Neurohormonal Profile Before and After β-Blockade in Patients with Neurocardiogenic Syncope

Our objective was to evaluate the effects of beta-blockers on the neurohormonal profile, particularly vasopressin (VP) release, in vasovagal syncope and to gain further insight on the pathophysiology of this syndrome. Patients (< or =75 years) with no cardiovascular, neurological disorders, or contraindications to the use of isoproterenol or beta-blockers and being explored for unexplained syncope were included. An 80 degrees HUT was performed under identical conditions. After a 25-min period of passive tilt, isoproterenol was infused at a rate of 1-5 microg/mn if required. Two groups matched for age and sex were considered: a HUT-positive and a HUT-negative group. The HUT-positive group was then given beta-blockers, subsequently reassessed, and divided into two subgroups: alpha beta-blocker nonresponder group and a beta-blocker responder group. Blood samples for assays of norepinephrine (NE), epinephrine (E), and VP were taken at baseline and the end of the procedure. In all, 44 subjects entered the study, 22 in each group. The HUT-positive group exhibited an obvious lesser increase in plasma NE and a clear-cut rise in plasma E and VP compared to the HUT-negative group (P < 0.05). Even though no patient in the HUT-positive group reported recurrent symptoms under treatment, the second HUT could distinguish two subgroups: a beta-blocker nonresponder group (n = 12) whose HUT remained positive and a beta-blocker responder group (n = 10) whose HUT was normalized. The time course of plasma E and VP during the second HUT was similar to that for the HUT-positive and HUT-negative groups. In conclusion, the efficacy of beta-blockers is associated not only with a reduction of the sympathoadrenal stimulation seen in vasovagal syncope but also with a lower release of VP suggesting that low-pressure baroreceptors might be involved in VP release.     

Heart Rate Variability During Head-up Tilt Testing in Patients with Suspected Neurally Mediated Syncope

The relation between heart rate variability (HRV) and outcome of head-up tilt testing (HUT) in patients with neurally mediated syncope (NMS) was studied in 30 patients with presumed NMS (33 ± 13 years) and in 11 age-matched controls. After 15 minutes of baseline supine observation, patients were tilted to 60± for 45 minutes or until syncope occurred. HRV parameters included RR intervals, standard deviation of normal-to-normal RR intervals (SDNN), and root mean square successive differences (RMSSD). HRV analysis was performed during 5-minute intervals in the supine position immediately after onset of HUT and before syncope or after 30–35 minutes of tilt in patients without syncope. Syncope occurred after a mean tilt duration of 32 minutes in 14 (47%) of 30 patients with presumed NMS, whereas all controls had an uneventful HUT. In the supine position, RR intervals and RMSSD were comparable among HUT-positive patients, HUT-negative patients, and controls (RR intervals: 799 ± 92, 854 ± 137, and 818 ± 128 ms, P = NS; RMSSD: 43 ± 40, 36 ± 34, and 53 ± 42 ms, P = NS). Baseline SDNN was also comparable in HUT-positive patients versus HUT-negative patients with presumed NMS (50 ± 26 vs 52 ± 20 ms, P = NS). Within 5 minutes preceding syncope or after 30–35 minutes of tilt, RR intervals and RMSSD were shorter in HUT-positive patients compared to HUT-negative patients, or to controls (RR intervals: 606 ± 86 vs 710 ± 117 and 739 ± 123 ms, P < 0.05; RMSSD: 12 ± 5 vs 23 ± 19 and 40 ± 32 ms, P < 0.05). Thus, HRV analysis in the baseline supine position was not a predictor of HUT outcome in patients with suspected NMS. Syncope during HUT seemed to be preceded by increased sympathetic activity manifested by an increase in heart rate and by a decreased parasympathetic tone manifested by a decrease in RMSSD measured for 5 minutes before the event, in comparison with HUT-negative patients and with controls.     

