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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eight young men underwent an 8-month endurance exercise training program. Prior to and following the training program, the subjects' maximal oxygen uptake (VO2max), total blood volume (TBV) and plasma volume (PV), tolerance to lower body negative pressure (LBNP) assessed by the cumulative stress index (CSI) to presyncope, and their hemodynamic responses to 0 to -45 torr LBNP was determined. Hemodynamic measures included rebreathe carbon dioxide cardiac output (Qc), heart rate (HR), directly measured arterial blood pressures (ABP), and strain gauge determination of forearm blood flow (FBF) and leg volume changes (delta LgV). Calculated values of stroke volume (SV), forearm, vascular resistance (FVR), and peripheral vascular resistance (PVR) were made. Following training, each subject had an increased VO2max (mean = +27.4%, P < 0.001), TBV (mean = +15.8%, P < 0.02), and PV (mean = +16.5%, P < 0.02) and each subject had a decreased tolerance to LBNP (mean CSI = -24%, P < 0.001). Stepwise linear regression identified that the major factors to significantly predict the decreased CSI pre- to post-training were a reduced response of PVR to LBNP from -15 to -45 torr (Model R2 = 0.853), the delta TBV (model R2 = 0.981), and the greater post-training reduction in SBP to LBNP of 0 to -45 torr (model R2 = 1.0). These data suggest that physiologic adaptations associated with the increased VO2max and TBV resulting from a prolonged endurance exercise training program can alter the reflex control of vasomotion and cardiac output during LBNP and reduce the LBNP tolerance.
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PMID:Reduction in LBNP tolerance following prolonged endurance exercise training. 143 75

This study investigated the cardiorespiratory (CR) responses at rest and during submaximal (0-W) functional electrical stimulation (FES)-induced leg cycle ergometer (LCE) exercise prior to and following a progressive intensity FES-LCEa exercise training program in spinal cord injured (SCI) subjects. Seven quadriplegics and six paraplegics participated in FES-LCE training three sessions per week for approximately 12 weeks (36 sessions). Monitored CR responses, including oxygen uptake (VO2), pulmonary ventilation (VE), respiratory exchange ratio (RER), arteriovenous O2 difference (a-vO2), blood pressure (BP), heart rate (HR), stroke volume (SV), total peripheral resistance (TPR), and cardiac output (Q), were determined before and after training. Power output (PO) increased significantly (p < .05) over the duration of the training program, indicating increased in strength and endurance of the paralyzed muscles used. Respiratory responses were not significantly altered by training in both groups. FES-LCE training significantly increased resting HR and SBP in quadriplegics and lowered SBP, DBP, and MAP in paraplegics. In both groups, HR and BP during submaximal exercise significantly decreased and SV and Q significantly increased after completion of the training program. These results suggest that FES-LCE training improves peripheral muscular and central cardiovascular fitness in SCI subjects. Posttraining HR and BP may also be more stable in quadriplegics and alleviate hypotension. This therapeutic exercise may ultimately lead to improved rehabilitation outcome and reduced stress during activities of daily living, and possibly reduce the risks for secondary CR disabilities.
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PMID:Functional electrical stimulation leg cycle ergometer exercise: training effects on cardiorespiratory responses of spinal cord injured subjects at rest and during submaximal exercise. 144 77

Every 4 hours for 24 hours, 14 clinically healthy young individuals (6 women and 8 men), 26 +/- 4 years of age, measured systolic (S) and diastolic (D) blood pressure (BP) by sphygmomanometer and heart rate by ECG and did impedance cardiography under usual living conditions. Stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were calculated. Time series of SBP, DBP, HR, SV, CO and TPR were analyzed by single and population-mean cosinor. A circadian cardiovascular rhythm is demonstrated by rejection of the zero amplitude assumption in the population-mean cosinor test for SBP, DBP, HR, SV, CO and TPR (P < 0.01). TPR peaks around 0400 (-61 degrees from local midnight), in antiphase with all other variables, their acrophase occurring around 1600 (-240 degrees). A circadian rhythm of statistical significance or of borderline statistical significance is found for all variables except TPR in women. Circadian rhythm characteristics were otherwise mostly similar in men and women with a statistically significant gender difference found by parameter tests only for the MESOR and amplitude of SBP.
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PMID:Circadian relations among cardiovascular variables of young adults. 147 12

