Biomedical subjects

G M Deeb

Publications and source records attributed to G M Deeb.

At least 55 records · Page 3Linked to original sources

PubMed1996

Three-dimensional gadolinium-enhanced MR angiography of the thoracic aorta.

OBJECTIVE: Our objective was to evaluate image quality and preliminary clinical experience with three-dimensional gadolinium-enhanced MR angiography of the thoracic aorta. SUBJECTS AND METHODS: Ninety patients with suspected thoracic aorta pathology underwent 97 MR examinations at 1.5 T with a 4-min, three-dimensional spoiled gradient-echo techniques. Gadolinium infusion was timed for maximum arterial contrast during acquisition of the central portion of K-space. No ECG gating or breath-holding was used. All MR examinations were evaluated retrospectively for intravascular signal-to-noise ratio (SNR). In 30 of the 90 patients, results from surgery (n = 11), angiography (n = 12), or both (n = 7) were available. Four radiologists who were unaware of the angiographic or surgical findings assessed each of these 30 examinations for three types of pathology: dissection, coarctation, or aneurysm. The observers also assessed aortic branch vessel patency and vascular anomalies in the 19 patients who had angiographic correlation. RESULTS: Image quality (determined as SNR) was highest in the aortic arch, upper descending thoracic aorta, and upper abdominal aorta. We saw a small reduction in the SNR in the ascending aorta and lower descending thoracic aorta (p < .0001), attributable to cardiac and respiratory motion. Image quality was not affected by slow flow. MR imaging correctly diagnosed pathology in all 30 patients with angiographic or surgical correlation, including eight dissections, three coarctations, and 10 aneurysms. The type of the dissection was correctly determined in all eight patients. Stenoses of major branch vessel origins were detected with a sensitivity of 90% (95% bayesian confidence interval, 99-63%) and a specificity of 96% (95% bayesian confidence interval, 99-89%) in the 19 patients with angiographic correlation. Five vascular anomalies, including an aberrant right subclavian artery, a bovine arch, and three accessory renal arteries, were correctly identified. CONCLUSION: Three-dimensional gadolinium-enhanced MR angiography has the potential to accurately diagnose aortic dissection, coarctation, and aneurysm. It does not require ECG gating or breath-holding and thereby extends the diagnostic utility of MR imaging for the thoracic aorta.

Adolescent↗

PubMed1995

Accuracy of intraoperative transesophageal echocardiography for estimating the severity of functional mitral regurgitation.

Although intraoperative transesophageal echocardiography (TEE) is used to guide mitral valve reconstructive procedures, the effects of hemodynamic alterations accompanying general anesthesia on mitral regurgitation (MR) are unknown. This study was performed to evaluate the effect of general anesthesia on MR jet size using TEE with color Doppler imaging in patients undergoing mitral valve surgery. Matched preoperative TEEs performed with the patient under intravenous conscious sedation, and intraoperative studies performed with the patient under general anesthesia were retrospectively reviewed in 46 patients undergoing mitral valve surgery. Patients were divided into groups based on etiology of MR, including 21 patients with myxomatous degeneration and leaflet flail, 19 patients with structurally normal leaflets and functional regurgitation due to abnormal leaflet coaptation, and 6 patients with rheumatic mitral disease. On both preoperative and intraoperative studies, regurgitation was quantified using maximal jet area and jet diameter at the vena contracta on color flow Doppler. Patients with leaflet flail and patients with functional MR had similar measures of regurgitation severity on preoperative imaging. On intraoperative imaging, regurgitant jet size was unchanged compared with preoperative studies among patients with leaflet flail (jet diameter 1.04 +/- 0.26 vs 1.10 +/- 0.28 cm, area 9.8 +/- 4.5 vs 10.1 +/- 5.2 cm2 on preoperative studies), although jet size decreased significantly in patients with functional MR (jet diameter 0.79 +/- 0.33 vs 1.10 +/- 0.29 cm [p < 0.001], area 5.7 +/- 3.5 vs 10.0 +/- 3.8 cm2 [p < 0.001] on preoperative studies). These findings were not accounted for by variation in heart rate, blood pressures, echocardiographic instrumentation, or Doppler Nyquist limit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Pattern of injury and the role of neutrophils in reperfusion injury of rat lung.

