Greater Decrease In Heart Rate Research Articles

Assessing the usability of aromatic mouthwashes in alleviating physiological stress responses.

Mouthwashes play a pivotal role in oral care, and their efficacy has been explored extensively across various dimensions. As a contribution to the development of novel oral care products, this study aims to investigate the psychophysiological effects of aromatic mouthwashes during the resilience period from a short-term cognitive stressor utilizing biological signals and subjective evaluations. A within-participant experimental design with 22 healthy females was conducted with four mouthwashes; peppermint (Mint), peppermint + bergamot (MB), peppermint + sweet orange (MO), and peppermint + lavender (ML), and water as the control (Ctl), after a 20-min calculation task. Subjective evaluations and physiological responses including skin conductance level and electrocardiogram were recorded throughout the experiment. Citrus mouthwashes (MO and MB) showed a greater decrease in heart rate and a significant increase in the high-frequency component of heart rate variability. The participants indicated a significant effect in terms of "flavor preference" and "refreshing sensation" for mouthwash use compared to the Ctl. The results suggest that rinsing with citrus-flavored mouthwashes has a positive impact in alleviating the physiological stress response (in terms of cardiac activity). These findings may have implications for the development of innovative, novel oral care products that promote stress reduction and improve oral health.

Hypertension in Primary Aldosteronism Is Initiated by Salt-Induced Increases in Vascular Resistance With Reductions in Cardiac Output.

Few studies have investigated the hemodynamic mechanism whereby primary aldosteronism causes hypertension. The traditional view holds that hyperaldosteronism initiates hypertension by amplifying salt-dependent increases in cardiac output (CO) by promoting increases in sodium retention and blood volume. Systemic vascular resistance (SVR) is said to increase only as a secondary consequence of the increased CO and blood pressure. However, mounting evidence indicates that aldosterone can influence multiple pathways regulating vascular tone. We investigated the primary hemodynamic mechanism whereby hyperaldosteronism promotes salt sensitivity and initiation of salt-dependent hypertension. In unilaterally nephrectomized male Sprague-Dawley rats given infusions of aldosterone or vehicle, we used chronically implanted arterial pressure probes and Doppler ultrasonic flow probes to continuously monitor changes in mean arterial pressure, CO, and SVR 24 hours/day, 7 days/week in response to increases in salt intake. In vehicle-treated control rats, switching from a low-salt diet to a high-salt diet initiated modest increases in mean arterial pressure by increasing SVR while simultaneously decreasing heart rate and CO. In aldosterone-treated rats compared with control rats, switching from a low-salt diet to a high-salt diet initiated significantly greater increases in mean arterial pressure and SVR and significantly greater decreases in heart rate and CO. Aldosterone promoted salt sensitivity and initiation of salt-dependent hypertension by amplifying salt-induced increases in SVR while decreasing CO. Increases in CO are not required for the initiation or maintenance of hypertension. These findings challenge the traditional view of the hemodynamic mechanisms that cause hypertension in primary aldosteronism.

Hypoglycaemia combined with mild hypokalaemia reduces the heart rate and causes abnormal pacemaker activity in a computational model of a human sinoatrial cell.

Low blood glucose, hypoglycaemia, has been implicated as a possible contributing factor to sudden cardiac death (SCD) in people with diabetes but it is challenging to investigate in clinical studies. We hypothesized the effects of hypoglycaemia on the sinoatrial node (SAN) in the heart to be a candidate mechanism and adapted a computational model of the human SAN action potential developed by Fabbri et al., to investigate the effects of hypoglycaemia on the pacemaker rate. Using Latin hypercube sampling, we combined the effects of low glucose (LG) on the human ether-a-go-go-related gene channel with reduced blood potassium, hypokalaemia, and added sympathetic and parasympathetic stimulus. We showed that hypoglycaemia on its own causes a small decrease in heart rate but there was also a marked decrease in heart rate when combined with hypokalaemia. The effect of the sympathetic stimulus was diminished, causing a smaller increase in heart rate, with LG and hypokalaemia compared to normoglycaemia. By contrast, the effect of the parasympathetic stimulus was enhanced, causing a greater decrease in heart rate. We therefore demonstrate a potential mechanistic explanation for hypoglycaemia-induced bradycardia and show that sinus arrest is a plausible mechanism for SCD in people with diabetes.

