Biomedical subjects

Otto Kamp

Publications and source records attributed to Otto Kamp.

43 records · Page 3Linked to original sources

PubMed2002

A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation.

BACKGROUND: Maintenance of sinus rhythm is the main therapeutic goal in patients with atrial fibrillation. However, recurrences of atrial fibrillation and side effects of antiarrhythmic drugs offset the benefits of sinus rhythm. We hypothesized that ventricular rate control is not inferior to the maintenance of sinus rhythm for the treatment of atrial fibrillation. METHODS: We randomly assigned 522 patients who had persistent atrial fibrillation after a previous electrical cardioversion to receive treatment aimed at rate control or rhythm control. Patients in the rate-control group received oral anticoagulant drugs and rate-slowing medication. Patients in the rhythm-control group underwent serial cardioversions and received antiarrhythmic drugs and oral anticoagulant drugs. The end point was a composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, implantation of a pacemaker, and severe adverse effects of drugs. RESULTS: After a mean (+/-SD) of 2.3+/-0.6 years, 39 percent of the 266 patients in the rhythm-control group had sinus rhythm, as compared with 10 percent of the 256 patients in the rate-control group. The primary end point occurred in 44 patients (17.2 percent) in the rate-control group and in 60 (22.6 percent) in the rhythm-control group. The 90 percent (two-sided) upper boundary of the absolute difference in the primary end point was 0.4 percent (the prespecified criterion for noninferiority was 10 percent or less). The distribution of the various components of the primary end point was similar in the rate-control and rhythm-control groups. CONCLUSIONS: Rate control is not inferior to rhythm control for the prevention of death and morbidity from cardiovascular causes and may be appropriate therapy in patients with a recurrence of persistent atrial fibrillation after electrical cardioversion.

Adrenergic beta-Antagonists↗

PubMed2002

Repeated assessment of coronary flow velocity pattern in patients with first acute myocardial infarction.

OBJECTIVES: The aim of this study was to evaluate the coronary blood flow velocity pattern immediately and 24 h after percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (AMI) in relation to myocardial reperfusion and follow-up left ventricular (LV) function. BACKGROUND: Analysis of coronary blood flow velocity pattern after AMI may provide information about microvascular damage and the occurrence of a reperfusion injury. METHODS: Measurement of coronary blood flow velocity pattern was performed immediately after PTCA and after 24 h in 25 patients with first AMI using a Doppler guidewire. Measurements were related to reperfusion determined by intravenous myocardial contrast echocardiography (MCE) performed before PTCA and at 24 h and to LV function at four weeks. RESULTS: Using MCE, 13 patients showed reperfusion and 12 patients showed nonreperfusion. Compared with patients with reperfusion, patients with MCE nonreperfusion had a lower systolic peak flow velocity immediately after PTCA (10.0 +/- 0.3 cm/s vs. 19.3 +/- 0.8 cm/s, respectively) and after 24 h (12.3 +/- 0.4 cm/s vs. 21.3 +/- 0.1 cm/s, respectively, p = 0.0022), more frequent early systolic retrograde flow (6/12 vs. 0/13, p = 0.0052 immediately after PTCA and 24 h later) and a shorter diastolic deceleration time immediately after PTCA (483 +/- 6 ms vs. 737 +/- 0 ms, respectively) and after 24 h (551 +/- 9 ms vs. 823 +/- 2 ms, respectively, p = 0.0091). Similarly, patients with impaired LV function at four weeks had altered coronary flow pattern compared with patients with preserved function. The coronary flow velocity pattern showed a tendency for improvement after 24 h in the reperfusion and the nonreperfusion groups. CONCLUSIONS: The coronary flow velocity pattern immediately and 24 h after PTCA for AMI relates to myocardial perfusion determined by MCE and LV function at four weeks. The flow velocity pattern shows slight improvement during the first 24 h after revascularization, indicating the absence of a major reperfusion injury.

Aged↗

PubMed2002

Determinants of brachial artery mean 24 h pulse pressure in individuals with Type II diabetes mellitus and untreated mild hypertension.

