Continuous Electrocardiography Research Articles

Design of Seat Mounted ECG Sensor System for Vehicle Application

The causes of deaths in traffic accidents are predominantly human factors such as careless or heedlessness driving; recently, accidents that are believed to be due to deteriorated physical conditions, such as heart attacks, have been reported. Non-contact electrocardiography(ECG) monitor for continuous ECG detection while driving is needed to reduce a number of fatal accident by human error like this. Recently there are a lot of papers to detect cardiac electricity using capacitance coupling between human body and electrode. This sensor system must be adopted appropriate high input impedance circuit and noise reduction technique as a function of source impedance value especially for a seat mounted sensor. We investigated the impedances of the intermediary materials such as a seat cover and clothing for installing vehicle use by dielectrics measurement system can measure extra-high impedance (100TΩ), and designed an effective circuit configuration for common noise resistance, considering the effect of the sitting posture according to their results. The sensor system employed the DRL (Driven Right Leg) circuit is composed of two sensor head mounted into the seat cover and a electrode mounted on a steering wheel for reducing well common mode noise in cardiac electricity frequency. We have succeeded in attaining stable detection of cardiac electrical impulses during two driving conditions, stable driving at the average speed of 70km/h and driving with frequent changes at the speed of 0-30km/h, operations of the accelerator, brake, steering wheel, and direction indicator. Language: en

Accuracy of Determining Hemoglobin Level Using Occlusion Spectroscopy in Patients with Severe Gastrointestinal Bleeding

In patients presenting with severe hemorrhage, the authors conducted an equivalence trial that compared noninvasive occlusion spectroscopy and the capillary blood method to determine hemoglobin level. This prospective observational study included patients admitted to their intensive care unit for gastrointestinal bleeding. A ring-shaped sensor, connected to a NBM-200MP (OrSense, Nes Ziona, Israel), was fitted onto the patient's thumb to intermittently measure hemoglobin (SotHb). During the first 24 h after admission, venous hemoglobin level, considered as the reference method, was determined at the laboratory every 8 h and was compared to SotHb and the capillary blood method. The primary endpoint was the proportion of inaccurate measurements, defined as greater than 15% difference compared with reference values or their unavailability for any technical reason. The study was scheduled to include 68 patients but was stopped prematurely after an interim analysis of 34 patients. The proportion of inaccuracies revealed that SotHb could not be considered equivalent to the capillary blood method (47% [95% CI, 43-51] and 24% [95% CI, 20-28]). Considering venous hemoglobin level as a reference method, the mean biases for SotHb (n = 133) and the capillary blood method (n = 135) were, respectively, -0.4 ± 2.0 and 0.8 ± 1.2 g/dl (P < 0.05). SotHb was associated with an increased incidence of failed transfusion. The inaccuracy of SotHb tended to be increased in patients receiving vasopressor agents. Noninvasive determination of hemoglobin level based on occlusion spectroscopy lacks accuracy in patients presenting with severe gastrointestinal bleeding and cannot be considered equivalent to the capillary-based method. This inaccuracy seems to be moderately influenced by the infusion of vasopressor agents.

Risk factors and outcomes of persistent pulmonary hypertension of the newborn in neonatal intensive care unit of al-minya university hospital in Egypt

Background:Persistent pulmonary hypertension of the newborn (PPHN) result from the failure of the normal fetal-to-neonatal circulatory transition is associated with substantial infant mortality and morbidity.Objective:To estimate the possible risk factors and assess the outcome of these cases.Materials and Methods:Prospective study was performed enrolling all full-term and post-term newborn admitted to the NICU from January 2009 to April 2012, All neonates were subjected to complete history and physical examination, laboratory data including a complete blood count, arterial blood gases, blood glucose, serum electrolytes, and blood culture to exclude sepsis. Cases with PPHN had a continuous pulse oximeter, blood pressure and electrocardiography monitoring. Chest X-ray and echocardiogarphy were carried out to verify shunt and exclude structural congenital heart disease.Results:Out of the studied 640 infants, 32 infants (5%) developed PPHN, Meconium aspiration, birth asphyxia, hyaline membrane diseases, neonatal septicemia, post-term birth being large for gestational age, cesarean section, maternal overweight, and diabetes mellitus were associated with an elevated risk for PPHN. All neonates treated with O2, 10 neonates with Mg sulphate, 16 with oral sildenafil and 12 with mechanical ventilation. After 6 months follow-up, 12 (37.54%) improved and followed-up without sequelae, 4 (12.5%) developed some neurodevelopmental impairment, 8 (25%) died, 3 (9.3%) developed chronic lungs diseases, 2 (6.2%) developed hearing defects and another 3 (9.3%) missed follow-up.Conclusion:PPHN was found in 5% of the studied population. Meconium aspiration, birth asphyxia, neonatal septicemia, post-term were associated with an elevated risk for PPHN. As this is a unit based study, a comprehensive countrywide survey on PPHN in Egypt is recommended to determine any regional differences in disease incidence.

