Identification of Hemodynamic Compromise by Cerebrovascular Reserve and Oxygen Extraction Fraction in Occlusive Vascular Disease

Nemoto, Edwin M.; Yonas, Howard; Kuwabara, Hiroto; Pindzola, Ronda R.; Sashin, Donald; Meltzer, Carolyn C.; Price, Julie C.; Chang, Yue‐Fang; Johnson, David W.

doi:10.1097/01.wcb.0000125887.48838.37

Cited by 68 publications

(60 citation statements)

References 37 publications

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“…In previous studies involving experimental stroke in baboons and humans (39,40), most of the tissue with the highest oxygen extraction fraction, the lowest rCBF, and an impaired cerebrovascular reserve went into a lacunartype of infarction earlier than tissue that was less severely affected. Furthermore, major reperfusion and lesser infarct growth predicted better neurological outcome after stroke (41).…”

Section: Discussionmentioning

confidence: 90%

Significance of the perfusion‐diffusion mismatch in chronic cerebral ischemia

Surikova

Meisel

Siebler

et al. 2006

Magnetic Resonance Imaging

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Purpose: To determine whether the perfusion deficit could predict brain infarction in patients with chronic cerebral ischemia who experienced recurring episodes of neurological symptoms and showed a perfusion-diffusion mismatch on magnetic resonance (MR) images. Materials and Methods:In 53 consecutive patients (38 males and 15 females, 62 Ϯ 13 years old) with ischemia in the middle cerebral artery (MCA) territory, lesion volumetry was performed on parametric maps of the time-to-peak, the cerebral blood volume, and diffusion-weighted (DW) images. The infarct lesions were assessed on follow-up T2-weighted (T2W) MR images after eight days. Cerebrovascular changes were determined by time-of-flight (TOF) MR angiography (MRA). Inferential and correlation statistics were used. Results:Patients with chronic ischemic brain disease (N ϭ 39) who presented with a severe perfusion-diffusion mismatch in the presence of a normal cerebral blood volume had no or small brain infarctions as found on follow-up T2W images. MRA revealed widespread abnormalities of the basal cerebral arteries compatible with brain perfusion abnormalities. In contrast, in acute stroke patients (N ϭ 14) the deficit of cerebral perfusion predicted the infarct lesion in the T2W images. Conclusion:Our results suggest that in chronic cerebral ischemia the normal blood volume was maintained despite the depression of cerebral perfusion and recurring minor insults.

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Section: Discussionmentioning

confidence: 90%

Significance of the perfusion‐diffusion mismatch in chronic cerebral ischemia

Surikova

Meisel

Siebler

et al. 2006

Magnetic Resonance Imaging

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“…On the other hand, recent studies analyzing a larger number of patients have proved that the decrease in CVR and increased OEF did not necessarily parallel each other (8,9). Nemoto et al (9) reported that about 40% of patients with reduced CVR had normal OEF (9). Subsequently, Kuroda et al (8) have also revealed that OEF was significantly elevated in about 40% of type 3 patients.…”

Section: Discussionmentioning

confidence: 96%

“…Many earlier studies have evaluated the relationships between OEF and CVR (8,9,13,14). Most of these studies have concluded that there is a significant correlation between OEF and CVR to acetazolamide (13,14).…”

Section: Discussionmentioning

confidence: 99%

“…However, recent studies have shown that reduced CVR does not always represent elevated OEF. According to studies by Kuroda et al and Nemoto et al, only about half of the patients with reduced CVR had an elevated OEF (8,9). Based on these results, therefore, Kuroda et al (8) concluded that type 3 ischemia, which is defined as a reduced cerebral blood flow (CBF) and CVR (10), includes 2 pathophysiologically different conditions: misery perfusion due to hemodynamic compromise and matched hypometabolism due to incomplete infarction (8).…”

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confidence: 99%

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Combination of a Mean Transit Time Measurement with an Acetazolamide Test Increases Predictive Power to Identify Elevated Oxygen Extraction Fraction in Occlusive Carotid Artery Diseases

Hokari

Kuroda²,

Shiga³

et al. 2008

J Nucl Med

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Reduced cerebral blood flow and cerebrovascular reactivity to acetazolamide have been used as predictors for subsequent ischemic stroke in patients with occlusive carotid artery diseases, called type 3 ischemia. However, recent studies have shown that reduced cerebrovascular reactivity to acetazolamide does not always represent elevated oxygen extraction fraction (OEF). The aim of this study was to establish the methodology to improve the validity of an acetazolamide test identifying elevated OEF. Methods: This study included 65 patients who developed transient ischemic attack or minor completed stroke attributable to occlusive carotid artery diseases. Hemodynamic and metabolic parameters in the bilateral middle cerebral artery territories were determined in all patients by 15 O-gas PET. Results: Type 3 ischemia alone had 100% sensitivity and 83.2% specificity for identifying elevated OEF, but its positive predictive value and accuracy were low, 47.2% and 0.85, respectively. However, type 3 ischemia and delayed mean transit time combined had an 83.3% positive predictive value and 0.96 accuracy. Conclusion: The results strongly suggest that type 3 ischemia and delayed mean transit time together may be powerful predictors in identifying elevated OEF with high sensitivity and specificity, predictive values, and accuracy. SPECT may be able to define the patients with elevated OEF more easily and at lower costs than PET, although further study would be necessary to compare the results by using SPECT.

