This beneficial effect may be in part due to a modest effect of metformin on reducing blood pressure unrelated to weight loss , improving lipid profiles especially triglycerides and endothelial function, reducing fibrinogen levels, and possibly increasing fibrinolysis. Metformin's most common side effect is gastrointestinal distress, which includes nausea, diarrhea and upper abdominal discomfort. Nair explains: "These symptoms are more likely to occur when patients ingest metformin on an empty stomach and may be mitigated by taking metformin in the middle of the meal or using a sustained-release formulation.
The exact reasons for the gastrointestinal adverse effects are not fully understood, but there is evidence that local serotonin production may be stimulated by metformin in the gut. Slow-release metformin does not cause a rapid increase in the blood metformin levels, and a similar effect may occur when taking metformin during a meal.
Metformin use started in France in , but it was not introduced in the United States until , nearly 20 years after the biguanide phenformin was taken off the market because of its risk of lactic acidosis, which was often fatal. Metformin has about 24 times less reported incidents of lactic acidosis compared with phenformin. James highlights: "There are many reasons why metformin causes less lactic acidosis than phenformin. It is a less powerful inhibitor of mitochondrial respiration, which is probably the main reason for its decreased risk of lactic acidosis compared with phenformin's and buformin's.
Moreover, metformin increases lactate oxidation and does not increase the release of lactate from muscle, unlike phenformin. In conditions such as circulatory failure, sepsis, and anoxia or hypoxia, metformin use may result in lactic acidosis and should be avoided. Metformin interacts with some medications, including cimetidine because its metabolism is partially inhibited by metformin, thereby increasing cimetidine concentration. Although metformin has been used for almost five decades, its mechanism of action is not fully understood.
Nair highlights: "Human studies indicate the mechanistic hypoglycemic action of metformin is its inhibition of hepatic glucose production, but the underlying mechanism for this inhibition of gluconeogenesis is not fully understood. Preclinical studies in rodents demonstrated that metformin acts by inhibiting endogenous glucose production by limiting the use of glucose precursors for gluconeogenesis.
Another preclinical study reported that metformin acts by inhibiting glucagon-induced hepatic glucose production. Standard cardiac event monitors come with 5 to 10 mins of memory. Cardiac event monitors with expanded memory capabilities have been developed, extending memory from approximately 20 to 30 mins Instromedix, ; LifeWatch, ; Philips Medical Systems, ; PDSHeart, to as much as several hours CardioPhonics, ; CardioPhonics, Extended memory is especially useful for automatic trigger cardiac event monitors, because the automatic trigger may not reliably discriminate between clinically significant arrhythmias true positives and EKG artifacts false positives , such that a more limited memory would be filled with false positives.
Mobile cardiovascular telemetry MCT refers to non-invasive ambulatory cardiac event monitors with extended memory capable of continuous measurement of heart rate and rhythm over several days, with transmission of results to a remote monitoring center. Mobile cardiovascular telemetry is similar to standard cardiac telemetry used in the hospital setting. These ECG results are transmitted over standard telephone lines to the remote monitoring center at the end of each day.
The physician receives both urgent and daily reports. The manufacturer states that an important advantage of MCOT is that it is capable of detecting asymptomatic events and transmitting them immediately, even when the patient is away from home, allowing timely intervention should a life-threatening arrhythmia may occur. Potential uses of MCOT include diagnosis of previously unrecognized arrhythmias, ascertainment of cause of symptoms, and initiation of anti-arrhythmic drug therapy.
The CardioNet device is not intended for monitoring patients with life-threatening arrhythmias FDA, There is reliable evidence that MCT is superior to patient-activated external loop recorders for diagnosing cardiac arrhythmias. Subjects with symptoms of syncope, pre-syncope, or severe palpitations who had a non-diagnostic hour Holter monitor were randomized to MCT or an external loop recorder for up to 30 days. The primary endpoint was the confirmation or exclusion of a probable arrhythmic cause of their symptoms.
A total of patients who completed the monitoring period were analyzed. The authors noted that cardiac arrhythmias without associated symptoms, but nonetheless capable of causing the index symptoms, were the major determining factor accounting for the difference in diagnostic yield of MCT and patient-activated external loop recorders. There is also evidence to suggest that MCT is superior to auto-triggered external loop recorders for diagnosing symptoms thought to be due to a cardiac arrhythmia.
Cardiac Event Monitors
Loop recorders with auto-trigger algorithms have been used to improve the diagnostic yield of event monitors Strickberger et al, Rothman et al explained that their study of MCT was not designed to evaluate auto-triggered loop recorders, as this type of recorder was not available at all study sites.
