Higher Incidence Of Bradycardia Research Articles

Comparison of Magnesium Sulfate and Dexmedetomidine as an Adjuvant to 0.5% Ropivacaine in Infraclavicular Brachial Plexus Block.

Background:Magnesium sulfate and dexmedetomidine were used as adjuvants to local anesthesia to improve the quality of regional anesthesia.Aims:The aim of this study is to evaluate and compare the effects of magnesium sulfate and dexmedetomidine when added to ropivacaine on the quality of infraclavicular brachial plexus block (BPB).Settings and Design:This was a prospective randomized double-blinded controlled study.Patients and Methods:A total of 105 adult patients undergoing surgery in hands, wrist, and forearm using infraclavicular BPB were randomly assigned into three groups. Ultrasound-guided infraclavicular BPB was performed using 35 ml ropivacaine 0.5% diluted with 4 ml normal saline 0.9%. Magnesium sulfate 150 mg and dexmedetomidine 100 μg were added in the magnesium sulfate group and dexmedetomidine group, respectively. Duration of analgesia, onset times and durations of sensory block (SB) and motor block (MB), patient's satisfaction, and complications were recorded.Statistical Analysis:Statistical software SPSS 16 was used for statistical analysis.Results:Dexmedetomidine and magnesium sulfate provided longer duration of analgesia and lesser consumption of postoperative rescue analgesia than the control group (P = 0. 000); dexmedetomidine provided the longest duration of analgesia versus control and magnesium sulfate groups (P = 0.000). Dexmedetomidine provided the quickest onset times and the longest durations of both SB and MB than control and magnesium sulfate groups (P = 0.000). Dexmedetomidine group had higher incidences of bradycardia and hypotension.Conclusions:Magnesium sulfate or dexmedetomidine is a useful adjuvant to ropivacaine for infraclavicular BPB in lengthening the duration of analgesia. Dexmedetomidine provided quicker onset and longer duration of both SB and MB and longer duration of analgesia with lesser consumption of postoperative rescue analgesia; however, it showed a higher incidence of intraoperative hypotension and bradycardia than magnesium sulfate.

Phase I dose-escalation study of long-acting pasireotide in patients with neuroendocrine tumors.

This phase I study aimed at determining the maximum tolerated dose (MTD) and characterizing the safety, tolerability, pharmacokinetics (PKs), and efficacy of pasireotide in patients with advanced neuroendocrine tumors (NETs). Patients were enrolled in two phases: dose-escalation phase (to determine the MTD) at a starting dose of 80 mg pasireotide long-acting release (LAR) i.m. followed by a dose-expansion phase (to evaluate safety and prelimi-nary efficacy). Associations between PK/pharmacodynamic parameters and clinical outcomes were evaluated using linear regression analysis. A total of 29 patients were treated with 80 mg (n=13) and 120 mg (n=16) doses. Most common primary tumor sites included small intestine (44.8%), pancreas (24.1%), and lung (17.2%). No protocol-defined dose-limiting toxicities were observed in the study; however, in post hoc analysis, a higher incidence of bradycardia (heart rate [HR] <40 beats per minute [bpm]) was observed with 120 mg (31.3%) vs 80 mg (0%). Two partial responses (PRs) were observed, both in the 120 mg dose cohort. Pasireotide concentrations correlated with tumor shrinkage, although the association was not statistically significant (P=0.08). Among the biomarkers analyzed, insulin-like growth factor 1 (IGF-1) showed a decreasing trend with increasing pasireotide concentration, while chromogranin A (CgA) and neuron-specific enolase (NSE) levels did not show any dose–response relationship. The most common adverse events in any dose group were hyperglycemia, fatigue, and nausea. MTD was defined at 120 mg for pasireotide LAR in patients with advanced NETs. Although objective radiographic responses were rarely observed with somatostatin analogs, two PRs were observed among 16 patients in the 120 mg cohort. Bradycardia (HR <40 bpm) appears to be a dose-limiting effect; however, the mechanism and clinical significance are uncertain. This study was registered with clinicaltrials.gov (NCT01364415).

