Transesophageal echocardiography in the detection of cardiovascular sources of peripheral vascular embolism

Aortic Thrombus in a Nonaneurysmal Ascending Aorta

BACKGROUND

Ascending aortic thrombus (AAT) in a nonaneurysmal aorta is an extremely rare event and has potentially catastrophic complications, with a life-threatening risk of myocardial infarction and cerebral embolization. This systematic review aims to elucidate the clinical manifestations and to compare the outcomes of anticoagulation therapy versus open aortic surgery for AAT.

METHODS

The MEDLINE/PubMed databases were extensively searched between 1995 and 2019. All relevant publications on AAT in adults were reviewed, and individual patient data were pooled in this meta-analysis. The primary outcome was AAT resolution. The adverse outcome variables were recurrent arterial embolic events, complications related to open aortic surgery, and mortality during the study period. Chi-squared test and logistic regression analysis were used to compare groups and identify any predictors of mortality.

RESULTS

Overall, 107 patients from 101 articles were included, of whom 29 patients who received anticoagulation therapy and 59 who underwent open aortic surgery were included in the outcome analysis. Among 29 patients treated with initial anticoagulation therapy, the persistence of AAT was observed in 11 patients (38%) and recurrent arterial embolization was developed in 6 patients (21%). All 11 patients in the anticoagulation group underwent secondary aortic surgery for the persistence of AAT with uneventful postoperative course. Compared with patients treated with primary aortic surgery, patients treated with initial anticoagulation therapy had higher risk of recurrent embolization (P = 0.002). No significant difference existed in the mortality rates between the groups (P = 0.106). Hemodynamic instability was an independent predictor of mortality (P = 0.008).

CONCLUSIONS

Anticoagulation therapy and open aortic surgery for AAT show similar results; however, open aortic surgery reliably removes AAT and reduces the risk of recurrent embolization compared with anticoagulation therapy. Furthermore, the preoperative hemodynamic status significantly influences the clinical outcome and is a strong predictor of prognosis.

Initial and intermediate-term treatment of the phantom thrombus (primary non-occlusive mural thrombus on normal arteries)

An embolic event originating from thrombus on an otherwise un-diseased or minimally diseased proximal artery (Phantom Thrombus) is a rare but significant clinical challenge. All patients from a single center with an imaging defined luminal thrombus with a focal mural attachment site on an artery were evaluated retrospectively. We excluded all patients with underlying anatomic abnormalities of the vessel at the attachment site. Six patients with a mean age of 62.5 years were identified over a 2.5-year period. All patients had completed treatment for or had a current diagnosis of malignancy and none were on antiplatelets or other anticoagulants. Four thrombi originated in the aorta proximal to the renal arteries and one originated distal. One thrombus was found in the common carotid artery and one was in an arterialized vein graft. Mean follow-up was 22 months. None of the patients underwent removal or exclusion of the embolic source. With systemic anticoagulation, four of the phantom thrombi were resolved on imaging within 8 weeks, one resolved after 72 weeks. One phantom thrombus reoccurred after 6 months on reduced anticoagulant dosing. There was one acute and one death in follow-up (26 months). One patient required a partial foot amputation secondary to tissue necrosis from the initial thromboembolic event. Arterial thrombi forming on otherwise normal vessels are a distinct clinical entity. In patients with a phantom thrombus, a strategy of therapeutic anticoagulation for management of the embolic source seems to be safe and effective over both the short and intermediate-term.

Transesophageal echocardiography and noncardiac surgery

The use of transesophageal echocardiography (TEE) for monitoring during cardiac and noncardiac surgery has increased exponentially over the past few decades. TEE has evolved from a diagnostic tool to a monitoring device and a procedural adjunct. The close proximity of the TEE transducer to the heart generates high-quality images of the intracardiac structures and their spatial orientation. The use of TEE in noncardiac and critical care settings is not well studied, and the evidence of the benefits of its use in these settings is lacking. Despite the widespread availability of TEE equipment in US hospitals, less than 30% of anesthesiologists are formally trained in the use of perioperative TEE. In this review, the safety and indications of TEE are reviewed and detailed analysis of the best available evidence in this regard is presented. Landmark trials evaluating the use of TEE and its therapeutic impact in noncardiac surgical setting are critically reviewed. This article details recommendations to familiarize anesthesiologists with TEE technology to exploit it to its fullest potential to achieve better patient monitoring standards and eventually improve outcome. Training of greater numbers of anesthesiologists in TEE is needed to increase awareness of the indications and contraindications. Until relatively inexpensive TEE equipment is available, the initial cost of equipment acquisition remains a significant prohibitive factor limiting its widespread use.

Mobile Thrombus of the Thoracic Aorta: Management and Treatment Review

Detection of mobile thrombus of the thoracic aorta has become increasingly higher after any embolic event. Although the indication for treatment remains controversial, there is a growing interest about the ethiopathogenesis of this rare entity, and to define proper diagnostic and therapeutic approaches. The purpose of this article was to review the current management strategies and follow-up results of this rare pathology.

