Karl-Christian Koch

Philipps University of Marburg, Marburg, Hesse, Germany

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Publications (23)120.62 Total impact

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    ABSTRACT: Gated myocardial perfusion SPECT allows calculation of end-diastolic and end-systolic volumes (EDV and ESV, respectively) and left ventricular ejection fraction (LVEF). The quantification algorithms QGS (quantitative gated SPECT), 4D-MSPECT, and CARE heart show a good correlation with cardiac MRI. Nevertheless, differences in contour finding suggest algorithm-specific effects if heart axes vary. The effect of tilting heart axes on gated SPECT was quantified as a possible source of error. Sixty men underwent gated SPECT (450 MBq of (99m)Tc-tetrofosmin or sestamibi, 8 gates/cycle). After correct reorientation (R(0)), datasets were tilted by 5 degrees , 10 degrees , 15 degrees , 20 degrees , 30 degrees , and 45 degrees along both long axes (R(5), R(10), R(15), R(20), R(30), and R(45), respectively). EDV, ESV, and LVEF were calculated using QGS, 4D-MSPECT, and CARE heart. Because a 15 degrees tilt could be a maximum possible misreorientation in routine, R(0) and R(15) results were analyzed in detail. Absolute-difference values between results of tilted and correctly reoriented datasets were calculated for all tilts and algorithms. QGS and CARE heart succeeded for R(0) and R(15) in all cases, whereas 4D-MSPECT failed to find the basal plane in 1 case (patient B). R(2) values between paired R(15)/R(0) results were 0.992 (QGS), 0.796 (4D-MSPECT; R(2) = 0.919 in n = 59 after exclusion of the failed case), and 0.916 (CARE heart) for EDV; 0.994 (QGS), 0.852 (4D-MSPECT; R(2) = 0.906 in n = 59), and 0.899 (CARE heart) for ESV; and 0.988 (QGS), 0.814 (4D-MSPECT; R(2) = 0.810 in n = 59), and 0.746 (CARE heart) for LVEF. Concerning all levels of misreorientation, 1 patient was excluded for all algorithms because of multiple problems in contour finding; additionally for 4D-MSPECT patient B was excluded. In the 45 degrees group, QGS succeeded in 58 of 59 cases, 4D-MSPECT in 58 of 58, and CARE heart in 33 of 59. Mean absolute differences for EDV ranged from 5.1 +/- 4.1 to 12.8 +/- 10.5 mL for QGS, from 6.7 +/- 6.3 to 34.2 +/- 20.7 mL for 4D-MSPECT, and from 5.4 +/- 5.6 to 25.2 +/- 16.1 mL for CARE heart (tilts between 5 degrees and 45 degrees ). Mean absolute differences for ESV ranged from 4.1 +/- 3.7 to 8.0 +/- 9.4 mL for QGS, from 5.6 +/- 8.0 to 10.0 +/- 10.5 mL for 4D-MSPECT, and from 5.4 +/- 5.6 to 25.5 +/- 16.1 mL for CARE heart. Mean absolute differences for LVEF ranged from 1.1% +/- 1.0% to 2.2% +/- 1.8% for QGS, from 4.0% +/- 3.5% to 8.0% +/- 7.1% for 4D-MSPECT, and from 3.4% +/- 2.9% to 9.2% +/- 6.0% for CARE heart. Despite tilted heart axes, QGS showed stable results even when using tilts up to 45 degrees . 4D-MSPECT and CARE heart results varied with reorientation of the heart axis, implying that published validation results apply to correctly reoriented data only.
    Journal of Nuclear Medicine 10/2008; 49(10):1636-42. · 5.77 Impact Factor
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    ABSTRACT: Current treatment of advanced chronic heart failure comprises pharmacologic approaches, multidisciplinary management strategies and device therapy. We sought to compare the outcome after cardiac synchronization therapy (CRT) with the outcome after heart transplantation within a contemporary heart failure management program. In a cohort study, survival and quality of life were assessed in 105 patients who had received CRT (53% with defibrillator) for severe heart failure and in 112 heart transplant recipients attending a heart failure clinic at a tertiary hospital. For assessment of health-related quality of life the Medical Outcome Short Form 36 (SF-36) was applied to the survivors. A propensity score for receiving transplantation vs CRT was developed using logistic regression and was incorporated into statistical models. Severity of heart failure before heart transplantation or CRT was similar. Survival was not different between device recipients and transplant recipients by Kaplan-Meier analysis. Cox regression analysis with time-dependent covariates revealed a significant interaction between treatment and time, which favored transplantation late after intervention. There were no significant differences in 7 of 8 subjective measures of health-related quality of life. The score for physical functioning was higher in the transplantation group; this difference remained of borderline significance after multivariate adjustment. Contemporary management of patients with advanced heart failure including CRT leads to improved survival and quality of life and diminishes the difference in these outcomes between conservative management and heart transplantation within the time-frame studied. Patient selection for heart transplantation requires consideration of these results.