Using a rat lung model, we sought to characterize the time course for ischemia-reperfusion injury and the role of neutrophils in the development of injury. Adult male Long-Evans rats underwent left thoracotomy with dissection and clamping of the left pulmonary artery, bronchus, and vein for 90 min, resulting in complete left lung ischemia. The lungs were then ventilated and reperfused for up to 4 hr. Time-matched sham animals underwent the identical thoracotomy and hilar dissection, but the lungs were not rendered ischemic. Using vascular permeability of 125I-labeled bovine serum albumin as a measure of reperfusion injury, a bimodal pattern of injury was observed. Compared to sham controls, animals undergoing ischemia-reperfusion demonstrated a significant early phase of lung injury at 30 min of reperfusion (P < 0.0001), followed by partial recovery. A second peak of lung injury was noted after 4 hr of reperfusion (P < 0.001). Myeloperoxidase activity in reperfused lung tissue, a measure of neutrophil sequestration, increased during the reperfusion time course. To determine the role of neutrophils in the development of lung reperfusion injury, additional animals undergoing the identical ischemia-reperfusion protocol received either rabbit anti-rat neutrophil serum or preimmune serum the day prior to operation. Profound neutropenia (< 75/mm3 blood) was confirmed by differential leukocyte counts. Neutropenia had no protective effect against microvascular permeability at 30 min of reperfusion, but there was a significant reduction in lung injury at 4 hr (P < 0.005). We conclude that, during lung ischemia-reperfusion, there is a bimodal pattern of injury, consisting of both neutrophil-independent and neutrophil-mediated events.

Animals↗

PubMed1995

Disparate effects of nitric oxide on lung ischemia-reperfusion injury.

BACKGROUND: Inhaled nitric oxide (.NO) has been found to be a potent pulmonary vasodilator. We assessed whether .NO, through this function or others, could alleviate lung reperfusion injury. METHODS: Rats underwent thoracotomy, with clamps used to create left lung ischemia. After 90 minutes of ischemia, clamps were released, permitting reperfusion for either 30 minutes or 4 hours. Additional animals received inhaled .NO via the ventilator to determine its effects on reperfusion injury. RESULTS: Lung injury, measured by increased vascular permeability using iodine-125-labeled bovine serum albumin leakage, was significantly increased in ischemic-reperfused animals compared with time-matched shams not undergoing ischemia. Inhaled .NO delivered at the start of reperfusion worsened injury at 30 minutes but was protective at 4 hours. The increased injury could be avoided either by delaying .NO for 10 minutes or by treating the animals with superoxide dismutase before reperfusion. .NO reversed postischemic pulmonary hypoperfusion at 4 hours, as measured by labeled microspheres. Lung neutrophil content was significantly reduced at 4 hours in .NO-treated animals. CONCLUSIONS: .NO is toxic early in reperfusion, due to its interaction with superoxide, but is protective at 4 hours of reperfusion, due to reversal of postischemic lung hypoperfusion and reduction of lung neutrophil sequestration.

Administration, Inhalation↗

PubMed1995

Early outcome of mitral valve reconstruction in patients with end-stage cardiomyopathy.

Uncontrollable severe mitral regurgitation is a frequent complication of end-stage cardiomyopathy, significantly contributing to heart failure in these patients, and predicts a poor survival. Although elimination of mitral valve regurgitation could be most beneficial in this group, corrective mitral valve surgery has not been routinely undertaken in these very ill patients because of the presumed prohibitive operative mortality. We studied the early outcome of mitral valve reconstruction in 16 consecutive patients with cardiomyopathy and severe, refractory mitral regurgitation operated on between June 1993 and April 1994. There were 11 men and five women, aged 44 to 78 years (64 +/- 8 years) with left ventricular ejection fractions of 9% to 25% (16% +/- 5%). Preoperatively all patients were in New York Heart Association class IV, had severe mitral regurgitation (graded 0 to 4+ according to color flow Doppler transesophageal echocardiography) and two were listed for transplantation. Operatively, a flexible annuloplasty ring was implanted in all patients. Four patients also had single coronary bypass grafting for incidental coronary disease. In four patients the operation was performed through a right thoracotomy because of prior coronary bypass grafting, and four patients also underwent tricuspid valve reconstruction for severe tricuspid regurgitation. No patient required support with an intraaortic balloon pump. There were no operative or hospital deaths and mean hospital stay was 10 days. There were three late deaths at 2, 6, and 7 months after mitral valve reconstruction, and the 1-year actuarial survival has been 75%. At a mean follow-up of 8 months, all remaining patients are in New York Heart Association class I or II, with a mean postoperative ejection fraction of 25% +/- 10%. There have been no hospitalizations for congestive heart failure, and a decrease in medications required has been noted. For patients with cardiomyopathy and severe mitral regurgitation, mitral valve reconstruction as opposed to replacement can be accomplished with low operative and early mortality. Although longer term follow-up is mandatory, mitral valve reconstruction may allow new strategies for patients with end-stage cardiomyopathy and severe mitral regurgitation, yielding improvement in symptomatic status and survival.