Assessment of autonomic activity during daily life of patients with head-up tilt-induced prolonged asystole

Autonomic activity is important in the pathophysiology of neurally mediated syncope (NMS) patients diagnosed by the head-up tilt (HUT) test, and prolonged systole induced by HUT is associated with a malignant vasovagal syndrome. This study investigated whether or not daily autonomic activity evaluated by heart rate variability (HRV) assessed through 24-hour ambulatory ECG monitoring was augumented in HUT-induced asystole (AS; >30 s) and whether or not HRV differed between NMS patients with and without AS. Ambulatory ECG monitoring was performed in 176 patients with suspected NMS and in 62 age-matched healthy control subjects (C group, age: 36±13 yr), with HRV time and frequency domain indices measured within 48 hours of HUT. Six patients displayed prolonged AS (PAS group, age: 33±12 yr), and 109 patients had positive HUT (P group, age: 29±17 yr), while 61 patients had negative HUT (N group, age: 40±18 yr). Several HRV indices in the P group were higher than those in the N and C groups. However, HRV indices did not differ between the P group and the PAS group. It is concluded that impairment of autonomic activity specifically related to orthostatic stress could be important in the pathophysiology of HUT-induced prolonged asystole, while impairment of autonomic activity in daily life is not as important in NMS patients with HUT-induced prolonged asystole.     

A Sensor-based Evaluation of Heart Contractility in Patients with Head-up Tilt-induced Syncope

Studies using the head-up tilt test (HUT) suggest that a reflex increase in sympathetic activity resulting in vigorous myocardial contractions precedes neurally-mediated syncope (NMS), The aim of this study wax to evaluate heart contractility changes during positive HUT. Ten patients with recurrent NMS and positive HUT were investigated. Before HUT we temporarily placed a standard right ventricular pacing electrode incorporating in its tip a recently developed microaccelerometer (Sorin Biomedica, Italy) that measures the peak endocardial acceleration (PEA) during the isovolumetric phase as an index of heart contractility. PEA potential amplitude, heart rate and mean blood pressure were continuously studied during HUT. Syncope occurred 16.7 ± 10.3 min after 60° till, either at baseline (8 patients) or after sublingual nitrate administration (2 patients). PEA value was stable at 0.62 ± 0.34 (1G = 9.8 m/sec²) during the supine phase. It slightly increased to 0.72 ± 0.44 G (p = NS) during the first minutes of 60° tilt and then remained unchanged until a further increase of 71 ± 79% (range 10 to 266 %) as compared to tilt value (p = 0.004) at 2.8 ± 2.4 min (range 0.25 to 6.5 min) before the syncope in 9 patients. The latter increase was not observed in the patient with dilated cardiomyopathy. In conclusion, a significant increase in heart contractility was observed in 9 patients in the minutes preceding HUT-induced NMS. These changes might be used for driving a rate adaptive pacemaker when cardiac pacing is indicated to prevent NMS.     

Hemodynamic Parameters and Heart Rate Variability during a Tilt Test in Relation to Gene Polymorphism of Renin‐Angiotensin and Serotonin System

Purpose: The aim of the study was to evaluate the renin‐angiotensin system and serotonin transporter gene polymorphisms in relation to hemodynamic parameters and heart rate variability during a head‐up tilt test (HUT) in patients with vasovagal syncope. Methods: DNA was collected from 191 patients (mean age 44 ± 18 years, 61 men, 130 women). The following gene polymorphisms were determined in genomic DNA: angiotensin‐converting enzyme insertion/deletion polymorphism (I/D ACE), angiotensinogen gene polymorphism (M 235), angiotensin II receptor type 1 (ATR1) polymorphism (A 11666C), and polymorphism of serotonin transporter gene (5HTTLPR). Heart rate variability during HUT was assessed in 5‐minute intervals by low frequency, high frequency, standard deviation of the normal‐to‐normal (SDNN), and root mean square successive difference parameters. Results: AA genotype of A 1166C polymorphism was associated with lower minimal systolic blood pressure (SBP) and diastolic blood pressure (DBP) during HUT compared with other genotypes (minimal SBP: AA 59.6 ± 21,8, AC 79.9 ± 22.7, CC 65.4 ± 22.7 mmHg, P = 0.007), (minimal DBP: AA 36.4 ± 22.7, AC 52.3 ± 22.9, CC 45.4 ± 19.5 mmHg, P = 0.007). AA genotype was also associated with higher SDNN compared to other genotypes in the early phase of HUT (SDNN in 5 minutes of tilt: AA 59.7 ± 24.6, AC 50.6 ± 20.6, CC 46.0 ± 13.2, P = 0.01) and at syncope occurrence (SDNN: AA 71.0 ± 20.9, AC 58.2 ± 17.9, CC 58 ± 10, P = 0.04) Conclusion: AA genotype of A 1166C polymorphism in the ATR1 gene may be associated with hypotension and decline in sympathetic tone during HUT. Its role in genetic predisposition to vasovagal syncope cannot be excluded.     

