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PubMed2002

Exercise-electrocardiography and/or pharmacological stress echocardiography for non-invasive risk stratification early after uncomplicated myocardial infarction. A prospective international large scale multicentre study.

AIMS: The aim of the present study was to assess the relative prognostic value of clinical variables, the exercise electrocardiography test and the pharmacological stress echocardiography test either with dipyridamole or dobutamine early after a first uncomplicated acute myocardial infarction in a large, multicentre, prospective study. METHODS AND RESULTS: Seven hundred and fifty-nine in-hospital patients (age=56+/-10 years) with a recent and first clinical uncomplicated myocardial infarction, with baseline echocardiographic findings of satisfactory quality, an interpretable ECG and able to exercise underwent a resting 2D echocardiogram, a pharmacological stress test with either dipyridamole or dobutamine and an exercise electrocardiography test at a mean of 10 days from the infarction; they were followed-up for a median of 10 months. During the follow-up, there were 13 deaths, 23 non-fatal myocardial infarctions and 59 re-hospitalizations for unstable angina. When all spontaneous events were considered, with multivariate analysis, the difference between the wall motion score index at rest and peak stress (delta wall motion score index), and exercise duration were independent predictors of future spontaneous events (relative risk 7.2; 95% CI=2.73-19.1; P=0.000; relative risk 1.1, 95% CI=1.02-1.18; P=0.008, respectively). Kaplan-Meier survival estimates showed a better outcome for those patients with a negative pharmacological stress echocardiography test compared to patients with low dose positivity (94.7 vs 74.8%, P=0.000). CONCLUSION: Stress echocardiography tests provide stronger information than historical and exercise electrocardiography test variables. Pharmacological echocardiography as well as the exercise ECG is able to predict all spontaneously occurring events when the presence as well as the timing, severity, and extension of stress-induced wall motion abnormalities are considered.

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PubMed1999

Fetoscopic transesophageal electrocardiography and stimulation in fetal sheep: a minimally invasive approach aimed at diagnosis and termination of therapy-refractory supraventricular tachycardias in human fetuses.

BACKGROUND: Therapy-refractory supraventricular tachycardia commonly results in hydrops and death in human fetuses. The purpose of this study in fetal sheep was to assess the feasibility of a minimally invasive fetoscopic approach for fetal transesophageal electrocardiography and stimulation aimed at diagnosis and termination of these tachycardias. METHODS AND RESULTS: We studied a total of 10 fetal sheep (87 to 103 days of gestation; term=145 days). We entered the amniotic cavity using a percutaneous fetoscopic approach and placed various electrophysiology catheters into the fetal esophagus. We recorded the number of animals in which fetoscopic transesophageal electrocardiography and stimulation were successful and assessed pacing success and thresholds for different catheters. In addition, we monitored for potential adverse effects from stimulation and for other complications of the operation. Recording of transesophageal electrocardiograms was successful in all fetal sheep. Capture during stimulation was successfully documented by additional fetal bipolar surface electrocardiograms in 7 fetuses. In fetuses in which fetal surface electrocardiograms were not recorded, pacing stimulus artifacts interfered with documentation of capture. Although stimulation thresholds were high, the maternal rhythm was not affected by fetal stimulation. CONCLUSIONS: Fetoscopic fetal transesophageal electrocardiography and stimulation are feasible in fetal sheep. This minimally invasive approach might have the potential to improve diagnosis and management of therapy-refractory supraventricular tachycardias in human fetuses.

Animals↗

PubMed1981

Spatial electrocardiography.

Spatial electrocardiography can express the spatial characteristics of electromotive forces of the heart quantiatively. The pattern of the sequential changes of these spatial characteristics of the cardiac vectors also provides important diagnostic informations. Accordingly, spatial electrocardiography is considered to be useful in clinical cardiology in association with conventional electrocardiography and vectorcardiography.

Humans↗

PubMed2002

High resolution electrocardiography.

Over the past decade, significant advances were made in the research, diagnosis, and treatment of cardiovascular diseases. Such progress was in every sphere of cardiology that includes non-invasive, minimally invasive, and invasive technologies. Interpretive electrocardiography, cardiac pacemakers, cardiac stents, and angioplasty are some areas where the progress has been significant. Non-invasive methods of diagnosis of cardiac disorders involve digital recording of cardiac signals at the body surface (chest) and subsequent computerized analysis. Such methods and instruments provide a vital first step to the diagnosis of the heart without involving surgical procedures. One such non-invasive field is High Resolution Electrocardiography (HRECG). A high-resolution electrocardiogram detects very low amplitude signals in the ventricles called 'Late Potentials' in patients with abnormal heart conditions. A standard electrocardiogram cannot detect these signals. The presence of late potentials is widely accepted to have prognostic significance in patients after Acute Myocardial Infarction (AMI) High Resolution Electrocardiography enhances the diagnostic capabilities of ECGs. This article describes the principles involved in HRECG and the techniques that are employed to derive such superior diagnostic capabilities. The use of these techniques may lead to more discoveries in the causes of cardiac disorders and improved drug discoveries to combat such conditions.