Adult↗

PubMed1995

Retrograde cerebral perfusion during hypothermic circulatory arrest reduces neurologic morbidity.

Hypothermic circulatory arrest has become an accepted technique for a variety of cardiac and complex aortic operations. However, prolonged periods (> 45 min) of hypothermic circulatory arrest in older patients is associated with marginal cerebral protection and an increased incidence of adverse neurologic events. In an effort to minimize such morbidity, we used a technique of retrograde cerebral perfusion with continuous monitoring of cerebral hemoglobin oxygen saturation during hypothermic circulatory arrest in 35 patients who underwent thoracic aortic operations or resection of intracardiac tumor. There were 27 men and 8 women (mean age 60 years, range 21 to 83 years). Sixteen patients had acute dissection, 6 had contained rupture of a thoracic aortic aneurysm, 10 had either a chronic dissection or aneurysm, and 3 had hypernephromas extending into the heart. Six patients underwent root replacement by means of an open technique for their distal anastomosis, 7 underwent root and partial arch replacement, 12 had root and total arch replacement, 7 had total arch replacement, and 3 had resection of tumor in the heart and retrohepatic vena cava. Seven patients had simultaneous coronary artery bypass grafting, 3 had replacement of one of the arch vessels, and 2 patients had a cesarean section. Sixteen cases were emergency, 6 urgent, and 13 elective. Nine (26%) were reoperations. Thirty-four patients underwent the procedure via a median sternotomy and one patient through a posterolateral thoracotomy. The mean retrograde cerebral perfusion time was 63 minutes (range 35 to 128 minutes), with 30 (86%) patients having more than 45 minutes, 12 (34%) having more than 65 minutes, and 4 (11%) having more than 90 minutes. There was 1 operative death caused by a preoperative myocardial infarction from an aortic dissection, and there were 2 late deaths (multiple organ failure and ruptured total aortic aneurysm). One patient had a stroke with a residual right hemiplegia and a pronounced aphasia. There were no other significant neurologic events or reoperations for bleeding. The average length of stay for patients having elective operations was 11 days and for those having emergency operations, 27 days. At a mean follow-up of 6 months all surviving patients (91%) are well. Hypothermic circulatory arrest is a relatively simple technique that provides a bloodless field and good visualization without the need for aortic crossclamps. Moreover, retrograde cerebral perfusion with continuous monitoring of cerebral oxygen saturation extends the "safe" time for hypothermic circulatory arrest, allowing ample opportunity to perform complicated cardiac and aortic operations with reduced risk of adverse neurologic events.

Aortic Dissection↗

PubMed1995

Stenosis of the central airways: evaluation by using helical CT with multiplanar reconstructions.

PURPOSE: To assess the accuracy of helical computed tomography (CT) with multiplanar reconstructions (MPRs) in the evaluation of stenoses of the central airways. MATERIALS AND METHODS: Thin-section axial CT and helical CT with MPRs were used to examine the central tracheobronchial tree for the presence of stenosis in 27 patients who underwent lung transplantation and 17 nontransplantation patients. The findings from these modalities were then compared with the findings obtained at conventional tomography and bronchoscopy, when available. RESULTS: Axial CT alone was 91% accurate in depicting stenosis, CT with MPRs was 94% accurate, and conventional tomography was 89% accurate in the evaluation of bronchial anastomosis in transplant recipients. CT and CT scans with MPRs were each 91% accurate in depicting stenosis in nontransplantation patients; the single false-negative finding showed focal tracheomalacia at bronchoscopy. CONCLUSION: CT with MPRs may be more accurate than thin-section axial CT in the demonstration of mild stenosis, the length of a stenosis, and horizontal webs.