Large mobile thrombus in non-atherosclerotic thoracic aorta as the source of peripheral arterial embolism

The presence of thrombi in the atherosclerotic and/or aneurysmatic aorta with peripheral arterial embolism is a common scenario. Thrombus formation in a morphologically normal aorta, however, is a rare event. A 50 years old woman was admitted to the mergency department for pain, coldness, and anesthesia in the the left foot. She had a 25 years history of cigarette smoking, a history of postmenopausal hormone replacement therapy (HRT), hypercholesterolemia and hyperfibrinogenemia. An extensive serologic survey for hypercoagulability, including antiphospholipid antibodies, and vasculitis disorders was negative. Transesophageal echocardiography revealed a large, pedunculated and hypermobile thrombus attached to the aortic wall 5 cm distal of the left subclavian artery. The patient was admitted to the surgery department, where a 15 cm long fresh, parietal thrombus could be removed from the aorta showing no macroscopic wall lesions or any other morphologic abnormalities.

This case report demonstrates the possibility of evolving a large, pedunculated thrombus in a morphologically intact aorta in a postmenopausal woman with thrombogenic conditions such as hyperfibrinogenemia, hypercholesterolemia, smoking and HRT. For these patients, profiling the individual risk and weighing the benefits against the potential risks is warranted before prescribing HRT.

Mobile thrombus of the thoracic aorta: diagnosis and treatment in 9 cases

Detection of mobile thrombus of the thoracic aorta has become increasingly common thanks to routine exploration using transesophageal echography (TEE) after any embolic event. Although the indication for treatment remains controversial, there is a growing interest in understanding this potential source of arterial emboli and in defining proper diagnostic and therapeutic approaches. The purpose of this study was to evaluate the utility of different diagnostic and therapeutic modalities used in our department over the last 6 years. Between 1995 and 2000, mobile thrombus of the thoracic aorta was diagnosed in 9 patients (5 men, 4 women) with a mean age of 49.2 years (range, 28 to 68 years). In all patients, aortic thrombus was suspected after a peripheral (n = 4) or cerebral (n = 5) vascular event. Treatment using intravenous heparin was attempted in all patients and allowed complete dissolution of thrombus in four. In the remaining five patients, repeat TEE demonstrated persistent thrombus and operative treatment was undertaken. In three patients with thrombosis in the aortic arch, thrombectomy was performed with cardiopulmonary bypass, and deep hypothermic circulatory arrest. In two patients presenting thrombosis in the descending thoracic aorta, thrombectomy was performed with an atriofemoral shunt. Thrombectomy was associated with repair of a wall defect in two patients and resection of atheromatous plaque in one patient. Postoperative recovery was uneventful but recurrence was noted in one patient because anticoagulation therapy was stopped too soon. On the basis of our experience and previous reports, we have defined the following therapeutic strategy. All patients are first treated with heparin. In case of failure, thrombectomy may be undertaken in young patients. Because of the highly invasive nature of the procedure, careful work-up including TEE should be performed to rule out any other cause of embolism and to determine that the lesion presents a high potential for embolism. Follow-up must include long-term coumadin therapy and routine surveillance using TEE or magnetic resonance imaging, since long-term outcome is unclear.

Multiple aortic thrombi associated with protein C and S deficiency

We describe a woman with an unusual case of thromboembolism of the mesenteric artery in whom multiple thrombi were subsequently found in the aorta and right heart chambers on transesophageal echocardiography. Further evaluation revealed a deficiency of protein C and S plasma proteins, inhibitors of the clotting system. The patient was treated successfully with systemic anticoagulation. Aortic thrombus is common in the setting of underlying atherosclerosis. However, the association of aortic thrombus with a deficiency of protein C and S is rare. To our knowledge, this is the first reported case of mural thrombus of the thoracic aorta associated with combined protein C and S deficiency. Our report underscores the important role of transesophageal echocardiography in the evaluation of patients with arterial thromboembolism.

Atherosclerosis of the ascending aorta is an independent predictor of long-term neurologic events and mortality

OBJECTIVES

This study was undertaken to determine whether atherosclerosis of the ascending aorta is a predictor of long-term neurologic events and mortality.

BACKGROUND

Atherosclerosis of the thoracic aorta has been recently considered a significant predictor of neurologic events and peripheral embolism, but not of long-term mortality.

METHODS

Long-term follow-up (a total of 5,859 person-years) was conducted of 1,957 consecutive patients > or =50 years old who underwent cardiac surgery. Atherosclerosis of the ascending aorta was assessed intraoperatively (epiaortic ultrasound) and patients were divided into four groups according to severity (normal, mild, moderate or severe). Carotid artery disease was evaluated (carotid ultrasound) in 1,467 (75%) patients. Cox proportional-hazards regression analysis was performed to assess the independent effect of predictors on neurologic events and mortality.