Intravenous dexmedetomidine during spinal anaesthesia for caesarean section: A meta-analysis of randomized trials.

ObjectiveTo evaluate the efficacy and safety of spinal anaesthesia using dexmedetomidine for caesarean section.MethodsPubMed, The Cochrane Library, and CNKI were searched for relevant literature.ResultsThe incidence of nausea and vomiting in the dexmedetomidine group was significantly lower than that in the control group (OR = 0.21, 95% CI: 0.12–0.35, P < 0.00001). No difference was found in the incidence of pruritus between the two groups (OR = 1.21, 95% CI: 0.36–4.09, P = 0.76).The dexmedetomidine group had a higher incidence of bradycardia than did the control group (OR = 2.20, 95% CI: 1.02–4.77, P = 0.05). The incidence of shivering in the dexmedetomidine group was significantly lower than that in the control group (OR = 0.20, 95% CI: 0.13–0.32, P < 0.00001). The incidence of hypotension was not different between the two groups (OR = 0.88, 95% CI: 0.49–1.56, P = 0.65).ConclusionDexmedetomidine can decrease the incidence of nausea, vomiting, bradycardia, and shivering with spinal anaesthesia during caesarean section.

Supraclavicular brachial plexus block: Comparison of varying doses of dexmedetomidine combined with levobupivacaine: A double-blind randomised trial

Background and Aims:The ideal dose of dexmedetomidine for brachial plexus block is a matter of debate. This study was carried out to evaluate 50 μg or 100 μg of dexmedetomidine added to 0.5% levobupivacaine, with regard to the duration of analgesia. Our study also sought to assess the onset and duration of sensorimotor blockade, haemodynamic effects, sedation and adverse effects.Methods:One hundred adult patients undergoing upper limb surgeries under supraclavicular brachial plexus block were randomly allocated into two groups. Group LD50 received 29 ml of 0.5% levobupivacaine plus 50 μg of dexmedetomidine diluted in 1 ml of normal saline. Group LD100 received 29 ml of 0.5% levobupivacaine plus 100 μg of dexmedetomidine diluted in 1 ml of normal saline. Duration of analgesia was the primary outcome. Onset and duration of sensorimotor blockade, haemodynamic variables, sedation score, and adverse effects were secondary outcomes. The data were analysed with Students' t-test and Chi-square test.Results:The onset of sensory block and motor block was 14.82 ± 3.8 min and 19.75 ± 6.3 min, respectively, in group LD50, while it was 11.15 ± 1.7 min and 14.3 ± 4.2 min, respectively, in group LD100. The duration of analgesia was significantly prolonged in group LD100 (1033.6 ± 141.6 vs. 776.4 ± 138.6 min; P = 0.001). The incidence of bradycardia and sedation was observed in significantly more patients in group LD100. Significantly fewer patients in group LD100 required rescue analgesia.Conclusion:The 100 μg dose of dexmedetomidine in brachial plexus block hastens the onset and prolongs the duration of sensorimotor blockade and analgesia, but with higher incidence of bradycardia and sedation.

Dexmedetomidine vs propofol sedation reduces delirium in patients after cardiac surgery: A meta-analysis with trial sequential analysis of randomized controlled trials