Effects of supervised exercise therapy on blood pressure and heart rate during exercise, and associations with improved walking performance in peripheral artery disease: Results of a randomized clinical trial

ObjectiveSupervised exercise therapy (SET) improves walking ability in people with peripheral artery disease (PAD). However, the effects of SET on cardiovascular health in PAD remain unclear. Using data from a randomized clinical trial, this post hoc analyses investigated the effects of a 6-month SET intervention, compared with a control group, on changes in blood pressure (BP) and heart rate (HR) during a graded treadmill exercise test in people with PAD. MethodsWe randomized 210 participants with PAD to either SET (3× weekly) or control (1× weekly health lectures) for 6 months. A graded treadmill exercise test, 6-minute walk test, and Walking Impairment Questionnaire were completed at baseline and the 6-month follow-up. BP and HR were measured at the end of each 2-minute stage of the graded treadmill exercise test. Mixed effects regression models compared the overall mean 6-month change in systolic BP, diastolic BP, pulse pressure (PP), and HR during the first 5 stages of the graded treadmill exercise test between groups. ResultsOf the 210 randomized participants with PAD, 176 (67 ± 9 years; 72 [41%] female, 115 [65%] Black) completed the graded treadmill exercise test at baseline and the 6-month follow-up. Compared with the control group at the 6-month follow-up, SET significantly decreased overall mean systolic BP (–12 mm Hg; P < .001), PP (–9 mm Hg; P < .001), and HR (–7 b/min; P < .01) during a graded treadmill exercise test but not diastolic BP. Among participants randomized to SET, a greater decrease in systolic BP, PP, and HR during a graded treadmill exercise test was significantly associated with a greater improvement in 6-minute walk distance (systolic BP, r = –0.19 [P = .03] and PP, r = –0.23 [P < .01]; and HR, r = –0.21 [P < .01]) and with maximal treadmill walking distance (systolic BP, r = –0.21 [P < .01] and PP, r = –0.17 [P = .03]) at the 6-month follow-up. A greater decrease in the HR during a graded treadmill exercise test was significantly associated with a better WIQ distance score (r = –0.27; P = .03) at the 6-month follow-up. ConclusionsIn people with PAD, compared with a control group, SET improved cardiovascular health, measured by changes in BP and HR during exercise. The degree of improvement in cardiovascular health correlated with the degree of improvement in walking performance in people with PAD. NCT: 01408901.

Somatic Comorbidities and Cardiovascular Safety in Ketamine Use for Treatment-Resistant Depression.

Background and Objectives: There is evidence for ketamine efficacy in treatment-resistant depression (TRD). Several safety and tolerability concerns arise that some psychotropic agents may provide blood pressure or/and heart rate alterations. The aim of this study is to review blood pressure measurements in course of the treatment with ketamine on treatment refractory inpatients with somatic comorbidities in the course of MDD and BP. Materials and Methods: The study population of 49 patients comprised MDD and BP subjects treated with ketamine registered in the naturalistic observational protocol of treatment-resistant mood disorders (NCT04226963). Results: The conducted analysis showed that among people suffering from hypertension there is a higher increase in systolic blood pressure (RR) after infusion 2 (p = 0.004) than among people who do not suffer from hypertension. Patients with hypertension have a higher increase in diastolic RR compared to those not suffering from hypertension (p = 0,038). Among the subjects with diabetes mellitus, significant differences occurred for infusions 2 (p = 0.020), 7 (p = 0.020), and 8 (p = 0.035) for heart rate (HR), compared to subjects without diabetes mellitus. A higher increase in diastolic RR was noted in the group of subjects suffering from diabetes mellitus (p = 0.010) compared to those who did not. In the hyperlipidemic patients studied, a significantly greater decrease in HR after infusion 5 (p = 0.031) and systolic RR after infusion 4 (p = 0.036) was noted compared to nonpatients. People after a stroke had significantly higher increases in diastolic RR after infusions 4 (p = 0.021) and 6 (p = 0.001) than those who did not have a stroke. Patients suffering from epilepsy had a significantly greater decrease in systolic RR after the 8th infusion (p = 0.017) compared to those without epilepsy. Limitations: The study may be underpowered due to the small sample size. The observations apply to inhomogeneous TRD population in a single-site with no blinding and are limited to the acute administration. Conclusions: This study supports evidence for good safety and tolerability profile for short-term IV ketamine use in TRD treatment. However, risk mitigation measures are to be considered in patients with metabolic and cardiovascular comorbidities.

