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C F Bladin

Publications and source records attributed to C F Bladin.

At least 37 records · Page 2Linked to original sources
PubMed1995

Carotid Stenosis Index. A new method of measuring internal carotid artery stenosis.

BACKGROUND AND PURPOSE: Current methods of measuring carotid stenosis such as those used in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) have limitations caused by difficulties in measuring the normal width of the distal internal carotid artery (ICA) or the carotid bulb. METHODS: We developed a new technique, the Carotid Stenosis Index (CSI), based on the known anatomic relationship between the common carotid artery (CCA) and ICA (1.2 x CCA diameter=proximal ICA diameter). The normal ICA diameter can therefore be calculated from direct measurement of the CCA. Three blinded observers evaluated the angiograms of 57 patients (114 carotid arteries), previously screened with duplex ultrasonography, using the NASCET, ECST, and CSI methods. In a subset of 30 patients undergoing carotid endarterectomy, comparison was also made to computerized carotid plaque planimetry. RESULTS: The NASCET method could only be applied correctly in 89% and the ECST method in 95% of cases because of overlying vessels or inadequate views of the distal ICA or carotid bulb. An additional 9% of NASCET cases had a "negative" stenosis, in which the stenosis is wider than the distal ICA. The CSI method was applicable in 99% of cases. Interobserver comparison using ANOVA revealed significant differences using NASCET (P < .0001) and ECST (P <.001) but not CSI (P = NS). NASCET had a sevenfold variation (P < .01) and ECST a twofold variation (P < .01) in results compared with CSI. The intraobserver reliability was 0.87 for NASCET, 0.86 for ECST, and 0.90 for CSI. However, the 95% confidence intervals for an individual measurement by an observer were +/- 30% for NASCET, +/- 19% for ECST, and +/- 15% for CSI. With linear methods of measurement there were significant differences between NASCET and CSI (P < .0001) and ECST (P < .0001) but not between CSI and ECST. A comparison of area derivations of these methods to carotid plaque planimetry revealed significant differences from NASCET (P <.0001) but not ECST, CSI, or duplex methods. A CSI nomogram was created, allowing measurement of both linear and area percent stenosis. CONCLUSIONS: CSI is the most reliable validated method of measuring carotid stenosis, and it correlates with duplex and carotid pathology.

Carotid Artery, Common↗
PubMed1995

Do-not-resuscitate orders in acute stroke.

Although the general guidelines for do-not-resuscitate (DNR) orders apply to acute stroke patients, few data are available to aid decision-making. With a view to developing specific guidelines for use in patients with acute stroke, we decided to evaluate the clinical factors associated with DNR orders at our university teaching hospital. We prospectively studied 450 consecutive patients with acute hemispheric strokes (237 men and 213 women, mean age 75 +/- 12 years). Thirty-six patients (8%) had intracerebral hemorrhage (ICH) and 414 (92%) had ischemic strokes. Overall inhospital mortality was 26%. DNR status was given to 31% of all patients at some time during their admission (83% of those died). DNR decision-making was closely associated with the severity of the neurologic deficit (Canadian Neurological Scale score < or = 5); the patient's incapacity for informed DNR decision-making; age (> 60 years); and devastating ICH unsuitable for surgery (p < 0.001). Fifty-three percent of DNR orders were given on admission (first 24 hours of the hospital stay), 35% during the first week of the hospital stay, due to brain damage, and 12% at any time between days 8 and 44 due to systemic complications. Once DNR status was given, 53% of patients continued to receive normal nutrition and 60% still received medical or surgical treatment. Although the current practice of DNR orders in patients with acute stroke is generally satisfactory, some criteria (eg, age and operable ICH) need revision.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Validation of volume blood flow measurements using three-dimensional distance-concentration functions derived from digital x-ray angiograms.

RATIONALE AND OBJECTIVES: The authors present phantom validation of a method for computing pulsatile flow waveforms in arterial vessels from high-frame-rate biplane x-ray angiograms. METHODS: The three-dimensional course of a blood vessel is constructed from biplane digital x-ray angiograms. A parametric image of contrast mass versus time and true three-dimensional path length is generated. Adjacent contrast mass-distance profiles are matched to compute instantaneous velocity, which is multiplied by cross-sectional area to yield volume flow. An electromagnetic flowmeter was used to validate flow estimates in a phantom consisting of 150-mm tubes 3, 4, and 6 mm in diameter, orientated 15 degrees, 30 degrees, and 35 degrees to the imaging plane, with flow rates and waveforms expected in vivo. RESULTS: Mean and peak flows were accurate to within 9% and 10%, respectively, for velocities of less than 1 meter/second at a frame rate of 25 frames per second. CONCLUSIONS: A practical method for computing highly pulsatile flow waveforms in vivo in tortuous vessels is presented.