Journal Article↗

PubMed1995

Use of signal-averaged electrocardiography for predicting inducible sustained monomorphic ventricular tachycardia in patients with bundle branch block with and without a history of syncope.

The aim of this study was to examine the utility of signal-averaged electrocardiography in relation to inducible sustained monomorphic ventricular tachycardia in patients with bundle branch block. One hundred fourteen patients with bundle branch block underwent signal-averaged electrocardiography in the time domain and programmed ventricular stimulation. Sustained monomorphic ventricular tachycardia was induced in 17 patients. The mean values of the three signal-averaged electrocardiographic variables analyzed differed significantly between the inducible and the noninducible group. The filtered QRS duration showed the most prominent difference between the two groups, and a filtered QRS duration > or = 155 msec had a sensitivity of approximately 80%, a specificity of 60%, and a total predictive value of 65%. In the subgroup of patients with syncope, a combination of these criteria with a history of coronary artery disease had a sensitivity of 100% and a specificity of 90%.

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PubMed1995

Signal-averaged electrocardiography in myotonic dystrophy.

We performed signal-averaged electrocardiography and 24-h ambulatory electrocardiographic monitoring in 53 patients with myotonic dystrophy to determine the incidence and clinical significance of ventricular late potentials. Patients were followed up for a mean period of 31 +/- 17 months (range 11-68 months). At entry, none of the patients had bundle branch block on 12-lead electrocardiogram and none had wall motion abnormalities on routine echocardiogram. Also, no patient had history of syncope or clinical evidence of ischemic heart disease or a documented sustained ventricular tachycardia. A group of 47 healthy subjects matched for age and sex also underwent signal-averaged electrocardiography for comparison with the patient group. Late potentials were diagnosed in the presence of at least two of the following measures: duration of the filtered QRS > 114 ms, root-mean-square voltage of the terminal 40 ms of the filtered QRS < 20 microV, and duration of the low-amplitude (< 40 microV) signals of terminal filtered QRS > 38 ms. Late potentials were more frequent in patients than in controls: 18 of the 53 patients (34%) showed late potentials compared with four of the 47 controls (8.5%) (P < 0.01). In 45 patients (85%) no ventricular ectopy (40 cases) or infrequent premature ventricular complexes (five cases) were detected on Holter monitoring. Complex ventricular arrhythmias were traced in the remaining eight patients. These were six of the 18 patients with, and two of the 45 patients without late potentials (33% vs. 6%, respectively; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1995

Signal-averaged electrocardiography and ventricular tachycardia as predictors of mortality after acute myocardial infarction in elderly patients.

Signal-averaged electrocardiography and 24-hour ambulatory electrocardiographic monitoring were performed in 121 elderly patients > 6 months after acute myocardial infarction. All patients had asymptomatic complex ventricular arrhythmias and a left ventricular ejection fraction > or = 40%. Rates of sudden, cardiac, and total death were compared between groups with and without nonsustained ventricular tachycardia and between normal and abnormal signal-averaged electrocardiographic studies. The prevalence of an abnormal signal-averaged electrocardiographic study was 36%. Thirty-seven percent of the patients had nonsustained ventricular tachycardia, and the remaining patients had complex ventricular arrhythmias other than ventricular tachycardia. There were 27 sudden and 48 total cardiac deaths, and 66 deaths from all causes during a mean follow-up period of 30 months. Kaplan-Meier survival analysis showed a lower rate of sudden and cardiac death in the group without nonsustained ventricular tachycardia. Although there was a trend toward a lower rate of sudden death in patients with a normal signal-averaged electrocardiogram, there was no statistical difference in the rates of sudden, total cardiac, or total death between patients with normal or abnormal studies. The negative predictive value of having neither an abnormal signal-averaged electrocardiogram nor nonsustained ventricular tachycardia was 94% for sudden death. In elderly patients with complex ventricular arrhythmias and ejection fraction > or = 40% at least 6 months after an acute myocardial infarction, presence of nonsustained ventricular tachycardia predicted a higher rate of sudden and cardiac death. Signal-averaged electrocardiography alone was not predictive.