A Recipe for Perioperative Cardioprotection

The question of what is the ideal anesthetic for patients with cardiovascular disease has been debated for nearly 3 decades, and, similar to the case for the use of perioperative β-blockers, the answer appears to be increasingly enigmatic. In the current issue of Circulation , Buse et al1 report the results of a randomized clinical trial to evaluate the effects of the volatile anesthetic sevoflurane versus the intravenous anesthetic propofol on the incidence of myocardial ischemia in 385 patients with known coronary artery disease or with ≥2 risk factors for coronary artery disease undergoing noncardiac surgery. Using continuous electrocardiography and troponin T plasma concentrations as the composite primary end point of the study, the incidence of myocardial ischemia was similar in both groups (sevoflurane, 40.8%; propofol, 40.3%), calling into question the current American College of Cardiology/American Heart Association guidelines recommending the use of volatile anesthetics for patients at cardiovascular risk who are undergoing noncardiac surgery.2 Article see p 2696 In the mid-1980s, volatile anesthetic agents, particularly isoflurane, were shunned by cardiac anesthesiologists for fear that these agents might induce myocardial ischemia because of coronary steal. High-dose opioids were favored as an alternative technique during anesthesia for cardiac surgery. The myth of isoflurane-induced steal was later debunked both by animal studies3 and clinical trial data.4 By the early 1990s, volatile anesthetic use during cardiac surgery had gained considerable popularity, primarily because it allowed patients to be fast-tracked for early extubation within hours of arrival to the intensive care unit as compared with opioid-based anesthetics. In 1997, the phenomenon of anesthetic preconditioning was first described,5 and subsequently a large body of experimental evidence …

CONTINUOUS COMPRESSION WITHOUT DEFIBRILLATION FAVOURED NO SHORT-TERM SURVIVAL IN PROLONGED VENTRICULAR FIBRILLATION

CONTINUOUS COMPRESSION WITHOUT DEFIBRILLATION FAVOURED NO SHORT-TERM SURVIVAL IN PROLONGED VENTRICULAR FIBRILLATION

Left Atrial Strain Assessed by Speckle Tracking Imaging Is Related to New-Onset Atrial Fibrillation After Coronary Artery Bypass Grafting

Left atrial (LA) dysfunction was recently proposed as an important factor in the development of postoperative atrial fibrillation (POAF). LA strain analysis by 2-dimensional (2D) speckle tracking imaging is emerging as a new tool to evaluate LA function. We aimed to evaluate the correlation of LA dysfunction assessed by 2D speckle tracking imaging with the occurrence of POAF after coronary artery bypass grafting (CABG). In this study, 53 patients (mean age 66 ± 9 years) undergoing elective isolated CABG were enrolled. Conventional transthoracic echocardiography and 2D speckle tracking strain analysis were performed before surgery. POAF was detected with continuous electrocardiography monitoring throughout hospitalization (mean duration 17 ± 10 days). POAF occurred in 13 of 53 patients (24%). Patients with POAF were significantly older than patients with normal sinus rhythm after surgery (71 ± 5 vs 64 ± 10 years, P = 0.026). Compared with patients with normal sinus rhythm, patients with POAF had a significantly larger LA volume index (32.6 ± 5.1 vs 27.3 ± 7.2 mL/m(2), P = 0.018), lower value of LA global strain (25.4 ± 10.4 vs 36.8 ± 7.6%, P = 0.001), and strain rate (1.2 ± 0.6 vs 1.6 ± 0.8 seconds, P = 0.024). By multivariate logistic regression analysis, only LA global strain (odds ratio, 1.12; 95% confidence interval, 1.00-1.24; P = 0.040) was an independent predictor of POAF after CABG. Preoperative LA global strain measured by 2D speckle tracking strain analysis is associated with the development of POAF after CABG.

