Contribution of CT to treatment planning in patients with GIST.

PURPOSE: The aim of this study was to illustrate the morphological and structural computed tomography (CT) patterns of gastrointestinal stromal tumours (GIST) and to discuss the technique's role in identifying lesions at a higher risk for malignant potential, in treatment planning and in the follow-up of patients with GIST. MATERIALS AND METHODS: We retrospectively reviewed the CT scans of 26 patients who underwent surgery for histologically confirmed GIST of the stomach (20 cases), the duodenum (1), the caecum (1), the small bowel (2), the descending colon (1) and the rectum (1). CT exams were performed with a single-slice scanner and a 5-mm collimation before and after the intravenous administration of contrast material. RESULTS: CT allowed us to correctly define the site, size and structure of lesions in all cases and to identify signs of invasion of neighbouring structures in some cases. The lesions exhibited solid density on the unenhanced scan and poor enhancement after contrast-medium administration; lesion structure was homogeneous in ten cases and inhomogeneous in 16; in one case, histology revealed microcalcification that had not been detected by CT. CONCLUSIONS: CT, with its panoramic capabilities and high contrast resolution, provides essential information for treatment planning and for the follow-up of GIST patients treated with surgery or chemotherapy.

Radiologic evaluation in planning surgery of renal tumors.

The evolution in diagnostic imaging modalities, mainly in computed tomography (CT) and magnetic resonance imaging (MRI), have made it possible to extend the applications of these techniques from diagnosis to staging and surgical planning. Nowadays, the possibility to present images on different planes with an intrinsic resolution close to that of the original axial sections allows presentation of the kidney on sagittal, coronal, and oblique planes. Three-dimensional reconstructions can be obtained with different methods and have attained excellent image quality. Multidetector spiral CT presently is the best technique for planning surgery, but MRI also enables high-quality images to be obtained if state-of-the-art equipment is available. This update reviews the current status and possibilities of diagnostic imaging modalities in planning surgery of renal tumors.

New automatic software for virtual colonoscopy: technical aspects.

PURPOSE: To evaluate a new virtual endoscopy software package capable of automatically plotting the path along which to perform endoscopic exploration. MATERIALS AND METHODS: We reviewed the examinations of 50 patients with colonic neoplasms studied by CT colonoscopy by using a single-detector CT scanner (Philips Tomoscan AVE1). The technical parameters used were: slice thickness 3 mm, pitch 1.4, reconstruction interval 2-2.5, 120 kV, 150-200 mA. The images were processed on a separate workstation (Philips Easy Vision 5.1) running an experimental virtual endoscopy software package capable of automatically drawing a line along which to move the virtual endoscope to explore the colon. Reconstruction of the endoscopic images along the path obtained was set at an interval of 15-20 mm between one endoscopic view and the next, to a total of 70 to 120 images. The endoscopic animated image sequence was then saved and evaluated by comparing the starting axial images and the three-dimensional images obtained. RESULTS: The programme plotted the endoscopic path correctly in a single pass in 40 of the 50 cases studied. The overall time spent by the radiologist on image-processing did not exceed 5 minutes. DISCUSSION: The need to reduce the time spent by audiologists on post-processing has led to a gradual improvement in image-processing hardware and software. In the context of virtual endoscopy, one of the main goals is to obtain the path for endoscopic exploration in as short a time as possible. The programme we evaluated successfully fulfils this requirement as, once the image-processing technical parameters have been defined, it plots a path along the entire colon and performs the reconstruction procedures automatically. The time spent by the operator on post-processing does not exceed 5 minutes. CONCLUSIONS: The new programme evaluated in this study facilitates the processing of endoscopic images, reduces radiologist time and may contribute to the widespread use of virtual colonoscopy.

Usefulness of virtual endoscopic three-dimensional reconstructions of the middle ear.