    The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 08/2008; 27(7):746-52. · 3.54 Impact Factor
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    ABSTRACT: There is proven evidence for the importance of myocardial perfusion-single-photon emission computed tomography (SPECT) with computerised determination of summed stress and rest scores (SSS/SRS) for the diagnosis of coronary artery disease (CAD). SSS and SRS can thereby be calculated semi-quantitatively using a 20-segment model by comparing tracer-uptake with values from normal databases (NDB). Four severity-degrees for SSS and SRS are normally used: <4, 4-8, 9-13, and > or =14. Manufacturers' NDBs (M-NDBs) often do not fit the institutional (I) settings. Therefore, this study compared SSS and SRS obtained with the algorithms Quantitative Perfusion SPECT (QPS) and 4D-MSPECT using M-NDB and I-NDB. I-NDBs were obtained using QPS and 4D-MSPECT from exercise stress data (450 MBq (99m)Tc-tetrofosmin, triple-head-camera, 30 s/view, 20 views/head) from 36 men with a low post-stress test CAD probability and visually normal SPECT findings. Patient group was 60 men showing the entire CAD-spectrum referred for routine perfusion-SPECT. Stress/rest results of automatic quantification of the 60 patients were compared to M-NDB and I-NDB. After reclassifying SSS/SRS into the four severity degrees, kappa values were calculated to objectify agreement. Mean values (vs M-NDB) were 9.4 +/- 10.3 (SSS) and 5.8 +/- 9.7 (SRS) for QPS and 8.2 +/- 8.7 (SSS) and 6.2 +/- 7.8 (SRS) for 4D-MSPECT. Thirty seven of sixty SSS classifications (kappa = 0.462) and 40/60 SRS classifications (kappa = 0.457) agreed. Compared to I-NDB, mean values were 10.2 +/- 11.6 (SSS) and 6.5 +/- 10.4 (SRS) for QPS and 9.2 +/- 9.3 (SSS) and 7.2 +/- 8.6 (SRS) for 4D-MSPECT. Forty four of sixty patients agreed in SSS and SRS (kappa = 0.621 resp. 0.58). Considerable differences between SSS/SRS obtained with QPS and 4D-MSPECT were found when using M-NDB. Even using identical patients and identical I-NDB, the algorithms still gave substantial different results.
    European journal of nuclear medicine and molecular imaging 02/2008; 35(2):311-8. · 5.11 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the costs and health status outcomes of intensive care unit (ICU) admission in patients who present after sudden cardiac arrest with in-hospital or out-of-hospital cardiopulmonary resuscitation. Five-year survival, health-related quality of life (Medical Outcome Survey Short Form-36 questionnaire, SF-36), ICU costs, hospital costs and post-hospital health care costs per survivor, costs per life year gained, and costs per quality-adjusted life year gained of patients admitted to a single ICU were assessed. One hundred ten of 354 patients (31%) were alive 5 years after hospital discharge. The mean health status index of 5-year survivors was 0.77 (95% confidence interval 0.70 to 0.85). Women rated their health-related quality of life significantly better than men did (0.87 versus 0.74; P < 0.05). Costs per hospital discharge survivor were 49,952 euro. Including the costs of post-hospital discharge health care incurred during their remaining life span, the total costs per life year gained were 10,107 euro. Considering 5-year survivors only, the costs per life year gained were calculated as 9,816 euro or 14,487 euro per quality-adjusted life year gained. Including seven patients with severe neurological sequelae, costs per life year gained in 5-year survivors increased by 18% to 11,566 euro. Patients who leave the hospital following cardiac arrest without severe neurological disabilities may expect a reasonable quality of life compared with age- and gender-matched controls. Quality-adjusted costs for this patient group appear to be within ranges considered reasonable for other groups of patients.