One possible factor accounting for the poor diagnostic yield of the auto-trigger loop recorders employed in this study is that they may have had limited memory which quickly filled with artifact.
The investigators sought to overcome this bias by having all monitoring strips and diagnoses evaluated by another electrophysiologist that was blinded to assignment. Another limitation of this study is that it did not explore the potential for work-up bias; the study did not describe whether any of the study subjects had ever had previous work-ups for cardiac arrhythmias that included evaluation with an external loop recorder. A number of retrospective uncontrolled studies have been published that have described the experience with MCT. This study is of similar design to an earlier study by Joshi et al , which reported on the first consecutive patients monitored by MCT.
The authors concluded that MCT has potential utility for this use. The Heartlink II Monitor is able to wirelessly transmit abnormal EKG waveforms from a base station in the home to a remote monitoring center. The VST is a wireless belt-like device with non-adhesive electrodes that is worn around the patient's chest.
The VST has an integrated microprocessor and wireless modem to automatically detect and transmit abnormal ECG waveforms. The monitoring center also provides daily reports that can be accessed by the patient's physician over the Internet. According to the manufacturer, a new VST device is being developed that will also provide data on the patient's oxygen saturation, blood pressure, and weight Biowatch Medical, Lifewatch Inc.
The LifeStar ACT cardiac monitoring system utilizes an auto-trigger algorithm to detect atrial fibrillation, tachycardia, bradycardia, and pauses, and requires no patient intervention to capture or transmit an arrhythmia when it occurs. The device can also be manually triggered by the patient during symptoms. The LifeStar ACT has a longer continuous memory loop that can be retrieved as needed by the monitoring center. Therefore, the evidence is sufficient to conclude that real-time continuous attended monitoring leads to change in disease management in significantly more patients than do certain ELRs [external loop recorders].
However, because this is a single multicenter study, the strength of evidence supporting this conclusion is weak. The Zio Patch uses a patch that is placed on the left pectoral region. The patch does not require patient activation. At the end of the recording period, the patient mails back the recorder in a prepaid envolope to a central monitoring station Mittal et al, A report is provided to the ordering physician within a few days.
Mittal et al noted that "clinical experience [with the Zio Patch] is currently lacking". Rosenberg et al compared the Zio Patch, a single-use, non-invasive waterproof long-term continuous monitoring patch, with a hour Holter monitor in 74 consecutive patients with paroxysmal atrial fibrillation AF referred for Holter monitoring for detection of arrhythmias. The Zio Patch was well-tolerated, with a mean monitoring period of Over a hour period, there was excellent agreement between the Zio Patch and Holter for identifying AF events and estimating AF burden.
Although there was no difference in AF burden estimated by the Zio Patch and the Holter monitor, AF events were identified in 18 additional individuals, and the documented pattern of AF persistent or paroxysmal changed in 21 patients after Zio Patch monitoring. Other clinically relevant cardiac events recorded on the Zio Patch after the first 24 hours of monitoring, including symptomatic ventricular pauses, prompted referrals for pacemaker placement or changes in medications.
As a result of the findings from the Zio Patch, The authors concluded that the Zio Patch was well-tolerated, and allowed significantly longer continuous monitoring than a Holter, resulting in an improvement in clinical accuracy, the detection of potentially malignant arrhythmias, and a meaningful change in clinical management.
Moreover, they stated that further studies are necessary to examine the long-term impact of the use of the Zio Patch in AF management. Turakhia and colleagues noted that although extending the duration of ambulatory electrocardiographic monitoring beyond 24 to 48 hours can improve the detection of arrhythmias, lead-based Holter monitors might be limited by patient compliance and other factors.
These researchers, therefore, evaluated compliance, analyzable signal time, interval to arrhythmia detection, and diagnostic yield of the Zio Patch, a novel leadless, electrocardiographic monitoring device in 26, consecutive patients. The mean wear time was 7. Among the patients with detected arrhythmias Compared with the first 48 hours of monitoring, the overall diagnostic yield was greater when data from the entire Zio Patch wear duration were included for any arrhythmia For paroxysmal atrial fibrillation AF , the mean interval to the first detection of AF was inversely proportional to the total AF burden, with an increasing proportion occurring after 48 hours The authors concluded that extended monitoring with the Zio Patch for less than or equal to 14 days is feasible, with high patient compliance, a high analyzable signal time, and an incremental diagnostic yield beyond 48 hours for all arrhythmia types.