Myocardial contractility and cardiac filling measured by impedance cardiography in patients with nitroglycerine-induced vasovagal syncope

OBJECTIVE: Increased myocardial contractility and inadequate cardiac filling leading to activation of the Bezold-Jarisch reflex were proposed as possible triggering mechanisms of vasovagal syncope (VVS). In the present study noninvasive hemodynamic measurements were performed in order to examine the role of myocardial contractility and cardiac filling in pathogenesis of VVS. METHODS: Hemodynamic parameters were measured during head-up tilt test (HUT) by impedance cardiography in 46 patients with unexplained syncope. Myocardial contractility was measured as index of contractility (IC), acceleration index (ACI), and ejection fraction (EF). Afterload was measured as systemic vascular resistance index (SVRI) and preload was expressed as end-diastolic index (EDI). Serial measurements were done 1 minute before HUT, during HUT at 1-minute intervals, and 1 minute after completion of HUT. RESULTS: HUT was positive in 30 patients (10 men, 20 women, mean age 36 +/- 16 years) and negative in 16 patients (8 men, 8 women, mean age 31 +/- 14 years). No significant differences were observed between HUT(+) and HUT(-) groups in hemodynamic parameters at supine rest and during HUT until the development of syncope. SVRI was lower in HUT(+) than in HUT(-) group at syncope (122.7 + 66.3 vs 185.6 + 51.4 dyn sec cm(-5)/m2, P = 0.002) and after syncope (117.0 + 61.1 vs 198.0 + 95.7 dyn sec cm(-5)/m2, P = 0.007). ACI, IC, EF, and EDI did not differ between groups at syncope. After syncope EF was higher in HUT(+) group compared to HUT(-) group (59.2 + 6.1 vs 52.7 + 9.4%, P = 0.02). CONCLUSION: The role of increased myocardial contractility and decreased cardiac filling is not confirmed in the present study.     

Transcranial Doppler ultrasonographic evaluation of cerebral circulation during passive tilting in patients with Parkinson's disease

PURPOSE: To assess the effects of the tilt test on cerebral blood flow velocity (CBFV), blood pressure, and heart rate in patients with Parkinson's disease (PD) without symptomatic orthostatic dysautonomia. METHODS: Thirty patients with idiopathic PD and 15 healthy controls were included. Mean middle cerebral artery blood flow velocity (CBFV) was recorded with transcranial Doppler sonography, while systolic (SBP), diastolic (DBP), and mean (MBP) blood pressure and heart rate were measured in the supine position and after passive tilting. RESULTS: There was no difference in resting SBP, DBP, or MBP between patients and controls. CBFV was lower at rest in patients than in controls and dropped significantly and similarly after tilting in both groups. SBP decreased in patients during the first 5 minutes of tilting (p < 0.05), whereas it increased progressively after the first minute in controls. In patients, DBP decreased slightly and MBP dropped during the first 2 minutes, then increased. Baseline heart rate was higher in patients than in controls (p < 0.05) and increased in both groups during tilting. CONCLUSION: Our results suggest that cardiovascular responses to tilting are delayed in PD patients and that subclinical autonomic dysfunction may be present even in the absence of symptomatic orthostatic dysautonomia.     