Anastomosis, Surgical↗

PubMed1995

Cardiopulmonary exercise testing following allogeneic lung transplantation for different underlying disease states.

OBJECTIVES: To assess the exercise response to single lung transplantation in chronic airflow obstruction (CAO), idiopathic pulmonary fibrosis (IPF), and pulmonary vascular disease (PVD) vs double lung transplantation at well-defined time points after transplantation, and to define the change in exercise response in SLT and DLT over the first year after transplantation. DESIGN: Prospective study. SETTING: Tertiary referral hospital. PATIENTS: Fourteen stable SLT recipients (6 with CAO, 4 with IPF, 4 with PVD) and 11 stable DLT recipients. MEASUREMENTS: Spirometry, lung volumes, diffusion lung capacity for carbon monoxide (DLco) and MVV measured prior to exercise at 3 months (n = 25) then at 3-month intervals up to a maximum of 12 months post-transplantation (n = 18 [12 SLT and 6 DLT]). Symptom-limited cardiopulmonary exercise tests at same time points (n = 25 at 3 months, n = 18 [12 SLT and 6 DLT] at 3-month intervals up to 12 months). Breathlessness was estimated by visual analogue scale prior to exercise and at peak exercise. RESULTS: At 3 months, FEV1 percent predicted was lower for SLT-CAO and SLT-IPF vs DLT (p < or = 0.05). Mean FEV1/FVC was lower for SLT-CAO vs all other groups (p < or = 0.05). The FVC, MVV, and DLco/VA were similar for all groups. The TLC and RV were higher for the SLT-CAO group compared with all others. The TLC was lower for SLT-PVD compared with DLT. Exercise responses were similar in all groups studied without a statistically significant difference in achieved VO2, work rate, O2 pulse, anaerobic threshold, heart rate response, respiratory rate, VE/MVV, and VT/VC. The change in O2 saturation during exercise was the least in recipients of DLT. Maximal achieved VO2 rose from 3 to 6 months after SLT but dropped by 9 to 12 months after transplantation. Maximal achieved VO2 trended up from 3 to 6 months after DLT but dropped by 9 to 12 months after transplantation. Maximal achieved work rate rose in both SLT and DLT from 3 to 9 to 12 months after transplantation. There was no significant difference in breathlessness at rest and peak exercise measured between recipients of SLT or DLT. CONCLUSIONS: Minor differences in pulmonary function and change in O2 saturation occur between recipients of SLT and DLT during the first posttransplant year. These differences are most pronounced when comparing SLT-CAO with DLT. However, there is no significant difference in exercise capacity between SLT for CAO, IPF, PVD, and DLT. The rise in maximum achieved VO2 over the first 6 months after transplantation may reflect the effects of exercise training and should be taken into account when examining aerobic response after transplantation.

Anaerobic Threshold↗

PubMed1994

Emergent percutaneous cardiopulmonary bypass in patients having cardiovascular collapse in the cardiac catheterization laboratory.

Percutaneous cardiopulmonary bypass (PCB) was instituted in 30 initially stable patients who developed either cardiac arrest refractory to resuscitation (n = 7) or cardiogenic shock (mean arterial blood pressure < 50 mm Hg unresponsive to fluid resuscitation or vasopressors) (n = 23) after a catheterization laboratory complication. Events leading to collapse included abrupt closure during percutaneous transluminal coronary angioplasty (PTCA) (n = 22), complications from diagnostic cardiac catheterization (n = 6), left ventricular perforation during mitral valvuloplasty (n = 1), and right ventricular perforation during pericardiocentesis (n = 1). PCB was initiated within 20 minutes of cardiovascular collapse in 83% of patients (arrest: 21 +/- 13 minutes [range 10 to 50]; and shock: 17 +/- 6 minutes [range 10 to 30]). Mean arterial blood pressure increased on PCB from 0 to 56 mm Hg in patients with cardiac arrest and from 37 to 63 mm Hg in those with cardiogenic shock at mean PCB flow rates of 2.5 to 5.0 liters/min. Subsequent therapy on PCB included emergent cardiac surgery (n = 14), PTCA (n = 13) and medical therapy (n = 3). Six patients (20%) survived to hospital discharge (3 with cardiac surgery, 2 with PTCA, and 1 with medical therapy). All 7 patients with refractory cardiac arrest died despite further interventions on PCB, whereas 6 of 23 (26%) with cardiogenic shock survived to hospital discharge. Thus, in response to cardiovascular collapse in the catheterization laboratory, PCB does not salvage patients who do not regain a stable cardiac rhythm. PCB can stabilize patients who develop cardiogenic shock for further interventions which are lifesaving in only a minority of patients.

