Stress Echocardiography

Stress echocardiography, both pharmacologic and physiological, is an established noninvasive diagnostic method of detecting coronary artery disease. It also has a role in the assessment of patients with chest pain, the assessment of cardiovascular risk before noncardiac surgery, the assessment of patients after a myocardial infarction, the detection of viability in dysfunctional myocardium, and the prediction of functional recovery. The prognostic value of stress echocardiography is emerging. In this article, we discuss the methodology, diagnostic accuracy, and various clinical applications of stress echocardiography. We also review its limitations and compared it with other noninvasive methods of assessing patients with coronary artery disease.     

Studies on the Inhibitory Effects of Analogues of Dapsone on Neutrophil Function In-vitro*

We have compared twelve sulphone analogues of dapsone in terms of inhibition both of zymosan-mediated human neutrophil respiratory burst and inhibition of interleukin-1-stimulated neutrophil adhesion to transformed human umbilical vein endothelial cells. Overall, there was a good correlation between the respective rank orders of compound potency in the two test systems. The most effective compounds in terms of respiratory burst and adherence inhibition were the 2-nitro-4-amino-, 2-hydroxy-4-aminopropyl-, and 2-methoxy-4-aminoethyl- derivatives. In general, potency was inversely associated with lipophilicity; compounds with bulky side-chains, e.g. the 2-methyl-4-aminopentyl, 2-methyl-4-aminohexyl and the 2-hydroxymethyl-4-aminoethyl derivatives, were less potent. A 2-hydroxy-4-amino- derivative was the exception, however, with low lipophilicity and relatively low potency. All of the compounds tested showed comparable or greater inhibition in both the neutrophil-mediated assays compared with dapsone. Some of the compounds might, because of their good tissue penetration and lower toxicity than dapsone, have the potential to undergo further development.     

The Effects of Extracorporeal Shock Wave Lithotripsy on Pacemaker Function

Twenty-two pacemaker pulse generators were exposed to shock waves of an extracorporeal shock wave lithotripter to assess the effects of the extremely high pressure transients on pacemaker function. The pulse generator and distal aspect of the lead were positioned 5 cm from the focal point of the lithotripter and 10 cm from each other. Pulse generator function was analyzed during shock wave delivery synchronized with pulse generator output, during shock waves at a rate faster than the escape rate, and after exposure to lithotripsy. During shock waves delivered synchronously with pulse generator output, only one of 22 pulse generators malfunctioned by intermittently reverting to the magnet rate. When subjected to shock waves at a rate greater than the escape rate, 50% of the pulse generators were inhibited by electromechanical interference from the lithotripter. Both bipolar and unipolar devices were affected. However, analysis after exposure to shock waves showed that none of the pacemakers was damaged or spuriously reprogrammed. In conclusion, cardiac pacemakers do not appear to be damaged or reprogrammed by exposure to extracorporeal shock wave lithotripsy. The likelihood of false inhibition appears to be very low if shock waves are delivered synchronously with the QRS.     

Relationship between myocardial norepinephrine content and left ventricular function -- an endomyocardial biopsy study

To analyze the relationships between left ventricular function,catecholamine concentrations in plasma and myocardium, and morphologicalalterations. 20 patients were studied. Fifteen patients hadidiopathic dilated cardiomyopathy, and 5 had normal left ventricularfunction All Patients underwent right ventricular endomyocardialbiopsy to determine muscle fibre thickness. percent volume fractionof interstitium, and myocardial catecholamine content. Bloodwas sampled to measure plasma catecholamine concentrations,and left ventricular cineangiography was performed to determineglobal ejection fraction. In a simple correlation analysis asignificant correlation was found between left ventricular ejectionfraction and myocardial norepinephrine content (r=0.80, P<0.0001).Left ventricular ejection fraction was negatively correlatedwith plasma epinephrine concentration (r–=0.53. P<0.02),and with muscle fibre thickness (r= –0.50. P< 0.03).Myocardial norepinephrine concentration was negatively correlatedwith plasma epinephrine (r = –0.62, P<0.01). Multiplelinear regression analysis revealed a strong correlation betweenmyocardial norepinephrine depletion and left ventricular dysfunction,which was independent of all other variables. These data suggestthat myocardial norepinephrine depletion determined from rightventricular endomyocardial biopsies strongly correlates withleft ventricular dysfunction in idiopathic dilated cardiomyopathy,and seems to be independent of the degree of muscle fibre hypertrophy,volume fraction of interstitium, and of the increased sympathetictone.     

