Distal embolism during percutaneous revascularization of infra-aortic arterial occlusive disease: an underestimated phenomenon

PURPOSE

To investigate distal embolism during endovascular procedures of the infra-aortic arteries by utilizing a commercial filter basket and unveil any correlation between the baseline clinical and procedural variables and the histopathological findings of the collected particles.

METHODS

In a prospective study, 48 patients (37 men; mean age 70.8+/-7.8 years, range 50- 83) underwent endoluminal therapy of infra-aortic lesions (stenosis >75% or occlusion; mean lesion length 52.2+/-38.0 mm) with standard endovascular procedures. A nitinol filter basket (n=50) was employed for distal protection. The collected particles were histopathologically analyzed. The harvested specimens were quantified after digital image post processing.

RESULTS

Procedural success of filter-protected revascularization was 93.8%. Three failures included 1 vasospasm, 1 distal embolus, and 1 side-branch occlusion. The total area of retrieved particles per basket was 2.76+/-6.49 mm(2) (range 0.0-40.3). Particles with a major axis >1 and >3 mm were detected in 29 (58.0%) and 6 (12.0%), respectively, of the examined filters. Collected particles consisted primarily of platelets and fibrin conglomerates, trapped erythrocytes, inflammatory cells, and extracellular matrix. Increased lesion length, increased reference vessel diameter, acute thromboses, and total occlusions were positively correlated with higher amounts of captured particles (p<0.05). Multivariate analysis incriminated declotting procedures as the only independent predictor of increased embolic burden (p<0.05).

CONCLUSION

The embolism phenomenon during infra-aortic interventions is frequent and underestimated. The liberated particles consisted primarily of atheromatous plaque elements and thrombus. The reported data might support the application of a protective filter basket in selected subsets of lesions with a riskier embolic profile and whenever declotting procedures are performed.

[Long-term survival after a suicidal intravenous injection of mercury]

The authors present extraordinary autopsy findings, i.e. metallic mercury deposits within the cardiac muscle of a 28-year-old deceased of a male sex. Eleven years previously, the man had injected metallic mercury to the vein in the elbow region with a suicidal intent. Eighteen months later, during diagnostic management of dyspnea, metallic deposits in various internal organs had been revealed and a case history of the patient was published. Subsequently, the patient failed to report for follow-up examinations, and finally, committed suicide by hanging.

Tricuspid pouch can cause systemic embolization in adulthood

A 63-year-old-man with significant left hemiplegia was admitted to hospital. He had experienced a transient cerebral ischemic attack 10 years ago. Computed tomography revealed hypodensity along the right lateral ventricle, which corresponded to the left paralysis. Echocardiography and left ventricular angiography revealed an aneurysm of the membranous septum (AMS) without a ventricular septal defect (VSD). Therefore, the embolism was thought to be of cardiac origin, but surgery revealed that it was not caused by AMS. The aneurysm was created when the septal leaflet of tricupid valve formed a giant capsule during the process of natural closure of the VSD. It was a large pouch, 2.0 cm in diameter, adjacent to the septal leaflet. Anomalies of the tricuspid valve, including pouches, can resemble AMS.

Exhaustion of the Frank-Starling mechanism in conscious dogs with heart failure induced by chronic coronary microembolization