    Critical care (London, England) 01/2008; 12(4):R92. · 4.72 Impact Factor
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    ABSTRACT: Myocardial regeneration after myocardial infarction can occur via stem cell recruitment. Stromal cell-derived factor 1alpha (SDF-1alpha) has been shown to be critical for stem cell homing to injured tissue. Myocardial infarction was induced in pigs via microembolization of the distal left anterior descending artery. Two weeks after myocardial infarction animals underwent catheter-based transendocardial injection of SDF-1alpha into the periinfarct myocardium (18 injections, 5 ìg per injection) (n = 12) or sham-intervention (n = 8). Tc99m sestamibi single-photon emission computed tomography (SPECT) and electromechanical mapping (EMM) of the left ventricle were performed two and seven weeks after myocardial infarction. Infarct size by tetrazolium staining was similar in both groups (8.9 +/-1.2% of left ventricle vs. 8.9 +/- 2.6%). Vessel density in the periinfarct area was significantly higher in SDF-1alpha treated animals than in controls (349 +/- 17/mm2 vs. 276 +/- 21/mm2, p < 0.05). Myocardial perfusion (SPECT) did not change in either group. Ejection fraction and stroke volume (EMM) decreased in SDF-1alpha animals and increased in controls (difference between groups p = 0.05 for ejection fraction and p < 0.05 for stroke volume). Linear local shortening (EMM) did not change in controls (11.4 +/- 1.3% to 11.5 +/- 0.5%) but decreased significantly in SDF-1alpha treated animals (12.1 +/- 0.9% to 8.4 +/- 0.9%, p < 0.05, p < 0.05 for difference between groups). SDF-1 delivery was associated with a substantial loss of collagen in the periinfarct area (32+/-5% vs. 61+/-6% in control animals, p < 0.005). A strategy to augment stem cell homing by catheter-based transendocardial delivery of SDF-1alpha in experimental myocardial infarction increases periinfarct vessel density, fails to improve myocardial perfusion, is associated with loss of collagen in the periinfarct area and impairs left ventricular function.
    Archiv für Kreislaufforschung 01/2006; 101(1):69-77. · 5.90 Impact Factor
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    ABSTRACT: Fractional flow reserve (FFR) is a valid surrogate for hemodynamic significance in stenotic native coronary arteries. The aim of this study was to examine the value of FFR compared to stress perfusion myocardial scintigraphy (SPMS) in patients with coronary stent restenosis. We studied 42 patients, aged 62+/-10 years, with stent restenosis 5.3+/-1.6 months after coronary stent implantation. All patients had a single coronary lesion of intermediate severity (diameter stenosis 40-70%). FFR measurement, SPMS, and quantitative angiography of the stent stenosis were performed in all patients. The mean percentage in stent diameter stenosis was 53+/-9%. FFR was 0.77+/-0.15. In 20 patients FFR was below 0.75. Nineteen patients had reversible perfusion defects in SPMS. FFR showed good diagnostic accuracy for the detection of reversible perfusion defects in SPMS (AUROC 0.86, 95% CI 0.74-0.98). The percentage of agreement of SPMS and FFR was 88%, with the best cutoff value of 0.75 for FFR. A FFR value of 0.75 is not only valid for diagnosing significant native coronary stenosis, but also for stent restenosis. Thus, FFR measurement should be taken into account when making decisions regarding patients with stent restenosis.
    European Journal of Internal Medicine 11/2005; 16(6):429-31. · 2.30 Impact Factor
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    ABSTRACT: Fractional flow reserve (FFR) is a valid surrogate for hemodynamic significance in stenotic native coronary arteries, but its validity in patients with coronary stent restenosis is unknown. Prospective. University hospital. We studied 42 patients (mean age +/- 1 SD, 62 +/- 10 years) with stent restenosis and 57 patients (mean age, 61 +/- 12 years) with a native coronary lesion. All patients demonstrated a single coronary lesion of intermediate severity (stenosis diameter, 40 to 70%). Determination of FFR and quantitative angiography of the stenosis were performed. Stenosis diameter was comparable in both groups (native, 52 +/- 11%; stent, 52 +/- 9%; not significant [NS]). FFR was lower in stent restenosis (0.77 +/- 0.15 vs 0.82 +/- 0.12, p < 0.05) and more often pathologic with an FFR < 0.75 (48% vs 26%, p < 0.05) compared to native coronary stenosis. However, the area under the receiver operating characteristic curve for native stenosis was 0.82 (95% confidence interval [CI], 0.71 to 0.94) and for stent restenosis was 0.84 (95% CI, 0.71 to 0.97; NS). In patients with an FFR > 0.75, there was no adverse coronary event that was related to the stented lesion in the subsequent 6 months. The threshold of stenosis diameter of coronary lesions for pathologic FFR measurement (FFR < 0.75) is similar for stent restenosis and native coronary stenosis. Thus, FFR measurement seems to be applicable for decision making in patients with stent restenosis.
