The effect of helical computed tomography on diagnostic and treatment strategies in patients with suspected pulmonary embolism

BACKGROUND: Helical computed tomography (CT) has been proposed as a first-line test for the diagnosis of pulmonary embolism. How the test affects the diagnostic evaluation of patients with suspected pulmonary embolism is unknown. METHODS: We examined a cohort of 360 patients evaluated for pulmonary embolism at a teaching hospital in the 4 years following the introduction of the helical CT scan. We collected patient demographic and clinical data to calculate the pretest likelihood of pulmonary embolism; we then read the test results and determined rates of further testing and treatment for pulmonary embolism. RESULTS: After the helical CT scan became available, the number of patients referred for pulmonary embolism testing increased markedly from 170 to 624 total evaluations during 1997 to 2000 (P <0.01). This rise was due to increased use of the helical CT scan (9% to 83% of evaluations, P <0.01) as the use of ventilation-perfusion scanning (79% to 17%, P = 0.03) and pulmonary angiography (12% to <1%, P <0.01) fell. There was no change in the pre-test likelihood of disease over time, but the percentage of scans that were positive for pulmonary embolism rose (14% to 32%, P =0.02). Clinicians treated all patients who had a positive CT scan, but became less likely over time to order further testing for patients who had a negative scan (30% to 12%, P = 0.02). CONCLUSION: At this academic medical center, introduction of the helical CT scan had a profound effect on the evaluation of pulmonary embolism, resulting in more frequent use of the CT scan, and more frequent diagnosis and treatment of pulmonary embolism, despite no change in the pretest probability of disease. Future studies should confirm our findings and determine whether increased detection of pulmonary emboli results in improved outcomes.     

Cost-effectiveness analysis of diagnostic strategies for suspected pulmonary embolism including helical computed tomography

We performed a formal decision analysis to evaluate the cost-effectiveness of various strategies for pulmonary embolism, including helical computed tomography (CT), and determined the most cost-effective schemes for each clinical probability of pulmonary embolism. Other tests included D-dimer (DD), lower limb venous ultrasound (US), ventilation-perfusion (V/Q) scan, and angiography. Outcome measures were 3-month survival and costs per patient managed. Baseline sensitivity of CT was 70%, corresponding to the performance of single-detector CT, and that figure was raised in sensitivity analysis to account for the expected higher sensitivity of newer multidetector CT scanners. All strategies were compared with a reference strategy, namely the V/Q scan in all patients followed when nondiagnostic by an angiogram. For low clinical probability patients, the most cost-effective strategy was DD, US, and V/Q scan, patients with a nondiagnostic V/Q scan being left untreated. Replacing V/Q scan by CT was also cost-effective. For intermediate and high clinical probability patients, a fourth test must be added, either CT or angiography in patients with nondiagnostic V/Q scan, or angiography in patients with a negative helical CT. When using sensitivity figures above 85% (in the multidetector range), DD, US, and CT became the most cost-effective strategy for all clinical probability categories. Helical CT as a single test was not cost-effective. In summary, including helical CT in diagnostic strategies for pulmonary embolism is cost-effective provided that it is combined with DD and US. In contrast, helical CT as a single test is not cost-effective.     

The negative predictive value of spiral computed tomography for the diagnosis of pulmonary embolism in patients with nondiagnostic ventilation-perfusion scans