This work uses a new programme for producing 3D radiological images acquired by means of CT which enables the internal surfaces of the examined structures to be visualized. This new method, which is able to navigate inside organs in a similar way to fibreoptic endoscopy, is known as virtual endoscopy. CT examinations of the temporal bone were carried out using spiral equipment and endoscopic 3D processing was carried out on a separate workstation equipped with a volume-rendering programme. Once the technical parameters necessary for obtaining a representation of the internal surfaces had been defined, a simulation of a virtual otoscopy was conducted by moving the virtual endoscope from the external auditory canal through the annulus to the tympanic cavity. The simulation can be obtained either by moving the endoscope by hand, using the mouse, or by defining a path along which the software automatically creates an endoscopic 3D reconstruction. The images thus obtained are projected sequentially to give a "movie" effect, i.e. a continuous progression of the endoscope. The average time required to conduct the procedure ranges from 20 to 30 min. A virtual endoscopic visualization of the middle ear was obtained which, in particular, generated images of the tympanic cavity with the ossicular chain. In our experience, virtual otoscopy shows the anatomy of the structures of the tympanic cavity in excellent detail and may be considered complementary to CT, providing useful images enabling better visual representation and understanding of this complex structure. Although clinical applications of the technique remain to be defined it may have a role to play in presurgical diagnostic evaluation of the ossicular chain, epitympanum and retrotympanum.

[Effective dose in X-ray examinations: comparison between spiral CT and urography in the study of renal colic]. / Dose efficace in indagini radiologiche: confronto tra TC spirale ed urografia nello studio della colica renale.

AIM: The aim of this study was to calculate the effective dose in patients with renal colic undergoing spiral CT examination and IVU examination, and to verify the ability of the systems to measure the effective dose. MATERIAL AND METHODS: Dose measurements were carried out for both diagnostic techniques by employing an anthropomorphic phantom with thermoluminescence detectors (TLDs) fitted inside the phantom. The data so obtained were compared with dose estimations based on published tables, which allow to obtain the effective dose on the basis of the experimental value of common dose indicators, the performance of the equipment and the setting of the acquisition parameters for such examinations. RESULTS: The absorbed dose inside the phantom had an homogeneous distribution during the spiral CT examination, while during the IVU there were significant differences in the absorbed dose between different zones of the body, due to the geometry of the x-ray beam. The mean effective dose, which corresponds to the average of values absorbed by males and females, measured by TLD dosimeters for spiral CT examination was 3.3 time that for IVU. For both spiral CT and IVU the dose to the male was significantly lower than that to the female, owing to the anatomic position of female gonads that are completely exposed to the x-ray radiations during the study, while male gonads lie outside of the exposed area. Both methods for estimating the effective dose in spiral CT, based on CTDI value, significantly underestimated the value derived from experimental TLDs measurement. The evaluation of effective dose in IVU, based on the measurement of the skin dose in air, overestimated the measurement performed by TLDs. DISCUSSION AND CONCLUSIONS: Dose measurement performed by TLD dosimeters fitted inside an anthropomorphic phantom has the advantage of calculating experimentally the absorbed dose in different anatomic districts. However, the method is quite difficult, and introduces some imprecisions due to the simplified morphology of the phantom and the measuring system of TLDs (+/- 10%). Another possibility is to make theoretical estimations on the basis of simple dose measurements. Also these methods are affected by many factors that may introduce imprecisions, such as the patient geometry which has a considerable effect on the dose distribution inside the body. Therefore the methods of measurement based on CTDI value can provide only rough estimations of effective dose. The same considerations can be applied to IVU; in this case the theoretical estimations are based on skin dose measurements, which are very accurate but cannot foresee the behaviour of x-rays inside the patient. As regards the diagnostic procedures evaluated, the gonadic absorbed dose has a greater effect on the effective dose value as a consequence of the weight tissue ratio Wt. In this respect we should underline that, while female gonads are completely irradiated during spiral CT and IVU examinations, the male gonads are exposed only to diffuse radiation; this entails a great difference between the effective dose to the male and that to the female. For this reason the effective dose should be expressed not only for the average man (that is the mean value between males and females), but also distinguishing by patient sex. Although the comparison of different evaluating methods confirmed the difficulties in obtaining the exact effective dose, all the measurements performed with IVU and spiral CT showed that the effective dose for CT is 3.3 times that for IVU. However, the excellent image quality obtained by spiral CT and the high intrinsic contrast of stones probably makes it possible to reduce the dose with this technique, preserving an acceptable quality of the diagnostic images.

[Spiral-CT with multiplanar reconstructions (MPRS) in the evaluation of ureteral neoplasms: preliminary results]. / TC spirale e ricostruzioni multiplanari (MPR) nella valutazione dei tumori dell'uretere: risultati preliminari.