The role of the Frank-Starling mechanism in the regulation of cardiac systolic function in the ischemic failing heart was examined in conscious dogs. Left ventricular (LV) dimension, pressure and systolic function were assessed using surgically implanted instrumentations and non-invasive echocardiogram. Heart failure was induced by daily intra-coronary injections of microspheres for 3-4 weeks via implanted coronary catheters. Chronic coronary embolization resulted in a progressive dilation of the left ventricle (12+/-3%), increase in LV end-diastolic pressure (118+/-19%), depression of LV dP/dt(max) (-19+/-4%), fractional shortening (-36+/-7%), and cardiac work (-60+/-9%), and development of heart failure, while the LV contractile response to dobutamine was depressed. A brief inferior vena caval occlusion in dogs with heart failure decreased LV preload to match the levels attained in their control state and caused a further reduction of LV dP/dt(max), fractional shortening, stroke work and cardiac work. Moreover, in response to acute volume loading, the change in the LV end-diastolic dimension-pressure (DeltaLVEDD-DeltaLVEDP) curve in the failing heart became steeper and shifted significantly to the left, while the increases in LV stroke work and cardiac work were blunted. Thus, our results suggest that the Frank-Starling mechanism is exhausted in heart failure and unable to further respond to increasing volume while it plays an important compensatory role in adaptation to LV dysfunction in heart failure.

Distribution of Carotid Arterial Lesions in Chinese Patients With Transient Monocular Blindness

Background and Purpose— Asian patients with cerebrovascular diseases have more intracranial atherosclerosis and less extracranial carotid artery stenosis compared with white patients. We systemically evaluated the distribution of carotid arterial lesions in Chinese patients with transient monocular blindness (TMB), which was rarely reported.

Methods— We prospectively evaluated 105 consecutive patients with TMB. All of the patients received ocular and physical examinations, blood tests for coagulation function and autoimmune diseases, and ultrasonography of cervical and intracranial arteries. All of the carotid lesions were confirmed by magnetic resonance angiography or cerebral angiography.

Results— Of the 36 (34.3%) patients with significant carotid stenosis (≥50%), 16 (15.2%) had extracranial carotid stenosis; 17 (16.2%) had carotid siphon stenosis; and 3 (2.9%) had both. The duration, onset, and patterns of visual loss were not different between patients with and without carotid arterial lesion.

Conclusions— This study signified the importance of carotid siphon stenosis as a probable underlying etiology for TMB in Chinese patients.

Liver ischemia contributes to early islet failure following intraportal transplantation: benefits of liver ischemic-preconditioning

Early graft failure following intraportal islet transplantation (IPIT) represents a major obstacle for successful islet transplantation. Here, we examined the role of islet emboli in the induction of early graft failure and utilized a strategy of ischemic-preconditioning (IP) to prevent early islet destruction in a model of syngeneic IPIT in STZ-induced diabetic mice. Numerous focal areas of liver necrosis associated with the islet emboli were observed within 24 h post-IPIT. Pro-inflammatory cytokines, IL-1beta and IL-6, were significantly increased 3 h after IPIT, while TNF-alpha was elevated for up to 5 days post-IPIT. Caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells were observed in the transplanted islets trapped in areas of necrotic liver at 3 h and 1 day post-IPIT. Hyperglycemia was corrected immediately following IPIT of 200 islets, but recurrence of hyperglycemia was observed within 14 days associated with a poor response to glucose challenge. IP, a procedure of pre-exposure of the liver to transient ischemia and reperfusion, protected the liver from embolism-induced ischemic injury and prevented early islet graft failure. These data suggest that islet embolism in the portal vein is a major cause of functional loss following IPIT that can be prevented by liver IP.

Prolonged Low-Dose Intravenous Thrombolysis in a Stroke Patient With Distal Basilar Thrombus

Background and Purpose— Patients with high-grade basilar artery stenosis secondary to thromboembolism are at high risk of developing subsequent vessel occlusion. Optimal medical management of this condition is unclear.

Summary of Case— We present a patient with a small subacute brain stem infarction and filiform distal basilar residual lumen attributable to arterioarterial or cardiogenic embolism. Beginning 3 days after symptom onset, low-dose intravenous thrombolysis with 0.125 mg/kg recombinant tissue plasminogen activator was continuously infused for 48 hours. Follow-up magnetic resonance angiography revealed complete resolution of the embolus. No further cerebral ischemic episodes occurred during 3-month follow-up, and the basilar artery remained patent.