A randomized and controlled pilot trial of beta-blockers for the treatment of recurrent syncope in patients with a positive or negative response to head-up tilt test

The aim of this study was to assess the efficacy of lipophilic beta-blockers in preventing recurrent neurocardiogenic syncope and the value of head-up tilt test (HUT) in predicting response to therapy. The efficacy of beta-blockers in recurrent syncope is controversial. The value of HUT in predicting efficacy of therapy has not been investigated. Fifty-six patients (44+/-18 years, 36 women) with recurrent syncope (> 1 event in the last 6 months) of suspected neurocardiogenic origin were included in the study. Independent of the response to HUT, patients were randomized to receive metoprolol or propanolol at the maximal tolerated dose (28 patients, group A, 86+/-23 vs 98+/-29 mg/d) or no pharmacological therapy (28 patients, group B). The primary endpoint was the first recurrence of syncope. During the 1-year of follow-up, 20 patients of group A and 8 of group B had no recurrence. In group A, of 20 patients without recurrences 12 had a positive and 8 a negative HUT result while of 8 patients with recurrences 5 had a positive and 3 a negative response to HUT. In the group B, of 20 patients with recurrences 10 had a positive and 10 a negative HUT result while of 8 patients without recurrences 4 had a positive and 4 a negative response to HUT. In a multivariate Cox-regression analysis, medical therapy was the only independent factor for predicting recurrence of syncope (P = 0.004); HUT had no influence in this regard (P = 0.773). In conclusion, lipophilic beta-blockers appear efficacious in preventing recurrent syncope of suspected neurocardiogenic origin. The efficacy of therapy seems to be not predicted by HUT.     

A "Dysautonomic" Head-Up Tilt Test Pattern in Elderly Patients with Neurocardiogenic Syncope

The characteristics of neurocardiogenic syncope (NCS) in elderly patients remain unclear. We compared the hemodynamic profiles of young and older patients with consecutive and positive head-up tilt tests (HUT). Continuous, noninvasive, and reliable monitoring of arterial pressure (AP) and heart rate (HR) was done throughout 46 consecutive positive HUTs of symptomatic patients. The population (12-82 years old) was divided into two groups: younger patients, Y (n = 25, < or = 65 years), and older patients, O (n = 21). Changes in AP and HR after the first minute of tilting, during the stable orthostatic phase and during syncope were compared. Except for systolic pressure, baseline hemodynamic parameters were similar in Y and O. No difference appeared in the mean time elapsed before syncope (19+/-9 vs 22+/-2 min). Asymptomatic hypotension was observed, only in O, 1 minute after tilting, followed by a progressive fall in the mean AP before syncope (0+/-0.9 vs -1+/-0.7 mmHg/min) without HR increase (0.7+/-1 vs 0+/-0.6 beats/min). This pressure slope was strongly related to age (r = 0.54, P < 0.001). Hemodynamic recording during HUT identifies a dysautonomic pattern in elderly patients with NCS and the abnormal AP/HR responses to orthostasis may be a feature specific to this population. Although the central mechanism of NCS is common to all ages, the age-related characteristics of the trigger event may indicate the need for specific management at different ages.     

The role of tilt training in preventing recurrent syncope in patients with vasovagal syncope: a prospective and randomized study

Background: Recurrent vasovagal syncope (VVS) can be a severely disabling disorder that may lead to an important deterioration of quality of life because of the severity and recurrence of episodes. This study sought to investigate the effectiveness of repeated orthostatic self-training in preventing syncope in patients with recurrent VVS.
Methods: Eighty-two consecutive patients (mean age 41 ± 4 years, 37 males) with recurrent VVS episodes and positive head-up tilt testing (HUT) were enrolled in this study. The patients were then randomized (1:1) to conventional therapy or conventional therapy plus additional tilt training sessions. The patients were followed for spontaneous syncope for one year. Primary end-points were the recurrence of syncope, the number of episodes, and the interval of time to the first recurrence.
Results: There were no significant differences of baseline clinical characteristics and parameters of HUT between the tilt training and control groups. The patients had 4 ± 2/year syncopal episodes prior to the HUT. The mean follow-up after randomization was 12 ± 2 months. Spontaneous syncope recurrence during follow-up was 56% (23 patients) versus 37% (15 patients) in the control and tilt training groups, respectively (P = 0.1). Time to first recurrence was also similar in both groups (70 ± 20 days vs 50 ± 15 days, P = 0.09). The frequency of recurrent syncopes was similar in all types of VVSs while the rate of episodes was significantly higher in control group in patients with vasodepressor type during follow-up period (32% vs 10%, P = 0.04). The mean number of recurrent syncope episodes was also similar in both groups (3 ± 1 vs 2 ± 1, P = 0.4).
Conclusions: Tilt training was unable to influence the spontaneous syncope recurrence for recurrent VVS except for vasodepressor type.     

