PubMed Health⌕ Search

Biomedical subjects

Bengt Herweg

Publications and source records attributed to Bengt Herweg.

At least 19 recordsLinked to original sources
PubMed2006

Diagnostic value of the 12-lead electrocardiogram during conventional and biventricular pacing for cardiac resynchronization.

The paced 12-lead ECG is a valuable tool in the assessment of patients with pacemakers, and ideally should be recorded routinely at the time of implantation and during follow-up. It has become particularly important in patients undergoing cardiac resynchronization. The multiplicity of clinical situations described in this review highlight the pitfalls of using a single ECG lead in the overall evaluation of pacemaker patients. The design of programmers capable of registering a 12-lead ECG would obviate the need of an additional electrocardiograph and encourage the routine recording of the paced 12-lead ECG with each patient encounter. Such an arrangement would improve the care of pacemaker patients.

Arrhythmias, Cardiac↗
PubMed2006

Electrocardiographic diagnosis of myocardial infarction during left bundle branch block.

The electrocardiographic diagnosis of myocardial infarction (MI) in the presence of left bundle branch block (LBBB) has long been considered problematic or even almost impossible. Many proposed ECG markers in the old literature have now been discarded. However, the advent of reperfusion therapy has generated greater interest in the ECG diagnosis of acute MI in LBBB where ST-segment deviation is the only useful sign. As such, the ST-segment criteria cannot be used to rule out MI, but they can help to rule it in. Criteria for old MI (based on QRS changes) have not been reevaluated for almost 20 years and continue to exhibit low sensitivity, but high specificity.

Bundle-Branch Block↗
PubMed2006

Electrocardiographic diagnosis of myocardial infarction and ischemia during cardiac pacing.

For the diagnosis of myocardial infarction (MI) using the QRS complex, the ECG provides only a low sensitivity (25%) but high specificity (close to 100%), but one cannot determine the age of an MI from the QRS complex. Although one cannot determine with certainty the age of an MI (hours, days or even years) from a single ECG, the presence of primary ST-segment abnormalities strongly suggests the diagnosis of acute MI or severe ischemia and the possible need for emergency revascularization. For acute MI, ST elevation>or=5 mm in predominantly negative QRS complexes is the best marker with a sensitivity of 53%, and specificity of 88%. A recent investigation suggests that T wave abnormalities from ischemia can be differentiated from those caused by cardiac memory related to pacing.

Cardiac Pacing, Artificial↗
PubMed2006

Cardioversion in patients with left ventricular thrombus is not associated with increased thromboembolic risk.

OBJECTIVES: The purpose of the study was to define the incidence of systemic embolism after cardioversion in patients with left ventricular (LV) thrombus. BACKGROUND: The risk of systemic embolization after cardioversion in patients with an atrial thrombus is well known. However, data on thromboembolic events after cardioversion in patients with LV thrombus are limited because of hesitance to perform cardioversion in this population. METHODS: Transthoracic and transesophageal echocardiograms acquired between January 1996 and October 2001 at our institution were reviewed for presence of LV thrombus in two orthogonal apical views. A total of 413 patients had echocardiographic evidence of LV thrombus. Medical records were reviewed for cardioversion performed within 3 weeks of the echocardiogram. RESULTS: A total of 21 patients, age 66 +/- 10 years and ejection fraction 22 +/- 10% were identified. Cardioversion was indicated for atrial fibrillation in 8 (38%) and ventricular tachyarrhythmia in 13 (62%) patients, and was performed emergently in 5 (24%), electively in 8 (38%), and during electrophysiology study in 8 (38%) patients. The time interval between diagnostic echocardiographic study and cardioversion was 6 +/- 5 (range 1-18) days. All thrombi were located in the apical LV and were described as laminated (71%) and protruding (29%), and measured 0.7 +/- 0.4 x 1.6 +/- 0.8 cm. Before cardioversion, 17 (81%) patients were anticoagulated with warfarin or heparin. During clinical follow-up of up to 1 year (153 +/- 150 days) anticoagulation with warfarin was given to 15 (71%) patients. No patient had clinically apparent embolic event, including stroke, during hospitalization or during outpatient follow-up. CONCLUSIONS: Embolism after cardioversion in patients with echocardiographic evidence of LV thrombus was not observed. Cardioversion seems to be safe and further prospective studies are needed to address this.

Aged↗
PubMed2006

Latency during left ventricular pacing from the lateral cardiac veins: a cause of ineffectual biventricular pacing.

We report three patients with cardiomyopathy and pronounced stimulus to QRS latency during left ventricular (LV) pacing from an epicardial cardiac vein. Delayed LV activation during simultaneous biventricular pacing produced an electrocardiographic pattern dominated by right ventricular stimulation. Hemodynamic parameters improved immediately after advancing LV stimulation (in one patient) or pacing the LV only (in two patients) coupled with dramatic improvement of heart failure symptoms.

