. This study investigated the electrogram following a pacing stimulus as a metric to distinguish ventricular fibrillation from normal sinus rhythm during the injection of electrical noise. The electrogram at the pacing site was low pass filtered and integrated to obtain the paced depolarization integral. Results from six animal studies indicated that when compared with normal sinus rhythm, the paced depolarization integral markedly decreased during ventricular fibrillation and so could distinguish ventricular fibrillation from normal sinus rhythm during injected noise interference.

Clinical significance of a new P wave lead vector for pacemaker follow-up of atrial functions.

Patient welfare requires routine follow‐up procedures of implantable pacemakers. However, the assessment of atrial sensing and pacing functions in implantable pacemakers is often a challenge due to difficult identification of low amplitude P waves on surface electrocardiograms (ECGs). A previous body surface mapping study suggested that a novel P wave lead vector (P lead) had larger root mean square values than other standard leads. However, for pacemaker follow‐up procedures, peak‐to‐peak amplitudes are more relevant than root mean square values. In this study, the peak‐to‐peak amplitudes of intrinsic and paced P waves recorded from surface ECG standard lead II and the P lead were compared. In addition, intrinsic and paced R waves were also compared. Data recorded from 15 patients undergoing electrophysiological studies indicated that peak‐to‐peak amplitudes of the P lead were significantly larger than standard lead II: 24% for intrinsic P waves, 30% for paced P waves, and 72% for intrinsic R waves. In addition, the P lead amplitude of paced R waves showed a nonsignificant increase of 24% compared with standard lead II. Therefore, the use of this new lead vector may improve the clinical ease‐of‐use and reduce the time required for follow‐up procedures of implantable pacemakers for atrial sensing and pacing assessments.

The Measurement of the Paced Depolarization Integral Using the Braided Endocardial Lead

Previous studies have shown that the paced depolarization integral (PDI) data recorded in unipolar configuration could potentially improve the specificity of tachyarrhythmia classification in an implantable cardioverter defibrillator (ICD). However, the defibrillation protection would be compromised if the ICD case were used as an indifferent electrode. Since transvenous defibrillation leads are being investigated to be used with ICDs, this study determined if reliable PDI data could be obtained using the braided endocardial defibrillation lead (BEDL), The results demonstrated that comparable PDI values and PDI changes with epinephrine induced sinus tachycardia were obtained with all three tested sensing configurations: conventional unipolar, tip electrode to right ventricular defibrillation electrode, and tip electrode to superior vena cava defibrillation electrode. Therefore, the BEDL can be used to measure PDI data, which possibly may improve tachyarrhythmia classification in an ICD, without compromising its defibrillation protection.

Ventricular fibrillation detection using the evoked electrogram from the braided endocardial defibrillation lead

Life-threatening consequences can be the result of inappropriate classification of ventricular fibrillation for patients with implantable cardioverter defibrillators. The objective of this study was to determine if analysis of the asynchronously paced evoked electrogram using the braided endocardial defibrillation lead could improve the detection of ventricular fibrillation. The depolarization portion of the evoked electrogram was integrated to obtain the paced depolarization integral. The results demonstrated that the mean of the paced depolarization integral, its SD, and the mean +/- SD were significantly different between sinus rhythm and ventricular fibrillation (p < 0.005, p < 0.05, p < 0.01, respectively). These results suggest that the paced depolarization integral obtained with the braided endocardial defibrillation lead could improve the specificity and sensitivity of ventricular fibrillation detection.

The effect of respiration on the paced depolarization integral

The paced depolarization integral is the integral of the paced electrogram at the pacing site during ventricular depolarization. The paced depolarization integral has been used as a rate control parameter for a rate responsive pacemaker. Studies also have shown that the paced depolarization integral has the potential to be used for tachyarrhythmia differentiation. In this study, the effect of positive pressure respiration on the paced depolarization integral was investigated. It was found that the paced depolarization integral could be modulated significantly by changing the ventilation modes in animals.