Relationship Between Cardiac Dysfunction and Cerebral Perfusion in Patients with Aneurysmal Subarachnoid Hemorrhage.

INTRODUCTION: Cardiac dysfunction may occur after aneurysmal subarachnoid hemorrhage (aSAH). Although it is associated with poor outcome, the pathophysiological mechanism of this association remains unclear. We investigated the relationship between cardiac function and cerebral perfusion in patients with aSAH. METHODS: We studied 72 aSAH patients admitted within 72 h after ictus with echocardiography and cerebral CT perfusion within 24 h after admission. Cardiac dysfunction was defined as myocardial wall motion abnormalities or positive troponin. In patients with and without cardiac dysfunction, we calculated the mean perfusion [cerebral blood flow (CBF) and time-to-peak (TTP)] in standard regions of interest and calculated differences with 95% confidence intervals (95% CI). RESULTS: In 35 patients with cardiac dysfunction minimal CBF was 15.83 mL/100 g/min compared to 18.59 in 37 without (difference of means -2.76; 95% CI -5.43 to -0.09). Maximal TTP was 26.94 s for patients with and 23.10 s for patients without cardiac dysfunction (difference of means 3.84; 95% CI 1.63-6.05). Mean global CBF was 21.71 mL/100 g/min for patients with cardiac dysfunction and 24.67 mL/100 g/min for patients without cardiac dysfunction (-2.96; 95% CI -6.19 to 0.27). Mean global TTP was 25.27 s for patients with cardiac dysfunction and 21.26 for patients without cardiac dysfunction (4.01; 95% CI 1.95-6.07). CONCLUSION: aSAH patients with cardiac dysfunction have decreased focal and global cerebral perfusion. Further studies should evaluate whether this relation is explained by a direct effect of cardiac dysfunction on cerebral circulation or by an external determinant, such as a hypercatecholaminergic or hypometabolic state, influencing both cardiac function and cerebral perfusion.

CT perfusion during delayed cerebral ischemia after subarachnoid hemorrhage: distinction between reversible ischemia and ischemia progressing to infarction.

INTRODUCTION: Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) can be reversible or progress to cerebral infarction. In patients with a deterioration clinically diagnosed as DCI, we investigated whether CT perfusion (CTP) can distinguish between reversible ischemia and ischemia progressing to cerebral infarction. METHODS: From a prospectively collected series of aSAH patients, we included those with DCI, CTP on the day of clinical deterioration, and follow-up imaging. In qualitative CTP analyses (visual assessment), we calculated positive and negative predictive value (PPV and NPV) with 95% confidence intervals (95%CI) of a perfusion deficit for infarction on follow-up imaging. In quantitative analyses, we compared perfusion values of the least perfused brain tissue between patients with and without infarction by using receiver-operator characteristic curves and calculated a threshold value with PPV and NPV for the perfusion parameter with the highest area under the curve. RESULTS: In qualitative analyses of 33 included patients, 15 of 17 patients (88%) with and 6 of 16 patients (38%) without infarction on follow-up imaging had a perfusion deficit during clinical deterioration (p = 0.002). Presence of a perfusion deficit had a PPV of 71% (95%CI: 48-89%) and NPV of 83% (95%CI: 52-98%) for infarction on follow-up. Quantitative analyses showed that an absolute minimal cerebral blood flow (CBF) threshold of 17.7 mL/100 g/min had a PPV of 63% (95%CI: 41-81%) and a NPV of 78% (95%CI: 40-97%) for infarction. CONCLUSIONS: CTP may differ between patients with DCI who develop infarction and those who do not. For this purpose, qualitative evaluation may perform marginally better than quantitative evaluation.

Different CT perfusion algorithms in the detection of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

INTRODUCTION: Tracer delay-sensitive perfusion algorithms in CT perfusion (CTP) result in an overestimation of the extent of ischemia in thromboembolic stroke. In diagnosing delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH), delayed arrival of contrast due to vasospasm may also overestimate the extent of ischemia. We investigated the diagnostic accuracy of tracer delay-sensitive and tracer delay-insensitive algorithms for detecting DCI. METHODS: From a prospectively collected series of aSAH patients admitted between 2007-2011, we included patients with any clinical deterioration other than rebleeding within 21 days after SAH who underwent NCCT/CTP/CTA imaging. Causes of clinical deterioration were categorized into DCI and no DCI. CTP maps were calculated with tracer delay-sensitive and tracer delay-insensitive algorithms and were visually assessed for the presence of perfusion deficits by two independent observers with different levels of experience. The diagnostic value of both algorithms was calculated for both observers. RESULTS: Seventy-one patients were included. For the experienced observer, the positive predictive values (PPVs) were 0.67 for the delay-sensitive and 0.66 for the delay-insensitive algorithm, and the negative predictive values (NPVs) were 0.73 and 0.74. For the less experienced observer, PPVs were 0.60 for both algorithms, and NPVs were 0.66 for the delay-sensitive and 0.63 for the delay-insensitive algorithm. CONCLUSION: Test characteristics are comparable for tracer delay-sensitive and tracer delay-insensitive algorithms for the visual assessment of CTP in diagnosing DCI. This indicates that both algorithms can be used for this purpose.

