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At least 19 recordsLinked to original sources
PubMed2026

Modulation of heart rate and heart rate variability during animal-assisted treatment of patients in a minimally conscious state: A randomized controlled crossover study.

BACKGROUND: Animal-assisted treatment (AATx) is a promising and increasingly used approach in neurorehabilitation, yet its psychophysiological effects remain largely unexplored. Patients in a minimally conscious state (MCS) show severely altered consciousness with minimal but definite behavioral signs of awareness. Because behavioral assessment in this population is limited, psychophysiological measures such as heart rate (HR) and heart rate variability (HRV) may offer valuable insights into autonomic regulation during therapy. AIM: The present study investigated whether AATx influences HR and HRV compared to treatment as usual (TAU). METHODS: A randomized controlled crossover design with repeated measures was conducted. HR and HRV data were recorded using an Empatica E4 wristband, and linear mixed-effects models were fitted for each outcome variable. The analytic sample included twenty-one patients with MCS who completed at least one of the four sessions. RESULTS: We found a significant decrease in mean HR (estimate = -12.75, p = .041) and a significant increase in the standard deviation of normal-to-normal intervals (SDNN) (estimate = 15.76, p = .020) during AATx compared to TAU from the pretreatment to the posttreatment phase, indicating enhanced parasympathetic activation and greater autonomic flexibility. Other HRV parameters revealed no significant effects of AATx, though trends were consistent with the hypotheses. CONCLUSIONS: These findings provide preliminary physiological evidence that AATx can modulate autonomic activity in MCS patients. Despite limitations related to sample size and recording quality, the results highlight the potential of AATx as an emotionally engaging intervention in early neurorehabilitation.

Humans↗
PubMed1975

[Effect of ambient temperature on metabolism and heart rate of resting albino rats].

Heart rate and oxygen consumption were measured simultaneously in albino rats. These measurements were carried out in the resting animal at different temperatures between 18 degrees and 33 degrees C. The metabolism evolution with the environmental temperature allowed to place the thermal neutrality at 29 degrees C. The resting heart rate varies as metabolism. It shows the lowest values round the thermoneutrality and increases quickly as the environment is cooling. This result shows the effect of the thermal environment upon the resting heart rate level. On the other hand, the non linear relationship between metabolism and heart rate points out that the heart rate increase is not the only factor that allows an increased oxygen consumption during the body temperature regulation.

Animals↗
PubMed1975

The effect of sulfhydryl reagents on the heart rate and coronary flow of the isolated perfused guinea-pig heart.

The action of a number of compounds able to react with thiols was tested on guinea-pig hearts perfused at constant pressure. The SH reagents used were NaNO2, oxidized glutathione, cystamine, diamide, 1,5-difluoro-2,4-dinitrobenzene, nitroglycerol, sodium nitroferricyanide and HgCl2. 6,6'-Dithiodinicotinic acid, an SH reagent that does not penetrate the cell, produced no effect. All the other SH reagents produced an increase in coronary flow. All except oxidized glutathione and nitroglycerol increased the heart rate. The increase in heart rate and oxygen consumption could be completely blocked by dichloroisoproterenol; the increase in coronary flow was not affected. Difluorodinitrobenzene, diamide, cystamine and NaNO2 significantly decreased the acid-soluble thiol content of the heart. For these compounds, there was a significant correlation between the decrease in coronary flow and the decrease in thiols. We conclude that in the isolated heart, most SH reagents, if used at the appropriate concentration, will increase the heart rate, probably by relaasing catecholamines. They will also decrease the coronary resistance, probably by a direct effect on the coronary vessels.

Animals↗
PubMed1976

Detection of cyclic sleep phenomena using instantaneous heart rate.

The development of the Heart Beat Domain and the Fourier transform of the Heart Beat Domain (which we call the Beatquency Domain) has provided new and useful tools for the quantitative analysis of sleep level patterns. This method of analysis has produced remarkable intersubject as well as intra-subject consistency and the only physiologic parameter required in the analysis is beat-by-beat heart rate. This analytical tool was designed to aid in the detection of sleep cycles, or more specifically, the rhythmic transitions from REM+ (awake Stages 1 and REM combined) to NREM (Stage 2, 3 and 4 combined) over a normal night of sleep. Employing this method on minute-by minute sleep recordings from 9 normal sleep subjects, 2 complete nights each, we were able to distinguish between the REM+ and NREM stages with an average accuracy of approximately 80%. Considering that beat-by-beat heart rate was our only criteria, we felt that the algorithm performed with significant success.

Heart Rate↗
PubMed1979

Cardiac performance: optimal heart rate for maximal cardiac output.

