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C Grädel

Publications and source records attributed to C Grädel.

5 recordsLinked to original sources
PubMed2001

Comparison of 99mTc-sestamibi lung/heart ratio, transient ischaemic dilation and perfusion defect size for the identification of severe and extensive coronary artery disease.

The ability to identify patients with severe coronary artery disease (CAD) by analysis of perfusion defects is limited. The lung/heart ratio (LHR) and transient ischaemic dilatation (TID) have been used for this purpose in thallium-201 scintigraphy. The value of these parameters in technetium-99m sestamibi single-photon emission tomography (SPET) imaging is controversial. In this study, therefore, we determined TID and LHR in a single-day rest/stress 99mTc-sestamibi SPET perfusion protocol and compared these measurements with perfusion defect size (PDS) and angiographic severity of CAD. Severe CAD was defined as >75% left main coronary stenosis and/or >90% proximal left anterior descending artery stenosis and/or >90% proximal stenosis in the left circumflex and right coronary arteries. LHR was determined from a stress anterior planar image recorded < or =6 min after exercise. TID ratio was derived from automatically calculated left ventricular rest/stress volumes, and PDS was measured based on semi-automated computer software (CEqual). Diagnostic accuracy and predictive values were compared between 22 patients with severe and 98 patients without severe CAD. LHRs showed a higher sensitivity (73%) for the assessment of severe CAD as compared to PDS and TID ratio (41% and 23% respectively, P<0.01), whereas specificity was highest for TID ratio [95%, P<0.01 when compared to PDS (84%) and LHR (82%)]. It is concluded that increased LHR in 99mTc-sestamibi myocardial perfusion imaging seems to yield good diagnostic accuracy in the detection of patients with severe CAD and may be derived from a single-day rest/stress study.

Coronary Circulation↗
PubMed2000

Closed-loop stimulation using intracardiac impedance as a sensor principle: correlation of right ventricular dP/dtmax and intracardiac impedance during dobutamine stress test.

Changes of the unipolar right ventricular impedance during the cardiac cycle are related to the changing content of blood (low impedance) and tissue (high impedance) around the tip of the pacing electrode. During myocardial contraction, the impedance continuously increases reaching its maximum in late systole. This impedance increase is thought to correlate with right ventricular contractility, and thus, with the inotropic state of the heart. In the new Inos2 DDDR pacemaker, integrated information from the changing ventricular impedance (VIMP) is used for closed-loop regulation of the rate response. The aim of this study was to analyze the effect of increasing dobutamine challenge on RV contractility and the measured impedance signals. In 12 patients (10 men, 68 +/- 12 years) undergoing implantation of an Inos2 DDDR pacemaker (Biotronik), a right ventricular pigtail catheter was inserted for continuous measurements of RV-dP/dtmax and simultaneous VIMP signals during intrinsic and ventricular paced rhythm. Then, a stress test with a stepwise increase of intravenous dobutamine (5-20 micrograms/kg per min) was performed. To assess the relationship between RV contractility and measured sensor signals, normalized values of dP/dtmax and VIMP were compared by linear regression. There was a strong and highly significant correlation between dP/dtmax and VIMP for ventricular paced (r2 = 0.93) and intrinsic rhythm (r2 = 0.92), although the morphologies of the original impedance curves differed quite substantially between paced and intrinsic rhythm in the same patient. Furthermore, VIMP correlated well with sinus rate (r2 = 0.82), although there were at least four patients with documented chronotropic incompetence. We conclude, that for intrinsic and ventricular paced rhythms sensor signals derived from right ventricular unipolar impedance curves closely correlate with dP/dtmax, and thus, with a surrogate of right ventricular contractility during dobutamine stress testing. Our results suggest that "inotropy-sensing" via measurement of intracardiac impedance is highly accurate and seems to be a promising sensor principle for physiological rate adaptation in a closed-loop pacing system.

Aged↗
PubMed1997

Noninvasive stress testing of myocardial ischemia: comparison of GRE-MRI perfusion and wall motion analysis to 99 mTc-MIBI-SPECT, relation to coronary angiography.

In the evaluation of ischemic heart disease only MR imaging seems to have the potential to assess myocardial perfusion, function, and coronary morphology on a single instrument. The aim of this study was to assess the feasibility of a stress test with dipyridamole (0. 56 mg/kg) to analyze myocardial perfusion by Gd first-pass enhancement in ultrafast gradient-recalled-echo MRI (perf-MRI), and wall motion by cine gradient-recalled-echo MRI (Cine-MRI) in one imaging session. Twelve patients underwent complete rest and stress studies; satisfactory MR images were acquired in 10 patients. By 99 mTc-MIBI-SPECT sensitivities to detect ischemic segments were 66.7 % with Perf-MRI, 80.0 % with WM-MRI and 86.7 % for Perf-WM-MRI (Perf-MRI vs Perf-WM-MRI; p = 0.03). Scar was equally detected with a sensitivity of 91.6 % with either MRI technique. Thus, Perf-Cine-MRI provides complementary information for the management of ischemic heart disease and has a higher sensitivity than Perf-MRI alone.

Contrast Media↗