To examine the effect of acute hyperbaric exposure on cardiovascular response to orthostasis, a passive 70 degrees head-up tilt (HUT) test was performed for 15 min in a simulated compressed-air hyperbaric environment of 3 atm abs at ambient temperature of 31 degrees C (thermoneutral) on 8 male subjects. Heart rate (HR), blood pressure, cardiac output (CO) by impedance cardiography, forearm blood flow (FBF) by the occlusion plethysmography, and laser-Doppler skin blood flow (BFLD) on the thigh were measured for 15 min before, during, and after HUT. Esophageal temperature and HR data were recorded continuously. An identical test was performed in a 29 degrees C (thermoneutral) normal atmospheric condition. None of the subjects showed signs of syncope during HUT in either environment. Baseline HR was significantly lower (P less than 0.05) at 3 atm abs, and the increase in HR (delta HR) during HUT was of the same magnitude (15 beats/min) at both atmospheric pressures. The reduction of systolic blood pressure (delta SBP) was identical in both environments. Thus, the chronotropic response to HUT (delta HR/delta SBP) was the same. A marked reduction in CO (P less than 0.05) was attributed to a reduction of stroke volume during HUT, and the reduction was greater (P less than 0.05) at 3 atm abs. There were no pressure-dependent changes during HUT in FBF, forearm vascular resistance, and BFLD except for a greater increase (P less than 0.05) in total peripheral resistance at 3 atm abs. These observations suggest that orthostatic tolerance was maintained in the presence of lower CO at 3 atm abs, probably by a greater vasoconstrictor response in the splanchnic areas. We conclude that the substantial bradycardia which occurred at 3 atm abs did not interfere with a normal response to orthostasis in humans because of a peripheral vasoconstriction caused by the elevated oxygen pressure and an enhanced increase in total peripheral resistance which occurred during HUT in 3 atm abs.
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PMID:Cardiovascular responses to upright tilt in man during acute exposure to 3 atm abs air. 156 23

We report the results of a multicenter study performed on 70 patients with severe congestive heart failure of different etiology (ischemic, idiopathic, alcoholic, valvular and secondary to antiblastic drugs) to evaluate the clinical and hemodynamic effects and tolerability of low dose amrinone iv (0.75 mg bolus followed by a continuous 48-hour infusion at the dose of 5-10 mcg/kg/min). Forty-one patients underwent invasive hemodynamic monitoring with right heart Swan-Ganz catheterization. Heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), cardiac index (CI), stroke volume index (SVI), stroke work index (SWI), right atrial pressure (RAP), pulmonary wedge pressure (PWP), mean arterial pulmonary pressure (PAP), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR) and total pulmonary resistance (TPR) were evaluated before and after 1, 4, 6, 24 and 48 hours of amrinone infusion and 2 and 4 hours after amrinone withdrawal. Clinical parameters (dyspnea, orthopnea, pulmonary congestion) were quantitated using a score; diuresis was assessed hourly; hematochemical parameters were evaluated before and 48 hours after amrinone infusion. HR and MAP were not significantly changed; CI, SVI and SWI presented, respectively, a significant 31.6, 55.1 and 72% increment, which peaked 48 hours after amrinone infusion. Concomitantly RAP, PAP, PWP, SVR, PVR and TPR were significantly reduced to 36.6, 22, 23.6, 9.4, 39.2 and 37.7% of the basal values, respectively. Two and 4 hours after amrinone withdrawal, hemodynamic changes similar to those observed acutely, were still present. Diuresis increased from 58.25 ml/hr to 113.18 ml/hr after 24 hours (+95%) and to 88.9 ml/hr (+53%) after 48 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Hemodynamic and clinical effects and treatment tolerance with low-dose iv amrinone in patients with refractory heart failure: a multicenter study. The Group for Research on Amrinone in the Treatment of Refractory Heart Failure]. 175 41