To determine optimal heart rate for the maximal cardiac output at various levels of inotropy and blood volume, the relationship between heart rate (HR) and stroke volume (SV) was examined in anaesthetized dogs during right atrial pacing. Myocardial inotropy was raised by intravenous infusion of isoproterenol, a stimulator of adrenergic beta-receptors, and reduced by propranolol, an inhibitor of adrenergic beta-receptors. Circulating blood volume was increased by saline infusion. Within the range of optimal heart rate, SV and HR were inversely related: SV = k (HR0-HR), where k indicates the relationship between changes in SV and HR. The intercept with the HR axis is HR0. At constant HR a rise in inotropy increased SV and a fall in inotropy reduced SV. These changes in SV were eual at every HR, and k was therefore constant. In contrast, blood volume expansion increased SV more at low than at high HR (k increased), but HR0 was not significantly changed. Calculated maximal cardiac output: k.HR02/4, and optimal heart/rate: HR0/2, agreed with observations when maximal cardiac output was raised from 1900 to 4500 ml/min by increasing blood volume and inotropy. Optimal HR was not influenced by changes in blood volume, but was increased from 160 to 200 beats/min by increasing inotropy. We conclude that the optimal heart rate and the maximal cardiac output can be predicted from the linear relationship between SV and HR during right atrial pacing.

Adrenergic beta-Agonists↗
PubMed1976

Effect of beta-adrenoreceptor blockers on heart rate and blood pressure in dynamic and isometric exercise.

Previous studies on the effects on heart rate and blood pressure in normals and hypertensive patients during dynamic exercise (ergometer bicycling or treadmill walking) and isometric exercise (sustained handgrip) are reviewed. In one study utilising sub-maximal bicycle exercise in hypertensives, there was a 43% increase in heart rate for a 33% increase in systolic pressure and 5% fall in diastolic pressure. Beta-adrenoreceptor blockade decreased the heart rate level by 18 to 19% for a decrease of systolic blood pressure level by 4 to 11%, whereas the diastolic pressure level was unaffected. A protocol is described utilising a blind indirect blood pressure recording machine ("Auto-Manometer") with which cuff inflation and deflation are automatic and constant, and blood pressure values stored at suitable Korotkov sound phases. The machine also records heart rate. By this method, isometric exercise at 50% of maximal voluntary contraction (sustained handgrip) has been studied in normals and hypertensives off and on different treatments. Both in normals and established hypertensives, there was about a 25% increase in systolic blood pressure during isometric exercise for about a 22% increase in diastolic blood pressure, and 26% increase in heart rate. Normotensive women had the lowest rise in blood pressure and the highest rise in heart rate. Beta-Adrenoreceptor blocking agents lowered heart rate during isometric exercise by 15 to 20% but did not affect the blood pressure level. Since resting blood pressure levels were decreased, the percentage rise in pressure was enhanced following beta-blockers. A combination of a beta-blocker, clonidine and/or a vasodilator produced a reduction in both systolic (24%) and diastolic (12%) pressure, as well as in heart rate (18%), during isometric exercise.

Adrenergic beta-Antagonists↗
PubMed1977

Halothane depresses baroreflex control of heart rate in man.

Baroreflex control of heart rate was determined during three awake control situations and during two depths of halothane anesthesia in man. Baroreflex function was quantiated by calculating the pressor test slope from the R-R interval change on the ECG produced by a pharmacologically induced pressor response. During the three awake control situations the subjects breathed room air or 100 per cent O2 spontaneously or 100 per cent O2 with ventilation controlled. Mean (+/- SD) slopes obtained were 15.1 +/- 4.5, 15.6 +/- 6.8 and 18.4 +/- 9.9, respectively. No significant difference in baroreflex function slope was observed. During light halothane anesthesia (0.7 per cent endtidal) baroreflex function was significantly depressed (mean slope = 2.5 +/- 1.5), and it was abolished at 1.1 per cent end-tidal halothane (mean slope = 0.03 +/- 0.04). It is concluded that halothane anesthesia produces depression of baroreflex control of heart rate in man.

Adult↗
PubMedDate not supplied

Acquisition and discrimination of appetitively and aversively conditioned heart rate responses in rhesus monkeys.

This report describes the acquisition of a conditional heart rate response to both classical aversive and appetitive conditioning in eight rhesus monkeys (Macaca mulatta). The behavioral paradigm consisted of two discrete one minute tones followed by the corresponding unconditional stimuli, i.e., electric shock or Purina monkey chow. A third tone followed by neither food nor shock served as a discriminative stimulus (DS). The conditional heart rate responses developed in two phases. The first phase was characterized by similar responses to both conditional stimuli and the DS. Control heart rate rose during this period. During the second phase, control heart rate decreased (five animals), the DS response disappeared, and different conditional heart rate patterns to food and shock emerged. The existence of distinct conditional response patterns indicates probable differences in the autonomic nervous regulation of the heart during aversive and appetitive conditioning.

