Minimal influence of anaesthesia and abdominal surgery on computerized vectorcardiography recordings

Myocardial infarction still represents a major cause of morbidity and mortality following surgical procedures. Continuous computerized on-line vector-ECG has previously been shown to be useful in the detection of myocardial ischaemia, in acute myocardial infarction and unstable angina pectoris and for ischaemia monitoring after PTCA procedures. This method was presently tested for the possible influence of anaesthesia and surgery during cholecystectomy under general anaesthesia (n = 9), and during inguinal hernia repairs using a spinal block (n = 5). The patients had no history, symptoms or signs of ischaemic heart disease. Analyses of vectorcardiographic changes were made in relation to predefined standardized anaesthetic and surgical procedures, all of which potentially could influence the vector-ECG. Three vectorcardiographic trend parameters were studied: QRS-vector difference, ST-vector magnitude and ST-change vector magnitude. The overall vectorcardiographic changes were minimal and smaller than vectorcardiographic changes previously reported during myocardial ischaemia and infarction. Since anaesthetic and surgical procedures per se had only minor effects on the vector ECG recordings, it is concluded that continuous computerized on-line vectorcardiography will not be skewed by these procedures. Hence, vectorcardiography has the potential of becoming a new monitor for the detection of perioperative myocardial ischaemia.     

Dynamic QRS-complex and ST-segment monitoring by continuous vectorcardiography during carotid endarterectomy

Background. Many authors report a high incidence of cardiacevents during carotid endarterectomy. The aim of the presentstudy was to evaluate the usefulness of dynamic continuous on-linevectorcardiography for monitoring the occurrence of myocardialischaemia during carotid endarterectomy. Methods. We studied 21 patients undergoing carotid endarterectomy.Patients underwent general anaesthesia with isoflurane or sevoflurane.The vectorcardiogram was monitored continuously during carotidendarterectomy. Electrodes were placed according to the previouslydescribed lead system and connected to a computerized systemfor on-line vectorcardiography. Two trend variables were recorded:the QRS vector difference, which reflects changes in the shapeof the QRS complex; and the ST vector magnitude, which representsdeflection of the ST segment from the isoelectric level. TheST segment deflection was measured 60 ms after terminationof the QRS complex. Results. Vectorcardiography was successfully recorded in all21 patients. Three patients showed intraoperative vectorcardiogramabnormalities. In one of these three patients, both ST vectormagnitude and QRS vector difference increased after inductionof anaesthesia and ST vector magnitude returned to baselineafter administration of nitroglycerin. In the other two patients,both ST vector magnitude and QRS vector difference graduallyincreased after cross-clamping of the internal carotid arteryand ST vector magnitude returned to baseline after unclamping.QRS vector difference remained elevated for several hours inall three patients. Conclusions. Monitoring ST vector magnitude and QRS vector differenceby vectorcardiography may be useful for identifying myocardialischaemia during carotid endarterectomy. Br J Anaesth 2003; 90: 142–7     

Laparoscopic cholecystectomy: haemodynamic and neuroendocrine responses after pneumoperitoneum and changes in position

We have assessed the potential for myocardial ischaemia during laparoscopic cholecystectomy in 16 otherwise healthy patients. Continuous ambulatory ECG monitoring was commenced 12 h before operation and continued for 24 h after operation. The neuroendocrine stress response was assessed by measuring plasma concentrations of adrenaline and noradrenaline, human growth hormone, cortisol, renin and aldosterone, and prolactin, at specified times during surgery. Acute ST segment changes in the ECG occurred in only two patients. These episodes were independent of creation of pneumoperitoneum and changes in position. Acute intraoperative increases in MAP were noted during insufflation of carbon dioxide and reverse Trendelenburg positioning (P < 0.05). A four-fold increase in plasma concentrations of renin and aldosterone was noted after pneumoperitoneum and reverse Trendelenburg positioning (P > 0.05). There was a linear correlation between changes in plasma renin and aldosterone concentrations and MAP (r = 0.97 and r = 0.85, respectively). Prolactin concentrations increased four-fold after induction of anaesthesia. Cortisol, HGH, adrenaline and noradrenaline concentrations increased after deflation of the pneumoperitoneum. The time profile-concentration changes of increased MAP and renin-aldosterone suggests a cause-effect relationship. Increased intra-abdominal pressure and reverse Trendelenburg positioning may reduce cardiac output and renal blood flow. The early increase in prolactin concentration was probably secondary to the effect of the opioid fentanyl.      