Autonomic Activation During Face Cooling is Not Attenuated in Healthy Adults with a History of Concussion

Recent evidence indicates that physiological recovery from a concussion appears to take longer than clinical recovery. We have shown that symptomatic concussed patients have impaired cardiac parasympathetic activity and attenuated sympathetically‐mediated increases in blood pressure during face cooling (FC) vs. healthy controls. However, it is not known if the attenuated responses to FC persist in asymptomatic healthy adults who reported experiencing a concussion more than one year ago.PURPOSEWe tested the hypothesis that asymptomatic healthy active adults who experienced a concussion more than one year ago have diminished autonomic activation during FC vs. healthy active adults without a history of concussion.METHODSThirteen healthy adults without a history of concussion within one year of testing performed a FC test. Subjects were retrospectively grouped into those who reported experiencing a concussion more than a year ago (n=5, CH) and those without a history of concussion (n=8, NH). After 10 min of supine rest, a pliable plastic bag filled with ice water (~0° C) was placed on the forehead, eyes and cheeks for 3 min. Heart rate (HR, 3‐lead ECG), mean arterial pressure (MAP, finger photoplethysmography), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were continuously recorded. Total peripheral resistance (TPR) was calculated as MAP/cardiac output. Root mean square of successive differences in R‐R interval (RMSSD) and high‐frequency power (HF) were calculated from spectral analysis of the R‐R interval (RRI) to estimate cardiac parasympathetic activity. Data were analyzed every 1 min and reported as the mean of the change from baseline (D) ± SD.RESULTSAt baseline, there were no differences between groups for HR (NH: 65±14; CH: 65±5 bpm, P=0.95), MAP (NH: 96± 7; CH: 94 ± 10 mmHg, P=0.67), SBP (NH: 130 ± 15; CH: 132 ± 13 mmHg, P=0.84), DBP (NH: 75 ± 5; CH: 74± 8 mmHg, P=0.77), TPR (NH: 17 ± 8; CH: 13± 1 mmHg, P=0.32), and RRI (NH: 990 ± 510; CH: 666 ± 407 ms, P=0.34). RMSSD (NH: 155 ± 85; CH: 50 ± 30 ms, P=0.05) and HF (NH: 3965 ± 1283; CH: 430± 550 ms2, P=0.01) were lower at baseline in CH. During FC, there were no main effects of group for DMAP (P=0.69), DSBP (P=0.86), DDBP (P=0.31), DTPR (P=0.22), DRMSSD (P=0.27), or DHF (P=0.97). During FC, DHR for NH was different vs. CH at Min 1 (NH: 5±4; CH: −4±7 bpm, P=0.01), Min 2 (NH: 1 ± 5; CH: −12 ± 9 bpm, P&lt;0.01), and Min 3 (NH: 3 ± 9; CH: −9 ± 5 bpm, P&lt;0.01). During FC, DRRI in NH was different vs. CH at Min 1 (NH: −68 ± 81; CH: 188 ± 240 ms, P=0.06), Min 2 (NH: −8 ± 130; CH: 253 ± 264 ms, P=0.06), and Min 3 (NH: −67 ± 210; CH: 31 ± 55 ms, P=0.06).CONCLUSIONThese preliminary data indicate that resting cardiac parasympathetic activity is lower in patients with a history of concussion. Despite a greater decrease in heart rate, there were no differences in markers of cardiac parasympathetic activity and sympathetically‐mediated increases in blood pressure during FC between individuals with a history of concussion vs. individuals with no history of concussion. More frequent assessments of the autonomic responses to FC are warranted to determine the normal progression of physiological recovery from concussion.Support or Funding InformationSupported by the National Center for Advancing Translational Sciences of the NIH Pilot Grants Award Program UL1TR001412

Acute volume expansion decreased baroreflex response after swimming but not after running exercise training in hypertensive rats

ABSTRACTBackground: Physical training (ET) is important to restore the reflex sensitivity involved in controlling blood pressure in various diseases. Recent investigations have demonstrated an interaction between cardiopulmonary baroreceptors and arterial baroreflex during dynamic exercise.Objective: Considering that acute and chronic hemodynamic responses to swimming (SW) are different from the race (RUN), the objective of this study was to evaluate the effect of SW and RUN on baroreflex response before and after acute volume expansion in spontaneously hypertensive rats (SHR).Methods: SHR were divided into three groups: RUN, SW and sedentary (SED) groups. After training, the mean arterial pressure (MAP) and heart rate (HR) were recorded. Baroreflex response was assessed before and after acute volume expansion.Results: Both ET conditions reduced basal levels of HR and MAP. The first volume of injected isotonic saline solution (1.25% of body weight) produced a greater decrease in HR for the SW group (−105.8 ± 8.7 bpm) compared to RUN groups (−68 ± 5.2 bpm) and SED (−49.8 ± 7.2 bpm). Both training modalities increase the baroreflex response in relation to the SED group, but after the total volume expansion, the SW group presented attenuated response (0.7 ± 0.1 μPIms/mmHg) compared to RUN (1.5 ± 0.17 PIms/mmHg) and was not different from SED group (0.8 ± 0.2 mPIms/mmHg).Conclusion: The results show that the swim-trained group has a different baroreflex response to that observed by the run-trained group after the activation of the load receptors by saline expansion.

