QTc interval in patients with changing edematous states: implications on interpreting repeat QTc interval measurements in patients with anasarca of varying etiology and those undergoing hemodialysis

Role of deep learning methods in screening for subcutaneous implantable cardioverter defibrillator in heart failure

INTRODUCTION

S-ICD eligibility is assessed at pre-implant screening where surface ECG traces are used as surrogates for S-ICD vectors. In heart failure (HF) patients undergoing diuresis, electrolytes and fluid shifts can cause changes in R and T waves. Subsequently, T:R ratio, a major predictor of S-ICD eligibility, can be dynamic.

METHODS

This is a prospective study of patients with structurally normal hearts and HF patients undergoing diuresis. All patients were fitted with Holters® to record their S-ICD vectors. Our deep learning model was used to analyze the T:R ratios across the recordings. Welch two sample t-test and Mann-Whitney U were used to compare the data between the two groups.

RESULTS

Twenty-one patients (age 58.43 ± 18.92, 62% male, 14 HF, 7 normal hearts) were enrolled. There was a significant difference in the T:R ratios between both groups. Mean T: R was higher in the HF group (0.18 ± 0.08 vs 0.10 ± 0.05, p < .001). Standard deviation of T: R was also higher in the HF group (0.09 ± 0.05 vs 0.07 ± 0.04, p = .024). There was no difference between leads within the same group.

CONCLUSIONS

T:R ratio, a main determinant for S-ICD eligibility, is higher and has more tendency to fluctuate in HF patients undergoing diuresis. We hypothesize that our novel neural network model could be used to select HF patients eligible for S-ICD by better characterization of T:R ratio reducing the risk of T-wave over-sensing (TWO) and inappropriate shocks. Further work is required to consolidate our findings before applying to clinical practice.

Deep learning methods for screening patients' S-ICD implantation eligibility

Subcutaneous Implantable Cardioverter-Defibrillators (S-ICDs) are used for prevention of sudden cardiac death triggered by ventricular arrhythmias. T Wave Over Sensing (TWOS) is an inherent risk with S-ICDs which can lead to inappropriate shocks. A major predictor of TWOS is a high T:R ratio (the ratio between the amplitudes of the T and R waves). Currently, patients' Electrocardiograms (ECGs) are screened over 10 s to measure the T:R ratio to determine the patients' eligibility for S-ICD implantation. Due to temporal variations in the T:R ratio, 10 s is not a long enough window to reliably determine the normal values of a patient's T:R ratio. In this paper, we develop a convolutional neural network (CNN) based model utilising phase space reconstruction matrices to predict T:R ratios from 10-second ECG segments without explicitly locating the R or T waves, thus avoiding the issue of TWOS. This tool can be used to automatically screen patients over a much longer period and provide an in-depth description of the behavior of the T:R ratio over that period. The tool can also enable much more reliable and descriptive screenings to better assess patients' eligibility for S-ICD implantation.

Automated diagnosis of congestive heart failure using dual tree complex wavelet transform and statistical features extracted from 2s of ECG signals

Identification of alarming features in the electrocardiogram (ECG) signal is extremely significant for the prediction of congestive heart failure (CHF). ECG signal analysis carried out using computer-aided techniques can speed up the diagnosis process and aid in the proper management of CHF patients. Therefore, in this work, dual tree complex wavelets transform (DTCWT)-based methodology is proposed for an automated identification of ECG signals exhibiting CHF from normal. In the experiment, we have performed a DTCWT on ECG segments of 2s duration up to six levels to obtain the coefficients. From these DTCWT coefficients, statistical features are extracted and ranked using Bhattacharyya, entropy, minimum redundancy maximum relevance (mRMR), receiver-operating characteristics (ROC), Wilcoxon, t-test and reliefF methods. Ranked features are subjected to k-nearest neighbor (KNN) and decision tree (DT) classifiers for automated differentiation of CHF and normal ECG signals. We have achieved 99.86% accuracy, 99.78% sensitivity and 99.94% specificity in the identification of CHF affected ECG signals using 45 features. The proposed method is able to detect CHF patients accurately using only 2s of ECG signal length and hence providing sufficient time for the clinicians to further investigate on the severity of CHF and treatments.