Brachial artery pulse pressure is a predictor of (cardiovascular) morbidity, but its determinants in individuals with Type II diabetes and untreated mild hypertension have not been elucidated. We therefore cross-sectionally investigated determinants of brachial artery mean 24 h pulse pressure in 60 individuals (40 males; age, mean +/- S.D., 57.8 +/- 7.5 years) with Type II diabetes [median diabetes duration (interquartile range), 6.3 (3.6-10.1) years] and untreated mild hypertension [sitting blood pressure >140/90 mmHg and <190/120 mmHg (mean of two consecutive auscultatory office measurements after 5 min of rest)]. We measured (1) three potential determinants reflecting different aspects of central artery stiffness [the overall systemic arterial compliance, the aortic augmentation index and 1/(regional carotido-femoral transit time)], (2) structural and functional changes of the circulatory system often observed in Type II diabetes, and (3) diabetes-associated metabolic variables. After adjustment for age, gender and mean arterial pressure, brachial artery pulse pressure was associated with autonomic function [standardized regression coefficient (beta), -0.27 (P=0.01)], blood pressure decline during sleep [standardized beta, -0.32 (P=0.002)], fasting glucose concentration [standardized beta, 0.26 (P=0.01)], HbA(1c) concentration [standardized beta, 0.27 (P=0.003)] and diabetes duration [standardized beta, 0.28 (P=0.002)] in linear regression analyses. In a combined multivariate model, brachial artery pulse pressure was independently determined by gender [1=male, 2=female; standardized beta, 0.24 (P=0.01)], diabetes duration [standardized beta, 0.18 (P=0.03)], mean arterial pressure [standardized beta, 0.32 (P=0.002)], systemic arterial compliance [standardized beta, -0.23 (P=0.02)] and fasting glucose concentration [standardized beta, 0.20 (P=0.02)]. Aortic augmentation index and 1/(carotido-femoral transit time) were not independently associated with pulse pressure. In conclusion, in individuals with Type II diabetes and untreated mild hypertension, brachial artery pulse pressure is determined mainly by proximal aortic stiffness in a way which is not strongly influenced by peripheral pulse wave reflection. Approx. 60% of the variance in brachial artery pulse pressure could be explained by potentially modifiable determinants.

Adult↗

PubMed2002

Importance of transducer displacement and tilting on three-dimensional echocardiographic volume assessment using apical or off-axis rotational acquisition: an in vitro study.

OBJECTIVE: The goal of this study was to assess effects of translation (horizontal displacement) and angulation (transducer tilting) on 3-dimensional (3D) echocardiographic volumes of both balloons and human left ventricles after autopsy. METHODS: Six water-filled (non-) aneurysmatic balloons of 150, 250, and 350 mL and 3 hearts of different sizes and shapes were suspended upright in a water bath. Angulation and/or translation was performed respectively by tilting the transducer with a mechanical arm in a vertical plane relative to the balloon tip or true apex of the hearts and by shifting the water bath in the same vertical plane. For balloon and left ventricular (LV) volume assessment, a 3D conical data set was obtained by TomTec rotational acquisition in combination with a HP Sonos 5500 ultrasound machine. RESULTS: For the 6 balloons, translation from 1 to 4 cm yielded volumes of up to 74% of the optimal volume (100%); angulation of 10 degrees or 20 degrees, volumes of up to 80% and 34%. Translation with 10-degree angulation yielded volumes up to 64%; for 20-degree angulation and translation, there was no volume loss. Results were similar for the left ventricles. CONCLUSIONS: Even minor angulation or translation of the transducer yields substantial underestimation of the true volume. Off-axis para-apical views, however, defined as angulation of 20 degrees and greater than 0.5 cm translation in this in vitro model, obviate volume underestimation. Such views in patients, if obtainable, may be an attractive alternative for conventional apical 3D acquisition, especially in dilated and aneurysmatic hearts.

Artificial Intelligence↗

PubMed2002

Intravenous myocardial contrast echocardiography predicts left ventricular remodeling in patients with acute myocardial infarction.