PurposeIt is uncertain whether dexmedetomidine is better than propofol for sedation in postcardiac surgery patients. The purpose of this meta-analysis was to compare the effects of dexmedetomidine and propofol sedation on outcomes in adult patients after cardiac surgery. MethodsRandomized controlled trials comparing outcomes in cardiac surgery patients sedated with dexmedetomidine or propofol were retrieved from PubMed, Embase, Web of Science, the Cochrane Library, and Clinicaltrials.Gov until May 23, 2016. ResultsA total of 969 patients in 8 studies met the selection criteria. The results revealed that dexmedetomidine was associated with a lower risk of delirium (risk ratio, 0.40;95% confidence interval [CI], 0.24-0.64; P=.0002), a shorter length of intubation (hours; mean difference, -0.95; 95% CI, -1.26 to -0.64; P<.00001), but a higher incidence of bradycardia (risk ratio 3.17; 95% CI, 1.41-7.10; P=.005) as compared to propofol. There were no statistical differences in the incidence of hypotension or atrial fibrillation, or the length of intensive care unit stay between dexmedetomidine and propofol sedation regimens. ConclusionsDexmedetomidine sedation could reduce postoperative delirium and was associated with shorter length of intubation, but might increase bradycardia in patients after cardiac surgery compared with propofol.

The effect of two different doses of dexmedetomidine to attenuate cardiovascular and airway responses to tracheal extubation: a double blind randomized controlled trial

Background: The objective of the study is to assess the effectiveness of two different doses of dexmedetomidine, an alpha 2 adrenergic agonist, to attenuate the cardiovascular and airway responses to tracheal extubation and to observe the adverse effects. Methodology: Ninety ASA grade I and II patients aged 18-50 years were randomized into three groups; A, B, and C to receive dexmedetomidine 0.5µg/kg, 1µg/kg and normal saline placebo respectively about 15 minutes before discontinuation of inhalational agent. The heart rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were recorded during administration of drug, before extubation, during extubation, at 1, 3 minutes and every 5 minutes thereafter. Extubation quality was assessed on a 5 point scale and sedation by Ramsay sedation score. Results: There was significant decrease in heart rate and mean arterial pressure (p<0.001) during extubation in group A and B. Ninety percent of patients in group A, 93.3% patients in group B and 16.7% in group C could be extubated smoothly. The average time to extubate was 12.13±2.11, 14.08±3.19 and 10.27±2.09 minutes in groups A, B, and C respectively (P value <0.001). Higher incidence of bradycardia (p<0.001) was observed in Group A and B whereas incidence of breath holding was higher in group C (p=0.024). Conclusion: A dose of 0.5µg/kg of dexmedetomidine administered as a bolus infusion before extubation attenuates the stress response to extubation as effectively as 1µg/kg. Higher sedation scores and longer time to extubate are seen with a dose of 1µg/kg without causing respiratory depression.

Comparative evaluation of two different loading doses of dexmedetomidine with midazolam-fentanyl for sedation in vitreoretinal surgery under peribulbar anaesthesia.

Background and Aims:Midazolam-fentanyl (MDZ:FEN) combination has been routinely used for intravenous sedation in ophthalmic surgeries. Dexmedetomidine (DEX), a recent α2 adrenoreceptor agonist indicated for sedation for ophthalmic use at a loading dose of 0.5 μg/kg over 10 min, can cause deeper plane of sedation and surgeon dissatisfaction. Therefore, we proposed to evaluate the efficacy and safety of two different loading doses of DEX.Methods:In a prospective study, 60 patients aged 50-70 years, scheduled for retinal surgery under peribulbar block were divided equally to receive either MDZ:FEN or DEX 0.5 μg/kg (DEX full) or DEX 0.25 μg/kg (DEX half) loading dose over 10 min followed by titrated maintenance dose of DEX 0.25-0.4 μg/kg/h. Vital parameters, level of sedation (Ramsay Sedation Scale 1–6), effect on respiration and surgeon satisfaction were assessed at regular intervals. Surgeon satisfaction score (0–3) was noted.Results:‘DEX half’ group patients had predominantly stable haemodynamics, level 3 sedation and surgeon satisfaction score of 2–3 (good to excellent operating conditions). This group had no vomiting and no respiratory depression. ‘DEX full’ group had a higher incidence of bradycardia, hypotension, level 4 sedation (Ramsay Sedation Scale) and lower surgeon satisfaction. Incidence of nausea and vomiting was higher in MDZ:FEN group compared to other two groups.Conclusion:DEX 0.25 μg/kg loading dose over 10 min followed by titrated maintenance dose is an effective alternative to MDZ:FEN and provides controlled (level 3) sedation and stable haemodynamics maximising surgeon satisfaction. Avoiding narcotic analgesics with its associated post-operative nausea and vomiting is an additional benefit.

