彩色多普勒在阳萎诊断中的应用

用彩色多普勒血流显像配合罂粟碱试验观察２６例阳萎阴茎深动脉峰值流速（Ｖｐ）、舒张末期最小流速（Ｖｍｉｎ）。结果表明：对罂粟碱反应良好１２例，反应低下１４例，Ｖｐ分别为３７．８±７．６ｃｍ／ｓ及２７．６±５．９ｃｍ／ｓ（Ｐ＜０．０１），取９５％可信限，Ｖｐ大于３ｋｍ／ｓ可认为动脉功能正常。反应低下中６例有海绵体静脉疹，８例为动脉供血不足，二者Ｖｐ分别为３４．２±６．１ｃｍ／ｓ及２１．２±５．８ｃｍ／ｓ（Ｐ＜０．０１），Ｖｍｉｎ分别为７．６±２．４ｃｍ／ｓ及２．２±１．１ｃｍ／ｓ（Ｐ＜０．０１）。动脉供血不足者Ｖｐ均小于３０ｃｍ／ｓ。多普勒超声不仅能区别血管性与非血管性阳萎，而且对血管性阳萎中的动脉供血抑或静脉机能不全有所提示。影响流速测值的因素有：仪器类型、探头频率，是否采用角度校正以及注药后流速测定的时间。     

经尿道汽化和电切治疗前列腺增生症262例

采用３种汽化电极经尿道汽化术（ＴＵＶＰ）结合电切术（ＴＵＲＰ）治疗前列腺增生症２６２例。结果：手术时间２０～８０ｍｉｎ,平均３５ｍｉｎ;平均灌洗量４５００ｍｌ;切除组织重量２０～７０ｇ,平均３５．２ｇ。随访１～２５月,ＩＰＳＳ由术前（３０．１±２．９）分降至术后（１３．８±１．１）分（Ｐ＜０．０１）。ＭＦＲ由术前（６．４±２．７）ｍ／ｓ升至术后（１５．１±１．９）ｍｌ／ｓ（Ｐ＜０．０１）。残余尿（ＲＨ）由术前（１５０±６０．３）ｍｌ降至术后（４５．１±１８．５）ｍｌ（Ｐ＜０．０５）。该文探讨了ＴＵＶＰ和ＴＵＲＰ联合治疗ＢＰＨ的具体方法,认为该术式可减少电切综合征,增加高危ＢＰＨ患者手术机会,免做膀胱造瘘,减轻了患者痛苦。     

参麦注射液治疗老年心力衰竭疗效观察

目的：探讨参麦注射液治疗老年心力衰竭的临床疗效。方法：４０例住院老年心力衰竭患者,在卧床休息、限盐、使用强心剂和利尿剂等综合治疗基础上,随机分为治疗组（加用参麦注射液４０～６０ｍｌ＋５％葡萄糖２５０ｍｌ静滴,每日１次）与对照组（加口服卡托普利１２．５～２５．０ｍｇ,每日３次）各２０例,以１０日为１个疗程。观察２组治疗对心功能、症状、体征的影响和不良反应。结果：第１疗程后治疗组总有效率７０．０％,第２疗程后为９４．４％;而对照组分别为４５．０％与５８．８％（Ｐ＜０．０５和Ｐ＜０．０１）;第２疗程治疗组心率、心率与血压乘积指数较治疗前降低〔分别由（８４．５０±１０．５０）次／ｍｉｎ和１２１．８０±１８．２０降到（７０．７６±９．２０）次／ｍｉｎ和９５．５１±１０．２０,Ｐ＜０．０５和Ｐ＜０．０１〕,对照组略有下降（Ｐ均＞０．０５）;治疗组未见不良反应。结论：参麦注射液治疗老年心力衰竭安全有效,并随着疗程延长可进一步改善心功能,达到标本兼治     