    Chest 10/2005; 128(3):1645-9. · 7.13 Impact Factor
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    ABSTRACT: The goal of this study was to validate the accuracy of the Emory Cardiac Tool Box (ECTB) in assessing left ventricular end-diastolic or end-systolic volume (EDV, ESV) and ejection fraction (LVEF) from gated (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) SPECT using cardiac MRI (cMRI) as a reference. Furthermore, software-specific characteristics of ECTB were analyzed in comparison with 4D-MSPECT and Quantitative Gated SPECT (QGS) results (all relative to cMRI). Seventy patients with suspected or known coronary artery disease were examined using gated (99m)Tc-MIBI SPECT (8 gates/cardiac cycle) 60 min after tracer injection at rest. EDV, ESV, and LVEF were calculated from gated (99m)Tc-MIBI SPECT using ECTB, 4D-MSPECT, and QGS. Directly before or after gated SPECT, cMRI (20 gates/cardiac cycle) was performed as a reference. EDV, ESV, and LVEF were calculated using Simpson's rule. Correlation between results of gated (99m)Tc-MIBI SPECT and cMRI was high for EDV (R = 0.90 [ECTB], R = 0.88 [4D-MSPECT], R = 0.92 [QGS]), ESV (R = 0.94 [ECTB], R = 0.96 [4D-MSPECT], R = 0.96 [QGS]), and LVEF (R = 0.85 [ECTB], R = 0.87 [4D-MSPECT], R = 0.89 [QGS]). EDV (ECTB) did not differ significantly from cMRI, whereas 4D-MSPECT and QGS underestimated EDV significantly compared with cMRI (mean +/- SD: 131 +/- 43 mL [ECTB], 127 +/- 42 mL [4D-MSPECT], 120 +/- 38 mL [QGS], 137 +/- 36 mL [cMRI]). For ESV, only ECTB yielded values that were significantly lower than cMRI. For LVEF, ECTB and 4D-MSPECT values did not differ significantly from cMRI, whereas QGS values were significantly lower than cMRI (mean +/- SD: 62.7% +/- 13.7% [ECTB], 59.0% +/- 12.7% [4DM-SPECT], 53.2% +/- 11.5% [QGS], 60.6% +/- 13.9% [cMRI]). EDV, ESV, and LVEF as determined by ECTB, 4D-MSPECT, and QGS from gated (99m)Tc-MIBI SPECT agree over a wide range of clinically relevant values with cMRI. Nevertheless, any algorithm-inherent over- or underestimation of volumes and LVEF should be accounted for and an interchangeable use of different software packages should be avoided.
    Journal of Nuclear Medicine 09/2005; 46(8):1256-63. · 5.77 Impact Factor
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    ABSTRACT: To assess long-term survival, health-related quality of life, and associated costs 5 yrs after discharge from a medical intensive care unit. Prospective cohort study. Medical intensive care unit of a German university hospital. Three hundred and three consecutive patients with predominantly cardiovascular and pulmonary disorders admitted between November 1997 and February 1998 with an intensive care unit length of stay >24 hrs. None. Demographic data, Simplified Acute Physiology Score II, Sequential Organ Failure Assessment, simplified Therapeutic Intervention Scoring System, and individual intensive care unit and hospital costs were prospectively recorded. Primary outcomes included 5-yr survival, functional status, health-related quality of life (Medical Outcome Short Form, SF-36), effective costs per survivor, and costs per life year and per quality-adjusted life year gained. Of 303 patients, 44 (14.5%) died in the hospital. Among the remaining 259 patients, 190 (73%) survived the 5-yr follow up and 173 patients (91%) completed the questionnaire. Baseline demographics including gender, age, Simplified Acute Physiology Score II, Sequential Organ Failure Assessment, simplified Therapeutic Intervention Scoring System, and admission diagnosis were similar between hospital and long-term survivors (p > .05 for all). The health status index of those patients surviving the 5-yr follow-up was 0.88, independent of patients' severity of illness. The average effective costs per survivor were 8.827 for intensive care unit costs and 14.130 for intensive care unit and hospital costs. Mean costs per life year and per quality-adjusted life year gained amounted to 19.330 and 21.922 , respectively. Increasing severity of illness was associated with higher costs. Considering the severity of illness and the patients' outcome, the costs associated with both life year and quality-adjusted life year gained were within generally accepted limits for other potentially life-saving treatments.
    Critical Care Medicine 03/2005; 33(3):547-55. · 6.12 Impact Factor
  • Circulation 02/2005; 111(3):e23. · 15.20 Impact Factor
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    ABSTRACT: Gated myocardial perfusion SPECT allows assessment of left ventricular end-diastolic volume (EDV), left ventricular end-systolic volume (ESV), left ventricular stroke volume (SV), and left ventricular ejection fraction (LVEF). Acquiring images with the patient both prone and supine is an approved method of identifying and reducing artifacts. Yet prone positioning alters physiologic conditions. This study investigated how prone versus supine patient positioning during gated SPECT affects EDV, ESV, SV, LVEF, and heart rate. Forty-eight patients scheduled for routine myocardial perfusion imaging were examined with gated (99m)Tc-sestamibi SPECT (at rest) while positioned prone and supine (consecutively, in random order). All parameters for both acquisitions were calculated using the commercially available QGS algorithm. Whereas EDV and SV were significantly lower (P < 0.0004) for prone acquisitions (EDV, 110.5 +/- 39.1 mL; SV, 55.9 +/- 13.3 mL) than for supine acquisitions (EDV, 116.9 +/- 36.2 mL; SV, 61.0 +/- 14.5 mL), ESV and LVEF did not differ significantly. Heart rate was significantly higher (P < 0.0001) during prone acquisitions (69.1 +/- 10.5 min(-1)) than during supine acquisitions (66.5 +/- 10.0 min(-1)). The observed position-dependent effect on EDV, SV, and heart rate might be explained by decreased arterial filling and increased sympathetic nerve activity. Hence, supine reference data should not be used to classify the results of prone acquisitions.
