Impact of morphologic characteristics of central pulmonary thromboemboli in massive pulmonary embolism

A triad algorithm for analysing individual ante- and post-mortem findings to improve the quality of intensive care

Autopsy is an important source of data for education and quality control. The aim of this study was comparison of ante- to post-mortem findings to detect weak points of intensive care unit (ICU) care. Patients who died in our 14-bed university medical ICU care and underwent an autopsy examination over 20 months (September 2007 to May 2009) were included. Modified Goldman's criteria were used to categorise discrepancies between diagnoses and post-mortem findings. A triad algorithm was constructed to analyse individual ante- to post-mortem findings. One hundred and seventy post-mortem examinations were conducted (45.6% autopsy rate). Major diagnostic discrepancies were detected in 20 patients (11.8%); four class I (2.4%) and 16 class II (9.4%). Massive pulmonary embolism with cardiac arrest was the most common class I discrepancy (75%). Triad analysis of major class I discrepancies showed that all patients had a history of chronic disease; the majority (75%) had a short ICU length of stay. In 75% adequate tests were used to detect disorders. There were interpretation problems of bedside data in complex emergency clinical conditions, especially with less experienced ICU physicians. Inappropriate or incorrectly interpreted diagnostic procedures were performed in more than half of cases with class II discrepancies (9/16, 56%). Abdominal ultrasonography was misleading in 31% (5/16) cases with class II discrepancies. In conclusion, triad algorithm analysis revealed problematic interpretation of bedside diagnostics in emergency cases by inexperienced physicians in class I major discrepancies detected at autopsy. No correct test and wrong interpretation of abdominal ultrasonography were major causes of class II discrepancies.

Predictors of In-Hospital Mortality in Patients Receiving Thrombolytic Therapy for Pulmonary Embolism

Predictors of in-hospital mortality from massive pulmonary embolism (PE) were retrospectively assessed in 78 patients who received thrombolytic therapy. Mortality from PE was 19% (15 of 78). Mortality from PE was higher in those with shock, 36% (12 of 33) versus no shock, 7% (3 of 45; P = .001), 21% (7 of 34) with right ventricle (RV) hypokinesis, and 20% (13 of 64) with RV enlargement. Mortality was 14% (2 of 14) with normal cardiac troponin I (cTnI), 19% (4 of 21) with intermediate cTnI, and 22% (8 of 36) with high cTnI (comparisons between groups nonsignificant [NS]). Trends with combinations of risk factors showed the highest mortality with shock plus high cTnI plus RV hypokinesis (57%) or shock plus high cTnI plus RV enlargement (54%). In conclusion, among the single risk factors, shock was associated with the highest in-hospital mortality from PE and combinations with high cTnI and RV enlargement were associated with higher mortalities.

Acute ECG ST-segment elevation mimicking myocardial infarction in a patient with pulmonary embolism

Pulmonary embolism is a common cardiovascular emergency, but it is still often misdiagnosed due to its unspecific clinical symptoms. Elevated troponin concentrations are associated with greater morbidity and mortality in patients with pulmonary embolism. Right ventricular ischemia due to increased right ventricular afterload is believed to be underlying mechanism of elevated troponin values in acute pulmonary embolism, but a paradoxical coronary artery embolism through opened intra-artrial communication is another possible explanation as shown in our case report.

Hybrid treatment with angiographic catheter in massive pulmonary embolism: mechanical fragmentation and fibrinolysis

PURPOSE

Massive pulmonary embolism is a severe clinical condition that requires prompt therapeutic intervention. We report our experience with a hybrid treatment involving systematic fragmentation of the embolus with an angiographic catheter associated with fibrinolytic therapy over the following days.

MATERIALS AND METHODS

From 1999-2005 we treated 164 patients with massive pulmonary embolism. We used the same angiographic catheter for mechanical fragmentation and for administration of the fibrinolytic agent (24-72 h). Results were assessed on the basis of changes in mean pulmonary artery pressure.

RESULTS

After fragmentation with the angiographic catheter, we observed four types of haemodynamic behaviour: in 61 patients (41.4%), mean pulmonary artery pressure fell rapidly below 30 mmHg; in 38 patients (23.1%), two passes were required to achieve the same result; in 32 patients (19.5%) three passes were required. In the remaining 26 patients (15.8%), at no time did the mean pulmonary artery pressure fall below 35 mmHg. The only two deaths occurred in this last group.

