编者按：对大多数冠状动脉病变介入治疗以正向技术为首选，对少数病情严重、正向技术无法获益时，也可选择逆向技术，两种途径均无法避免并发症。在第二十六届国际长城心脏病学会议上，印度孟买导管室医学顾问Debabrata Dash教授对上述问题做了讲解。

　　International Circulation：Welcome Dr. Dash. My first question is antegrade wire technology and retrograde wire technology can both be applied in treating CTOs. What are the indications of these two technologies respectively and how do you evaluate these two technologies?

　　如何评价正向&逆向技术

　　Dash：Thank you for the invitation. As you know， as far as the complexity is concerned CTO sits at the top of the mountain. There are two types of approaches; antegrade approach and retrograde approach. Antegrade approach is the mainstay of CTO treatment and preferred in first time CTO， CTO with microchannels， short segment CTO， CTO without calcium or less calcium， and when there is a broad landing zone. Retrograde PCI can be applied in cases of failure of the antegrade technique. That is reason number 1. Number 2 is when the antegrade approach is hopeless， like long occlusion CTO with heavy calcium， a RCA bend point CTO， these are called the primary retrograde approach. In order to evaluate this technique we have to do a study that is in hospital death or with clinical outcome at one year and follow up with death MI and target lesion revascularization.

　　Like I said most of the procedures can be tackled with the antegrade approach but however when the artery is very torturous and calcified or the CTO is very long it may lead to failure. The complications can also occur with antegrade approach like dissection， that is the aorta coronary dissection， which is one of the most dreaded complications. Another complication is perforation. Regarding the retrograde approach， the process when antegrade approach fails we can apply this as a second procedure or it can be because of the primary indications I have mentioned already. However it is not without complications like there may be septal hematoma， septal rupture， and here also we can have guided catheter and nerve dissection and perforations but with experience these complications may be minimized or negligible.

　　慢性完全闭塞（CTO）病变非常复杂，治疗方法有正向及逆向两种技术。目前，正向技术是无微通道、短节段及无钙化/钙化较少的CTO治疗首选，但当正向技术治疗失败时，可采用逆向技术。要想评价两种技术的优劣，需开展相关研究随访观察并比较两者对院内死亡及术后1年心肌梗死和靶病变血运重建等临床结局的影响。

　　大部分CTO介入手术可通过正向技术来完成，但对严重钙化或长病变CTO，正向技术介入成功率低。此外，正向技术可出现主动脉/冠状动脉夹层、穿孔等严重并发症。虽然在正向技术治疗失败时可选用逆向技术，但逆向技术也存在鼻中隔血肿、室间隔破裂、导管/神经夹层及穿孔等并发症。不过，如术者经验丰富，上述风险可忽略。

　　International Circulation：My next question is compared with post operative complications， intraoperative complications of PCI are usually more critical. Could you please share something about the prevention and treatment of PCI intraoperative complications?

　　PCI术中并发症防治经验

　　Dash：Intraoperative complications are mainly dissection， perforation， air embolism， and no reflow. Sometimes there is stent and device problems. Regarding so many types of dissection - aortic， coronary dissections is a direct complication but the incidence is less than 1%. It could be caused by guiding catheter trauma including disengagement of the guide and it is mainly occurs with the right coronary artery as compared to the left. When you inject the contrast medium in the coronary artery it may happen. It may be due to shearing forces during systole and diastole. It is caused by as I said already， guiding catheter trauma， small RCA， extensive sclerosis， hypertension， and recent MI. This dissection can be classified into 3 types. Type 1 involves the distal cap， type 2 is distal cap to the ascending aorta that is 40mm， type 3 involves aortic caps that is more than 40mm. Type 1 and 2 dissection can be minimized by minimizing of contrast injection and sealing of the anterior point of the dissection with the conventional stent or covered stent. Type 3 dissection requires surgery. Another complication is perforation and perforation can also be classified into 3 types. Type 1 there is extraluminal crater without contrast and extravasation. Type 2 is myocardial or pericardial burst without contrast extravasation and type 3 is contrast extravasation through 1mm perforation. For type 1 perforation basically watch for expectancy is enough. Type 2 perforations is managed by prolonged balloon inflation， reversal of the anticoagulation， and sometimes we have to embolize the artery with gel foam microcoil， clot subcutaneous， and fibrin. Type 3 is the most dangerous kind of perforation， it may lead to death so here also we can apply prolonged balloon inflation， reversal of the anticoagulation， and sometimes we may have to deploy a cover stent and many patients go to surgery as well. As you know another complication is air embolism. It occurs in 0.3% of the PCI cases， patients present with chest pain， ST segment elevation， bradycardia， hypotension， asystole and ventricular fibrillation. Small air into the coronary does not lead to hemodynamic consequences so you can leave it like that， however when there is air lock we have to give intravenous fluids， atropine， vasopressors， we have to use IABP sometimes， then air bubble disruption with wire or balloon catheter expression， sometimes forceful injection of the selenium contrast may have to be applied. Sometimes what happens during PCI is the stent gets dislodged and there is an embolism. If the stent is small and embolized very thoroughly we may leave it like that however we may have to deploy it if it is on the wire and if it is off the wire we may have to cross it， sometimes we need snare to retrieve it. Another way to take out the stent is by twisting of the wire. As you know prevention is better than cure so ideally we must try to prevent these complications from happening by knowing the detailed procedures， anatomy， indications， contraindications， and sometimes we have to take precautions from the very beginning to avoid these dreaded complications.

　　PCI术中并发症主要包括夹层、穿孔、空气栓塞及无复流，还包括支架及设备相关问题。夹层包括主动脉夹层、冠状动脉夹层等多种类型，但发生率不足1%。冠状动脉夹层更多发于右冠，导管所致创伤、广泛硬化、高血压及近期心肌梗死等均可引发夹层。夹层可分为Ⅰ型、Ⅱ型和Ⅲ型，前两者可通过减少造影剂用量和采用传统支架或覆膜支架封闭处理，后者需手术治疗。穿孔也可分为三种类型，其中Ⅰ型穿孔只需密切监测，Ⅱ型穿孔需延长球囊扩张时间、逆转抗凝，有时甚至需用明胶海绵等进行堵塞。Ⅲ型穿孔最危险，可能会导致死亡，需延长球囊扩张时间和立即逆转抗凝，有时还需置入覆盖支架，甚至接受手术治疗。空气栓塞发生率为0.3%，患者常伴胸痛、ST段抬高、心动过缓、低血压、心搏骤停及室颤。少量空气进入冠状动脉不会导致严重的血液动力学后果，无需处理；但当出现空气栓塞时，应给予静脉输液、阿托品及升压药物，必要时进行主动脉球囊反搏。支架脱落方面，若支架较小、栓塞不严重可不处理，否则需重新放置或取出。

　　因此，就PCI术中并发症而言，防胜于治。临床实践中，医生应充分了解并掌握手术过程、患者解剖特征、适应证和禁忌证，适时采取预防性措施积极预防术中并发症。