Continuous Stroke Unit Electrocardiographic Monitoring Versus 24-Hour Holter Electrocardiography for Detection of Paroxysmal Atrial Fibrillation After Stroke

Cardioembolism in paroxysmal atrial fibrillation (pxAF) is a frequent cause of ischemic stroke. Sensitive detection of pxAF after stroke is crucial for adequate secondary stroke prevention; the optimal diagnostic modality to detect pxAF on stroke units is unknown. We compared 24-hour Holter electrocardiography (ECG) with continuous stroke unit ECG monitoring (CEM) for pxAF detection. Patients with acute ischemic stroke or transient ischemic attack were prospectively enrolled. After a 12-channel ECG on admission, all patients received 24-hour Holter ECG and CEM. Additionally, ECG monitoring data underwent automated analysis using dedicated software to identify pxAF. Patients with a history of atrial fibrillation or with atrial fibrillation on the admission ECG were excluded. Four hundred ninety-six patients (median age, 69 years; 61.5% male) fulfilled all inclusion criteria (ischemic stroke: 80.4%; transient ischemic attack: 19.6%). Median stroke unit stay lasted 88.8 hours (interquartile range, 65.0-122.0). ECG data for automated CEM analysis were available for a median time of 64.0 hours (43.0-89.8). Paroxysmal AF was documented in 41 of 496 patients (8.3%). Of these, Holter detected pxAF in 34.1%; CEM in 65.9%; and automated CEM in 92.7%. CEM and automated CEM detected significantly more patients with pxAF than Holter (P<0.001), and automated CEM detected more patients than CEM (P<0.001). Automated analysis of CEM improves pxAF detection in patients with stroke on stroke units compared with 24-hour Holter ECG. The comparative usefulness of prolonged or repetitive Holter ECG recordings requires further evaluation.

“Perseverant Heart”

“Perseverant Heart”

Taking ECGs: being skilled, competent and confident

The phrase ‘cardiac monitoring’ usually refers to either continuous or one-off electrocardiograph (ECG). There are many ways of monitoring cardiac function, for example, telemetry (this allows cardiac monitoring to be done at a distance) and haemodynamic monitoring (monitors the pressure and flow of blood within the circulatory system). This article provides the healthcare assistant (HCA) and assistant practitioner (AP) with a brief introduction to the ECG. An overview of the anatomy and electrophysiology of the heart is provided. Emphasis is placed on ensuring that the person is safe and comfortable before, during and after the procedure. The equipment needed to obtain an accurate 3-lead ECG is discussed, as well as providing a description of the appropriate positioning of the leads on the person's body.

Relation Between Zinc, Copper, and Magnesium Concentrations Following Cardiopulmonary Bypass and Postoperative Atrial Fibrillation in Patients Undergoing Coronary Artery Bypass Grafting

Atrial fibrillation is the most frequently encountered arrhythmia following cardiac surgery. Since the essential trace elements zinc, copper, and magnesium are suspected to have an effect on postoperative atrial fibrillation, the concentrations of these elements were determined by flame atomic absorption spectrophotometry in the plasma of 60 patients undergoing elective coronary artery bypass grafting. Blood samples were collected every 30 min during cardiopulmonary bypass and postoperatively. Plasma concentrations of copper, zinc, and magnesium were measured with flame atomic absorption spectrophotometry. All patients were monitored by continuous electrocardiography until they became outpatients or immediately after atrial fibrillation had taken place. Atrial fibrillation occurred in 13 of the 60 patients, corresponding to 21.7%. The zinc and copper concentrations at postoperative days 1 and 3 were significantly different (P < 0.05) between patients with and without atrial fibrillation. The concentrations of zinc following cardiopulmonary bypass recovered more slowly in patients with postoperative atrial fibrillation than in patients without it. Whether or not supplemental zinc could lower the incidence of postoperative atrial fibrillation should be evaluated in future prospective randomized clinical trials.

