Loss of Pulmonary Vascular Volume as a Predictor of Right Ventricular Dysfunction and Mortality in Acute Pulmonary Embolism

International Clinical Practice Guideline Recommendations for Acute Pulmonary Embolism: Harmony, Dissonance, and Silence

Despite abundant clinical innovation and burgeoning scientific investigation, pulmonary embolism (PE) has continued to pose a diagnostic and management challenge worldwide. Aging populations, patients living with a mounting number of chronic medical conditions, particularly cancer, and increasingly prevalent health care disparities herald a growing burden of PE. In the meantime, navigating expanding strategies for immediate and long-term anticoagulation, as well as advanced therapies, including catheter-based interventions for patients with more severe PE, has become progressively daunting. Accordingly, clinicians frequently turn to evidence-based clinical practice guidelines for diagnostic and management recommendations. However, numerous international guidelines, heterogeneity in recommendations, as well as areas of uncertainty or omission may leave the readers and clinicians without a clear management pathway. In this review of international PE guidelines, we highlight key areas of consistency, difference, and lack of recommendations (silence) with an emphasis on critical clinical and research needs.

Effect of Pharmacomechanical Catheter-Directed Thrombolysis on Segmental Artery Occlusions: Insights From the RESCUE Trial

BACKGROUND

Reduction in distal vascular volume in acute pulmonary embolism (PE) is a significant predictor of 30- and 90-day mortality. The likely cause of this is pulmonary arterial obstruction. The effect of pharmacomechanical catheter-directed thrombolysis (PM-CDT) on the occlusions of these pulmonary artery (PA) branches is not known.

OBJECTIVES

The RESCUE study evaluated PM-CDT with the Bashir endovascular catheter in patients with acute intermediate-risk PE. This analysis assessed PA occlusions using core laboratory data before and after PM-CDT therapy.

METHODS

The baseline and 48-hour post-treatment contrast-enhanced chest computed tomography angiography of PE patients with right ventricular dilatation enrolled in the RESCUE trial were used. The primary analysis was the change in the number of segmental and proximal PA branches with total or subtotal (>65%) occlusions after 48 hours compared to baseline using McNemar's test.

RESULTS

A total of 107 patients enrolled across 18 United States sites comprised this analysis. At 48 hours post-PM-CDT, the number of segmental PA branches with total or subtotal occlusions decreased from 40.5% to 11.7% (P < 0.0001). Proximal PA branch total or subtotal occlusions decreased from 28.7% to 11.0% (P < 0.0001). The reduction in segmental artery occlusions correlated significantly with the magnitude of reduction in right ventricular/left ventricular ratio (correlation coefficient of 0.287 [95% CI: 0.102-0.452]; P= 0.0026), whereas that in the proximal PA arteries did not (correlation coefficient of 0.132 [95% CI: 0.059-0.314] P= 0.173).

CONCLUSIONS

PM-CDT with the Bashir catheter was associated with a significant reduction in total and subtotal occlusion of segmental and proximal PAs.

Time-based reperfusion in haemodynamically unstable pulmonary embolism patients: does early reperfusion therapy improve survival?

High-risk pulmonary embolism (PE) is associated with significant morbidity and mortality. Systemic thrombolysis remains the most evidenced-based treatment for haemodynamically unstable PE, but in daily clinical practice, it remains largely underused. In addition, unlike acute myocardial infarction or stroke, a clear time window for reperfusion therapy, including fibrinolysis, for high-risk PE has not been defined either for fibrinolysis or for the more recently incorporated options of catheter-based thrombolysis or thrombectomy. The aim of the present article is to review the current evidence supporting the potential benefit of earlier administration of reperfusion in haemodynamically unstable PE patients and suggest some potential strategies to further explore this issue.

Successful cardiopulmonary resuscitation of cardiac arrest induced by massive pulmonary embolism under general anesthesia: a case report

Background

While pulmonary embolism (PE) is a common occurrence, a large life-threatening PE is not. Herein, we discuss the case of a patient with a life-threatening PE that occurred under general anesthesia.

Case presentation

We present the case of a 59-year-old male patient who was at bed rest for several days due to trauma, which resulted in femoral and rib fractures and a lung contusion. The patient was scheduled for femoral fracture reduction and internal fixation under general anesthesia. After disinfection and surgical towel laying, there was a sudden occurrence of severe PE and cardiac arrest; the patient was successfully resuscitated. Computed tomography pulmonary angiography (CTPA) was performed to confirm the diagnosis, and the patient's condition improved after thrombolytic therapy. Unfortunately, the patient's family eventually discontinued treatment.

Discussion

Massive PE frequently occurs suddenly, may endanger a patient's life at any point in time, and cannot be diagnosed quickly on the basis of clinical manifestations. Although the vital signs fluctuate greatly and there is insufficient time to conduct more tests, some factors such as special disease history, electrocardiography, end-tidal carbon dioxide, and blood gas analysis may help us determine the preliminary diagnosis; however, the final diagnosis is made using CTPA. Current treatment options include thrombectomy, thrombolysis, and early anticoagulation, of which thrombolysis and early anticoagulation are the most feasible.

Conclusion

Massive PE is a life-threatening disease that requires early diagnosis and timely treatment to save patients' lives.