CONCLUSIONS

Mechanical fragmentation with the angiographic catheter and administration of fibrinolytic agents effectively brought about a rapid improvement in patients' clinical status by moving the embolus towards the periphery.

Relation of Ultrasound Morphologic Characteristics of Central Pulmonary Artery Thromboemboli to Their Ex Vivo Lysibility

BACKGROUND

Ultrasound morphology of massive central pulmonary artery thromboemboli (TE) is an independent predictor of 30-day mortality. The aim of this study was to asses ex vivo lysibility of morphologically different TE.

METHODS

Forty-five central pulmonary artery TE, collected at autopsies, were divided into hypoechoic (group A) and hyperechoic (group B) categories. TE were lysed with alteplase in a perfusing system simulating pulmonary circulation for 1 hour.

RESULTS

The grey scale mean of thrombi in group B was higher compared with group A (64 +/- 7 vs. 38 +/- 7, respectively, P < .01). Spontaneous lysis in group A did not differ compared with group B (2.2% +/- 0.5% vs. 2.1% +/- 0.4%, P = .4). After incubation with alteplase, the weight of TE was reduced more in group A than in group B (16% +/- 2% vs. 11% +/- 2%, P < .001). The grey scale mean negatively correlated with the percentage of TE weight reduction (0.768) (P < .001).

CONCLUSION

Ultrasound morphology of TE from central pulmonary arteries correlates significantly with ex vivo lysibility. Hypoechoic TE are more susceptible to thrombolysis than hyperechoic TE.

Characterization of pulmonary emboli ex vivo by magnetic resonance imaging and ultrasound

INTRODUCTION

Magnetic resonance imaging (MRI) and transesophageal ultrasound (US) are promising methods for detection and characterization of central pulmonary emboli. Both methods employ different physical principles. We tested how US and MRI characterized pulmonary emboli ex vivo.

METHODS

Thirty six ex vivo pulmonary emboli, obtained during routine autopsies of patients who died of massive pulmonary embolism, were subjected to US imaging (linear vascular probe, 5.7-10 MHz) and to high resolution three-dimensional T1-weighted spin-echo MRI. In another 3 pulmonary thromboemboli and 2 tumor emboli, we compared MRI with immunohistochemistry to platelets, red blood cells and renal carcinoma cells. We also studied model clots in vitro (retracted and non-retracted red whole-blood clots, platelet aggregates and compacted and non compacted fibrin-rich plasma clots) with MRI and US.

RESULTS

T1-weighted MR images of pulmonary thromboemboli consistently showed dark regions that corresponded to red cell-rich regions and bright layers that corresponded to platelet aggregates, but bright signal was obtained also from viable carcinoma cells and necrotic regions in tumor emboli. US images provided less structural detail than MRI, but clot retraction or compaction increased image brightness. The correlation between US and MRI characteristics of pulmonary emboli was poor.

CONCLUSIONS

T1-weighted MRI of pulmonary emboli is capable of non-invasive assessment of the red cell-rich and platelet-rich components of pulmonary thromboemboli. US imaging shows increased brightness with clot retraction or compaction. Thus, both methods detect clot characteristics that influence susceptibility to thrombolytic treatment.

Saddle pulmonary embolism diagnosed by CT angiography: frequency, clinical features and outcome

OBJECTIVE

To assess the frequency, clinical presentation and outcome associated with saddle pulmonary embolism (PE) diagnosed by computed tomographic angiography (CTA).

PATIENTS

Retrospective review of 546 consecutive patients diagnosed to have acute PE by CTA from 1 September 2002 to 31 December 2003.

RESULTS

Fourteen of 546 patients (2.6%) had saddle PE; 10 were men (71%). None of these patients had pre-existing cardiopulmonary disease. Most common presenting symptoms included dyspnea (72%) and syncope (43%). Hypotension was documented in 2 patients (14%). The most common risk factor for PE was obesity (64%). CTA revealed saddle PE and additional filling defects in the main pulmonary arteries in all patients. Echocardiography was performed within 48 h of the PE diagnosis in 10 patients and revealed right ventricular dysfunction in 8 (80%). All patients were initially managed in the hospital, median length of stay of 4 days (range, 1-45 days). Standard anticoagulant therapy with heparin and warfarin was administered to all patients. Five patients (36%) received additional therapy; thrombolytic therapy was administered to 1 patient (7%) and 4 patients (29%) received an inferior vena cava filter. None of the patients died during their hospitalization. Four patients (29%) died following their hospitalization after intervals of 1, 5, 6, and 12 months, respectively. Causes of death were known in 3 patients, all of whom died from progressive malignancy.

