Fortin-Pellerin Etienne, Khoo Nee S, Coe James Y, Mills Lindsay, Cheung Po-Yin, Hornberger Lisa K
Division of Neonatology, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC, Canada.
Fetal and Neonatal Cardiology Program, University of Alberta, Edmonton, AB, Canada.
Front Pediatr. 2020 Jun 25;8:346. doi: 10.3389/fped.2020.00346. eCollection 2020.
Post-natal maturation of the myocardium starts shortly after birth and could affect how clinicians should provide hemodynamic support during this transition. Our aim was to assess the impact of post-natal maturation on tolerance to tachycardia with altered loading condition in a piglet model. We report three series of experimentations. Six groups of landrace cross neonatal piglets (NP) (1-3 days) and young piglets (YP) (14-17 days) were assigned to tachycardia (NP, YP), tachycardia and hypervolemia (NPV, YPV) or tachycardia and increased afterload (NPA, YPA) groups ( = 7/group). Under anesthesia, a pressure catheter was placed in the left ventricle and pacing wire in the right atrium. NPV and YPV groups had 60 ml/kg of normal saline infused over 20 min. NPA and YPA had balloon sub-occlusion of the descending aorta. Heart rate was increased by 10 bpm increments to 300 bpm. Left ventricular output was measured by echocardiography. NP maintained left ventricular output throughout the pacing protocol but it decreased in the YP ( < 0.001). With volume loading both NPV and YPV maintained their output with tachycardia. Although increased afterload resulted in reduced output during tachycardia in NPA ( = 0.005), there was no added impact on output in YPA. Interestingly, 4 of 7 NPV had significant desaturation at 300 bpm (baseline 99.7% vs. 300 bpm 87.9%, = 0.04), associated with a right to left shunt through the patent foramen ovale which resolved immediately on cessation of pacing. Early post-natal maturation is associated with improved myocardial tolerance to increased afterload and poor tolerance of tachycardia, the latter of which may be alleviated by increasing intravascular volume. These data could translate into the development of better strategies to optimize cardiac output at these early development ages.
心肌的产后成熟在出生后不久就开始了，这可能会影响临床医生在这一过渡阶段提供血流动力学支持的方式。我们的目的是在仔猪模型中评估产后成熟对改变负荷条件下心动过速耐受性的影响。我们报告了三组实验。将六组长白杂交新生仔猪（NP）（1 - 3日龄）和幼龄仔猪（YP）（14 - 17日龄）分为心动过速组（NP、YP）、心动过速合并高血容量组（NPV、YPV）或心动过速合并后负荷增加组（NPA、YPA）（每组n = 7）。在麻醉下，将压力导管置于左心室，起搏电极置于右心房。NPV组和YPV组在20分钟内输注60 ml/kg生理盐水。NPA组和YPA组对降主动脉进行球囊部分阻断。心率以每次增加10次/分钟的幅度增加至300次/分钟。通过超声心动图测量左心室输出量。NP在整个起搏过程中维持左心室输出量，但YP中的左心室输出量下降（P < 0.001）。容量负荷时，NPV组和YPV组在心动过速时均维持其输出量。尽管后负荷增加导致NPA组心动过速期间输出量减少（P = 0.005），但YPA组对输出量没有额外影响。有趣的是，7只NPV中有4只在300次/分钟时出现明显的血氧饱和度下降（基线99.7% vs. 300次/分钟时87.9%，P = 0.04），这与通过卵圆孔未闭的右向左分流有关，起搏停止后立即消失。产后早期成熟与心肌对后负荷增加的耐受性提高以及对心动过速的耐受性差有关，后者可通过增加血管内容量得到缓解。这些数据可能会转化为在这些早期发育阶段优化心输出量的更好策略的制定。