Effectiveness of Dexmedetomidine as an Adjunct Agent for Sedation during ERCP

Objectives: To evaluate dexmedetomidine as an adjunct drug to propofol for sedation during ERCP, and its effects on perfusion index (PI) which could be used as an indicator for analgesia level. Methods: 76 patients ASA (I-III) scheduled for ERCP procedure were randomly classified to either dexmedetomidine/propofol group or propofol group. In dexmedetomidine/propofol group, sedation was induced by dexmedetomidine (0.7 μg/kg) and propofol (50 mg) followed by infusion of dexmedetomidine (0.4 μg/kg/h) and propofol (0.5-1 mg/kg/h). In propofol group, sedation was induced by propofol (50 mg) followed by propofol infusion (0.5-1 mg/kg/h). HR, SBP, DBP, RR, SPO2 and PI were continuously monitored and recorded at the time points (T0 to T8). Results: Comparing dexmedetomidine/propofol group versus propofol group; PI values showed significant increase at T2 to T7 (pE‚0.001), HR values showed significant decrease at T1 to T8 (p 0.013 at T1 and 0.001 at T2 to T8), SBP values showed significant decrease at T1 to T8 (p=0.002 at T1, 0.001 at T2 to T7 and 0.004 at T8) and DBP values showed significant decrease at T4 to T6 (p value 0.008, 0.002 and 0.003 at T4.T5 and T6). RR and SPO2 values were comparable in both groups. In dexmedetomidine/propofol group, the propofol dosage was significantly lower (p value 0.001) and the recovery time was significantly higher (p value 0.001) than that of propofol group, while the procedure time was comparable between both groups. Dexmedetomidine/propofol group showed higher incidence of bradycardia than propofol group (p value 0.035) while propofol group showed more cases with tachycardia (p value 0.016) and more cases with airway obstruction (p value 0.026). Conclusion: dexmedetomidine is a useful adjunct drug for sedation during ERCP procedure.