    Journal of Nuclear Medicine 01/2005; 45(12):2016-20. · 5.77 Impact Factor
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    ABSTRACT: Endocardial electromechanical mapping (EEM) has been proposed as a method for myocardial viability assessment. However, the impact of EEM data on clinical outcome has not been studied before. We sought to assess the prognostic value of EEM in patients with left ventricular (LV) dysfunction undergoing percutaneous coronary intervention (PCI). Seventy-five patients with coronary artery disease and LV dysfunction (angiographic LV ejection fraction [EF] 49 +/- 15%) underwent LV EEM for myocardial viability assessment before coronary revascularization. EEM parameters included mean unipolar electrographic amplitude, mean local shortening, LV volumes, LVEF, number of regions with electrographic amplitudes <7.5 mV, number of electromechanical mismatch, and match regions. Cardiac death, nonfatal myocardial infarction, nonfatal stroke, and acute heart failure requiring hospitalization were defined as clinical events. During a follow-up of 3.6 +/- 1.8 years, 20 clinical events occurred. Event-free survival after coronary revascularization was significantly better in patients with a mean unipolar electrographic amplitude of >/=9.5 mV than in patients with a mean unipolar electrographic amplitude of <9.5 mV (88% vs 57%; p <0.005). Cox regression analysis revealed angiographic LVEF, mean electrographic amplitude, number of regions with electrographic amplitudes <7.5 mV, number of electromechanical match regions, and EEM EF as univariate predictors of clinical events. In a multivariate analysis, angiographic LVEF <40% (hazard ratio 4.78, p <0.005) and mean electrographic amplitude <9.5 mV (hazard ratio 2.92, p <0.05) were independent predictors of clinical events. Thus, EEM provides prognostic information in patients with LV dysfunction undergoing coronary revascularization.
    The American Journal of Cardiology 12/2004; 94(9):1129-33. · 3.21 Impact Factor
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    ABSTRACT: The main aim of this study was to validate the accuracy of 4D-MSPECT in the assessment of left ventricular (LV) end-diastolic/end-systolic volumes (EDV, ESV) and ejection fraction (LVEF) from gated technetium-99m methoxyisobutylisonitrile single-photon emission tomography ((99m)Tc-MIBI SPET), using cardiac magnetic resonance imaging (cMRI) as the reference method. By further comparing 4D-MSPECT and QGS with cMRI, the software-specific characteristics were analysed to elucidate clinical applicability. Fifty-four patients with suspected or proven coronary artery disease (CAD) were examined with gated (99m)Tc-MIBI SPET (8 gates/cardiac cycle) about 60 min after tracer injection at rest. LV EDV, ESV and LVEF were calculated from gated (99m)Tc-MIBI SPET using 4D-MSPECT and QGS. On the same day, cMRI (20 gates/cardiac cycle) was performed, with LV EDV, ESV and LVEF calculated using Simpson's rule. Both algorithms worked with all data sets. Correlation between the results of gated (99m)Tc-MIBI SPET and cMRI was high for EDV [ R=0.89 (4D-MSPECT), R=0.92 (QGS)], ESV [ R=0.96 (4D-MSPECT), R=0.96 (QGS)] and LVEF [ R=0.89 (4D-MSPECT), R=0.90 (QGS)]. In contrast to ESV, EDV was significantly underestimated by 4D-MSPECT and QGS compared to cMRI [130+/-45 ml (4D-MSPECT), 122+/-41 ml (QGS), 139+/-36 ml (cMRI)]. For LVEF, 4D-MSPECT and cMRI revealed no significant differences, whereas QGS yielded significantly lower values than cMRI [57.5%+/-13.7% (4D-MSPECT), 52.2%+/-12.4% (QGS), 60.0%+/-15.8% (cMRI)]. In conclusion, agreement between gated (99m)Tc-MIBI SPET and cMRI is good across a wide range of clinically relevant LV volume and LVEF values assessed by 4D-MSPECT and QGS. However, algorithm-varying underestimation of LVEF should be accounted for in the clinical context and limits interchangeable use of software.