Aged↗

PubMed1994

Rigid internal fixation of the sternum in postoperative mediastinitis.

OBJECTIVE: The current standard treatment of mediastinitis following median sternotomy is radical sternal débridement and obliteration of anterior mediastinal dead space with muscle or omental flaps. This report describes and reviews our experiences with a new technique of sternal salvage based on osseous quantitative bacteriologic assessment and rigid fixation in patients with postoperative mediastinitis. DESIGN: A retrospective review of 29 patients treated with sternal rigid internal fixation. SETTING: Two tertiary care academic medical centers in Chicago, Ill, and Ann Arbor, Mich. PATIENTS: Patients with postoperative mediastinitis following median sternotomy who underwent rigid internal fixation of retained sternum. INTERVENTION: Following débridement, quantitative bacteriologic assessment and sternal vascularity were assessed. Sternal segments with good vascularity and in bacteriologic balance were anatomically reduced and rigidly fixed to each other with titanium miniplates in 24 patients with postoperative mediastinitis. Five of the 29 patients, at high risk for mediastinitis, underwent rigid internal fixation immediately after their cardiac procedure. MAIN OUTCOME MEASURES: Resolution of infection, wounds remaining closed, and stable sternums. RESULTS: Bony union was obtained in 27 (93%) of 29 patients. The postoperative hospital stay ranged from 5 to 84 days, with a mean stay of 17 days and a median stay of 7 days. Length of stay was directly related to pulmonary function, which correlated with preoperative intubation status. CONCLUSIONS: Radical sternal débridement may not be necessary in all patients with postoperative mediastinitis following median sternotomy. Sternal salvage can safely and reliably be performed with a combination of clinical assessment of vascularity and osseous quantitative bacteriologic assessment. Anatomic reduction of the viable sternal segments is possible even in severely osteoporotic bone.

Adolescent↗

PubMed1994

Selective lung or heart-lung transplantation for pulmonary hypertension associated with congenital cardiac anomalies.

Fixed pulmonary hypertension has been a contraindication to correction of congenital heart defects. Beginning in February 1991, we pursued a policy of performing single-lung transplantation with intracardiac repair for selected patients with this physiology, reserving heart-lung transplantation for those with unreconstructable heart disease. Of 7 patients treated under this protocol, 5 underwent single-lung transplantation and intracardiac repair. The cardiac anomalies included complete atrioventricular canal (1), aortopulmonary window (1), atrial septal defect (1), and ventricular septal defect (2). One patient died perioperatively. All 4 patients surviving operation remained alive through the first postoperative year, but 3 died 13, 17, and 22 months after operation. Two other patients with pulmonary hypertension (1 with tricuspid atresia, 1 after failed Mustard procedure) received a heart-lung transplant and are well 15 and 18 months after operation. This experience demonstrates that selected patients with major intracardiac defects and pulmonary hypertension may have good early results after cardiac repair and single-lung transplantation, but that long-term results are considerably less favorable.

Adolescent↗

PubMed1994

Extracorporeal life support after heart or lung transplantation.

Extracorporeal life support (ECLS) has been used in 10 patients after heart (5 patients), lung (3 patients), and heart-lung (2 patients) transplantation. The age range was 7 months to 55 years. Cardiopulmonary failure leading to institution of ECLS was due to acute postoperative organ malfunction in 4 patients (2 survived), subacute organ malfunction in 3 patients (none survived), and late rejection or infection in 3 patients (2 survived). Neurologic complications occurred in 3 patients (1 survived) and bleeding, in 5 patients (2 survived). Six patients (60%) were successfully weaned from ECLS, and 4 (40%) survived to leave the hospital. Survival was associated with younger age, shorter duration of ECLS, and longer interval from operation to initiation of ECLS but not to reason for initiating ECLS. Extracorporeal life support is feasible for sustaining both adults and children after heart, lung, or heart-lung transplantation. Best results were obtained in patients with conditions that, in retrospect, were treatable and reversible within days. More experience is needed to predict preoperatively which patients will benefit most from ECLS.

