====== Collateral artery formation ======

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Collateral artery formation refers to the development of new [[blood vessel]]s in response to [[occlusion]] or [[stenosis]] (narrowing) of a major blood vessel. This compensatory mechanism helps to maintain [[blood flow]] to [[tissue]]s that would otherwise be deprived of [[oxygen]] and [[nutrient]]s, by providing alternative [[pathway]]s for [[blood]] to reach those areas. Collateral artery formation occurs in response to various conditions such as ischemic heart disease, peripheral arterial disease, and [[stroke]].
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[[Collateral artery formation]] from the extracranial [[carotid artery]] to ischemic [[brain tissue]] determines the clinical success of [[Superficial temporal artery to middle cerebral artery bypass for moyamoya disease]] in adult patients, but postoperative collateral formation (PCF) after STA-MCA bypass surgery is unpredictable. Accurate [[preoperative]] [[prediction]] of acceptable PCF could improve patient selection. 
Sun et al. from the [[West China Hospital]], aimed to develop a [[prediction]] nomogram model for PCF in this patient [[population]].

[[Adult patient]]s with [[moyamoya disease]] undergoing the STA-MCA bypass surgery between January [[2013]] and December [[2020]] at a single [[institution]] were [[retrospective]]ly or [[prospective]]ly enrolled in this [[observational study]]. [[Data]] including potential clinical and radiological [[predictor]]s were obtained from hospital [[record]]s. A [[nomogram]] was generated based on a [[multivariate]] [[logistic regression]] [[analysis]], to identify potential [[predictor]]s associated with good PCF. The performance of the [[nomogram]] was evaluated for [[discrimination]], [[calibration]], and clinical utility.

Data from 243 patients with [[moyamoya disease]] who underwent the STA-MCA bypass surgery were analyzed to build the nomogram. After 1-year follow-up, 162 (66.7%) hemispheres had good PCF and 81 (33.3%) had poor PCF. Good PCF is associated with 3 preoperative factors: [[age]] at operation, the diameter of the donor branch of STA, and the preinfarction period stage. Incorporating these 3 factors, the model achieved a [[concordance]] index of 0.88 (95% CI, 0.84-0.92) and had a well-fitted calibration curve and good clinical application value. A cutoff value of 100 was determined to predict good PCF via this nomogram.

The [[nomogram]] exhibits high accuracy in predicting good PCF after the STA-MCA bypass surgery in adult patients with [[moyamoya disease]] and may allow surgeons to better evaluate preoperatively candidacy for successful [[bypass surgery]]
((Sun H, Li Y, Xiao A, Li W, Xia C, You C, Ma L, Liu Y, Xia C. [[Nomogram]] to Predict Good Collateral Formation After the [[STA]]-[[MCA]] [[Bypass Surgery]] in [[Adult Patient]]s With [[Moyamoya Disease]]. Stroke. 2023 Feb 7. doi: 10.1161/STROKEAHA.122.039975. Epub ahead of print. PMID: 36748463.)).