BACKGROUND: There is no noninvasive method to rule out pulmonary embolism when the clinical suspicion for pulmonary embolism is high. We did a prospective observational study to determine the negative predictive value of spiral computed tomography (CT) in this situation. METHODS: We performed spiral CT scans of the thorax in consecutive patients with high clinical suspicion of pulmonary embolism with intermediate or low probability ventilation-perfusion scans. Patients with negative or indeterminate spiral CT results had conventional angiography at the discretion of the attending physician. Only patients with positive spiral CT results or positive conventional angiograms were treated. All patients were observed for 6 months for evidence of venous thromboembolic disease. Clinical outcome without treatment or the results of conventional angiography were used as reference standards. False-negative results were defined as a negative spiral CT with a positive conventional angiogram or any diagnosis of venous thromboembolism within 6 months. RESULTS: Among the 103 patients who were studied, spiral CT scans were positive in 22 patients, indeterminate in 10 patients, and negative in 71 patients. Twenty-seven (26%) patients had pulmonary embolism by clinical outcome, including 3 of the 71 patients with negative spiral CT scans and 2 of the 10 patients with indeterminate scans. A negative spiral CT result had a likelihood ratio of 0.12 (95% confidence interval [CI]: 0.04 to 0.35) with a negative predictive value of 96% (95% CI: 88% to 99%). Using conventional angiography only as the reference standard, a negative spiral CT result had a likelihood ratio of 0.08 (95% CI: 0.02 to 0.31) and a negative predictive value of 93% (95% CI: 77% to 98%). CONCLUSIONS: Spiral CT has a high negative predictive value for pulmonary embolism and may replace conventional angiography in the workup of pulmonary embolism. Patients with indeterminate spiral CT results should be considered for conventional angiography.     

Electrocardiography and prediction of myocardial damage in patients with acute pulmonary embolism

Acute pulmonary embolism (APE) may lead to myocardial necrosis detected by elevation of cardiac troponin levels. We tried to assess, if electrocardiographic abnormalities may help to define APE patients with myocardial damage and at high risk of complicated clinical course. Therefore we analyzed 50 patients (34F) aged 64.6 +/- 16.9 with confirmed APE. On admission 12-lead standard ECG was recorded and cardiac troponin T (cTnT) was determined quantitatively (Roche). Serum cTnT levels > 0.01 ng/ml, regarded to indicate myocardial injury, were detected in 29 (58%) patients. ST segment depression in ECG was found in 24% of all patients and was more frequent in cTnT + then in group without myocardial injury (41.4% vs 0%, p=0.004). Complicated clinical course and death in acute pulmonary embolism were also more frequently observed in group with ST segment depression (47.1% vs 12.1%, p = 0.03 and 75.0% vs 14.3%, p = 0.02 respectively). Although negative T waves were slightly more frequent in patients with elevated serum troponin T level (65.5% vs 42.9%) and in patients, who died of pulmonary embolism (62.5% vs 54.8%), the difference did not reach statistical significance. Conclusion: ST segment depression detected in standard ECG in patients with APE suggests myocardial injury and may indicate unfavourable clinical course.     

Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators

Purpose

To formulate comprehensive recommendations for the diagnostic approach to patients with suspected pulmonary embolism, based on randomized trials.

Methods

Diagnostic management recommendations were formulated based on results of the Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) and outcome studies.

Results

The PIOPED II investigators recommend stratification of all patients with suspected pulmonary embolism according to an objective clinical probability assessment. D-dimer should be measured by the quantitative rapid enzyme-linked immunosorbent assay (ELISA), and the combination of a negative D-dimer with a low or moderate clinical probability can safely exclude pulmonary embolism in many patients. If pulmonary embolism is not excluded, contrast-enhanced computed tomographic pulmonary angiography (CT angiography) in combination with venous phase imaging (CT venography), is recommended by most PIOPED II investigators, although CT angiography plus clinical assessment is an option. In pregnant women, ventilation/perfusion scans are recommended by many as the first imaging test following D-dimer and perhaps venous ultrasound. In patients with discordant findings of clinical assessment and CT angiograms or CT angiogram/CT venogram, further evaluation may be necessary.

Conclusion

The sequence for diagnostic test in patients with suspected pulmonary embolism depends on the clinical circumstances.     

Appearance of right bundle branch block in electrocardiograms of patients with pulmonary embolism as a marker for obstruction of the main pulmonary trunk.

A number of changes occur in the electrocardiogram (ECG) of pulmonary embolism. This article deals with the diagnostic value of the newly emerged right bundle branch block (RBBB) as a manifestation of acute right ventricular overload. A certain correlation between the extent of obstruction of the pulmonary artery and the appearance of RBBB is established through dynamic monitoring of the ECG. Fifty cases of dissectionally proven pulmonary embolism are observed, in 20 of which massive trunk obstruction had taken place, and in the remaining 30 peripheral embolism in the pulmonary artery was established. With 80% of the trunk embolism patients (16 cases), a newly emerged RBBB was detected in their ECG, and with the remaining 20% (4 cases), ST-segment depression and T-wave inversion in leads V(1)-V(4) were observed as well as right axis deviation. S(1)Q(3)T(3) syndrome was detected among 60% (12 cases) of trunk embolism patients. In none of the peripheral embolism cases was RBBB in the ECG registered. Thus, its appearance on dynamic monitoring of the ECG of pulmonary embolism patients is a significant sign of the probability of massive obstruction of the main pulmonary trunk.     