Animals↗
PubMed1979

Inefficacy of digitalis in the control of heart rate in patients with chronic atrial fibrillation: beneficial effect of an added beta adrenergic blocking agent.

The role of digoxin and the new beta adrenergic blocking agent, timolol, in controlling heart rate at rest and during exercise was investigated in 28 patients with chronic atrial fibrillation. Digoxin failed to prevent excessively rapid heart rates during mild to moderate exercise. Increasing digoxin blood levels from a mean of 0.6 to 1.8 ng/ml had no effect on heart rate either at rest or during exercise. The addition of timolol, 20 to 30 mg/day, resulted in a satisfactory and significant attenuation of the rapid heart rates both at rest and during exercise. Heart rates at rest were 91 and 98 beats/min in the patients with low and high digoxin dosage and rose to 135 and 139 beats/min, respectively, during exercise. Timolol reduced the heart rate to 67 at rest and to 92 beats/min during exercise. The effect of beta adrenergic blockade at rest was less pronounced in patients whose initial heart rates were below 90 beats/min. Digoxin alone may not suffice to control excessive heart rate in patients with chronic atrial fibrillation. The additional beta adrenergic blockade actually normalizes the heart rate response in these patients.

Adrenergic beta-Antagonists↗
PubMed1978

Sympathetic and parasympathetic control of heart rate in unanaesthetized fetal and newborn lambs.

Development of autonomic nervous control of basal heart rate was studied in unanesthetized fetal lambs (93 days to term) and newborn lambs (2--29 days), using atropine and/or propranolol blockade. Fetal lambs showed a progressive increase in parasympathetic restraint of heart rate; vagal influence in the newborn lamb was similar to the term fetus. Sympathetic stimulation of fetal heart rate declined toward term, possibly due to the strongly increasing parasympathetic influence. Sympathetic influence in the newborn was similar to the early-gestation fetus. Intrinsic heart rate was about 185 beats/min throughout the fetal and newborn life span studied. Thus changes in basal heart rate resulted from a different balance of the sympathetic and parasympathetic components of the autonomic nervous outflow.

Adrenergic beta-Antagonists↗
PubMed1979

A scoring system for nonstressed antepartum fetal heart rate monitoring.

A scoring system developed to assess nonstressed antepartum fetal heart rate records has been evaluated. The system scores from 0 to 2 for each of five factors, i.e., baseline rate, amplitude and frequency of fluctuation, decelerations, and accelerations. A total of 1,367 nonstress tests in 284 patients were retrospectively reviewed. Three groups of patients were delineated with respect to the fetal heart rate scores. When the group with the highest score of 8 to 10 and a perinatal mortality rate (PNM) rate of 4.7/1,000 was compared with the groups having intermediate (5 to 7) and low (less than or equal to 4) scores, there was a highly significant increase in PNM to 69.8/1,000 (p less than 0.01) and 433/1,000 (p less than 0.001), respectively. A significant increase in low Apgar scores at 1 and 5 minutes, in fetal acidosis (low umbilical arterial pH), and in duration of intensive care nursery stay was also seen as the fetal heart rate score progressively deteriorated from the 8 to 10 group to the less than or equal to 4 group. We conclude that this scoring system clearly delineates normal from prepathologic and pathologic changes in fetal heart rate and can be used as warning of impending fetal death.

Apgar Score↗
PubMed1978

Heart-rates of surgeons during operations and other clinical activities and their modification by oxprenolol.

The heart-rates of surgeons were recorded by ambulatory monitoring methods while they operated and while they conducted surgical outpatient clinics. Heart-rates during operations were also monitored 1 hour after the surgeons had taken an oral dose of 40 mg oxprenolol. During operations the mean heart-rate of 8 surgeons was 121/min with maximum rates in some cases of over 150/min. The tachycardia was abolished by 40 mg of oxprenolol which reduced heart-rates during operations to below those recorded during surgical outpatient clinics. Physical work necessary to reproduce the mean heart-rate whilst operating could not be sustained for more than 10--15 min.

Depression, Chemical↗
PubMed2026

Reliability of resting heart rate measurements in atrial fibrillation.