Vectorcardiography is superior to conventional ECG for detection of myocardial injury after coronary surgery

OBJECTIVE: The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of PMI were studied. DESIGN: VCG registrations were obtained from 218 patients undergoing coronary surgery. The spatial QRS vector loop area of each VCG registration was calculated and the loop area before surgery compared with the loop area after surgery. Conventional VCG criteria for myocardial infarction and set values for loop area reduction were related to sustained elevation of plasma troponin-T and clinical course. RESULTS: Both conventional VCG criteria and spatial changes translated better than Q-waves on scalar ECG into elevation of biochemical markers of myocardial injury and impaired clinical course. CONCLUSION: VCG appears superior to conventional ECG as regards detection of myocardial injury in coronary surgery. Computerized programs have facilitated the registration and the interpretation of VCG and this methodology deserves further evaluation in cardiac surgery.     

Continuous vectorcardiography in cardiac surgery: natural course of vector changes and relationship to myocardial oxygen uptake

Continuous vectorcardiography was registered before and during the first 18 hours after cardiac surgery in 53 patients. QRS vector changes (QRS-VD) occurred during the operation, but no further changes were observed postoperatively. The ST vector (ST-VM) increased during the operation, and a further slight increase occurred postoperatively. Perioperative myocardial infarction occurred in three patients. Their ST-VM was higher than the average in patients without myocardial infarction, while QRS-VD did not differ from the average pattern. Twelve other patients were studied in pacemaker-induced moderate tachycardia. QRS-VD increased in proportion to heart-rate changes (rs median = 0.93, p less than 0.01). QRS-VD also correlated with myocardial oxygen uptake (rs median = 0.62, p less than 0.05). The ST-VM responses were not uniform. The data suggest that vectorcardiogram variables can provide information related to myocardial energy metabolism.     

Effects of posture and pneumoperitoneum during anaesthesia on the indices of left ventricular filling

Background. Laparoscopic surgery requires the use of pneumoperitoneum (PP). When combined with positional changes, pneumoperitoneum may cause marked circulatory alterations.
Methods. Eight anaesthetized cardiovascularly healthy patients, scheduled for laparoscopic cholecystectomy, were studied before and during pneumoperitoneum in three different postures (supine, Trendelenburg and reversed Trendelenburg), employing transesophageal echocardiography and pulmonary artery pressure monitoring.
Results. PP significantly increased end-diastolic area (EDA) and pulmonary capillary wedge pressure (PCWP) irrespective of posture. PCWP was significantly influenced by postural changes, whereas EDA was not. Further, changes in EDA and PCWP covaried during the investigation, but showed no linear correlation. Systolic function, measured as end-systolic area (ESA) and fractional area shortening (FAS), was not altered. Diastolic function, as assessed by the velocity rate of the trans-mitral flow during the early filling phase (E) and the atrial contraction (A), showed no change of the E/A ratio, whereas after the induction of PP there was a significant reduction of the E component.
Conclusions. In cardiovascularly healthy patients, the left ventricular volume is increased during pneumoperitoneum. Further, changes in invasive pressure determinations (PCWP) do not correlate linearly with changes in volume indices of left ventricular filling (EDA).     