心电图与超声心动图诊断急性肺栓塞

目的探讨心电图与超声心动图在诊断急性肺栓塞中的应用及临床意义。方法对近年来我院收治的68例经心电图检查高度怀疑急性肺栓塞患者行经胸超声心动图和肺动脉造影检查,并对检查结果进行分析。结果心电图示：典型的SⅠQⅢTⅢ型27例,V1、V2导联T波倒置48例,V1-V3导联T波倒置59例,V1、V2导联ST段抬高〈0.1mV者19例,V1、V2导联ST段抬高0.1-0.2mV者12例,IRBBB45例,肺型P波27例,心房颤动4例,窦速63例。超声心动图示：肺动脉分叉处血栓2例,30例典型右心增大并中度以上肺动脉高压;28例未见明显右心系统形态改变但出现轻度肺动脉高压;典型肺动脉栓塞改变32例。肺动脉造影显示：双侧肺动脉栓塞38例,右肺动脉栓塞11例,右下肺动脉栓塞10例,左侧肺动脉栓塞9例。结论心电图对急性肺栓塞的诊断和判断严重程度及预后虽然作用有限,但紧密结合病情及肺动脉造影和超声心动图检查,可减小肺栓塞心电图误诊几率。     

Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer.

BACKGROUND: The limitations of the current diagnostic standard, ventilation-perfusion lung scanning, complicate the management of patients with suspected pulmonary embolism. We previously demonstrated that determining the pretest probability can assist with management and that the high negative predictive value of certain D -dimer assays may simplify the diagnostic process. OBJECTIVE: To determine the safety of using a simple clinical model combined with D -dimer assay to manage patients presenting to the emergency department with suspected pulmonary embolism. DESIGN: Prospective cohort study. SETTING: Emergency departments at four tertiary care hospitals in Canada. PATIENTS: 930 consecutive patients with suspected pulmonary embolism. INTERVENTIONS: Physicians first used a clinical model to determine patients' pretest probability of pulmonary embolism and then performed a D -dimer test. Patients with low pretest probability and a negative D -dimer result had no further tests and were considered to have a diagnosis of pulmonary embolism excluded. All other patients underwent ventilation-perfusion lung scanning. If the scan was nondiagnostic, bilateral deep venous ultrasonography was done. Whether further testing (by serial ultrasonography or angiography) was done depended on the patients' pretest probability and the lung scanning results. MEASUREMENTS: Patients received a diagnosis of pulmonary embolism if they had a high-probability ventilation-perfusion scan, an abnormal result on ultrasonography or pulmonary angiography, or a venous thromboembolic event during follow-up. Patients for whom the diagnosis was considered excluded were followed up for 3 months for the development of thromboembolic events. RESULTS: The pretest probability of pulmonary embolism was low, moderate, and high in 527, 339, and 64 patients (1.3%, 16.2%, and 37.5% had pulmonary embolism), respectively. Of 849 patients in whom a diagnosis of pulmonary-embolism had initially been excluded, 5 (0.6% [95% CI, 0.2% to 1.4%]) developed pulmonary embolism or deep venous thrombosis during follow-up. However, 4 of these patients had not undergone the proper diagnostic testing protocol. In 7 of the patients who received a diagnosis of pulmonary embolism, the physician had performed more diagnostic tests than were called for by the algorithm. In 759 of the 849 patients in whom pulmonary embolism was not found on initial evaluation, the diagnostic protocol was followed correctly. Only 1 (0.1% [CI, 0.0% to 0.7%]) of these 759 patients developed thromboembolic events during follow-up. Of the 437 patients with a negative D -dimer result and low clinical probability, only 1 developed pulmonary embolism during follow-up; thus, the negative predictive value for the combined strategy of using the clinical model with D -dimer testing in these patients was 99.5% (CI, 99.1% to 100%). CONCLUSION: Managing patients for suspected pulmonary embolism on the basis of pretest probability and D -dimer result is safe and decreases the need for diagnostic imaging.     