The Effect of Diuresis on the Paced QRS Complexes in Pacing-Dependent Patients with Heart Failure

BACKGROUND

Augmentation of the amplitude of QRS complexes with diuretic therapy for patients with congestive heart failure has been well documented. However, the effect of diuresis on the paced QRS complexes in pacing-dependent patients with heart failure is scarce.

OBJECTIVE

To investigate the effect of diuresis on the paced QRS complexes in pacing-dependent patients with heart failure.

METHOD

Thrity-two consecutive pacing-dependent patients with heart failure were enrolled in this study. Before and after diuresis, the sums of paced QRS amplitude of leads I+II (ΣpQRSI+II ), six limb leads (ΣpQRS6L ), leads V1 -V3 (ΣpQRSV1-V3 ), leads V4 -V6 (ΣpQRSV4-V6 ), leads V1 -V6 (ΣpQRSV1-V6 ), and lead aVR (pQRSaVR ), paced QRS duration (pQRSd ), paced QT intervals (pQT) and the body weight of each patient were measured, then the % changes (Δ%) in paced electrocardiogram (ECG) variables and the Δ% in body weight were evaluated.

RESULTS

Compared with before diuresis, paced ECG variables significantly increased and body weight significantly decreased after diuresis, Δ% in paced QRS amplitude(s) in all ECG variables (ΣpQRSI+II, ΣpQRS6L, ΣpQRSV1-V3 , ΣpQRSV4-V6 , ΣpQRSV1-V6 , and pQRSaVR ) correlated well with Δ% in body weight (r = 0.416, r = 0.849, r = 0.901, r = 0.371, r = 0.837, r = 0.619, and P = 0.018, P < 0.001, P < 0.001, P = 0.037, P < 0.001, P < 0.001), while there was no correlation between Δ% in pQRSd and pQT and Δ% in body weight.

CONCLUSIONS

The changes in amplitude of paced QRS complexes may be useful for the monitoring of therapy of pacing-dependent patients with heart failure.

Rationale and design for the Predictors of Arrhythmic and Cardiovascular Risk in End Stage Renal Disease (PACE) study

BACKGROUND

Sudden cardiac death occurs commonly in the end-stage renal disease population receiving dialysis, with 25% dying of sudden cardiac death over 5 years. Despite this high risk, surprisingly few prospective studies have studied clinical- and dialysis-related risk factors for sudden cardiac death and arrhythmic precursors of sudden cardiac death in end-stage renal disease.

METHODS/DESIGN

We present a brief summary of the risk factors for arrhythmias and sudden cardiac death in persons with end-stage renal disease as the rationale for the Predictors of Arrhythmic and Cardiovascular Risk in End Stage Renal Disease (PACE) study, a prospective cohort study of patients recently initiated on chronic hemodialysis, with the overall goal to understand arrhythmic and sudden cardiac death risk. Participants were screened for eligibility and excluded if they already had a pacemaker or an automatic implantable cardioverter defibrillator. We describe the study aims, design, and data collection of 574 incident hemodialysis participants from the Baltimore region in Maryland, U.S.A.. Participants were recruited from 27 hemodialysis units and underwent detailed clinical, dialysis and cardiovascular evaluation at baseline and follow-up. Cardiovascular phenotyping was conducted on nondialysis days with signal averaged electrocardiogram, echocardiogram, pulse wave velocity, ankle, brachial index, and cardiac computed tomography and angiography conducted at baseline. Participants were followed annually with study visits including electrocardiogram, pulse wave velocity, and ankle brachial index up to 4 years. A biorepository of serum, plasma, DNA, RNA, and nails were collected to study genetic and serologic factors associated with disease.

DISCUSSION

Studies of modifiable risk factors for sudden cardiac death will help set the stage for clinical trials to test therapies to prevent sudden cardiac death in this high-risk population.