Assessment of myocardium at risk with computerized vectorcardiography and technetium-99m-sestamibi-single photon emission computed tomography during coronary angioplasty

OBJECTIVE: To compare the myocardium at risk (MAR) as estimated by computerized vectorcardiography (cVCG) with MAR determined by Tc-99m-sestamibi-SPECT using coronary angioplasty as the model for transient transmural ischemia in humans. METHODS AND RESULTS: In 37 patients with stable angina pectoris, cVCG was recorded continuously during coronary angioplasty. The scintigraphic defect was quantified using an automated software program (CEqual). The ST vector magnitude (ST-VM) and the ST change vector magnitude (STC-VM) correlated well with MAR estimated by scintigraphy, ST-VM (r = 0.71, p < 0.001) and STC-VM (r = 0.84, p < 0.001). All patients with STC-VM <50 microV during occlusion had defects of less than 10% of the left ventricle. CONCLUSION: 1) ST-VM and STC-VM give a reasonable useful estimate of MAR size during transient coronary occlusion. 2) STC-VM <50 microV is a reliable limit to identify patients with MAR size less than 10%. 3) ST-VM does not add information to STC-VM with respect to detection of ischemia. 4) The existence of collateral vessels has great impact on both ST-vector changes and scintigraphic imaging of myocardial ischemia.     

Contributions of myocardial ischemia and heart rate to ST segment changes in patients with or without coronary artery disease

Background: ST changes related to ischemia at different heart rates (HRs) have not been well described. We aimed to analyze ST dynamic changes by vectorcardiography (VCG) during pacing-induced HR changes for subjects with proven coronary artery disease (CAD) and without (non-CAD).
Methods: Symptomatic CAD patients scheduled for elective surgery were enrolled along with a non-CAD group. During anesthesia, both groups were placed at multiple ascending levels. VCG ST data, and in particular in ST change vector magnitude (STC-VM) from baseline, along with arterial and great coronary artery vein (GCV) blood samples were collected to determine regional myocardial lactate production.
Results: A total of 35 CAD and 10 non-CAD patients were studied over six incremental 10 beat/min HR increases. STC-VM mean levels increased in the CAD group from 9±5 to 131±37 μV (standard deviation) compared with non-CAD subjects with 8±3–76±34 μV. Myocardial ischemia (lactate production) was noted at higher HRs and the positive predictive value for STC-VM to detect ischemia was 58% with the negative predictive value being 88%. STC-VM at 54 μV showed a sensitivity of 88% and a specificity of 75% for identification of ischemia.
Conclusions: Both HR and ischemia at higher HRs contribute to VCG ST elevation. Established ST ischemia detection concerning HR levels is suboptimal, and further attention to the effects of HR on ST segments is needed to improve electrocardiographic ischemia criteria.     

Vectorcardiography is Superior to Conventional ECG for Detection of Myocardial Injury after Coronary Surgery

Objective - The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of PMI were studied. Design - VCG registrations were obtained from 218 patients undergoing coronary surgery. The spatial QRS vector loop area of each VCG registration was calculated and the loop area before surgery compared with the loop area after surgery. Conventional VCG criteria for myocardial infarction and set values for loop area reduction were related to sustained elevation of plasma troponin-T and clinical course. Results - Both conventional VCG criteria and spatial changes translated better than Q-waves on scalar ECG into elevation of biochemical markers of myocardial injury and impaired clinical course. Conclusion - VCG appears superior to conventional ECG as regards detection of myocardial injury in coronary surgery. Computerized programs have facilitated the registration and the interpretation of VCG and this methodology deserves further evaluation in cardiac surgery.     

Assessment of Myocardium at Risk with Computerized Vectorcardiography and Technetium-99m-Sestamibi-Single Photon Emission Computed Tomography during Coronary Angioplasty

Objective - To compare the myocardium at risk (MAR) as estimated by computerized vectorcardiography (cVCG) with MAR determined by Tc-99m-sestamibi-SPECT using coronary angioplasty as the model for transient transmural ischemia in humans. Methods and results - In 37 patients with stable angina pectoris, cVCG was recorded continuously during coronary angioplasty. The scintigraphic defect was quantified using an automated software program (CEqual). The ST vector magnitude (ST-VM) and the ST change vector magnitude (STC-VM) correlated well with MAR estimated by scintigraphy, ST-VM ( r = 0.71, p < 0.001) and STC-VM ( r = 0.84, p < 0.001). All patients with STC-VM <50 &#119 V during occlusion had defects of less than 10% of the left ventricle. Conclusion - 1) ST-VM and STC-VM give a reasonable useful estimate of MAR size during transient coronary occlusion. 2) STC-VM <50 &#119 V is a reliable limit to identify patients with MAR size less than 10%. 3) ST-VM does not add information to STC-VM with respect to detection of ischemia. 4) The existence of collateral vessels has great impact on both ST-vector changes and scintigraphic imaging of myocardial ischemia.     