Are the American College of Cardiology/American Heart Association guidelines for exercise testing for suspected coronary artery disease correct?

BACKGROUND: Recently published American College of Cardiology (ACC)/American Heart Association (AHA) guidelines state that patients with suspected coronary disease and an intermediate pretest probability are appropriate candidates for exercise ECG, while those with low or high pretest probability are not. METHODS: From 5,103 consecutive patients with symptoms of suspected coronary disease, we evaluated 872 patients who underwent coronary angiography following exercise ECG. Differences in test performance were determined using receiver operating characteristic curve area analysis. A score using age, gender, symptoms, and risk factors was used to classify patients into low, intermediate, and high pretest probability groups. RESULTS: When patients with inadequate exercise tests were excluded, overall sensitivity and specificity were 70% and 66%, respectively. Only the intermediate pretest probability group demonstrated significant incremental value: pretest vs posttest intermediate, 70 +/- 3 vs 79 +/- 3 (p < 0.0001); low, 71 +/- 6 vs 76 +/- 7 (p = 0.39); and high, 69 +/- 8 vs 75 +/- 7 (p = 0.12). From the low- to the high-probability groups, there was a progressive increase in positive predictive value (21%, 62%, and 92%) and decrease in negative predictive value (94%, 72%, and 28%), respectively. The frequencies of abnormal exercise ECGs were lower in the unselected groups compared with the angiography groups (low, 13% vs 36%; intermediate, 22% vs 53%; high, 36% vs 63%). CONCLUSIONS: Based on the information added by exercise testing to clinical data, these results confirm the ACC/AHA guideline assignments for test selection. However, despite these guidelines, patients with a low pretest probability can be selected for exercise testing with the knowledge that a positive result is infrequent and a negative result carries a very high negative predictive value. Intermediate-probability patients on average carry a significant false-negative rate, suggesting that exercise ECG alone may not be a sufficient screening test in all intermediate-probability patients. Because of poor negative predictive value and a large percentage of negative tests, high-probability patients should undergo coronary angiography as the initial strategy, unless the goal of exercise testing is to assess prognosis.     

Prognostic value of the ECG on admission in patients with acute major pulmonary embolism.

A number of ECG abnormalities can be observed in the acute phase of pulmonary embolism (PE). Their prognostic value has not yet been systematically studied in large patient populations. In 508 patients with acute major PE derived from a large prospective registry, the current authors assessed, on admission, the impact of specific pathological ECG findings on early (30-day) mortality. Atrial arrhythmias, complete right bundle branch block, peripheral low voltage, pseudoinfarction pattern (Q waves) in leads III and aVF, and ST segment changes (elevation or depression) over the left precordial leads, were all significantly more frequent in patients with a fatal outcome. Overall, 29% of the patients who exhibited at least one of these abnormalities on admission did not survive to hospital discharge, as opposed to only 11% of the patients without a pathological 12-lead ECG. Multivariate analysis revealed that the presence of at least one of the above ECG findings was, besides haemodynamic instability, syncope and pre-existing chronic pulmonary disease, a significant independent predictor of outcome. In conclusion, ECG may be a useful, simple, non-costly tool for initial risk stratification of patients with acute major pulmonary embolism.     

