PubMed Health⌕ Search

Biomedical subjects

B J Krenning

Publications and source records attributed to B J Krenning.

6 recordsLinked to original sources
PubMed2005

Long term outcome in patients with silent versus symptomatic ischaemia during dobutamine stress echocardiography.

OBJECTIVES: To compare the long term prognosis of patients having silent versus symptomatic ischaemia during dobutamine stress echocardiography (DSE). DESIGN: Observational study. SETTING: Tertiary referral centre. PATIENTS: 931 patients who experienced stress induced myocardial ischaemia during DSE. RESULTS: Silent ischaemia was present in 643 of 931 patients (69%). The number of dysfunctional segments at rest (mean (SD) 9.6 (5.1) v 8.8 (5.0), p = 0.1) and of ischaemic segments (3.5 (2.2) v 3.8 (2.1), p = 0.2) was comparable in both groups. During a mean (SD) follow up of 5.5 (3.3) years, there were 169 (18%) cardiac deaths and 86 (9%) non-fatal infarctions. Multivariable Cox regression analysis showed age (hazard ratio (HR) 1.1, 95% confidence interval (CI) 1.02 to 1.05), previous myocardial infarction (HR 1.4, 95% CI 1.1 to 2.0), and number of ischaemic segments during the test (HR 2.0, 95% CI 1.0 to 3.7) as independent predictors of cardiac death and myocardial infarction. For every additional ischaemic segment there was a twofold increment in risk of late cardiac events. The annual cardiac death or myocardial infarction rate was 3.0% in patients with symptomatic ischaemia and 4.6% in patients with silent ischaemia (p < 0.01). Silent induced ischaemia was an independent predictor of cardiac death and myocardial infarction (HR 1.7, 95% CI 1.1 to 2.0). During follow up symptomatic patients were treated more often with cardioprotective therapy (p < 0.01) and coronary revascularisation (145 of 288 (50%) v 174 of 643 (27%), p < 0.001). CONCLUSIONS: Patients with silent ischaemia had a similar extent of myocardial ischaemia during DSE compared to patients with symptomatic ischaemia but received less cardioprotective treatment and coronary revascularisation and experienced a higher cardiac event rate.

Angina Pectoris↗
PubMed2005

Three-dimensional echocardiography.

Three-dimensional (3-D) echocardiography has been an important research goal ever since the introduction of two-dimensional (2-D) echocardiography. Most approaches towards 3-D echocardiography were off-line and based on the sequential rotational scanning and acquisition of multiple cross-sectional images together with external or internal reference systems. These approaches were limited by long acquisition and analysis time in combination with poor image quality. Recently, improvements in the matrix array technology have significantly increased spatial and temporal resolution of second-generation real-time 3-D transducers. Clinical use of modern 3-D echocardiography is boosted by the marked reduction in acquisition time and the unique possibility of on-line rendering on the ultrasound system. The integration and future quantification of new parameters together with on-line review allows new insights into cardiac function, morphology and synchrony that offer great potentials in the evaluation of right and left global and regional function, diagnosis of small areas of ischemia, congenital and valvular heart disease and effects of biventricular pacing in dilated heart asynchrony. This report will review current and future applications of 3-D data acquisition, emphasizing the real-time methods and clinical applications of the new matrix array transducer.

Echocardiography, Three-Dimensional↗
PubMed2004

Feasibility of 3D harmonic contrast imaging.

Improved endocardial border delineation with the application of contrast agents should allow for less complex and faster tracing algorithms for left ventricular volume analysis. We developed a fast rotating phased array transducer for 3D imaging of the heart with harmonic capabilities making it suitable for contrast imaging. In this study the feasibility of 3D harmonic contrast imaging is evaluated in vitro. A commercially available tissue mimicking flow phantom was used in combination with Sonovue. Backscatter power spectra from a tissue and contrast region of interest were calculated from recorded radio frequency data. The spectra and the extracted contrast to tissue ratio from these spectra were used to optimize the excitation frequency, the pulse length and the receive filter settings of the transducer. Frequencies ranging from 1.66 to 2.35 MHz and pulse lengths of 1.5, 2 and 2.5 cycles were explored. An increase of more than 15 dB in the contrast to tissue ratio was found around the second harmonic compared with the fundamental level at an optimal excitation frequency of 1.74 MHz and a pulse length of 2.5 cycles. Using the optimal settings for 3D harmonic contrast recordings volume measurements of a left ventricular shaped agar phantom were performed. Without contrast the extracted volume data resulted in a volume error of 1.5%, with contrast an accuracy of 3.8% was achieved. The results show the feasibility of accurate volume measurements from 3D harmonic contrast images. Further investigations will include the clinical evaluation of the presented technique for improved assessment of the heart.