Electrocardiogram voltage attenuation and shortening of the duration of P-waves, QRS complexes, and QT intervals

Multiple pathologies in concert may lead to attenuation of the electrocardiogram (ECG) voltage. A case of a patient illustrating the above is presented, who showed marked attenuation of the ECG voltage. Automated values of the amplitude of the ECG QRS complexes, P-waves, and T-waves (in mm), duration of the QRS complexes, P-waves, and QT intervals (in ms), in 2 ECGs were compared. The patient was a 64-year-old woman who developed in the setting of a fatal illness, pleural and pericardial effusions, pneumomediastinum, pneumoperitoneum, subcutaneous emphysema in the neck and chest, peripheral edema with weight gain of 43.4 lbs, marked hypoalbuminemia, abnormal liver tests, and renal failure. All the above pathologies led to a marked attenuation of the ECG voltage, and shortening of the mean P-wave, QRS complexes, and QTc interval durations. The postulated mechanism of the observed ECG phenomena is discussed.

Changes in the QT intervals, QT dispersion, and amplitude of T waves after hemodialysis

BACKGROUND

Increased QT dispersion (QTd) has been associated with an increased risk for ventricular arrhythmias and sudden death in the general population and in various clinical states.

METHODS

We investigated the impact of hemodialysis (HD) on QT, QTd, and T-wave amplitude in subjects with end-stage renal failure. Data on 49 patients on chronic HD were studied. The QT, QTd, and the sum of amplitude of T waves (SigmaT) in millimetre in the 12 ECG leads, along with a host of other ECG parameters, body weight, blood pressure, heart rate, electrolytes, and hemoglobin/hematocrit were measured before and immediately after HD.

RESULTS

QT decreased (380.9 +/- 38.4-363.5 +/- 36.8 ms, P = 0.001), the QTc did not change (406.2 +/- 30.8-405.4 +/- 32.2 ms, P = 0.8), the QTd increased (31.3 +/- 14.6-43.9 +/- 18.6 ms, P = 0.003), and the SigmaT decreased (32.3 +/- 15.7-25.9 +/- 12.6 mm, P = 0.0001) after HD. There was no correlation between the change in QTd and the changes in serum cations, heart rate, the subjects' weight, T-wave duration, and SigmaT. However, the change in QTc correlated inversely with the change in serum Ca(++) (r =-0.339, P = 0.021).

CONCLUSION

QTd increased, the SigmaT decreased, and the QTc and T-wave duration remained stable, after HD. The QTd increase, although may be real, could also reflect measurement errors stemming from the decrease in the amplitude of T waves (as shown recently), imparted by HD; this requires clarification, to use QTd in patient on HD.

Low Voltage ECG in Myocarditis: Peripheral Edema as a Plausible Contributing Mechanism

A 24-year-old woman was hospitalized with acute myocarditis that led to multiple organ, including heart, failure, with fluid retention. An echocardiogram showed left ventricular ejection fraction approximately 10%, and her electrocardiogram (ECG) revealed low voltage. She rapidly recovered and was discharged 15 days after admission. On evaluation at 1, 10, and 22 weeks after discharge, she was asymptomatic, with unlimited exercise tolerance. An echocardiogram 11 weeks after discharge from the hospital showed left ventricular ejection fraction of approximately 60%. Correlations of weights with ECG QRS voltage parameters in the hospital revealed r = 0.80 and 0.83, with P = 0.021 and 0.029, suggesting that >or=64% of the attenuation of the QRS potentials could be accounted for by the corresponding gain in weight.

