br Discussion PLSVC can be
Discussion PLSVC can be encountered for the first time during electrophysiological procedures. It is the most common variation in the thoracic venous system and is estimated to be present in 0.3–0.5% of the general population and in 5–10% of patients with other congenital heart defects . It can be accompanied by other congenital venous anomalies . Several PLSVC subtypes are recognized. About 20% of patients do not have a right superior vena cava (RSVC), which results in venous blood drainage from the head and both arms through the left brachiocephalic vein, PLSVC, and coronary sinus into the RA. However, most patients have an RSVC. In 60% of cases, the PLSVC and RSVC are connected by a communicating branch (left brachiocephalic vein) . Therefore, approximately 50% of PLSVC cases have a venous branch communicating between the PLSVC and RSVC. ICD lead implantation through a PLSVC is often challenging and sometimes unsuccessful . It can prolong fluoroscopic and procedural times, and the loop on the lead across the tricuspid valve can result in higher mechanical stress, making it prone to lead failure. This case illustrates an alternative approach for ICD lead implantation in a patient with a PLSVC. Our findings suggest that a PLSVC system should be carefully inspected for any communicating branches that can be utilized for lead implantation in order to increase the chance of success and minimize the risk of complications. The above-mentioned anatomical findings may also encourage this strategy.
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Case presentation She had acute cholecystitis that was operated on urgently, 3h before her new substernal and epigastric pain appeared. She also had ceterizine and hypertension. Her drug history included losartan, hydrochlorothiazide, metformin, and atorvastatin. A 12-lead ECG revealed negative P wave and Q and ST segment elevation in leads II, III, and aVF, and ST depression in leads V4–V6 (Fig. 1). The repeated ECG showed the same abnormalities. Emergent bed side echocardiography showed an ejection fraction of 40%, mild diastolic dysfunction, inferior and posterior wall hypokinesia, and mild mitral regurgitation. Her hemodynamics was stable. Cardiac and lung examinations produced unremarkable results.
Commentary According to the sinoatrial node position (right upper part of the right atrium) and the propagation of the electrical impulse in the atriums during the normal sinus rhythm, the P wave will be positive in leads I, II, V5, and V6, and will be negative in lead aVR . However, owing to the possibility of other nonsinus rhythms, presence of situs abnormalities, and presence of atrial abnormalities, the use of P wave morphology alone can be difficult for detecting lead misplacement. Evaluating the orientation of the vectors in each lead in standard 12-lead ECG can offer a guide for this purpose. As shown in Fig. 2, when the limb and precordial leads are placed in their standard location, the aVR and V5 or V6 leads are in the same alignment but have deflections in the opposite polarity; thus, these leads are in a reciprocal relation to each other. As the positive pole for augmented leads is the exploring electrode, in this ECG the augmented lead that can be the true aVR lead is the aVF, which has a negative P and QRS, reciprocal to V6 . This means that the left leg lead was connected to the right arm. This is possible if the left leg lead is switched with the right arm lead (more probable), or there is a clockwise rotation error. After coronary angiography, we reviewed our ECG again. Because of some abnormal P waves in leads II, III, and aVF, we ordered a repeat ECG; during the ECG, we observed that the right hand and left leg leads were connected inversely. The leads were connected to their standard locations on the extremities, and the repeated ECG revealed no significant Q and ST segment elevation in the inferior leads (Fig. 3). This case emphasizes the importance of misplacement of ECG leads on the clinical impression. Misplacement of right arm with left leg is a rare event that could mimic Q wave myocardial infarction in inferior leads . Misplacement of ECG leads has been reported to mimic a variety of false abnormalities, including Q wave myocardial infarction, low voltage (indicative of pericardial effusion), and ST elevation [4,5].