PURPOSE: Urothelial tumors of the upper urinary tract (renal pelvis and ureters) are rare: the most common of these are Transitional Cell Carcinomas (TCC), usually localized in the bladder (75% of cases), whereas only 7-10% arise in the renal pelvis and 2,5-5% in the ureter. Multicentricity is not infrequent and synchronous or metachronous tumors have been reported to develop in 11-13% of patients with upper urinary tract cancer and 2-4% of those with bladder cancer. The presence of additional lesions can change patient management. Clinically these tumors may present with hematuria or flank pain, but sometimes there are no specific clinical findings. Radiological studies play an important role in tumor detection and staging and in follow up. The diagnosis is usually performed by IVU and US, while CT is generally employed in the staging. Our purpose was to verify the role of Spiral CT with Multiplanar Reconstructions (MPRs) in the evaluation of ureteral tumors. MATERIAL AND METHODS: Nine patients with ureteral neoplasms were examined with a single detector spiral-CT, using the following parameters: 120 kV, 200 mA; 5 mm collimation, pitch 1.4, slice reconstruction every 5 mm; image acquisition 2-5 minutes after injection of 120 cc of contrast medium (300 mgI/ml). All the exams were transferred to a separate workstation to obtain curvilinear MPRs. RESULTS: Spiral CT on the axial plane visualized 4 urothelial tumors as concentric ureteral wall thickening; 3 as intraluminal soft tissue masses, with involvement of almost the entire urinary tract, as far as the bladder in 1 case. In other 2 patients there were synchronous lesions which presented both patterns (wall thickening and intraluminal mass). In all cases the lesions exhibited moderate enhancement after c.m. injection. Medium- to high-grade hydronephrosis above the tumors was always present. On MPRs both ureteral involvement and dilated, urine-filled upper urinary tract were clearly represented on coronal and sagittal oblique planes; these images allowed to visualize the craniocaudal extension of short or long lesions, and to detect multicentricity. DISCUSSION: The radiological diagnosis of ureteral tumors is usually performed by IVU, US and CT. IVU allows to visualize the tumors as filling defects or irregular narrowing of the ureteral lumen. IVU however is unable to show the real extent of the tumor in obstructive disease or in nonfunctioning kidney. US visualizes the lesion as an echoic mass in the lumen, although it is sometimes difficult to differentiate neoplastic lesions from other filling defects and to visualize the entire ureteral tract. CT is generally employed in the staging of ureteral tumors. CT findings are usually very useful for distinguishing ureteral neoplasms from other filling defects based on their attenuation and enhancement characteristics. Spiral CT with MPRs allows to obtain panoramic views of the urinary tract; these images are more effective than those of IVU, because of their capability to show the longitudinal extension of the lesion and the presence of multicentric tumors. Furthermore with MPRs it is possible to visualize the ureteral tract distal to the lesion, overcoming the limitations of IVU in nonfunctioning kidney or obstructive disease. CONCLUSIONS: Spiral CT with MPRs is useful in the evaluation of ureteral tumors as it is capable of visualizing the whole extension of the lesion and the presence or absence of multicentric lesions, which can change patient management.

Evaluation of image quality and dose in renal colic: comparison of different spiral-CT protocols.

The aim of this study was to test different technical spiral-CT parameters to obtain optimal image quality with reduced X-ray dose. Images were acquired with a spiral-CT system Philips Tomoscan AVE1, using 250 mA, 120 kV, and 1-s rotational time. Three protocols were tested: protocol A with 5-mm thickness, pitch 1.6, slice reconstruction every 2.5 mm; protocol B with 3-mm thickness, pitch 1.6, slice reconstruction every 1.5 mm; and protocol C with 3-mm thickness, pitch 2, slice reconstruction every 1.5 mm. Two phantoms were employed to evaluate the image quality. Axial images were acquired, then sagittal and coronal images were reconstructed. Finally, the absorbed X-ray dose for each protocol was measured. Regarding image quality, 5-mm-thick images (protocol A) showed greater spatial resolution and lower noise compared with 3-mm-thick images (protocols B and C) on the axial plane; 3-mm reconstructed sagittal and coronal images (protocols B and C) showed an improved image quality compared with 5-mm reformatted images (protocol A). Concerning X-ray dose, the mean dose was: protocol A 19.6 +/- 0.8 mGy; protocol B 14.4 +/- 0.6 mGy; protocol C 12.5 +/- 1.0 mGy. Our study supports the use of thin slices (3 mm) combined with pitch of 1.6 or 2 in renal colic for X-ray dose reduction to the patient and good image quality.