Tolerance to Lower Body Negative Pressure Exposure: Comparison Between Patients with Neurocardiogenic Syncope and Controls

Lower body negative pressure exposure (LBNPE) produces hemodynamic modifications similar to those produced by head-up tilt test (HUT). Patients with vasovagal syncope are more susceptible to HUT than healthy persons. The supine position during LBNPE would facilitate the simultaneous performance of complementary methods. The aim of this study was to compare tolerance to LBNPE between a group of patients with vasovagal syncope and a group of healthy volunteers. Eleven patients with vasovagal syncope and positive HUT and 13 healthy volunteers without prior history of syncope and negative HUT were included. The following protocol was used: −10 mmHg, 1 minute; −20 mmHg, 1 minute; −30 mmHg, 3 minutes, and −40, −50, −60, and −70 mmHg, 5 minutes for each stage. Tolerance was expressed as: maximum tolerated negative pressure (Max NP), maximum tolerated time (Max T), and Σ P × T, where P = pressure and T = time. Syncope or presyncope during the test was considered positive LBNPE. LBNPE was positive at −50 or −60 mmHg in 8 of 11 patients (73%). One healthy volunteer had presyncope after 5 minutes at −70 mmHg. Tolerance, as expressed by any of the three parameters, was significantly higher for the healthy volunteers (Max NP: −59.1 ± 7.9 vs −70, P < 0.01; Max T: 19.1 ± 4.2 vs 24.4 ± 0.3, P < 0.01; Σ P × T: 836.3 ± 269.5 vs 1214.6 ± 18, P < 0.01). We conclude that patients with neurocardiogenic syncope have a significantly lower tolerance to LBNPE than subjects with no previous history of syncope.     

Haemodynamic response to peripheral venous congestion in patients with unexplained recurrent syncope

In patients with recurrent unexplained syncope, exaggerated peripheral venous pooling and impaired circulatory adjustment is thought to contribute to the outcome of a head-up tilt (HUT) test. The present study investigated the role of leg volume changes during venous congestion in the haemodynamic response of patients with recurrent unexplained syncope and the ability to predict the outcome of a HUT test. Changes in calf volume (strain gauge plethysmography), heart rate and arterial blood pressure were recorded in 60 patients with history of unexplained syncope (without postural tachycardia symptom) during venous congestion provoked by pneumatic thigh cuffs while supine at rest and during the initial 10 min of a 45 min 70 degrees HUT test. Twenty-seven patients [age (mean+/-S.D.), 39+/-16 years] exhibited symptoms [HUT(+)] and 33 patients (45+/-14 years) were asymptomatic [HUT(-)]. During venous congestion, mean+/-S.E.M. calf volume increased in both groups [HUT(-), 4.5+/-0.2; HUT(+), 4.8+/-0.4 ml x 100 ml(-1), not significant), but significantly less during head-upright tilt [HUT(-), 3.3+/-0.2, P <0.01; HUT(+), 2.6+/-0.3 ml x 100 ml(-1), P <0.001] without differences between the groups. During venous congestion, arterial pressure increased significantly in asymptomatic HUT(-) patients, but not in the HUT(+) patients. Calf volume changes did not correlate with a symptomatic outcome to a 70 degrees HUT. The lack of exaggerated venous pooling during venous congestion and the inability of calf volume changes to predict a positive HUT suggest that excessive venous pooling does not contribute to the outcome of HUT. Attenuated changes in arterial pressure during venous congestion while supine suggest impaired adjustment of peripheral resistance to leg venous occlusion.     