Strategies incorporating spiral CT for the diagnosis of acute pulmonary embolism: a cost-effectiveness analysis

OBJECTIVE: To assess the cost-effectiveness of spiral CT for the diagnosis of acute pulmonary embolism. DESIGN: Computer-based cost-effectiveness analysis. PATIENTS: Simulated cohort of 1,000 patients with suspected acute pulmonary embolism (PE), with a prevalence of 28.4%, as in the Prospective Investigation of Pulmonary Embolism Diagnosis study. INTERVENTIONS: Using a decision-analysis model, seven diagnostic strategies were compared, which incorporated combinations of ventilation-perfusion (V/Q) scans, duplex ultrasound of the legs, spiral CT, and conventional pulmonary angiography. MEASUREMENTS AND RESULTS: Expected survival and cost (in Canadian dollars) at 3 months were estimated. Four of the strategies yielded poorer survival at higher cost. The three remaining strategies were as follows: (1) V/Q +/- leg ultrasound +/- spiral CT, with an expected survival of 953.4 per 1,000 patients and a cost of $1,391 per patient; (2) V/Q +/- leg ultrasound +/- pulmonary angiography (the "traditional" algorithm), with an expected survival of 953.7 per 1,000 patients and a cost of $1,416 per patient; and (3) spiral CT +/- leg ultrasound, with an expected survival of 958.2 per 1,000 patients and a cost of $1,751 per patient. The traditional algorithm was then excluded by extended dominance. The cost per additional life saved was $70,833 for spiral CT +/- leg ultrasound relative to V/Q +/- leg ultrasound +/- spiral CT. CONCLUSIONS: Spiral CT can replace pulmonary angiography in patients with nondiagnostic V/Q scan and negative leg ultrasound findings. This approach is likely as effective as-and possibly less expensive than-the current algorithm for diagnosis of acute PE. When spiral CT is the initial diagnostic test, followed by leg ultrasound, expected survival improves but costs are also considerably higher. These findings were robust to variations in the assumed sensitivity and specificity of spiral CT.     

Quantitative d-dimer levels and the extent of venous thromboembolism in CT angiography and lower limb ultrasonography

BACKGROUND: We evaluated the diagnostic yield of multidetector-row CT angiography and determined the clot burden within pulmonary vasculature as a measure of pulmonary embolism (PE) severity at different d-dimer levels and pretest clinical probabilities. PATIENTS AND METHODS: 254 consecutive patients referred to CT pulmonary angiography for suspected PE after d-dimer testing were grouped into clinical probability classes using Wells' score, and the frequency of PE was determined. A score representing clot burden within pulmonary vasculature was calculated from the number of obstructed segmental arteries in CT scans in a partly differing group of 96 PE positive patients. RESULTS: The prevalence of PE increases with the d-dimer level (7% at d-dimer levels of 0.5-1 microg/ml, reaching 90% at d-dimer levels > 9 microg/ml; p < 0.001). D-dimer levels above 4 microg/ml are associated with a significantly higher clot burden in pulmonary arteries (median score 11 versus 5, and 53% versus 16% of patients in the subgroup with a score > 10 points; p < 0.001), and thrombus in a main pulmonary artery was detected more frequently (37% versus 9%, p = 0.003). Similar results were obtained for distal versus proximal deep venous thromboses, detected by ultrasonography of the lower limb in a separate group of 44 patients. CONCLUSIONS: High d-dimer levels are associated with an increased prevalence of CT radiographic findings indicating extended clinically severe PE or lower limb venous thrombosis.     

Similarity in Presentation and Response to Thrombolysis Among Women and Men with Pulmonary Embolism

The objective of this study was to compare the therapeutic benefit of thrombolytic therapy in women and men with acute pulmonary embolism. Data were combined from five prospective multicenter trials studying the efficacy and safety of pulmonary embolism thrombolysis. The study was conducted in 34 tertiary care medical centers in the United States, Canada, and Italy. Three hundred and twelve patients (144 women and 168 men) diagnosed with pulmonary embolism by either pulmonary angiography or a combination of high-probability ventilation-perfusion scanning and high clinical suspicion with no contraindications to thrombolytic therapy were included. A thrombolytic agent (either tissue plasminogen activator or urokinase) followed by intravenous heparin was administered. The magnitude of improvement on follow-up ventilation-perfusion scans and pulmonary angiograms and the frequency of important bleeding episodes were measured. The degree of reperfusion with thrombolysis as measured by lung perfusion scanning (mean ± SEM, 11 ± 1% in women vs. 12 ± 1% in men, P = 0.67), improvement in angiographic scores (1.46 ± 0.17 vs. 1.51 ± 0.16, P = 0.85), and decrease in mean pulmonary arterial pressures (1.8 ± 1.0 mmHG vs. 1.3 ± 0.7 mmHG, P = 0.70) demonstrated little difference between the two genders. In addition, the occurrence of important bleeding was similar in women and men (17% vs. 22%, P = 0.23). In conclusion, the benefits and risks posed by thrombolysis for pulmonary embolism are similar in magnitude for women and men. Therefore, patient gender should not influence the decision to treat pulmonary embolism patients with thrombolytic agents.     

