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Reciprocal ST change in acute myocardial infarction: assessment by electrocardiography and echocardiography.

To evaluate the incidence, time course and significance of reciprocal change, 25 consecutive patients admitted with their first acute transmural myocardial infarction were studied with serial electrocardiography and two-dimensional echocardiography. Reciprocal change was noted in all patients with inferior infarction (mean maximal ST segment depression 3.53 +/- 1.97 mm) and 70% of patients with anterior infarction (mean maximal ST depression 1.45 +/- 0.8 mm, p = 0.001). When initially present, reciprocal change had resolved within 24 hours in 59% of patients. The sum of reciprocal ST depression correlated with the sum of ST elevation in anterior (r = 0.92, p less than 0.001) and inferior (r = 0.55, p = 0.035) infarction, and this relation persisted when maximal ST depression and elevation were considered. Echocardiographic evidence of contraction abnormalities in areas of the left ventricle remote from the infarction was seen in 45% of patients. However, its presence did not correlate with the presence of reciprocal change. Although reciprocal change progressively diminished on serial electrocardiograms (maximal ST depression 2.73 +/- 1.77 mm at 19 hours after onset of symptoms; 1.0 +/- 0.92 mm at 2 to 3 days; and 0.22 +/- 0.26 mm at 7 to 10 days; p less than 0.05), the corresponding serial echocardiograms showed no change in the function of the remote wall (remote wall motion index 1.87 +/- 0.65, 1.81 +/- 0.62, 1.86 +/- 0.47, respectively, p = NS). These data, therefore, do not support the hypothesis that reciprocal ST depressions during early acute transmural myocardial infarction reflect remote ischemia. Rather, these changes are influenced by factors determining the degree of acute ST elevation, previously shown to include infarct size, shape, location, transmurality and duration.

Adult↗

Regional myocardial dysfunction during coronary angioplasty: evaluation by two-dimensional echocardiography and 12 lead electrocardiography.

Balloon inflation performed during percutaneous transluminal coronary angioplasty causes transient total occlusion of the coronary artery and thus provides a model for evaluation of the regional myocardial responses to transient ischemia. Twenty patients with normal left ventricular function undergoing angioplasty of isolated stenosis of the proximal left anterior descending coronary artery were studied. In group A (14 patients) analysis of one inflation-deflation sequence per patient was performed. Group B (six patients) had multiple (greater than 5) inflations; the first and last sequences were analyzed. Assessment included continuous two-dimensional echocardiography with computerized quantitative analysis of regional left ventricular wall motion, and continuous 12 lead electrocardiographic recordings. The mean duration of inflation in group A was 62 +/- 6 seconds (mean +/- SD). The onset of regional left ventricular dysfunction was 12 +/- 5 seconds after inflation. Profound dysfunction was noted in all patients. After 60 seconds of balloon occlusion of the coronary artery, 29% of patients had severe hypokinesia of the ischemic region and 71% had akinesia or dyskinesia. With deflation there was prompt recovery of regional function, with full recovery at 43 +/- 17 seconds. Comparison of data from first and last inflations in group B revealed no significant differences in time to onset of dysfunction, magnitude of dysfunction or time to complete recovery of function. The onset of ischemic electrocardiographic changes lagged behind the onset of wall motion abnormalities, with only 64% of patients showing evidence of ischemia on 12 lead electrocardiograms at 20 seconds of inflation. After 60 seconds, 86% had ischemia detectable by electrocardiography. Thus, balloon inflation during coronary angioplasty leads to profound but reversible regional left ventricular dysfunction. Repeated occlusions of the coronary artery during angioplasty do not have a cumulative ischemic effect. It may be hazardous to apply these findings to patients who have underlying major left ventricular dysfunction and in whom the reversibility of dysfunction and lack of cumulative ischemic effect may not be assured.

Adult↗

Electrocardiography.

Electrocardiography is currently the most accurate method of documenting cardiac arrhythmias and conduction abnormalities. This article discusses techniques of recording electrocardiograms and the systematic evaluation of electrocardiograms to ensure accurate interpretation.

Animals↗

Exercise echocardiography versus exercise electrocardiography in the diagnosis of coronary artery disease in hypertension.

