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Concept: QRS complex


According to current ESC Guidelines for the diagnosis and treatment of heart failure cardiac resynchronization therapy (CRT) is indicated in patients suffering from heart failure (HF) with reduced ejection fraction (EF) with significantly widened QRS complexes. Presence of vital myocardium proved by dobutamine stress echocardiography (DSE) is considered as a good prognostic factor for responsiveness to this treatment. Chronotropic incompetence is on the other hand known factor of unfavorable outcome in HF.

Concepts: Myocardial infarction, Cardiology, Heart failure, Ejection fraction, Echocardiography, Heart disease, QRS complex, Purkinje fibers


ST elevation (STE) on the electrocardiogram (ECG) may be due to acute myocardial infarction (AMI) or other nonischemic pathologies such as left ventricular aneurysm (LVA). The objective of this study was to validate 2 previously derived ECG rules to distinguish AMI from LVA. The first rule states that if the sum of T-wave amplitudes in leads V1 to V4 divided by the sum of QRS amplitudes in leads V1 to V4 is greater than 0.22, then acute ST-segment elevation MI is predicted. The second rule states that if any 1 lead (V1-V4) has a T-wave amplitude to QRS amplitude ratio greater than or equal to 0.36, then acute ST-segment elevation MI is predicted.

Concepts: Myocardial infarction, Atherosclerosis, Cardiology, Acute coronary syndrome, Ventricular fibrillation, Electrocardiography, QRS complex, Ventricular aneurysm


Background. Overdose with lipophilic drugs, such as amitriptyline, may cause cardiotoxicity in overdose. Severe poisoning can be resistant to traditional treatments. Intravenous lipid emulsion (ILE) has been recommended as a novel therapy for the treatment of such overdoses; however, a little is known about the effects of ILE-infusion on drug concentration and haemodynamics in the early/absorptive phase after oral poisoning. Method. Thirty minutes after oro-gastric administration of amitriptyline (70 mg/kg), either 20% intravenous lipid emulsion (ILE), 8.4% sodium bicarbonate or Hartmann’s solution was infused to anaesthetized and ventilated rodents (n = 10 per group). Heart rate, blood pressure, cutaneous ECG - QRS interval duration (QRS-d), and survival were serially recorded over 120 min. Blood drug concentrations were also collected during this period. Continuous variables were compared using one-way ANOVA. Results. ILE infusion significantly decreased the survival compared to other treatments (10% ILE vs 70% bicarbonate vs 70% Hartmann’s solution, p = 0.005). There was a gradual prolongation of QRS-d and fall in blood pressure over time compared to baseline (T0) measurement for both ILE and Hartmann’s solution treatments. This was associated with significantly increased blood AMI concentration with ILE treatment at T60, T90 and T120 min to the other treatments (p < 0.02). Conclusion. Administration of ILE early after oral amitriptyline overdose resulted in worse survival and no improvement in haemodynamics. In addition, blood amitriptyline concentrations were higher in the ILE-treated group. This suggests that either drug absorption from the gastrointestinal-tract was facilitated or drug redistribution was retarded when ILE was given early after oral poisoning.

Concepts: Intravenous fluids, Concentration, Chemistry, Drugs, Saturation, Lactic acid, Solution, QRS complex


Findings on electrocardiogram may hint that pulmonary embolism (PE) is present when interpreted in the proper context and lead to definitive imaging tests. However, it would be useful to know if electrocardiographic (ECG) abnormalities also occur in patients with pneumonia and whether these are similar to ECG changes with PE. The purpose of this investigation was to determine ECG findings in patients with pneumonia. We retrospectively evaluated 62 adults discharged with a diagnosis of pneumonia who had no previous cardiopulmonary disease and had electrocardiogram obtained during hospitalization. The most prevalent ECG abnormality, other than sinus tachycardia, was minor nonspecific ST-segment or T-wave changes occurring in 13 of 62 (21%). Right atrial enlargement occurred in 4 of 62 (6.5%). QRS abnormalities were observed in 24 of 62 (39%). Right-axis deviation and S(1)S(2)S(3) were the most prevalent QRS abnormalities, which occurred in 6 of 62 (9.7%). Complete right bundle branch block and S(1)Q(3)T(3) pattern occurred in 3 of 62 (4.8%). ECG abnormalities that were not present within 1 month previously or abnormalities that disappeared within 1 month included left-axis deviation, right-axis deviation, right atrial enlargement, right ventricular hypertrophy, S(1)S(2)S(3), S(1)Q(3)T(3), low-voltage QRS complexes, and nonspecific ST-segment or T-wave abnormalities. In conclusion, electrocardiogram in patients with pneumonia often shows QRS abnormalities or nonspecific ST-segment or T-wave changes. ECG findings are similar to ECG abnormalities in PE and electrocardiogram cannot assist in the differential diagnosis.