负荷超声心动图检测暂时性心肌缺血的试验研究

本文对３６只冠脉临界狭窄的杂种犬施行了定量潘生丁负荷超声心动图试验（ＤＳＥＴ）。动物分为３组：小剂量（潘生丁０．５ｍｇ／ｋｇ／４ｍｉｎ，静注），大剂量组（潘生丁１．０ｍｇ／８ｍｉｎ，静注）。和对照组（生理盐水１０ｍｌ／４ｍｉｎ，静注用药前、后连续记示两维超声心动图（２ＤＥ），平均主动脉压（ＭＡＰ）、心率（ＨＲ）、左室舒张末期压（ＬＶＥＤＰ）、远端冠脉压（ＤＣＰ）和节段性冠脉阻力（ＳＣＲ），并同时观察ＥＣＧ。结果显示：大剂量潘生丁注射后，ＭＡＰ从１３．４±０．８下降到１０．６±１．０ｋＰａ（Ｐ＜０．０５）；ＨＲ略有减低（Ｐ＜０．０５），ＤＣＰ明显减少（下降３０～３５％），ＣＢＦ减少超过４０％，２ＤＥ可检出局部室壁运动异常（ＲＷＭＡ）；而在小剂量组，ＤＣＰ仅下降１０～２０％，ＣＢＦ增加１０～２０％，而ＨＲ无明显变化（Ｐ＞０．０５）。结论：冠脉临界狭窄时，由于ＣＢＦ和ＳＣＲ对定量潘生丁试验呈双向变化，所以，小剂量潘生丁不能诱发明显的ＲＷＭＡ，而大剂量潘生丁注射后，２ＤＥ即可检出明显的一过性心肌缺血。     

经尿道前列腺汽化术治疗前列腺增生

为了探讨经尿道前列腺汽化术（ＴＶＰ）的治疗效果,６７例前列腺增生患者施行了ＴＶＰ。汽化的前列腺平均重量５７．６ｇ,手术平均时间４１ｍｉｎ,术中出血量２０～１２０ｍｌ。４２例病人获得１个月和３个月的随访,结果显示：前列腺症状评分从术前（１７．６±５．３）降至（５．９±２．１）和（４．２±１．３）,最大尿流率从术前的（７．４±３．０）ｍｌ／ｓ增加到（１５．３±２．８）ｍｌ／ｓ和（１７．３±１．４）ｍｌ／ｓ,剩余尿由术前（５７±２０）ｍｌ降至（３７±１１）ｍｌ和（４３±９）ｍｌ。ＴＶＰ具有疗效显著、并发症少等特点,并提出了ＴＶＰ注意事项。     

脉冲多普勒对颈总动脉不同节段收缩期最大血流速度测量的影响

目的：采用脉冲多普勒于颈总动脉不同节段测量一组健康人（ｎ＝２０）收缩期最大血流速度，旨在探讨不同取样位置对颈总动脉血流速度测量的影响。方法：采用７．５ＭＨｚ探头沿颈总动脉进行纵向扫查完整显示其管腔长轴，固定探头使图像稳定。于距离颈动脉球部近心端１、２、３、４、５ｃｍ处取样测量血流速度，取样容积大小和角度校正保持恒定。结果：距离颈动脉球部１、２、３、４、５ｃｍ处最大血流速度分别为６９．１±１３．８ｃｍ／ｓ、７７．２±１６．５ｃｍ／ｓ、８４．４±１６．６ｃｍ／ｓ、９１．５±２０．１ｃｍ／ｓ、７７．１±１９．３ｃｍ／ｓ（Ｐ＜０．０５）。取样位置由１ｃｍ移至４ｃｍ血流速度平均增幅７．３５ｃｍ／ｓ；取样位置由４ｃｍ移至５ｃｍ处，血流速度平均降幅为１４．１ｃｍ／ｓ。距颈动脉球３ｃｍ处血流速度变异系数最小（ＣＶ＝０．１９）。结论：取样位置由颈总动脉球部向近心端移动，血流测值并不相同。其中距颈总动脉球部３ｃｍ处血流速度测值较为恒定准确，选择此处作为颈总动脉多普勒测量标准取样位置使超声诊断颈内动脉狭窄等血管病变更为客观、标准     

韩氏穴位神经刺激仪（HANS）对75例海洛因戒断者心率的影响

本研究根据一定频率的电刺激可促使中枢神经系统释放阿片肽的原理，应用韩氏穴位神经刺激仪（ＨＡＮＳ），治疗７５例海洛因戒断者，观察到ＨＡＮＳ对海洛因戒断者的心动过这具有明显的抑制作用。每日刺激１次，在首次治疗的５ｍｉｎ后，心率即开始下降，由治疗前的１０９±３次／分降至１０３±２．５次／分；至１０ｍｉｎ时心率降至９８±１．６次／分，与对照组相比有显著性差异（Ｐ＜０．０１）；至３０ｍｉｎ时心率下降为９１±１．４次／分（Ｐ＜０．００１）。连续治疗４天以后，心率可稳定在正常水平（７２±１．１～８２±１．５次／分之间）。     