[Current role of color Doppler ultrasound in acute renal failure]. / Stato attuale dell'eco color-Doppler nell-insufficienza renale acuta.

Acute Renal Failure (ARF) is characterized by a rapid decline of the glomerular filtration rate, due to hypotension (prerenal ARF), obstruction of the urinary tract (post-renal ARF) or renal parenchymal disease (renal ARF). The differential diagnosis among different causes of ARF is based on anamnesis, clinical symptoms and laboratory data. Usually ultrasound (US) is the only imaging examination performed in these patients, because it is safe and readily available. In patients with ARF gray scale US is usually performed to rule out obstruction since it is highly sensitive to recognize hydronephrosis. Patients with renal ARF have no specific changes in renal morphology. The size of the kidneys is usually normal or increased, with smooth margins. Detection of small kidneys suggests underlying chronic renal pathology and worse prognosis. Echogenicity and parenchymal thickness are usually normal, but in some cases there are hyperechogenic kidneys, increased parenchymal thickness and increased cortico-medullary differentiation. Evaluation of renal vasculature with pulsed Doppler US is useful in the differential diagnosis between prerenal ARF and acute tubular necrosis (ATN), and in the diagnosis of renal obstruction. Latest generation US apparatus allow color Doppler and power Doppler evaluation of renal vasculature up to the interlobular vessels. A significant, but non specific, reduction in renal perfusion is usually appreciable in the patients with ARF. There are renal pathologic conditions presenting with ARF in which color Doppler US provides more specific morphologic and functional information. In particular, color Doppler US often provides direct or indirect signs which can lead to the right diagnosis in old patients with chronic renal insufficiency complicated with ARF, in patients with acute pyelonephritis, hepatic disease, vasculitis, thrombotic microangiopathies, and in patients with acute thrombosis of the renal artery and vein. Contrast enhanced US is another useful diagnostic tool in patients with ARF which has been recently introduced in clinical practice. Microbubble administration may reduce technical failure in the evaluation of the renal artery. Moreover, perfusion defects due to stenosis or thrombosis of the renal segmentary vessels are better recognized. New diagnostic possibilities of enhanced US include evaluation of both cortical and medullar vessels, and functional evaluation of renal perfusion. Measuring the transit time of the microbubbles is useful for the diagnosis of renal artery stenosis and, in transplanted kidneys, for differential diagnosis between ATN and acute rejection.

Cost analysis of different protocols for imaging a patient with acute flank pain.

The aim of this study was to analyse the costs of different diagnostic approaches to patients with acute flank pain. Four different diagnostic approaches were considered: (a) spiral CT without contrast medium (CM); (b) plain film, ultrasonography (US) and intravenous urography (IVU)--the latter procedure is used in our department in cases still unsolved following the former investigations (28% in our experience); (c) plain film, US and spiral CT without CM (as an alternative to IVU in 28% of cases); and (d) IVU. The cost of each procedure in a university hospital was calculated, following analysis of the differential costs of each investigation (equipment, depreciation and maintenance costs, related materials and services, radiologists, radiographers, nurses) and their common costs (auxiliary personnel and indirect internal costs). Finally, we calculated the full cost of each procedure and applied it to the different diagnostic approaches. The full cost of each approach was: (a) spiral CT without CM = 74 Euro; (b) plain film, US and IVU (28%) = 66.89 Euro; (c) plain film, US and spiral CT without CM (28%) = 64.93 Euro; (d) IVU = 80.90 Euro. Intravenous urography alone or in unsolved cases is not to be considered because it provides higher costs and worse diagnostic results, whereas X-ray dose to patient is almost equal between IVU and spiral CT. Spiral CT integrated to plain film and US in unsolved cases could be preferred because of lower cost and dose to patient, though reaching a diagnostic conclusion may take longer than an immediate spiral CT.

New onset atrial flutter termination by overdrive transoesophageal pacing: effects of different protocols of stimulation.