Trends in thoracic radiology over a decade at a large academic medical center

OBJECTIVE: To investigate thoracic radiology usage over and above the secular trends associated with hospital-wide changes in the number of patients over a decade. MATERIALS AND METHODS: We retrospectively reviewed administrative data from our 905-bed tertiary-care hospital between January 1, 1992, to December 31, 2001. Three points of entry to the radiology department were identified: inpatient (IP), outpatient (OP), and the emergency room (ER). The total numbers of patients, imaging studies, chest radiographs, chest CTs, CTs for pulmonary embolism, pulmonary angiograms, ventilation/perfusion scintigrams (V/Qs), lung biopsies, cardiac and chest MRIs, and FDG-PET scans for lung nodules and masses were collected. The significance of trends using linear regression analysis was evaluated. RESULTS: IP and OP numbers have significantly increased over a decade (P = 0.04 and P = 0.01 respectively); ER patient numbers have not. There has been an increase in the ratio of chest radiographs per patient arising from the ER area (P = 0.0002). All 3 areas demonstrated an increase in the ratio of chest CTs per patient: IP (P = 0.0002), OP (P = <0.0001), and ER (P = <0.0001). IP and ER areas demonstrated an increase in the ratio of CTs for pulmonary embolism per patient (P = 0.006, P = 0.04 respectively). There was a decrease in the ratios of pulmonary angiograms and V/Qs per IP (P = 0.02 & P = 0.0003 respectively). Cardiac MRIs per patient demonstrated an increase (IP P = 0.01, OP P = 0.02). FDG-PET for lung nodules and masses per patient demonstrated an increase in IP (P = 0.03) and OP (P = 0.003) areas. The total number of chest imaging studies divided by the total number of imaging studies demonstrated an increase in IP and ER areas (P = 0.02 and P = 0.02 respectively). CONCLUSION: There has been an increase in thoracic radiology usage above secular trends, particularly in the regions of chest CT and FDG-PET. CT is replacing more traditional techniques to diagnose pulmonary embolism for inpatients.     

20例犬急性肺栓塞模型的心电图改变及意义

目的分析20例犬急性肺栓塞（PE）模型溶栓前后心电图改变及意义。方法建立20例犬急性PE动物模型后,在急性期及溶栓后行12导联常规心电图检查,分析其心电图表现。结果 20例急性期中,窦性心动过速20例（占100%）;V1导联T波倒置18例（占90%）;V1～V2导联T波倒置17例（占85%）;心房颤动伴心室率〉100次/分13例（占65%）;SⅠ〉0.1mV 11例（占55%）;TⅢ倒置9例（占45%）;QⅢTⅢ8例（占40%）;SⅠQⅢTⅢ5例（占25%）;高度顺钟向转位3例（占15%）;V1～V4导联T波倒置3例（占15%）;电轴右偏（〉＋90°）3例（占15%）;不完全性或完全性右束支阻滞（RBBB）2例（占10%）;V1～V5导联T波倒置2例（占10%）;V1～V6导联T波倒置1例（占5%）;肺型P波1例（占5%）。溶栓后20例中,窦性心动过速或心房颤动伴心室率〉100次/分消失28例（占85%）;胸导联T波倒置加深或由直立变为倒置18例（占90%）;SⅠ变浅或消失10例（占50%）;QⅢTⅢ消失8例（占40%）;TⅢ倒置消失7例（占30%）;SⅠQⅢTⅢ消失5例（占25%）;高度顺钟向转位消失3例（占15%）;不完全性或完全性RBBB消失2例（占10%）;电轴右偏（〉＋90°）消失2例（占10%）;肺型P波消失1例（占5%）。结论急性PE心电图表现是非特异性、非诊断性和有价值的,正确应用有助于急性PE诊断。     

