Currently we are unable to fully understand the diversity an
Currently, we are unable to fully understand the coelenterazine and distribution of the AT arising around the apex of the triangle of Koch. Koyama et al. closely studied the spatial and topographic variation in the distribution of this type of AT around the His-bundle . As demonstrated in the present case, detailed electrophysiologic evaluation in relation to each anatomic structure should be attempted in each case. Attempts should be made to identify areas where concealed entrainment can be demonstrated, followed by a detailed systematic analysis of PPI and stimulus-P and local electrogram-P intervals; this might enable the precise determination of the size and orientation of the microreentry circuit.
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Introduction The conventional method of pacemaker implantation via the subclavian vein is sometimes unfeasible in cases of occlusion and tortuosity of the vein accompanied by superior vena cava (SVC) obstruction. SVC obstructions are generally caused by malignancies (80–90%) and various benign conditions (20%). The most common benign causes of the SVC obstruction are central venous catheters or pacemaker/defibrillator leads, while a rare cause is thoracic aortic aneurysm . Herein, we report a rare case in which VVI pacemaker implantation was achieved via the less invasive femoral vein approach in an elderly patient with a thoracic aortic aneurysm.
Case report The patient also had hypertension, an abdominal aortic aneurysm (diameter, 71mm), and a thoracic aortic aneurysm (diameter, 64mm; Fig. 1). These aortic aneurysms had been treated conservatively. She was not taking any medicine capable of causing atrioventricular block, and her serum electrolyte levels were normal. Given these findings, she was considered eligible for placement of a permanent pacemaker. First, we attempted VVI pacemaker implantation through the left subclavian vein approach. Contrast angiography, however, revealed left brachiocephalic vein occlusion, and a wire and pacemaker lead could not be advanced into the heart (Fig. 2A). We then attempted to implant the pacemaker via the right subclavian vein. However, a 7-Fr sheath became kinked because the origin of the right subclavian vein was very tortuous and narrow (Fig. 2B and C). A sheath-in-sheath system, which included a 7-Fr sheath inside a 9-Fr sheath, also failed to maintain the patency of the sheath. The procedure was as follows. Under local anesthesia, we incised the skin above the inguinal ligament around the femoral vein (Fig. 3), detached the intimal tissue, and stripped the ligament. After puncturing the lower portion of the ligament to enter the femoral vein, we inserted a 7-Fr split-sheath system for introducing a pacemaker lead and guided the lead into the right ventricle. In order to advance the lead to the right ventricle, we inserted the stylet curved to 180° in a long ventricular lead (CapsureFix Novus, 5076/85cm, Medtronic). After the lead was advanced into the right atrium, we pulled the stylet off and bent it again such that its tip was oriented toward the patient\'s back; we then inserted it again and screwed the lead in at the lower portion of the right ventricular septum (Fig. 3). We sutured the inguinal ligament to fix the lead and prevent hemorrhage. To hold the unit in place, a pouch was fashioned cranial to the incision and superficial to the fascia of the external oblique abdominal muscle. A tunnel from the ligament point to the pouch was made by clipping. After the tip of the lead was inserted into the pouch and connected to a pulse generator (Adapta, Medtronic), they were advanced into the pouch, and the wound was sutured. The entire procedure lasted 89min, with minimal intraoperative hemorrhage.
Discussion Occasionally, conventional access sites for pacemaker implantation are not available, and another approach must be selected according to the patient\'s clinical condition, medical history, and/or background. Epicardial lead placement under general anesthesia may be an alternative, but was considered to be too invasive for this inactive, elderly patient who had 2 aortic aneurysms with sizes greater than 60mm and under conservative management. The transvenous approach from either the internal or external jugular vein could have solved this problem, but in this case, only the right internal jugular vein was usable due to the abnormality of the superior vein. If venous thrombosis or restenosis occurs at this implantation site, the patient could develop face edema, headache or dizziness, and symptoms of SVC syndrome [2–4]. Taking the above points into consideration, we chose a trans-IVC approach (Fig. 4).