Association of rs10918594 Polymorphisms of Nitric Oxide Synthase 1 Adaptor Protein (NOS1AP) with QTc Interval Prolongation During Kidney Transplantation

Background The mechanisms of sudden cardiac death are difficult to recognize, but repolarization disturbances have been shown to be the cause. The purpose of this study was to investigate whether the polymorphism of nitric oxide synthase 1 adaptor protein (NOS1AP) was related to the risk of occurrence of corrected QTc-interval prolongation and ventricular arrhythmias recorded on electrocardiography (ECG) Holter monitoring in kidney transplant recipients. Study Design The 75 adult first kidney transplant patients included 43 men with an overall mean age of 45 ± 12 years (range, 20–68). Additional patient monitoring during the procedure and in the postoperative period consisted of a continuous ECG tracing recording and investigation of the rs10918594 NOS1AP polymorphism. Results We observed Transient QTc-interval prolongation during the perioperative period. NOS1AP genotypes were in Hardy-Weinberg equilibrium. For further statistical analysis, we combined GG homozygotes and CG heterozygotes because of the small numbers available; therefore, only a dominant mode of inheritance was investigated. There were no gender differences in QTc-interval patterns. Analysis of variance with repeated measures revealed no interaction between NOS1AP and QTc-interval values taken at various times among the kidney recipients. Conclusions The transplantation procedure may lead to dynamic repolarization disturbances, which may produce an increased risk of severe arrhythmias despite optimization of patient status. The NOS1AP rs203462 polymorphisms did not correlate with an increased risk of QT interval prolongation among kidney recipients.

Preoperative left atrial dysfunction and risk of postoperative atrial fibrillation complicating thoracic surgery

Postoperative atrial fibrillation complicating general thoracic surgery increases morbidity and stroke risk. We aimed to determine whether preoperative atrial dysfunction or other echocardiographic markers are associated with postoperative atrial fibrillation. In 191 patients who had undergone anatomic lung or esophageal resection, preoperative clinical and echocardiographic data were compared between patients with and without postoperative atrial fibrillation. Presence of postoperative atrial fibrillation lasting more than 5 minutes during hospitalization was detected using continuous telemetry or 12-lead electrocardiography. Maximal left atrial volume and indices of left atrial function were assessed. Patients with postoperative atrial fibrillation (33/191, 17%) were older (71 ± 5 years vs 64 ± 12 years, P < .0001), were taking β-blockers more often, had greater left atrial volume, had decreased left atrial emptying fraction, and had lower E' and A' septal velocities compared with patients without postoperative atrial fibrillation. The incidence of postoperative atrial fibrillation in patients with left atrial volume 32 mL/m(2) or greater was 37% (11/30) and greater than in those with left atrial volume less than 32 mL/m(2) (14%, 22/160, P = .002). Length of hospital stay was significantly increased in patients with postoperative atrial fibrillation compared with patients without (P = .04). Older age was significantly associated with greater β-blocker use and left atrial volume and lower left atrial emptying fraction. On multivariate analysis, lower left atrial emptying fraction (odds ratio, 1.03 per unit decrement; 95% confidence interval, 1.002-1.065; P = .04) and preoperative use of β-blockers (odds ratio, 2.82; 95% confidence interval, 1.18-6.77; P = .02) were the only independent risk factors associated with postoperative atrial fibrillation. These data show that an echocardiogram before major thoracic surgery, increased use of preoperative β-blockers, and decreased left atrial emptying fraction were associated with postoperative atrial fibrillation. Echocardiographic predictors of left atrial mechanical dysfunction may prove clinically useful in risk stratifying patients in whom postoperative atrial fibrillation is more likely to develop and to benefit from prevention strategies aimed at mitigating atrial function before surgery.

