Cerebrovascular Disease Flashcards
Contraindications to TPA in ischemic stroke
Multiple randomized controlled trials have supported the safety and efficacy of intravenous alteplase (0.9 mg/kg; maximum dose of 90 mg) for confirmed ischemic strokes of less than 3 hours duration.
Contraindications
- Age older than 80 years and a history of diabetes are contraindications for patients with a history of ischemic stroke of 3 to 4.5 hours duration
- Concurrent intravenous abciximab administration
- blood pressure of 185/110 mm Hg or higher
- intracranial hemorrhage on CTA
- a history of stroke, severe head trauma, or intracerebral or intraspinal surgery within 3 months
- gastrointestinal bleeding within 21 days
- concurrent usage of low-molecular weight heparin/thrombin or factor Xa inhibitors
Indications for treating carotid dissection
Indications for surgical or endovascular repair of traumatic carotid dissection
- is fluctuating or deteriorating neurologic symptoms despite optimal medical management
- a contraindication for antithrombotic therapy
- or symptomatic/expanding carotid aneurysm
Carotid Body tumors: % sporadic vs hereditary
Carotid body tumors (CBT) are sporadic in 75% of cases; however, 25% are associated with familial history and/or underlying germline mutations.
When to get genetic testing for carotid body tumors
Genetic testing is recommended in all patients with multi-focal tumors, CBT associated with paraganglioma, CBT associated with pheochromocytoma and or a positive family history.
Carotid Body Tumors are associated with what gene?
The succinate dehydrogenase complex subunit D (SDHD) gene is the most common gene associated with familial paraganglioma. This autosomal dominant, highly penetrant mutation involves the genes encoding 3 subunits of the mitochondrial complex II (succinate dehydrogenase), a component of the Kreb cycle metabolic pathway. These hypoxia-related pathways can be activated by chronic hypoxia (e.g., living at high altitude), leading to increased neural crest call proliferation with decreased apoptosis. Patients with familial CBT tend to be younger (mean age 35 years), have bilateral involvement, and may have associated pheochromocytoma and/or other paraganglioma
Management of acute stent thrmbosis during transfemoral or TCAR procedure
Acute thrombosis of the ICA during carotid stenting is a devastating complication with insufficient data to provide level 1 recommendations. The most recent consensus documents and observational data suggest that the most appropriate first step in this patient who is acutely neurologically decompensated is to attempt to disaggregate the platelet plug and thrombus with administration of intra-arterial abciximab and thrombolytic therapy directly into the ipsilateral carotid artery. Endovascular salvage attempts may ensue, including suction thrombectomy, repeat stenting, and balloon angioplasty. While conversion to CEA may ultimately be required, immediate conversion may also be too time-consuming and physiologically stressful for the patient.
What is cerebral hyperperfusion and how is ot managed?
Cerebral hyperperfusion is an uncommon but potentially life-threatening complication following carotid revascularization, particularly in patients undergoing revascularization (carotid stenting) opposite of severe stenosis or contralateral occlusion.
Characterized by severe hypertension and unilateral migraine-like headache, if left untreated symptoms can progress to seizures and intracerebral hemorrhage, which is associated with mortality rates as high as 75% to 100%. There is no role for heparin in cerebral hyperperfusion syndrome, given the risk of intracerebral hemorrhage. As this clinical scenario is associated with cerebral edema and likely results from dysfunction of the cerebral autoregulation, the primary goal is to strictly control the blood pressure in the postoperative period, using vasodilators such as sodium nitroprusside, nicardipine, nitroglycerin, and others. Most clinicians attempt to maintain the blood pressure to within 20 mm Hg of the preoperative level.
What is the ischemic penumbra?
The ischemic penumbra is the zone of viable, but injured, tissue surrounding an infarct
Segments of the vertebral artery
The vertebral artery is typically divided into 4 segments:
V1 (preforaminal): origin to the transverse foramen of C6;
V2 (foraminal): from the transverse foramen of C6 to the transverse foramen of C2/
V3 (atlantic, extradural or extraspinal): from C2 to the dura/
V4 (intradural or intracranial): from the dura to their confluence to form the basilar artery.
Signs of posterior circulation stroke
Posterior circulation strokes may present with symptoms such as balance disturbances, vertigo, nausea/vomiting, blurred vision or diplopia/oculomotor dysfunction, facial numbness, altered consciousness, or dysarthria. Lymphocele may occur due
Shamblin Classification
The anatomic extent of the carotid body tumor described is consistent with a Shamblin III. The Shamblin classification of carotid body tumors describes the extent of the tumor and correlates with the difficulty of surgical resection and the probability of arterial reconstruction and cranial nerve injury. Class I tumors are localized and are generally resected with a very low probability of carotid artery reconstruction or nerve injury. Class II tumors are adherent to or partially circumscribe the carotid artery. Class III tumors encase the common, external, or internal carotid artery. Resections of large Class II tumors and Class III tumors have a higher probability of necessitating carotid resection and reconstruction and are associated with a higher probability of cranial nerve injury. Preoperative embolization of large Class II and Class III tumors should be considered, but is not mandatory. Proponents of preoperative embolization of carotid body tumors cite a lower blood loss after embolization. The idea that embolization may reduce the risk of cranial nerve injury has not be supported in multiple studies. If preoperative embolization is performed, surgical resection should ensure within 24-36 hours after embolization to minimize the peri-tumor inflammation that ensues after embolization.
What normal flow abnormality can be found in the carotid bulb?
Why?
Flow reversal
Related to diameter and angle of branch vessels
Which vessel has highest diastolic component on doppler? Highest pulsatility during systole and diastole and why?
ICA
ECA, due to reflect waves from branches
What are normal blood flow velocities in the ICA in >60yo? How does it changes in younger patients?
60-90cm/sec
higher likely due to increased CO
How much does blood flow change between mid CCA and CCA near bifurcation? Where should peak CCA systolic velocity be measured?
It increases by 10-20cm/sec
2-4cm below the bulb
What are normal flow velocities in the ECA?
80-115 cm/sec
What are normal peak systolic velocities in the ICA?
usually <100 cm/sec
What things can cause elevated flow velocities? (4)
Stenosis
kinking, coiling
elevated CO
technical error (transducer error)
What features distinguish ICA from ECA? (6)
ICA usually bigger
ICA branches rare
ICA proceeds deep and post towards mastoid (ECA anteriorly)
ICA low resistance
ECA, oscillations with temporal tap
ICA less color variation from diastole to systole (ECA flickers)
What is normal intima-media thickness formula?
(0.009 x age in years) + 0.116
What is usually considered abnormal intima-media thickness?
>0.9mm
What is the international classification for carotid plaque?
type I uniformly sonolucent (>90%)
type 2 predominantly sonolucent (>50%)
type 3 predominantly echogenic (>50%)
type 4 uniformly echogenic
type 5 unclassified (poor visualization)
What method of measuring stenosis did ECST use?
(residual lumen d - original lumen d)/ original lumen d *100%
What method of measuring stenosis did ACAS/NASCET use?
(residual lumen d - lumen d normal distal)/lumen d normal distal * 100%
