Patel J J, Dyer R B, Mitha A S
Department of Cardiology, University of Natal/Wentworth Hospital, Durban, South Africa.
Eur Heart J. 1995 Sep;16(9):1264-8. doi: 10.1093/oxfordjournals.eurheartj.a061084.
This study was designed to assess the effects of beta-blockade on cardiopulmonary exercise performance in symptomatic patients with tight mitral stenosis in sinus rhythm.
The role of beta-blockers in these patients has been controversial and assessment of effort tolerance using treadmill exercise time has produced conflicting results.
Nineteen patients with isolated symptomatic (New York Heart Association class II or III) mitral stenosis received a beta-blocker (acebutalol or atenolol) or matching placebo for one week each in a randomized double-blind crossover fashion. Exercise on a treadmill with real time gas exchange analysis was performed six times over 4 weeks in each patient. The test was further repeated once within a week of percutaneous mitral valvotomy.
Heart rate at rest and during peak exercise was significantly lower with beta-blockade compared to control state or placebo treatment. Mean peak oxygen consumption did not differ significantly between treatment groups. When patients were arbitrarily classified into those with (group I, heart rate < or = 130.min-1) and those without (group II, heart rate > or = 131.min-1) adequate beta-blockade, there was a significant difference in peak VO2. The peak VO2 for group I: 14.0 +/- 3.2 vs 17.5 +/- 4.0 ml.min-1.kg-1; peak VO2 for group II: 17.2 +/- 2.4 vs 18.0 +/- 2.4 ml.min-1.kg-1 (beta-blockade vs control state respectively). Treadmill exercise time did not differ between treatment groups. The slope of minute ventilation (MV) and carbon dioxide (CO2) excretion, and instantaneous carbon dioxide ventilatory equivalent (MV/VCO2) was unchanged with beta-blocker therapy indicating no improvement in ventilatory performance.
Beta-blocker therapy in tight mitral stenosis appears to have no beneficial effect on aerobic capacity, nor does it improve ventilatory performance. Adequate beta-blockade may adversely effect peak oxygen consumption.
本研究旨在评估β受体阻滞剂对窦性心律的症状性二尖瓣狭窄患者心肺运动表现的影响。
β受体阻滞剂在这些患者中的作用一直存在争议，使用跑步机运动时间评估运动耐力产生了相互矛盾的结果。
19例孤立性症状性（纽约心脏协会II或III级）二尖瓣狭窄患者以随机双盲交叉方式接受β受体阻滞剂（醋丁洛尔或阿替洛尔）或匹配的安慰剂治疗，各为期1周。每位患者在4周内进行6次跑步机运动并进行实时气体交换分析。在经皮二尖瓣球囊成形术一周内再次进行该测试。
与对照状态或安慰剂治疗相比，β受体阻滞剂治疗时静息心率和运动高峰时心率显著降低。各治疗组间平均峰值耗氧量无显著差异。当患者被任意分为β受体阻滞剂阻滞充分组（I组，心率≤130次/分钟）和阻滞不充分组（II组，心率≥131次/分钟）时，峰值VO₂有显著差异。I组峰值VO₂：14.0±3.2 vs 17.5±4.0 ml·min⁻¹·kg⁻¹；II组峰值VO₂：17.2±2.4 vs 18.0±2.4 ml·min⁻¹·kg⁻¹（分别为β受体阻滞剂治疗组与对照状态）。各治疗组间跑步机运动时间无差异。β受体阻滞剂治疗时分钟通气量（MV）和二氧化碳（CO₂）排出量的斜率以及瞬时二氧化碳通气当量（MV/VCO₂）未改变，表明通气性能未改善。
二尖瓣狭窄患者使用β受体阻滞剂治疗似乎对有氧运动能力无有益影响，也不能改善通气性能。充分的β受体阻滞剂阻滞可能对峰值耗氧量产生不利影响。
