Superiority of the limb leads over the precordial leads on the 12-lead ECG in monitoring fluctuating fluid overload in a patient with congestive heart failure

Low QRS Voltage in Limb Leads Indicates Accompanying Precordial Voltage Attenuation Resulting in Underestimation of Left Ventricular Hypertrophy

Low QRS voltage (LQRSV) in electrocardiography (ECG) often occurs in limb leads without apparent cause. However, its clinical significance is obscure in healthy populations. We reviewed patients aged over 60 who were scheduled for non-cardiac surgery in two hospitals. Patients underwent pre-operative ECG, echocardiography, pulmonary function test, and chest X-ray. Patients with LQRSV isolated to limb leads and patients without LQRSV were selected from separate hospitals. Among the 9832 patients screened in one hospital, 292 (3.0%) showed LQRSV in limb leads. One-hundred and ninety-four without LQRSV were selected as the control from the 216 patients screened at the other hospital. For primary analysis, patients with structural heart disease or classic etiologies of LQRSV were excluded. Patients with LQRSV had a higher proportion of male and a greater body mass index. Precordial QRS voltages were smaller, whereas left ventricular mass index and the prevalence of echocardiographic left ventricular hypertrophy (LVH) was higher in patients with LQRSV than in those without. Consequentially, diagnostic performance of precordial voltage criteria for LVH was particularly poor in patients with LQRSV in limb leads. LQRSV in limb leads frequently occurs without apparent etiologies. ECG voltage criteria may underestimate LVH in a relatively healthy population with LQRSV in limb leads.

Relation of QRS Voltage and Prolonged QTc Interval to One-Year Mortality

The association between QRS voltage and QTc interval prolongation with mortality for up to 1 year after recording an ECG on patients attending emergency departments (EDs) was examined in a retrospective register-based observational study on 37,473 patients attending 2 Danish EDs. Of 37,473 patients who had an ECG performed on their first ED presentation 2,164 (5.8%) died within 30 days of presentation and 6,395 (17.1%) died within a year. Compared with survivors, patients who died had significantly longer QRS intervals and lower QRS voltages. A combined lead I and II QRS voltage <=1.4 mV was consistently associated with approximately twice the risk of mortality for up to at least 1 year after the ECG recording and this risk was not influenced by the length of the QTc interval. The increased mortality risk of a low QRS voltage remained even after adjustment for age, gender, Charlson co-morbidity index, and abnormal sodium and urea levels. In conclusion, low QRS voltage is a simple measurement that could potentially be used as an objective prognostic marker.

QRS voltage is a predictor of in-hospital mortality of acutely ill medical patients

BACKGROUND

Low QRS voltage has been shown to be associated with increased mortality in the general population and in a small pilot study the combined QRS voltage of ECG leads I and II was found to be associated with in-hospital mortality.

HYPOTHESIS

Confirm that low QRS voltage predicts the in-hospital mortality of acutely ill patients, and compare QRS voltage with other predictors of mortality that can be easily, quickly and cheaply obtained at the bedside.

METHODS

Prospective observational study of vital signs, QRS voltage and simple tools used to assess mental, functional and nutritional status at the bedside in unselected acutely ill patients admitted to a resource-poor hospital in sub-Saharan Africa.

RESULTS

Out of 1486 patients, 77 died (5.2%) in hospital. A combined lead I + II voltage <1.8 mV was present in 789 (53.1%) of patients, and significantly associated with in-hospital mortality (odds ratio 3.6, 95% CI 2.0-6.5, χ² 21.2, P < 0.00001). On logistic regression impaired mobility, the National Early Warning Score, male gender and lead I + II voltage were the only independent predictors of mortality. None of the 445 patients who were mobile on admission with a lead I + II voltage ≥ 1.8 mV died in hospital.

CONCLUSIONS

Low QRS voltage, male gender, NEWS, and impaired mobility were independent predictors of in-hospital mortality in the study population. These four variables, which are easily obtained at the bedside, could potentially provide a rapid, easy, and cheap risk stratification system.

