Biomedical subjects

G Goerge

Publications and source records attributed to G Goerge.

5 recordsLinked to original sources

PubMed1998

Improved assessment of coronary stenosis severity using the relative flow velocity reserve.

BACKGROUND: Myocardial fractional flow reserve (FFR) is based on pressure measurements. We have now sought to establish a Doppler-based concept of relative flow velocity reserve (RFVR) for the functional assessment of stenosis severity in epicardial coronary arteries. A clear threshold value to discriminate the functional severity of a coronary stenosis does not exist for coronary flow velocity reserve (CVR) based on intracoronary Doppler measurements. In contrast, the concept of FFR, which is based on intracoronary pressure measurements, has been extensively validated. An FFR value below 0.75 reliably indicates a significant stenosis. METHODS AND RESULTS: RFVR is calculated as the ratio between distal CVR in the stenosed target vessel and distal CVR in a nonstenotic reference vessel. In 21 patients, RFVR was determined in 24 target vessels by use of intracoronary adenosine and correlated to the FFR, determined as the ratio of mean poststenotic to aortic pressures, in the target vessel. Stenosis severity was classified according to quantitative coronary angiography analysis. Reference diameter was 3.0+/-0.4 mm (mean+/-SD), and area stenosis was 74+/-15% (range, 40% to 95%). CVRs in the target and reference vessels were 2.1+/-0.5 and 2.6+/-0.7, respectively. FFR ranged from 0.49 to 0.99 (mean, 0.81+/-0.15) and RFVR from 0.53 to 1.0 (mean, 0.82+/-0.13). Poststenotic CVR did not correlate with either percent area stenosis (r=0.27, P=NS) or FFR (r=0.33, P=NS). In contrast, FFR as well as RFVR showed a curvilinear relation to percent area stenosis (r=0.89, P<0.0001 and r=0.79, P<0.0001, respectively). There was a close linear correlation between FFR and RFVR (r=0.91, P<0.0001). CONCLUSIONS: RFVR correlates closely to FFR and to percent area stenosis, whereas the correlation of CVR with FFR and percent area stenosis is rather poor. RFVR is a promising new concept for assessment of coronary stenosis severity and clinical decision making based on Doppler measurements.

Aged↗

PubMed1998

Current concepts of coronary flow reserve for clinical decision making during cardiac catheterization.

Measurements of coronary flow reserve, once used only for research, have gained wide acceptance as an additional diagnostic approach in the decision-making process of diagnostic cardiac catheterization and coronary interventions. Apart from the noninvasive determination of coronary flow reserve, intracoronary Doppler flow wires have facilitated decision making in the catheterization laboratory. Different techniques, unstandardized procedures, and data from uncomparable patient populations have remained a confounding factor. This review examines current concepts of coronary flow reserve as well as methodologic considerations and pitfalls. Applications of coronary flow reserve for periinterventional assessment are evaluated on the background of practical guidance. According to a detailed examination of arterial structure and function, a normal coronary flow reserve exceeds a value of 3.0. Values below 3.0 suggest involvement of microvascular disease caused by functional or structural alterations. The influences of various factors such as age, hemodynamics, hypercholesterolemia, hypertrophy, hypertension, syndrome X, and coronary artery disease are discussed in relation to the effect on coronary flow reserve. From available information, measurements of coronary flow reserve are an adjunct to current interventional technology to optimize individual patient care. Further efforts should be undertaken to incorporate these new methods into our routine clinical decision making.

Blood Flow Velocity↗

PubMed1997

Comparison of electron beam computed tomography with intracoronary ultrasound and coronary angiography for detection of coronary atherosclerosis.