Endothelial Phenotype Evoked by Low Dose Carvedilol in Pulmonary Hypertension.

Background: The therapeutic benefits of β-blockers are well established in left heart failure. The Pulmonary Arterial Hypertension Treatment with Carvedilol for Heart Failure [PAHTCH] study showed safety and possible benefit of carvedilol in pulmonary arterial hypertension (PAH) associated right heart failure over 6 months. This study aims at evaluating the short-term cardiovascular effects and early mechanistic biomarkers of carvedilol therapy.Methods: Thirty patients with pulmonary hypertension (PH) received low dose carvedilol (3.125 mg twice daily) for 1 week prior to randomization to placebo, low-dose, or dose-escalating carvedilol therapy. Echocardiography was performed at baseline and 1 week. Exercise capacity was assessed by 6 min walk distance (6MWD). The L-arginine/nitric oxide pathway and other biological markers of endothelial function were measured.Results: All participants tolerated 1 week of carvedilol without adverse effects. After 1 week of carvedilol, 6MWD and heart rate at peak exercise did not vary (both p > 0.1). Heart rate at rest and 1 min post walk dropped significantly (both p < 0.05) with a trend for increase in heart rate recovery (p = 0.08). Right ventricular systolic pressure (RVSP) decreased by an average of 13 mmHg (p = 0.002). Patients who had a decrease in RVSP of more than 10 mm Hg were defined as responders (n = 17), and those with a lesser drop as non-responders (n = 13). Responders had a significant drop in pulmonary vascular resistance (PVR) after 1 week of carvedilol (p = 0.004). In addition, responders had a greater decrease in heart rate at rest and 1 min post walk compared to non-responders (both p < 0.05). Responders had higher plasma arginine and global bioavailability of arginine at baseline compared to non-responders (p = 0.03 and p = 0.05, respectively). After 1 week of carvedilol, responders had greater increase in urinary nitrate (p = 0.04). Responders treated with carvedilol had a sustained drop in RVSP and PVR after 6 months of carvedilol with no change in cardiac output.Conclusions: Low-dose carvedilol for 1 week can potentially identify a PH responder phenotype that may benefit from β-blockers that is associated with less endothelial dysfunction.Clinical Trial Registration: http://www.clinicaltrials.gov. identifier: NCT01586156.

PHARMACOGENETIC FEATURES OF THERAPY OF PATIENTS WITH ATHEROSCLEROSIS

The complexity of therapy of lipid metabolism disorders is not only in comorbidity and polypragmasia, but also in predicting a genetically determined response to the treatment. The aim of our work was to study the pharmacogenetics features of pharmacotherapy of patients with non-alcoholic fatty liver disease, with various forms of IHD, and patients taking statins. We investigated 4 study groups: I — 60 patients with 2 type of diabetes and non-alcoholic fatty liver disease (APOE polymorphism); II — 187 patients with IHD (eNOS, AGTR2, CYP2D6 polymorphisms); III — 111 people with AH and CHF (polymorphisms: AGT: 704 (Met235Thr), AGT:521 (Thr174Met), AGTR1: 1166, AGTR2: 1675, CYP11B2: -344, GNB3: 825, ADD1: 1378 (Gly460Trp), NOS3: -786); IV — 62 patients taking atorvastatin (SLCO1B1*5 polymorphism). Patients with E2, E4 alleles of the APOE gene, taking essential phospholipids, improved parameters of total cholesterol, HDL, LDL, CA, AP; patients with E3 alleles had a positive dynamics of cholesterol, HDL, TG, LDL, VLDL, CA, urea. Patients having “slow” allelic variants of the gene CYP2D6*10, CYP2D6*4 had received metoprolol, had greater decrease in heart rate: 1.6 times for CYP2D6*10, 1.7 — for CYP2D6*4. Earlier debut of IHD is noted in patients with TT variants of the eNOS gene comparing the patients with GG and GT variants. Dosages of perindopril depend on AGTR2 gene polymorphisms. The prevalence of polymorphisms AGTR2: 1675, CYP11B2: -344, NOS3: -786, AGT: 704, GNB3: 825 increases with the increase in the stage of CHF. The parameters of intracardiac hemodynamics in patients with CHF are associated with AGT: 704, NOS3:-786, GNB3: 825, ADD1: 1378, AGT: 521 polymorphisms. Allele C of the SLCO1B1*5 gene is associated with an additional risk of statin-induced myopathy. So the treatment of diseases associated with atherosclerosis, needs using of a personalized approach for more effective and safe therapy.

