Routine Shunting During Carotid Endarterectomy in Patients With Acute Watershed Stroke

Aim:

To evaluate the protective role of routine shunting in patients with acute watershed stroke (WS) undergoing carotid endarterectomy (CEA).

Methods:

A total of 138 patients with symptomatic carotid stenosis (SCS) who underwent CEA after acute ischemic stroke from March 2008 to March 2015 were included in this study. Transient ischemic attacks were excluded. These patients were divided into 2 groups according to the topographic pattern of the stroke on magnetic resonance imaging: group 1, territorial strokes (TS) caused by emboli of carotid origin, and group 2, WS caused by a hemodynamic mechanism related to an SCS. Primary end points were 30-day mortality and postoperative neurological morbidity. The insertion of a Pruitt carotid shunt was performed systematically.

Results:

Ninety (65.2%) patients presented a TS of carotid origin and were included in group 1, and 48 (34.8%) of the 138 patients had a WS related to an SCS and were included in group 2. The median time between clinical onset of the cerebral ischemic event and surgery was 9 days (range: 0-89 days). Postoperative mortality was 0%. Seven (5.1%) patients had an aggravation of the neurological status during the postoperative period, of whom 2 presented a complete regression of the symptoms in less than 1 hour (definitive postoperative neurologic morbidity: 3.6%). Postoperative neurologic morbidity rate was significantly higher in the TS group (7 of 90; 7.8%) compared to the WS group (0 of 48; P = .04). No other independent predictive factor of neurologic morbidity after CEA for an SCS was found.

Conclusions:

Our results suggest that routine shunting should be considered in case of acute WS since it may play a protective role. Further studies are eagerly awaited to better define the timing and the best treatment option for both acute WS and TS related to an SCS in order to reduce postoperative neurologic morbidity.

Communication of inwardly projecting neovessels with the lumen contributes to symptomatic intraplaque hemorrhage in carotid artery stenosis

OBJECT

Recent studies have demonstrated that plaque morphology can contribute to identification of patients at high risk of carotid artery atherosclerosis as well as the degree of stenosis in those with carotid atherosclerosis. Neovascularization of carotid plaques is associated with plaque vulnerability. However, the mechanism of neovascularization in intraplaque hemorrhage (IPH) and its clinical contribution remain undetermined. In this study, the authors aimed to clarify the characteristics of neovessel appearance with a focus on inwardly projecting neovessels, which are reportedly important in plaque advancement.

METHODS

Consecutive patients with moderate to severe carotid atherosclerosis who underwent carotid endarterectomy were prospectively analyzed from 2010 to 2014. The neovessel appearance was categorized into 3 groups based on intraoperative indocyanine green (ICG) videoangiography: early appearance of neovessels from the endothelium (NVe), late appearance of neovessels from the vasa vasorum (NVv), and no appearance of vessels. Each neovessel pattern was evaluated with respect to clinical, radiological, and pathological findings including IPH, neovascularization, hemosiderin spots, and inflammation.

RESULTS

Of 57 patients, 13 exhibited NVe, 33 exhibited NVv, and 11 exhibited no neovessels. Overall, the interobserver and intraobserver reproducibilities of neovessel appearance were substantial for ICG videoangiography (κ=0.76) and at 7 days postoperatively (κ=0.76). There were no significant differences in baseline characteristics among the 3 groups, with the exception of a higher percentage of symptomatic presentations in patients with NVe (artery-to-artery embolic infarction in 61.5% and transient ischemic attack in 23.1%). Moreover, patients with NVe exhibited larger infarctions than did those with NVv (9675.0±5601.9 mm3 vs 2306.6±856.9 mm3, respectively; p=0.04). Pathologically, patients with NVe had more severe IPH (47.2±8.3 mm2 vs 19.8±5.2 mm2, respectively; p<0.01), hemosiderin spots (0.5±0.2 mm2 vs 0.2±0.1 mm2, respectively; p=0.04), neovessels (0.4±0.7 mm2 vs 0.1±0.4 mm2, respectively; p=0.11), and inflammation (1.0±1.1 mm2 vs 0.6±0.9 mm2, respectively; p=0.26) around the endothelium than did patients with NVv, and all of these parameters were correlated with hyperintensity on time-of-flight MRI. However, the neovessel and inflammation differences were nonsignificant. Interestingly, inflammation was significantly correlated with neovessel formation (r=0.43, p=0.0008), hemosiderin spots (r=0.62, p<0.0001), and IPH (r=0.349, p=0.0097), suggesting that inflammation may be a key factor in plaque vulnerability.

