Time courses of central hemodynamics during rapid changes in posture.

Changes in posture cause blood volume redistribution, affecting cardiac filling and stroke volume (SV). We hypothesized that the time courses of ventricular filling would differ between the right and left ventricle during a rapid (2 s) tilt and that changes in right ventricular filling pressure would be more swift because of the direct coupling to the systemic circulation. We further hypothesized that the transient imbalance between right and left ventricular filling pressure would influence left ventricular SV changes. Right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP), left ventricular stroke volume, heart rate, and arterial pressure were recorded beat-by-beat during rapid tilts from supine to upright positions and back again, during rest and dynamic 100-W leg exercise. RAP changes had a faster time course than PCWP during down-tilts, both during rest and exercise (1 ± 1 vs. 6 ± 2 s and 2 ± 2 vs. 6 ± 2 s, respectively; P < 0.05). This discrepancy caused a transient decrease in the end-diastolic pressure difference between the right and left ventricle. The decreased pressure difference in diastole impeded left ventricular filling because of ventricular interdependence, causing SV to fall transiently. The mechanisms of ventricular interdependence were also involved in reverse during up-tilt, where SV was maintained for 2-3 s despite falling PCWP. Furthermore, the decrease in RAP during up-tilt in the resting condition was biphasic with an initial fast and a second slower component, which might suggest the effect of venous valves. This was not seen during dynamic leg exercise where blood pooling is prevented by the venous muscle pump.

Adenosine in cold blood cardioplegia--a placebo-controlled study.

OBJECTIVE Adenosine as an additive in blood cardioplegia is cardioprotective in animal studies, but its clinical role in myocardial protection remains controversial. The aim of this study was to investigate whether the addition of adenosine in continuous cold blood cardioplegia would enhance myocardial protection. METHODS In a prospective double-blind study comparing adenosine 400 µmol l(-1) to placebo in continuous cold blood cardioplegia, 80 patients undergoing isolated aortic valve replacement were randomized into four groups: antegrade cardioplegia with adenosine (n = 19), antegrade cardioplegia with placebo (n = 21), retrograde cardioplegia with adenosine (n = 21) and retrograde cardioplegia with placebo (n = 19). Myocardial arteriovenous differences in oxygen and lactate were measured before, during and after aortic occlusion. Myocardial concentrations of adenine nucleotides and lactate were determined from left ventricular biopsies obtained before aortic occlusion, after bolus cardioplegia, at 60 min of aortic occlusion and at 20 min after aortic occlusion. Plasma creatine kinase (CK-MB) and troponin T were measured at 1, 3, 6, 9, 12 and 24 h after aortic occlusion. Haemodynamic profiles were obtained before surgery and 1, 8 and 24 h after cardiopulmonary bypass. Repeated-measures analysis of variance was used for significance testing. RESULTS Adenosine had no effects on myocardial metabolism of oxygen, lactate and adenine nucleotides, postoperative enzyme release or haemodynamic performance. When compared with the antegrade groups, the retrograde groups showed higher myocardial oxygen uptake (17.3 ± 11.4 versus 2.5 ± 3.6 ml l(-1) at 60 min of aortic occlusion, P < 0.001) and lactate accumulation (43.1 ± 20.7 versus 36.3 ± 23.0 µmol g(-1) at 60 min of aortic occlusion, P = 0.052) in the myocardium during aortic occlusion, and lower postoperative left ventricular stroke work index (27.2 ± 8.4 versus 30.1 ± 7.9 g m m(-2), P = 0.034). CONCLUSIONS Adenosine 400 µmol l(-1) in cold blood cardioplegia showed no cardioprotective effects on the parameters studied. Myocardial ischaemia was more pronounced in patients receiving retrograde cardioplegia.

High intensity deep water training can improve aerobic power in elderly women.

Deep water running with wet vest is a safe form of exercise for elderly with mobility limitations. However, it is not known to what extent their aerobic power may be improved. Therefore, the aim was to assess the effects of high intensity deep water interval training with vest in elderly women. Twenty-nine healthy women 69 +/- 4 years old participated. They performed a graded maximal exercise test on the cycle ergometer. They were randomly assigned to a control or to a training group. A submaximal exercise test on the cycle ergometer was executed only by the training group. They trained in deep water running/walking wearing a vest two times a week for 8 weeks. The target heart rate was 75% of maximal heart rate and the training consisted of several short working periods and resting intervals. After the intervention the heart rate at rest was 8% lower for the training group (P<0.01). Their heart rate at submaximal exercise was 3% less (P<0.01), their maximal oxygen uptake was raised by 10% (P<0.01), and their maximal ventilation was increased 14% (P<0.01). The values for the control group were unaltered after the period of intervention. In conclusion, high intensity deep water running with vest improves submaximal work capacity, maximal aerobic power, and maximal ventilation with the effects transferable to land-based activities in elderly women.

Older women's cardiovascular responses to deep-water running.