Increased Sympathetic Outflow Induces Adaptation to Acute Experimental Pain.

There are interrelationships between the autonomic nervous system and pain. This study aims to explore the effect of different autonomic manipulations on pain perception and modulation. Twenty healthy subjects (10 men and 10 women, mean age 25 ± 3 years) participated in this single-blinded, semi-randomized, controlled study, which included 2 study visits. Warm detection thresholds, heat pain thresholds, conditioned pain modulation (CPM), and pain adaptation were tested before and after administration of phenylephrine, clonidine, yohimbine, and saline. Changes in heart rate and blood pressure were found after all the pharmacological interventions. The only effect on pain measures was that yohimbine enhanced pain adaptation capacity while phenylephrine reduced it (P = 0.032). Several significant correlations were found between autonomic and pain parameters; greater decreases in heart rate after phenylephrine were associated with reduced pain ratings (r2 = 0.288, P = 0.018). In addition, enhanced pain adaptation was associated with higher total vascular resistance (r2 = 0.442, P = 0.01). Different effects of acute autonomic manipulations on experimental pain were found: an increase in sympathetic tone induced by yohimbine led to reduced pain sensitivity; a decrease in sympathetic tone with no effect on vagal-parasympathetic tone induced by phenylephrine led to reduction in pain adaptation capacity; and a decrease in sympathetic tone and increase in vagal parasympathetic tone by clonidine led to no change in pain adaptation capacity. While increased sympathetic outflow does facilitate pain adaptation, activation of either the sympathetic or parasympathetic limbs of the autonomic nervous system does not affect pain thresholds or CPM. Finally, a correlation exists between nociception and cardiovascular parameters only due to baroreflex activation.

In utero testosterone exposure influences physiological responses to dyadic interactions in neurotypical adults.

We investigated how different levels of prenatal exposure to testosterone influence physiological reactions to dyadic interactions, hypothesising that higher levels of prenatal testosterone are linked to greater physiological responses. Autonomic nervous system responses to dyadic interactions focussed on social or physical norms were measured. Physiological assessment of excitability (heart rate, facial temperature) and a behavioural assessment (Likert items judgements) were run on 25 neurotypical participants who had distinct testosterone exposure levels in utero. In utero exposure to testosterone was assessed measuring 2D : 4D (ratio between the lengths of the index and the ring fingers). Higher testosterone exposure participants showed greater physiological arousal: a greater heart rate decrease, independent from scenario type (p<0.05), and opposite facial temperature changes in response to social (increase) (vs.) physical scenarios (decrease) were found (Left-cheek: p<0.05; Right-cheek: p<0.05). These findings suggest a long-term influence of prenatal environment on adults' physiological responses during social situations.

Cardiovascular Adaptation to the Nordic Walking or Strength Type of Exercising For Health Promotion