Hemodynamic instability following carotid artery stenting

Postprocedural hypotension and bradycardia are important complications of carotid artery stenting (CAS) and are referred to as hemodynamic instability (HI). However, the incidence and impact of HI on the short-term prognosis of patients have been of a large debate. Twenty-seven patients were selected based on NASCET criteria, and they underwent CAS between September 2008 and September 2009. Continuous electrocardiography monitoring and supine blood pressure (BP) monitoring were performed before and after stent deployment and on the following day to detect HI, defined as systolic BP lower than 90 mm Hg or a heart rate lower than 60 bpm. Patients were asked to perform a Valsalva maneuver before and after stent deployment. The Valsalva ratios (VRs) along with other demographic and procedural data were documented and compared between patients with and without incidence of HI. Seventeen patients (63%) developed HI after CAS. The degree of stenosis was found to have a significant correlation with occurrence of HI (p < 0.006). No other risk factor or demographic data showed any correlation with HI. The VRs were significantly lower in the HI group compared with the non-HI group, indicating a significant autonomic dysfunction (p < 0.003). During follow-up, 1 patient (4.3%) developed major stroke, and the remaining patients were symptom free. Hemodynamic instability occurs frequently after CAS, but it seems to be a benign phenomenon and does not increase the risk of mortality or morbidity in the short term. A VR at rest less than 1.10, baseline autonomic dysfunction, and degree of carotid artery stenosis can be used as measures for predicting HI after CAS.

Depressed sympathovagal balance predicts mortality in patients with subarachnoid hemorrhage

ObjectivesThe objective of this study is to investigate the role of sympathovagal balance in predicting inhospital mortality by assessing power spectral analysis of heart rate variability (HRV) among patients with nontraumatic subarachnoid hemorrhage (SAH) in an emergency department (ED). MethodsA cohort of 132 adult patients with spontaneous SAH in an ED was prospectively enrolled. A continuous 10-minute electrocardiography for off-line power spectral analysis of the HRV was recorded. Using the inhospital mortality, the patients were classified into 2 groups: nonsurvivors (n = 38) and survivors (n = 94). The HRV measures were compared between these 2 groups of patients. ResultsHaving compared the various measurements, the very low–frequency component, low-frequency component, normalized low-frequency component (LF%), and low-/high-frequency component ratio (LF/HF) were significantly lower, whereas the normalized high-frequency component was significantly higher among the nonsurvivors than among the survivors. A multiple logistic regression model identified LF/HF (odds ratio, 2.16; 95% confidence interval [CI], 1.18-3.97; P = .013) and LF% (odds ratio, 0.78; 95% CI, 0.69-0.88; P < .001) as independent variables that were able to predict inhospital mortality for patients with SAH in an ED. The receiver operating characteristic area for LF/HF in predicting inhospital mortality was 0.957 (95% CI, 0.914-1.000; P < .001), and the best cutoff points was 0.8 (sensitivity, 92.1%; specificity, 90.4%). ConclusionsPower spectral analysis of the HRV is able to predict inhospital mortality for patients after SAH in an ED. A tilt in the sympathovagal balance toward depressed sympathovagal balance, as indicated by HRV analysis, might contribute to the poor outcome among these patients.

Index of Suspicion in the Nursery

A woman is admitted for induction of labor at 40-3/7 weeks' gestation. Prenatal care was initiated at 21 weeks' gestation. Ultrasonographic examinations at 23 and 34 weeks' gestation revealed a slightly enlarged right kidney and polyhydramnios, with amniotic fluid indices of 18.6 and 26.7, respectively. An emergency cesarean section is performed for fetal distress. Meconium-stained fluid is noted at delivery. A female infant weighing 3,140 g (10th to 25th percentile for weight) is delivered and assigned Apgar scores of 2, 5, and 9 at 1, 5, and 10 minutes, respectively. At delivery, she is flaccid and apneic but responds quickly to nasal and oral suctioning, stimulation, and bag-mask ventilation. She requires endotracheal intubation for worsening respiratory distress and desaturations. Her initial chest radiograph shows an enlarged cardiac silhouette and diffusely hazy lung fields (Fig. 1). An additional study is performed, which helps to explain the infant's presentation. Figure 1. Chest radiograph shows an enlarged cardiac silhouette and bilateral streaky opacities. Physical examination reveals a grade II/VI systolic ejection murmur along the left sternal border without radiation. Peripheral pulses are diminished in all extremities. She is having moderate respiratory distress on mechanical ventilation support. Her abdomen is soft but distended, and the liver edge is palpable 4 cm below the right costal margin and extends across the midline. No splenomegaly is noted. A palpable mass in the right flank is also detected. A three-vessel cord is present, with a prominent umbilical vein. An abdominal radiograph demonstrates a paucity of bowel gas consistent with ascites and hepatomegaly (Fig. 2). Laboratory results include a white blood cell count of 8.0×103/μL (8.0×109/L) with a normal differential count, a hematocrit of 24% (0.24), and a platelet count of 71×103/μL (71×109/L). Bacterial and viral cultures are negative. Figure 2. Abdominal radiograph of …