Predictors of Positive Head-Up Tilt Test in Patients with Suspected Neurocardiogenic Syncope or Presyncope

OH, J.H., et al .: Predictors of Positive Head-Up Tilt Test in Patients with Suspected Neurocardiogenic Syncope or Presyncope. Neurocardiogenic syncope is the most common cause of syncope in patients who present in outpatient clinics. Head-up tilt test (HUT) has been widely used to diagnose neurocardiogenic syncope. However, the HUT does not always produce a positive response in patients with suspected neurocardiogenic syncope. The aim of the present study was to assess the clinical history and characteristics of patients with suspected neurocardiogenic syncope or presyncope who undertook HUT, and to identify prognostic factors of a positive HUT response. During the first phase of HUT, patients were tilted to a 70-degree angle for 30 minutes. If the first phase produced a negative response, the second phase was subsequently performed involving intravenous isoproterenol administration. Of 711 patients, 423 (59.5%) patients showed a positive HUT response. In contrast to previous studies, this study showed that the vasodepressive type (76.6%) was the most common pattern of positive response, and that the rate of positive response during the first phase was low (7.1%). By multivariate analysis, the occurrence of junctional rhythm was found to be a predictor of an impending positive response in HUT   (P < 0.001)   . The shorter time interval between the last episode and HUT was also a predictor of positive response   (P = 0.0015)   . Younger age   (P = 0.0003)   and a history of physical injury during a syncopal episode   (P = 0.019)   were found to be associated with a positive response in the first phase of HUT. (PACE 2003; 26[Pt. I]:593–598)     

The effects of lower-extremity functional electric stimulation on the orthostatic responses of people with tetraplegia

OBJECTIVE: To determine whether application of functional electric stimulation (FES) to lower-limb muscles during postural tilting improves orthostatic tolerance in people with tetraplegia. DESIGN: A crossover design. SETTING: A rehabilitation hospital. PARTICIPANTS: Sixteen acute and chronic subjects with tetraplegia (15 men, 1 woman) with complete motor function loss at the C3-7 levels were recruited. Time since injury ranged from 2 to 324 months (mean, 118.9+/-104.2 mo). INTERVENTION: Subjects were tested on a progressive head-up tilting maneuver with and without the application of FES at 0 degrees , 15 degrees , 30 degrees , 45 degrees , 60 degrees , 75 degrees , and 90 degrees continuously for up to 1 hour. FES was administered to 4 muscle groups including the quadriceps, hamstrings, tibialis anterior, and gastrocnemius muscles bilaterally at an intensity that provided a strong, visible, and palpable contraction. This was to produce a muscle pumping mechanism during the tilting maneuver. MAIN OUTCOME MEASURES: Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, perceived presyncope score, and the overall duration of orthostatic tolerance, that is, the time that subjects could tolerate the tilting maneuver without developing severe hypotension or other intolerance symptoms. RESULTS: When the tilt angle was increased, the subjects' SBP and DBP tended to decrease, whereas the heart rate tended to increase in both testing conditions. Adding FES to tilting significantly attenuated the drop in SBP by 3.7+/-1.1 mmHg (P = .005), the drop in DBP by 2.3+/-0.9 mmHg (P = .018), and the increase in heart rate by 1.0+/-0.5 beats/min (P = .039) for every 15 degrees increment in the angle of the tilt. FES increased the overall mean standing time by 14.3+/-3.9 min (P = .003). CONCLUSIONS: An FES-induced leg muscle contraction is an effective adjunct treatment to delay orthostatic hypotension caused by tilting; it allows people with tetraplegia to stand up more frequently and for longer durations.     

Impairment of Coronary Microvascular Function in Patients with Neurally Mediated Syncope

CHEN, J.-W., et al .: Impairment of Coronary Microvascular Function in Patients with Neurally Mediated Syncope. Recent evidence suggests that myocardial ischemia may occur in patients with neurally mediated syncope and normal coronary angiograms. This study was conducted to evaluate if coronary microvascular function is impaired in such patients. Coronary hemodynamic studies and head-up tilt table tests (HUTs) were performed on 30 consecutive patients with normal coronary angiograms and recurrent syncope. Another ten subjects with atypical chest pain and no evidence of myocardial ischemia or syncope served as a control. Great cardiac vein flow (GCVF) and coronary sinus flow (CSF) were measured by the thermodilution method at baseline and after dipyridamole infusion (0.56 mg/kg IV for 4 minutes). Coronary flow reserve (CFR), derived from CSF and GCVF, was significantly lower in the 15 patients with positive HUT than in the other 15 patients with negative HUT (   1.75 ± 0.48   vs   2.64 ± 0.8   ,   P < 0.01   and   2.29 ± 0.45   vs   3.07 ± 0.63   ,   P < 0.01   , respectively). Ischemic-like ECG was noted during treadmill exercise test in 40% of the former and in 7% of the latter group   (P = 0.01)   . There was no significant difference in CFR between patients with negative HUT and control subjects. Coronary microvascular function was impaired in syncopal patients with positive HUT and relatively preserved in those with negative HUT, suggesting the possible linkage between coronary microvascular dysfunction and the development of neurally mediated syncope. (PACE 2003; 26[Pt. I]:605–612)     