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PubMed2002

Longitudinal evaluation of anthracycline cardiotoxicity by signal-averaged electrocardiography in children with cancer.

BACKGROUND: The aim of the present study was to investigate the detection of anthracycline cardiotoxicity by signal-averaged electrocardiography (SAE) in children with cancer. METHODS: There were 29 patients with a cumulative anthracycline (ATC) dose of 75-600 mg/m2. None of them had congestive heart failure. Patients underwent SAE just before (detection of chronic cardiotoxicity) and just after (detection of acute cardiotoxicity) ATC therapy. Echocardiography and Holter electrocardiography were performed at the same time. The rates of abnormal SAE, echocardiography, and electrocardiogram findings were calculated and compared for every 100 mg/m2 of ATC. RESULTS: The SAE showed a significantly higher detection rate for acute cardiotoxicity was at a cumulative ATC dose of less than 400 mg/m2 when compared with other methods (P < 0.05). The lowest dose at which acute cardiotoxicity was detected by SAE was 117.3 mg/m2. The detection of chronic cardiotoxicity by SAE was significantly higher at a cumulative ATC dose of 100-400 mg/m2 when compared with other methods (P < 0.05), and the lowest value showing toxicity was 373.3 mg/m2. The lowest ATC dose causing chronic cardiotoxicity was significantly lower in patients less than 2-years-old (120.0 +/- 28.3 mg/m2) than in the other age groups (P < 0.05). CONCLUSIONS: Acute and chronic ATC cardiotoxicity were detected by SAE at lower cumulative doses compared with other methods. The technique of SAE was a potentially useful method for detection of cardiotoxicity among those investigated and it provides useful information on subclinical cardiac dysfunction in patients receiving ATC therapy.

Anthracyclines↗

PubMed2026

Development of Electrocardiography Standards for Evaluating Myocardial Infarction and Ischemia-Reperfusion Injury in Mice.

BACKGROUND: Acute and chronic heart failure secondary to myocardial infarction (MI) and cardiac ischemia-reperfusion injury (IRI) are leading causes of death in ischemic heart disease. A mouse model is indispensable for investigating MI and IRI, and the development of reliable mouse MI and IRI models is essential for advancing research in this field. The clear early diagnostic criteria for confirming successful induction of MI and IRI in mice remain lacking. METHODS: Adult C57BL/6J background mice underwent left anterior descending coronary artery ligation to induce acute MI, or ligation followed by reperfusion to induce IRI. The success of the MI and IRI model establishment was confirmed by 2,3,5-triphenyltetrazolium chloride staining and echocardiography. Electrocardiography was used to monitor the electric activity in the mice. CONCLUSIONS: Electrocardiography demonstrated that ST-segment elevation in ECG lead II and corrected QTc interval prolongation at 30 minutes following left anterior descending ligation as 2 key early indicators of successful MI. Echocardiography analysis revealed that the magnitude of ST-segment elevation strongly correlated with the left anterior descending ligation site, where a more proximal ligation produced a greater ST-segment elevation amplitude and more severe ischemia. In IRI models, ST-segment elevation typically resolved and returned to baseline within 20 minutes of reperfusion. This study developed quantifiable early diagnostic criteria for successful MI and IRI induction based on characteristic ECG changes. These quantifiable ECG parameters provide early diagnostic standards that can significantly streamline and optimize modeling procedures.

Animals↗

PubMed1995

[Complementary tests: conventional and Holter electrocardiography].

Arterial hypertension can cause left ventricular hypertrophy and consequent hypertensive cardiopathy, a condition that is associated with the development of heart failure, arrhythmia and ischemia. Electrocardiography is the oldest and simplest method for diagnosing left ventricular hypertrophy: nevertheless, though established electrocardiographic criteria are highly specific, their sensitivity is low, far below that of echocardiography. There are, however, new electrocardiographic criteria with improved sensitivity; moreover, the presence of electrocardiographic signs of hypertrophy in a hypertensive patient makes a diagnosis of hypertrophy highly probable. The Holter monitor has many applications in the assessment of hypertensive patients. It identifies auricular and ventricular arrhythmias in terms of anatomical patterns, and can be used to evaluate drug response and detect the presence of silent ischemia and sudden death. In conclusion, electrocardiography is an easily accessible tool and a highly useful one in the management of hypertensive patients, in spite of its limitations.

Electrocardiography↗

PubMed1979

Extent and severity of coronary heart disease. Determinations by thallous chloride Tl 201 myocardial perfusion scanning and comparison with stress electrocardiography.