卡托普利合并复方丹参治疗糖尿病肾病20例疗效观察

用卡托普利合并复方丹参治疗２０例糖尿病肾病患者，治疗前血压为２４．５±０．７／１１．３±０．４ｋＰａ（１８４．２±５．３／８４．８±３．０ｍｍＨｇ），治疗后为１９．２±０．７／１０．２±０．４ｋＰａ（１４４．０±５．５／７６．５±３．０ｍｍＨｇ），Ｐ＜０．０１；血尿素氮治疗前后分别为８．５３±０．７８ｍｍｏｌ／Ｌ和６．６５±１．３８ｍｍｏｌ／Ｌ，Ｐ＜０．０１；血肌酐治疗前后分别为１４３．１７±３．８５μｍｏｌ／Ｌ和１２０．２１±４．５１μｍｏｌ／Ｌ，Ｐ＜０．０１；尿蛋白定量治疗前后分别为１．９０±０．３０ｇ／２４ｈ和１．１２±０．４２ｇ／２４ｈ，Ｐ＜０．０５。结果表明：二药合用确能降低血压，减少尿蛋白排出及改善肾功能，值得临床推广应用。     

依那普利治疗轻中度原发性高血压的临床疗效观察

本文将８３例轻中度原发性高血压患者进行单盲分组对照试验。治疗组益压利４２例，对照组怡那林４１例。益压利组５～２０ｍｇ／次，每日１次。６周后坐位ＢＰ由２３．２±２．０／１３．１±０．８降至１９．８±１．２／１１．６±０．７ｋＰａ，立位ＢＰ由２３．０±１．９／１３．０±０．８降至１９．４±１．０／ｌｌ．５±０．７ｋＰａ，其降压临床显效率４７．６％，总有效率９０．５％。怡那林组５～２０ｍｇ／次，每日１次，６周后坐位ＢＰ由２３．３±２．０／１３．１±０，８降至２０．８±１．２／１２．３±０．７ｋＰａ，立位ＢＰ由２３．０±２．０／１３．１±０．８降至２０．６±１．０／１２．２±０．７ｋＰａ，其显效率３４．１％，总有效率８２．９％。结果表明两组均有明显降压效果，但两组间临床总有效率无显著性差异（Ｐ＞０．０５）。而２４小时ＡＢＰ谷：峰（Ｔ／Ｐ）比值显示，益压利组ＳＢＰ为８１．７％，ＤＢＰ为７６．０％，优于怡那林组的５０．８％及４４．１％。     

男性冠心病患者血清性激素变化及其意义的探讨

应用放免法测定了４０例确诊男性冠心病患者与４０名健康人血清睾酮（Ｔ），雌二醇（Ｅ２），并同步检测其血清胆固醇，甘油三酯及高密度脂蛋白，旨在探讨性激素在男性冠心病发病中的作用及可能机理。结果为冠心病组Ｔ值（１５．０４±４．８６ｎｍｏｌ／Ｌ），显著低于对照组（２０．４５±９．２６），Ｐ＜０．０１；Ｅ２（１７３．２０±９５．１２／１００．５３±４９．８２ｐｍｏｌ／Ｌ）、Ｅ２／Ｔ比值（１１．０３±６．９７／５．７７±４．２３）均显著高于对照组（Ｐ均＜０．０１）。同时冠心病组血清胆固醇较对照组明显增高（５．３０±０．９４／４．３９±１．０５，Ｐ＜０．０１），高密度脂蛋白胆固醇（ＨＤＬ－Ｃ）尤其是ＨＤＬ２低于对照组。其中胆固醇浓度与Ｔ呈负相关（ｒ＝０．３８２８，Ｐ＜０．０５），与Ｅ２及Ｅ２／Ｔ比值呈正相关（ｒ＝０．４７９９，Ｐ＜０．０５；ｒ＝０．３５，Ｐ＜０．０５）。提示：性激素失衡在男性冠心病发病中可能起一定作用，可能与其致血脂代谢异常有关。     