ISH is a distinct pathogenetic entity defined by SBP readings of greater than or equal to 160 and DBP less than 90 mmHg. The etiology, although not well understood, is in some manner related to a reduction in connective tissue elasticity of large blood vessels and an increase in aortic impedance or a decrease in aortic wall compliance. The pathophysiologic consequences include an increased resistance to systolic ejection of blood and a disproportionate increase in SBP. Although not directly related, there is an important increase in peripheral vascular resistance. The prevalence of ISH in several studies is about 7 percent in those over age 60 and increases with age to nearly 20 percent in those over age 80. There is higher prevalence in females and nonwhites. The guidelines for detection of ISH are similar to those for blood pressure evaluation in general. Precautions for detection and evaluation in the elderly include multiple blood pressure measurements in the fasting state and sitting and supine blood pressure measurements before and during therapy. Pseudohypertension, although rare, should be kept in mind. There is a clear risk associated with ISH for stroke, CVD, and premature death, which increases with age and rising levels of SBP. ISH can be controlled effectively with pharmacologic therapies. A reasonable goal is a 20 mmHg reduction in systolic pressure. Proof of reduced risk for stroke, CHD, and death in those with controlled ISH remains to be demonstrated. The SHEP pilot study has demonstrated feasibility of addressing this issue. The full-scale SHEP study addresses this issue and has completed recruitment of the desired sample size and is in follow-up phase. Scheduled completion is in 1991. While we wait for the SHEP full-scale trial results, the prudent approach is for nonpharmacologic therapy and use of pharmacologic agents in that group of patients who demonstrate a large cardiovascular risk burden or increasing symptoms specifically associated with hypertension. The decision to treat must be on an individual patient basis. Pharmacologic therapy is possible in most patients with few or no adverse effects. The "low and slow" approach to therapy is helpful in minimizing these adverse effects. Low-dose diuretics have been documented to be effective in blood pressure control. Chlorthalidone, 12.5 or 25 mg per day, is suggested. Other agents, such as beta-blockers, reserpine, ACE inhibitors, and calcium channel blockers, are best used as Step 2 agents.
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PMID:Systolic hypertension in the elderly: controlled or uncontrolled. 218 67

The effects of acute volume and/or pressure loading on myocardial metabolic and mechanical function were studied in 13 dogs. Volume loads were applied by shunting the abdominal aorta to the vena cava using polyethylene tubing (5 mm inner diameter). A plastic regulator allowed shunts to be opened or closed. Dogs were heparinized (100 units/kg) to prevent shunts from clotting. To study the effects of pressure loading, a norepinephrine infusion (1 microgram/kg/min) was administered. Mechanical function of the heart was evaluated using heart rate X systolic blood pressure (HR X SBP), cardiac output (CO), pressure X volume work (systolic blood pressure X stroke volume); (P X V), and oxygen consumption (MVO2) to estimate external myocardial work. Metabolic function was evaluated by 31P NMR. Phosphocreatine/adenosine triphosphate (PCr/ATP) ratios were used to estimate the bioenergetic regulation of oxidative phosphorylation during increased work load. HR X SBP, CO, P X V, and MVO2 were correlated with PCr/ATP. Although there was some variability, generally volume loading was associated with an increase in HR X SBP, CO, P X V, and MVO2 accompanied by no change, or small increases or small decreases in PCr/ATP throughout the loading period. These data indicate that the heart bioenergetics are quite stable during volume and/or pressure loading and that 31P spectroscopy methods can document this stability and tight metabolic regulation during in vivo loading conditions.
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PMID:In vivo myocardial bioenergetics during acute volume and/or pressure loading in a canine model: a 31P NMR study. 261 95