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“…Recent studies demonstrated that decreases in CVR and increases in OEF did not necessarily parallel each other. [63][64][65] PET measurements have been useful in demonstrating reversals of altered OEF because patients improve brain flow through collaterals 66 and following superficial temporal-to-MCA anastomoses. 67,14 Controlled studies to assess the value of OEF determinations for selection of therapy in patients with carotid occlusive disease are needed to determine the utility of these techniques.…”

Section: Asl Mr Perfusionmentioning

confidence: 99%

The Acetazolamide Challenge: Techniques and Applications in the Evaluation of Chronic Cerebral Ischemia

Vagal¹,

Leach²,

Fernández-Ulloa³

et al. 2009

AJNR Am J Neuroradiol

159

116

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SUMMARY:The acetazolamide (ACZ) challenge test is a useful clinical tool and a reliable predictor of critically reduced perfusion. In patients with chronic steno-occlusive disease, the ability to maintain normal cerebral blood flow by reducing vascular resistance secondary to autoregulatory vasodilation is compromised. Identification of the presence and degree of autoregulatory vasodilation (reflecting the cerebrovascular reserve) is a significant prognostic factor in patients with chronic cerebrovascular disease. The pharmacologic challenge of a vasodilatory stimulus such as ACZ can also be used to optimize the treatment strategies for these patients. The pathophysiology, methods, and clinical applications of the ACZ challenge test are discussed in this article. Viability of the cerebral parenchyma is dependent on the ability of the brain vasculature to provide adequate levels of cerebral blood flow (CBF). In patients with chronic stenoocclusive disease, the ability to maintain normal CBF by reducing vascular resistance is compromised. Identification of the degree of autoregulatory vasodilation reflects cerebrovascular reserve (CVR), which is a significant prognostic factor in chronic cerebrovascular disease.1-5 Flow reserve can be assessed with the use of paired blood flow measurements, with the initial measurement obtained at baseline and the second, after a vasodilatory stimulus, such as acetazolamide (ACZ). 6 Pathophysiology of Chronic Cerebrovascular DiseaseChronic cerebral hypoperfusion is usually the result of occlusion or stenosis of large arteries in the neck or the circle of Willis. Clinical symptoms and manifestations of brain ischemia in patients with chronic cerebrovascular disease (CVD) develop as a consequence of 2 main mechanisms: embolic events from atherosclerotic plaques resulting in local compromise of blood flow and systemic hemodynamic alterations that further reduce an already compromised cerebral perfusion state. 7The hemodynamic changes due to a decline in cerebral perfusion pressure have been studied by many investigators. 6,[8][9][10][11] Chronic CBF restriction causes a progressive decrease in cerebral perfusion pressure (CPP). Initially, decreases of CPP cause varying degrees of autoregulatory vasodilation of small distal arterioles.12 Powers 10 and Powers et al 11 proposed a 2-stage classification of hemodynamic impairment in patients with CVD. In stage I (autoregulatory vasodilation), autoregulation reduces cerebral vascular resistance. CBF and oxygen extraction fraction (OEF) are not significantly changed. Increases of cerebral blood volume (CBV) and mean transit time (MTT) are 2 parameters that reflect this initial phase of compensatory autoregulatory vasodilation. Further decreases of CPP beyond cerebral autoregulatory vasodilation capacity eventually result in stage II (autoregulatory failure), characterized by decreases of CBF and increases of OEF. When the CBF decreases, neurons increase the fraction of oxygen extracted from the blood to maintain normal neurologic function. ...

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Identification of Hemodynamic Compromise by Cerebrovascular Reserve and Oxygen Extraction Fraction in Occlusive Vascular Disease

Cited by 68 publications

References 37 publications

Significance of the perfusion‐diffusion mismatch in chronic cerebral ischemia

Significance of the perfusion‐diffusion mismatch in chronic cerebral ischemia

Combination of a Mean Transit Time Measurement with an Acetazolamide Test Increases Predictive Power to Identify Elevated Oxygen Extraction Fraction in Occlusive Carotid Artery Diseases

The Acetazolamide Challenge: Techniques and Applications in the Evaluation of Chronic Cerebral Ischemia

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