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Introduction: A variety of medications are used to facilitate tracheal intubation (TI) in critically ill children in pediatric ICUs (PICUs), with the goal of achieving a level of sedation that will generate favorable intubation conditions. Options for sedation include narcotics, benzodiazepines, ketamine, propofol, and etomidate; additionally, neuromuscular blockade may be employed. Often specific medications are selected for at risk patients to minimize adverse TI Associated Events (TIAE's). Traditionally, vagolytics (atropine/glycopyrrolate) are used as adjunctive TI medications to prevent bradycardia during TI induction. In addition, ketamine is often chosen to prevent medication-induced hypotension during TI induction in critically ill children. However, the data to support these practices are limited. We hypothesize: 1. In patients at risk for bradycardia, the use of a vagolytic agent as part of the TI induction regimen will be associated with a lower incidence of bradycardia, when compared to regimens without vagolytics; 2. In patients at risk for hypotension, the administration of ketamine as part of the TI induction regimen will be associated with a lower incidence of hypotension during TI, when compared to regimens without ketamine. Methods: With IRB approval, consecutive TI quality improvement data from 19 PICUs were prospectively collected from 7/2010 to 12/2012 into the National Emergency Airway Registry for Children (NEAR4KIDS) with > 95% compliance at each site. Adverse TIAEs were a priori defined with consensus-based operational definitions. These include physiological responses such as bradycardia, hypotension or cardiac arrest with/without return of spontaneous circulation. Fisher's exact test was used as univariate analysis with p<0.05 considered significant. Multivariate logistic regression was used to adjust for patient-level confounders. Results: There were 3382 primary TIs reported across the 19 centers. The median patient age was 1 year [IQR:0-7]. Fentanyl and midazolam were the most commonly used TI induction medications. Overall, fentanyl was used in 63% of TIs (22-90% at each site), and midazolam was used in 58% of TIs (7-82% at each site). Neuromuscular blockers were used in 3111 (92%, 75-95% at each site). Rocuronium was the most commonly used paralytic (69% of all neuromuscular blockers). Propofol was used in 15% of TI's (range 2-84%). Both Etomidate (1.7 %) and succinylcholine (0.74%) were used very infrequently. Vagolytics were used in 37% of TIs, more commonly for infants <1yr (51%) vs. children > 1yr (28%, p<0.001). Contrary to our hypothesis, vagolytic use was associated with a higher incidence of bradycardia (2.4% vs.0.9%, p=0.002), even after adjusting for diagnostic category (cardiac condition) and age (OR 2.6, 95% CI 1.46-4.71, p<0.001). Ketamine was used in 27% of TIs, more often for patients whose indication for TI was unstable hemodynamics (39% vs. 25%, p<0.001). Ketamine use was not associated with significantly lower incidence of hypotension when compared with other regimens without ketamine (incidence of new hypotension: 8% vs. 14%, p=0.1). Conclusions: A variety of TI induction medications are used in critically ill children. For children intubated in the PICU, 1) Vagolytic use was common but NOT associated with lower incidence of bradycardia even when controlling for diagnosis and age. 2) Ketamine was used more commonly than other sedatives for patients with hemodynamic instability, but was NOT associated with reduced incidence of new hypotension.

Hypothermia in Comatose Survivors From Out-of-Hospital Cardiac Arrest

Background— It is recommended that comatose survivors of out-of-hospital cardiac arrest should be cooled to 32° to 34°C for 12 to 24 hours. However, the optimal level of cooling is unknown. The aim of this pilot study was to obtain initial data on the effect of different levels of hypothermia. We hypothesized that deeper temperatures will be associated with better survival and neurological outcome. Methods and Results— Patients were eligible if they had a witnessed out-of-hospital cardiac arrest from March 2008 to August 2011. Target temperature was randomly assigned to 32°C or 34°C. Enrollment was stratified on the basis of the initial rhythm as shockable or asystole. The target temperature was maintained during 24 hours followed by 12 to 24 hours of controlled rewarming. The primary outcome was survival free from severe dependence (Barthel Index score ≥60 points) at 6 months. Thirty-six patients were enrolled in the trial (26 shockable rhythm, 10 asystole), with 18 assigned to 34°C and 18 to 32°C. Eight of 18 patients in the 32°C group (44.4%) met the primary end point compared with 2 of 18 in the 34°C group (11.1%) (log-rank P =0.12). All patients whose initial rhythm was asystole died before 6 months in both groups. Eight of 13 patients with initial shockable rhythm assigned to 32°C (61.5%) were alive free from severe dependence at 6 months compared with 2 of 13 (15.4%) assigned to 34°C (log-rank P =0.029). The incidence of complications was similar in both groups except for the incidence of clinical seizures, which was lower (1 versus 11; P =0.0002) in patients assigned to 32°C compared with 34°C. On the contrary, there was a trend toward a higher incidence of bradycardia (7 versus 2; P =0.054) in patients assigned to 32°C. Although potassium levels decreased to a greater extent in patients assigned to 32°C, the incidence of hypokalemia was similar in both groups. Conclusions— The findings of this pilot trial suggest that a lower cooling level may be associated with a better outcome in patients surviving out-of-hospital cardiac arrest secondary to a shockable rhythm. The benefits observed here merit further investigation in a larger trial in out-of-hospital cardiac arrest patients with different presenting rhythms. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01155622.