Whilst recruiting for the Randomised Trial of the Treatment of Hypertension in Elderly Patients in Primary Care, 10,732 people aged 60-79 years of age (4,736 males and 5,996 females) were screened for hypertension. This constituted 78% of those eligible on the practice lists in this age range. These patients were followed up for a mean period of 2.6 years (range 0.1-11.2 years). All those leaving the practices were registered with the National Health Service Central Registry to ensure completeness of death ascertainment. 1,009 deaths were analysed and standardised mortality ratios computed for all deaths, stroke, coronary artery disease and all cardiovascular causes. Hypertensive patients included in the control group of the trial were also matched with patients found to be normotensive and their mortalities compared. Both high and low levels of SBP were associated with increased mortality producing a U-shaped curve for all deaths and J-shaped curves for cardiovascular causes. With increasing age the higher mortality associated with lower SBP became more pronounced. Similar effects were evident for DBP but in women high DBP was less dangerous than in men. Although the relative impact of hypertension declines with advancing age, the absolute impact is maintained up to the age of eighty.
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PMID:The prognostic significance of blood pressure in the elderly. 324 49

The effect of induction of epidural analgesia with 0.5 per cent bupivacaine on maternal haemodynamics was investigated in 21 patients with uncomplicated full-term pregnancies in early labour. Stroke volume, heart rate, and cardiac output (SV, HR, and CO) were measured by transcutaneous aortovelography (TAV). Systolic, diastolic, and mean arterial blood pressures (SBP, DNP, and MAP) were measured by indirect automatic oscillometry. Measurements were made with the patient in the left lateral decubitus position before and after an intravenous bolus of 500 ml of lactated Ringer's solution preceding induction of epidural analgesia, and again 30 and 45 minutes after induction. The 500 ml bolus of lactated Ringer's solution did not prevent fall of CO and BP measured 30 minutes after induction, when there were statistically significant decreases in CO and cardiac index (-10.2 and -10.6 per cent, p less than 0.05), and in SBP, DBP, and MAP (-9.7, -12.5, and -11.9 per cent, p less than 0.005, p less than 0.005 and p less than 0.01 respectively). At 45 minutes after induction, CO and cardiac index had returned to baseline values. Although the decreases in SDP and DBP persisted, the change in MAP was not statistically significant.
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PMID:Haemodynamic effects of induction of epidural analgesia in labour. 334 53

Effects of 1-[(S)-3-acetylthio-2-methylpropanoyl]-L-prolyl-L-phenylalanine (alacepril, DU-1219) a new orally active angiotensin converting enzyme (ACE) inhibitor, on cardiovascular system in experimental animals were examined. In conscious renal hypertensive dogs, alacepril (3 mg/kg p.o.) caused a marked reduction in systolic and diastolic blood pressure (SBP and DBP) and total peripheral vascular resistance (TPR), but did not change significantly heart rate (HR), cardiac output (CO), stroke volume (SV), cardiac work (CW) and electrocardiogram (ECG). Captopril (3 mg/kg, p.o.) showed similar changes in cardiovascular parameters as alacepril. In anesthetized open-chest normotensive dogs, alacepril (3-100 micrograms/kg/min for 10 min, i.v. infusion) tended to decrease DBP and TPR, but did not change significantly CO, stroke work (SW), left ventricular end diastolic pressure (LVEDP), dp/dt and HR. Captopril also showed similar effects but these changes were greater in extent than those of alacepril. In conscious renal hypertensive rats, alacepril did not affect the regional cerebral blood flow in the frontal cortex and the dorsal hippocampus after single (3 and 10 mg/kg) and successive (3 mg/kg/d for 7 days) oral administration. Captopril (10 mg/kg) significantly decreased blood flow in the frontal cortex after single oral administration. In conscious normotensive dogs, alacepril (3 and 30 mg/kg p.o.) increased renal plasma flow (RPF), urine volume (UV), urinary sodium excretion (UNaV) and urinary Na+/k+ ratio, but did not change glomerular filtration rate (GFR) and urinary potassium excretion (UKV). Captopril (3 and 30 mg/kg p.o.) also showed similar changes as alacepril. These effects of alacepril on cardiovascular system resemble those of captopril and might be considered as a favourable profile for the antihypertensive agent.
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PMID:Effect of the novel orally active angiotensin converting enzyme inhibitor alacepril on cardiovascular system in experimental animals. 351 79


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