Conclusion— Our observation suggests a potential for prolonged low-dose intravenous thrombolysis in basilar artery embolism, but further data are needed to judge the effectiveness and risk of this intervention.

Stroke Attributable to a Calcific Embolus From the Brachiocephalic Trunk

Background and Purpose— Calcific brain embolization is a rare event that is usually secondary to cardiac valve calcification. We present a case of stroke caused by embolization of calcific material from the brachiocephalic trunk, probably induced by radiotherapy.

Summary of Case— A 56-year-old right-handed female developed left-sided hemiparesis, hemihypesthesia, and sensory inattention. She had a history of right breast carcinoma that was excised 8 years previously followed by radiotherapy. She had no other history of note. Computed tomography of the head and magnetic resonance imaging confirmed a calcific embolus in right middle cerebral artery and an acute infarction in the corresponding territory. Plain chest radiography, carotid ultrasonography, transthoracic and transoesophageal echocardiography failed to demonstrate the source of calcific embolism. Computed tomography of the thorax revealed heavy calcification of the brachiocephalic trunk and the origin of the right common carotid artery.

Conclusions— Undertaking a vigilant systematic search for the source in cases of calcific embolization is necessary. The aorta and its main branches are possible, yet unusual, sources of calcific emboli that merit investigation.

Mast cell contributes to cardiomyocyte apoptosis after coronary microembolization

Coronary microembolization (CME) is associated with progressive myocardial dysfunction despite restoration of coronary flow reserve (CFR). The potential pathophysiological role of mast cells (MCs) remains unclear. Therefore, we induced CME in 18 miniswines and determined whether MC accumulation occurs and their effects on local cytokine secretion [interleukin (IL)-6, IL-8, tumor necrosis factor-alpha (TNF-alpha)]; cardiomyocyte apoptosis; and collagen formation at day 1 (D1), day 7 (D7), and day 30 (D30) after CME. Four sham-operated animals without CME (controls) and six animals treated with a MC stabilization agent (tranilast) for 30 days after CME were also studied. CFR decreased at D1 but returned to baseline level at D7 and D30. Coronary sinus levels of IL-6, IL-8, and TNF-alpha increased significantly at D1 and D7 (p<0.01 vs baseline). Levels of IL-6 and IL-8 at D30 returned to baseline level, but not those of TNF-alpha. The numbers of total and degranulating MCs, % apoptotic cardiomyocytes, and collagen volume fraction (CVF) over CME myocardium at D1, D7, and D30 were significantly higher than controls (p<0.01). Treatment with tranilast significantly reduced the serum level of TNF-alpha, numbers of total and degranulating MCs, % apoptotic cardiomyocytes, and CVF at D30 (all p<0.05). There was a significant positive correlation between the numbers of MCs with % apoptotic cardiomyocytes (r = 0.77, p<0.001) and CVF (r = 0.75, p<0.001) over the CME myocardium. Despite restoration of CFR, cardiomyocyte apoptosis persisted after CME and was positively correlated with the number of MCs but was prevented with tranilast treatment. These findings suggest that MCs contribute to cardiomyocyte apoptosis after CME.

Heart embolization with the Kirschner wire without cardiac tamponade

The case of the heart embolization with the Kirschner wire that was used for shoulder trauma fixation, 2 years previously in a 67-year-old female, is reported. This case is unique; although embolization of foreign bodies to the heart is not a novel occurrence, heart embolization with non-broken Kirschner wire with a total length of 13.5 cm without cardiac tamponade was not described in medical literature so far.

Suspected fibrocartilaginous embolism in a cat

A 12-year-old cat was presented to the University of Queensland's Small Animal Teaching Hospital with a 1-day history of left hemiparesis of acute onset, with no evidence of trauma or toxin exposure. Neurological examination findings were consistent with a lesion in the caudal left cervical spinal cord (C6 to C8), which was non-painful and had not progressed since the onset of clinical signs. No other abnormalities were found, although myelography showed a mild swelling involving the caudal cervical and cranial thoracic spinal segments. A diagnosis of suspected fibrocartilaginous embolism was made on the basis of the history, clinical presentation and diagnostic tests results, making this case the first report of a suspected fibrocartilaginous embolism in a cat that returned to normal function.