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FTY720 Versus Mycophenolate Mofetil in De Novo Renal Transplantation: Six-Month Results of a Double-Blind Study

FTY720 is a novel immunomodulator that was developed to produce optimal graft protection with improved safety and tolerability. Phase II studies have demonstrated the efficacy of FTY720 up to the doses of 2.5 mg with full-dose cyclosporine (FDC). This multicenter, double-blind, Phase IIb, randomized study evaluated the safety and efficacy of 5 mg FTY720 (n=87; Group 1) vs. 2.5 mg FTY720 (n=90; Group 2) vs. mycophenolate mofetil (MMF; n=94; Group 3) in de novo renal transplant patients receiving FDC and prednisone. The primary efficacy endpoint was the occurrence of treated biopsy-proven acute rejection, graft loss, death, or premature study discontinuation (composite endpoint) within 6 months. The primary endpoint was superior in Group 1 (24%) and statistically noninferior in Group 2 compared to Group 3 (24.1% vs. 29.2% vs. 39.4%; P=0.025 and 0.0039, respectively). FTY720 plus FDC was generally well tolerated, with a similar incidence of adverse events across all groups. FTY720 was associated with higher incidence of bradycardia (Group 1: 26.4%, P=0.0002 and Group 2: 15.6%, P=0.046, vs. Group 3: 6.4%), respiratory disorders (Group 1: 40.2%, not significant [P=NS] and Group 2: 34.4%, P=NS vs. Group 3: 28.7%). One macular edema occurred in Group 2. Lower creatinine clearances were observed with FTY720 versus MMF (Group 1: 52.4 ml/min, P=NS and Group 2: 51.7 ml/min, P=0.039 vs. Group 3: 62.5 ml/min). Although FTY720 with FDC provided adequate protection from acute rejection the safety profile was less favorable for adverse events than current standard immunosuppression in de novo renal transplant patients.

QT interval, heart rate and arterial pressures using propofol, thiopentone or methohexitone for induction of anaesthesia in children

The effects on corrected QT interval (QTc), heart rate and arterial pressure were studied after induction with propofol 1.5, 2 or 2.5 mg.kg-1, thiopentone 5 mg.kg-1 or methohexitone 2 mg.kg-1 in 123 ASA class I or II children undergoing outpatient otolaryngological surgery. Premedication consisted of oral midazolam and atropine. The children were randomly allocated to one of the three propofol groups or to the thiopentone or methohexitone group. After injection of the intravenous anaesthetic, the QTc interval was significantly prolonged after propofol 2.5 mg.kg-1. Thirty seconds after suxamethonium 1.5 mg.kg-1, a significant prolongation of the QTc interval occurred in the thiopentone and propofol 1.5 and 2 mg.kg-1 groups. After intubation, no further prolongation of the QTc interval occurred in any of the groups. Heart rate increased significantly after the barbiturates but not after propofol. Systolic arterial pressure decreased significantly after propofol 1.5 and 2.5 mg.kg-1. In all groups a cardiovascular intubation response occurred. Bradycardia and junctional rhythm occurred in 4% of the children in both barbiturate groups and in 19-29% in the propofol groups. It is concluded that propofol causes prolongation of the QT interval and results in a higher incidence of bradycardia and junctional rhythm than the barbiturates.

ECG changes during cerebral angiography; a comparison of low osmolality contrast media

334 electrocardiographic recordings obtained from 109 patient who underwent cerebral angiography with low osmolality contrast media (CM) were analysed. CM used in this study included meglumine sodium ioxaglate, iopamidol, and iohexol. A tachycardial effect greater than 10% was seen in 8.3% of recordings, while a bradycardial effect greater than 10% was seen in 11.1%. Assessment was based on the type of CM used, age of the patients, usage of atropine sulfate as premedication, and the vessel injected. Patients who were under 19 years of age, and unpremedicated had a significantly higher incidence of bradycardia. On the other hand, there was no significant difference of the incidence of electrocardiographic abnormality between the three CM, and between two injected vessel groups. We have also analysed the incidence of generalized adverse effect. There was no serious complication, however, 11.9% of the patients who underwent cerebral angiography with ioxaglate developed urticaria and this was significantly higher incidence than in the other two CM groups.