Concepts: Cardiology, Heart, Cardiac electrophysiology, Pulmonary artery, Ventricular fibrillation, Electrocardiography, Hyperkalemia, QRS complex


In this study, several electrocardiogram (ECG)-derived indices corresponding to both ventricular depolarization and repolarization were evaluated during acute myocardial ischemia in an experimental model of myocardial infarction produced by 40 min coronary balloon inflation in 13 pigs. Significant changes were rapidly observed from minute 4 after the start of coronary occlusion, achieving their maximum values between 11 and 22 min for depolarization and between 9 and 12 min for repolarization indices, respectively. Subsequently, these maximum changes started to decrease during the latter part of the occlusion. Depolarization changes associated with the second half of the QRS complex showed a significant but inverse correlation with the myocardium at risk (MaR) estimated by scintigraphic images. The correlation between MaR and changes of the downward slope of the QRS complex, [Formula: see text], evaluated at the two more relevant peaks observed during the occlusion, was r = -0.75, p < 0.01 and r = -0.79, p < 0.01 for the positive and negative deflections observed in [Formula: see text] temporal evolution, respectively. Repolarization changes, analyzed by evaluation of ST segment elevation at the main observed positive peak, also showed negative, however non-significant correlation with MaR: r = -0.34, p = 0.28. Our results suggest that changes evaluated in the latter part of the depolarization, such as those described by [Formula: see text], which are influenced by R-wave amplitude, QRS width and ST level variations simultaneously, correlate better with the amount of ischemia than other indices evaluated in the earlier part of depolarization or during the ST segment.

Concepts: Myocardial infarction, Atherosclerosis, Cardiology, Cardiac electrophysiology, Acute coronary syndrome, Ventricular fibrillation, Electrocardiography, QRS complex


QRS detection algorithms are needed to analyze electrocardiogram (ECG) recordings generated in telehealth environments. However, the numerous published QRS detectors focus on clean, clinical data. Here, a ‘UNSW’ QRS detection algorithm is described that is suitable for clinical ECG and also poorer quality telehealth ECG.

Concepts: Algorithm, Cardiac electrophysiology, Computer, Psychotherapy, Electrocardiography, QRS complex


Atrioventricular (AV) block has been extensively studied. However, conduction inside the myocardium in patients with AV block has not been reported. In this study, we aimed to demonstrate the presence of intramyocardial block in patients with AV block. Five consecutive patients with spontaneous high-grade AV block and Torsades de pointes (TdP) were prospectively studied with standard United States Catheter Instruments (USCI) endocardial temporary catheter located at the right ventricle (RV) apex. The morphology of endocardial potentials observed in the basic QRS complexes as well as during episodes of TdP was studied. The electrogram (EGM) of the basic rhythm showed a sharp deflection of high amplitude preceded and/or followed by a smooth potential of low amplitude interpreted as far-field potentials in all patients. The sharp potential can be observed at the beginning, in the middle or at the end of the smooth potential. All these potentials were reproduced from beat to beat and were falling inside the QRS complex of the surface ECG. Therefore, these aspects are zones of electrically depressed or silent myocardium larger than the interelectrode distance of 12 mm. This situation is in agreement with recent genetic factors. In this study, we demonstrated for the first time that patients with spontaneous AV block also have trouble in ventricular activation located on the AV conduction system and inside the myocardium. It is then possible to speculate that the presence of diffuse non-conducting myocardium explains why most TdPs do not degenerate into ventricular fibrillation (VF) and generally stop spontaneously.