    European journal of nuclear medicine and molecular imaging 05/2004; 31(4):482-90. · 5.11 Impact Factor
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    ABSTRACT: Ectopic beats originating from sleeves of atrial tissue within the pulmonary veins (PVs) can induce and sustain paroxysmal atrial fibrillation (AF). Left atrial stretch and dilatation favors the development of atrial ectopy and AF. Similarly, PV dilatation, if present, might trigger PV ectopy in patients with AF. This study was designed to evaluate whether PV dilatation is present in patients with nonfocal AF and whether the PV diameter correlates to the left atrial diameter (LAD). The diameters of the right superior (RSPV) and left superior PV (LSPV) were measured at the ostium and at a depth of 1 cm in 170 patients (AF, n = 75; sinus rhythm [SR], n = 95) using transesophageal echocardiography. The LAD was determined by transthoracic echocardiography. The diameters of the PVs were significantly larger in patients with AF than in patients with SR (LSPV(ostium): AF 13.6 +/- 3.5 mm vs SR 10.6 +/- 2.7 mm, P < 0.001; LSVP(1cm): AF 12.5 +/- 2.9 mm vs SR 10.2 +/- 2.5 mm, P < 0.001; RSPV(ostium): AF 13.9 +/- 3.5 mm vs SR 11.7 +/- 2.9 mm, P < 0.001; RSVP(1cm): AF 12.8 +/- 2.8 mm vs SR 10.6 +/- 2.6 mm, P < 0.05). Similarly, LAD was larger in patients with AF (44.7 +/- 7.7 mm) as compared to patients with SR (38.8 +/- 6.8 mm, P < 0.001). Neither for the SR nor the AF group did the PV size correlate to the LAD. AF is associated with a significant enlargement of the RSPV, LSPV, and LAD. There is no correlation between LAD and PV diameters. This raises the question whether PV dilatation in patients with AF is a cause or a consequence of AF and whether it may contribute to the development and perpetuation of AF.
    Pacing and Clinical Electrophysiology 06/2003; 26(6):1371-8. · 1.75 Impact Factor
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    ABSTRACT: Objectives We investigated whether cardiac resynchronization therapy (CRT) affects myocardial glucose metabolism and perfusion in dilated cardiomyopathy (DCM) and left bundle branch block (LBBB).Background Patients with DCM and LBBB present with asynchronous left ventricular (LV) activation, leading to reduced septal glucose metabolism. Cardiac resynchronization therapy recoordinates LV activation, but its effects on myocardial glucose metabolism and perfusion remain unknown.Methods In 15 patients (10 females; 61 ± 13 years) with DCM and LBBB (QRS width 165 ± 15 ms), gated 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and technetium-99m (99mTc)-sestamibi single-photon emission computed tomography were performed before and after two weeks of CRT. Uptake of FDG and 99mTc-sestamibi was determined in four LV wall areas. Ejection fraction and volumes were calculated from gated PET.ResultsBaseline FDG uptake was heterogeneous (p < 0.0001), with lowest uptake in the septal region (56 ± 12%) and highest uptake in the lateral region (89 ± 6%). During CRT, septal and anterior increases (p < 0.01) and lateral decreases (p < 0.01) resulted in homogeneously distributed glucose metabolism. Baseline heterogeneity (p < 0.0001) in 99mTc-sestamibi uptake was modest (lowest septal 65 ± 10%; maximum lateral 84 ± 5%) and also reduced with CRT, although some heterogeneity (p < 0.05) remained. The septal-to-lateral ratio increased with CRT for FDG (0.62 ± 0.12 to 0.91 ± 0.26, p < 0.001) and 99mTc-sestamibi uptake (0.77 ± 0.13 to 0.85 ± 0.16, p < 0.01). The LV end-diastolic and end-systolic volumes decreased from 293 ± 160 to 272 ± 158 ml (p < 0.05) and from 244 ± 164 to 220 ± 160 ml (p < 0.01), respectively. Ejection fraction increased from 22 ± 12% to 25 ± 13% (p < 0.01).Conclusions Glucose metabolism is reduced more than perfusion in the septal compared with LV lateral wall in patients with DCM and LBBB. Cardiac resynchronization therapy restores homogeneous myocardial glucose metabolism with less influence on perfusion.