Ultrastructural changes in endothelium during apoptosis indicate low microembolic potential

BACKGROUND

Apoptotic endothelium has been suggested to have microthrombotic and microembolic potential. While some describe pro-coagulant activities and platelet binding, others demonstrate maintained fibrinolytic protein and anti-platelet aggregatory activity. Canalicular fragmentation is unique to apoptotic endothelium and is suggested to facilitate size reduction of apoptotic cells to reduce microembolic potential. Despite the potential importance of apoptotic microemboli, there are no reports characterizing changes in cell size and shape during endothelial apoptosis.

METHODS

Here, we describe transmission and scanning electron microscopic studies of apoptotic endothelium and compare changes seen with apoptotic HL-60 cells incapable of canalicular fragmentation.

RESULTS

We demonstrate reduced endothelial size (p<0.05) with progressive apoptosis relative to apoptotic HL-60 cells. Mechanical stress accelerated size reduction of apoptotic endothelium(P< 0.01) but did not affect the size of apoptotic HL-60 cells. Mechanical stress also increased circularity in apoptotic endothelium (p<0.01), suggested to facilitate passage through small vessels. Earlier work indicated that canaliculi form through plasma membrane invagination, but we report fusion of small vesicles contributing to canalicular growth, while canaliculi fuse to form large vacuoles and also dilate at late stages of apoptosis.

CONCLUSIONS

These observations are consistent with the suggestion that endothelium is adapted to minimize microembolic potential and that canalicular fragmentation contributes to this.

Magnetic resonance imaging findings in spinal cord infarction in three small breed dogs

Fibrocartilaginous embolization (FCE) of the spinal cord is a common disease in large breed dogs. There are only a few reports about this entity in small breed dogs and it has never been reported in chondrodystrophic breed. For definitive diagnosis histopathologic examination is necessary. Magnetic resonance imaging (MRI) as a potential diagnostic tool for intravitam diagnosis of FCE has been mentioned before, but results have not been reported so far. This report describes the neurological findings and MRI results in three small breed dogs, including a Pekingese dog, with FCE of the spinal cord. The disease was suspected in two animals based upon clinical and MRI-appearance and confirmed in the third by histopathological examination. In all three cases, similar focal intramedullary lesions, consisting of hyperintensive signals on T2-weighted images, were detected. Based on these findings, high-field MRI may be used as an antemortem tool for the diagnosis of FCE. It is also shown that FCE can occur in chondrodystrophic dogs.

Diffusion weighted imaging, apparent diffusion coefficient maps and stroke etiology

OBJECTIVE

In acute ischemic stroke, the number and distribution of lesions on diffusion weighted imaging (DWI) have been shown to give clues to the underlying pathogenetic mechanisms. The objective of this study was to determine whether lesion features on DWI differ between stroke due to large artery atherosclerosis (LAA) and cardioembolism (CE), and to assess the role of apparent diffusion coefficient maps (ADC).

METHODS

We retrospectively studied 83 consecutive patients with stroke caused by either LAA (n=40) or cardioembolism (n=43). DWI lesions were characterized by number, size, distribution (i. e. lesion pattern) and signal intensity on ADC maps. In part A, all hyperintense DWI lesions regardless of their ADC were compared. In part B, only hyperintense DWI lesions with hypointense appearance on ADC maps (i. e. acute lesions) were assessed.