Contrast Media↗
PubMed2004

Pulsed wave tissue Doppler imaging for the quantification of contractile reserve in stunned, hibernating, and scarred myocardium.

OBJECTIVES: To assess whether quantification of myocardial systolic velocities by pulsed wave tissue Doppler imaging can differentiate between stunned, hibernating, and scarred myocardium. DESIGN: Observational study. SETTING: Tertiary referral centre. PATIENTS: 70 patients with reduced left ventricular function caused by chronic coronary artery disease. METHODS: Pulsed wave tissue Doppler imaging was done close to the mitral annulus at rest and during low dose dobutamine; systolic ejection velocity (Vs) and the difference in Vs between low dose dobutamine and the resting value (DeltaVs) were assessed using a six segment model. Assessment of perfusion (with Tc-99m-tetrofosmin SPECT) and glucose utilisation (by 18F-fluorodeoxyglucose SPECT) was used to classify dysfunctional regions (by resting cross sectional echocardiography) as stunned, hibernating, or scarred. RESULTS: 253 of 420 regions (60%) were dysfunctional. Of these, 132 (52%) were classified as stunned, 25 (10%) as hibernating, and 96 (38%) as scarred. At rest, Vs in stunned, hibernating, and scar tissue was, respectively, 6.3 (1.8), 6.6 (2.2), and 5.5 (1.5) cm/s (p = 0.001 by ANOVA). There was a gradual decline in Vs during low dose dobutamine infusion between stunned, hibernating, and scar tissue (8.3 (2.6) v 7.8 (1.5) v 6.8 (1.9) cm/s, p < 0.001 by ANOVA). DeltaVs was higher in stunned (2.1 (1.9) cm/s) than in hibernating (1.2 (1.4) cm/s, p < 0.05) or scarred regions (1.3 (1.2) cm/s, p = 0.001). CONCLUSIONS: Quantitative tissue Doppler imaging showed a gradual reduction in regional velocities between stunned, hibernating, and scarred myocardium. Dobutamine induced contractile reserve was higher in stunned regions than in hibernating and scarred myocardium, reflecting different severities of myocardial damage.

Cicatrix↗
PubMed2004

Prognostic value of dobutamine stress echocardiography in patients with previous coronary revascularisation.

OBJECTIVE: To assess the prognostic value of dobutamine stress echocardiography (DSE) in patients with previous myocardial revascularisation. DESIGN: Prospective study. SETTING: Tertiary referral centre in Rotterdam, the Netherlands. PATIENTS: 332 consecutive patients with previous percutaneous or surgical coronary revascularisation underwent DSE. Follow up was successful for 331 (99.7%) patients. Thirty eight patients who underwent early revascularisation (<or= 3 months) after the test were excluded from analysis. MAIN OUTCOME MEASURES: Cox proportional hazards regression models were used to identify independent predictors of the composite of cardiac events (cardiac death, non-fatal myocardial infarction, and late revascularisation). RESULTS: During a mean (SD) of 24 (20) months, 37 (13%) patients died and 89 (30%) had at least one cardiac event (21 (7%) cardiac deaths, 11 (4%) non-fatal myocardial infarctions, and 68 (23%) late revascularisations). In multivariate analysis of clinical data, independent predictors of late cardiac events were hypertension (hazard ratio (HR) 1.7, 95% confidence interval (CI) 1.1 to 2.6) and congestive heart failure (HR 2.1, 95% CI 1.3 to 3.2). Reversible wall motion abnormalities (ischaemia) on DSE were incrementally predictive of cardiac events (HR 2.1, 95% CI 1.3 to 3.2). CONCLUSIONS: Myocardial ischaemia during DSE is independently predictive of cardiac events among patients with previous myocardial revascularisation, after controlling for clinical data.

Echocardiography, Stress↗