Department of Health Sciences, Mid Sweden University, Östersund, Sweden.
Institute for Signal Processing and Speech Communication, Graz University of Technology, Graz, Austria.
J Appl Physiol (1985). 2023 Apr 1;134(4):951-956. doi: 10.1152/japplphysiol.00708.2022. Epub 2023 Feb 24.
Syncope or "blackout" (BO) in breath-hold diving (freediving) is generally considered to be caused by hypoxia. However, it has been suggested that cardiac arrhythmias affecting the pumping effectivity could contribute to BO. BO is fairly common in competitive freediving, where athletes aim for maximal performance. We recorded heart rate (HR) during a static apnea (STA) competition, to reveal if arrhythmias occur. Four male freedivers with STA personal best (PB) of 349 ± 43 s, volunteered during national championships, where they performed STA floating face down in a shallow indoor pool. A non-coded Polar T31 chest strap recorded R-R intervals and a water- and pressure-proof pulse oximeter arterial oxygen saturation. Three divers produced STA near their PB without problems, whereas one diver ended with BO at 5 min 17s, which was 12 s beyond his PB. He was immediately brought up by safety divers and resumed breathing within 10 s. All divers attained similar lowest diving HR (47 ± 4 beats/min), but HR recordings displayed a different pattern for the diver ending with BO. After a short tachycardia, the three successful divers developed bradycardia, which became more pronounced during the second half of the apnea. The fourth diver developed pronounced bradycardia earlier, and at 2.5 min into the apnea, HR started alternating between approximately 50 and 140 beats/min, until the diver lost consciousness. At resumed breathing, HR returned to baseline. Nadir oxygen saturation was similar for all divers. We speculate that arrhythmia could have contributed to BO, by lowering stroke volume leading to a systolic blood pressure drop, affecting brain perfusion. Heart rate during prolonged breath-holding until the point of loss of consciousness has not previously been published. The recordings show that blackout was preceded by a period of persistent alterations in R-R intervals, whereby an ectopic beat followed every normal heartbeat. Explanations for this deviating heart rate pattern could be either premature atrial contractions or premature ventricular contractions following every atrial beat, i.e., bigeminy, which could have compromised cardiac pumping function and caused/contributed to blackout.
屏气潜水（自由潜水）中的晕厥或“黑视”（BO）通常被认为是由缺氧引起的。然而，有人认为影响泵血效果的心律失常也可能导致 BO。BO 在竞技自由潜水中相当常见，运动员的目标是达到最佳表现。我们在一次静态闭气（STA）比赛中记录了心率（HR），以揭示是否存在心律失常。四名男性自由潜水员在全国锦标赛中自愿参加，他们在浅室内游泳池中面朝下漂浮进行 STA。 Polar T31 胸部带记录 R-R 间隔，水密和压敏脉搏血氧仪记录动脉血氧饱和度。三名潜水员在接近个人最好成绩（PB）的情况下进行了 STA，没有出现问题，而一名潜水员在 5 分 17 秒时出现了 BO，比 PB 超时 12 秒。他立即被安全潜水员救出，并在 10 秒内恢复呼吸。所有潜水员的最低潜水 HR（47±4 次/分钟）都相似，但出现 BO 的潜水员的 HR 记录显示出不同的模式。在短暂的心动过速之后，成功的三名潜水员发展为心动过缓，在闭气的后半段变得更加明显。第四名潜水员更早地出现明显心动过缓，在闭气 2.5 分钟时，HR 开始在大约 50 和 140 次/分钟之间交替，直到潜水员失去意识。在恢复呼吸时，HR 恢复到基线。所有潜水员的最低血氧饱和度相似。我们推测心律失常可能通过降低每搏输出量导致收缩压下降，从而影响脑灌注，导致 BO。之前没有发表过在意识丧失之前长时间闭气的心率。这些记录显示，在 BO 之前，RR 间隔持续出现改变，即每一次正常心跳之后都会出现异位搏动。这种异常心率模式的解释可能是心房每搏后出现房性期前收缩或室性期前收缩，即二联律，这可能会影响心脏泵血功能，并导致/导致黑视。
