Biomedical subjects

Ralf Koos

Publications and source records attributed to Ralf Koos.

24 records · Page 2Linked to original sources

PubMed2004

Comparison of left ventricular lead placement via the coronary venous approach versus lateral thoracotomy in patients receiving cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is a new therapeutic option in patients with heart failure and ventricular conduction delay. We compared the long-term performance of left ventricular (LV) pacing via the coronary venous (CV) approach and a limited lateral thoracotomy (LLT). Data from 81 patients (age 65 +/- 12 years; 52 men, New York Heart Association class 3.0 +/- 0.4, ejection fraction 24 +/- 6%) were retrospectively analyzed for 1 year after implantation of a CRT system. Twenty-five patients received LLT leads and 56 patients received CV leads. Postoperative hospitalization was shorter after CV lead implantation (8 +/- 4 vs 12 +/- 5 days, p <0.01). No significant differences in LV pacing and sensing performance between both approaches were observed after 12 months. Reinterventions were necessary in 7 patients after CV implantation compared with only 1 reintervention (4%) in the LLT group (p = NS). Postoperative chest radiographs revealed an anterior lead position in 11 of 25 patients (44%) in the LLT group versus 3 of 56 patients (5.4%) in the CV group (p = 0.00007). Echocardiographic data demonstrated a significant increase in LV ejection fraction in the CV group (from 26.1 +/- 5.2% to 35.3 +/- 14.3% at 12 months, p <0.001, n = 42) in contrast to the LLT group (from 24.5 +/- 6.2% to 28.5 +/- 7.5% at 12 months, p = NS, n = 16) at 12-month follow-up. Cardiopulmonary exercise testing in 35 patients showed significantly more improvement in peak oxygen consumption after 12 months in the CV group (15.5 +/- 3.1 vs 13.6 +/- 2.6 ml/min/kg at implant, n = 22) compared with the LLT group (12.7 +/- 1.5 vs 11.8 ml/min/kg at implant, n = 13, p = 0.004). At 1-year follow-up the mortality rate was 24% (6 of 25) after LLT lead implantation versus 12.5% (7 of 56) after CV implantation (p = NS). Our data show that the LLT approach for LV lead placement in CRT systems has the advantage of a lower incidence of reinterventions. Hospitalization was longer, increase in functional capacity smaller, and mortality at 1-year follow-up higher, which were potentially related to a more anterior lead position. Therefore, CV leads are preferable to LLT leads.

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PubMed2004

Effects of cardiac resynchronization therapy on myocardial blood flow measured by oxygen-15 water positron emission tomography in idiopathic-dilated cardiomyopathy and left bundle branch block.

Regional and global myocardial blood flow and coronary vascular resistance were determined in patients with idiopathic-dilated cardiomyopathy and left bundle branch block before and during cardiac resynchronization therapy (CRT) using oxygen-15 water positron emission tomography. The investigated parameters did not exhibit regional heterogeneity and were not influenced by CRT. This implies that the beneficial effects of CRT do not require additional oxygen demand or regional reallocation of oxidative metabolism.

Blood Flow Velocity↗

PubMed2004

Aortic valve calcification as a marker for aortic stenosis severity: assessment on 16-MDCT.

OBJECTIVE: The degree of valvular calcification in patients with aortic stenosis was determined with retrospectively ECG-gated 16-MDCT and correlated with the severity of stenosis assessed at cardiac catheterization. SUBJECTS AND METHODS: We conducted a prospective study of 72 patients (38 men and 34 women; mean age +/- SD, 69.5 +/- 8.8 years) with aortic stenosis who underwent 16-MDCT and cardiac catheterization. Aortic valve calcification was assessed using the aortic Agatston score, aortic mass score, and aortic volume score. Severity of aortic stenosis was classified at cardiac catheterization. Aortic valve area and peak-to-peak and mean transvalvular gradients were correlated with the degree of calcification determined on MDCT. RESULTS: All measured aortic valve calcification scores were significantly higher in patients with severe aortic stenosis (n = 46) than in patients with moderate (n = 15) or mild (n = 11, p < 0.001) aortic stenosis. Aortic valve calcification scores were inversely related to aortic valve area (r = -0.67, p < 0.001 for aortic mass score) and correlated significantly with peak-to-peak (r = 0.70, p < 0.001) and mean transvalvular (r = 0.72, p < 0.001) gradients. No correlation between the aortic valve calcification and the total coronary calcium scores was observed. CONCLUSION: Aortic valve calcification assessed on 16-MDCT is associated with severity of aortic stenosis. Thus, aortic valve calcification scores should be calculated routinely in all patients undergoing MDCT for assessment of coronary calcification. High aortic valve calcification scores indicate possibly severe aortic stenosis and should prompt a further functional evaluation.

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PubMed2003

Measurement of cardiac output from a test-bolus injection in multislice computed tomography.

The aim of this study was to assess the feasibility of non-invasive determination of cardiac function from test-bolus data in multislice spiral computed tomography (MSCT). In 25 patients enhancement data gathered from a standardized test-bolus injection were analyzed. The test-bolus examination was performed prior to a retrospectively ECG-gated MSCT of the heart. A time-attenuation curve was obtained in the ascending aorta at the level of the pulmonary arteries. A gamma variate fit was applied to the curve in order to exclude recirculation and get pure first-pass data. Using the known amount of iodine injected, cardiac output (CO), and stroke volume (SV) were determined from integration of the fitted contrast enhancement curve using a reformation of the Stewart-Hamilton equation. Results were compared with CO and SV calculated from the geometric analysis of the retrospectively gated MSCT data using the ARGUS Software (Siemens, Forchheim, Germany). The CO and SV determined from test-bolus analysis and from geometric analysis correlated well with Pearson's correlation coefficients of 0.87 and 0.88, respectively. The standard deviation of the difference between both methods was 0.51 l/min for CO (8.6%) and 11.0 ml for SV (12.3%). Non-invasive quantification of CO seems to be feasible from a standard test-bolus injection. It provides valuable information on cardiac function without additional radiation or application of contrast material.

Cardiac Output↗

PubMed2003

ECG-gated multislice spiral computed tomography to clarify lesion severity in a case of left main stenosis. Multislice spiral computed tomography to clarify lesion severity.

This case report describes the use of retrospectively ECG-gated multislice spiral computed tomography (MSCT) for evaluation of lesion severity in a patient with relevant left main stenosis by visual analysis of the coronary angiogram. For further diagnostic evaluation the patient underwent intravascular ultrasound (IVUS) imaging, which showed a maximal 30% area stenosis, and MSCT, which demonstrated a maximal 48% area stenosis. MSCT was useful in this case to defer cardiac surgery and might be used as a noninvasive alternative to IVUS imaging in case of doubtful lesion severity.

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PubMedDate not supplied

Multislice spiral computed tomography of the heart: technique, current applications, and perspective.

Multislice spiral computed tomography (MSCT) is a rapidly evolving, noninvasive technique for cardiac imaging. Knowledge of the principle of electrocardiogram-gated MSCT and its limitations in clinical routine are needed to optimize image quality. Therefore, the basic technical principle including essentials of image postprocessing is described. Cardiac MSCT imaging was initially focused on coronary calcium scoring, MSCT coronary angiography, and analysis of left ventricular function. Recent studies also evaluated the ability of cardiac MSCT to visualize myocardial infarction and assess valvular morphology. In combination with experimental approaches toward the assessment of aortic valve function and myocardial viability, cardiac MSCT holds the potential for a comprehensive examination of the heart using one single examination technique.

Calcinosis↗