Rest and exercise ECGs are the most widely used "noninvasive" tests for detecting coronary heart disease, but their sensitivity and specificity are suboptimal. Therefore, the diagnostic value of myocardial perfusion scanning using thallous chloride Tl 201 during rest and stress electrocardiography was examined in 95 patients with a chest discomfort syndrome. Overall, thallous chloride Tl 201 perfusion scanning had a sensitivity of 75% and a specificity of 91% for coronary heart disease compared with 56% sensitivity and 86% specificity with exercise-induced ST segment depression on the ECG. Combining rest and stress ECGs resulted in a sensitivity of 71%. In patients with coronary heart disease, perfusion scanning had a sensitivity of 93% for asynergy compared with 58% for exercise-induced ECG ST depression. Rest and stress myocardial perfusion scanning with thallous chloride Tl 201 provides improved sensitivity with good specificity in the diagnosis of coronary heart disease compared with exercise electrocardiography alone.

Arrhythmias, Cardiac↗

PubMed1994

Right atrial electrocardiography: a technique for the placement of central venous catheters for chemotherapy or intravenous nutrition.

Central venous catheters used for chemotherapy are usually sited so that the catheter tip lies in the superior vena cava. This study evaluated right atrial electrocardiography as a method of accurately placing the catheter tip in 34 patients over a period of 22 months. An electrocardiograph adaptor was connected to the catheter and the tip advanced into a central vein until a biphasic P wave was identified. In 31 of 34 patients the characteristic P wave changes were observed and the position of the catheter tip confirmed by screening to be in the superior vena cava. Right atrial electrocardiography is an accurate, reliable and rapid method of positioning the tip of a central venous catheter, and avoids or reduces exposure to radiation.

Catheterization, Central Venous↗

PubMed1986

Studies on ergometer exercise testing. II. Effect of previous myocardial infarction, digoxin, and beta-blockade on exercise electrocardiography.

The results of exercise electrocardiography were studied in a random sample of 317 subjects with clinical suspicion of coronary artery disease. In 278 patients with coronary artery disease the rate of false negative tests was 18% with and 12% without previous myocardial infarction. If ST elevation was considered a negative response, the corresponding values were 25% and 13%, respectively, p less than 0.01. The greatest prevalence of negative tests was seen after anterior myocardial infarction: 27% or 42% when ST elevation was not included into positive responses. The sensitivity of exercise-induced ST depression for the presence of multivessel disease was lower after anterior infarction (67%) than in other patients with previous infarction (86%), p less than 0.01. The corresponding specificities were 71% and 22%, respectively, p less than 0.005. If ST elevation was included into positive responses these differences were abolished. In subjects without myocardial infarction the sensitivity was 89% and specificity 43%. Digitalized patients had somewhat higher sensitivity in the exercise electrocardiogram than those without digoxin, 90% vs. 81% (p less than 0.05), but the difference was not seen with exclusion of ST elevation. The specificity was not influenced by digitalis. beta-blockade had no effect on the sensitivity or specificity, but the prevalence of postexercise ST evolution was lower with (11%) than without (30%) beta-blockade. The prevalence of slowly ascending ST depression was reduced by three factors: the presence of digitalis in patients without previous myocardial infarction, infarction itself, and the extent of coronary artery disease. We conclude that exercise electrocardiography has only a limited value in prediction of multivessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1989

Signal-averaged electrocardiography and the significance of late potentials in patients with "idiopathic" ventricular tachycardia: a review.

High-frequency, low-amplitude electrical activity during and in continuation with the ventricular electrogram in sinus rhythm is now accepted as an indirect marker for reentrant pathways in ventricular muscle. Because the amplitude of these signals is low, much effort has recently been directed toward finding methods of recording these noninvasively. This essentially involves averaging the electrocardiogram, amplifying it, and filtering out the low frequency and nonrepetitive signals. This review discusses the methods presently available for signal-averaged electrocardiography and their background. The clinical application of signal-averaged electrocardiograms in patients with or suspected to have ventricular tachycardia is summarized. Data regarding the incidence of abnormal signal-averaged electrocardiography in patients with "idiopathic" ventricular tachycardia compared with normal subjects and patients with ventricular tachycardia related to ischemic heart disease are presented.

Action Potentials↗

PubMed1993

Bronchial electrocardiography to determine left or right main bronchial placement of an endotracheal suction catheter tip.