The aim of the study was to examine submaximal and maximal physiological responses and perceived exertion during deep-water running with a vest compared with the responses during treadmill running in healthy elderly women. Eleven healthy women 70 +/- 2 years old participated. On two different occasions they performed a graded maximal exercise test on a treadmill on land and a graded maximal exercise test in water wearing a vest. At maximal work the oxygen uptake was 29% lower (p < .05), the heart rate was 8% lower (p < .05), and the ventilation was 16% lower (p < .05) during deep-water running than during treadmill running. During submaximal absolute work the heart rate was higher during deep-water running than during treadmill running for the elderly women. The participants had lower maximal oxygen uptake, heart rate, ventilation, respiratory-exchange ratio, and rate of perceived exertion during maximal deep-water running with a vest than during maximal treadmill running. These responses were, however, higher during submaximal deep-water running than during treadmill running.

Adipose tissue extracts plasma ammonia after sprint exercise in women and men.

This study evaluates a possible contribution of adipose tissue to the elimination of plasma ammonia (NH(3)) after high-intensity sprint exercise. In 14 healthy men and women, repeated blood samples for plasma NH(3) analyses were obtained from brachial artery and from a subcutaneous abdominal vein before and after three repeated 30-s cycle sprints separated by 20 min of recovery. Biopsies from subcutaneous abdominal adipose tissue were obtained and analyzed for glutamine and glutamate content. After exercise, both arterial and abdominal venous plasma NH(3) concentrations were lower in women than in men (P < 0.01 and P < 0.001, respectively). All postexercise measurements showed sex-independent positive arterio-subcutaneous abdominal venous plasma NH(3) concentration differences (a-v(abd)), indicating a net uptake of NH(3) from blood to adipose tissue. However, the fractional extraction (a-v(abd)/a) of NH(3) was higher in women than in men (P < 0.05). The glutamine-to-glutamate ratio in adipose tissue was increased after the second and third bout of sprint exercise (2.2 +/- 0.7 and 1.6 +/- 0.8, respectively) compared with the value at rest (1.2 +/- 0.6), suggesting a reaction of the extracted NH(3) with glutamate resulting in its conversion to glutamine. Adipose tissue may thus play an important physiological role in eliminating plasma NH(3) and thereby reducing the risk of NH(3) intoxication after high-intensity exercise.

Metabolismo miocárdico após cardioplegia sangüínea hipotérmica retrógrada contínua com inducão anterógrada normotérmica / Myocardial metabolism after hypothermic retrograde continuous blood cardioplegia with anterograde warm cardioplegic induction

OBJETIVO: Determinar as alteracões sofridas pelo miocárdio durante a cardioplegia sangüínea hipotérmica retrógrada contínua com a adicão da inducão cardioplégica anterógrada normotérmica. MÉTODO: Análise metabólica da cardioplegia sangüínea hipotérmica retrógrada contínua com inducão anterógrada normotérmica em estudo prospectivo de 15 pacientes consecutivos. Amostras de sangue arterial e do seio coronário foram simultaneamente colhidas para análise do conteúdo de oxigênio e da concentracão de lactato. Quatro biópsias miocárdicas foram obtidas para análise dos níveis de ATP, ADP, AMP e lactato no miocárdio. A isoenzima CK-MB foi analisada no sangue venoso. RESULTADOS: Não houve mortalidade no grupo. Nenhum paciente necessitou de suporte inotrópico na saída de CEC e não foi detectado IAM per ou pós-operatório. Ocorreu diminuicão da extracão artério-venosa do lactato e do oxigênio pelo coracão durante a reperfusão, havendo uma recuperacão parcial ao final de 60 minutos de reperfusão. Os níveis miocárdicos de ATP e de seus nucleotídeos foram mantidos durante o pincamento aórtico, porém houve reducão destes nos primeiros 30 minutos de reperfusão. O lactato acumulou-se no músculo cardíaco durante o pincamento aórtico, havendo reducão durante a reperfusão. CONCLUSÕES: Concluímos por uma análise metabólica que o método não conseguiu evitar o metabolismo anaeróbico durante o período de pincamento aórtico e que somente com 60 minutos de reperfusão foi observado um grau de recuperacão metabólica satisfatória. Provavelmente essas alteracões são devido à injúria isquêmica celular ocorrida durante o pincamento aórtico e parecem ter efeito transitório. Observamos melhora da protecão miocárdica com o acréscimo da inducão cardioplégica anterógrada normotérmica.

Golf: a high intensity interval activity for elderly men.