Tikslas – palyginti skirtingo pobūdžio sveikatą stiprinančių pratybų (jėgos ugdymo pratimų ir šiaurietiškojo ėjimo) poveikį širdies ir kraujagyslių sistemai. Tyrime dalyvavo 28 asmenys, jie buvo santykinai sveiki, nesiskundžiantys širdies ir kraujagyslių sistemos funkcijos sutrikimais, turintys gydytojo leidimą dalyvauti sveikatos stiprinimo fiziniais pratimais pratybose. Tiriamieji buvo atrinkti atsitiktine tvarka ir suskirstyti į dvi grupes, kurios pagal amžiaus vidurkį, kūno masę, lytį, ramybės širdies susitraukimų dažnį (ŠSD) ir arterinį kraujo spaudimą (AKS) statistiškai reikšmingai nesiskyrė. Tiriamajam kontingentui buvo taikomos skirtingo pobūdžio sveikatą stiprinančios pratybos. Pirmajai (I) grupei buvo taikomas šiaurietiškasis ėjimas, o antrajai (II) – pratybos sporto salėje. Abiem grupėms iki 90 min trukmės pratybos vykdytos tris kartus per savaitę šešis mėnesius. Tiriamųjų širdies ir kraujagyslių sistemos būklei bei fiziniam parengtumui vertinti buvo naudojamas Rufjė fizinio krūvio mėginys. AKS buvo matuojamas prieš krūvį, po krūvio ir kas minutę atsigavimo metu. Viso šio funkcinės būklės vertinimo metu nepertraukiamai buvo registruojama 12 standartinių derivacijų elektrokardiograma (EKG). Buvo analizuojami šie EKG rodikliai: ŠSD ir JT intervalo trukmė, bei vertinamos ST segmento depresijos reikšmės, registruotos ramybės metu ir didžiausios atliekant dozuoto krūvio mėginį. Po šešių mėnesių trukmės sveikatą stiprinančių pratybų sveikų vidutinio amžiaus žmonių ramybės ŠSD ir AKS nepakito (p > 0,05). Po šešių mėnesių trukmės skirtingo pobūdžio pratybų reakcija į fizinį krūvį skyrėsi: po šiaurietiškojo ėjimo programos ŠSD padidėjimas Rufjė fizinio krūvio mėginio metu sumažėjo, o po pratybų sporto salėje ŠSD reakcija į fizinį krūvį nepakito (p > 0,05). Paaiškėjo, kad šešių mėnesių trukmės šiaurietiškojo ėjimo pratybos padarė poveikį ST segmento depresijos reikšmėms atliekant Rufjė fizinio krūvio mėginį – nustatytas ST segmento depresijos mažėjimas (p < 0,05). Šešių mėnesių trukmės pratybos sporto salėje neturėjo įtakos ST segmento depresijos pokyčiams atliekant Rufjė fizinio krūvio mėginį (p > 0,05). Šešių mėnesių sveikatos stiprinimo pratybos, kuriose pagrindinis krūvis buvo šiaurietiškasis ėjimas, ir pratybos, kurios buvo atliekamos sporto salėje su treniruokliais, turėjo teigiamos įtakos sveikatą stiprinančių asmenų širdies ir kraujagyslių sistemos funkcinei būklei. Tyrimas atkleidė keletą šiaurietiškojo ėjimo pranašumų stiprinant sveikatą. Po pusės metų eksperimento šiaurietiškąjį ėjimą praktikavusiųjų grupės tiriamiesiems, atliekantiems dozuoto fizinio krūvio užduotis, mažiau padidėja ŠSD ir pastebimas mažesnis funkcinių išeminių reiškinių pasireiškimas miokarde nei jėgos ugdymo pratimus sporto salėje praktikavusiems tiriamiesiems.

Modeling of Amiodarone Effect on Heart Rate Control in Critically Ill Patients with Atrial Tachyarrhythmias.

Amiodarone is the gold-standard medication to control heart rate in critically ill patients with atrial tachyarrhythmias (ATs); however, effective doses and covariates influencing its efficacy remain unknown. We therefore performed pharmacodynamic modeling of heart rate reduction induced by amiodarone in these patients. This observational study included 80 consecutive severely ill patients receiving amiodarone to treat ATs. A total of 1348 time-heart rate observations with 361 amiodarone dose administrations were analyzed during a period of up to 6days after hospital treatment initiation using a nonlinear mixed-effect model. Pretreatment with amiodarone before intensive care administration, paroxysmal versus persistent AT, catecholamine infusion, and fluid and magnesium loading were among the covariates assessed in the model. In case of paroxysmal AT in a patient not pretreated with amiodarone, a 300mg intravenous loading dose combined with an 800mg oral dose on the first day, followed by 800mg/day orally for 4days was effective in achieving a heart rate between 80 and 115bpm within the first day, and to maintain it during the next 4days. Corresponding doses were twice as high in patients with persistent AT. Use of intravenous magnesium (p<0.02) and fluid loading (p<0.02) was associated with an earlier and greater heart rate decrease, while use of dobutamine had an opposite influence (p<0.05). In critically ill patients with AT, the dose of amiodarone required to control heart rate is influenced by the type of AT and by other easily measurable conditions which may allow better individualization of amiodarone dosing.

Comparison of effects of rocuronium bromide versus vecuronium bromide on hemodynamic parameters during anaesthesia for elective surgical procedures