OBJECTIVE: To assess the utility of a blue lined angle tipped and electrode tipped catheter, to guide left and right main bronchus cannulation. DESIGN: A prospective study. SETTING: An 11-bed general intensive care unit in a 900-bed teaching hospital. PATIENTS: 50 intubated intensive care patients, in sinus rhythm with normal P and QRS mean frontal axis, who required endobronchial suctioning for routine respiratory management. INTERVENTIONS: Endobronchial electrocardiography was used to position a blue lined angle tipped and electrode tipped suction catheter into the right and left main bronchi. RESULTS: Selective cannulation of the left main bronchi was determined by observing a biphasic or inverted P wave in 42 patients, or biphasic or inverted QRS complex in 31 patients. In 8 patients in whom no changes in the ECG were found, bronchoscopic placement of an ECG electrode into the left main bronchus demonstrated a biphasic or inverted P wave in 8 patients and a biphasic QRS complex in 3 patients, confirming the failure to cannulate the left main bronchus in these 8 patients. CONCLUSIONS: Using a blue lined, angle tipped and electrode tipped catheter for endotracheal suctioning, endobronchial electrocardiography may be a simple method to signal left or right main bronchus cannulation.

Arrhythmias, Cardiac↗

PubMedDate not supplied

Well-posed formulation of the inverse problem of electrocardiography.

It has long been speculated that incorporation of available time constraints into the inverse electrocardiography problem could improve the accuracy of maps of epicardial potential or activation reconstructed from body surface potential measurements. However, all prior formulations of this problem have remained ill-posed, and the best way to utilize these constraints has been unclear. By making proper use of the timing information, we show that the inverse electrocardiography problem (for calculation of ventricular surface activation isochrones) is formally well-posed under anisotropic bidomain conditions and the assumption that ventricular muscle action potential phase 0 is a step discontinuity. In practical terms, this implies that non-regularized stable activation map solutions are possible if correlates of derived body surface potential derivative discontinuity times can be identified from the noisy analog signals, and only a small number of ventricular surface activation function extrema occur during a unit of time resolution defined by phase zero duration over the spatial extent of a bidomain point. We include a quasi-realistic numerical example illustrating the ease with which the extrema of the endocardial and epicardial activation maps are computed via Jump Maps derived from body surface potentials (this being the crucial step in rendering images of ventricular surface activation in this approach). The efficient signal processing algorithm used to accomplish this task is well suited to the setting of multiple extrema occurring during overlapping phase zero time intervals.

Algorithms↗

PubMedDate not supplied

The role of cardiac troponin I in determining the necessity for exercise electrocardiography in low risk patients with chest pain.

BACKGROUND: Assessment of non-cardiac chest pain places a considerable burden on healthcare resources. The current practice of serial electrocardiographs (ECGs), serum creatinine phosphokinase and by pre-discharge exercise electrocardiography gives an average in-hospital stay of 3.7 days. AIMS: This study assess the use of a sensitive assay for cardiac troponin I (cTnI) to identify a low risk group for whom exercise ECG may not be indicated. METHOD: Ninety-five patients with acute chest pain and with peak cTnI < 0.1 ng/ml and a non-diagnostic resting ECG were studied. Patients were divided into two groups. Group one had normal range cTnI (< 0.03 ng/ml). Group two had minimal elevation of cTnI (0.03-0.099 ng/ml). Average follow-up was 172 days. RESULTS: Nineteen patients had minimal elevation in cTnI of whom five developed significant ST shift on exercise and five had adverse events. No patient with a normal range cTnI had a positive stress test and none suffered an adverse event (p < 0.001). CONCLUSION: CTnI in the normal range can identify patients with acute chest pain who have a negligible event rate and for whom exercise electrocardiography is not required.

Chest Pain↗

PubMed1986

Prospective evaluation of the severity of coronary artery disease with exercise radionuclide angiography and electrocardiography.

To evaluate the utility of exercise radionuclide angiography (RNA) and electrocardiography in assessing the severity of coronary artery disease (CAD), 185 patients undergoing coronary angiography were studied prospectively. To avoid work-up bias and to provide an appropriate control group, all patients were simultaneously scheduled for exercise RNA and electrocardiography and for coronary arteriography. All test results were interpreted blinded to other data. Of multiple exercise variables analyzed by stepwise linear discriminant analysis, the independent predictors of disease severity were exercise ejection fraction, ST segment change, and maximum heart rate. These three variables were used to create a set of four equations that determine probabilities of zero, one-, two-, or three-vessel disease (VD). The noninvasive estimate of number of VD in each patient was compared to the angiographic result. Patients without significant CAD were classified correctly 71% of the time, while those with three-VD were predicted correctly in 80%. Fully 90% of patients with predicted three-VD had two- or 3-VD. Conversely, 84% of patients predicted to have zero VD had zero or one-VD. Thus the combined use of exercise RNA and ECG data permits assessment of the presence and severity of CAD.

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