AIM: We evaluated the effect of different stimulation protocols on atrial flutter interruption by transoesophageal pacing. METHODS AND RESULTS: Eighty patients with new onset atrial flutter were randomized into four groups. Pacing was attempted under the following conditions: with short bursts (5 s), without treatment (group A) and after oral administration of propafenone 600 mg (group B); with prolonged bursts (30 s), without treatment (group C) and after oral administration of propafenone 600 mg (group D). Pacing interrupted atrial flutter in 20% of patients in A, 55% in B, 50% in C and 85% in D. The use of longer bursts gave better results both in patients without treatment (P < 0.05: C vs A) and in patients with propafenone (P < 0.05: D vs B). Comparing groups with the same stimulation protocol, we observed a better response in patients treated with propafenone (P < 0.05: B vs A and D vs C). In the groups without treatment the use of shorter bursts was associated with a lower induction of stable atrial fibrillation (three vs nine episodes), in the groups on propafenone no differences were observed (one vs one episode). CONCLUSIONS: We conclude that the association of propafenone with long bursts gives the best result for interruption of new onset atrial flutter by transoesophageal pacing.

[Kidney obstruction: potential use of ultrasonography and Doppler color ultrasonography]. / Il rene ostruito: le possibilità dell'ecografia e dell'eco-color Doppler.

Ultrasonography is the first imaging approach in evaluation of patients with urinary obstruction. Presence of hydronephrosis, urinomas and inflammatory complications can be assessed. Moreover, the level and the cause of obstruction are often identified. The major limits of ultrasonography are poor visibility of the lumbar portion of the urinary tract and lack of specificity in detection of pyelocaliectasis. These limits are partially overcome with Doppler studies. Several factors can bias diagnostic accuracy of colour Doppler ultrasonography in evaluating renal obstruction; in particular, partial or intermittent obstruction cause minimum hemodynamic changes in patients with renal colic. Sensitivity of colour Doppler ultrasonography to detect obstruction decreases following medical treatment with NSAID and increases following hydration and diuretics administration. Diuretic ultrasound, colour Doppler evaluation of ureteral jets and evaluation of the twinkling artefact of stones are useful imaging techniques as well. Tissue harmonic imaging is a new imaging technique available in most latest generation US equipments. Evaluation of the kidney and of the urinary tract improves using this technique due to artefact reduction and increased contrast resolution.

Digital vs conventional radiography: cost and revenue analysis.

The objective of this study was to analyse and compare the operating and investment costs of two radiographic systems, a conventional and a digital one, and to evaluate the cost/revenue ratio of the two systems. The radiological activity over 1 year for chest and skeletal exams was evaluated: 13,401 chest and 7,124 skeletal exams were considered. The following parameters of variable costs were evaluated: the difference between variable proportional costs of the two technologies, the effective variable cost of any size film, including the chemicals, and for different sizes of digital film, variable costs of chest plus skeletal exams performed with the two techniques. Afterwards the economical effect was considered taking into account depreciation during a time of utilization ranging between 8 and 4 years. In the second part of the analysis the total cost and the revenues of the two technologies were determined. The comparison between the digital and conventional systems has shown the following aspects: 1. Digital radiography system has a much higher investment cost in comparison with the conventional one. 2. Operating costs of digital equipment are higher or lower depending on the film size used. Evaluating chest X-ray we reach a breakeven point after 1 year and 10,000 exams only if displayed over 8 x 10-in. film and after 30,000 if displayed over a 11 x 14-in. film. 3. The total cost (variable cost, technology cost, labour cost) of digital technology is lower than that of the conventional system by 20 % on average using 8 x 10-in. film size. 4. Digital technology also allows lesser film waste and lesser film per exam

Type II atrial flutter interruption with transesophageal pacing: use of propafenone and possible change of the substrate.

Type II atrial flutter (AFII) is an arrhythmia which usually cannot be interrupted by atrial pacing: the underlying mechanism is considered to be a leading circle without an excitable gap. We investigated whether the administration of propafenone, an antiarrhythmic drug, which primarily decreases conduction velocity, has a beneficial effect on AFII interruption using transesophageal pacing. Twelve patients with an AFII were randomized into 2 groups in which pacing was performed without treatment (group A) or two hours after the administration of 600 mg of oral propafenone (group B). Sinus rhythm was attained in 0 of 6 patients in group A and in 4 of 6 patients in group B (P < 0.05). The baseline mean cycle length was the same in both groups (175 +/- 7 (A) vs 168 +/- 8 ms (B); it lengthened significantly after the administration of propafenone (219 +/- 33 vs 168 +/- 8 ms; P < 0.05). Propafenone did not significantly lengthen the cycle in the two patients in whom interruption of the arrhythmia was impossible. Our data show that propafenone has a facilitating effect on atrial pacing only when it significantly prolongs the cycle length of the arrhythmia, possible expression of a conversion of AFII into type I, with an anatomical substrate and an excitable gap allowing arrhythmia capture and interruption. In the two patients in whom sinus rhythm was not restored, the absence of a direct dependence of the cycle length on the change in conduction velocity induced by propafenone may be explained by the persistence of a functionally determined circuit, resistant to atrial pacing.