These findings could have significant implications for device selection, monitoring duration, and care pathways for arrhythmia evaluation and AF surveillance. Higgins stated that a number of substantial improvements to the year old concept of the Holter monitor have recently been developed.
Its ease-of-use, which enables optimal long-term monitoring, has been established in the ambulatory setting, although some insurance carriers have been reluctant to reimburse appropriately for this advance, an issue characteristic of other heart monitors, treated as 'loss-leaders'. In this article, in addition to discussing possible reasons for this reluctance, a novel model for direct-to-consumer marketing of heart monitoring, outside of the traditional health insurance reimbursement model, is also presented.
Additional current and future advances in heart rhythm recording are also discussed. Such potentially revolutionary opportunities have only recently become possible as a result of technologic advances. The Center for Medicare and Medicaid Services CMS has determined that an ambulatory cardiac monitoring device or service is eligible for Medicare coverage only if it can be placed into the following categories:. The CMS has determined that an ambulatory cardiac monitoring device or service is not covered if it does not fit into these categories.
Evaluation and Treatment of Sick Sinus Syndrome
Hanke et al noted that hr Holter monitoring 24HM is commonly used to assess cardiac rhythm after surgical therapy of atrial fibrillation AF. However, this "snapshot" documentation leaves a considerable diagnostic window and only stores short-time cardiac rhythm episodes. To improve accuracy of rhythm surveillance after surgical ablation therapy and to compare continuous heart rhythm surveillance versus 24HM follow-up intra-individually, these investigators evaluated a novel implantable continuous cardiac rhythm monitoring IMD device Reveal XT , Medtronic Inc.
A total of 45 cardiac surgical patients male 37, mean age of Mean follow-up was 8. The authors concluded that for "real-life" cardiac rhythm documentation, continuous heart rhythm surveillance instead of any conventional 24HM follow-up strategy is necessary. This is particularly important for further judgment of ablation techniques, devices as well as anti-coagulation and anti-arrhythmic therapy.
Hindricks et al quantified the performance of the first implantable leadless cardiac monitor ICM with dedicated AF detection capabilities. The sensitivity, specificity, positive-predictive value, and NPV for identifying patients with any AF were The authors concluded that in this ICM validation study, the dedicated AF detection algorithm reliably detected the presence or absence of AF and the AF burden was accurately quantified. Ip et al examined the outcomes of surgical ablation and post-ablation AF surveillance with a leadless ICM.
A total of 45 patients with drug-refractory paroxysmal or persistent AF underwent video-assisted epicardial ablation using a bipolar radiofrequency clamp.
AF recurrence was defined as greater than or equal to 1 AF episode with a duration of greater than or equal to 30 s. The device-stored data were down-loaded weekly over the internet, and all transmitted events were reviewed. Recurrence of AF was highest in first 4 weeks and substantially decreased 6 months post-ablation. The authors concluded that ICM provides an objective measure of AF ablation success and may be useful in making clinical decisions.
It is in a thin case with 2 electrodes that snaps onto the back of an iPhone 4 or 5. To obtain an electrocardiogram ECG recording, the patient just holds the device while pressing fingers from each hand onto the electrodes. The device can also obtain an ECG from the patient's chest. The AliveCor ECG iPhone application can record rhythm strips of any duration to be stored on the phone and uploaded securely for later analysis, sharing, or printing through AliveCor's website. The AliveCor Heart Monitor will operate for about hours on a 3.
However, there is currently a lack of evidence to support the clinical value of the AliveCor Heart Monitor. According to the company, research studies are currently in progress to explore effectiveness of the AliveCor Heart Monitor in the following areas:. The median interval to NDAF detection in these higher risk patients was 72 days interquartile range: 13 to Whether patients with CHADS2 risk factors but without a history of AF might benefit from implantable monitors for the selection and administration of anti-coagulation for primary stroke prevention merits additional investigation.
A cohort study was reported of 51 patients in whom ILRs were implanted for the investigation of ischemic stroke for which no cause had been found cryptogenic following appropriate vascular and cardiac imaging and at least 24 hours of cardiac rhythm monitoring.
Age of patients ranged from 17 to 73 median of 52 years. Of the 30 patients with a shunt investigation, 22 had a patent foramen ovale Atrial fibrillation was identified in 13 The median range of monitoring prior to AF detection was 48 0 to days. Predictors of AF were identified, which may help to target investigations. They stated that ILRs may have a central role in the future in the investigation of patients with unexplained stroke.