BACKGROUND: This study evaluated the ability of intravenous myocardial contrast echocardiography (MCE) performed in the setting of acute myocardial infarction for prediction of left ventricular (LV) remodeling. METHODS: Intravenous MCE was performed immediately before, 1 hour, and 24 hours after primary percutaneous transluminal coronary angioplasty (PTCA) in 35 patients with a first myocardial infarction. The MCE was used to define the relative perfusion defect size (in %; relMCD). Two-dimensional echocardiography was performed directly after angioplasty and after 4 weeks to determine LV end-diastolic volumes (LVEDV). The increase in LVEDV at 4 weeks defined a remodeling (> 15% increase) and a nonremodeling group (< or = 15% increase). RESULTS: Patients with remodeling had larger relMCD before (22.0 +/- 16.1 vs 8.0 +/- 11.9, P =.015), 1 hour (20.0 +/- 13.0 vs 4.9 +/- 11.6, P =.001), and 24 hours after PTCA (22.9 +/- 14.1 vs 1.2 +/- 2.8, P <.001). There was a significant correlation between relMCD 24 hours after PTCA and the increase in LVEDV at 4 weeks (r = 0.648; P <.001). Receiver operating characteristic (ROC) curve analysis revealed a relMCD at 24 hours of 5.1% or more to predict remodeling with a sensitivity of 94% and a specificity of 87% (area under ROC curve = 0.917; SE = 0.054). Multivariate analysis demonstrated relMCD at 24 hours to be the only predictor of remodeling (odds ratio = 173.4; P =.022). CONCLUSION: The size of the persistent MCE perfusion defect after revascularization for acute myocardial infarction has a high predictive value for LV remodeling during a 4-week follow-up period.

Aged↗

PubMed2002

Neither long-term treatment with raloxifene nor hormone replacement therapy modulate cardiac function in healthy postmenopausal women: two randomized, placebo-controlled, 2-year studies.

OBJECTIVE: Our purpose was to investigate the long-term effects of raloxifene, compared with opposed and unopposed estrogen replacement therapy, on echocardiographic parameters of left ventricular systolic function in healthy postmenopausal women. A total of 157 women were studied in 2 randomized, double-blind, placebo-controlled, 2-year studies. STUDY DESIGN: In study I, 60 postmenopausal women who had undergone hysterectomy received daily raloxifene, 60 mg (n = 15); raloxifene, 150 mg (n = 15); conjugated equine estrogens (CEE), 0.625 mg (n = 15); or placebo (n = 15). In study II, 97 postmenopausal women who had not undergone hysterectomy received daily raloxifene, 60 mg (n = 24); raloxifene, 150 mg (n = 24); CEE, 0.625 mg, plus medroxyprogesterone acetate (MPA), 2.5 mg (n = 24); or placebo (n = 25). M-mode, quantitative 2-dimensional and Doppler echocardiographic measurements were performed at baseline and after 1 and 2 years. RESULTS: Neither after 1 year nor after 2 years of treatment were echocardiographic parameters found to differ from baseline in both raloxifene groups, as well as in the unopposed CEE and the CEE/MPA groups, compared with the placebo group. CONCLUSION: Within 2 years of raloxifene treatment, no effect on echocardiographic parameters of left ventricular systolic function was found. Unopposed CEE or CEE/MPA also showed no effect.

Double-Blind Method↗

PubMed2002

Automatic segmentation of echocardiographic sequences by active appearance motion models.

A novel extension of active appearance models (AAMs) for automated border detection in echocardiographic image sequences is reported. The active appearance motion model (AAMM) technique allows fully automated robust and time-continuous delineation of left ventricular (LV) endocardial contours over the full heart cycle with good results. Nonlinear intensity normalization was developed and employed to accommodate ultrasound-specific intensity distributions. The method was trained and tested on 16-frame phase-normalized transthoracic four-chamber sequences of 129 unselected infarct patients, split randomly into a training set (n = 65) and a test set (n = 64). Borders were compared to expert drawn endocardial contours. On the test set, fully automated AAMM performed well in 97% of the cases (average distance between manual and automatic landmark points was 3.3 mm, comparable to human interobserver variabilities). The ultrasound-specific intensity normalization proved to be of great value for good results in echocardiograms. The AAMM was significantly more accurate than an equivalent set of two-dimensional AAMs.

Algorithms↗