ABSTRACT
AIMS: The aim of this study is to measure the effect of positive-pressure ventilation on heart chamber dimensions, left ventricular (LV) systolic function, LV diastolic function, right ventricular (RV) systolic function, and RV pressure using transthoracic echocardiography. SETTINGS AND DESIGN: This is a prospective study in a single secondary health-care center. MATERIALS AND METHODS: A total of 107 patients with obstructive sleep apnea on continuous positive airway pressure (CPAP) therapy were recruited as participants between April and September 2016. Transthoracic echocardiography was performed twice on each participant, before and 15 min after, they used their own CPAP machines, and the echocardiography parameters of both scans were compared. STATISTICAL ANALYSIS USED: The parametric paired t-test was used to compare heart chamber dimensions, left heart diastolic function, left heart systolic function, right heart systolic function, and right heart pressure effect, without and with CPAP. These data were further examined among several subgroups defined by CPAP when the cutoff point was set at 8 cmH2O and 10 cmH2O. The level of significance was set at 0.05. Statistical analyses were performed using IBM SPSS version 22 (IBM, Armonk, NY, USA). RESULTS: There were statistically significant reductions, after the application of CPAP, in the heart dimensions, and LV and RV systolic function. There were no significant changes in diastolic function. Concerning right heart pressure, with CPAP, there was a significant increase in the inferior vena cava (IVC) diameter and there was also a significant decrease in IVC variability from 44.56% ± 14.86% to 36.12% ± 11.42%. The maximum velocity of tricuspid regurgitation (TR) decreased significantly from 180.66 ± 6.95 cm/s to 142.30 ± 52.73 cm/s. Such changes were observed in both low and high CPAP subgroups. CONCLUSIONS: When placed on positive pressure, the clinically significant change in IVC diameter and variability and change in trans-TR velocity mean that it would be inaccurate to predict right heart chamber pressure through echocardiogram. Alternative methods for predicting right heart pressure are recommended.
ABSTRACT
BACKGROUND: With extraction of cardiovascular implantable electronic devices (CIED) increasingly necessitated, various studies have contemplated to investigate clinical predictors for its success and complications. Intrinsic parameters of CIED leads have been studied less extensively and are the foci of this study. METHODS: Three major pacemaker manufacturers accepted invitation. Leads then underwent tensile test in vitro with their composite tensile strength (TS) compared. Mechanism of yielding, under tensile stress, was also observed among them. RESULTS: All pacing leads, participated in this study, surpassed requirement of European Standard EN 45502-2-1. Boston Scientific's FINELINE II STEROX 4456/52 cm (Boston Scientific Corp., St. Paul, MN, USA) and Medtronic's CAPSURE SENSE 4074/52 cm (Medtronic, Minneapolis, MN, USA) showed similar composite TS and both were stronger compared with St. Jude Medical's ISOFLEX OPTIM 1948/52 cm (P <0.001; St. Jude Medical, Sylmar, CA, USA). Despite a difference in the exact site, the Medtronic 4074 and St. Jude Medical 1948 yielded similarly in that their distal tip electrode remained connected with a flimsy inner coil to proximal portion of the lead after their composite TS was exceeded. Boston Scientific 4456's insulation tubing and coil wire broke almost simultaneously and separated completely from the tip electrode when it yielded. CONCLUSIONS: FINELINE II STEROX 4456/52 cm and CAPSURE SENSE 4074/52 cm showed stronger composite tensile strength than ISOFLEX OPTIM 1948/52 cm. FINELINE II STEROX 4456 was found more prone to complete severance. Limitations and precautions to translate these differences directly into real-life scenario are discussed.