依托咪酯和咪唑安定对不停跳冠状动脉旁路搭桥手术气管插管期间心率和血压影响的比较(英文)

Objective To compare the effect of etomidate and midazolam on heart rate and blood pressure during tracheal intubation in off-pump coronary artery bypass graft. Methods Sixty patients scheduled for coronary artery bypass graft surgery without cardiopulmonary bypass shunt were randomly and double-blindly divided into etomidate group (Group E,n=30) and midazolam group (Group M,n=30) based on the anesthetic used for induction.Electrocardiogram,systolic blood pressure (SBP),diastolic blood pressure (DBP),heart rate (HR) and pulse oximetry saturation (SpO2) were measured and recorded continuously,as well as the value of rate-pressure product (RPP).The time used for tracheal intubation was also recorded.Results In Group M,compared with pre-tracheal intubation,the SBP and DBP of all patients decreased remarkably at the beginning of tracheal intubation (P<0.05).At 1 minute post-trachealintubation,the SBP,DBP and HR increased remarkably (P<0.01);meanwhile,the values of RPP were increased significantly than those at the beginning of tracheal intubation and pre-tracheal intubation (P<0.01).Compared with the values in Group E,at the beginning of tracheal intubation,the values of SBP and DBP in Group M were significantly decreased (P<0.05 and P<0.01,respectively),while the values of SBP,DBP and RPP at 1 minute after tracheal intubation were significantly increased (P<0.05 and P<0.01,respectively). Conclusions Compared with midazolam,etomidate used in anesthetic induction for coronary artery bypass graft surgery without cardiopulmonary bypass shunt may more effectively alleviate the cardiovascular responses to tracheal intubation.     

Low Dose Disopyramide Often Fails to Prevent Neurogenic Syncope During Head-Up Tilt Testing

Low dose disopyramide has been used to prevent neurally-mediated syncope during head-up tilt testing but a correlation between blood levels and efficacy has not been described. We measured disopyramide levels in 15 patients with recurrent syncope and positive 70° head-up tilt tests who underwent one or more repeat tests on the drug. There were 9 males and 6 females, age range 15–78 years. Fourteen of the 15 patients had structurally normal hearts. The daily disopyramide dose was 645 ± 165 mg (mean ± SD). Patients developed syncope during 9 tests and had no syncope during 12 tests. The mean disopyramide level in patients with positive tests was significantly lower than the level in patients with negative tests (2.4 ± 0.15 μ/mL vs 3.2 ± 0.22 μ/mL, P = 0.018). Six patients were tested twice on different disopyramide doses. Five of these six patients had syncope during head-up tilt testing on the lower dose and negative tests on the higher dose (disopyramide levels 2.2 μ 0.17 μ/mL vs 3.2 μ0.17 fi/mL, P = 0.004). Thus, disopyramide is effective in preventing neurogenic syncope during head-up tilt testing, but higher blood levels are often necessary for efficacy. In a given patient, failure to respond to low dose disopyramide does not preclude success on higher doses.     