A proposal for monitoring patients with heart failure via "smart phone technology"-based electrocardiograms

The ubiquitous smart phone/device technology (SPT) has enabled the safe acquisition/transmission (A/T) of clinical and laboratory patient data, including the electrocardiogram (ECG). SPT-based A/T of the ECG has been found useful in the detection of atrial fibrillation, in monitoring of the QTc interval, in patients undergoing antiarrhythmic drug loading, and in management of patients with acute ST-elevation myocardial infarction. Previous work has shown a relationship between changes in the voltage of the ECG QRS complexes, with perturbations in the edematous state of various etiologies, including heart failure (HF). It is proposed herein to employ serially SPT-based 3-lead ECG A/T for the monitoring and management of patients with HF in their ambient environment. The proposed method will enable patients with HF to acquire/transmit their 3-lead ECG to the caring HF team, using only their smart phone and it takes into consideration the advanced degrees of physical incapacitation and age-related infirmities inherent to the HF population.

Diagnosing Acute Heart Failure in the Emergency Department: A Systematic Review and Meta-analysis

BACKGROUND

Acute heart failure (AHF) is one of the most common diagnoses assigned to emergency department (ED) patients who are hospitalized. Despite its high prevalence in the emergency setting, the diagnosis of AHF in ED patients with undifferentiated dyspnea can be challenging.

OBJECTIVES

The primary objective of this study was to perform a systematic review and meta-analysis of the operating characteristics of diagnostic elements available to the emergency physician for diagnosing AHF. Secondary objectives were to develop a test-treatment threshold model and to calculate interval likelihood ratios (LRs) for natriuretic peptides (NPs) by pooling patient-level results.

METHODS

PubMed, EMBASE, and selected bibliographies were searched from January 1965 to March 2015 using MeSH terms to address the ability of the following index tests to predict AHF as a cause of dyspnea in adult patients in the ED: history and physical examination, electrocardiogram, chest radiograph (CXR), B-type natriuretic peptide (BNP), N-terminal proB-type natriuretic peptide (NT-proBNP), lung ultrasound (US), bedside echocardiography, and bioimpedance. A diagnosis of AHF based on clinical data combined with objective test results served as the criterion standard diagnosis. Data were analyzed using Meta-DiSc software. Authors of all NP studies were contacted to obtain patient-level data. The Quality Assessment Tool for Diagnostic Accuracy Studies-2 (QUADAS-2) for systematic reviews was utilized to evaluate the quality and applicability of the studies included.

RESULTS

Based on the included studies, the prevalence of AHF ranged from 29% to 79%. Index tests with pooled positive LRs ≥ 4 were the auscultation of S3 on physical examination (4.0, 95% confidence interval [CI] = 2.7 to 5.9), pulmonary edema on both CXR (4.8, 95% CI = 3.6 to 6.4) and lung US (7.4, 95% CI = 4.2 to 12.8), and reduced ejection fraction observed on bedside echocardiogram (4.1, 95% CI = 2.4 to 7.2). Tests with low negative LRs were BNP < 100 pg/mL (0.11, 95% CI = 0.07 to 0.16), NT-proBNP < 300 pg/mL (0.09, 95% CI = 0.03 to 0.34), and B-line pattern on lung US LR (0.16, 95% CI = 0.05 to 0.51). Interval LRs of BNP concentrations at the low end of "positive" results as defined by a cutoff of 100 pg/mL were substantially lower (100 to 200 pg/mL; 0.29, 95% CI = 0.23 to 0.38) than those associated with higher BNP concentrations (1000 to 1500 pg/mL; 7.12, 95% CI = 4.53 to 11.18). The interval LR of NT-proBNP concentrations even at very high values (30,000 to 200,000 pg/mL) was 3.30 (95% CI = 2.05 to 5.31).