RESULTS

Part A: The frequency of multiple hyperintense DWI lesions (LAA: 28/40, CE: 21/43; p< 0.05) and the lesion number (LAA 4.7+/- 4.9; CE: 3.1+/- 4.7; p=0.01) were higher in LAA-patients. Involvement of >1 circulation (i. e. anterior plus posterior or bilateral anterior circulations) was present in 5 LAA-patients (13 %) and 4 CE-patients (9 %). Lesion size did not differ between LAA-stroke (35.1+/- 33.7 mm) and CE-stroke (35.4+/- 27.8 mm). Part B: Multiple hyperintense DWI lesions with low ADC occurred in 23/40 LAA-patients and in 15/43 CE-patients (p<0.05). Lesions in >1 circulation occurred only in CE-stroke (n=3; 7%) and never in LAA-stroke.

CONCLUSIONS

(1) Multiple ischemic lesions occur significantly more often in LAA-stroke than in CE-stroke. (2) ADC maps are important in the comparison of DWI lesion patterns; DWI lesions in >1 circulation can only be assigned to a cardioembolic etiology if they appear hypointense on ADC maps.

Morphometric analysis of particulate debris extracted by four different embolic protection devices from coronary arteries, aortocoronary saphenous vein conduits, and carotid arteries

Different embolic protection devices have been introduced for endovascular interventions: filters or balloon occlusion and aspiration systems. Despite widening use in a variety of vascular beds and clinical syndromes, little is known about the particulate burden liberated from different vascular beds and caught by different protection devices. We performed histologic and morphometric analyses of particulate debris captured during stenting of degenerated saphenous vein bypass grafts and native coronary arteries during acute myocardial infarction or during elective intervention and carotid arteries to assess the relative performance of different protection devices. We analyzed 232 interventions (90 saphenous vein bypass grafts, 77 native coronary arteries, and 65 carotid arteries) with 4 different devices (65 FilterWires, 99 Interceptors, 41 GuardWires, and 27 Proxis catheters) using the RapidVue particle analyzer. No difference in embolic volume retrieved was demonstrated between devices in saphenous vein bypass grafts and carotid interventions. A smaller volume of particulate debris was retrieved by the GuardWire compared with the FilterWire and the Proxis catheter in native coronary artery interventions. The Interceptor and the GuardWire captured more smaller particles than did the FilterWire or Proxis catheter. During saphenous vein bypass graft or carotid intervention, different embolic protection strategies were performed similarly. In native coronary artery stenting, however, proximal embolic protection retrieved larger amounts of debris than did distal filters or occlusion devices. These data may allow greater tailoring of embolic protection device development and application in specific anatomic locales.

The Incidence of Emboli during Cardiac Surgery: A Histopathologic Analysis of 2297 Patients

OBJECTIVE

Manipulation of the atherosclerotic aorta during cardiac surgery is assumed to cause embolization, which can contribute to adverse outcomes. Recently, as a result of worldwide trials deploying the Embol-X intraaortic filter during cardiac surgery, such emboli were captured and processed for histopathologic analysis.

METHODS

Filters with a pore size of 120 microns were placed in 2297 patients who underwent the following operations: coronary artery bypass grafting (CABG) (70%), valve (17%), combination CABG/valve (11%), and other (2%).

RESULTS

The filters captured at least one embolus in 98% of the patients. An average of 8.3 particles was captured per filter (range of 0-74). The surface area of the emboli was on an average 5.8 mm2 (range of 0-188 mm2). Histologic analysis of the captured particles indicated that in 79% of the filters fibrous atheromata were noted, in 44% there were platelets and fibrin, 8% had red blood cell thrombus, 3% had fibro-fatty/adventitial tissue, 2% had other material including cartilage, myocardium, lung, suture, and a teflon pledget. Of the patients enrolled, 1569 were high-risk. The average number of particles captured in the high-risk patients was 8.5 versus 5.8 for the low- to moderate-risk patients (P < .0001). Concomitantly,there was an increase in the embolic burden between the higher- and lower-risk patients (surface area 6.6 vs. 4.0 mm2, P < .0001).