Studies of the Tissue Reaction Induced by Transvenous Pacemaker Electrodes. I. Microscopic Examination of the Extent of Connective Tissue Around the Electrode Tip in the Human Right Ventricle

The purpose of this study was to investigate the extent of connective tissue of the human right ventricle induced by cardiac pacing electrodes. Between January 1984 and July 1987, 34 consecutive patients with VVI-pacing systems were autopsied in the Department of Pathology at the University of Frankfurt/M. The surrounding tissue of these 34 electrodes (17 Siemens Elema 412 S, five Medtronic 6957, one Medtronic 6959, one Medtronic 4011, three Biotronik D2K, three Biotronik K10, two Osypka FY 62, one Biotronik N, and one Siemens Elema 588) in the right ventricle were investigated histologically. The tissue was stained with Giemsa and the thickness of the connective tissue layer was measured. Stimulation threshold data at various times were known in four of eight screw-in electrodes, in seven of 17 vitreous carbon electrodes and in two of seven smooth surface electrodes. Electrode surface area, implantation time, age of the patient and cause of death were comparable for all three electrode groups. However, a significant difference was found in the extent of connective tissue between the porous surface and screw-in electrodes (128 ± 55 VS 397 ± 269 μm, P 0.01) and porous surface and smooth surface electrodes (128 ± 55 vs 307 ± 117 μm, P 0.01). No relation (r = 0.106) was found between the duration of implantation and the extent of connective tissue for the vitreous carbon electrodes (Siemens Elema 412 S). The lowest chronic stimulation thresholds were measured in the latter type of electrodes (0.5 ± 0.3 V) as compared to the screw-in (0.75 ± 0.30 V) and smooth surface electrodes. We conclude from this study, that vitreous carbon electrodes induce only a small amount of connective tissue around the insertion site in the human right ventricle, as compared to other smooth surface or screw-in electrodes. Chronic stimulation threshold data parallel those morphological results.     

Scintigraphic evidence that the right ventricular myocardium tolerates ischaemia better than the left ventricular myocardium

To study the incidence of right ventricular infarction and theeffect of intracoronary thrombolysis on the ischaemic rightventricular myocardium, we performed intracoronary myocardialthallium scintigraphy in 18 patients with complete occlusionof the right coronary artery who underwent intracoronary thrombolysis.In 15 of these patients, intracoronary thallium-201 and technetium-99m pyrophosphate scintigrams were performed simultaneously. All18 patients had a right ventricular thallium defect before thrombolysis,and all had new thallium uptake after thrombolysis. 17 out of18 patients had a left ventricular thallium defect before thrombolysis,but only 10 of them showed new thallium uptake after thrombolysis.14 out of 15 patients had a left ventricular technetium-99 mpyrophosphate spot after thrombolysis and some diffuse pyrophosphateaccumulation in the area of the right ventricle. In one patientpyrophosphate accumulation was found only in the area of theright ventricle. Thus, right ventricular thallium defects weredetected by intracoronary thallium scintigraphy in the majorityof patients with inferior acute myocardial infarction due toright coronary artery occlusion. Right ventricular thalliumdefects were always reversible in contrast to left ventricularthallium defects in the same patients, suggesting that rightventricular myocardium tolerates ischaemia better than leftventricular myocardium.     