In hypertension, coronary artery disease (CAD) can be overestimated by stress electrocardiography (ECG) and scintigraphy due to frequent false-positive results. Exercise tests are also limited by an excessive blood pressure increase, and pharmacologic pressure normalization decreases the accuracy of the test. The aim of this study was to assess the accuracy of exercise echocardiography as an alternative test for CAD detection in hypertension, both before and after adequate blood pressure control. We studied 59 hypertensive and 59 normotensive patients undergoing coronary angiography for chest pain. Upright bicycle exercise ECG and echocardiographic tests were performed in each group in the absence of therapy; in hypertensives, the tests were repeated a day apart after blood pressure normalization with sublingual nifedipine. Significant CAD (lumen narrowing >50%) was detected in 22 hypertensive and 41 normotensive patients. In the two groups, sensitivity, specificity, and diagnostic accuracy of exercise echocardiography performed before treatment were not statistically different (95%, 94%, 94% in hypertensives and 82%, 77%, 83% in normotensives, respectively), but were significantly higher than for the exercise ECG test (68%, 70%, and 69%, respectively). After blood pressure lowering, exercise echocardiography sensitivity slightly decreased (91%), whereas specificity (100%) and diagnostic accuracy (96%) did not vary; on the contrary, exercise ECG sensitivity decreased to 45%. Therefore, according to our data, exercise echocardiography can be an accurate test and more reliable than exercise ECG to detect CAD in normotensives as well as in hypertensives. Normalization of blood pressure with nifedipine does not affect its accuracy, but markedly reduces the sensitivity of exercise ECG.

Aged↗

Cost comparison of electrocardiography versus fluoroscopy for central venous line positioning in children.

BACKGROUND: Although most central venous lines in children are positioned using fluoroscopy, electrocardiography (ECG) has been shown to be accurate, and avoids unnecessary radiation exposure. We studied whether ECG may also have cost advantages. STUDY DESIGN: All ports and Hickman/Broviac catheters placed during a 2.5-year period were reviewed. Two surgeons routinely used fluoroscopy, and two used ECG. Costs included surgeon and anesthesia fees, operating room use, and fluoroscopy equipment and personnel. RESULTS: There were 287 cases with sufficient data to be included in the study (167 fluoroscopy and 120 ECG). In the ECG group, 12 (10%) were converted to fluoroscopy because an adequate tracing could not be obtained, but they were kept in the ECG group for data analysis. The groups were similar with regard to age, gender, indication, previous catheters, and intraoperative or postoperative complications. Time for surgical placement of the line was not significantly affected by the positioning technique. Ports placed using ECG were less costly than those placed fluoroscopically ($2,880+/-408 versus $3,595+/-357, p<0.001), and the same was true for tunneled external catheters ($2,249 +/- 435 versus $2,923+/-350, p<0.001). CONCLUSIONS: The ECG technique was less costly than fluoroscopy, despite a 10% conversion rate. At our center, the savings were approximately $700 per procedure. Because operating room time used is similar, the additional cost of fluoroscopy can be attributed to the need for x-ray equipment and personnel.

Anesthesiology↗

Wavelet transform in electrocardiography--data compression.

An application of the wavelet transform to electrocardiography is described in the paper. The transform is used as a first stage of a lossy compression algorithm for efficient coding of rest ECG signals. The proposed technique is based on the decomposition of the ECG signal into a set of basic functions covering the time-frequency domain. Thus, non-stationary character of ECG data is considered. Some of the time-frequency signal components are removed because of their low influence to signal characteristics. Resulting components are efficiently coded by quantization, composition into a sequence of coefficients and compression by a run-length coder and a entropic Huffman coder. The proposed wavelet-based compression algorithm can compress data to average code length about 1 bit/sample. The algorithm can be also implemented to a real-time processing system when wavelet transform is computed by fast linear filters described in the paper.

Acoustics↗

Identification of previously undiagnosed left ventricular systolic dysfunction: community screening using natriuretic peptides and electrocardiography.