CT perfusion on admission and cognitive functioning 3 months after aneurysmal subarachnoid haemorrhage.

Many survivors of aneurysmal subarachnoid haemorrhage (aSAH) have persistent cognitive deficits. Underlying causes of these deficits have not been elucidated. We aimed to investigate if cerebral perfusion in the acute phase after aSAH measured with CT perfusion (CTP) is associated with cognitive outcome 3 months after aSAH. We included 71 patients admitted to the University Medical Center Utrecht who had CTP performed within 24 h after ictus and neuropsychological examination after 3 months. Perfusion values were measured in predefined regions of interest for cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP). The relationship with global cognitive functioning, as measured with a mean z score of all cognitive tests, was examined by linear regression analyses. Adjustments were made for age, education, method of aneurysm treatment, and presence of non-acute medical complications. TTP was associated with cognitive functioning in the univariable analysis (B = -0.042, 95 % CI -0.076 to -0.008), but not after adjustment for age (B = -0.030, 95 % CI -0.065 to 0.004). For CBF, CBV and MTT no relationship with cognitive functioning was observed. Cerebral perfusion measured with CTP within 24 h after onset of aSAH is not associated with cognitive outcome after 3 months. The lack of an association might be explained by the delay between onset of aSAH and CTP. However, CTP assessment within the first minutes after aSAH is impossible in large series of patients.

CT perfusion and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis.

Delayed cerebral ischemia (DCI) is at presentation a diagnosis per exclusionem, and can only be confirmed with follow-up imaging. For treatment of DCI a diagnostic tool is needed. We performed a systematic review to evaluate the value of CT perfusion (CTP) in the prediction and diagnosis of DCI. We searched PubMed, Embase, and Cochrane databases to identify studies on the relationship between CTP and DCI. Eleven studies totaling 570 patients were included. On admission, cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP) did not differ between patients who did and did not develop DCI. In the DCI time-window (4 to 14 days after subarachnoid hemorrhage (SAH)), DCI was associated with a decreased CBF (pooled mean difference -11.9 mL/100 g per minute (95% confidence interval (CI): -15.2 to -8.6)) and an increased MTT (pooled mean difference 1.5 seconds (0.9-2.2)). Cerebral blood volume did not differ and TTP was rarely reported. Perfusion thresholds reported in studies were comparable, although the corresponding test characteristics were moderate and differed between studies. We conclude that CTP can be used in the diagnosis but not in the prediction of DCI. A need exists to standardize the method for measuring perfusion with CTP after SAH, and optimize and validate perfusion thresholds.

Cerebral CT perfusion in patients with perimesencephalic and those with aneurysmal subarachnoid hemorrhage.

BACKGROUND: The cause of perimesencephalic hemorrhage is unknown, but a venous source is suggested. If perimesencephalic hemorrhage is of venous origin, less elevation of the intracranial pressure and less perfusion deficits are expected than after aneurysmal subarachnoid hemorrhage. AIMS: We compared perfusion in the acute stage after perimesencephalic hemorrhage and aneurysmal subarachnoid hemorrhage. METHODS: We included 45 perimesencephalic hemorrhage patients and 45 aneurysmal subarachnoid hemorrhage patients, who were matched on clinical condition at admission and underwent computerized tomographic scanning <72 h after subarachnoid hemorrhage. Cerebral blood flow was assessed in 12 predefined regions of interest. Differences in cerebral blood flow values with corresponding 95% confidence intervals were calculated. Sub-group analyses were performed stratified on comparable amounts of blood and location of blood (posterior circulation aneurysms and additionally in infratentorial and supratentorial aneurysms). RESULTS: Cerebral blood flow was higher in perimesencephalic hemorrhage patients (mean: 63·8) than in aneurysmal sub-arachnoid hemorrhage patients (mean: 55·9; difference of means: -7·9 [95% confidence interval: -10·7 to -5·2]) and also in the sub-group with comparable amounts of blood (mean cerebral blood flow: 56·4; difference of means: -7·4 [95% confidence interval: -10·4 to -4·3]). Cerebral blood flow was comparable with perimesencephalic hemorrhage patients for the sub-group with posterior circulation aneurysms (difference of means: -0·7 [95% confidence interval: -5·2 to 3·8]); however, differences diverged after stratifying posterior circulation aneurysms into supratentorial (difference of means -3·9 [95% confidence interval: -9·3 to 1·4]) and infratentorial aneurysms (difference of means 3·0 [95% confidence interval: -2·8 to 8·8]). CONCLUSIONS: Perimesencephalic hemorrhage patients have a higher cerebral blood flow than aneurysmal subarachnoid hemorrhage patients. The findings of this study further support a venous origin of bleeding in perimesencephalic hemorrhage patients. Future studies should further elaborate on cerebral blood flow in posterior circulation aneurysms.