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Norbert M van Hemel

Publications and source records attributed to Norbert M van Hemel.

11 recordsLinked to original sources
PubMed2006

Optimization of pulsed wave tissue Doppler to predict left ventricular reverse remodeling after cardiac resynchronization therapy.

OBJECTIVE: The optimal use of pulsed wave Doppler tissue imaging (DTI) in predicting left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT) was investigated. METHODS: DTI was performed in 69 patients before and 3 months after CRT. Echocardiographic reverse remodeling was observed in 38 patients. LV dyssynchrony was measured with the time to onset or peak systolic velocity in 2- and 6-basal segment models. RESULTS: The time to onset and either the standard deviation of 6 segments of > 20 ms or a delay of > or = 60 ms between any 2 of 6 segments had a similar predictive accuracy (sensitivity, 97% and 95%, respectively; specificity, 74% and 73%, respectively). The time to peak systolic velocity or evaluating 2 segments was less accurate. CONCLUSIONS: Evaluation of 6 segments is necessary to predict LV reverse remodeling after CRT. The time to onset of systolic velocity is superior to the time to peak velocity.

Aged↗
PubMed2005

The relevance of health related quality of life in paced patients.

With the tremendous advances in cardiac pacing during the past four decades, cardiac pacemaker implantation is now a common clinical procedure. In recent years, the indications for permanent pacemakers have expanded. This increase in reasons for pacing and shift in mode of pacing have been caused by the evolution of pacemaker therapy from a life-saving measure (mortality), to one aimed at improving health-related quality of life (HRQoL). Until now the efficacy of pacing therapy has predominantly been measured using "objective" criteria. However, in recent years the importance of HRQoL as an outcome measure has increasingly been recognized as patients prefer quality over quantity of life. In this review we describe the development and testing of Aquarel, a new developed HRQoL questionnaire for pacemaker patients, composed of a generic core module with disease specific add-ons. Current and future research to improve the Aquarel questionnaire is also described.

Cardiac Pacing, Artificial↗
PubMed2005

Electrical characteristics of low atrial septum pacing compared with right atrial appendage pacing.

AIM: The study was designed to compare the electrical characteristics of atrial leads placed in the low atrial septum (LAS) with those placed in the right atrial appendage (RAA) associated with dual chamber pacing. METHODS: In 86 patients an active-fixation (St. Jude Medical's Tendril DX model 1388T) atrial lead was positioned in RAA and in 86 patients the same model atrial lead was placed in the LAS. Pacing thresholds, sensing thresholds, impedances and the Far Field paced R-Wave (FFRW) amplitude and timing were compared at 6 weeks and at 3 and 6 months. RESULTS: The pacing threshold did not differ between groups. Sensed voltage of the P-wave was higher in the LAS compared with the RAA at 3 and 6 months (P=0.004). Impedance was higher in the LAS at 6 weeks and 3 months (P=0.002) but this difference was no longer significant at 6 months (P=0.05). The atrial sensed FFRW voltage was significantly higher in the LAS position compared with the RAA at 3 and 6 months follow-up (P=0.0002). FFRW voltage>1 mV was seen in 87% of the RAA pacing group and in 94% of the LAS pacing group (P=ns). The time between the ventricular pacing stimulus and the sensed FFRW in the atrium, (V spike-FFRW) in RAA was longer than in LAS at all follow-up measurements (P=0.006). CONCLUSIONS: The electrical characteristics of LAS pacing makes this alternative position in the atrium safe and feasible. Though statistical differences were found in P-wave sensing (LAS higher voltage than in the RAA) and FFRW sensing was higher in the LAS compared with the RAA this did not interfere with the clinical applicability of the LAS as alternative pacing site.

Atrial Fibrillation↗
PubMed2005

Pacemaker-related myocardial perfusion defects worsen during higher pacing rate and coronary flow augmentation.

