Rodríguez-Fernández Jairo Armando, Almazán-Soo Arturo
Servicio de Cardiología Hospital General de Zona Núm. 24, IMSS, México DF, México.
Arch Cardiol Mex. 2005 Jul-Sep;75 Suppl 3:S3-106-12.
Persistent left superior vena cava (PLSVC) is a structural, asymptomatic and infrequent anomaly, present in 0.5% of the general population. Typically the diagnosis reveals itself unexpectedly at the time of pacemaker implantation, when it acquires anatomic relevancy. Several techniques are used for the transvenous approach to enter the central venous circulation; the left subclavian vein has become a common access site for electrode implantation and, occasionally, one can find an anomalous venous structure such as a PLSVC. Placement of electrodes through this anomalous venous structure can prove challenging, if not impossible. The present report tries to explore aspects of transimplantation diagnosis from a practical point of view. It also address the knowledge of anatomy, implant technique and radiographic orientation.
Twenty-six-year-old woman with confirmed Symptomatic Sick Sinus Syndrome variety Sinus Arrest. The diagnosis of PLSVC was discovered unexpectedly at the time of the transvenous approach. The tip for the diagnosis was the "unusually medial" position of the lead, and the venogram showed the venous traject towards the coronary sinus and drainage into the right atrium. An active-fixation screw-in electrode was positioned in the antero-superior margin of the free wall of the right atrium. After 24 months of successful placement of the pacemaker, the patient is asymptomatic.
PLSVC is a rare congenital vascular abnormality. Besides its association with congenital anomalies, its most relevant clinical implication is the association with disturbances of cardiac rhythm, impulse formation and conduction. The ontogenetic development of the sinus node, the atrioventricular node, and the His bundle might be heavily influenced by the lack of regression of the left cardinal vein. When isolated, the PLSVC is usually not recognized until left superior approach to the heart is required, when it becomes a relevant anatomic finding. In fact, it can complicate the positioning of left-sided pacemaker and cardioverter-defibrillator leads. In patients with poor handling through the coronary sinus, a right approach is recommended after visualization of a right superior vena cava entering the right atrium by echocardiography or contrast venography since its absence or hypoplasia (which is reported in 10% of the cases with PLSVC) may represent a major obstacle and would suggest an epicardial implantation.
Today, the preferred approach for pacemaker lead implantation is via the left subclavian vein and the operator must be aware of this venous anomaly that may technically complicate the electrode positioning. This kowledge may be useful for other medical specialties that require the implant of left sided transvenous subclavian catheters, like in critical care settings, nephrology, onco-hematology, and anesthesiology.
永存左上腔静脉（PLSVC）是一种结构上无症状且罕见的异常情况，在普通人群中的发生率为0.5%。通常在植入起搏器时意外发现该诊断，此时它具有解剖学相关性。有几种技术用于经静脉途径进入中心静脉循环；左锁骨下静脉已成为电极植入的常见入路部位，偶尔会发现异常静脉结构，如PLSVC。通过这种异常静脉结构放置电极可能具有挑战性，甚至无法完成。本报告试图从实际角度探讨经植入诊断的各个方面。它还涉及解剖学知识、植入技术和影像学定位。
一名26岁女性，确诊为有症状的病态窦房结综合征中的窦性停搏类型。在经静脉途径时意外发现了PLSVC的诊断。诊断线索是导线“异常偏内侧”的位置，静脉造影显示静脉走向冠状窦并引流至右心房。将主动固定螺旋电极置于右心房游离壁的前上缘。起搏器成功植入24个月后，患者无症状。
PLSVC是一种罕见的先天性血管异常。除了与先天性异常有关外，其最相关的临床意义是与心律失常、冲动形成和传导障碍有关。窦房结、房室结和希氏束的个体发育可能会受到左主静脉未退化的严重影响。当单独存在时，PLSVC通常在需要从左侧接近心脏时才被识别，此时它成为一个相关的解剖学发现。实际上，它会使左侧起搏器和心脏复律除颤器导线的定位复杂化。对于经冠状窦操作困难的患者，在通过超声心动图或造影静脉造影显示右上腔静脉进入右心房后，建议采用右侧入路，因为其缺失或发育不全（在10%的PLSVC病例中报告）可能是一个主要障碍，并提示需要进行心外膜植入。
如今，起搏器导线植入的首选途径是经左锁骨下静脉，操作者必须意识到这种静脉异常可能会在技术上使电极定位复杂化。这一知识可能对其他需要植入左侧经静脉锁骨下导管的医学专科有用，如在重症监护、肾脏病学、肿瘤血液学和麻醉学领域。
