The relationship between programmed pacemaker pulse amplitude and the surface electrocardiogram recorded amplitude: application of a new high-bandwidth electrocardiogram system

Background

Recording and displaying outputs from electronic pacemakers with electrocardiogram (ECG) recorders typically used in clinical practice have presented a number of technical limitations. We have recently reported on a new high-bandwidth ECG system and have shown that it is capable of reproducing accurate pulse amplitudes and durations from the body surface. In the present work, we have used our data to calculate a transform function between the programmed pacemaker output voltage and the amplitude on the body surface.

Methods

We recorded 3 high-bandwidth (75,000 samples per second) ECGs from each of 100 pacemaker patients at 3 different programmed outputs. Each pacemaker pulse was isolated using the criterion standard annotations, and the pulses were transformed from the 8 independent leads to an XYZ vector using the Dower transform. The magnitude of the vector was calculated. Linear regression techniques were used to learn a transfer function over the records of the first 50 patients. These results were tested against the second 50 patients.

Results

The measured pacemaker pulse vector magnitude has a linear relationship to the programmed pacemaker amplitude on a per-patient basis for most of the patients in the training database. The linear transform models were tested against the testing set with an R² metric of 0.38 for the atrial pulses and 0.54 for the right ventricular pulses.

Conclusion

Understanding the relationship between the generated pacemaker pulses and the measurements at the body surface will help drive specifications for pacemaker pulse detection among the various device manufactures.     

Changes in the amplitude of electrocardiogram QRS complexes during follow-up of heart failure patients

Introduction

Changes in the electrocardiogram QRS amplitudes (ECGΔ) during follow-up of heart failure (HF) patients have not been clinically exploited heretofore.

Methods

We examined ECGΔ during follow-up of HF patients by employing 42 triplets of ECGs, other laboratory and HF-related clinical data corresponding to clinical stability, worsening, and recovery from 37 HF patients.

Results

The % changes (Δ%) in the summed QRS amplitude of all 12 leads (ΣQRS_12L), 6 precordial leads (ΣQRS_V1-V6), 6 limb leads (ΣQRS_6L), leads I+II (ΣQRS_{I + II}), and lead aVR were evaluated. Also relationships between the ECG variables and body weight (BW), percent body-fat, and B-type natriuretic peptide (BNP) were examined. The QRS amplitude(s) in all ECG variables decreased from clinical stability to worsening HF, and returned to baseline at recovery. During HF worsening, Δ% was highest in lead aVR (−15.3 ± 12.3%), followed by Δ% in ΣQRS_6L (−12.9 ± 10.1%) and ΣQRS_{I + II} (−12.1 ± 10.8%). At worsening HF and its recovery, Δ% in ΣQRS_6L correlated with Δ% in percent body-fat (r = 0.333, P = .031; r = 0.308, P = .047). At recovery, Δ% in each ECG variable correlated with Δ% in BW. Receiver operating characteristic (ROC) analysis showed that ≥16% reduction of ΣQRS_6L and ΣQRS_{I + II} discriminated between stable and worsening HF, with a sensitivity of 43% and 40%, and specificity of 98% for both. ECG variables from limb lead(s) had as good area under the curve (AUC) (0.78-0.84) as BNP (AUC: 0.88) for identifying worsening HF.

Conclusions

Changes of the QRS amplitudes in ECGs are as useful for monitoring HF patients as BNP.     

Nomenclature and description of the electrocardiogram

In view of the present confusion regarding the terms to be applied to the peaks of the electrocardiogram, the usage of Einthoven and of Lewis has been reviewed in the hope of finding a reasonable solution. Lewis' modification of Einthoven's terminology is recommended.Suggestions are made for naming the peaks of certain types of QRS not particularly mentioned by Lewis, namely, the M complex, the vibratory QRS, and the solely downward deflection.A method of describing notching and slurring of QRS is outlined, and certain features of the measurement of the duration of P, QRS, and Q-T are emphasized.A definition of the term diphasic is suggested, to be applied to the P and T waves; also, a method of describing these waves which is considered adequate for statistical grouping is presented.     