A cardioplegia oxigenada na proteção miocárdica durante a cirurgia cardíaca: estudo clínico e enzimático

A cardioplegia tem sido reconhecida como um fator muito importante na proteção oo miocárdio. Sabe-se que, mesmo a 15ºC, o coração consome oxigênio. Testes in vitro demonstraram que a cardioplegia cristalóide libera mais oxigênio que a sangüínea. Neste estudo, foram analisadas as variações hemodinâmicas, eletrocardiográficas e enzimáticas em 26 pacientes divididos em 2 grupos, nos quais a cardiplegia cristalóide de Gomes foi empregada. Grupo I: 12 pacientes (solução não oxigenada); Grupo II: 14 pacientes (solução oxigenada). A avaliação dos pacientes incluiu a recuperação hemodinâmica após a parada cardíaca, o uso de drogas vasoativas, o ritmo e o aspecto do eletrocardiograma (ECG), a freqüência cardíaca (FC), a pressão arterial média (PAM), a pressão venosa central (PVC) e as enzimas TGO e CPK-MB. Estes parâmetros foram medidos nos seguintes tempos: antes, logo após a cirurgia e após 6, 12, 24, 48 e 72 horas de pós-operatório. Os resultados demonstraram que a recuperação hemodinâmica foi similar em ambos os grupos. O uso de drogas vasoativas foi maior no Grupo II. No ECG, observou-se mais bradicardia e fibrilação ventricular no Grupo II do que no Grupo I. A freqüência cardíaca, a pressão arterial média e a pressão venosa central não mostraram diferença significativa em ambos os grupos. As enzimas TGD e CPK-MB mostraram elevação mais acentuada no Grupo I do que no II e essa diferença foi significativa (P < 0,01). Em conclusão, os dados sugerem que houve comportamento semelhante em ambas as soluções, quanto à recuperação hemodinâmica e a parâmetros vitais. Observou-se uma incidência maior de bradicardia no Grupo II, provavelmente relacionada à maior duração da parada cardíaca, com maior número de infusões de solução cardioplégica. A variação das enzimas sugere que a solução oxigenada foi mais efetiva do que a não oxigenada, para a preservação do miocárdio.

Increased afferent vagal responses produced by epicardial application of nicotine on the canine posterior left ventricle

Vagally mediated vasodepressor reflexes are observed in dogs and patients with acute myocardial ischemia or infarction and may be related to the Bezold-Jarisch reflex. To test whether nicotine and bradykinin produced site-specific vagal vasodepressor and sympathetic vasopressor responses, respectively, we compared blood pressure and heart rate responses to these drugs applied topically at six epicardial sites of the canine left ventricle: midanterior, apical anterior, midlateral, apical lateral, midposterior, and apical posterior left ventricle. In α-chloralose-anesthetized dogs with open chests a felt pad soaked in bradykinin (25 μg) or nicotine (50 μg) was applied to the test sites. Previous studies indicated that epicardial application of these drugs elicited a sympathetically mediated pressor response and a vagally mediated depressor response, respectively. Vasopressor response to bradykinin did not differ among six test sites in 10 dogs. However, vasodepressor response to nicotine was greater in the midposterior left ventricular epicardium than at other test sites in 16 dogs. A hypertensive response after the initial hypotensive response to nicotine was observed in the midanterior left ventricle and not in any other site. These data indicate that vagal vasodepressor responses to epicardial nicotine are greater in the canine midposterior left ventricle and are compatible with the higher incidence of bradycardia or hypotension during acute inferoposterior myocardial infarction in patients. Sympathetic vasopressor responses to epicardial bradykinin are not site specific. Half of the dogs showed no response to bradykinin or nicotine.