Sampson S N, Tucker R L, Bayly W M
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman 99164-6610, USA.
Equine Vet J Suppl. 1999 Jul(30):190-4. doi: 10.1111/j.2042-3306.1999.tb05216.x.
We evaluated the relationships of heart score (HS) and echocardiographic measures to maximal oxygen consumption (VO2max), maximal cardiac output (Qmax), and maximal stroke volume (SVmax). Six fit, mature Thoroughbred horses weighing (mean +/- s.e.) 487 +/- 11 kg were run 4 times on an inclined (10%) treadmill. Each run consisted of a 3 min warm-up at 4 m/s followed by completion of an incremental exercise test in which each horse ran until VO2max was reached. Arterial and mixed venous blood was collected to determine arteriovenous oxygen content difference C(a-v)O2[ in the last 15 s of exercise. An ATL HDI 3000 ultrasound system and a 3.5 MHz phased array transducer were used to make echocardiographic measurements before and within 2 min of run completion. Guided M-mode echocardiographic measurements of left ventricular diameter (LVD), interventricular septal thickness (IVS) and left ventricular free wall thickness (LVFW) during diastole (D) and systole (S) were made from the right parasternal short axis view at the level of the chordae, and VO2 and C(a-v)O2 were measured as the appropriate M-mode view was recorded. Maximum heart rate (HRmax) was determined using a cardiotachometer, and HS was calculated on nonexercise days using the established technique. Maximum cardiac output and SVmax were calculated from the Fick equation and HRmax. Backward stepwise regression analysis was used to relate pre- and post exercise echocardiographic measurements and HS to VO2, Q, and SV at the time of measurement, and to VO2max, Qmax, and SVmax. Pre- and post exercise LVDD appeared to be the most important variable in these equations. Mean pre-exercise HR at the time of measurement was 54.7 +/- 1.9 beats/min, while the mean post exercise rate was 111.7 +/- 2.6 beats/min. The mean +/- s.e. VO2max was 150.4 +/- 13.2 ml/(kg.min). Heart score was not correlated with VO2max, Qmax, or SVmax. There was no significant difference between pre- and post exercise measurements of LVD, IVSS, and LVFWS.
我们评估了心脏评分（HS）及超声心动图测量指标与最大耗氧量（VO2max）、最大心输出量（Qmax）和最大每搏输出量（SVmax）之间的关系。六匹健康、成熟的纯种马，体重（均值±标准误）为487±11千克，在倾斜度为10%的跑步机上跑4次。每次跑步包括以4米/秒的速度进行3分钟热身，随后完成递增运动试验，每匹马一直跑到达到VO2max。在运动的最后15秒采集动脉血和混合静脉血，以测定动静脉氧含量差C(a-v)O2。在跑步结束前及结束后2分钟内，使用ATL HDI 3000超声系统和3.5兆赫相控阵探头进行超声心动图测量。从右胸骨旁短轴切面在腱索水平进行舒张期（D）和收缩期（S）左心室直径（LVD）、室间隔厚度（IVS）和左心室游离壁厚度（LVFW）的M型超声心动图测量，并在记录适当的M型视图时测量VO2和C(a-v)O2。使用心率计测定最大心率（HRmax），并在非运动日采用既定技术计算HS。根据Fick方程和HRmax计算最大心输出量和SVmax。采用向后逐步回归分析，将运动前后的超声心动图测量值和HS与测量时的VO2、Q和SV以及VO2max、Qmax和SVmax相关联。运动前后的左心室舒张末期内径（LVDD）似乎是这些方程中最重要的变量。测量时运动前的平均心率为54.7±1.9次/分钟，而运动后的平均心率为111.7±2.6次/分钟。VO2max的均值±标准误为150.4±13.2毫升/（千克·分钟）。心脏评分与VO2max、Qmax或SVmax均无相关性。运动前后LVD、IVSS和LVFWS的测量值之间无显著差异。