AIMS: We examined strategies to improve the positive predictive value of natriuretic peptides in screening for undiagnosed left ventricular systolic dysfunction (LVSD) in the community. METHODS AND RESULTS: The value of B-type(BNP), N-terminal proB-type (N-BNP) and N-terminal proAtrial(N-ANP) natriuretic peptides was prospectively assessed in 1360 subjects (45-80 years) together with echocardiography and electrocardiography. Seventeen individuals had definite and 13 had borderline, LVSD. Receiver-operating-characteristic (ROC) curve analysis showed the superiority of BNP (ROC areas 0.942 for definite LVSD, P<0.03; 0.934 for borderline LVSD, P<0.003) compared to N-BNP or N-ANP. Peptide levels, major ECG abnormality and ischaemic heart disease (IHD) history were independent predictors of LVSD. Logistic regression modelling incorporating these factors improved ROC areas for all natriuretic peptides. The specificity of all natriuretic peptides is enhanced by consideration of these factors. CONCLUSIONS: In population screening for definite LVSD, consideration of plasma natriuretic peptide levels together with the presence of major ECG abnormalities and IHD history reduces by a factor of six (in comparison to consideration of plasma natriuretic peptide levels in isolation) the number of subjects requiring echocardiography to detect one case of LVSD (for BNP, 44 falling to seven). Similar improvements were evident for N-ANP and N-BNP. Inclusion of major ECG abnormalities and IHD history improves the performance of any natriuretic peptide used in screening programmes for ruling in undiagnosed LVSD.

Aged↗

Noninvasive prediction of coronary artery disease progression by comparison of serial exercise electrocardiography and dipyridamole stress echocardiography.

BACKGROUND: The possibility of noninvasive prediction of angiographically assessed coronary artery disease (CAD) progression by comparison of serial studies of exercise electrocardiography (EET) and dipyridamole stress echocardiography (DET) is not known. AIM: To assess the relative value of EET and DET in predicting angiographically assessed progression of CAD. METHODS: From the Institute of Clinical Physiology, National Research Council, Pisa Italy stress echo data bank (1983-1998), we selected 46 patients with two repeated EET, DET and coronary angiography (CA) in two different hospital admissions (46+/-30 months). A priori, angiographic progressors were defined as any stenosis progression to occlusion and/or any stenosis >30% with >20% stenosis progression measured by visual and quantitative CA. EET progressors were defined as a previous negative test becoming positive or as a positive test with decrease in ischemic threshold response in the second test. DET progressors were defined as previous negative test becoming positive or as a positive test with a more severe ischemic response in the second test. RESULTS: Angiographic progressors were 31/46 patients (67%) and angiographic nonprogressors were 15/46 (33%). When angiography was taken as the gold standard, there were no differences in sensitivity for EET and DET (87 vs. 87%). Specificity was significantly higher for DET (93 vs. 40% p =< 0.001). By kappa statistics DET had a good concordance (kappa = 0.768) and EET a poor concordance (kappa = 0.299) with angiographic progression. CONCLUSION: DET is more accurate than EET at predicting angiographically assessed CAD progression.

Coronary Angiography↗

Willem Einthoven and the birth of clinical electrocardiography a hundred years ago.

The first electrocardiogram (ECG) from the intact human heart was recorded with a mercury capillary electrometer by Augustus Waller in May 1887 at St. Mary's Hospital, London. The tracings were poor and exhibited only 2 distorted deflections. Willem Einthoven (1860-1927) who was professor of physiology at the University of Leiden, The Netherlands, began his studies of the ECG with the mercury capillary electrometer, and improved its distortion mathematically so that he was finally able to register a good representation of the ECG before the beginning of the twentieth century. He later further improved ECG recordings with the introduction of a string galvanometer of his design. Einthoven published his first article about the string galvanometer in 1901, followed by a more detailed description in 1903 which included a report of ECGs taken with the new instrument. The year 2002 marks the centennial of Willem Einthoven's first recording of the ECG in a clinically applicable fashion with the string galvanometer. The clinical use of Einthoven's immobile equipment required transtelephonic transmission of the ECG from the physiology laboratory to the clinic at the Academic Hospital about a mile away as documented in the 1906 paper on the "télécardiogramme". This report contained a wealth of ECG patterns and arrhythmias. Einthoven developed a system of electrocardiographic standardization that continues to be used all over the world and introduced the triaxial bipolar system with 3 limb leads and thus established uniformity of the recording process. Einthoven also conceived the famous equilateral triangle with leads I, II, and III at its sides and the calculation of the electrical axis (in the frontal plane) depicted as a single vector with an arrow at the center of the triangle. Einthoven recognized the great potential importance of the ECG as a diagnostic and investigative tool and his achievements made him the founder of modern electrocardiography. He was awarded the Nobel Prize in 1924 (2 years after Waller's death) in physiology and medicine, "for the discovery of the mechanism of the electrocardiogram."

