Showing papers by "Heart and Diabetes Center North Rhine-Westphalia published in 2004"

Echo-guided percutaneous septal ablation for symptomatic hypertrophic obstructive cardiomyopathy: 7 years of experience.

Abstract: Aims: To analyze the impact of intra-procedural echocardiographic imaging on the interventional strategy in ethanol-induced septal ablation (PTSMA) for symptomatic hypertrophic obstructive cardiomyopathy (HOCM), based on a single-center experience of 7 years. Methods and results: PTSMA was intended for refractory symptoms in 337 patients (pts.) with HOCM (mean age: 54±15 years), with 312 procedures completed by injection of 2.8±1.2 ml ethanol. In 25 pts. (8%) the intervention was aborted without ethanol injection, mostly because of echocardiographic findings ( n = 18/6%). An echocardiography-driven target vessel change was necessary in 33 pts. (11%). In the 312 pts. who received ethanol, permanent pacing was necessary in 22 cases (7%). In-hospital mortality was 1.3% (4 pts.). After 3 months, mean NYHA functional class was reduced from 2.9±0.5 to 1.5±0.6 ( p <0.0001) along with a gradient reduction from 60±33 to 13±18 mmHg at rest, and from 120±43 to 38±35 mmHg with provocation ( p <0.0001 each). Exercise capacity improved from 94±51 to 115±43 W, peak oxygen consumption from 18±4 to 21±6 ml/kg/min ( p <0.01 each). There was no significant difference regarding residual gradients in pts. with different levels of immediate gradient reduction during probatory balloon occlusion. Conclusions: Catheter-based septal ablation is an effective non-surgical technique for reducing symptoms and outflow gradients in HOCM. Intra-procedural echocardiographic guidance has a cumulative impact on the interventional strategy in about 15–20%, and clearly identifies pts. who should not receive ethanol but undergo a surgical myectomy.

A Method to Remove Artifacts in Attenuation-Corrected Myocardial Perfusion SPECT Introduced by Misalignment Between Emission Scan and CT-Derived Attenuation Maps

Abstract: Nonuniform soft-tissue attenuation affects the diagnostic accuracy of SPECT in myocardial perfusion imaging. The attenuation map required for attenuation correction can be acquired using x-ray tomography (CT). Frequent findings in attenuation-corrected images are defects in the apical and anterior myocardial wall. We assume that these are artifacts produced by misalignment of SPECT images and the attenuation map. Methods: One hundred forty patients underwent myocardial perfusion imaging with 99mTc-methoxyisobutylisonitrile. Twenty-seven of 140 showed pronounced defects in the apical or anterior wall only after CT-based attenuation correction. SPECT and corresponding CT slices were examined for misalignment in the ventrodorsal direction (y-direction) visually and by threshold-based delineation of the body surface. Mismatched studies were realigned and image reconstruction and analysis were redone. The effect of the correction was assessed visually and by semiquantitative analysis based on a 20-segment model using 4D-MSPECT. Results: In 15 of 27 patients, the improved coregistration led to smaller and less-pronounced defects in the regions mentioned. In 6 of 27 patients, former defects were judged as normal. No improvement was seen in only 4 patients. In these 4 subjects, the mismatch in the y-direction was

Scintigraphy for Risk Stratification of Iodine-Induced Thyrotoxicosis in Patients Receiving Contrast Agent for Coronary Angiography: A Prospective Study of Patients with Low Thyrotropin

Abstract: The risk of iodine-induced thyrotoxicosis in euthyroid patients receiving iodine-containing contrast agents is known to be low, but data on this risk in patients with latent hyperthyroidism are scarce. We investigated the role of thyroid scintigraphy using Tc-99m preceding the application of iodine-containing contrast material to estimate the risk of iodine-induced thyrotoxicosis in patients with low levels of TSH. In a prospective study on 91 patients, thyroid scintigraphy was performed before coronary angiography (CA). In patients with technetium thyroid uptake (TCTU) less than 1%, CA was done without prophylactic drugs (n = 56). Patients with TCTU greater than 1% were treated either with 900 mg of perchlorate or, depending on the autonomous volume, combined with 20 to 60 mg thiamazole. In the 56 patients with TCTU less than 1%, no case of iodine-induced hyperthyroidism occurred within 4 wk after CA. In the patients who received prophylactic drugs, two cases of mild thyrotoxicosis were observed. Our data suggest that in patients with low levels of TSH, the risk of hyperthyroidism after application of iodine-containing contrast media is negligible if TCTU is less than 1%. In these patients, CA can be performed without administration of prophylactic drugs.

