PubMed Health⌕ Search

Biomedical subjects

Ernest W Lau

Publications and source records attributed to Ernest W Lau.

12 recordsLinked to original sources
PubMed2005

One heart, two minds.

A case of complex atrial tachyarrhythmias following orthotopic heart transplantation is presented. The ablation strategy in such a situation and the outcome achieved are discussed.

Adult↗
PubMed2005

Acupuncture triggering inappropriate ICD shocks.

Acupuncture is a modality of alternative medicine popular certain sectors of society. The possible interaction between acupuncture and ICD therapy has not been previously investigated. A case of acupuncture triggering inappropriate shocks from the ICD is reported.

Acupuncture↗
PubMed2004

Preexcitation masking underlying aberrant conduction: an atriofascicular accessory pathway functioning as an ectopic right bundle branch.

Preexcitation and aberrant conduction both cause a broad QRS complex. An unusual case of an atriofascicular accessory pathway effectively functioning as an ectopic right bundle branch and responsible for both physiologically normal ventricular activation and pathologic preexcited tachycardias as part of a split AV node-bundle branch system is presented.

Adult↗
PubMed2004

Isorhythmic interaction between a dual-chamber pacemaker and an intrinsic rhythm: pacemaker malfunctioning or not?

A patient underwent cardiac surgery (including a biatrial maze procedure) for congenital heart disease and paroxysmal atrial tachycardia. Previously, a dual-chamber pacemaker was inserted for bradycardia. Postoperative ECG showed a narrow complex rhythm interspersed with pacing stimuli that appeared premature and unable to capture. The phenomenon was due to isorhythmic interaction between the pacemaker and the patient's own intrinsic rhythm, which is compatible with normal pacemaker functioning. The different patterns possible for the phenomenon and the necessary conditions for their occurrence are elucidated.

Bradycardia↗
PubMed2002

A streamlined "3-catheter" approach in the electrophysiological study and radiofrequency ablation of narrow complex tachycardia.

BACKGROUND: Electrophysiological study (EPS) followed by radiofrequency (RF) ablation has emerged as the treatment of choice for symptomatic narrow complex tachycardia (NCT), for which purpose, 5 catheters are typically used (4 for the initial EPS and an additional one for the subsequent RF ablation). We describe an alternative, streamlined approach using only 3 catheters [2 standard (diagnostic) and 1 deflectable, thermistor tip (mapping)] as the standard configuration for EPS and RF ablation in patients with NCT but no pre-excitation on ECG. METHODS AND RESULTS: Diagnosis was obtained in all 250 consecutive patients (mean age 45 years, 174 females): atrio-ventricular nodal re-entrant tachycardia (AVNRT) in 188 (75%), concealed accessory pathways (AP's) in 38 patients (15%), ectopic atrial tachycardia in 19 patients (8%), persistent junctional re-entrant tachycardia (PJRT) in 4 patients (2%) and atrial fibrillation in 1 patient. An additional diagnostic catheter was used for optimising atrial pacing in 3 patients and for ventricular pacing in concealed right postero-septal AP's in another 3. An additional mapping catheter was used in 31 patients with concealed left-sided AP's, 2 with multiple AP's and 1 with PJRT. Three patients had complications (1 pulmonary embolism, 1 pericardial effusion and 1 atrio-ventricular node block). Overall, the immediate success rate was 98% (224/229) with a recurrence rate of 4.4% (10/224), and the total success rate (with repeat RF ablation if necessary) was 99.2% (227/229) over a median follow-up period of 31.4 months. The average cost saving was US$474 per procedure. Procedure duration (2.0 +/- 0.1 hours), fluoroscopy time (13 +/- 1 minutes) and the number of radiofrequency applications (5.4 +/- 0.3) also compared favourably with values reported in the literature for RF ablation of AVNRT. CONCLUSION: Compared to the conventional 5-catheter configuration for the combined EPS and RF ablation procedure in treatment of patients with NCT, the described 3-catheter configuration reduces cost, procedure duration and fluoroscopy time without compromising on success rate and safety. On these bases, we advocate its widespread adoption.

Adolescent↗
PubMed2002

Comparison of the performance of three diagnostic algorithms for regular broad complex tachycardia in practical application.

The authors previously proposed a Bayesian approach to the electrocardiographic diagnosis of regular broad complex tachycardia (BCT), which can be due to VT or supraventricular tachycardia with aberrant conduction (SVTAC). They also published an account comparing the theoretical merits in the design of two of the most commonly used diagnostic algorithms for the same purpose, those of Brugada et al. and Griffith et al. In this study, a direct head-to-head comparison was performed on the practical performances of the three algorithms in this study. A set of 111 ECGs showing regular BCT (77 VT, 34 SVTAC) whose diagnoses were confirmed by electrophysiological study was shown to five internists in general medicine at a district general hospital. The observers were asked to comment on whether the ECG criteria in the three algorithms tested were fulfilled or not, and a computer program then derived the corresponding diagnoses. The sensitivity and specificity for VT achieved by the Brugada algorithm were 92% and 44%, 92% and 44% by the Griffith algorithm, and 97% and 56% by the Bayesian algorithm. The Bayesian algorithm achieved a higher sensitivity and specificity than the other two algorithms, but the differences are not statistically significant (P = 0.6583 and P = 0.5334, respectively). The Brugada, Griffith, and Bayesian algorithms show comparable performances in terms of overall sensitivity and specificity when tested in practice. Of the three algorithms, the Griffith algorithm excels in simplicity and is the easiest to implement in practice. The Bayesian algorithm achieved slightly higher values for sensitivity and specificity than the Brugada and Griffith algorithms but may be more suitable for automated computer-aided diagnosis of ECG due to its complexity.

Algorithms↗
PubMed2002

The reliable electrocardiographic diagnosis of regular broad complex tachycardia: a holy grail that will forever elude the clinician's grasp?

The reliable and accurate diagnosis of regular broad complex tachycardia (BCT) by the ECG is a goal that has eluded clinicians and electrophysiologists alike for years. This article explores the reason for this by first giving an historical account on the development of the subject. Next, the electrophysiological mechanisms of ventricular tachycardia, supraventricular tachycardia with aberrant conduction, and preexcited tachycardia, the three main differential diagnoses for regular BCT, according to the latest knowledge from cellular and clinical electrophysiology study will be reviewed, together with considerations on how such understanding may help account for the manifestations of these tachycardias on the ECG and the difficulty in distinguishing between them. Finally, the use of electrophysiological study as the criterion standard for diagnosing regular BCT, as has been the case in most studies on the subject, will be critiqued in terms of the potential for misdiagnosis by the method and the use of any ECG diagnostic algorithms developed with its aid in the acute medical care setting.

Algorithms↗
PubMedDate not supplied

Visual illusions created by survival curves and the need to avoid potential misinterpretation.

Randomized clinical trials play an increasingly important role in guiding management decisions, and survival curves are the most popular means for summarizing and depicting the results of a clinical trial. However, survival curves may create certain "visual illusions" that can be misinterpreted by the unwary, with potentially adverse effects on patient care. The authors provide a brief outline of the theoretical background of survival curves and explain the origin of the most common visual illusions. Statisticians need to be aware of such potential for misinterpretation of clinical trial data in order to safeguard clinicians against drawing undue inferences and applying them to actual practice.

Humans↗