Advances in three-dimensional diagnostic radiology

The maturity of current 3D rendering software in combination with recent developments in computer vision techniques enable an exciting range of applications for the visualisation, measurement and interactive manipulation of volumetric data, relevant both for diagnostic imaging and for anatomy. This paper reviews recent work in this area from the Image Sciences Institute at Utrecht University. The processes that yield a useful visual presentation are sequential. After acquisition and before any visualisation, an essential step is to prepare the data properly: this field is known as ‘image processing’ or ‘computer vision’ in analogy with the processing in human vision. Examples will be discussed of modern image enhancement and denoising techniques, and the complex process of automatically finding the objects or regions of interest, i.e. segmentation. One of the newer and promising methodologies for image analysis is based on a mathematical analysis of the human (cortical) visual processing: multiscale image analysis. After preprocessing the 3D rendering can be acquired by simulating the ‘ray casting’ in the computer. New possibilities are presented, such as the integrated visualisation in one image of (accurately registered) datasets of the same patient acquired in different modality scanners. Other examples include colour coding of functional data such as SPECT brain perfusion or functional magnetic resonance (MR) data and even metric data such as skull thickness on the rendered 3D anatomy from MR or computed tomography (CT). Optimal use and perception of 3D visualisation in radiology requires fast display and truly interactive manipulation facilities. Modern and increasingly cheaper workstations (<$10000) allow this to be a reality. It is now possible to manipulate 3D images of 256³ at 15 frames per second interactively, placing virtual reality within reach. The possibilities of modern workstations become increasingly more sophisticated and versatile. Examples presented include the automatic detection of the optimal viewing angle of the neck of aneurysms and the simulation of the design and placement procedure of intra-abdominal aortic stents. Such developments, together with the availability of high-resolution datasets of modern scanners and data such as from the NIH Visible Human project, have a dramatic impact on interactive 3D anatomical atlases.     

LAPAROSCOPIC RADICAL PROSTATECTOMY WITH THE HEILBRONN TECHNIQUE: AN ANALYSIS OF THE FIRST 180 CASES

PURPOSE: In 1998 Guillonneau and Vallancien introduced laparoscopic radical prostatectomy with primary access to the seminal vesicle. In 1999 we developed a different laparoscopic technique similar to the classic retropubic radical prostatectomy. We focus on early results and the learning curve of the procedure in the first 180 patients. MATERIALS AND METHODS: A transperitoneal approach is used with immediate access to Retzius' space. After the dorsal vein complex is endoscopically sutured, the urethra is incised and distal pedicles of the prostate with or without the neurovascular bundle transected. The apex is then pulled ventrally followed with incision at the bladder neck, and transvesical access to vas deferens and seminal vesicle. After completing the posterior wall of the urethrovesical anastomosis with 5 interrupted endoscopic sutures, the Foley catheter is placed, bladder neck closed and specimen extracted via the umbilical incision. From March 1999 to December 2000 we have performed 180 procedures, including 3 for stage pT1 tumor, 88 pT2, 82 pT3 and 7 pT4. Mean preoperative PSA was 13.3 ng./ml. (range 1.4 to 148), mean specimen weight 37.4 gm. (10 to 125) and median Gleason score 6 (3 to 9). For evaluation of the learning curve a separate analysis of 3 groups with 60 patients in each was done. Differences between groups 1 (first 60 patients) and 3 (last 60) were analyzed for statistically significant differences. RESULTS: Mean operating time was 271 minutes (range 150 to 500) and transfusion rate 31%. The reintervention rate was 4.4% and complication rate 18.8%. Of the patients 92% did not require any analgesia on postoperative day 2. Positive margins were found in 16% of the patients. The rate of positive margins in pT2 tumors was 2.3%, pT3a 15% and pT3b 34%. After a median followup of 12 months (range 3 to 23) in 9 (5%) patients a prostate specific antigen relapse was observed. The anastomosis was tight after removal of the catheter in 83% of patients, with a median time of 7 days (range 5 to 30). An anastomotic stricture had to be treated with laser incision in 3.3% of patients. On discharge from the hospital 33% of patients were continent, after 6 months 74% and after 12 months 97%. Analysis of the learning curve revealed significant differences in operating time (324 versus 265 minutes), conversion rate to open surgery (8.1% versus 1.7%), complication rate (23.3% versus 11.7%) and rate of prolonged catheterization (31.6% versus 10%, respectively), whereas the percentage of positive margins and continence rates showed no influence. CONCLUSIONS: Laparoscopic radical prostatectomy requires significant laparoscopic expertise with an ongoing learning curve. Morbidity is low, oncological control similar to results of open surgery and functional results are promising. The procedure should be performed only at dedicated centers with adequate training and expertise.