Cardiac Conduction Safety during Coadministration of Artemether-Lumefantrine and Lopinavir/Ritonavir in HIV-Infected Ugandan Adults

Background. We aimed to assess cardiac conduction safety of coadministration of the CYP3A4 inhibitor lopinavir/ritonavir (LPV/r) and the CYP3A4 substrate artemether-lumefantrine (AL) in HIV-positive Ugandans. Methods. Open-label safety study of HIV-positive adults administered single-dose AL (80/400 mg) alone or with LPV/r (400/100 mg). Cardiac function was monitored using continuous electrocardiograph (ECG). Results. Thirty-two patients were enrolled; 16 taking LPV/r -based ART and 16 ART naïve. All took single dose AL. No serious adverse events were observed. ECG parameters in milliseconds remained within normal limits. QTc measurements did not change significantly over 72 hours although were higher in LPV/r arm at 24 (424 versus 406; P = .02) and 72 hours (424 versus 408; P = .004) after AL intake. Conclusion. Coadministration of single dose of AL with LPV/r was safe; however, safety of six-dose AL regimen with LPV/r should be investigated.

Electroconvulsive Therapy Anesthesia Practice Patterns

To review anesthesia practice patterns associated with electroconvulsive therapy (ECT) in the UK. A 12-item questionnaire survey on the practice of ECT anesthesia was sent to all units in the UK identified as providing ECT services. One hundred thirty active ECT units were identified. Sixty-six (51%) responded. Forty-five percent of respondents worked in units located within acute hospital boundaries and 53% outside acute hospital boundaries. Forty-seven percent of respondents were associated with units providing consultant anesthetic cover for 75-100% of ECT sessions. Twenty-seven percent of the units did not use capnography, 17% did not use continuous electrocardiography, and 16% did not use noninvasive blood pressure monitoring. Results were entirely from respondents. No practices were directly observed. Although there is apparent widespread recognition of ECT Accreditation Service guidelines, compliance with recommended standards is variable. Given the typically high comorbidity of ECT patients, and indications of elevated anesthetic risk from non-UK studies, this has important implications for the safety of ECT anesthesia in the UK.