Concepts: Myocardial infarction, Heart, Cardiac electrophysiology, Ventricular fibrillation, Sinoatrial node, Electrocardiography, QRS complex, Purkinje fibers


PR interval is the period from the onset of P wave to the start of the QRS complex on electrocardiograms. A recent genomewide association study (GWAS) suggested that GAREM1 was linked to the PR interval on electrocardiograms. This study was designed to validate this correlation using additional subjects and examined the function of Garem1 in a mouse model. We analyzed the association of rs17744182, a variant in the GAREM1 locus, with the PR interval in 5646 subjects who were recruited from 2 Korean replication sets, Yangpyeong (n = 2471) and Yonsei (n = 3175), and noted a significant genomewide association by meta-analysis (P = 2.39 × 10-8). To confirm the function of Garem1 in mice, Garem1 siRNA was injected into mouse tail veins to reduce the expression of Garem1. Garem1 transcript levels declined by 53% in the atrium of the heart (P = 0.029), and Garem1-siRNA injected mice experienced a significant decrease in PR interval (43.27 ms vs. 44.89 ms in control, P = 0.007). We analyzed the expression pattern of Garem1 in the heart by immunohistology and observed specific expression of Garem1 in intracardiac ganglia. Garem1 was expressed in most neurons of the ganglion, including cholinergic and adrenergic cells. We have provided evidence that GAREM1 is involved in the PR interval of ECGs. These findings increase our understanding of the regulatory signals of heart rhythm through intracardiac ganglia of the autonomic nervous system and can be used to guide the development of a therapeutic target for heart conditions, such as atrial fibrillation.

Concepts: Nervous system, Neuron, Ganglion, Gene expression, Heart, Atrial fibrillation, Genome-wide association study, QRS complex


Cardiac amyloidosis (CA) is relatively rare and frequently misdiagnosed. Other disorders presenting with increased left ventricular (LV) mass can mimic its diagnosis. This case illustrates unique findings of primary light chain (AL) amyloidosis in a patient with remarkable signs of CA. Here, we report a 49-year-old man with prior diagnosis of hypertrophy cardiomyopathy (HCM) based on an echocardiogram performed 1 year earlier that presented with 8 weeks of periorbital rash. He had numbness in the past 3 years. More recently, he presented with shortness of breath. Physical examination was remarkable for periorbital purpura, macroglossia, and orthostatic hypotension. Cardiac auscultation showed S3 and S4. Electrocardiography (ECG) showed diffuse low-voltage QRS complexes. Echocardiography revealed severe diastolic impairment; granular “sparkling” pattern of the myocardium with thickened walls, interatrial septum, and valves; and pericardial effusion. Diastolic dysfunction and thick walls with low ECG voltage are compelling diagnostic findings. Laboratory work up showed increased free light chain-differential (FLC-diff), N-terminal fragment of brain natriuretic peptide (NT-BNP), and cardiac Troponin T (cTnT). Bone marrow biopsy confirmed AL amyloidosis. A diagnosis of AL amyloidosis with cardiac involvement mimicking HCM was made. The patient died during hospitalization due to sudden cardiac death. This cases illustrates the importance of the combination of clinical, serological, electro- and echocardiographic findings to establish the diagnosis of CA.

Concepts: Bone, Blood, Cardiology, Troponin, Physical examination, Ventricular fibrillation, Electrocardiography, QRS complex


Intravenous procainamide and amiodarone are drugs of choice for well-tolerated ventricular tachycardia. However, the choice between them, even according to Guidelines, is unclear. We performed a multicentre randomized open-labelled study to determine the safety and efficacy of intravenous procainamide and amiodarone for the acute treatment of tolerated wide QRS complex (probably ventricular) tachycardia.

Concepts: Cardiology, Atrial fibrillation, Ventricular tachycardia, Amiodarone, Ventricular fibrillation, Acute accent, Tachycardia, QRS complex