BACKGROUND: Heart rate (HR) control in atrial fibrillation (AF) is commonly guided by resting HR measurements, usually with 12&#x2011;lead ECG or in-office pulse palpation. OBJECTIVES: We aimed to assess the reliability of resting HR measurements in AF patients with long-term ambulatory ECG and activity monitoring. METHODS: We included patients who had recorded a full-disclosure ambulatory ECG with a mobile cardiac telemetry device equipped with an accelerometer (PocketECG, MEDICALgorithmics, Poland), with at least 95% AF. Resting HR samples (&#x2264;20 per individual/day) were collected as 10-s daytime (8&#xa0;am to 8&#xa0;pm) measurements after &#x2265;10&#xa0;min of rest. These samples were compared to each individual's mean daytime resting HR. RESULTS: In 832 patients (median age 77 (interquartile range (IQR) 69-83) years, 42% women) with a median registration duration of 13&#xa0;days (IQR 7-22), the population mean daytime resting HR was 85 (&#xb1;15) beats per minute (bpm). A single resting HR differed from the mean daytime resting HR by a mean of &#xb1;10.4% (IQR 3.6-14.4%). When the mean daytime resting HR was &#x2265;110&#xa0;bpm, 29% of resting HR samples were&#xa0;<&#xa0;110&#xa0;bpm, and when the mean daytime resting HR was 80-109&#xa0;bpm,11% of samples were&#xa0;&#x2265;&#xa0;110&#xa0;bpm. Resting HR measurement variability decreased to 5.3% (IQR 1.9-7.5%) when four resting HR samples were averaged. CONCLUSION: In patients with AF, a single resting HR measurement often differs substantially from the mean daytime resting HR. When a precise measurement is clinically relevant, repeated resting HR sampling or ambulatory monitoring can address this measurement imprecision.

Humans↗
PubMed1976

Feedback of true heart rate during exposure in vivo. Partial replication with methodological improvement.

Ten specific phobics improved during a mean of two sessions of experimental treatment by exposure in vivo in a balanced design. Short-term results replicated those of a previous study that self-control of heart rate with the aid of biofeedback significantly reduced heart rate during treatment, but this did not hasten reduction of subjective anxiety, nor of respiratory rate or skin conductance responses. An hour's pretreatment training in self-control of heart rate with the aid of feedback did not enhance the effect. Mere instructions to lower heart rate without feedback had a significant effect during treatment, but the addition of heart rate feedback to instructions significantly augmented the decline in heart rate.

Adolescent↗
PubMed1976

Fetal heart rate and fetal movements.

Fetal Heart Rate (F.H.R.) in association with fetal movement was evaluated in 141 normal and pathological pregnancies. In the normal cases only 31% showed an acceleration of F.H.R. in association with fetal movement. The majority of the normal cases, 62%, did not demonstrate changes in F.H.R. in association with fetal movement. In the pathological pregnancies there were no characteristic changes in F.H.R. associated with fetal movement. It appears that F.H.R. acceleration associated with fetal movement cannot be used as an index for fetal well being.

Female↗
PubMed1977

[Fetal heart rate, dip area and acid base observations in breech and vertex deliveries (author's transl)].

Fetal heart rate (FHR), dip area (DA) and the acid base status (AB) were investigated in breech deliveries (BD) (N= 167) and in group of spontaneously delivered vertex presentations (VP) (NFHR, DA=50; NAB=109). 90 minutes prior to delivery fetal heart rate and dip area were in both groups not significantly different. However as labor progressed the fetal heart rate as well as dip area increased in breech deliveries much more (FHR 163 (SD 16.2) beats/min, DA 1,07 (SD 0,80) cm2/min) than in VP (FHR 136 (SD 14,8) beats/min, DA 0,65 (SD 0,39) cm2/min) (2p less than 0,001). The base excess of the umbilical arterial blood was correlated to the DA measured from 10 minutes prior to birth till the delivery of the baby: BE = -8,2 --0,3 (DA) (2alpha less than 0,01). The frequency of acidotic babies was more in vaginally delivered breech presentations (pH less than 7,20 = 30, 2%, BE greater than -10 meq/l = 43,7%) than in breech deliveries by caesarean section (pH less than 7,20 = 19,1%, BE greater than -10 meq/l = 24,4%) and vertex presentations (pH less than 7,20 - 5,5%, BE greater than -10 meq/l = 14,6%), respectively. The distance between the vertex and the umbilicus was 28 cm and between the breech and the umbilicus 9,4 cm. From this anatomical observation it is concluded that umbilical cord compression, preferentially umbilicai vein occlusion takes place in breech presentation at an earlier point on than in vertex presentation. The rise of fetal heart rate and the increase in dip area are showing in addition that the fetal buffer base in breech presentation will be reduced during the last time course of the second stage of labor.

Acid-Base Equilibrium↗
PubMed1978

Sinusoidal fetal heart rate pattern following intrauterine fetal transfusion.

Two patients with severe rhesus isoimmunization had sinusoidal fetal heart rate patterns following intrauterine fetal transfusion. A consistent temporal relationship between fetal transfusion and sinusoidal fetal heart rate pattern was observed. Survival of a fetus who had a sinusoidal fetal heart rate pattern after each of three transfusions suggests that this pattern may not be ominous when observed transiently after fetal transfusion.

Adult↗