RESULTS

A total of 491 events occurred in 472 patients (neurologic events 92, all-cause mortality 399). Independent predictors of long-term neurologic events were: hypertension (p = 0.009), ascending aorta atherosclerosis (p = 0.011) and diabetes mellitus (p = 0.015). The independent predictors of mortality were advanced age (p < 0.0001), left ventricular dysfunction (p < 0.0001), ascending aorta atherosclerosis (p < 0.0001), hypertension (p = 0.0001) and diabetes mellitus (p = 0.0002). There was >1.5-fold increase in the incidence of both neurologic events and mortality as the severity of atherosclerosis increased from normal-mild to moderate, and a greater than threefold increase in the incidence of both as the severity of atherosclerosis increased from normal-mild to severe.

CONCLUSIONS

Atherosclerosis of the ascending aorta is an independent predictor of long-term neurologic events and mortality. These results provide additional evidence that in addition to being a direct cause of cerebral atheroembolism, an atherosclerotic ascending aorta may be a marker of generalized atherosclerosis and thus of increased morbidity and mortality.

Recurrent embolism caused by floating thrombus in the thoracic aorta

A case of embolic recurrent episodes resulting in acute lower-limb ischemia from an unusual source is reported. This occurred in a patient on steroids for rheumatoid arthritis. Femoropopliteal thromboembolectomy successfully restored arterial flow. Diagnostic evaluation for identifying the source of embolism revealed a large, pedunculated and mobile thrombus arising from a nonaneurysmatic and nonatherosclerotic descending thoracic aorta. The thrombus was identified by transesophageal echocardiography and was successfully removed by aortic thromboendarterectomy. We emphasize the importance of transesophageal echocardiography as a reliable method for the diagnosis of thoracic aorta diseases and for identification of aortic thrombi. An aggressive surgical approach is recommended in the low-risk patient to prevent further embolic episodes.

Usefulness of transesophageal echocardiography in determining the source of emboli in patients with acute limb ischemia

A potential cardiovascular source of embolism was demonstrated by transesophageal echocardiography in 20 of 33 patients (61%) with acute limb ischemia. The percentage was higher in patients with large artery occlusions (9 of 11, 82%) than in those with small artery occlusions (9 of 22, 41%) (p = 0.026).

Diagnosis and management of patients with peripheral macroemboli from thoracic aortic pathology

Transesophageal echocardiography (TEE) has improved the detection of thoracic aortic pathology and further elucidated its role as a source of peripheral arterial emboli. Since 1993 we have used TEE to evaluate the thoracic aorta in patients with peripheral emboli without identifiable cardiac sources. Five patients suffered a total of eight embolic events originating from thoracic aortic mural thrombus (TAMT). The four females and one male ranged in age from 56 to 82 years. Emboli occurred to the upper extremities in four instances, lower extremities in three instances, and the visceral vessels in a single instance. Thromboembolectomy was performed in each case except for a patient who initially underwent aortobifemoral bypass. He was discovered to have TAMT after a subsequent embolic event. All patients were anticoagulated after TAMT was identified but in one case anticoagulants were discontinued after an intraabdominal hemorrhage. All patients are alive without limb loss while one patient has experienced recurrent embolization despite anticoagulation. TEE is a sensitive and useful diagnostic modality in patients with "cryptogenic" arterial embolization. Whether surgical management or anticoagulation for the primary lesion is optimal therapy remains a question. However, anticoagulation appears effective in this small experience.

Intraoperative transesophageal echocardiography and epiaortic ultrasound for assessment of atherosclerosis of the thoracic aorta

OBJECTIVES

This study sought to determine the role of transesophageal echocardiography (TEE) and epiaortic ultrasound in the detection of atherosclerosis of the ascending aorta in patients undergoing cardiac surgery.

BACKGROUND

Atherosclerosis of the ascending aorta is a major risk factor for perioperative stroke and systemic embolism in patients undergoing cardiac surgery.

METHODS

Forty-four patients underwent prospective evaluation of the ascending aorta with two ultrasound techniques-epiaortic ultrasound and biplane TEE-and by palpation. The severity of atherosclerosis was graded on a four-point scale as normal, mild, moderate or severe.

RESULTS

A comparison of results with biplane TEE and those with epiaortic ultrasound yielded a kappa value of 0.12 (95% confidence interval 0 to 0.25), indicating poor correlation between the two. Compared with epiaortic ultrasound, biplane TEE significantly underestimated the severity of ascending aortic atherosclerosis, and this underestimation was more marked in the distal ascending aorta (p < 0.0001). When compared with epiaortic ultrasound and biplane TEE, palpation of the ascending aorta significantly underestimated the presence and severity of atherosclerosis (p < 0.0001 for both).

CONCLUSIONS

Epiaortic ultrasound is more accurate than TEE for identification of atherosclerosis of the ascending aorta, but both ultrasound techniques are superior to palpation. Epiaortic ultrasound and TEE provide complementary information regarding thoracic aortic atherosclerosis. Modification of surgical technique on the basis of results of intraoperative epiaortic ultrasound and TEE in elderly patients undergoing cardiac procedures may prevent atheroembolic complications.