Brugada phenocopy: A new electrocardiogram phenomenon

Brugada phenocopies(BrP) are clinical entities that are etiologically distinct from true congenital Brugada syndrome. BrP are characterized by type 1 or type 2 Brugada electrocardiogram(ECG) patterns in precordial leads V1-V3. However, BrP are elicited by various un-derlying clinical conditions such as myocardial ischemia, pulmonary embolism, electrolyte abnormalities, or poor ECG filters. Upon resolution of the inciting underlying pathological condition, the BrP ECG subsequently nor-malizes. To date, reports have documented BrP in the context of singular clinical events. More recently, recur-rent BrP has been demonstrated in the context of re-current hypokalemia. This demonstrates clinical repro-ducibility, thereby advancing the concept of this new ECG phenomenon. The key to further understanding the pathophysiological mechanisms behind BrP requires experimental model validation in which these phenom-ena are reproduced under strictly controlled environ-mental conditions. The development of these validation models will help us determine whether BrP are tran-sient alterations of sodium channels that are not repro-ducible with a sodium channel provocative test or al-ternatively, a malfunction of other ion channels. In this editorial, we discuss the conceptual emergence of BrP as a new ECG phenomenon, review the progress made to date and identify opportunities for further investiga-tion. In addition, we also encourage investigators that are currently reporting on these cases to use the term BrP in order to facilitate literature searches and to help establish this emerging concept.     

A new chapter of electrocardiography: The progressive variations in the amplitude of the electrocardiogram

Translation fromActualités Cardiologues et Angéiolgiques Internationales 1966;4:241–258.     

Late complications of Candida (Torulopsis) glabrata fungemia: description of a phenomenon

Complications occurring > 1 month after Candida glabrata fungemia have not been studied. We conducted a study to determine the frequency and morbidity of complications of C. glabrata bloodstream infections occurring > 1 month after infection. Late complications were common (incidence 9.9 per 100 patient years), and most often occurred within the first year. In a multivariate analysis, late complications were associated with the presence of diabetes mellitus [odds ratio (OR) 12.2; 95% confidence interval (CI) 1.2-130] and chronic renal failure (OR 14.7; 95% CI 1.2-184). These data suggest that careful long-term follow-up of patients with C. glabrata fungemia is important and present an opportunity to explore secondary prophylaxis.     

Transfusion associated microchimerism: a heretofore little recognized complication following transfusion

Potent antiplatelet and antithrombotic agents have significantly reduced mortality in the setting of acute coronary syndromes and percutaneous coronary intervention. However these agents are associated with increased bleeding which is in turn associated with adverse clinical outcomes. In many centers, transfusion is often used to correct for blood loss. Blood transfusion in the setting of acute coronary syndrome has been associated with adverse clinical outcomes including increased mortality. Transfusion associated microchimerism (TA-MC) is a newly recognized complication of blood transfusion. There is engraftment of the donor’s hematopoietic stem cells in patients who then develop microchimerism. This article discusses the association of bleeding/blood transfusion with adverse outcomes and the potential role of TA-MC in clinical outcomes. The authors have received research grant support and consulting fees in the past from Eli Lilly, Schering Plough, and Astra Zeneca. Dr. Vijayalakshmi Kunadian has received unrestricted educational research grant support from South Cleveland Heart Fund, The James Cook University Hospital, Middlesbrough, United Kingdom.     

An accordion phenomenon with ST-segment elevation of electrocardiogram and anginal chest pain: a case report

Tortuous coronary arteries frequently make percutaneous coronary intervention (PCI) difficult by causing less accessibility of guidewire toward the target lesion. After guidewire has been passed through the target lesion, it often assists a balloon catheter and stent system insertion along the stiff guidewire. However, artificial kinking and wrinkling might induce pseudo-narrowing of coronary arteries, which has been recognized as an "accordion phenomenon." We describe an educational case of an accordion phenomenon with ST-segment elevation of electrocardiogram and anginal chest pain when the stiff guidewire which had been withdrawn was advanced again into the distal site after deploying stents.     

体位对心电图的影响

目的观察不同体位下心电图各波段振幅的改变,并分析体位对其影响。方法50例受检者均接受12导联动态心电图(Holter)及12导联电话传输远程心电图(TTM)记录,分别比较TTM和Holter在5种不同体位下的心电图各波段振幅。结果在II导联,体位对TTM和Holter各波段振幅造成的影响均无统计学意义;TTM的V1导联T波右侧卧位振幅较平卧位大(p=0.047),V5导联P波立位较平卧位高(p=0.044);Holter的V1导联S波左侧卧位较平卧位低(p=0.045),V5导联R波左侧卧位较平卧位高(p=0.04)。结论体位改变对TTM和Holter所测各波段振幅在肢体导联没有影响,胸导联振幅受体位影响而变化。     

Diagnostic value of amplitude variations of the Q wave during computerized stress electrocardiogram