CONCLUSIONS

Bedside lung US and echocardiography appear to the most useful tests for affirming the presence of AHF while NPs are valuable in excluding the diagnosis.

Comparison of electrocardiogram aVR QRS metrics, as indices of the sums of leads I and II, and all 6 limb leads

Electrocardiogram (ECG) peak-to peak amplitude (Pk-pk) of the limb leads, in the form of sums of leads I and II (I+II), or all 6 limb leads (Σ6Lblds), and lead aVR have been employed for the monitoring of patients with edematous states (ES), including heart failure (HF), or those undergoing hemodialysis (HD). The aim of this study was to compare aVR metrics (net QRS area [NQRSA], total QRS area [TQRSA], Pk-pk, and QRS root mean square [QRSRMS]) as indices of the corresponding metrics of I+II and Σ6Lblds. Automated measurements of the above metrics deriving from a set of randomly selected 1784 ECGs were compared and inter-correlated. NQRSA of aVR showed the best correlation with I+II (r=-0.99) and Σ6Lblds (r=-0.78), while Pk-pk the worst (r=0.68) and (r=0.62), correspondingly. NQRSA of aVR has advantages over Pk-pk, reflecting I+II or Σ6Lblds, and thus it might be employed in serial ECGs for the monitoring of patients with ES, including HF, and HD. However the present paper constitutes a methodological work, and thus the performance of NQRSA of aVR in monitoring patients with ES needs to be substantiated by a future study. Automated measurements of NQRSA of aVR are provided by many contemporary electrocardiographs upon recording of the ECG and could be put to use at the "point of care".

Care of the lower extremities in patients with acute decompensated heart failure

Patients with heart failure and pulmonary edema are often admitted to the critical care unit. Many of these patients have severe peripheral edema, which may be associated with exudates and wounds of the lower extremities and which present a challenge to critical care nurses. Little information is available on treatment of peripheral edema in the intensive care unit or in patients with unstable hemodynamic status. Nursing care is based on available evidence, findings on chest radiographs, and hemodynamic status. Medications that contribute to peripheral edema should be evaluated and discontinued if possible. An appropriate mattress surface with an underpad that promotes wicking away of moisture should be selected. The patient's lower extremities should be elevated according to his or her current pulmonary status, and skin-protective interventions should be instituted. Multilayer compression wraps should be avoided until the patient's hemodynamic status is stable and the patient can get out of bed.

aVR, an index of all ECG limb leads, with clinical utility for monitoring of patients with edematous states, including heart failure

BACKGROUND

Nonreproducibility of precordial electrocardiogram (ECG) leads in serial ECGs has led to emphasis on the limb leads for some applications. Since modern electrocardiographs measure leads I and II and calculate on line the other four limb leads, the former can substitute for the set of six limb leads. Furthermore, based on the mathematical relationship of lead aVR and leads I and II, it was hypothesized that aVR could be used as a representative index of the set of the six limb leads. The aim of this study was to evaluate whether ECG lead aVR could function as an index of all limb leads, in clinical electrocardiography.

METHODS

Automation-derived and manually derived QRS voltage amplitude measurements of all limb leads in ECGs of a series of 100 randomly selected consecutive patients, and ECGs of 36 patients with various edematous states (EDST), congestive heart failure (CHF), or undergoing hemodialysis (HD), and aVR were inter-correlated with the sums of leads I and II (SigmaI&II), and the entire set of the six limb leads (Sigma6LbLds).

RESULTS

Correlation of aVR with SigmaI&II and Sigma6LbLds was excellent (P < 0.00005); also, aVR was found to be a reliable index of the six limb leads in repeat ECGs in the patients with various EDST, CHF, or undergoing HD, in whom changes in aVR correlated with changes in patients' body weight.

CONCLUSION

aVR could be taken as an index of all ECG limb leads in analysis in general, and in monitoring patients with EDST, CHF, and HD in particular.