CONCLUSION

Saddle PE in patients without pre-existing cardiopulmonary disease is associated with a relatively low in-hospital mortality rate and may not necessitate aggressive medical management.

The effect of single-detector CT versus MDCT on clinical outcomes in patients with suspected acute pulmonary embolism and negative results on CT pulmonary angiography

OBJECTIVE

We sought to compare the clinical outcomes of patients in whom pulmonary embolism (PE) has been ruled out with single-detector CT versus MDCT, given the improved visualization of subsegmental clots with the latter and the recent increase in use of CT for evaluation of PE.

SUBJECTS AND METHODS

Two cohorts of patients undergoing CT for suspected PE with either single-detector CT (3-mm collimation and pitch of 1.7) or MDCT (2-mm collimation and pitch of 1) scanners were prospectively observed and compared using predefined criteria for evidence of subsequent thromboembolic disease during the 6 months after the acquisition of their initial scan.

RESULTS

Ninety-eight patients were scanned using a single-detector CT scanner. Of these, none had evidence of subsequent PE or deep venous thrombosis (DVT), and six (6.1%) died of unrelated causes. Of the 100 patients scanned using an MDCT scanner, one (1.0%) had a subsequent nonfatal PE 2 months after the initial scanning, one (1.0%) had DVT 1 month after the initial scanning, and eight (8.0%) died of unrelated causes. No significant difference was found in either the probability of subsequent thromboembolic events (chi(2) = 0.3183, degrees of freedom [df] = 1, p = 1) or frequency of unrelated deaths (chi(2) = 0.2655, df = 1, p = 0.7829) between patients scanned using single-detector CT or MDCT protocols.

CONCLUSION

Our results show that patients with suspected acute PE and negative CT results have acceptable clinical outcomes in the absence of anticoagulation treatment up to 6 months after acquisition of their initial scan. Furthermore, we found that the increased visualization of smaller, more peripheral arteries afforded by multislice technology did not affect clinical outcome.

Clinical Usefulness of Computed Tomography Study Without Contrast Injection in the Evaluation of Acute Pulmonary Embolism

OBJECTIVE

To evaluate the percentage of cases in which emboli can be detected in unenhanced scans and to identify the cases in which they appear hyperattenuating or hypoattenuating in comparison to the circulating blood.

METHOD

An angio-computed tomography (CT) scan was performed before and after contrast injection in 140 consecutive patients after clinical suspicion of pulmonary embolism. A radiologist analyzed the examination results thus obtained. The enhanced scan was analyzed first, and after detecting the thrombus, the unenhanced scan was evaluated.

RESULTS

Fifty-one examinations were positive for a pulmonary embolism; in 21 cases, it was possible to identify the embolus even in the unenhanced scans. In 10 cases, the clots were hyperattenuating in comparison to the circulating blood; in 5 cases, they were hypoattenuating; and in 6 cases, they were mixed hyper-hypoattenuating.

CONCLUSION

In a relatively high percentage of cases, particularly those of central thromboembolism, it is possible to identify and characterize the clots even in unenhanced scans.

Morphologic characteristics of central pulmonary thromboemboli predict haemodynamic response in massive pulmonary embolism

OBJECTIVE

On hospital admission, the morphology of the central pulmonary artery thromboemboli is an independent predictor of 30-day mortality in patients with massive pulmonary embolism (MPE). This may be due to the differential susceptibility of thromboemboli to thrombolysis. The aim of this study was to assess haemodynamic response to treatment in patients with MPE and morphologically different thromboemboli.

DESIGN

Prospective observational study.

SETTING

An 11-bed closed medical ICU at a 860-bed community general hospital.

PATIENTS

Twelve consecutive patients with shock or hypotension due to MPE and central pulmonary thromboemboli detected by transesophageal echocardiography who were treated with thrombolysis between January 2000 through April 2002.

PROCEDURES

Patients were divided into two groups according to the characteristics of detected central pulmonary thromboemboli: group 1, thrombi with one or more long, mobile parts; and group 2, immobile thrombi. Urokinase infusion was terminated when mixed venous oxygen saturation was stabilized above 60% for 15 min.