Algorithms↗
PubMed1994

Frequency and pathogenesis of hemodynamic stroke.

BACKGROUND AND PURPOSE: Hemodynamic stroke is a recognized but poorly described entity. The aim of this study was to define the frequency and pathogenic mechanisms of hemodynamic stroke. METHODS: We prospectively studied 300 consecutive patients with acute ischemic stroke for evidence of a hemodynamic mechanism. All patients with a probable or possible thromboembolic source were excluded. RESULTS: Twenty-nine patients (9.6%) had documented or presumed hypotension at stroke onset, with 27 of 29 (93%) having watershed infarction on computed tomography (CT). Most (21/29) patients had a slow (hours to days) progressive onset to stroke. Myocardial infarction, cardiac arrhythmias, and orthostatic changes in blood pressure related to diabetic dysautonomia and antihypertensive therapy were the predominant causes of hypotension. Ten patients had moderate or severe carotid stenosis (frequently bilateral); 9 had carotid occlusion (19/29 [66%]). Patients with normal carotid arteries (10/29 [34%]) had hypotension with a stuttering onset to stroke and watershed infarction on CT. Many patients continued to have progressive neurological deterioration, often with ongoing hemodynamic instability. Three of 7 patients who underwent carotid endarterectomy had further perioperative ischemic events. Five patients had myocardial infarction, and overall 4 died during 18.4 months of follow-up (mortality, 9%/y). CONCLUSIONS: Recognition of the clinical and CT features of hemodynamic stroke allows early identification and management of cardiac and carotid disease and correction of iatrogenic causes of hypotension, which may reduce the risk of further events.

Aged↗
PubMed1994

Intracranial blood flow velocities in acute ischemic stroke.

BACKGROUND AND PURPOSE: Transcranial Doppler sonography (TCD) can evaluate noninvasively the blood flow velocities and patency of the main trunk of the middle cerebral artery (MCA). Using TCD we evaluated MCA patency and patterns of flow through the circle of Willis in patients with acute stroke. METHODS: Patients with symptoms of hemispheric stroke were evaluated with serial TCD tests during admission. The Canadian Neurological Scale was used to assess neurological deficits. In all cases computed tomographic scan, 99mTc hexamethylpropyleneamine oxime single-photon emission computed tomography, and carotid duplex were performed, and in some cases cerebral angiography. RESULTS: Seventy-five consecutive patients with symptoms of acute ischemic stroke (mean time, 8 +/- 4 hours) were studied. Four circle of Willis perfusion patterns were observed: normal, collateral, stenotic, and occlusive. MCA occlusion or stenosis was seen in 70% of initial TCD studies in the stroke group (n = 50) but not in patients with transient ischemic attacks (n = 25). Eighty-six percent of the initial MCA occlusions had recanalized by 2 weeks after onset. Four patients, evaluated within the first 4 hours after onset, illustrated different patterns of MCA flow. TCD findings were compared with cerebral angiography, computed tomography, and single-photon emission computed tomography. CONCLUSIONS: TCD allows early differentiation of patency and natural history of MCA thromboembolic events. This may have important implications in the decision for thrombolytic therapy.

Acute Disease↗
PubMed1994

Cost of acute stroke care in Toronto, Canada.

BACKGROUND AND PURPOSE: Stroke cost consumes a large proportion of the gross domestic product in all developed countries, and while health care costs are rising, the ability to contain them is diminishing. METHODS: We calculated the cost of acute stroke care for all first admissions to a teaching hospital in Toronto, Canada, in 1991 through 1992 for 285 consecutive patients. RESULTS: The average cost per patient was $27,500 Canadian, and strokes in men cost less than in women ($23,000 versus $32,000 Canadian), for a total cost of $8 million Canadian over 2 years. More women died than men (34% versus 17%, P < .02), mainly from systemic complications of stroke, but because women stayed hospitalized longer, they cost more in the long term. The major factor determining cost was social support, and more men than women went home or to rehabilitation units (P < .02). Family support was greater for men (82%) than women (39%, P < .0002). CONCLUSIONS: Significant cost reductions are more likely to be achieved by altering discharge policies and improving social conditions for early return to the home than by reducing laboratory or medical personnel costs.