P-wave and QRS complex measurements in patients undergoing hemodialysis

Hemodialysis (HD) has been associated with an increase in the amplitude of QRS complexes. Experience in a single patient with multiple measurements has shown that HD leads also to augmentation of P-wave amplitude. The objective of this investigation was to evaluate electrocardiogram (ECG) changes with HD in a cohort of patients undergoing this procedure with particular emphasis on the P-wave and QRS complex changes. The sum of amplitudes of P waves (OP) and QRS complexes (OQRS) in millimeters in the 12 leads of the ECG, along with a host of other ECG parameters, body weight, blood pressure, heart rate, electrolytes, and hemoglobin/hematocrit were measured before and immediately after HD in 47 patients. Hemodialysis resulted in a loss of a mean of 3 kg of weight and an increase in the SigmaP, SigmaQRS, mean QRS duration, maximum P-wave duration, and P-wave duration measured in lead II, whereas the changes in mean P-wave and corrected QT interval durations were not statistically significant. Percentage change (Delta%) in SigmaP and SigmaQRS correlated poorly with Delta% in electrolytes, hematocrit, blood pressure, heart rate, and weight. Values for SigmaP and SigmaQRS vs weight were r = 0.105, P = .48 and r = 0.09, P = .51, respectively. The Delta% in SigmaP correlated well with Delta% in SigmaQRS (r = 0.42, P = .003). Alterations in P-wave amplitudes and duration commensurate with the ones affecting the corresponding QRS complexes occur in patients undergoing HD and indicate that evaluation of measurements in serial ECGs should take this into account. The mechanisms of these phenomena continue to be elusive, and whether they represent cardiac and/or extracardiac influences has not as yet been unraveled.

Reversible attenuation of voltage of QRS complexes and P waves and shortening of QRS duration and QTc interval consequent to large perioperative intravenous fluid infusions

A 39-year-old woman with a gangrenous pyelonephritis and septic shock underwent a nephrectomy, in preparation for which, she received large preoperative fluid resuscitation. Quantitative evaluation of her serial standard electrocardiograms (ECGs) revealed reversible attenuation of voltage in association with peripheral edema (PERE), with the latter being eventually completely abolished. The transient low-voltage ECG (LVECG) (attenuated amplitudes of QRS complexes) was associated with parallel transient attenuation of the amplitude of P waves and shortening of the QRS duration and QTc, whereas the P-wave duration increased. Awareness of these ECG changes with PERE of varying pathophysiologic mechanisms is useful, ensuring avoidance of improper procedural and laboratory testing and correct measurement of wave amplitudes and ECG time intervals for proper ECG diagnosis. In addition, these ECG associations can be used as indices of the presence and course of PERE postoperatively, as well as in a large variety of medical settings.

ECG Changes in Response to Diuresis in an Ambulatory Patient With Congestive Heart Failure

This case report describes an ambulatory patient with congestive heart failure and peripheral edema who lost 18 lb in response to enhanced diuresis over the course of 1 week. The ECG showed increases in the amplitude of P waves, QRS complexes, and T waves; the duration of P waves, QRS complexes, and QT intervals; and the dispersion of P and QT. The clinical implications of these ECG changes are discussed.

Reversible Attenuation of the ECG Voltage Due to Peripheral Edema Associated With Treatment With a COX-2 Inhibitor

A 74-year-old man developed peripheral edema as a side effect of the cyclooxygense-2 selective receptor inhibitor rofecoxib, which he had been taking for severe chronic arthritis. Discontinuation of rofecoxib led to augmentation of electrocardiographic (ECG) voltage and loss of weight gain (and reversibility of peripheral edema), which correlated well (r=0.82; p=0.0002). Other good correlations of the weight and other ECG variables and intercorrelations of ECG parameters underscore the multiple reversible influences peripheral edema has on the ECG. This case highlights an enhanced role of the ECG in monitoring patient therapy with other than strictly cardiovascular drugs. Recently, a syndrome pertaining to the influence of peripheral edema on the ECG was described; its mechanism is via the transforming effect of the body volume conductor on the surface transfer of the heart's potentials. The objective of this report is to describe a patient who developed peripheral edema as a side effect of a cyclooxygenase-2 selective receptor inhibitor.

Standard Electrocardiographic and Signal-Averaged Electrocardiographic Changes in Congestive Heart Failure

A 54-year-old man with congestive heart failure and peripheral edema was monitored during treatment with serial electrocardiograms (ECGs) and two signal-averaged ECGs. Weights and a host of ECG parameters were monitored. ECGs recorded in the 5 years before his index admission were also considered in the quantitative ECG analysis. Amelioration of his peripheral edema was associated with reduction of his weight and increase in the QRS and P-wave amplitudes, and duration in QRS complexes and QT intervals in the ECGs, but unchanged signal-averaged ECGs. This case report provides insight into the mechanism of the change in QRS duration in ECGs during changing edematous states resulting from clinical deterioration or improved compensation in patients with congestive heart failure.