不同剂量右美托咪定对妊高征剖宫产患者血流动力学的影响

目的探讨不同剂量右美托咪定对妊高征剖宫产患者血流动力学的影响。方法将本院行择期剖宫产术的325例妊高征产妇分为对照组与A、B、C、D组,每组各65例产妇。对照组仅接受基础麻醉,A、B、C、D组在基础麻醉的基础上再分别静脉泵入0.1、0.2、0.3、0.4μg/(kg·h)试验量与维持量右美托咪定直至手术结束。分别记录所有产妇硬膜外给药前(T_0)、切皮时(T_1)、胎儿娩出时(T_2)、手术结束时(T_3)的收缩压(SBP)、舒张压(DBP)、心率(HR)等指标。结果 5组4个时间点SBP、DBP、HR相比差异均有统计学意义(P0.05);T_0时,5组的SBP、DBP、HR均显著高于本组T_1、T_2、T_3时(P0.05);T_1时的SBP、DBP、HR均显著高于本组T_2、T_3时(P0.05),其T_2时的SBP、DBP、HR均显著高于本组T_3时(P0.05)。T_0时,5组研究对象SBP、DBP、HR相比差异均无统计学意义(P0.05);T_1~T_3时,5组研究对象SBP、DBP、HR相比差异均有统计学意义(P0.05),D组的SBP、DBP、HR均显著低于A、B、C组,对照组(P0.05),C组的SBP、DBP、HR均显著低于A、B组,对照组(P0.05),B组的SBP、DBP、HR均显著低于A组、对照组(P0.05),A组与对照组之间SBP、DBP、HR相比差异均无统计学意义(P0.05)。结论在妊高征剖宫产术中,右美托咪定剂量为0.4μg/(kg·h)时具有较好的稳定血流动力学作用,且随着剂量的增加,其效果越明显。     

Fixed combinations of delapril plus indapamide vs fosinopril plus hydrochlorothiazide in mild to moderate essential hypertension

This 12-week randomized, parallel-group, multicenter study compared fixed combinations of delapril (D) 30 mg plus indapamide (I) 2.5 mg and fosinopril (F) 20 mg plus hydrochlorothiazide (H) 12.5 mg in 171 adult patients with mild to moderate essential hypertension. After a 2-week placebo run-in, sitting and standing systolic (SBP) and diastolic blood pressure (DBP) was measured by conventional sphygmomanometry. The primary efficacy endpoint was the percentage of normalized (sitting DBP ≤90 mm Hg) and responder (sitting DBP reduction of ≥10 mm Hg or DBP ≤90 mm Hg) patients. Treatment effects were analyzed in the intention-to-treat (ITT; n = 171) and the per-protocol (PP; n = 167) populations. The percentage of normalized and responder patients did not differ significantly between the D + I (87.4% and 92%) and the F + H (81% and 86.9%) ITT groups. Similar results were seen in the PP population. In ITT and PP patients, sitting and standing SBP and DBP values were comparable at baseline in the two groups and were significantly (P<.01) and similarly reduced at weeks 4, 8, and 12. Neither treatment induced reflex tachycardia, and both regimens were well tolerated. Four patients in the F + H group dropped out because of adverse events. In this study, the efficacy and safety of D + I were comparable to those of F + H in patients with mild to moderate essential hypertension.     

硬膜外麻醉与全身麻醉下妇科腹腔镜手术病人的血液动力学与血糖变化

目的观察比较硬膜外麻醉和全身麻醉用于妇科腹腔镜手术时患者围麻醉期血流动力学及血糖的变化。方法60例妇科腹腔镜手术病人均分为两组:硬膜外麻醉组(EA组)和全身麻醉组(GA组)。分别于麻醉前、腹压达12mmHg后1min和30min、术毕四个时点监测HR、SBP、DBP、SpO2的变化,并于上述时点测血糖(BS)变化。结果两组手术前后HR无明显变化,在气腹1minEA组HR高于GA组(P<0.01);EA组SBP在气腹30min和术毕均低于麻醉前水平(P<0.05);GA组在气腹后DBP和SBP明显高于麻醉前(P<0.01和P<0.05),DBP直到术毕仍高于麻醉前水平(P<0.05);组间血压比较:气腹后和术毕EA组SBP和DBP明显低于GA组(P<0.05或P<0.01),但维持在正常范围;EA组气腹前后BS的变化无统计学意义(P>0.05),而GA组术毕时BS水平明显高于麻醉前(P<0.05)。结论合适阻滞平面的硬膜外麻醉能较好地消除气腹引起的血压升高和应激反应。