Electrocardiography↗

Biplane transoesophageal echocardiographic detection of myocardial ischaemia in patients with coronary artery disease undergoing non-cardiac surgery: segmental wall motion vs. electrocardiography and haemodynamic performance.

Intra-operative segmental wall motion abnormalities (SWMA) detected by transoesophageal echocardiography (TOE) have been shown to be a sensitive indicator of myocardial ischaemia. To determine the incidence and characteristics of segmental wall motion abnormalities and to relate these changes to perioperative myocardial ischaemia, biplane TEE, electrocardiogram (ECG) (II+V5) and pulmonary capillary wedge pressure (PCWP) were continuously monitored in 62 consecutive patients with ischaemic heart disease undergoing non-cardiac surgery. Short-axis view at mid-papillary level in transverse scan (T-scan) and long-axis in longitudinal (L-scan) two-chamber view were used for wall motion analysis. New segmental wall motion abnormalities were detected in 16 of 64 patients (25%) using biplane transoesophageal echocardiography. Monoplane transoesophageal echocardiography showed a sensitivity of 75% and a specificity of 100%, electrocardiogram two lead showed a sensitivity of 56% and a specificity of 98%, whereas pulmonary capillary wedge pressure had a sensitivity of 25%, and a specificity of 93% and pressure rate quotient (PRQ) < 1 demonstrated sensitivity of 19% and a specificity of 92% in the detection of myocardial ischaemia. It is concluded that the long-axis view of the left ventricle provides additional information for the detection of segmental wall motion abnormalities. Neither changes in haemodynamic performance nor in electrocardiography leads II and V5 match those of transoesophageal echocardiography for the identification of myocardial ischaemia.

Adult↗

Central venous catheter placement in children: evaluation of electrocardiography using J-wire.

Misplacement of a central venous catheter may lead to myocardial perforation and dysrhythmia. Atrial electrocardiography (ECG) through a saline column is an effective but complex method to determine the accurate location of catheters. We evaluated a simplified variant of this technique using the guidewire as an internal electrode in 23 children (5-16 years old) undergoing spinal surgery. Catheters were placed using a Seldinger technique after jugular or subclavian venous puncture. Each time the operator recognized the atrial signal, the catheter was found to be correctly placed on the chest radiograph (20/23). In three patients, the atrial signal was not obtained. A technical error was responsible in one case whereas the two others were related to aberrant migrations of the catheter either into a subclavian vein or into the pleura. In this latter case, the complication was unrecognized on the first radiograph despite malposition having been predicted by atrial ECG. We conclude that a method using atrial ECG guidance is sensitive and specific, and may be an alternative to the classical chest radiograph to detect accurate placement of central venous catheters in children.

Catheterization, Central Venous↗

P wave signal-averaged electrocardiography to identify risk for atrial fibrillation.

AF is the most common sustained cardiac arrhythmia, and this prevalence is increasing. The impact of AF on morbidity and mortality is substantial, as are the socioeconomic consequences like higher health care costs, chronic disease management, and disabilities. Early recognition of patients at high risk for AF, combined with effective management, may help prevent AF from becoming chronic, helping to minimize potential health risks, costs, and other complications. P wave signal-averaged electrocardiography (SAECG) has been shown to have a potential role in identifying patients at risk of developing paroxysmal AF and those likely to change from paroxysmal AF to chronic AF. The theoretical rationale of P wave SAECG in patients with AF is delay in the intraatrial and interatrial conduction. Intraatrial conduction delays can be seen on the surface electrocardiogram as P wave prolongation, which is more visible with averaging techniques and high resolution recording devices. Averaging followed by amplification after proper filtering of the electrical signal allows more precise measurements of duration and amplitude of the P wave. Data on reproducibility, filter settings, number of beats to be averaged, and definitions of the onset and offset depend on the system used, which can be QRS or, preferably, P wave triggered. A prolonged P wave duration is one of the best predictors of perioperative AF, but the role of P wave SAECG in the paroxysmal form is less well defined. Combining P wave duration with other predictors for AF improves the diagnostic value of P wave SAECG.

Atrial Fibrillation↗

Filtered QRS duration on signal-averaged electrocardiography predicts inducibility of ventricular tachycardia in arrhythmogenic right ventricle dysplasia.