Variations in the amplitude of the Q wave in lead CM5 during computerised exercise stress testing were studied in 220 patients and compared with the results of coronary angiography. The average amplitude of the Q wave increases during exercise in athletes (n = 30) from 3 +/- 2.75 mm to 4.72 +/- 2.35 mm (p less than 0.01), and in subjects without coronary artery disease (n = 49) from 0.92 +/- 1.05 mm to 1.75 +/- 1.62 mm (p less than 0.01). The Q wave did not vary significantly during exercise in patients with coronary disease but without previous infarction (n = 88) (0.70 +/- 0.91 mm to 0.62 +/- 0.85 mm). The amplitude of the Q wave did tend to decrease in patients with previous myocardial infarction (n = 83) from 1.96 +/- 2.05 mm to 1.35 +/- 1.26 mm (p less than 0.05). It is therefore possible to define a new diagnostic criterion of coronary disease: "the exercise stress test is said to be positive (delta q+) when the Q wave tends to decrease or remains stable during exercise, and negative (delta q-) when the Q wave amplitude increases during exercise". This criterion was tested in 49 normal and 83 coronary patients without infarction. The sensitivity (Se) was 79 p. 100 and the specificity (Sp) 65 p. 100, so correctly classifying 74 p. 100 of patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dissecting aneurysm of the aorta,correctly diagnosed : With description of a sign heretofore not mentioned

A case with dissecting aneurysm of the thoracic aorta is reported in which the correct diagnosis was established.     

Short duration exercise increases breath hydrogen excretion after lactulose ingestion: description of a new phenomenon

OBJECTIVE: There is limited information on the effect of exercise on colonic function. Beneficial effects have been described, including prevention of colon cancer. In the present study, we demonstrate that short duration exercise results in enhancement of breath hydrogen excretion after consumption of lactulose. METHODS: Twelve normal volunteers who performed regular exercise were recruited. Each study subject underwent four study sessions (two resting and two exercise) after consumption of 10 g of crystalline lactulose. Colonic hydrogen production was measured in mid-expiratory breath samples obtained at baseline and frequent intervals to 420 min. Exercise sessions consisted of 5 min on a treadmill at a 20% incline at 10 km/h. This was performed 180 min after lactulose ingestion in the two exercise sessions. RESULTS: A characteristic pattern in the hydrogen concentration versus time curves was seen after exercises, consisting of an initial decrease then an increase in concentration above baseline for up to 3 h. Mean area under the curve from 0 to 420 min for resting studies was 5,156 +/- 2,621 ppm/min and was 7,051 +/- 2,447 ppm/min for exercise studies, p < 0.05 (37% increase). Mean area under the curve from 180 to 420 min was 2,808 +/- 1,592 ppm/min for resting studies and 4,543 +/- 1,729 for exercise studies, p < 0.005 (62% increase). CONCLUSION: This study demonstrates that exercise potentially enhances the metabolism of lactulose by colonic bacteria. The authors postulate that this effect is due to stirring of the colonic contents. The described phenomenon may explain, in part, the beneficial effects of exercise on colonic mucosa.     

动态心电图J波现象分布特征的调查

目的通过同步12导联动态心电图(Dynamic electrocardiogram,DECG)观察不同人群和不同方法的J波阳性率及分布特征。方法观察DECG不同性别组和不同导联的J波阳性率以及常规心电图(electrocardiogram,ECG)的J波阳性率。J波阳性率组间比较选择χ~2检验。结果女性组J波阳性率58.3%(n=307);男性组J波阳性率88.2%(n=247),显著高于女性组(χ~2=4.28E2,p=0.000)。ECG组J波阳性率48.0%(n=100);DECG组J波阳性率71.7%(n=554),显著高于ECG组(χ~2=2.18E1,p=0.000)。J波阳性DECG中V2导联J波阳性率81%(n=100),在12个导联中阳性率最高。结论 J波在DECG中属常见心电现象;男性组J波阳性率显著高于女性组;J波的空间分布以前间壁最常见;DECG组J波阳性率显著高于ECG组。     

Comparison of the amplitude of the P-wave from intracardiac electrocardiogram obtained by means of a central venous catheter filled with saline solution to that obtained via esophageal electrocardiogram

Recognition of the P wave is important for the correct characterization of atrial and ventricular arrhythmias. When the P wave is difficult to identify on standard electrocardiography (SECG), either esophageal electrocardiography (EECG) or intracardiac electrocardiography (IC-ECG), central venous catheter may be used. The feasibility of these methods has already been demonstrated, but there is no published study comparing them. This study compared the amplitude of the P wave obtained by IC-ECG with those of the P waves obtained by EECG and SECG. SECG, EECG, and IC-ECG were performed on each patient. IC-ECG and EECG made it possible to register P waves larger than registered by SECG (p <0.00001). The difference between the largest P waves obtained with IC-ECG (5.93 +/- 3.56 mm) and EECG (4.67 +/- 2.16 mm) was not statistically significant (p = 0.1953). In conclusion, IC-ECG is easy to perform and magnifies the P wave at least as effectively as EECG.