CONCLUSIONS

Communication of inwardly projecting neovessels with the lumen and inflammation synergistically contribute to IPH and symptomatic presentations in patients with carotid stenosis and are more specific than the vasa vasorum. This condition could be a new therapeutic target, and regression of luminal neovessel sprouting and inflammation may help to prevent IPH development and a symptomatic presentation.

Middle cerebral artery pulsatility index and cognitive improvement after carotid endarterectomy for symptomatic stenosis

OBJECT

Transcranial Doppler (TCD) is frequently used to evaluate peripheral cerebral resistance and cerebral blood flow (CBF) in the middle cerebral artery prior to and during carotid endarterectomy (CEA). Patients with symptomatic carotid artery stenosis may have reduced peripheral cerebral resistance to compensate for inadequate CBF. The authors aim to determine whether symptomatic patients with reduced peripheral cerebral resistance prior to CEA demonstrate increased CBF and cognitive improvement as early as 1 day after CEA.

METHODS

Fifty-three patients with symptomatic CEA were included in this observational study. All patients underwent neuropsychometric evaluation 24 hours or less preoperatively and 1 day postoperatively. The MCA was evaluated using TCD for CBF mean velocity (MV) and pulsatility index (PI). Pulsatility index ≤ 0.80 was used as a cutoff for reduced peripheral cerebral resistance.

RESULTS

Significantly more patients with baseline PI ≤ 0.80 exhibited cognitive improvement 1 day after CEA than those with PI > 0.80 (35.0% vs 6.1%, p = 0.007). Patients with cognitive improvement had a significantly greater increase in CBF MV than patients without cognitive improvement (13.4 ± 17.1 cm/sec vs 4.3 ± 9.9 cm/sec, p = 0.03). In multivariate regression model, a baseline PI ≤ 0.80 was significantly associated with increased odds of cognitive improvement (OR 7.32 [1.40-59.49], p = 0.02).

CONCLUSIONS

Symptomatic CEA patients with reduced peripheral cerebral resistance, measured as PI ≤ 0.80, are likely to have increased CBF and improved cognitive performance as early as 1 day after CEA for symptomatic carotid artery stenosis. Revascularization in this cohort may afford benefits beyond prevention of future stroke. Clinical trial registration no: NCT00597883 ( ClinicalTrials.gov ).

Microembolism Versus Hemodynamic Impairment in Rosary-Like Deep Watershed Infarcts

Background and Purpose—

Deep watershed infarcts are frequent in high-grade carotid disease and are thought to result from hemodynamic impairment, particularly when adopting a rosary-like pattern. However, a role for microembolism has also been suggested, though never directly tested. Here, we studied the relationships among microembolic signals (MES) on transcranial Doppler, rosary-like deep watershed infarcts on brain imaging, and cerebral hemodynamic compromise on positron emission tomography (PET), all in severe symptomatic carotid disease. We hypothesized that rosary-like infarcts would be significantly associated with worse hemodynamic status, independent of the presence of MES.

Methods—

Sixteen patients with ≥70% carotid disease ipsilateral to recent transient ischemic attack/minor stroke underwent magnetic resonance imaging including diffusion-weighted imaging, 15 O-PET, and transcranial Doppler. Mean transit time, a specific marker for hemodynamic impairment, was obtained in the symptomatic and unaffected hemispheres.