[Facilitating effect of propafenone pretreatment in the interruption of atrial flutter by transesophageal pacing]. / Effetto facilitante del pretrattamento con propafenone nell'interruzione del flutter atriale mediante stimolazione transesofagea.

Transesophageal atrial pacing is effective in the interruption of atrial flutter, and being simple and minimally invasive, is easily performed even on outpatients. The influence of antiarrhythmic drugs on this procedure is controversial. We investigated whether the administration of oral propafenone may facilitate the procedure. Thirty patients with type I atrial flutter were randomized into two groups in which transesophageal pacing was attempted, respectively, without treatment (Group A) and after oral administration of propafenone 600 mg (Group B). Transesophageal pacing was effective in interrupting atrial flutter in 53% (8/15) of patients in Group A and in 85% (13/15) of patients in Group B. A significant lengthening of the flutter cycle was observed in patients treated with propafenone (261 +/- 23 vs 217 +/- 25 ms, p < 0.01). Sinus rhythm resumed at a shorter paced cycle in patients of Group A (166 +/- 13 vs 187 +/- 14 ms, p < 0.01). The transesophageal threshold for stable atrial capture was significantly lower in Group A (20.5 +/- 0.2 vs 23.3 +/- 1.2 mA, p < 0.01). In no patient the threshold for atrial capture was higher than the pain threshold. We did not observe abrupt enhancement of atrioventricular conduction. We can conclude that propafenone is effective and safe when used with transesophageal pacing in the termination of atrial flutter. The depressing effect of the drug on intraatrial conduction and the possible stabilizing effect on the reentry circuit appear to be outweighed by the positive effect of propafenone on the excitable gap of the circuit, facilitating its capture and account for the beneficial effect of the drug on arrhythmia termination.

Atrial flutter termination by overdrive transesophageal pacing and the facilitating effect of oral propafenone.

Transesophageal overdrive atrial pacing is effective and safe for atrial flutter termination. The influence of antiarrhythmic drug therapy on this procedure is controversial. In this study, we investigated whether oral propafenone may facilitate this procedure. Thirty patients with type I atrial flutter were randomized into 2 groups in which transesophageal pacing was attempted: group A, without treatment; and group B, after oral administration of propafenone 600 mg. Transesophageal pacing was effective in interrupting atrial flutter in 53% of patients (8 of 15) in group A and in 87% of patients (13 of 15) in group B. A significant lengthening of the flutter cycle was observed with respect to the baseline in patients given propafenone (261 +/- 23 vs 217 +/- 25, p < 0.01). Sinus rhythm resumed at a shorter paced cycle in group A patients (166 +/- 13 vs 187 +/- 14 ms, p < 0.01). The transesophageal threshold for stable atrial capture was significantly lower in group A (20.5 +/- 0.2 vs 23.3 +/- 1.2, p < 0.01). In no patient was the threshold for atrial capture higher than the pain threshold. We did not observe abrupt enhancement of atrioventricular conduction. We conclude that propafenone is effective and safe when used with transesophageal pacing in the termination of atrial flutter. The slowing effect of the drug on intraatrial conduction and the possible stabilizing effect on the reentry circuit appear to be outweighed by the positive effect of propafenone on the excitable gap of the circuit, facilitating its capture and accounting for the beneficial effect of the drug on arrhythmia termination.

Changes in circulating norepinephrine with hemofiltration in advanced congestive heart failure.