Time course of cerebrovascular autoregulation during extreme Trendelenburg position for robotic‐assisted prostatic surgery

Trendelenburg positioning in combination with pneumoperitoneum during robotic‐assisted prostatic surgery possibly impairs cerebrovascular autoregulation. If cerebrovascular autoregulation is disturbed, arterial hypertension might induce cerebral hyperaemia and brain oedema, while low arterial blood pressure can induce cerebral ischaemia. The time course of cerebrovascular autoregulation was investigated during use of the Trendelenburg position and a pneumoperitoneum for robotic‐assisted prostatic surgery using transcranial Doppler ultrasound. Cerebral blood flow velocity was correlated with arterial blood pressure and the autoregulation index (Mx) was calculated. In 23 male patients, Mx was assessed at baseline, after induction of general anaesthesia, during the Trendelenburg position (40–45°), and after repositioning. During the Trendelenburg position, Mx increased over time, indicating an impairment of cerebrovascular autoregulation. After repositioning, Mx recovered to baseline levels. It can be concluded that with longer durations of Trendelenburg position and pneumoperitoneum, cerebrovascular autoregulation deteriorates, and, therefore, blood pressure management should be adapted to avoid cerebral oedema and the duration of Trendelenburg position should be as short as possible.     

Diagnosis of acute myocardial infarction in patients with chronic left bundle-branch block. Standard 12-lead ECG compared to dynamic vectorcardiography

Standard 12-lead electrocardiogram (ECG) criteria were evaluated and compared with dynamic vectorcardiography for diagnosing acute myocardial infarction in 33 patients with chronic left bundle-branch block. In 14 patients a clinical diagnosis of acute myocardial infarction was made, but it was found that none of the seven most promising ECG criteria suggested in the literature could alone or in combination diagnose acute myocardial infarction. QRS vector difference evolution showed the same kind of pattern as that for patients with narrow QRS-complex. By using a predefined specific pattern, a diagnostic accuracy of 79% was achieved. The results indicate that dynamic vectorcardiography is a better tool for diagnosing and monitoring acute myocardial infarction in patients with left bundle-branch block than standard 12-lead ECGs taken on admission and after 12-24 h.     

Early vectorcardiographic monitoring provides prognostic information in patients with ST-elevation myocardial infarction

OBJECTIVE: To evaluate the prognostic value of specified vectorcardiographic data obtained during the first hours of ST-elevation myocardial infarction for cardiac outcomes up to 5 years. DESIGN: Three hundred and five patients with ST-elevation myocardial infarction and chest pain for less than 12 h were monitored with continuous vectorcardiography. RESULTS: All patients had follow-up for at least 1 year. The mortality was 5.9% at 30 days and 10.8% at 1 year. The estimated 5-year mortality was 24%. A total of 7.9% had recurrent infarction at 30 days and 11.2% at 1 year. Recurrent infarction or death occurred in 12.1% at 30 days and in 19.7% at 1 year. The presence of ST-VM (plateau) >or= 125 microV was highly predictive of the combined endpoint death or recurrent infarction at 1 year, OR 2.69 (95% CI 1.39-5.23). Multivariate analysis showed that age >or=75 years, anterior myocardial infarction, and the presence of ST-VM (plateau) >or= 125 microV, were independently associated with increased risk of recurrent infarction or death at 1 year and with death at 5-year follow-up. A start value of ST-VM 相似文献   

Myocardial ischaemia during non-cardiac surgery. A comparison of different lead systems using computerised ST segment analysis

Computerised ST segment analysis was used to compare the frequency of ischaemia occurring in electrocardiographic leads II, V5, CS5 and CB5. Three out of 15 patients with ischaemic heart disease developed ischaemic changes, which were evident in all four leads in each patient. A single bipolar lead may be substituted for a true V5 lead when monitoring patients at increased risk of developing myocardial ischaemia. ST segment analysis facilitates the early diagnosis of peri-operative myocardial ischaemia, which may otherwise be missed on the standard electrocardiogram.     