Treatment of arrhythmogenic right ventricular dysplasia (ARVD) is mostly based on the prevention of sudden cardiac death that results from arrhythmias. A clinical history suggestive of ARVD requires careful evaluation including electrophysiological study. The potential ability to identify those patients who will have inducible VT with electrophysiological study will enable better risk stratification and selection of vulnerable patients for electrophysiologically guided therapy. The purpose of the study was to evaluate the predictive ability of signal-averaged electrocardiography (SAECG) to predict inducibility of VT in patients with ARVD. The patient population consisted of 31 ARVD patients diagnosed with McKenna's criteria who underwent electrophysiological study. Electrophysiological study was considered positive if sustained monomorphic VT was induced. The sensitivity, specificity, and predictive accuracy of various SAECG criteria for inducibility of sustained monomorphic VT were also calculated. Twenty-one patients had inducible VT. The filtered QRS duration (fQRS), duration of signal <40 uV (LAS40), and root mean square voltage in the last 40 ms of QRS duration (RMS40) in ARVD patients induced versus noninduced were 122 +/- 21 and 103 +/- 8 ms (P=0.007), 45 +/- 20 and 28 +/- 14 ms (P=0.02), 19 +/- 19 and 32 +/- 22 uV (0.03), respectively. The ejection fractions were comparable in both groups. fQRS duration > or =110 ms had sensitivity of 91%, specificity of 90%, and a total predictive accuracy of 90% in predicting inducibility of VT in these patients. Filtered QRS duration on SAECG is predictive of electrophysiological study outcome in ARVD. Further studies will be needed to determine if SAECG results can predict the development of ventricular arrhythmias during follow-up.

Adult↗

P wave signal-averaged electrocardiography predicts recurrence of paroxysmal atrial fibrillation in patients with Wolff-Parkinson-White syndrome who underwent successful catheter ablation: a prospective study.

INTRODUCTION: Paroxysmal atrial fibrillation (PAF) frequently occurs in patients with Wolff-Parkinson-White (WPW) syndrome. Catheter ablation of the accessory pathway eliminates PAF in some patients, but PAF frequently recurs in other patients. The present study was designed to determine prospectively whether P wave signal-averaged electrocardiography (P-SAECG) predicts the recurrence of PAF after successful ablation in patients with WPW syndrome. METHODS AND RESULTS: Forty-six patients with WPW syndrome who had episodes of PAF were prospectively followed. SAECG recording was performed on day 7 after successful ablation of the accessory pathway at study entry. Abnormal P-SAECG for the prediction of recurrence of PAF was defined as a filtered P wave duration > 130 msec. Eleven patients had an abnormal P-SAECG (group 1), whereas 35 patients (group 2) did not. The two groups did not differ in terms of gender, age, left atrial dimension, and atrial vulnerability as determined by electrophysiologic study. During follow-up (40 +/- 19 months), the recurrence of PAF was noted in 10 (91%) of 11 patients in group 1, whereas it was observed in only 2 (6%) of 35 patients in group 2. Kaplan-Meier analysis revealed that the recurrence of PAF was significantly more frequent in group 1 than in group 2 (log rank test, P < 0.0001). By multivariate analysis, filtered P wave duration >130 msec was an independent predictor of recurrence of PAF after ablation (Chi-square = 21.5, P < 0.0001). CONCLUSION: The results of this study indicate that P-SAECG may be useful for identifying patients at risk for recurrence of PAF after successful ablation of WPW syndrome.

Adolescent↗

Mechanisms of abnormal Q waves in hypertrophic cardiomyopathy assessed by intracoronary electrocardiography.

INTRODUCTION: To clarify the mechanisms of abnormal Q waves in hypertrophic cardiomyopathy (HCM), local epicardial electrical activities were assessed by intracoronary electrocardiography (ECG). METHODS AND RESULTS: Unipolar intracoronary ECG was recorded by introducing a guide wire for angioplasty into the left anterior descending artery (LAD) in 20 patients with HCM and 10 control subjects. Intracoronary ECG showed no Q waves in any control subjects. Intracoronary ECG showed no Q waves in 8 HCM patients without abnormal Q waves on surface ECG. In 12 HCM patients with abnormal Q waves on surface ECG, 4 showed Q waves on intracoronary ECG associated with regional wall-motion abnormalities, suggesting Q waves are formed by loss of electrical forces due to transmural myocardial fibrosis. The remaining 8 patients, who did not have Q waves on intracoronary ECG, showed greater thickening of the basal free wall than the apical free wall, with no wall-motion abnormalities. Intracoronary ECG was characterized by increased R or R' waves and prolonged R peak times at the proximal LAD, suggesting Q waves are formed by increased electrical forces of hypertrophied basal septal and/or ventricular free wall, unopposed by apical forces. CONCLUSION: The study findings provide evidence for two mechanisms of abnormal Q waves in HCM: (1) loss of electrical forces due to transmural myocardial fibrosis, and (2) altered direction of resultant initial QRS vector due to increased electrical forces of disproportionate hypertrophy of the basal septal and/or ventricular free wall, unopposed by apical forces.

