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Biomedical subjects

Lorne J Gula

Publications and source records attributed to Lorne J Gula.

29 records · Page 2Linked to original sources
PubMed2005

Central venous occlusion is not an obstacle to device upgrade with the assistance of laser extraction.

OBJECTIVE: To assess the efficacy and safety of laser-assisted lead extraction for upgrade of existing pacemakers and defibrillators in patients with central venous obstruction. BACKGROUND: Implantable cardiac defibrillators and biventricular pacing have become the accepted therapeutic measures for patients with congestive heart failure. Many patients who are candidates for device therapy, however, already have existing right ventricular leads and the presence of central venous obstruction. Upgrade of existing devices in these patients is a dilemma, which is increasingly encountered by device-implanting physicians. Laser-assisted extraction of existing leads can facilitate access for device upgrade and provide an alternative to lead abandonment and contralateral implant. METHODS: We review our experience with laser-assisted lead extraction in patients, referred for upgrade of existing devices, who were found to have, or known to have, ipsilateral subclavian vein occlusion. RESULTS: Over the past 3 years, 18 patients (13 men, 5 women; mean age 63.9 +/- 16 years) with subclavian vein occlusion underwent successful laser-assisted lead extraction (total 29 leads) and upgrade of existing leads to defibrillators and/or biventricular systems. Mean implant duration prior to extraction was 70.8 +/- 43.5 (11-192) months. Cannulation of the coronary sinus and placement of a transvenous left ventricular lead were achieved in all 13 patients in whom it was attempted. No complications occurred. CONCLUSIONS: Laser-assisted lead extraction is a safe and effective approach, allowing for ipsilateral device upgrade in patients with existing devices and central venous obstruction.

Adult↗
PubMed2005

Unusual QRS morphology on ECG: a rare condition and an interesting response to pacing.

We present the interesting case of a young man with borderline wide QRS complexes noted on electrocardiogram (ECG). The diagnosis of an unusual form of preexcitation was reached using observations from intracardiac tracings at electrophysiology study. Atrial pacing consistently resulted in further widening of the first conducted QRS complex, and the physiology underlying this unusual finding is explored.

Adult↗
PubMed2005

Primary prophylaxis of sudden death in hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and dilated cardiomyopathy.

We present an evidence-based overview of primary prevention of sudden cardiac death. Several recent studies have provided important data regarding pharmacologic and device-based therapy for patients with conditions that confer high risk for sudden death. A rational approach to these therapies, with emphasis on implanted cardiovertor defibrillators, is discussed.

Anti-Arrhythmia Agents↗
PubMed2004

External loop recorders: determinants of diagnostic yield in patients with syncope.

OBJECTIVES: The purpose of the current study was to determine the optimal duration of external loop recorder (ELR) monitoring in patients with presyncope or syncope and to identify factors that predict failure to activate the device effectively. DESIGN: A multivariate analysis was performed using data from the Comparison Of Loop Recorders Against Holter in Patients with Syncope (COLAPS) trial, a prospective study comparing diagnostic utility of ELRs and Holter monitors for assessment of syncope. METHODS: Patients with failure to effectively activate ELRs were compared to those who were successful. This analysis was performed separately for failure of test transmission and for failure to successfully record and transmit data from symptomatic episodes. Patient characteristics were compared among the groups to determine risk factors for device failure. RESULTS: Among 78 patients who received ELRs, a test transmission was successfully performed by 84.5% of patients. Twenty-one percent of diagnoses were made within 48 hours, 50% at 15 days, and 90% at 33 days. Patients performing a successful test transmission were more familiar with technology, with ability to use a bank automatic teller machine being a significant independent predictor. Patients with a successful test transmission were, in turn, significantly more likely to record and transmit data from symptomatic episodes. Patients living alone were much less likely to use the loop recorder effectively. The presence of factors that may influence motivation to reach a diagnosis (degree of worry/fear of symptoms and impact on daily life) were associated with successful use of the device in a univariate analysis. CONCLUSION: ELRs should be worn for at least 30 days to maximize their diagnostic yield. Patients who are unfamiliar with technology, live alone, or have low motivation to reach a diagnosis have a lower diagnostic yield from ELRs for assessment of syncope.

Electrocardiography, Ambulatory↗
PubMed2004

Novel approach to diagnosis of a wide-complex tachycardia.

Despite sophisticated atrial and ventricular pacing techniques used during electrophysiologic study, the exact mechanism of some tachycardias remain elusive. In this situation, eliminating conduction from specific tissue and observing the effect on the tachycardia can be diagnostic. Such a maneuver can be performed using the technique of ice mapping, which entails reversible cooling of tissue to test function prior to delivery of a permanent ablation lesion. We present a case of wide-complex tachycardia with inconclusive results from diagnostic electrophysiologic study. Using ice mapping, cooling at the region of the compact AV node resulted in block in the ascending fast pathway. When cooling subsequently was applied to the region of the slow pathway, tachycardia broke in the descending limb; thus AV nodal reentrant tachycardia was diagnosed on an anatomic and functional basis.