The authors concluded that these findings showed that many but not all patients develop new AF within the first 4 months of flutter ablation. The median time to detection of AF was 7 days. The majority of patients with paroxysmal AF were asymptomatic during the fleeting episodes. Other reports have noted that the detection rate of paroxysmal AF can be increased with longer duration of cardiac monitoring, and that precursors of AF such as frequent premature atrial contractions may predict those harboring paroxysmal AF.
Patients 40 years of age or older with no evidence of atrial fibrillation during at least 24 hours of ECG monitoring underwent randomization within 90 days after the index event. The primary end-point was the time to first detection of atrial fibrillation lasting greater than 30 seconds within 6 months. Among the secondary end-points was the time to first detection of atrial fibrillation within 12 months. Data were analyzed according to the intention-to-treat principle.
By 6 months, atrial fibrillation had been detected in 8. By 12 months, atrial fibrillation had been detected in The authors concluded that ECG monitoring with an ICM was superior to conventional follow-up for detecting atrial fibrillation after cryptogenic stroke. In the EMBRACE trial, Gladstone et al randomly assigned patients 55 years of age or older, without known atrial fibrillation, who had had a cryptogenic ischemic stroke or TIA within the previous 6 months cause undetermined after standard tests, including hour electrocardiography [ECG] , to undergo additional noninvasive ambulatory ECG monitoring with either a day event-triggered recorder intervention group or a conventional hour monitor control group.
The primary outcome was newly detected atrial fibrillation lasting 30 seconds or longer within 90 days after randomization. Secondary outcomes included episodes of atrial fibrillation lasting 2. Atrial fibrillation lasting 30 seconds or longer was detected in 45 of patients Atrial fibrillation lasting 2. By 90 days, oral anti-coagulant therapy had been prescribed for more patients in the intervention group than in the control group 52 of patients [ The investigators concluded that, among patients with a recent cryptogenic stroke or TIA who were 55 years of age or older, paroxysmal atrial fibrillation was common.
Even after long-term follow-up involving 3 years of continuous rhythm monitoring in the CRYSTAL AF trial, less than one third of the patients had evidence of atrial fibrillation. We need to identify additional sources of embolism and better markers of known stroke mechanisms such as nonobstructive atherosclerosis. Second, we need more evidence to guide therapy for subclinical atrial fibrillation. Randomized trials of antithrombotic therapy have involved patients with a sufficient burden of atrial fibrillation to allow its recognition without prolonged rhythm monitoring.
Whether the proven benefit of anticoagulation in this population extends to patients with subclinical atrial fibrillation must be answered in future trials. The weight of current evidence suggests that subclinical atrial fibrillation is a modifiable risk factor for stroke recurrence, and its presence should be thoroughly ruled out in this high-risk population. Therefore, most patients with cryptogenic stroke or transient ischemic attack should undergo at least several weeks of rhythm monitoring. Relatively inexpensive external loop recorders, such as those used in the EMBRACE trial, will probably be cost-effective; the value of more expensive implantable loop recorders is less clear.
Furthermore, the detection of subclinical atrial fibrillation in these patients should generally prompt a switch from antiplatelet to anticoagulant therapy. At the least, patients should be followed closely in order to detect progression to clinically apparent atrial fibrillation, in which case the evidence unambiguously supports anticoagulant therapy for the secondary prevention of stroke.
It differs from other implantables as it does not have leads going to the heart. An external magnet can also be positioned over the implanted device to record ECG data when symptoms are experienced. The mobile patient management system is a monitoring device designed for detection of cardiac arrhythmias. These devices differ from other ECG devices as they may also monitor activity, body fluid status, body temperature posture and respiratory rate. The ViSi Mobile Monitoring System is intended for single or multi-parameter vital sign monitoring of adults.
It measures ECG three or five leads , heart rate, respiration rate, noninvasive blood pressure, noninvasive monitoring of oxygen saturation SpO2 , pulse rate and skin temperature. Self-monitoring ECG technologies, which may be obtained without physician prescription include, but are not limited to, software applications for smartphones and other electronic devices suggested to monitor ECG, heart rate, oxygen saturation, respiratory rate, etc. These devices may be attached to a finger, ear lobe or other body part.
Ciconte and colleagues noted that continuous rhythm monitoring is valuable for adequate AF management in the clinical setting. Subcutaneous leadless ICMs yield an improved AF detection, overcoming the intrinsic limitations of the currently available external recording systems, thus resulting in a more accurate patient treatment. These investigators evaluated the detection performance of a novel 3-vector ICM device equipped with a dedicated AF algorithm.