RESULTS

At 2 h, the total pulmonary vascular resistance index was reduced more in group 1 than group 2 [from 27+/-12 mmHg/(l.min.m(2)) to 14+/-6 mmHg/(l.min.m(2)) (-52%) vs 27+/-8 mmHg/(l.min.m(2)) to 23+/-10 mmHg/(l.min.m(2)) (-15%), respectively, P=0.04]. In group 1 thrombolysis was terminated earlier than group 2 (89+/-40 min vs 210+/-62 min, respectively, P= 0.0024). The cumulative dose of urokinase used in group 1 was lower than group 2 (1.7+/-0.3 M i.u. vs 2.7+/-0.5 M i.u., respectively, P= 0.023).

CONCLUSION

Haemodynamic stabilization is achieved faster in patients with mobile central thromboemboli detected by transesophageal echocardiography during MPE.

Monitoring mixed venous oxygen saturation in patients with obstructive shock after massive pulmonary embolism

BACKGROUND

Patients with massive pulmonary embolism and obstructive shock usually require hemodynamic stabilization and thrombolysis. Little is known about the optimal and proper use of volume infusion and vasoactive drugs, or about the titration of thrombolytic agents in patients with relative contraindication for such treatment. The aim of the study was to find the most rapidly changing hemodynamic variable to monitor and optimize the treatment of patients with obstructive shock following massive pulmonary embolism.

PATIENTS AND METHODS

Ten consecutive patients hospitalized in the medical intensive care unit in the community General Hospital with obstructive shock following massive pulmonary embolism were included in the prospective observational study. Heart rate, systolic arterial pressure, central venous pressure, mean pulmonary-artery pressure, cardiac index, total pulmonary vascular-resistance index, mixed venous oxygen saturation, and urine output were measured on admission and at 1, 2, 3, 4, 8, 12, and 16 hours. Patients were treated with urokinase through the distal port of a pulmonary-artery catheter.

RESULTS

At 1 hour, mixed venous oxygen saturation, systolic arterial pressure and cardiac index were higher than their admission values (31+/-10 vs. 49+/-12%, p<0.0001; 86+/-12 vs. 105+/-17 mmHg, p<0.01; 1.5+/-0.4 vs. 1.9+/-0.7 L/min/m2, p<0.05; respectively), whereas heart rate, central venous pressure, mean pulmonary-artery pressure and urine output remained unchanged. Total pulmonary vascular-resistance index was lower than at admission (29+/-10 vs. 21+/-12 mmHg/L/min/m2, p<0.05). The relative change of mixed venous oxygen saturation at hour 1 was higher than the relative changes of all other studied variables (p<0.05). Serum lactate on admission and at 12 hours correlated to mixed venous oxygen saturation (r=-0.855, p<0.001).

CONCLUSION

In obstructive shock after massive pulmonary embolism, mixed venous oxygen saturation changes more rapidly than other standard hemodynamic variables.

Principle mechanisms underlying venous thromboembolism: epidemiology, risk factors, pathophysiology and pathogenesis

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are distinct but related aspects of the same dynamic disease process known as venous thromboembolism (VTE). An estimated 200,000 new cases occur in the United States every year, including 94,000 with PE, resulting in an incidence of 23 per 100,000 patients per year-cases. Without treatment, pulmonary embolism is associated with a mortality rate of approximately 30%, causing nearly 50,000 deaths per year. Moreover, based on post-mortem studies, two-thirds of the patients with pulmonary emboli remain undiagnosed. Clinically, PE may present as (1) isolated dyspnea, (2) pleuritic pain and/or hemoptysis, and (3) circulatory collapse. However, clinical history and examination can be notoriously misleading in reaching a diagnosis. A number of acquired etiologic risk factors (predispositions) are associated with a tendency to develop VTE. These include increasing age, immobilization, surgery, trauma, hospital or nursing home confinement, malignancy, neurologic disease with extremity paresis, as well as certain types of oral contraception and hormone replacement therapy. In addition, a variety of genetic risk factors, such as factor V Leiden, protein S or C deficiency have also been identified. However, in at least half of the instances, no predisposing factors can be identified (idiopathic PE). In the majority of cases thromboemboli originate in the deep veins of the calf or pelvis. The pathogenic conditions for VTE comprise a triad of factors and include (1) venous stasis, (2) hypercoagulable states, and (3) vascular endothelium injury. Occlusion of pulmonary arteries has variable and transient clinical and pathophysiologic consequences, involving both mechanical and reflex effects of vascular occlusion with a consecutive perfusion defect as well as the release of vasoactive and other inflammatory mediators. The objectives of this article are to present an overview of the etiologic and pathogenic factors promoting VTE as well as the pathophysiologic and inflammatory processes following PE.