Early vectorcardiographic monitoring provides prognostic information in patients with ST-elevation myocardial infarction

Objective--To evaluate the prognostic value of specified vectorcardiographic data obtained during the first hours of ST-elevation myocardial infarction for cardiac outcomes up to 5 years. Design--Three hundred and five patients with ST-elevation myocardial infarction and chest pain for less than 12?h were monitored with continuous vectorcardiography. Results--All patients had follow-up for at least 1 year. The mortality was 5.9% at 30 days and 10.8% at 1 year. The estimated 5-year mortality was 24%. A total of 7.9% had recurrent infarction at 30 days and 11.2% at 1 year. Recurrent infarction or death occurred in 12.1% at 30 days and in 19.7% at 1 year. The presence of ST-VM[Formula: See Text]?≥?125?μV was highly predictive of the combined endpoint death or recurrent infarction at 1 year, OR 2.69 (95% CI 1.39-5.23). Multivariate analysis showed that age ≥75 years, anterior myocardial infarction, and the presence of ST-VM[Formula: See Text]?≥?125?μV, were independently associated with increased risk of recurrent infarction or death at 1 year and with death at 5-year follow-up. A start value of ST-VM ≤?100?μV identified a group of patients with low risk of death or re-infarction within 1 year. Conclusion--Continuous vectorcardiography during the first hours after thrombolytic treatment of patients with ST-elevation myocardial infarction provides important prognostic information. A new vectorcardiographic variable, ST-VM[Formula: See Text], identifies a group of patients with increased risk of recurrent infarction or death. As well, patients with low risk of recurrent infarction or death were identified by low start values of ST-VM.     

Vectorelectrocardiography in coronary artery disease

Continuous ST-segment monitoring by either continuous 12-lead ECG or continuous vectorcardiography provides reliable information regarding ST changes in patients with ongoing myocardial ischemia with or without concurrent chest pain. ST-segment monitoring enables the clinician to continuously follow the dynamic changes that characterize unstable angina and acute myocardial infarction syndromes. It provides important information for risk stratification in unstable coronary syndromes and helps in differentiating between extra-cardiac chest pain and acute coronary disease. The use of VECG for detection of perioperative myocardial damage is promising but much work still needs to be done to clarify the prognostic and clinical value of VECG in this setting.     

Randomized clinical trial of the effect of pneumoperitoneum on cardiac function and haemodynamics during laparoscopic cholecystectomy

BACKGROUND: Conventional laparoscopic cholecystectomy (CLC) with carbon dioxide pneumoperitoneum may cause major cardiovascular changes. The aim of this study was to evaluate the effect of carbon dioxide pneumoperitoneum and positional changes on haemodynamics and cardiac function in patients assigned randomly to CLC or gasless laparoscopic cholecystectomy (GLC). METHODS: Fifty patients with American Society of Anesthesiologists physical status I and II were randomly allocated to CLC (28 patients) or GLC (22). Left ventricular end-diastolic and end-systolic diameters, fractional shortening and cardiac output were determined by transoesophageal echocardiography. Measurements were performed before (phase 1) and 10 and 30 min (phases 2 and 3 respectively) after pneumoperitoneum or abdominal wall traction, and after desufflation or release of abdominal wall traction (phase 4) in supine, Trendelenburg and reverse Trendelenburg positions. RESULTS: Mean diastolic diameter, systolic diameter, mean arterial pressure and heart rate were significantly higher, and fractional shortening was significantly lower, with carbon dioxide pneumoperitoneum than with the gasless procedure during phases 2 and 3. There were no significant differences in cardiac output between the two groups. CONCLUSION: Carbon dioxide pneumoperitoneum was associated with increased preload and afterload in patients undergoing laparoscopic cholecystecomy. It also decreased heart performance (fractional shortening), but did not affect cardiac output.     