Adolescent↗

PubMed1994

Simultaneous traumatic ascending and descending thoracic aortic rupture.

A case of a 56-year-old male blunt trauma victim with combined simultaneous ascending and descending thoracic aortic rupture is presented. He was successfully treated with immediate operation for the ascending aortic rupture and a delayed approach, with nonoperative stabilization and later repair, due to poor pulmonary status and a question in diagnosis, for the descending aortic rupture.

Aorta↗

PubMed1994

P450 3A activity and cyclosporine dosing in kidney and heart transplant recipients.

Interpatient differences in the kinetics of cyclosporine appear to result in part from interindividual differences in the catalytic activity of an enzyme termed P450 3A. We investigated the relationship between P450 3A activity, as measured by the erythromycin breath test (ERMBT), and the appropriate stable daily dose of cyclosporine as currently determined by physicians at our institution. The ERMBT was administered to kidney and heart allograft recipients who had attended at least two monthly clinic visits without having their daily cyclosporine dose changed. There was a significant positive correlation between the ERMBT result and the daily cyclosporine doses (in milligrams per kilogram) in both the heart (r = 0.68; p = 0.04; n = 9) and kidney (r = 0.68; p = 0.03; n = 10) recipients. To confirm our findings, we prospectively administered the ERMBT on multiple occasions to 20 patients who were undergoing kidney transplantation. Although the transplant physicians were blinded to the ERMBT results, the test predicted the stable daily doses of cyclosporine that they ultimately prescribed to the patients (r = 0.54; p = 0.015). When data from all 39 patients were pooled and subjected to multiple regression analysis, the ERMBT was the only variable examined that significantly correlated with the stable daily cyclosporine dose (r = 0.63; p < 0.001; n = 39). In the 20 patients prospectively studied, the prescribed daily dose of cyclosporine generally decreased during the months after surgery and the percentage changes in cyclosporine daily dose correlated with changes in P450 3A activity during this period (r = 0.47; p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

High-resolution CT detection of lacerations in the transplanted lung after transbronchial biopsy.

Relatively large tissue samples may be obtained from the lung with the "Alligator" biopsy forceps. We report the radiographic and high-resolution computed tomography (HRCT) appearances of six pulmonary lacerations in the transplanted lungs of three asymptomatic patients after transbronchial biopsy with this large caliber biopsy forceps. All patients had undergone transbronchial biopsy from 4 to 10 days before HRCT that was performed as part of routine surveillance after transplantation. The site and histopathologic findings of lung biopsies and negative microbiologic studies on bronchoalveolar washings correlated accurately with each pulmonary lesion seen. Laceration size varied from 9 to 20 mm (mean 14 mm) on HRCT. A thickened wall or surrounding alveolar reaction related to bronchoalveolar lavage or biopsy-induced hemorrhage was seen in five lesions. These simulated the appearance of lung abscess or invasive fungal disease. Only nonspecific alveolar opacities were noted on chest radiographs. The Alligator biopsy forceps may cause pulmonary lacerations in transplanted lungs that are detectable on HRCT but not on chest radiographs. Differentiation from opportunistic infection by CT criteria alone is difficult in these immunocompromised patients. CT studies in this population should be performed prior to transbronchial biopsy whenever possible.

Adult↗

PubMed1994

Aortic cobwebs: an anatomic marker identifying the false lumen in aortic dissection--imaging and pathologic correlation.