BACKGROUND: Asynchronous activation resulting from right ventricular apical (RVA) pacing can adversely affect left ventricular function and myocardial perfusion despite normal coronary arteries. This situation makes detection of coronary heart disease in paced patients difficult. OBJECTIVES: The purpose of this study was to assess the distribution, extent, and severity of myocardial perfusion defects with RVA pacing at low and high rates and increased coronary blood flow with adenosine. METHODS: Fourteen patients with permanent RVA pacing and angiographically normal coronary arteries underwent myocardial perfusion single-photon emission computed tomography at rest at low and high pacing rates and with pacing at low rates with adenosine. Data were analyzed semi-quantitatively using a 20-segment scoring model and coded using a four-point scoring system. RESULTS: At rest, 23 (55%) of 42 coronary flow territories showed abnormal perfusion and 52 (19%) of 280 corresponding segments demonstrated abnormal perfusion; mean perfusion score was 0.22. After high-rate pacing, perfusion was abnormal in 31 (74%) of 42 flow territories and 122 (44%) of 280 segments; mean perfusion score was 0.67. Adenosine infusion resulted in 28 (67%) of 42 abnormal flow territories and 90 (32%) of 280 abnormal segments; mean perfusion score was 0.44. Perfusion defects were observed most often in close proximity to the origin of the pacing site. CONCLUSION: RVA pacing results in myocardial perfusion defects. The false-positive findings are present at rest and more obvious with high-rate pacing than during adenosine infusion. Detection of coronary artery disease should be performed with caution in RVA paced patients because of the high number of perfusion defects observed in the absence of coronary artery disease.

Adenosine↗
PubMed2004

Properties of unipolar electrograms recorded with a multielectrode basket catheter.

In the past few years, clinical trials with multielectrode "basket" catheters have provided unique recordings from the endocardium of intact in-situ human hearts. Analysis of these recordings is difficult because unipolar electrograms obtained from a basket catheter in the blood-filled cavity differ from those obtained by other mapping techniques such as endocardial balloons used during antiarrhythmic surgery. We investigated these differences using basket catheter recordings obtained in isolated porcine and canine hearts that could be filled with perfusion fluid and evacuated at will. The results indicated that the differences between basket and balloon recordings are largely attributable to the presence and absence of blood. Activation maps obtained in the presence and absence of blood were usually similar and only differed in a minority of cases at sites in which electrograms revealed multiple deflections. In conclusion, unipolar mapping using a basket catheter can be used with confidence for the creation of activation maps if appropriate care is taken in the interpretation of fractionated electrograms.

Animals↗
PubMed2004

Maze procedure.

Explore the source record for details and available documents.

Atrial Fibrillation↗
PubMed2003

The effect of maze operations on atrial volume.

BACKGROUND: Unmodified maze III operations show long-term eradication of atrial fibrillation (AF) in more than 85% of patients with or without structural heart disease. The effect of this procedure on atrial volumes is not known. METHODS: Two patient populations were studied: (1) patients undergoing unmodified maze III operations combined with surgical structural heart disease, mostly mitral valve operations (group A; n = 32); and (2) patients with only AF selected for unmodified maze III operations (group B; n = 32). In groups A and B, transthoracic Doppler echocardiographic studies were prospectively made preoperatively, and at 3 and 12 months postoperatively. Left and right atrial dimensions and volumes and atrial contractions were determined and compared with base line patient characteristics and 12 months arrhythmia outcomes. RESULTS: One year postoperatively all patients were alive. In groups A and B, 92% were free of AF and other atrial arrhythmias. A significant reduction of left atrial volume at 1 year postoperatively was apparent in group A, whereas the left atrial volume did not change significantly in group B. The reduction observed in group A was not related to postoperative age, type or duration of AF, or late atrial arrhythmia outcome. In both groups the right atrial volume remained unchanged at 12 months postoperatively. CONCLUSIONS: The unmodified maze III operation does not affect atrial volume in patients without structural heart disease. In patients with structural heart disease, the mitral valve operation contributes to the reduction of left atrial volume and dimension by improving the hemodynamic condition.

Atrial Fibrillation↗
PubMed2003

The accuracy of 1-day dual-isotope myocardial SPECT in a population with high prevalence of coronary artery disease.