Background: Understanding haemodynamic effects of muscle relaxants may help us in selection of most appropriate muscle relaxant in a given case after considering preoperative cardiac status, preoperative medications, anaesthetic drugs to be used, nature of surgery and desirable intraoperative hemodynamics. Hemodynamic effects of rocuronium are not as clear as vecuronium. Present study was conducted to compare haemodynamic parameters during general anaesthesia for elective surgical procedures with vecuronium vs. rocuronium as muscle relaxant. Methods: Haemodynamic effects of vecuronium 0.15 mg/kg and 0.9 mg/kg of rocuronium was evaluated in patients (25 patients in each group) undergoing elective surgical procedures not lasting more than two hours. During this study period patients were evaluated for heart rate (HR), systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP). Results: When both groups were compared, degree of fall in heart rate was more in vecuronium group (V group) compared to rocuronium group at all-time intervals after administration of drug. The fall in mean heart rate in V group was significant at two minutes after administration of muscle relaxant when compared to R group i.e.77.12±9.96 vs. 85.04±12.82 (p<0.05) and was highly significant at 3 minutes after administration of drug i.e. 76.12±9.67 vs. 85.44±12.47 (p<0.001). After induction and administration of vecuronium or rocuronium there was fall in systolic blood pressure, diastolic blood pressure and mean arterial pressure in both the groups when these parameters were recorded before laryngoscopy with slightly more but comparatively non-significant fall in these parameters in vecuronium group. Intraoperatively these parameters were comparable in both groups and no significant difference from baseline was observed in these parameters in both groups thereby showing good haemodynamic stability. Conclusions: Vecuronium is associated with greater decrease in heart rate than rocuronium in clinical doses. No increase in heart rate was observed with rocuronium in doses used. In all other aspects (SBP, DBP, MAP) haemodynamic effects were similar in both groups with slightly greater but non-significant fall observed after administration of vecuronium group.

Chronotropic effect of propofol or alfaxalone following fentanyl administration in healthy dogs

ObjectiveTo compare the effect of alfaxalone and propofol on heart rate (HR) and blood pressure (BP) after fentanyl administration in healthy dogs. Study designProspective, randomised clinical study. AnimalsFifty healthy client owned dogs (ASA I/II) requiring general anaesthesia for elective magnetic resonance imaging for neurological conditions. MethodsAll dogs received fentanyl 7 μg kg−1 IV and were allocated randomly to receive either alfaxalone (n = 25) or propofol (n = 25) to effect until endotracheal (ET) intubation was possible. Heart rate and oscillometric BP were measured before fentanyl (baseline), after fentanyl (Time F) and after ET intubation (Time GA). Post-induction apnoea were recorded. Data were analysed using Fisher’s exact test, Mann Whitney U test and one-way anova for repeated measures as appropriate; p value <0.05 was considered significant. ResultsDogs receiving propofol showed a greater decrease in HR (-14 beat minute−1, range -47 to 10) compared to alfaxalone (1 beat minute−1, range -33 to 26) (p = 0.0116). Blood pressure decreased over the three time periods with no difference between groups. Incidence of post-induction apnoea was not different between groups. ConclusionFollowing fentanyl administration, anaesthetic induction with propofol resulted in a greater negative chronotropic effect while alfaxalone preserved or increased HR. Clinical relevanceFollowing fentanyl administration, HR decreases more frequently when propofol rather than alfaxalone is used as induction agent. However, given the high individual variability and the small change in predicted HR (-7.7 beats per minute after propofol), the clinical impact arising from choosing propofol or alfaxalone is likely to be small in healthy animals. Further studies in dogs with myocardial disease and altered haemodynamics are warranted.

Clinical Significance of Early Smoking Withdrawal Effects and Their Relationships With Nicotine Metabolism: Preliminary Results From a Pilot Study

Although the early time course of smoking withdrawal effects has been characterized, the clinical significance of early withdrawal symptoms and their predictors are unknown. This study evaluated the relationships of early smoking withdrawal effects with quit attempt outcomes and the rate of nicotine metabolism. Eleven treatment-seeking smokers abstained from smoking for 4 hr in the laboratory before a quit attempt. Withdrawal measures included heart rate, sustained attention, and self-report. Following baseline assessment, withdrawal measures were administered every 30 min. At the conclusion of the 4-hr early withdrawal session, participants received a brief smoking cessation intervention and then returned 1 week and 12 weeks later for outcome assessments that included biochemically confirmed smoking abstinence, cigarettes smoked in the past 24hr, and self-reported withdrawal symptoms. The rate of nicotine metabolism was estimated at intake with the nicotine metabolite ratio (trans-3'-hydroxycotinine/cotinine) measured in saliva. Greater self-reported negative affect and concentration difficulty during early withdrawal, most notably anxiety, were related with poorer quit attempt outcomes. There was some indication that although a faster increase in craving and greater hunger during early withdrawal were associated with more favorable outcomes, a greater decrease in heart rate during this time was associated with poorer outcomes. Faster nicotine metabolism was related to a faster increase in anxiety but a slower increase in craving during early withdrawal. These findings lend support to the clinical significance of early smoking withdrawal effects. The rate of nicotine metabolism may be a useful predictor of early withdrawal symptoms.

1454 Impact of a Cham Jam Intervention on Physical Fitness in Elementary School Students

Background and AimsCHAM JAM, a classroom-based physical activity intervention, has been effective in increasing physical activity levels in elementary school students. The objective if this study was to determine the...