The rehabilitation of clinical assessment for the diagnosis of pulmonary embolism

Pulmonary angiography is the gold standard for diagnosis of segmental pulmonary embolism, but no longer for subsegmental pulmonary embolism because the inter-observer agreement for angiographically documented subsegmental pulmonary embolism is only 60%. A normal rapid ELISA VIDAS D-dimer test result and a normal perfusion scan exclude pulmonary embolism with a negative predictive value of >99%, irrespective of clinical score. The positive predictive value for pulmonary embolism of a high probability VP-scan compared to pulmonary angiography is 87% indicating that 13% of patients with a high probability VP-scan do not have pulmonary embolism. The combination of a negative CUS, a low clinical score, and a non-diagnostic VP-scan safely excludes pulmonary embolism. Patients with a non-diagnostic VP-scan, a negative CUS, but a moderate to high clinical score are candidates for pulmonary angiography. The positive predictive value of helical spiral CT is >95 to 99%. The combination of a negative CUS, a low clinical score, and the presence of a clear alternative diagnosis is predicted to safely exclude pulmonary embolism. Helical spiral CT detects all clinical relevant pulmonary emboli and a large number of alternative diagnoses in symptomatic patients with a non-diagnostic or a high-probability VP-scan. The negative predictive value during 3 months followup after a negative spiral CT for pulmonary embolism in 4 retrospective studies and 1 prospective management study was >99%. Only a small group of patients (1-2%) with a non-diagnostic spiral CT are candidates for pulmonary angiography. Therefore, it is predicted that the spiral CT will replace both VP-scanning and pulmonary angiography to safely exclude or diagnose pulmonary emboli in patients with suspected pulmonary embolism.     

Diagnosing pulmonary embolism in outpatients with clinical assessment, D-dimer measurement, venous ultrasound, and helical computed tomography: a multicenter management study

PURPOSE: To evaluate a diagnostic strategy for pulmonary embolism that combined clinical assessment, plasma D-dimer measurement, lower limb venous ultrasonography, and helical computed tomography (CT). METHODS: A cohort of 965 consecutive patients presenting to the emergency departments of three general and teaching hospitals with clinically suspected pulmonary embolism underwent sequential noninvasive testing. Clinical probability was assessed by a prediction rule combined with implicit judgment. All patients were followed for 3 months. RESULTS: A normal D-dimer level (<500 microg/L by a rapid enzyme-linked immunosorbent assay) ruled out venous thromboembolism in 280 patients (29%), and finding a deep vein thrombosis by ultrasonography established the diagnosis in 92 patients (9.5%). Helical CT was required in only 593 patients (61%) and showed pulmonary embolism in 124 patients (12.8%). Pulmonary embolism was considered ruled out in the 450 patients (46.6%) with a negative ultrasound and CT scan and a low-to-intermediate clinical probability. The 8 patients with a negative ultrasound and CT scan despite a high clinical probability proceeded to pulmonary angiography (positive: 2; negative: 6). Helical CT was inconclusive in 11 patients (pulmonary embolism: 4; no pulmonary embolism: 7). The overall prevalence of pulmonary embolism was 23%. Patients classified as not having pulmonary embolism were not anticoagulated during follow-up and had a 3-month thromboembolic risk of 1.0% (95% confidence interval: 0.5% to 2.1%). CONCLUSION: A noninvasive diagnostic strategy combining clinical assessment, D-dimer measurement, ultrasonography, and helical CT yielded a diagnosis in 99% of outpatients suspected of pulmonary embolism, and appeared to be safe, provided that CT was combined with ultrasonography to rule out the disease.     