Adult↗

Diagnostic value of electrocardiography and echocardiography for familial hypertrophic cardiomyopathy in genotyped children.

AIM: The aim of the study was to evaluate electrocardiography and echocardiography in the diagnosis of familial hypertrophic cardiomyopathy in children, using the genetic status as the criterion of reference. METHODS AND RESULTS: We analysed 35 children (<18 years) from 13 families with identified mutations: 16 were genetically affected (11.2 +/- 3 years), 19 unaffected (13.1 +/- 2.8 years). Conventional major diagnostic criteria were: left ventricular wall thickness >95% confidence interval on the echocardiogram; abnormal Q waves, left ventricular hypertrophy (voltage >95th percentile), or marked ST-T changes on the electrocardiogram. Twenty-two minor electrocardiographic and echocardiographic criteria were also analysed. Using major criteria, the specificity of the electrocardiogram and echocardiogram was excellent (100% for both) but sensitivity was particularly low (38% and 50% respectively). However, when four relevant additional criteria (QRS axis, left atrium dimension, intraventricular septum/posterior wall ratio, E/A wave ratio) were taken into account, sensitivity increased to 88% and specificity remained high (95%). CONCLUSIONS: (1) Familial hypertrophic cardiomyopathy was diagnosed in only approximately 50% of genetically affected children by conventional electrocardiographic and/or echocardiographic criteria. (2) Relevant additional diagnostic criteria were selected so that nearly all children considered as healthy carriers of a mutation (based on conventional criteria) could be identified with excellent specificity.

Adolescent↗

Angiographical and Doppler flow-derived parameters for assessment of coronary lesion severity and its relation to the result of exercise electrocardiography. DEBATE study group. Doppler Endpoints Balloon Angioplasty Trial Europe.

AIMS: Evaluation of angiographical and intracoronary Doppler-derived parameters of coronary stenosis severity. METHODS AND RESULTS: A total of 225 patients with one-vessel disease were studied before PTCA and at 6 months follow-up. Exercise electrocardiography was performed to document presence (n = 157) or absence (n = 138) of an ST segment shift (> or =0.1 mV). Intracoronary blood flow velocity analysis was performed to determine the proximal/distal flow velocity ratio, the distal diastolic/systolic flow velocity ratio and coronary flow velocity reserve. Receiver operator characteristic curves were calculated to assess the predictive value of these variables compared with the exercise test. The distal coronary flow velocity reserve demonstrated the best linear correlation for both percentage diameter stenosis and minimum lumen diameter (r = 0.67 and r = 0.66; P<0.01), compared to the diastolic/systolic flow velocity ratio (r = 0.19 and r = 0.14; P<0.01) and the proximal/distal flow velocity ratio (r = 0.03 and r = 0.07; not significant). The areas under the curve were 0. 84+/-0.02; 0.82+/-0.03 and 0.83+/-0.03 for diameter stenosis, minimum lumen diameter and coronary flow velocity reserve, respectively. Logistic regression analysis revealed that the percentage diameter stenosis or minimum lumen diameter and coronary flow velocity reserve were independent predictors for the result of stress testing. CONCLUSIONS: The distal coronary flow velocity reserve is the best intracoronary Doppler parameter for evaluation of coronary narrowings. Angiographical estimates of coronary lesion severity and distal coronary flow velocity reserve are good and independent predictors for the assessment of functional severity of coronary stenosis, emphasizing the complementary role of these parameters for clinical decision making.

Adult↗

Transesophageal electrocardiography and atrial pacing in children.

The technique and spectrum of clinical application of transesophageal electrocardiography and atrial pacing in children is demonstrated in this article. Special emphasis is laid on the usefulness of the method in newborns and infants for the management of supraventricular tachycardia.

Adolescent↗