PURPOSE: To describe and estimate the frequency of fibroelastic cords or bands projecting from the false lumen wall ("aortic cobwebs") in acute and chronic dissections. MATERIALS AND METHODS: Pathologic specimens (n = 23), routine magnetic resonance (MR) images (n = 27), and intravascular (n = 5) and transesophageal (n = 3) ultrasound (US) images from 43 patients with aortic dissection were reviewed, and the presence and configuration of cobwebs were noted. RESULTS: Aortic cobwebs usually bridge the junction of the dissection flap with the outer wall of the false lumen (the line of dissection) but occasionally project like small tendrils from the false lumen wall remote from the line of dissection. Cobwebs were found in 17 of 23 pathologic specimens and on six of 27 MR images, two of five intravascular US scans, and one of three transesophageal US scans. CONCLUSION: Aortic cobwebs most likely represent residual ribbons of media that have been incompletely sheared from the aortic wall during the dissection process. As such, they can serve as an anatomic marker of the false lumen. They are occasionally seen on routine aortic images and may, therefore, prove useful for orientation during percutaneous or surgical interventional procedures to relieve ischemic complications of aortic dissection.

Aortic Dissection↗

PubMed1994

Relation of regional function, perfusion, and metabolism in patients with advanced coronary artery disease undergoing surgical revascularization.

BACKGROUND: Imaging of myocardial glucose metabolism using [18F]fluorodeoxyglucose (FDG) with positron emission tomography (PET) has been proposed for identification of tissue viability in patients with advanced coronary artery disease. This study was designed to evaluate the predictive value of flow and metabolic imaging for functional recovery after revascularization in myocardial segments of varying degrees of dysfunction. METHODS AND RESULTS: Thirty-seven patients (mean age, 59 +/- 11 years) with coronary artery disease and impaired left ventricular function (ejection fraction, 34 +/- 10%) were studied with PET using FDG and [13N]ammonia before surgical coronary revascularization (3 +/- 1 grafts per patient). Tissue was scintigraphically characterized as normal, nonviable (concordant reduction of perfusion and FDG uptake), viable without discordance of perfusion and metabolism (mildly reduced perfusion and metabolism), or ischemically compromised (mismatch of reduced perfusion and maintained FDG uptake). Functional outcome was assessed by serial radionuclide ventriculography before and at 13 +/- 13 weeks (median interval of 8 weeks) after coronary revascularization. Preoperatively impaired regional wall motion improved significantly in ischemically compromised (mismatch) revascularized segments but not in nonviable myocardium or in viable myocardium without discordance of perfusion and metabolism. The negative predictive value of PET for functional recovery was 86%, whereas the positive predictive value in revascularized regions ranged from 48% to 86% depending on severity of baseline wall motion abnormalities. CONCLUSIONS: PET identifies metabolically active tissue, which benefits from revascularization. Although the negative predictive value of PET for recovery was high, functional improvement of viable but ischemically compromised tissue was less frequent than previously reported. The predictive value of PET was highest in left ventricular segments with severe dysfunction and a mismatch or reduced perfusion but preserved metabolism. Integration of PET, angiographic, and functional data is necessary for the optimal selection of patients with advanced coronary artery disease and impaired left ventricular function for revascularization.

Adult↗

PubMed1994

Limitations of spirometry in detecting rejection after single-lung transplantation.

Pulmonary function testing has been extensively studied in the heart-lung transplant (HLT) population and has been advocated as a screening test for rejection or infection; however, few data are available in the single-lung transplant (SLT) population. The effect of acute episodes of infection, rejection, and bronchiolitis on the pulmonary function of 30 SLT patients with varying underlying disease states was prospectively evaluated. The native disease process was obstructive in 17 (SLT-OBS), restrictive in six (SLT-IPF), and pulmonary vascular in seven (SLT-PVD). Rejection was associated with a drop in FVC from 71 +/- 15 to 62 +/- 14% of predicted, with a significant drop seen in all three subgroups. Statistically significant drops in FEV1 were also seen in the SLT-OBS and SLT-PVD subgroups but not in the SLT-IPF subgroup. A drop in FEV25-75% was seen only in SLT-PVD. The greatest fall in FVC, FEV1, and FEF25-75% was seen with bronchiolitis, followed by acute rejection. The sensitivity and specificity of spirometry as a predictor of infection or rejection were significantly lower than those previously reported for HLT, with SLT-PVD having the most and SLT-OBS the least clinically useful values. We conclude that a fall in spirometry is seen in infection and rejection in SLT and that the underlying disease state has a significant influence on the diagnostic utility of specific spirometric indices.

Adult↗