动静脉畸形处理的现代理念

动静脉畸形（AVM）为先天性血管畸形（CVMs），可发生于身体任何部位，因动脉、静脉发育缺陷所致，造成不同大小血管之间的直接交通，或者发育不良的小血管形成原始血管网，不能成熟发育为毛细血管而称为异常血管团（nidus）。其特征是通过不同的瘘，血液经动脉结构直接流入静脉系统，流速快，阻力低。不同专家组制订的系统分类（Hamburg分类，ISSVA分类，Schobinger分类和血管造影分类）使我们对AVM的生物学特性和自然病程有了更多了解，治疗效果显著提高。Hamburg分类基于胚胎发育，分为躯干外和躯干2类，有助于确定病变的发展和复发可能。大多数AVM为躯干外型，具有持续增殖潜力，而躯干型AVM十分罕见。不论哪种类型，动静脉分流最终会导致严重解剖、病理生理和血流动力学改变。AVM可分为动静脉瘘（AVF，Ⅰ型）、异常血管团型（nidus，Ⅱ型）、静脉动脉瘤样扩张型（静脉动脉瘤样扩张伴多条供血动脉，单条回流静脉增粗，Ⅲa型；静脉动脉瘤样扩张伴多条供血动脉，多条回流静脉增粗，Ⅲb型）和浸润型（diffuse infiltration，Ⅳ型）4种类型，尽管临床少见（占CVM的10％～20%），AVM仍然是最具挑战性、危及生命或致残的血管畸形。

AVM的临床表现取决于病变范围和大小，可为无症状胎记，也可伴充血性心力衰竭。初步诊断和评估可依据无创或微创检查如双功能超声、MRI、MRA、CT和CTA。动脉造影是AVM诊断的金标准，也是制订后续治疗所必需的。多学科团队处理应联合手术和非手术干预，以获得最佳疗效。目前可用的治疗手段具有很高的并发症风险，但如评估利大于弊，应早期给予积极治疗，消灭异常血管团（如有的话）。经动脉弹簧圈栓塞或结扎供应动脉是错误的治疗，异常血管团仍然完整，可导致病变发展加重，而且这种处理会妨碍进一步经动脉途径进行介入治疗。不能手术切除、浸润型躯干外AVM可单纯采用血管内介入治疗。在各种栓塞治疗中，无水乙醇栓塞可获得最佳的远期疗效，复发最少，但操作者需要经过系统培训和足够经验，以最大限度地减少并发症。对于可手术切除的病变，可采用手术治疗，以获得对病变的良好控制。术前栓塞可减少术中出血，缩小病变和确定病变边界，有利于手术切除，这种联合治疗有望获得最好的治愈效果。

The Yakes classification system: Type I is a direct arteriovenous fistula, a direct artery to vein connection (typified by Pulmonary AVF and renal AVF, for example. Type II is AVM characterized by usually multiple in-flow arteries into a “nidus” pattern with direct artery-arteriolar to vein-venular structures that may, or may not, be aneurysmal. Type IIIa is multiple arteries-arterioles into an enlarged aneurysmal vein with an enlarged single out-flow vein. Type IIIb is multiple arteriesarterioles into an enlarged aneurysmal vein with multiple dilated out-flow veins. Type IV is microfistulous innumerable arteriolar structures to innumerable venular connections that diffusely infiltrate a tissue (typified by, ear AVMs that infiltrate the entire cartilage of the pinna).

Yakes type I: Can be permanently occluded, with mechanical devices such as coils, fibered coils, Amplatzer Plugs, and other occluding devices.

Yakes type II: Can be permanently occluded with undiluted absolute ethanol. At times slowing the arterial in-flow in the “nidum” with occlusion balloons, tourniquets, blood pressure cuffs, does allow for less ethanol to be used to treat the AVM compartments. Direct puncture techniques into the in-flow artery or AVM “nidum” allow ethanol to embolize the AVM as well.

Yakes type IIIa: Can be permanently occluded with transarterial embolizations with ethanol of the “nidum” the same way as in the Yakes type II AVM. They can also be permanently occluded by dense coil packing of the vein aneurysm with or without ethanol embolization. This can be accomplished via direct puncture of the vein aneurysm, or by retrograde vein catheterization of the vein aneurysm. Yakes Type IIIb: Can be permanently occluded via transarterial approach as in Yakes Type II AVMs. They can be permanently occluded by treating the vein aneurysm and the multiple aneu-rismal out-flow veins by coil embolization.

Yakes type IV: Can be permanently occluded via transarterial superselective 50% mixture of non-ionic contrast and ethanol that treats the micro-AVFs and spares the higher resistance capillaries. Direct puncture with 23gauge needles into the micro fistulous AV connections with 50% ethanol injections is also curative.

参考文献

Yakes WF, Yakes AM. The Yakes classification of arteriovenous malformations. The 40th Annual Veith Symposium Presentation, November 19, 2013.

Lee BB, Baumgartner I, Berlien HP, Bianchini G, Burrows P, Do YS, Ivancev K, Kool LS, Laredo J, Loose DA, Lopez-Gutierrez JC, Mattassi R, Parsi K, Rimon U, Rosenblatt M, Shortell C, Simkin R, Stillo F, Villavicencio L, Yakes W; International Union of Angiology. Consensus Document of the International Union of Angiology (IUA)-2013. Current concept on the management of arterio-venous management. Int Angiol, 2013,32(1):9-36.