In congestive heart failure (CHF), hemofiltration is associated with an obvious decrease in circulating norepinephrine. This method was used for investigating the mechanisms whereby plasma norepinephrine is increased in chronic CHF. In 23 cases of advanced CHF, hemofiltration (2,983 +/- 1,228 ml) lowered plasma norepinephrine by 515 +/- 444 pg/ml. This effect was prompt, persisted or became greater in the next 24 hours. It was not associated with significant changes in cardiac output, aortic pressure or systemic vascular resistance. It did not appear to depend on variations in parameters related to the sympathetic activity, such as plasma renin, right atrial, wedge pulmonary artery and renal perfusion pressures, and was independent of duration and amount of hemofiltration. These observations did not support the concept that the norepinephrine decrease was the main consequence of a neural sympathetic inhibition. Hemofiltration increased diuresis by 606 +/- 415 ml; changes were prompt and correlated inversely (r = -0.7; p less than 0.01) with those in plasma norepinephrine. The same unknown mechanism of the increased urinary output might potentiate the norepinephrine removal from the blood by the kidney, or hemofiltration and the augmented diuresis might result in a regression of congestion of lungs and kidneys, leading to an improved extraction of norepinephrine. In CHF, a relation may exist between fluid retention and norepinephrine and in advanced stages, circulating norepinephrine, although strikingly increased, is devoid of important cardiovascular effects. At these stages, plasma norepinephrine is probably unreliable as an index of the sympathetic neural activity.

[Neurohumoral changes induced by hemofiltration in congestive heart failure: physiopathological inferences]. / Modificazioni neuroumorali indotte dalla emofiltrazione nello scompenso congestizio: inferenze fisiopatologiche.

Hemofiltration is a method suitable for rapid substraction of plasma water that generally allows reduction of circulating levels of norepinephrine. Using that non-pharmacological approach we investigated the mechanisms involved in the metabolism of the hormone as well as the hemodynamic correlates of a prompt and great fall of the sympathetic neurotransmitter in patients with chronic refractory congestive heart failure (CHF). In 23 patients with CHF, hemofiltration of 2983 +/- 1228 ml of plasma water (in 5 +/- 2 hours of treatment) increased urinary output by 606 +/- 415 ml in the day of the procedure as well as sodium excretion by 53 +/- 38 mEq/24 h; simultaneously, a mean fall in plasma norepinephrine concentration by 515 +/- 444 pg/ml was observed. These effects were prompt and persisted or even rose in the next 24 and 48 hours, not being related to changes in plasma renin activity, right atrial, wedge pulmonary artery and renal perfusion pressures and to the amount and duration of hemofiltration. Our data did not clarify the mechanism involved in the increase of the diuresis and for its coupling with the fall in plasma norepinephrine. Nevertheless, we found a strong and statistically significant correlation (r = 0.7; p less than 0.01) between percent changes from baseline values of norepinephrine and diuresis. It is therefore suggested that the same, still unknown, mechanism which increased urinary output also potentiated norepinephrine removal by the kidney: or that water reabsorption from extravascular spaces (triggered by hemofiltration and continued by increased diuresis) resulted in regression of organ congestion leading to an improved clearance of norepinephrine by different organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolated ultrafiltration in cardiogenic pulmonary edema.

Twenty patients (ten with mitral and/or aortic valve disease and ten with ischemic heart disease, all in the New York Heart Association class IV, aged between 18 and 74 yr, with cardiogenic pulmonary edema unresponsive to drug treatment) were treated with polysulphone membrane ultrafiltration (UF) in a veno-venous circuit. All patients had dyspnea, pulmonary rales, hypoxemia, tachycardia, hypotension, overhydration, radiologic evidence of engorged pulmonary vasculature, and Kerley-B lines. Systemic and pulmonary arterial pressures, cardiac output (by thermodilution), and intrapulmonary shunt fraction (Qsp/Qt) were determined and chest x-ray was obtained at the beginning and the end of UF. Average duration of the treatment was 150 +/- 28 min; UF volume averaged 3000 +/- 170 ml. UF reduced the Qsp/Qt by 58% from control condition, and did not significantly affect hemodynamic variables. Chest x-rays documented clearing of alveolar edema and venous congestion. These changes were associated with unequivocal clinical improvement and no mechanical ventilation was necessary to improve gas exchange. Short-term fluid subtraction did not result in undesired circulatory alternations. Because the ultrafiltrate composition is similar to plasmatic fluid, no modification in the plasma osmolarity was detected. In conclusion, UF may be considered an effective tool for the treatment of acute pulmonary edema refractory to drug therapy, as an alternative to mechanical ventilation, and as a remedy for excessive extravascular lung water.