    Journal of the American College of Cardiology 05/2003; 41(9):1523–1528. · 14.09 Impact Factor
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    ABSTRACT: We investigated whether cardiac resynchronization therapy (CRT) affects myocardial glucose metabolism and perfusion in dilated cardiomyopathy (DCM) and left bundle branch block (LBBB). Patients with DCM and LBBB present with asynchronous left ventricular (LV) activation, leading to reduced septal glucose metabolism. Cardiac resynchronization therapy recoordinates LV activation, but its effects on myocardial glucose metabolism and perfusion remain unknown. In 15 patients (10 females; 61 +/- 13 years) with DCM and LBBB (QRS width 165 +/- 15 ms), gated (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and technetium-99m ((99m)Tc)-sestamibi single-photon emission computed tomography were performed before and after two weeks of CRT. Uptake of FDG and (99m)Tc-sestamibi was determined in four LV wall areas. Ejection fraction and volumes were calculated from gated PET. Baseline FDG uptake was heterogeneous (p < 0.0001), with lowest uptake in the septal region (56 +/- 12%) and highest uptake in the lateral region (89 +/- 6%). During CRT, septal and anterior increases (p < 0.01) and lateral decreases (p < 0.01) resulted in homogeneously distributed glucose metabolism. Baseline heterogeneity (p < 0.0001) in (99m)Tc-sestamibi uptake was modest (lowest septal 65 +/- 10%; maximum lateral 84 +/- 5%) and also reduced with CRT, although some heterogeneity (p < 0.05) remained. The septal-to-lateral ratio increased with CRT for FDG (0.62 +/- 0.12 to 0.91 +/- 0.26, p < 0.001) and (99m)Tc-sestamibi uptake (0.77 +/- 0.13 to 0.85 +/- 0.16, p < 0.01). The LV end-diastolic and end-systolic volumes decreased from 293 +/- 160 to 272 +/- 158 ml (p < 0.05) and from 244 +/- 164 to 220 +/- 160 ml (p < 0.01), respectively. Ejection fraction increased from 22 +/- 12% to 25 +/- 13% (p < 0.01). Glucose metabolism is reduced more than perfusion in the septal compared with LV lateral wall in patients with DCM and LBBB. Cardiac resynchronization therapy restores homogeneous myocardial glucose metabolism with less influence on perfusion.
    Journal of the American College of Cardiology 05/2003; 41(9):1523-8. · 14.09 Impact Factor
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    ABSTRACT: The "Therapeutic Intervention Scoring System" (TISS) and the simplified version TISS-28 obtain the therapeutic workload in the critically ill and may be used for outcome prediction. The feasibility and applicability regarding cost analysis and outcome prediction of TISS and TISS-28 have been assessed in 303 consecutive medical patients staying longer than 24 h in the intensive care unit (ICU). The mean age of the enrolled patients was 62 +/- 12 years, 216 (71%) patients were male, length of ICU stay 3.7 +/- 4.7 days, and SAPS II (Simplified Acute Physiology Score) 26 +/- 13 points. The overall mortality was 44 patients (14.5%) with 25 patients (8.3%) dying while on the ICU. The data collection process for TISS took significantly longer than for TISS-28. On the day of admission, the correlation of TISS and TISS-28 was excellent (r(2) = 0.91; p < 0.001). The discriminatory power as assessed by the area under the receiver operating characteristic (ROC) curve was satisfactory for TISS (0.79 +/- 0.04), TISS-28 (0.76 +/- 0.04), and SAPS II (0.77 +/- 0.04) with regard to outcome prediction. Patient-specific costs per TISS-28 point amounted to 36 euros.--and were significantly higher than the 25 euros.--calculated per TISS point. Staff costs (42%) were the most prominent cost-generating factor, and patient-specific costs contributed two thirds to the total ICU costs. There was no association of severity of illness or number of organ failure and costs. Only the length of ICU stay correlated strongly with the costs of the individual patients during the ICU stay (r(2) = 0.79; p < 0.001). The faster data collection process as well as the uniformity of the system are strong clinical and scientific advantages of the TISS-28. In addition, TISS-28 is capable of calculating individual costs in an acceptable time frame. Therefore TISS-28 serves as a valuable tool for quality assurance and cost analysis purposes in the medical ICU.
    Medizinische Klinik 03/2003; 98(3):123-32. · 0.34 Impact Factor
  • The American Journal of Cardiology 03/2003; 91(4):469-72. · 3.21 Impact Factor
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    ABSTRACT: There is controversy about the role of decreased resting blood flow as the pathophysiologic correlate of hibernating myocardium. The aim of this study was an absolute quantification of volumetric myocardial blood flow (MBFvol) in dysfunctional myocardium with different viability conditions as defined by fluorine 18 deoxyglucose (FDG) positron emission tomography (PET) while taking into consideration the functional recovery after revascularization. The impact of MBFvol in the diagnosis of functional recovery was also investigated. Forty-two patients with severe coronary artery disease and dysfunctional myocardium underwent resting oxygen 15 water PET, as well as FDG PET and technetium 99m tetrofosmin single photon emission computed tomography, all attenuation-corrected. Relative FDG and Tc-99m tetrofosmin uptake (normalized to the segment with 100% Tc-99m tetrofosmin uptake), as well as MBFvol (myocardial blood flow multiplied by the water-perfusable tissue fraction to account for the flow to the entire segment volume), were determined in 18 myocardial segments per patient. Viability in dysfunctional segments (estimated by ventriculography) with reduced Tc-99m tetrofosmin uptake of 70% or lower was classified as viable (FDG >70%, mismatch) or nonviable (FDG < or =70%, match). Fifteen patients underwent revascularization and were followed up. Mismatch segments with improved function were classified as hibernating myocardium. Mean MBFvol in viable myocardium was slightly reduced (0.60 +/- 0.02 mL x min(-1) x mL(-1)) compared with that in normokinetic myocardium (0.64 +/- 0.01 mL x min(-1) x mL(-1)) (P = .036) and was significantly higher than in nonviable myocardium (0.36 +/- 0.01 mL x min(-1) x mL(-1)) (P < .001). Receiver operating characteristic analysis confirmed an FDG uptake greater than 70% as the optimal threshold to predict functional recovery (diagnostic accuracy [ACC], 76%). MBFvol in hibernating myocardium (0.62 +/- 0.04 mL x min(-1) x mL(-1)) was not significantly reduced compared with that in normokinetic myocardium (0.66 +/- 0.02 mL x min(-1) x mL(-1)) and was significantly higher than in persistently dysfunctional myocardium (0.51 +/- 0.04 mL x min(-1) x mL(-1)) (P < .05). The ACC of MBFvol greater than 0.40 mL x min(-1) x mL(-1) as the threshold to predict functional recovery was 61% but did not improve the accuracy of FDG PET by itself. In patients with severe coronary artery disease and dysfunctional myocardium, MBFvol as determined with O-15 water differs significantly between viable and nonviable myocardium as determined by FDG PET and is not significantly reduced in hibernating compared with normokinetic myocardium. Therefore chronically reduced resting blood flow appears unlikely to be the pathophysiologic correlate of the functional state of hibernation. However, MBFvol does not improve the ACC of FDG PET by itself.