Myocardial ischaemia in normal patients undergoing elective Caesarean section: a peripartum assessment

Incidence rates of electrocardiographic changes during Caesarean section vary from 25 to 60%. To date, no investigator has identified myocardial ischaemia resulting from these changes. We investigated patients undergoing elective Caesarean section using peripartum Holter monitoring and serum analysis of cardiac troponin I (cTnI). Twenty-six patients presenting for elective Caesarean section were studied. Peroperative Holter monitoring continued for 12 h postoperatively, at which time blood samples for cTnI levels were taken. Significant ST changes were recorded in 42% of patients peroperatively and 38.5% of patients postoperatively. Forty-two per cent of patients experienced peroperative chest pain requiring opioid analgesia. Chest pain was significantly associated with abnormal electrocardiogram (ECG) findings. Ischaemic levels of cTnI were recorded in two patients. This study reports, for the first time, myocardial ischaemia (7.69% of patients) arising in conjunction with the ECG changes seen during elective Caesarean section. We also report episodes of significant postoperative ST-segment changes.     

二氧化碳气腹对老年胆石症病人心血管系统影响的临床研究

目的:探讨腹腔镜手术CO2气腹对老年胆石症病人心血管系统的影响,以减少和预防并发症,提高腹腔镜手术的安全性.方法:选择60例老年胆石症腹腔镜手术病人.观察CO2气腹不同阶段心率、血压、血氧饱和度、心电图、心肌酶谱的变化,分析其临床意义及预防对策.结果:建立CO2气腹时心率减慢、血压明显降低,气腹后30分钟心率加快、血压升高,心电图变化主要表现为心律失常(36%)及T波改变(30%),于气腹消退后10min恢复.心肌酶谱、血氧饱和度无明显改变.结论:CO2气腹过程中可引起一过性心率、血压、心电图的变化,对心功能异常的病人术中应进行严密心电监护,腹腔镜手术对老年胆石症病人是安全有效的治疗手段.     

The effect of pneumoperitoneum in the steep Trendelenburg position on cerebral oxygenation

Background: daVinci^® robot‐assisted laparoscopic radical prostatectomy (RALP) requires pneumoperitoneum in the steep Trendelenburg position, which results in increased intracranial pressure and cerebral blood flow. The aim of this study was to evaluate the effect of pneumoperitoneum in a 30° Trendelenburg position on cerebral oxygenation using regional cerebral oxygen saturation (rSO₂). Methods: Thirty‐two male patients of ASA I and II physical status without previous episodes of cerebral ischemia or hemorrhage undergoing daVinci^® RALP were enrolled. The rSO₂ was continuously monitored with near‐infrared spectroscopy (INVOS^® 5100^?) during the study period. Measurements were obtained immediately after anesthesia induction (T0; baseline), 5 min after a 30° Trendelenburg position (T1), 5 min after 15 mmHg pneumoperitoneum in a supine position (T2), 30, 60 and 120 min after the pneumoperitoneum in a Trendelenburg position (T3, T4 and T5, respectively) and after desufflation in a supine position (T6). Results: The change in the left and right rSO₂ was statistically significant (Left P=0.004 and Right P=0.023). Both the right and the left rSO₂ increased significantly during pneumoperitoneum in a Trendelenburg position (from T3 to T5) and at T6 compared with the baseline value at T0. The partial pressure of carbon dioxide (PaCO₂) was increased significantly at T2, T3, T5 and T6 compared with the baseline value at T0. Conclusions: During daVinci^® RALP, cerebral oxygenation, as assessed by rSO₂, increased slightly, which suggests that the procedure did not induce cerebral ischemia. The PaCO₂ should be maintained within the normal limit during pneumoperitoneum in a Trendelenburg position in patients undergoing daVinci^® RALP because the rSO₂ increased in conjunctions with the increase in PaCO₂.