CT imaging determinants of persistent hypoxemia in acute intermediate-risk pulmonary embolism

The factors associated with persistent hypoxemia after pulmonary embolus (PE) are not well understood. Predicting the need for oxygen post discharge at the time of diagnosis using available CT imaging will enable better discharge planning. To examine the relationship between CT derived imaging markers (automated computation of arterial small vessel fraction, pulmonary artery diameter to aortic diameter ratio (PA:A), right to left ventricular diameter ratio (RV:LV) and new oxygen requirement at the time of discharge in patients diagnosed with acute intermediate-risk PE. CT measurements were obtained in a retrospective cohort of patients with acute-intermediate risk PE admitted to Brigham and Women's Hospital between 2009 and 2017. Twenty one patients without a history of lung disease requiring home oxygen and 682 patients without discharge oxygen requirements were identified. There was an increased median PA:A ratio (0.98 vs. 0.92, p = 0.02) and arterial small vessel fraction (0.32 vs. 0.39, p = 0.001) in the oxygen-requiring group], but no difference in the median RV:LV ratio (1.20 vs. 1.20, p = 0.74). Being in the upper quantile for the arterial small vessel fraction was associated with decreased odds of oxygen requirement (OR 0.30 [0.10-0.78], p = 0.02). Loss of arterial small vessel volume as measured by arterial small vessel fraction and an increase in the PA:A ratio at the time of diagnosis were associated with the presence of persistent hypoxemia on discharge in acute intermediate-risk PE.

Pharmacomechanical Catheter-Directed Thrombolysis With the Bashir Endovascular Catheter for Acute Pulmonary Embolism: The RESCUE Study

BACKGROUND

Catheter-directed thrombolysis (CDT) has been associated with rapid recovery of right ventricular (RV) function. The Bashir catheter was developed for enhanced thrombolysis in large vessels such as the pulmonary arteries (PAs) with lower doses of tissue plasminogen activator (tPA).

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of tPA infused using a pharmacomechanical (PM) CDT device called the Bashir endovascular catheter in patients with intermediate-risk acute pulmonary embolism (PE).

METHODS

Patients with symptoms of acute PE with computed tomographic evidence of RV dilatation were enrolled. The Bashir catheter was used to deliver 7 mg tPA into each PA over 5 hours. The primary efficacy endpoint was the core laboratory-assessed change in computed tomographic angiography-derived RV/left ventricular (LV) diameter ratio at 48 hours, and the primary safety endpoint was serious adverse events (SAEs) including major bleeding at 72 hours.

RESULTS

At 18 U.S. sites, 109 patients were enrolled. The median device placement time was 15 minutes. At 48 hours after PM-CDT, the RV/LV diameter ratio decreased by 0.56 (33.3%; P < 0.0001). PA obstruction as measured by the refined modified Miller index was reduced by 35.9% (P < 0.0001). One patient (0.92%) had 2 SAEs: a retroperitoneal bleed (procedure related) and iliac vein thrombosis (device related). Two other procedure-related SAEs were epistaxis and non-access site hematoma with anemia.

CONCLUSIONS

PM-CDT with the Bashir endovascular catheter is associated with a significant reduction in RV/LV diameter ratio and a very low rate of adverse events or major bleeding in patients with intermediate-risk acute PE. The notable finding was a significant reduction in PA obstruction with low-dose tPA. (Recombinant tPA by Endovascular Administration for the Treatment of Submassive PE Using CDT for the Reduction of Thrombus Burden [RESCUE]; NCT04248868).

Novel Approaches to Imaging the Pulmonary Vasculature and Right Heart

There is an increased appreciation for the importance of the right heart and pulmonary circulation in several disease states across the spectrum of pulmonary hypertension and left heart failure. However, assessment of the structure and function of the right heart and pulmonary circulation can be challenging, due to the complex geometry of the right ventricle, comorbid pulmonary airways and parenchymal disease, and the overlap of hemodynamic abnormalities with left heart failure. Several new and evolving imaging modalities interrogate the right heart and pulmonary circulation with greater diagnostic precision. Echocardiographic approaches such as speckle-tracking and 3-dimensional imaging provide detailed assessments of regional systolic and diastolic function and volumetric assessments. Magnetic resonance approaches can provide high-resolution views of cardiac structure/function, tissue characterization, and perfusion through the pulmonary vasculature. Molecular imaging with positron emission tomography allows an assessment of specific pathobiologically relevant targets in the right heart and pulmonary circulation. Machine learning analysis of high-resolution computed tomographic lung scans permits quantitative morphometry of the lung circulation without intravenous contrast. Inhaled magnetic resonance imaging probes, such as hyperpolarized 129Xe magnetic resonance imaging, report on pulmonary gas exchange and pulmonary capillary hemodynamics. These approaches provide important information on right ventricular structure and function along with perfusion through the pulmonary circulation. At this time, the majority of these developing technologies have yet to be clinically validated, with few studies demonstrating the utility of these imaging biomarkers for diagnosis or monitoring disease. These technologies hold promise for earlier diagnosis and noninvasive monitoring of right heart failure and pulmonary hypertension that will aid in preclinical studies, enhance patient selection and provide surrogate end points in clinical trials, and ultimately improve bedside care.