Assessment of right ventricular overload in patients with chronic pulmonary disease by 12-lead electrocardiography, vectorcardiography, and body surface electrocardiographic mapping

Twenty-eight patients with chronic pulmonary diseases were examined with standard 12-lead electrocardiogram (ECG), vectorcardiogram (VCG), and body surface ECG mapping (MAP). The electrocardiographic findings were compared with results of 99 mTc radionuclide right ventriculography or T1-201 myocardial scintigraphy. In a stepwise multiple regression analysis between the electrocardiographic parameters and right ventricular ejection fraction, only the amplitude of the negative P wave in V2 (r = 0.69), the posterior force of P loop in VCG (r = 0.71), and the size of -2SD area at 50 msec QRS potential departure map (r = 0.55) were selected as the parameters in standard ECG, VCG, and MAP, respectively. On the radionuclide ventriculography and myocardial scintigraphy, 14 patients were judged to have right ventricular overload. The criteria by VCG, and MAP had better sensitivity and specificity for right ventricle overload than those by 12-lead ECG. VCG criteria of Chou et al had sensitivity of 93% and specificity of 71%. MAP criteria, departure index of F3 or F4 less than or equal to -2, had sensitivity of 86% and specificity of 79%. The electrocardiographic findings by standard 12-lead ECG, VCG and body surface ECG mapping are useful parameters for the noninvasive detection of right ventricular overload in patients with chronic pulmonary diseases.     

Comparison of 3 clinical models for predicting the probability of pulmonary embolism

Two clinical models have been described to predict the probability of pulmonary embolism: the Canadian (or Wells) model, and the Geneva model. A third model has been developed recently at our institution (the Pisa model). We compared the performance of the 3 models in 215 consecutive patients with suspected pulmonary embolism. The clinical probability predicted by the models was categorized as low, intermediate, or high. In all patients, pulmonary angiography was used as the reference diagnostic standard. In patients with pulmonary embolism, the extent of pulmonary embolization was assessed on the lung scan as an index of disease severity.The prevalence of pulmonary embolism was 43.3%, and the median extent of pulmonary embolization at diagnosis was 39.8% (range, 4.5%-75.3%). The proportions of patients categorized as having low, intermediate, or high probability were, respectively: 12%, 60%, and 28%, for the Geneva model; 30%, 55%, and 15%, for the Wells model; 37%, 37%, and 26% for the Pisa model. The frequencies of pulmonary embolism in the low, intermediate, and high probability categories were, respectively: 50%, 39%, and 49% for the Geneva model; 12%, 54%, and 64% for the Wells model; 5%, 42%, and 98% for the Pisa model. Among patients with pulmonary embolism, there was a strong, positive relation between clinical probability predicted by the Pisa model and the extent of pulmonary embolization. The Pisa model proved more accurate than the 2 other models. It may be useful to physicians in defining precisely the pretest probability of pulmonary embolism.     

Novel management strategy for patients with suspected pulmonary embolism.

AIMS: A simple management strategy is required for patients with acute pulmonary embolism which allows a rapid and reliable diagnosis in order to start timely and appropriate treatment. METHODS AND RESULTS: Two hundred and four consecutive patients with suspected pulmonary embolism were managed according to a standardized protocol based on the clinical pretest probability and the initial haemodynamic presentation (shock index=heart rate divided by systolic blood pressure). Patients with a high pretest probability and a positive shock index (> or =1) (n=21) underwent urgent transthoracic echocardiography. Based on the presence or absence of right ventricular dysfunction, reperfusion treatment was initiated immediately. Patients with a negative shock index (<1) (n=183) underwent diagnostic evaluation including pretest probability, D-dimer, and spiral computed tomography (CT) as first-line tests. Echocardiography was performed only when a central pulmonary embolism was found in the spiral CT(n=33). According to our strategy, 98 patients met the diagnostic criteria of pulmonary embolism: 75 patients (all shock index <1) were treated with heparin alone, 16 (seven had a shock index > or =1) with thrombolysis, four (all shock index > or =1) with catheter fragmentation, and three (all shock index > or =1) with surgical embolectomy. The all-cause mortality rate at 30 days was 5%, and at 6 months 11%. Right ventricular dysfunction on baseline echocardiography was not associated with a higher mortality rate at 6 months (logrank 2.4, P=0.12). CONCLUSIONS: The novel management strategy for patients with suspected pulmonary embolism resulted in a rapid diagnosis and treatment with a low 30-day mortality. In patients with pulmonary embolism and a positive shock index, time-consuming imaging tests can be avoided to reduce the risk of sudden death and not to delay reperfusion therapy.