Comparison of heart rate responses. Water walking versus treadmill walking

The purpose of this study was to compare heart rate responses to water walking versus treadmill walking to determine whether the responses were of sufficient magnitude to elicit cardiorespiratory training effects. The heart rates of 12 healthy, female college students were measured immediately after walking in waist-deep water and on a treadmill at the same distance, durations, and speeds (2.55, 2.77, 3.02, and 3.31 km/hr). A significant increase in heart rate with increased speeds resulted from water walking (p less than .05); from rest to the fastest speed, it was 135% (96 bpm). For treadmill walking, the increase of 19% (13 bpm) was not significant. The heart rates for the water condition were significantly higher (p less than .05) at each speed. These findings indicate that water walking could serve as an effective exercise mode, for example, for cardiorespiratory fitness for individuals who are unable to perform such weight-bearing activities as jogging, fast walking, cycling, and dancing.     

BOSU球与平板练习对脑卒中患者下肢功能疗效的比较

目的比较BOSU球和平板运动对脑卒中患者下肢功能康复的影响。方法40 例脑卒中患者(病程>6 个月)随机分为BOSU球组(n=20)和平板组(n=20),分别在常规康复的基础上进行BOSU球和平板练习。治疗前和治疗12 周后,分别采用Berg 平衡量表(BBS)、30 s 坐站试验(CS-30)、坐位体前屈(SR)、6 min 步行试验(6MWT)、改良Barthel 指数(MBI)对患者进行评定。结果治疗后,两组患者各项评定均较运动前改善(P<0.05),BOSU球组BBS及MBI评分较平板组改善更多(P<0.05)。结论BOSU球运动能更有效提高脑卒中患者的平衡能力和日常生活活动能力。     

不同有氧运动方式对健康人心肺适能影响的研究

目的:本研究旨在比较两种不同有氧锻炼方式对健康人心肺适能水平的影响。方法:将32名健康受试者随机分到跑步平台组和楼梯机组各16名,2组受试者分别进行跑步机及楼梯机有氧锻炼,每次30min,每天1次,共5d。结果:锻炼后,楼梯机组第1秒用力呼气容积(FEV1)、FEV1/FVC、最大通气量(MVV)、呼气峰流速(PEF)以及6min步行距离(6MWD)均较锻炼前明显提高(P<0.05),用力肺活量(forced vital capacity,FVC)比较差异无统计学意义;跑步平台组锻炼后FVC、FEV1、FEV1/FVC、6MWD、PEF较锻炼前明显提高(P<0.05),MVV变化差异无统计学意义。锻炼后,楼梯机组FEV1/FVC、MVV、6MWD、PEF提高幅度明显优于跑步平台组(P<0.05),但FVC、FEV1的提高幅度差异无统计学意义。结论:楼梯机锻炼和跑步平台锻炼对健康人的心肺适能水平都有显著影响,但楼梯机锻炼对健康人的MVV、FEV1/FVC、PEF及6MWD的提高幅度更大,即楼梯机锻炼在短时间内对健康人的心肺适能水平影响更显著。     

Metabolic cost of extremely slow walking in cardiac patients: implications for exercise testing and training

To assess metabolic cost of extremely slow walking, nine patients with coronary heart disease (means age, 56.1 yr) underwent multistage treadmill testing using standard open circuit calorimetry techniques. Heart rate, blood pressure, minute ventilation, and oxygen uptake in METS (1MET = 3.5 ml/kg/min) were determined at rest and at six submaximal work loads: 0.8, 1.0, 1.5, 2.0, 3.0 and 3.5mph, 0% grade. The oxygen uptake versus walking speed (0.8 to 3.5mph) relationship was y = 0.2064 (x)2 + 0.0180 (x) + 1.7260 (y = METS and x = speed in mph), r = 0.99. Results indicate that low-level exercise test protocols employing work loads between 0.8 and 2.0 mph impose similar metabolic and cardiac demands. Extremely slow walking approximates 2METS and may impose metabolic loads sufficient for exercise training in select patients with coronary heart disease.     

Reproducibility of treadmill exercise in patients with intermittent claudication

Summary. The reproducibility of pain limited exercise time (ET) and heart rate (HR) have been evaluated in repeated treadmill exercise tests in 24 patients with arterial occlusive disease of the lower limbs and intermittent claudication. The protocol includes a walking speed of 1 m/s and load increments of 10 watt/min and the two tests were separated by 1–14 days. The total ET was systematically increased by about 30 sec (.P<0–05) at the second exercise test. The reproducibility of ET at the onset of leg pains was 34%, whereas the corresponding value at maximal leg pain was 16%. HR at the termination of the test did not differ systematically between the two tests and the reproducibility of HR was 61% and 5-5% at the onset of pain and maximal pain, respectively. It is concluded that a slight improvement in walking capacity at a second exercise test must be taken into account when evaluating different types of therapy in patients with intermittent claudication and, furthermore, that ET, walking distance or work load, should preferably be evaluated at or near maximal leg pain.     