Cardiorespiratory and neuroendocrine changes induced by methadone in conscious and in isoflurane anaesthetised dogs

The aim of this study was to compare the cardiorespiratory and neurohormonal effects of methadone in conscious and in isoflurane anaesthetised dogs. Six mature dogs (28.0 ± 3.8 kg bodyweight) received intravenous (IV) methadone (1mg/kg) three times, once when conscious and twice during isoflurane anaesthesia (with a wash-out period of 1 week). The vasopressin antagonist relcovaptan (0.1mg/kg IV) was administered before the methadone either during the first or second (selected randomly) isoflurane anaesthesia to evaluate the contribution of vasopressin to methadone-associated vasoconstriction. Cardiorespiratory data, plasma catecholamines and serum vasopressin were recorded before (baseline) and for 90 min after methadone. Methadone induced dysphoria in all conscious dogs and significantly (P<0.05) increased mean arterial pressure (MAP), catecholamines, and vasopressin concentrations. During anaesthesia, in addition to significantly greater decreases in heart rate (HR) and cardiac index (CI) than during the conscious state, methadone induced apnoea and mechanical ventilation was necessary in all dogs. In anaesthetised animals, methadone administration significantly increased vasopressin concentrations and systemic vascular resistance index (SVRI), while MAP did not differ from baseline. Relcovaptan administration did not modify the increase in SVRI associated with methadone injection during anaesthesia. Increases in plasma catecholamines may account for the slight decreases in HR and CI seen after methadone administration in conscious dogs. In contrast, isoflurane enhanced the intensity of the cardiorespiratory changes induced by methadone. Vasoconstrictive responses associated with methadone did not appear to be induced by vasopressin.

The combination of OLmesartan and a CAlcium channel blocker (azelnidipine) or candesartan and a calcium channel blocker (amlodipine) in type 2 diabetic hypertensive patients: The OLCA study

Angiotensin II receptor blockers (ARB) are often co-administered with a calcium channel blocker (CCB) for treating hypertension. In this open-label randomised study, untreated diabetic hypertensive patients were randomised to receive either olmesartan 20 mg/day or candesartan 8 mg/day for 12 weeks. Patients with blood pressure exceeding 130/80 mm Hg received add-on 16 mg/day azelnidipine to ongoing olmesartan (OL group) or 5 mg/day amlodipine to ongoing candesartan (CA group) for 24 weeks. Home-measured and clinic-measured blood pressure decreased in both groups. Fasting blood glucose, haemoglobin A1c (HbA1c) and urinary albumin levels decreased significantly in the OL group but not in the CA group. In conclusion, this study revealed clinically relevant differences between two combinations of an ARB+CCB in diabetic hypertensive patients. Olmesartan and azelnidipine had a more persistent early morning antihypertensive effect and produced greater decreases in heart rate, fasting blood glucose and HbA1c (National Glycohemoglobin Standardization Program values) levels, and microalbuminuria than did candesartan and amlodipine.

Altered baroreflex and autonomic modulation in monosodium glutamate-induced hyperadipose rats

We aimed to examine the cardiovascular function by tonic and baroreflex alterations in obese rats induced by monosodium glutamate (MSG). Neonatal male Wistar rats were injected with MSG (4 mg/g body weight) or equimolar saline (control, C). At 90 days, all rats were anesthetized for catheterization of the femoral artery for mean arterial pressure (MAP) and heart rate (HR) recordings in the conscious state. After baseline, we performed IV treatment with hexamethonium (25 mg/kg), or atropine (1 mg/kg) or propranolol (3 mg/kg). We also performed the spectral analysis of heart rate variability (HRV) and baroreflex sensitivity. Baseline comparison showed that obese rats are hypertensive compared with control (C=110±2 mmHg; MSG=: 123±3 mmHg, P<0.05). After ganglionic blockade with hexamethonium the differences in MAP between control and obese rats disappeared. Beta adrenergic blockade with propranolol induced a greater decrease in heart rate compared with control. The analysis of HRV showed that obese rats have increased modulation by both components of the autonomic nervous system compared with control rats. The baroreflex gain showed increased sensitivity for the parasympathetic component in the obese rats (C=−2.41±0.25; MSG=−3.34±0.23 bpm/mmHg) compared with control. Our data suggest that both components of autonomic cardiac tonus and the parasympathetic component of the baroreflex sensitivity are increased in the MSG obese rat. It is possible that the parasympathetic alterations observed in these MSG obese rats may have originated from central areas of cardiovascular control.