biostudies-literatureUnknown23(2)Albizreh BWe are reporting a case of a young Nepalese man, who was not known to have any past medical history, and who presented with palpitations. An electrocardiogram showed negative P-waves atrial rhythm in II, III, arteriovenous fistula, and V3-V6 with a variable block at 90-130 bpm. No positive "normal" P-waves were demonstrated in any tracing. He was found to have a congenital absence of the right superior vena cava (RSVC) along with persistent left superior vena cava (PLSVC) a condition also called isolated PLSVC (IPLSC). He underwent a treadmill stress test for further evaluation which showed a normal chronotropic response and the same persistent negative P-waves morphology. An invasive electroanatomical and activation mapping showed an absence of RSVC, the earliest atrial activation site inHeart views : the official journal of the Gulf Heart Association113-117https://www.ebi.ac.uk/biostudies/studies/S-EPMC9542964biostudies-literatureAn Ectopic Primary Pacemaker in Association with Isolated Persistent Left Superior Vena Cava.PMC9542964Al Jefairi NAlbizreh BHamid SAsaad NElmagraby AfalseAn Ectopic Primary Pacemaker in Association with Isolated Persistent Left Superior Vena Cava.We are reporting a case of a young Nepalese man, who was not known to have any past medical history, and who presented with palpitations. An electrocardiogram showed negative P-waves atrial rhythm in II, III, arteriovenous fistula, and V3-V6 with a variable block at 90-130 bpm. No positive "normal" P-waves were demonstrated in any tracing. He was found to have a congenital absence of the right superior vena cava (RSVC) along with persistent left superior vena cava (PLSVC) a condition also called isolated PLSVC (IPLSC). He underwent a treadmill stress test for further evaluation which showed a normal chronotropic response and the same persistent negative P-waves morphology. An invasive electroanatomical and activation mapping showed an absence of RSVC, the earliest atrial activation site in2022-01-01T00:00:00Z2022 Apr-Jun2025-04-25T17:36:26.176Z2025-04-06T05:04:48.746ZS-EPMC95429643621342610.4103/heartviews.heartviews_90_21