The effects of added prosthetic mass on physiologic responses and stride frequency during multiple speeds of walking in persons with transtibial amputation

OBJECTIVES: To determine the effect of 3 prosthetic mass conditions on selected physiologic responses during multiple speed treadmill walking in persons with transtibial amputation. DESIGN: A repeated-measures design for 3 prosthetic mass conditions and 5 walking speeds. SETTING: University research laboratory. PARTICIPANTS: Eight ambulatory men with unilateral traumatic transtibial amputation. INTERVENTIONS: The 3 prosthetic mass conditions were 60%, 80%, and 100% of the estimated intact limb below-knee mass. The multiple-speed treadmill walking test (4min at each speed: 54, 67, 80, 94, 107m/min) was performed on an instrumented treadmill according to randomly assigned mass conditions. MAIN OUTCOME MEASURES: Oxygen consumption, gait efficiency, relative exercise intensity (percentage of age-predicted maximal heart rate), and stride frequency. RESULTS: Prosthetic mass did not significantly alter oxygen consumption or gait efficiency (P>.05). From the 60% to the 100% prosthetic mass conditions, relative exercise intensity significantly increased and stride frequency significantly decreased (P<.05). CONCLUSIONS: A heavier prosthesis (up to 100% of estimated intact limb below-knee mass) did not significantly increase the energy costs of walking for the 5 speeds examined. Further study of gait symmetry with the use of a heavier prosthesis is warranted.     

Benefits and Limitations of Rate Adaptive Pacing Under Laboratory and Daily Life Conditions in Patients with Minute Ventilation Single Chamber Pacemakers

Rate adaptive pacing has been shown to improve hemodynamic performance and exercise tolerance during acute testing. However, there remain concerns about its benefit in daily life and possible complications incurred by unnecessary pacing. This double-blind crossover study compared the benefit of rate adaptive (SSIR) versus fixed rate (SSI) pacing under laboratory and daily life conditions in 20 rate incompetent patients with minute ventilation single chamber pacemakers (META II). The heart rate (HR) response during three different exercise tests (treadmill, bicycle ergomctry, walking test) was correlated with the Holler findings during daily life in either pacing mode. The maximal HR was significantly higher in the SSIR-mode compared to the SSI-mode, both during laboratory testing (treadmill: 123 ± 15 vs 93 ± 29 beats/min: ergometry: 118 ± 15 vs 89 ± 27 beats/min; walking test: 127 ± 9 vs 95 ± 26 beats/min, all P values < 0.01) as well as during daily life (Holter: 126 ± 13 vs 103 ± 24 beats/min, P < 0.01). On Holter, the average HR (71 ± 14 vs 71 ± 8 beats/min) and the percentage of paced rhythm (54 % vs 62%, SSI- vs SSIR-mode, P = NS) were not different in either mode. However, despite a 30% rate gain in the SSIR-mode, the exercise capacity remained unchanged, and only 38% of patients preferred the SSIR-mode. Minute ventilation pacemakers provide a physiological rate response to exercise. Irrespective of the protocol used, the findings of laboratory testing are comparable to those during daily life. However, patient selection for rate adaptive single chamber pacing should be made with caution, since the objective benefit of restoring normal chronotropy may subjectively be negligible for most patients.     

The Effects of a Complex Exercise Program with the Visual Block on the Walking and Balance Abilities of Elderly People

[Purpose] The purpose of this study was to investigate the effect of a complex exercise program for elderly people who had experienced a fall on their balance, gait, vestibular senses, and proprioceptive senses when their visual sense was blocked. [Subjects and Methods] The subjects were 30 healthy elderly people aged 65 or older. They were equally and randomly divided into a visual block (VB) group (those whose eyes were covered) and a visual permission (VP) group. The subjects performed the complex exercise program for 30 minutes, twice a day, five day a week for 4 weeks a total of 20 times. Outcome measures were the10 meter walking test (10MWT), stair up/down test (SUDT), Berg balance scale (BBS), vestibular stepping test (VST), proprioception test (PT). [Results] After the intervention, the VB group showed improvements in 10MWT, VST, and PT. The VP group showed improvements in 10MWT and PT. The significant improvement in VST observed in the VB group was significantly greater than that in the VP group. [Conclusion] The complex exercise program for elderly people helped enhance their balance ability and gait, and improved their vestibular sense.Key words: Complex exercise, Elderly, Visual block     