BACKGROUND: In order to evaluate the diagnostic efficacy of the 1-day separate acquisition dual-isotope single-photon emission computed tomography (SPECT) protocol, using 201Tl for the rest and 99mTc-tetrofosmin for the stress images, a consecutive series of patients with suspected or known coronary artery disease (CAD) was studied that also underwent coronary angiography. METHODS: The results of myocardial SPECT, using a semi-quantitative visual analysis, were acquired in 123 patients and compared with the results of coronary angiography. Sensitivity and specificity were calculated, using thresholds of > or = 50 and > or = 70% stenosis. As an alternative for specificity, the normalcy rate was determined in a separate group of 87 patients with a < 5% pre-test likelihood of CAD. RESULTS: The prevalence of CAD using > or =50 and > or = 70% stenosis was 88 and 78%, respectively. The sensitivity for detection of patients with > or = 50 and > or = 70% stenosis was 94 and 97%, respectively while specificity was 62 and 59%, respectively. The high rate of false positive perfusion defects resulting in a low specificity could be explained by specific clinical issues. However, the routine assessment with additional clinical and electrocardiographic data resulted in a correct interpretation of most of the false positive perfusion defects. The positive predictive value was 92 and 85% and the negative predictive value 46 and 77%, using thresholds of > or = 50 and > or = 70% stenosis, respectively. The normalcy rate was 91%. CONCLUSION: The one-day separate acquisition rest 201Tl/stress 99mTc-tetrofosmin SPECT protocol is an efficient procedure for myocardial perfusion scintigraphy with high sensitivity for detection of CAD. Specific clinical issues caused a low value for specificity. Therefore, clinical information and knowledge of the electrocardiogram is essential for a correct interpretation of SPECT images.

Adenosine↗
PubMed2002

Contribution of body surface mapping to clinical outcome after surgical ablation of postinfarction ventricular tachycardia.

This article investigates the influence of body surface mapping on outcome of ventricular antiarrhythmic surgery. Preoperative mapping is advocated to optimize map-guided antiarrhythmic surgery of postinfarction ventricular tachycardia. We sequentially analyzed the results of catheter activation sequence mapping, body surface mapping, and intraoperative multielectrode mapping in 54 patients and made a comparison with 30 control patients (group B) in whom catheter activation sequence mapping was omitted. Endpoints were actuarial survival, freedom of arrhythmia, and comparability of the localisation of sites of ventricular tachycardia origin. A total of 128 morphologically different monomorphic sustained ventricular tachycardias were mapped in group A. In group A, 87 ventricular tachycardias were mapped preoperatively with body surface mapping and 30 ventricular tachycardias with catheter activation sequence mapping. In 19 of 24 ventricular tachycardias (79%) that were localized with both mapping methods the ventricular tachycardia exit site was similar. In-hospital death was 1 of 85 (1.2%). Actuarial freedom from ventricular arrhythmias at 4-year follow-up was 74.1 +/- 6.0% in group A vs. 90.0+/-5.5% in group B (P =.10). In group A 14 of 54 patients died (29.6%), whereas 4 of 30 patients (13.3%) died in group B (P =.09). Arrhythmia freedom and survival is as good in patients mapped with body surface mapping only as in patients mapped with body surface mapping and catheter activation sequence mapping.

Aged↗
PubMed2001

Incremental prognostic value of myocardial SPET with dual-isotope rest (201)Tl/stress (99m)Tc-tetrofosmin.

The incremental prognostic value of dual-isotope myocardial perfusion scintigraphy using technetium-99m tetrofosmin for the stress images was evaluated in 597 consecutive patients with known or suspected coronary artery disease. We used semi-quantitative visual analysis with a five-point scoring system and calculated the summed stress score, the summed rest score and the summed difference score. During the 2-year follow-up period, 46 "hard" cardiac events occurred: 16 cardiac deaths and 30 non-fatal myocardial infarctions. Kaplan-Meier analysis demonstrated a favourable prognosis for patients with normal scans as compared with patients with mildly to moderately or severely abnormal scans ( P<0.001). Multivariate analysis demonstrated incremental prognostic information for nuclear variables. A very low rate of hard cardiac events was observed in patients with a low summed stress score. Thus, nuclear variables provide incremental prognostic information and could be used to guide the management process with respect to whether or not to proceed with further invasive procedures.

Adult↗