BACKGROUND AND AIMS: The aim was to quantify the time spent at different exercise intensities for male golfers, in relation to age, while walking a "normal" 18-hole golf course. METHODS: 19 healthy male golfers (six 27 (5) years old, seven of 50 (7) and six of 75 (4) years) performed a maximal exercise test on a treadmill (maximal oxygen uptake and maximal heart rate were measured). Within one week, they played an "average" 18-hole course starting at 7:00 a.m. During the round, their heart rate was monitored with a Polar Vantage heart rate monitor, which sampled the heart rate every 5 seconds. Body weight was measured before and after the round. Blood glucose was taken at rest before the round and after each 3rd hole. Perceived exertion and perceived pain in muscles and joints were rated using the CR 10 Borg scale just before reaching each green and after a few selected uphill parts of the course. RESULTS: High intensity of exercise was reached during 6% of the total playing time for the young, 30% for the middle-aged and 70% for the elderly golfers, playing 18 holes (p < 0.05). The golfers' heart rate was below 50% of their individual maximal heart rate, 18% of total time for young golfers, 16% for the middle-aged, and not at all for the elderly. Perceived exertion, breathlessness and leg fatigue were rated in a similar manner for all three groups. Perceived pain in joints and muscles was rated extremely weak except in a few players who had some known joint or muscle problem. The mean blood glucose level fell by 20% for the young (p < 0.05), 10% for the middle-aged, and 30% for the elderly players (p < 0.05) after 18 holes of play. Body weight was reduced 0.7% similarly for all three groups (p < 0.05). CONCLUSIONS: Walking an 18-hole golf course corresponds to an exercise intensity which is moderate and high for the elderly, mainly low to moderate for the middle-aged, and low for young male golfers. All golfers, regardless of age, perceived their exertion similarly as weak to moderate.

Water exchange induced by unilateral exercise in active and inactive skeletal muscles.

Water exchange was evaluated in active (E-leg) and inactive skeletal muscles by using (1)H-magnetic resonance imaging. Six healthy subjects performed one-legged plantar flexion exercise at low and high workloads. Magnetic resonance imaging measured calf cross-sectional area (CSA), transverse relaxation time (T2), and apparent diffusion capacity (ADC) at rest and during recovery. After high workload, inactive muscle decreased CSA and T2 by 2.1% (P < 0.05) and 3.1% (P < 0.05), respectively, and left ADC unchanged. E-leg simultaneously increased CSA, T2, and ADC by 4.2% (P < 0.001), 15.5% (P < 0.05), and 12.5% (P < 0.001), respectively. In conclusion, ADC and T2 correlated highly with muscle volume, indicative of extravascular water displacement closely related to muscle activity and perfusion, which was presumably a combined effect of increased intracellular osmoles and hydrostatic forces as driving forces. A distinguishable muscle temperature release was initially detected in the E-leg after high workload, and the ensuing recovery of ADC and T2 indicated delayed interstitial restitution than restitution of the intracellular compartment. Furthermore, absorption of extravascular water was detected in inactive muscles at contralateral high-intensity exercise.

Metabolismo miocárdico após cardioplegia sanguínea hipotérmica retrógrada contínua / Myocardial metabolism after hypothermic retrograde continuous blood cardioplegia

CASUISTICA E METODOS: Realizamos uma análise metabólica da cardioplegia sanguínea hipotérmica retrógrada contínua em um estudo prospectivo de 15 pacientes consecutivos encaminhados para operaçäo eletiva de revascularizaçäo miocárdica. Os critérios de inclusäo foram doença coronária bi ou triarterial e funçäo ventricular preservada (FE > 40 por cento). Os critérios de exclusäo foram angina instável, diabéticos insulino-dependentes e operaçöes associadas. Três pacientes foram excluídos do trabalho (operaçäo associada e deslocamento do cateter de cardioplegia retrógrada). Amostras de sangue arterial e do seio coronário foram simultaneamente colhidas: antes do início da CEC, na abertura da aorta e com 10, 30 e 60 minutos de reperfusäo, para análise do conteúdo de oxigênio e da concentraçäo de lactato. Quatro biópsias miocárdicas foram obtidas do ápice do ventrículo esquerdo: (1) após instalaçäo da CEC (mas antes do pinçamento aórtico), (2) imediatamente após o término da induçäo cardioplégica, (3) antes do despinçamento aórtico e (4) com 30 minutos de reperfusäo, para análise dos níveis de ATP, ADP, AMP e lactato no miocárdio. A isoenzima CK-MB foi analisada no sangue venoso. RESULTADOS: Näo houve mortalidade no grupo. Houve uma diminuiçäo da extraçäo artério-venosa do lactato e do oxigênio pelo coraçäo durante a reperfusäo, somente havendo uma recuperaçäo parcial ao final de 60 minutos de reperfusäo. O ATP e os outros nucleotídeos tiveram os seus níveis mantidos no miocárdio durante o pinçamento aórtico, mas estes caíram nos primeiros 30 minutos de reperfusäo. O lactato acumulou-se no músculo cardíaco durante o pinçamento aórtico e diminuiu durante a reperfusäo. Houve um aumento da enzima CK-MB, principalmente entre a terceira e sexta horas de pós-operatório. CONCLUSOES: Do ponto de vista metabólico, o método näo evitou o metabolismo anaeróbico durante o período de pinçamento aórtico e que somente com 60 minutos de reperfusäo houve uma recuperaçäo metabólica parcial. Essas alteraçöes säo, provavelmente, o reflexo da injúria isquêmica celular ocorrida durante o pinçamento aórtico e säo de efeito transitório