Abnormal cardiovascular response to exercise in patients with peripheral arterial disease: Implications for management

Exercise is beneficial in improving claudication and functional capacity in patients with peripheral arterial disease (PAD). However, the physiologic response during and after exercise testing in this patient population has not been fully described. This study examined the cardiovascular response to exercise and explored the potential contribution of vascular noncompliance to exercise-induced hypertension in 124 patients with PAD and claudication and 31 comparison (C) patients with PAD with no walking limitations. Maximal walking distance was determined by an exercise treadmill test. Heart rate and blood pressure were monitored before, during, and immediately after an exercise test. Vascular compliance of the small and large vessels was measured using pulse waveform analysis. Individuals with low supine resting heart rate had longer pain-free walking distance (r = -0.195, P = .019) and maximal walking versus the C group (62 beats/min, standard deviation [SD] = 10, P = .02). Systolic blood pressure during supine rest was significantly lower for the PAD group (mean = 141 mm Hg, +/- SD = 22) versus the C group (mean = 153 mm Hg, +/- SD = 20, P = .003). Vascular compliance of large vessels was higher in the C group (mean = 4.13 +/- 4.13 mL/mm Hg x 100) compared with the PAD group (mean = 2.95 +/- 1.6 mL/mm Hg x 100). This study describes the exaggerated exercise cardiovascular response and impaired vascular compliance in patients with PAD. These results provide further evidence supporting the importance of a monitored treadmill exercise test before initiation of an exercise program to ensure safe and accurate exercise recommendations, and to identify individuals that require more intensive pharmacotherapy to prevent exercise-induced hypertension and tachycardia.     

Rate Adaptive Cardiac Pacing Using Right Ventricular Venous Oxygen Saturation: Quantification of Chronotropic Behavior During Daily Activities and Maximal Exercise

Central venous oxygen saturation (S_vO_z) closely reflects cardiac output and tissue oxygen consumption. In the absence of an adequate chronotropic response during exercise, S_vO₂ will decrease and the extent of desaturation maybe used as a parameter for rate adaptive cardiac pacing. Eight patients with sinoatrial disease received a DDDR pacemaker capable of DDDR pacing by sensing either S_VO₂ or piezoelectric detected body movement. Both sensors were programmed to attain a rate of about 100 beats/min during walking, and with the lower and upper rates set at 50% and 90% of age predicted maximum, respectively. Chronotropic behavior of the two sensors were compared in the DDD mode with measurement of sensor responses, during everyday activities (walking, stair climbing, postural changes, and physiological stresses) and at each quartile of workload during a continuous treadmill exercise test. During walking at 2.5 mph, both sensors showed no significant difference in delay time (both react within 15 sees) or half-time (S_VO₂= 36 ± 12 sec and activity 24 ± 3 sec; P = NS), although S_VO₂ driven pacing achieved 90% target rate response slowerthan activity sensing (124 ± 16 sec vs 77 ± 10 sec; P < 0.02). S_VO₂ pacing was associated with a more physiological rate response during walking upslope (68 ± 12 beats/min vs 57 ± 10 beats/ min; P < 0.05), ascending stairs (59 ± 10 beats/min vs 31 ± 6 beats/min; P < 0.05), and standing (34 ± 7 beats/min vs 9 ± 2 beats/min; P < 0.05). The S_vO₂ sensor significantly overpaced in the first quartile of exercise (51.8 ± 25.6% in excess of heart rate expected from workload), but the rate was within 20% of expected for the remainder of exercise. “Underpacing” was observed with the activity sensor at the higher workload. In conclusion, the S_vO₂ sensor demonstrated a more physiological response to activities of daily living compared with the activity sensor. Using a quantitative method, the speed of onset of rate response of the S_vO₂ sensor was comparable to activity sensing, and was more proportional in rate response. Significant overpacing occurs at the beginning of exercise during S_VO₂ driven pacing, which may be improved with the use of a curvilinear algorithm.