Home monitoring of patients after prosthetic valve surgery -- experimental background and first clinical attempts.

Abstract: Purpose The purpose of this study was to investigate whether: 1. sound phenomena may be used to detect prosthetic valve dysfunction; 2. clinical and experimental data permit conclusions about alterations in the functional state of mechanical valves; 3. patients can record and pass on signals via Internet. Methods 1. We implanted bi-leaflet valves in pigs. By gradually influencing the motion of the tilting discs prosthetic dysfunction could be generated. 2. Thrombosis and lysis of bi-leaflet valves was studied in sheep. This process was documented using echocardiography and acoustically by the Fast Fourier Transformation. 3. Thirty devices were set up and handed out to patients following mechanical valve replacement. All patients regularly sent data to the hospital via Internet, regardless of their location at the time. The data were evaluated by comparing them with the reference file. Results Animal experiments proved that changes in prosthetic function led to a significant change in sound phenomena. In contrast to echocardiography alterations at an early stage (onset of thrombosis) could be reliably verified. The sensitivity was greater than in echo-control analysis. All patients regularly recorded and passed on their signals. Surveys revealed high acceptance and easy handling of the devices. Conclusions Online registration of sound phenomena seems to be suitable for the detection of changes in prosthetic function. This led to the development of the first hand-held device for home monitoring of valve function. Registration of flow, frequency spectrum, and ECG envisaged at the next level opens up potential applications for Internet-based, remote monitoring of cardiac patients.

A sensitive noninvasive method for monitoring successful liver-directed gene transfer of the low-density lipoprotein receptor in Watanabe hyperlipidemic rabbits in vivo

Abstract: Noninvasive tools to quantitate transgene expression directly are a prerequisite for clinical gene therapy. We established a method to determine location, magnitude, and duration of low-density lipoprotein (LDL) receptor (LDLR) transgene expression after adenoviral gene transfer into LDLR-deficient Watanabe hypercholesterolemic rabbits by following tissue uptake of intravenously injected (111)In-labeled LDL using a scintillation camera. Liver-specific tracer uptake was calculated by normalizing the counts measured over the liver to counts measured over the heart that represent the circulating blood pool of the tracer (liver/heart (L/H) ratio). Our results indicate that the optimal time point for transgene imaging is 4 h after the tracer injection. Compared with control virus-injected rabbits, animals treated with the LDLR-expressing adenovirus showed seven-fold higher L/H ratios on day 6 after gene transfer, and had still 4.5-fold higher L/H ratios on day 30. This imaging method might be a useful strategy to obtain reliable data on functional transgene expression in clinical gene therapy trials of familial hypercholesterolemia.

Misalignment between emission scan and X-ray CT derived attenuation maps causes artificial defects in attenuation corrected myocardial perfusion SPECT

Abstract: Attenuation correction increases the specificity of myocardial perfusion SPECT However, we noticed an unusually high number of scans with defects only visible in the attenuation-corrected images We suspected these to be false positive readings Visual inspection using the supplied software suggested mismatch in the ventrodorsal (Y-) direction between SPECT images and transmission maps as an explanation As the fusion tool only allows for a coarse grading, we wrote software to quantify the mismatch A phantom study was done to verify that the observed mismatch can cause the defect patterns visible in the attenuation-corrected images 25 patients who showed the most pronounced artifact were chosen for re-alignment and re-evaluation Overall, the defects in the attenuation-corrected images got less intense (15/25) or even vanished (6/25) after re-aligning emissions images and transmission maps In response to our complaints, the vendor replaced the support rollers which should prevent the bed from deflecting with a re-engineered, more robust version No more clinically relevant artefacts were observed after this modification Evaluation of another 28 probably-normal patients showed the mean mismatch between emission and transmission scan to be significantly reduced We conclude that great care has to be taken to ensure correct alignment of the scans even in a dual-modality imaging device Bed deflection can be a major source for misalignment and artifacts