OBJECTIVES: This analysis compared the results of electron beam computed tomography (EBCT) with those of coronary angiography and intracoronary ultrasound (ICUS) for the in vivo detection of coronary atherosclerotic plaques. BACKGROUND: EBCT is a new imaging modality for identification of coronary calcifications. Coronary angiography depicts advanced changes in coronary morphology, whereas ICUS is an established diagnostic tool that detects the early stages of coronary artery disease. METHODS: In 57 patients (54 +/- 9 years old), 267 coronary segments were analyzed with EBCT (3-mm slices, acquisition time 100 ms, threshold definition of coronary calcification at 130 Hounsfield units in an area > or = 1 mm2, Agatston calcium score), coronary angiography and ICUS. The analysis was based on the number and extent of coronary calcifications on EBCT, coronary lumen reduction on coronary angiography and plaque formation with and without ultrasound signs of calcifications on ICUS. RESULTS: Compared with coronary angiography, EBCT yielded a sensitivity of 66%, a specificity of 78%, a positive predictive value of 39% and a negative predictive value of 91%. Compared with ICUS, EBCT yielded an overall sensitivity of 66%, a specificity of 88% and an overall accuracy of 81%. For plaques with and without ultrasound signs of calcifications, the sensitivity of EBCT was 97% and 47%, specificity 80% and 75% and overall accuracy 82% and 69%, respectively. CONCLUSIONS: This in vivo correlation between ICUS and EBCT demonstrates that EBCT is a noninvasive method that helps to visualize the atherosclerotic process by localization and quantification of coronary artery calcifications. EBCT detects calcified plaques with high accuracy. Plaques without ultrasound signs of calcifications can be detected by EBCT but with lower sensitivity but equivalent specificity.

Adult↗

PubMed1996

Equipment configuration and procedures: preferences for interventional microtherapy.

Magnetic resonance imaging (MRI), computed tomography, and electron beam tomography scanners are built for radiologic diagnosis. With increasing frequency they are being used in the field of interventional Microtherapy to permit transparent visualization of the therapeutic field. Each of these scanners can be combined with endoscopy, fluoroscopy/digital subtraction angiography, and ultrasound units for hybrid imaging techniques as well as with therapeutic systems like lasers or radiofrequency. MRI affords 3D localization without x-ray exposure. Open access and keyhole imaging allow nearly real time guidance of instruments. Minimally invasive techniques using endoscopes and hybrid tomographic guidance result in improved tip tracking of microinstruments and reduced complications. This safer access into the body will lead to interdisciplinary cooperation with the potential for large cost reductions. This report summarizes our experience regarding which of the hybrid imaging suites is best suited for procedures including among others drug instillations, prosthesis (stent) implantation, or microoperations (endoscopic diskectomy/sequestrectomy), and physiological measurements simultaneously.

Diagnostic Imaging↗

PubMed1989

[Possibilities and limits of 2-dimensional echocardiography in quantitative image analysis].

By two-dimensional echocardiography left ventricular volumes can be measured and ejection fraction can be calculated. But volume and ejection fraction determination are combined with a systematic underestimation despite high correlation in comparison to "true volume", whereas cineventriculography systematically overestimates true volume. This echocardiographic methodological problem is related not only to tangential scanning but also to low lateral resolution yielding a reduced endocardial border delineation. Meanwhile, advanced transducer technology and digital imaging techniques with zoom and cineloop possibilities have improved endocardial border detection. In comparison to cineventriculography, volume determination by two-dimensional echocardiography has improved significantly in comparison to results in 1983; this improvement was mainly due to a better determination of endsystolic volume. Similarly, left ventricular contrast echocardiography using color coding with statistical analysis of digitized images enhanced the accuracy of analysis of global and regional left ventricular function. Transesophageal echocardiography will be used when there is reduced image quality of transthoracic echocardiography, for example, in obese patients or those with pulmonary emphysema or mechanical ventilation. Transthoracic echocardiography has become a routine method for assessing global and regional left ventricular function. Echoventriculography can be used in patients with renal insufficiency, anaphylactic reaction to contrast medium, and poor left ventricular function.

Algorithms↗