Cardiac Pacing, Artificial↗
PubMed2006

Mechanical esophageal deflection during ablation of atrial fibrillation.

To prevent esophageal damage during ablation of atrial fibrillation, we developed a technique to move the esophagus away from a desired ablation site too close to the esophagus. Under fluoroscopy, a transesophageal echocardiography probe was used to deflect the barium-opacified esophagus from the ablation site. This technique was successfully employed in three patients where critical sites of the posterior left atrial wall were very close to the esophagus.

Atrial Fibrillation↗
PubMed2005

Anatomic substrate, procedural results, and clinical outcome of ultrasound-guided left atrial-pulmonary vein disconnection for treatment of atrial fibrillation.

This report summarizes the efficacy, safety, and feasibility of intracardiac ultrasound (ICUS) and local electrographic-guided pulmonary vein (PV)-left atrial disconnection, including the isolation of common PV trunks accomplished in 170 consecutive patients with atrial fibrillation (AF). A left common PV was found in 43% of patients with AF. During a follow-up of 549 +/- 330 days after ablation, the AF-free survival rate was 80% and comparable in paroxysmal and persistent AF. PV stenosis was detected in only 1 asymptomatic patient, who required no intervention.

Adult↗
PubMed2005

Pulsus alternans caused by 2:1 left bundle branch block.

Pulsus alternans was caused by 2:1 left bundle branch block in a patient with a left ventricular ejection fraction of 50% and normal coronary arteries. The observations documented the profound depressant hemodynamic effect of complete left bundle branch block in the setting of minimal systolic left ventricular function.

Bundle-Branch Block↗
PubMed2005

Atrial gradient as a potential predictor of atrial fibrillation.

OBJECTIVES: We tested the utility and comparability of the atrial gradient and atrial ERP as early markers of electrical remodeling and a propensity to atrial fibrillation (AF). BACKGROUND: Pacing at physiologic rates from the left atrium alters the atrial gradient and is associated with atrial tachyarrhythmias. At these physiologic rates, there is no change in the atrial effective refractory period (ERP). METHODS: Sixty-one chronically instrumented mongrel dogs in complete heart block were paced from the left or right atrium at 400 to 900 bpm for 46 +/- 3 days. Dogs were monitored weekly and electrophysiologic studies conducted to determine changes in the atrial gradient, ERP, and rhythm. RESULTS: Rapid atrial pacing was associated with concordant decreases in atrial gradient, ERP, and occurrence of AF. Incidence of AF increased with increasing pacing rate. Although there ultimately was an equal incidence of AF with left atrial and right atrial pacing, the onset of AF occurred earlier with left atrial pacing. As expected, ERP decreased in both atria. Animals with long control ERP did not fibrillate. CONCLUSIONS: Rapid pacing induces changes in atrial gradient, which can be used as a noninvasive marker of electrical remodeling. AF is accompanied by decreases in atrial gradient and ERP, and the incidence is highest in dogs with short control ERP.

Animals↗
PubMed2005

Hypertension and hypertensive heart disease are associated with increased ostial pulmonary vein diameter.

INTRODUCTION: Atrial fibrillation (AF) is associated with increased ostial pulmonary vein (PV) diameter and commonly with hypertension. We sought to investigate ostial PV anatomy in patients with and without AF with the goal of characterizing the relationship to hypertension and cardiovascular disease. METHODS AND RESULTS: Ostial PV diameter was assessed by preprocedural spiral computed tomography in 100 AF patients undergoing a PV isolation procedure and in 24 age- and sex-matched non-AF control patients. Ostial diameter of 392 PVs in 100 AF patients was increased compared to 106 PVs in 24 non-AF controls (1.50 +/- 0.31 vs 1.20 +/- 0.31 cm, P <0.001) and diameters of individual PVs were uniformly affected (r=0.45-0.62, P <0.001). Left atrial dilation was associated with a larger PV diameter (1.56 +/- 0.32 vs 1.44 +/- 0.29 cm, P <0.01). PV diameter in AF patients with hypertension (1.55 +/- 0.32 cm), particularly if associated with left ventricular hypertrophy (1.66 +/- 0.37 cm), was larger compared to AF patients without hypertension (1.43 +/- 0.26 cm, P <0.01). PV diameter in control patients with hypertension (n=14) was larger than in those without hypertension (n=10, P <0.01). Patients with persistent AF had larger PV diameters (1.61 +/- 0.34 cm) than patients with paroxysmal AF (1.47 +/- 0.30 cm, P <0.01). Male gender (P <0.01), history of hypertension (P <0.01), and persistent AF (P <0.05) were identified as independent cofactors of increased ostial PV diameter. CONCLUSION: PV dilation affects all PVs uniformly in AF patients. Hypertension and hypertensive heart disease in patients with and without AF are associated with PV dilation, supporting theories that impaired left ventricular diastolic function is associated with a stretch-induced PV arrhythmia mechanism.

Anatomy, Cross-Sectional↗