Results—

Eleven of 16 patients had rosary-like infarcts (Rosary+) and 8 patients had MES. Mean transit time was significantly higher ( P =0.008) in Rosary+ patients than in healthy controls ( n =10), and prevalence of MES was not different between Rosary+ and Rosary− patients. Contrary to our hypothesis, however, the presence of MES within the Rosary+ subset was associated ( P =0.03) with a better hemodynamic status than in their absence, with a significant ( P =0.02) negative correlation between mean transit time and rate of MES/h.

Conclusions—

Contrary to mainstream understanding, rosary-like infarcts were not independent of presence and rate of MES, suggesting that microembolism plays a role in their pathogenesis, probably in association with hemodynamic impairment. Pending confirmation in a larger sample, these findings have management implications for patients with carotid disease and rosary-like infarcts.

Watershed Infarcts in Transient Ischemic Attack/Minor Stroke With ≥50% Carotid Stenosis

Background and Purpose— Watershed ischemia is a significant cause of stroke in severe carotid disease, but its pathophysiology is unsettled. Although hemodynamic compromise has long been regarded as the main mechanism—particularly with deep watershed infarction—there is some contradictory evidence from clinical and pathological studies for a role of microembolism, thought to result from plaque inflammation. However, no study so far has directly addressed these conflicting scenarios.

Methods— In 16 consecutive patients with recent transient ischemic attack/minor stroke and ipsilateral 50% to 99% carotid stenosis, we prospectively obtained (1) plaque inflammation mapping with 18 F fluorodeoxyglucose positron emission tomography; (2) brain MRI and perfusion MR; and (3) transcranial Doppler detection of microembolic signals (MES). Patients were excluded if on dual antiplatelets or with a potential cardiac source of emboli or contralateral MES.

Results— We found the expected significant relationship between (1) degree of stenosis and severity of distal hemodynamic impairment in the watershed areas; and (2) degree of in vivo plaque inflammation and rate of MES/hr. Deep watershed infarcts were present in 8 patients and MES in 8 (3 with both). There was no systematic association between the presence of deep watershed infarcts and either hemodynamic impairment or MES, but deep watershed infarcts were present only when either hemodynamic impairment or MES was present ( P =0.01).

Conclusion— This pilot study supports the idea that in symptomatic carotid disease, deep watershed infarcts result either from hemodynamic impairment secondary to severe lumen stenosis or from microembolism secondary to plaque inflammation. There was no direct evidence that both mechanisms act in synergy.

Hydrogen sulfide: regulatory role on blood pressure in hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) is a metabolic disorder marked by an excess amount of the amino acid homocysteine (Hcy) in the blood stream. Hcy is a H(2)S precursor-formed from the metabolism of methionine. Elevated Hcy levels have been associated with higher blood pressure. However, the precise contribution of H(2)S to blood pressure in HHcy is not known. In the current study, we have examined a novel link between H(2)S, blood pressure and HHcy. Male Sprague-Dawley rats were injected with PAG, NaHS, L-NAME+PAG and saline. HHcy condition was induced by providing methionine (1 g/kg) in drinking water for 8 weeks. After 8 weeks, plasma Hcy and H(2)S were measured. The treated rats were anaesthetized with a mixture of ketamine hydrochloride and medetomidine. Blood pressures were measured by intra-carotid artery catheterization and to further investigate the immediate effect of NO and H(2)S, exogenous drugs namely NaHS, SNP, Ach and NA were administered. Plasma Hcy levels were higher in HHcy groups and this group exhibited hypertension. We observed high blood pressure at low levels of H(2)S and vice versa. Endogenous H(2)S in HHcy condition facilitated a mild decrease in MAP (Mean Arterial Pressure). Exogenous SNP (NO donor) showed a greater pressure decrease in HHcy group. The underlying mechanism is yet to be exploited. High levels of Hcy play an important role in the pathogenesis of hypertension. The results suggest that both endogenous and exogenous H(2)S may play a vital role in regulating blood pressure in HHcy.