Internal embolism

Phillips DA, Davis MA, Fisher M. Selective embolization and clot dissolution with tPA in the internal carotid artery circulation of the rabbit. AJNR Am J Neuroradiol. 1988 9 899-902. 

Touho H, Morisako T, Hashimoto Y, Karasawa J. Embolectomy for acute embolic occlusion of the internal carotid artery bifurcation. Surg Neurol 1999 51 313-320. 

Dissection of the internal carotid and vertebral arteries is a common cause of stroke, particularly in young patients. Although many occur due to trauma, it is estimated that over half occur spontaneously. The mechanism of stroke following arterial dissection is either by artery-to-artery embolism, by thrombosis in situ, or by dissection-induced lumenal stenosis with secondary cerebral hypoperfusion and low-flow watershed infarction. Occasionally, dissection may lead to the formation of a pseudoaneurysm as a source of thrombus formation. Vertebrobasilar dissections that extend intracranially have a higher risk of rupture leading to subarachnoid hemorrhage (SAH). ° ... 

Silverstein MD, Heit JA, Mohr DN, et al. (1998) Trends in the incidence of deep vein thrombosis and pulmonary embolism a 25-year population-based study. Arch Intern Med 158 585-593... 

MCA infarcts are mainly caused by cardioembolism, internal carotid artery (ICA) thrombosis, dissection or embolism and rarely (in Caucasians) by intrinsic MCA disease. MCA atherothrombotic territory infarctions related to intrinsic MCA disease often cause concomitant small cortical (territorial or borderzone) and subcortical infarcts (Min et al. 2000). 

Combined ACA-MCA infarcts can result from embolic occlusion of the distal ICA (carotid T). Combined MCA-PCA infarcts maybe due to simultaneous embolism to the two territories, to a fetal (internal carotid) origin of the PCA or to compression of the PCA by a herniating hemisphere at the edge of the tentorial foramen. 

Schwab et al. used mild hypothermia (33-34°C) in 20 patients with acute severe middle cerebral artery (MCA) infarction for 48-72 h and found mild hypothermia to be safe and feasible (38). Schwab subsequently reported a series of 25 patients with severe MCA infarction treated with the same protocol (39). Intracranial pressure (ICP) was monitored for 3-7 d, and was found to decrease with initiation of hypothermia. ICP increased during re warming in several patients, but not to the levels seen prior to induction of hypothermia. Pneumonia was seen in 40% of patients treated with hypothermia in this trial, which is within the expected range of occurrence in patients with prolonged ventilation (40). Shimizu et al. used mild hypothermia (33°C) in five patients with embolic infarctions involving the internal carotid artery and MCA territories. The hypothermia was maintained for 3-7 d (41). It was found to be safe, but the number of patients was too small to report any efficacy. Another acute stroke trial using convection air to induce mild hypothermia without anesthesia was found to be feasible (42). Temperatures in this trial were reduced only to 35.5°C, and shivering... 

Hansson PO, Welin L, Tibblin G, Eriksson H (1997) Deep vein thrombosis and pulmonary embolism in the general population. The Study of Men Bom in 1913 . Arch Intern Med 157 1665-1670... 

Embolism from thrombus within the cavity of an aneurysm is rare and is difficult to prove in cases where there maybe other potential sources of embolization. Intracranial aneurysms more commonly present with rupture and subarachnoid hemorrhage, whereas internal carotid artery aneurysms tend to cause pressure symptoms including a pulsatile and sometimes painful mass in the neck or pharynx, ipsilateral Horner s syndrome or compression of the lower cranial nerves. Extracranial vertebral artery aneurysms may cause pain in the neck and arm, a mass, spinal cord compression and upper limb ischemia (Catala et al. 1993). 

Ischemic strokes account for around 80-85% of all strokes and are caused by arterial vascular occlusions rarely occlusion in the cerebral venous system may result in ischemic and/or hemorrhagic stroke. Arterial occlusions resulting from cerebral embolism are the most common causes of ischemic strokes, and by about one week after stroke as many as 70-90% of occlusions will have spontaneously recanalized. Emboli typically originate from atherosclerotic stenoses in the internal carotid artery or from sources in the heart such as clots in the left atrium or the left ventricle. Hypertension-induced vascular disease of the small perforating intracerebral arteries is a common cause of lacunar strokes. A classification of the major stroke subtypes is shown in Table 31.1. 

Labs Cr 1.2 mg/dL, international normalized ratio (INR) 1.1, activated partial thromboplastin time (aPTT) 35 seconds, hematocrit (Hct) 38%, platelets 247,000/mm. Doppler ultrasound Partial noncompressibility of the left popliteal vein, nonocclusive clot. Ventilation-perfusion scintigraphy High probability for acute pulmonary embolism. Unmatched ventilation perfusion defect is seen in the left lower lobe. 

Heit JA, Sdverstein MD, Mohr DN, Petterson TM, O Fallon WM, Melton LJ. Risk factors for deep vein thrombosis and pulmonary embolism a population-based case-control study. Arch Intern Med 2000 160 809-15. 

The USP specifies that injectable products be 100% inspected to ensure that the product is free from visible foreign particulate matter (< 788>). This is crucial because particulate matter in injectable drug products is considered a clinical hazard. Particulate matter has been implicated in the formation of granulomas in various internal organs in rats, as well as embolisms and phlebitis in humans.4 Pulmonary capillaries (the smallest capillary vessels in the human body) are about 7 (tm in size. This is why determination of particles about 7 Lm and larger is deemed important. 

P2. Perlick, E., and Kolkoff, W., Zur Frage der Gerinnungsfaktoren und der Kreislauf-regulation. Proc. 1st Intern. Conf. Thrombosis and Embolism, Basel, 1964 pp. 58-61. Schwabe, Basel, 1955. 

A significant number of patients with HCM develop atrial fibrillation. Amiodarone is one of the most effective agents available to maintain normal sinus rhythm in these patients. For patients in chronic atrial fibrillation requiring rate control, a -blocker or verapamil may be used." Anticoagulation should be considered because these patients are at a risk for systemic embolization and stroke. If amiodarone is added to a patient already receiving warfarin, the prothrombin time or international normalized ratio (INR) wfll be increased and should be monitored closely. 

Meignan M, Rosso J, Gauthier H, et al. Systematic lung scans reveal a high frequency of silent pulmonary embolism in patients with proximal deep venous thrombosis. Arch Intern Med 2000 160 159-164. 

Streptokinase is contraindicated in patients with nlcerative wounds, active internal bleeding, recent trauma with possible internal injuries, visceral or intracranial malignancy, ulcerative cohtis, diverticulitis, severe hypertension, acute or chronic hepatic or renal insufficiency, uncontrolled hypoco-agnlation, chronic pulmonary disease with cavitation, sub-acnte bacterial endocarditis or rheumatic valvular disease, recent cerebral embolism, thrombosis, or hemorrhage, and diabetic hemorrhagic retinopathy, becanse excessive bleeding may occur. 

---