Management of ECG Cables and Leadwires

Electrocardiography (ECG) is the non-invasive capture and display (either on a screen or as a hard copy, such as a strip recording or page printout) of cardiac electrical activity. ECG provides a quick and highly reliable estimate of a patient’s cardiovascular health, making it one of the most common non-invasive medical applications. ECG is used for monitoring cardiac activity, for the purpose of diagnosis and therapy in clinics, and all areas of the hospital, including operating rooms and intensive care units (ICU). Physicians can use ECG to quickly measure heart rate and cardiac rhythm of a patient. The physician can also identify abnormalities in how electrical impulses propagate through the heart and detect evidence of coronary artery disease, prior heart attacks, and thickening of the cardiac muscle.1–4 For more detailed information about a patient’s cardiac electrical activity, a physician may request longer-term ECG recordings through the use of a Holter monitor (an ambulatory ECG) or during intentionally “loading” of the heart with a stress test, such as having the patient exercise on a treadmill. Continuous ECG monitoring during anesthesia provides vital information regarding a patient’s condition throughout a surgical procedure. Continuous ECG data acquisition using a bedside monitor provides real-time health information for a patient in an ICU. In some instances, pacemakers or defibrillators (external and internal) significantly alter the appearance of the body-surface ECG. Many medical activities, including life supporting or life saving ones, depend on efficient acquisition of ECG data. ECG has been used since Willem Einthoven invented the first practical ECG in 1903, receiving the Nobel Prize in Medicine in 1924 for his invention.5 ECG systems have evolved over many years. Now, ECG systems are built with similar building blocks, and all have similar external components. Electrical or mechanical failures occur infrequently for ECG devices themselves; however, malfunctions due to problems with ECG electrodes, leadwires, and ECG (patient) cables are common.6 This article reviews these problems and presents the results from a 2010 AAMI survey of biomedical equipment technicians (BMET)s and clinical engineers (CE)s. The article covers issues related to clinical management of the cables and leadwires, as well as potential improvements in the design of new medical devices to increase efficiency and reliability. ECG cables, leadwires, and electrodes are used to connect the human body to many different types of ECG devices. Hospitals usually have many medical devices that record and display ECG signals including Holter monitors, stress-testing equipment such as treadmills, patient monitors, telemetry units, defibrillators, and diagnostic electrocardiographs (often referred to as ECG or EKG carts). Large multi-specialty clinics may have treadmills and Holters, but these are generally run through a cardiology subspecialty group. (Smaller clinics and physicians’ offices also use some of these devices, but patient monitors and telemetry units are typically not on site.) These facilities stock large numbers of ECG cables, leadwires, and electrodes needed to use these devices. Poor electrodes and worn-out leadwires or ECG cables routinely cause failures that clinical users may not be able to readily identify. ECG cables and leadwires should be tested by a BMET regularly—or whenever an ECG device seems to be malfunctioning—and replaced when necessary. Leadwires should only be used if they remain in good condition (i.e., intact insulation, unbroken, no visible signs of wear). If a BMET is not available, cliniAhmet Turkmen, PhD, MS, BS, is an assistant professor with the Engineering and Technology Department at the University of Wisconsin–Stout. He is a co-chair of the AAMI ECG Committee. E-mail: turkmena@ uwstout.edu

Heart Rate Variability Response to Standing in Men and Women Receiving d,l-Sotalol Following Coronary Artery Bypass Graft Surgery

Heart rate variability (HRV), a quantitative marker of autonomic control of heart rate (HR), declines in men and women following coronary artery bypass graft (CABG) surgery. Although d,l-sotalol is prescribed following CABG surgery primarily for its antiarrhythmic effect, its effects on HRV have not been reported; the β-adrenergic antagonist effect of d,l-sotalol may attenuate sympathetically mediated HR and blood pressure (BP) responses to standing, resulting in postural hypotension. In this study, the HRV response to standing 4 days following CABG surgery in men and women prescribed d,l-sotalol was measured to examine the influence of d,l-sotalol on previously reported HRV responses, taking age and gender into consideration. Participants included 28 men and 10 women who completed testing in supine and standing postures; all had received low-dose d,l-sotalol daily since the first postoperative day. Data included continuous electrocardiograph recording of R-R interval for 10 min in each posture. Participants showed significant effects of standing on the autonomic modulation of HR, as seen by a decrease in parasympathetic indices and R-R interval and an increase in BP. In men, standing decreased parasympathetic modulation and increased the sympathetic nervous system indicator, but previously reported age effects were not seen. In women, standing decreased low frequency power and R-R interval and increased BP, with older women having a smaller increase in BP, suggesting an attenuated response. The differential autonomic nervous system modulation of HR as a function of gender and age after CABG surgery may be attenuated by d,l-sotalol.

Aortic Surgery Complications Evaluated by an Implanted Continuous Electrocardiography Device: A Case Report

Introduction Cardiac arrhythmias are a major cause for morbidity and mortality in patients undergoing non-cardiac vascular surgery. Report An implantable loop recorder (Reveal ® XT) was used for continuous heart rhythm monitoring to detect perioperative arrhythmias in a 69-year-old man undergoing major vascular surgery for an infected aortobifemoral prosthesis. The Reveal ® detected several episodes of asymptomatic new-onset atrial fibrillation postoperatively, associated with elevated serum levels of troponin-T and N-terminal pro-B-type natriuretic peptide NT-proBNP). Discussion Continuous heart rhythm monitoring with assessment of serum cardiac biomarkers may allow early identification and treatment of patients at high risk of perioperative cardiovascular complications, in particular, cardiac arrhythmias.