Cerebrovascular Disorders↗
PubMed1993

Cerebral perfusion index: a new marker for clinical outcome in acute stroke.

Single-photon emission computed tomography (SPECT) and transcranial Doppler (TCD) ultrasound are of good prognostic value in acute stroke, and combined they may be an accurate way to determine a target group of patients with maximum therapeutic response. Seventy consecutive patients were studied (42 with middle cerebral artery strokes, 18 with transient ischemic attacks {TIAs}; 10 were excluded due to failure of insonation). Two SPECT studies were performed at 2.1 +/- 1.2 and 13.8 +/- 3.1 days after onset. Serial TCD studies were done at 10 hours and at the time of the SPECT studies. Neurological deficit was scored on admission and 2 weeks later (using the Canadian Neurological Scale). Cerebral perfusion index (CPI) was derived by multiplying the values for TCD and SPECT patterns. Positive correlation was obtained in all 16 patients in whom cerebral angiography was performed within the first 3 days after onset. The occlusive TCD pattern and absence of perfusion on SPECT were common in the stroke group (19/42 patients) and were never seen in those with TIAs. A normal TCD pattern and normal perfusion on SPECT were more common in the patients with TIAs (9/18 vs 8/42, p = 0.02; 5/10 vs 1/40, p = 0.0003). The occlusive TCD and SPECT patterns were associated with the highest mean infarction volume (147 +/- 87 vs 19 +/- 21, p less than 0.0001) and all nonocclusive TCD and SPECT patterns were associated with the better short-term outcome (43.2 +/- 33.9 vs 92.4 +/- 20.2, p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Clinical features, pathogenesis, and computed tomographic characteristics of internal watershed infarction.

BACKGROUND AND PURPOSE: Infarction in the internal border-zone region has been described radiologically and pathologically. The aim of this study was to define the clinical and pathophysiological correlates of internal watershed infarction. METHODS: Eighteen consecutive stroke patients with evidence of internal watershed infarction on computed tomography (CT) were studied. RESULTS: Two CT patterns were identified: 6 patients had confluent internal watershed infarction (CIWI), and 12 patients had partial internal watershed infarction (PIWI). Syncopal symptoms and/or documented hypotension were prominent in both groups. Patients with CIWI usually presented with stepwise onset of contralateral hemiplegia and recovered poorly; patients with PIWI usually had discrete episodes of brachiofacial sensorimotor deficit and good recovery. Both groups had evidence of cortical involvement as part of their clinical deficit. Severe carotid occlusive disease was seen in 10 patients, and 12 patients had evidence of transiently impaired cardiac output. Carotid disease (P < .001), cardiac disease (P < .01), and diabetes mellitus (P < .01) were more prevalent in patients with internal watershed infarction compared with our stroke population as a whole. CONCLUSIONS: Distinguishing internal watershed infarction from lacunar and other subcortical infarctions is important because the different pathological mechanisms demand different therapeutic strategies.

Acute Disease↗
PubMed1993

Measuring carotid stenosis. Time for a reappraisal.

BACKGROUND AND PURPOSE: Data from recent multicenter carotid endarterectomy trials have questioned the validity and reliability of Doppler ultrasound in the assessment of carotid stenosis. METHODS: We prospectively analyzed 45 patients undergoing carotid angiography to compare the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) methods of measuring carotid stenosis with those of direct visualization ("eyeballing") and duplex ultrasound. Linear NASCET and ECST measurements were also converted into area using the pi r2 function and termed "squared NASCET" (N2) and "squared ECST" (E2). In 15 of 45 patients undergoing carotid endarterectomy, the carotid plaque was removed intact, sectioned, and photographed for computer measurement of cross-sectional area. Comparison of this "gold standard" was then made to each method of measurement. RESULTS: Comparison between duplex and the various angiographic measurement techniques revealed significant differences between NASCET and duplex (P < .0001), ECST and duplex (P < .01), and E2 and duplex (P < .01) but not between N2, eyeballing, and carotid duplex methods. Even the NASCET and ECST methods themselves differed significantly (P < .006). When comparison was made with computerized planimetric measurements of the carotid plaque, there were significant differences for both NASCET (P < .0007) and ECST (P < .007). Correlation was demonstrated only between planimetry and N2, E2, and duplex. CONCLUSIONS: NASCET and ECST angiographic methods of measurement consistently underestimate the "true" anatomic stenosis. As such, they represent only "indexes" of carotid stenosis severity. Duplex provides a more accurate measurement of carotid stenosis.

Carotid Stenosis↗