A total of 66 patients KG, Berlin, Germany , were enrolled. External hour ECG Holter was performed 4 weeks after the device implantation. The authors concluded that continuous monitoring using this novel device, equipped with a dedicated detection algorithm, yielded an accurate and reliable detection of AF episodes. Chung and Guise evaluated the feasibility of AliveCor tracings for QTC assessment in patients receiving dofetilide.
Cardiac Event Monitors - Medical Clinical Policy Bulletins | Aetna
A total of 5 patients with persistent AF underwent the 2-handed measurement mimicks Lead I. With only one exception, Eberhardt was diagnosing lesions less than 3 cm in diameter and in our trial lesions were almost 1 cm larger in average. Complication rates in both trial are also comparable, 1. Kokkonouzis et a 21 published one of the most recent trials on usefulness of radial EBUS in diagnosis of PPL in general hospital setting. Authors performed retrospective evaluation of 40 patients. Diagnostic yield was But success rate of these trials is within the confidence interval recorded in our study.
Study published by Tay et al 23 identified lesion size, malignancy status and distance from hilum as important and significant predictors of EBUS visualization yield. The fact that we included only patients with visualized lesions and that majority of patients had lung cancer could influence high overall diagnostic yield and sensitivity of EBUS guided sampling techniques in our trial.
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These high sensitivities are close to the confidence intervals we reported One of the largest retrospective trials was published in by Fuso et al The authors evaluated patients with average size of the lesion 3. In our trial success rate for malignant disease was not extrapolated from merged results, however sensitivity of EBUs guided TBB was Again, our results are calculated according to protocol which included only visualized lesions.
One of the most recent trials compared diagnostic performance of radial EBUS and CT guided percutaneous core biopsies Even though the difference is not statistically significant sensitivity is obviously lower. However, CT guided biopsy had significantly higher diagnostic yield for lesions less than 2 cm in diameter. The only foulness of CT-guided biopsy is significantly higher rate of pneumothorax. Lower complication rate in terms of pneumothorax might go in favor of radial EBUS, as demonstrated by this trial.
We reported only one pneumothorax in our trial. This trial conducted on patients with suspected lung cancer concluded that radial EBUS guided techniques do not increase detection rate for cancer in PPL when bronchoscopy is performed by bronchoscopists at all levels of expertise. Even though diagnostic effectiveness of EBUS guided sampling is confirmed by majority of trials and recent meta-analyses, further studies are needed to confirm its role in the evaluation of PPL.
High sensitivity and specificity reported in this trial are comparable to previously published results. Suction catheter biopsy could be regarded as valuable technique, simple and readily available for routine use in EBUS guided bronchoscopic diagnosis of peripheral lesions. The study was supported by the grant of the Serbian Ministry of Science and Technology, grant number National Center for Biotechnology Information , U.
Journal List J Cancer v. J Cancer. Published online Jan 1. Bojan Zaric 1. Vladimir Stojsic 1. Vladimir Carapic 1. Tomi Kovacevic 1. Goran Stojanovic 1. Milana Panjkovic 1. Ioannis Kioumis 3. Kaid Darwiche 2. Konstantinos Zarogoulidis 3. Grigoris Stratakos 4. Drosos Tsavlis 3. Wolfgang Hohenforst-Schmidt 5. Georgia Pitsiou 3. Athanasios Zissimopoulos 6. Nikos Sachpekidis 7. Ilias Karapantzos 8.
Chrysanthi Karapantzou 8. Paul Zarogoulidis 3. Branislav Perin 1.
Author information Article notes Copyright and License information Disclaimer. D, Ph. Fax: ; Mobile: ; E-mail: moc. Conflict of Interest: The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript. Received Jun 29; Accepted Aug Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. This article has been cited by other articles in PMC. Keywords: bronchoscopy, endobronchial ultrasound, EBUS, interventional pulmonology, lung cancer, peripheral pulmonary lesion.
Introduction There is an ongoing debate about the most efficient diagnostic procedure for histological or cytological diagnosis of peripheral lung lesions PPL. Inclusion criteria Inclusion criteria for enrollment in the study were: age over 18 years, radiological proof of peripheral lung opacity, indication for bronchoscopy and peripheral lesion visualized by EBUS. Open in a separate window.
Figure 1. Figure 2. Figure 3. Biopsy sample, tissue fragments can be seen at the flour of the bottle. Statistical analysis Descriptive statistics were generated for all study variables, including mean and standard deviation SD for continuous variables and relative frequencies for categorical variables. Results There were patients, Table 1 Patient characteristics.