    Journal of Nuclear Cardiology 01/2003; 10(1):34-45. · 2.85 Impact Factor
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    ABSTRACT: Myocardial perfusion imaging with (99m)Tc-tetrofosmin is based on the assumption of a linear correlation between myocardial blood flow (MBF) and tracer uptake. However, it is known that (99m)Tc-tetrofosmin uptake is directly related to energy-dependent transport processes, such as Na(+)/H(+) ion channel activity, as well as cellular and mitochondrial membrane potentials. Therefore, cellular alterations that affect these energy-dependent transport processes ought to influence (99m)Tc-tetrofosmin uptake independently of blood flow. Because metabolism ((18)F-FDG)-perfusion ((99m)Tc-tetrofosmin) mismatch myocardium (MPMM) reflects impaired but viable myocardium showing cellular alterations, MPMM was chosen to quantify the blood flow-independent effect of cellular alterations on (99m)Tc-tetrofosmin uptake. Therefore, we compared microsphere-equivalent MBF (MBF_micr; (15)O-water PET) and (99m)Tc-tetrofosmin uptake in MPMM and in "normal" myocardium. Forty-two patients with severe coronary artery disease, referred for myocardial viability diagnostics, were examined using (18)F-FDG PET and (99m)Tc-tetrofosmin perfusion SPECT. Relative (18)F-FDG and (99m)Tc-tetrofosmin uptake values were calculated using 18 segments per patient. Normal myocardium and MPMM myocardium were classified using a previously validated (99m)Tc-tetrofosmin SPECT/(18)F-FDG PET score. In addition, (15)O-water PET was performed to assess kinetic-modeled MBF (MBF_kin), the water-perfusable tissue fraction (PTF), and the resulting MBF_micr (MBF_kin x PTF), which is comparable to tracer uptake values. (99m)Tc-tetrofosmin uptake and MBF_micr values were calculated for all normal and MPMM segments and averaged within their respective classifications. Mean relative (99m)Tc-tetrofosmin uptake was 86% +/- 1% in normal myocardium and 56% +/- 1% in MPMM, showing a significant difference (P < 0.001), as was expected from the classification. Contrary to these findings, mean MBF_micr in MPMM myocardium was 0.60 +/- 0.03 mL x min(-1) x mL(-1), which did not significantly differ from normal myocardium (0.64 +/- 0.01 mL x min(-1) x mL(-1)). All values are given as mean +/- SEM. Differences between reduced (99m)Tc-tetrofosmin uptake and the unchanged MBF_micr in MPMM myocardium suggest that the pathophysiologic basis of MPMM is not a blood flow reduction but cellular alterations that affect uptake and retention of (99m)Tc-tetrofosmin independently of blood flow. Therefore, it seems that perfusion deficits in MPMM myocardium are greatly overestimated by (99m)Tc-tetrofosmin and that it tends to give false-positive findings.
    Journal of Nuclear Medicine 01/2003; 44(1):33-9. · 5.77 Impact Factor

Publication Stats

335 Citations
120.62 Total Impact Points

Institutions

  • 2008
    • Philipps University of Marburg
      Marburg, Hesse, Germany
  • 2002–2008
    • RWTH Aachen University
      • • Department of Nuclear Medicine
      • • Institute of Medical Statistics
      Aachen, North Rhine-Westphalia, Germany
    • University Hospital RWTH Aachen
      • Department of Neurology
      Aachen, North Rhine-Westphalia, Germany