CONCLUSION

These data show the ubiquitous incidence of emboli during cardiac procedures. Intraaortic filtration should reduce adverse outcomes as was demonstrated for the high-risk patients in this study. Aortic manipulation during cardiac surgery can cause embolization and increase morbidity. The use of an intraaortic filter can decrease the embolic burden. We now report the histopathologic analysis of these emboli.

Bone marrow embolism in sickle cell disease: a review

The fat embolism syndrome is an important complication of patients with sickle cell hemoglobinopathies because of severe morbidity and mortality. Our recent experience with three cases that survived with intensive supportive care and prompt use of transfusion stimulates this review. A high index of suspicion, prompt use of diagnostic tools, and aggressive clinical management are the keys to a successful outcome.

Fibrocartilaginous embolization to the spinal cord: serial MR imaging monitoring and pathologic study

We report the serial MR imaging and neuropathologic findings in a patient with fibrocartilaginous embolism to the spinal cord, presumptively originating from vertebral body endplates. Extensive increased T2 signal intensity, minimal contrast enhancing foci, concomitant vertebral body bone marrow infarction, and terminal cord hemorrhagic necrosis were the main MR imaging features. Pathologic examination of the cord demonstrated arteriolar occlusions by chondrocytic thrombi resulting in hemorrhagic necrosis.

Intravasale Raumforderungen der thorakalen Aorta

Aortic intraluminal mass lesions of the thoracic aorta are rare disorders with a wide range of differential diagnoses. Generalized hypercoagulation or vascular endothelial disorders have been proposed as the main etiological factor. The risk of catheter-related thrombus development or embolization after interventional procedures is as high as 17%. Malignancies of the aorta are somewhat rare. In some cases, the specific source of the thrombus could not be determined. Mainly, intraluminal tumors of the thoracic aorta become evident through peripheral embolization. Modern diagnostic tools are able to identify the structure and location of intravascular formations. Therapy options are influenced, due to the heterogenic entity, by the individual risk to the patient and the pathology of the thrombus.

Staphylococcal endocarditis and multiple emboli in a patient with systemic lupus erythematosus

We describe a patient with systemic lupus erythematosus who developed Staphylococcus aureus endocarditis following dental work. Multiple brain and cutaneous septic emboli developed despite aggressive antibiotic therapy.

Relation of nonperfused myocardial volume and surface area to left ventricular performance in coronary microembolization

BACKGROUND

After occlusion of an epicardial artery, left ventricular (LV) dysfunction is closely related to the volume of nonperfused myocardium (NPM). The impact of coronary microembolization (ME) on LV function, however, is larger relative to the total volume of NPM. We hypothesized that the total surface area (SA), rather than the total volume, of NPM is the major determinant of ME-induced LV dysfunction.

METHODS AND RESULTS

We injected microspheres of 10-, 30-, or 100-microm diameter at each of 3 doses selectively into the left anterior descending coronary artery of 48 anesthetized pigs. Electron beam computed tomography (CT) was used to measure regional myocardial perfusion and changes in LV wall thickening (DeltaWT) and stroke volume (DeltaSV) after ME. At postmortem, a transmural "biopsy" of 1 to 2 cm3 of embolized myocardium was imaged by micro-CT, resulting in 3D images that provided volumes and SAs of the individual nonperfused foci. Additionally, in 9 pigs, creatine phosphokinase (CK) activity in embolized myocardium was measured as an index of washout of substances from the NPM. After ME, DeltaWT, DeltaSV, and CK washout were correlated more closely with the total SA (r=0.95, P<0.001; r=0.68, P<0.01; and r=0.88, P=0.01, respectively) than with the total NPM volume (r=0.59, P>0.05; 0.46, P>0.05; and r=0.69, P=0.04, respectively).

CONCLUSIONS

After coronary ME, LV dysfunction is more closely related to the total SA than to the total volume of nonperfused microregions in the myocardium.