Catheter Ablation↗
PubMed2003

Heart rate variability in obstructive sleep apnea: a prospective study and frequency domain analysis.

BACKGROUND: Cyclic variation of the heart rate is observed during apneic spells in obstructive sleep apnea (OSA). We hypothesized that autonomic changes would affect frequency-domain measures of heart rate variability (HRV). METHODS: We studied 20 patients (15 men, 5 women, mean age 47.2 +/- 12.2 years) with suspected OSA undergoing overnight polysomnography, and five patients (4 men, 1 woman, mean age 49.2 +/- 8.6 years) with recently diagnosed sleep apnea undergoing polysomnography while wearing continuous positive airway pressure (CPAP). Holter monitors were applied during sleep studies and data were analyzed in 5-minute blocks over the course of the night. Using spectral analysis, low frequency (LF) and high frequency (HF) powers were calculated for each interval. Overall mean and standard deviation (SD) for LF power, HF power, and the LF:HF ratio were recorded for each patient. Comparisons were made between patients with severe OSA (apnea hypopnea index (AHI) > 30, n = 8), moderate OSA (AHI 1-30, n = 5), without OSA (AHI < 10, n = 7), and patients wearing CPAP (n = 5). RESULTS: Assessment of overnight LF or HF power revealed no significant difference between the four groups. The LF:HF ratio, which represents sympathovagal balance, was higher among those with moderate disease compared to normals and those with severe OSA (both P = 0.037). The standard deviation of the LF:HF ratio was higher among those with moderate disease compared to normals (P = 0.0064) and those with severe OSA (P = 0.0006). OSA patients receiving CPAP behaved like patients with moderate OSA, with increased SD of the LF:HF ratio. CONCLUSIONS: The observed changes in the LF:HF ratio and its SD suggest an increased sympathetic tone and discordance in sympathovagal activity in moderate OSA, which is blunted in severe OSA. CPAP may restore autonomic defects, characteristic of severe OSA, to moderate levels.

Adult↗
PubMed2003

Diagnosing acute myocardial infarction in the setting of left bundle branch block: prevalence and observer variability from a large community study.

BACKGROUND: Despite the known benefit of thrombolysis it remains under-utilized among eligible patients with acute myocardial infarction (AMI) and left bundle branch block (LBBB). We sought to determine the test characteristics and observer reliability of well-known criteria for the diagnosis of AMI when LBBB is present on the electrocardiogram (ECG). METHODS: Four hundred and fourteen ECGs with LBBB from a large cohort of AMI patients (7.4% of the total) and 85 ECGs with LBBB not in the setting of acute coronary syndromes were interpreted for the presence of the Sgarbossa criteria. RESULTS: Agreement for the various Sgarbossa criteria ranged from only fair to moderate. The three-way comparison kappa values were significantly better for ST depression than for both discordant (P<0.001) and concordant (P=0.001) ST-segment elevation. Concordant ST-segment elevation [6.3%, 95% confidence interval (CI) 4.3-9.1%] and depression (3.1%, 95% CI 1.8-5.4%) were infrequently seen in the setting of AMI and rarely seen otherwise. Discordant ST-segment elevation was seen more frequently (19.0%, 95% CI 15.5-23.1%). Concordant ST elevation and ST depression in V1-V3 were highly specific, but insensitive, for the diagnosis of AMI. The presence of discordant ST elevation was neither sensitive nor specific. CONCLUSION: The low prevalence, poor sensitivity and marked observer variability make the Sgarbossa criteria for AMI in the setting of LBBB less than adequate. Although use of these criteria would be an advance over contemporary practice, it would still fall short among this high-risk subset.

Bundle-Branch Block↗
PubMed2002

Pyopneumopericardium caused by mediastinal granuloma.

We report the case of a previously healthy 32-year-old man who was seen with flulike symptoms, dyspnea, and chest pain. The diagnosis was pyopneumopericardium, and pericardial tap revealed 1.3 L of purulent material. Computed tomography of the chest demonstrated a calcified mass inferior to the carina. Urgent exploration through a right thoracotomy revealed that the mass was adherent to the esophagus and pericardium. The subcarinal mass was resected. Pathological study demonstrated granulomatous lymph nodes, which were likely due to histoplasmosis. This is among the first reports of granulomatous erosion into the pericardium causing pyopneumopericardium. The patient made a good recovery, and his case demonstrates the importance of early imaging and mediastinal exploration for pyopneumopericardium.

Adult↗