Polymorphic Ventricular Tachycardia—Part I: Structural Heart Disease and Acquired Causes

"Ion-Flux": The natural course of ECG changes in severe hypokalemia

Whereas the electrocardiogram (ECG) changes in hypokalemia are well known, they often receive less attention than the more striking features of hyperkalemia. Furthermore, there is a need for further discussion as to the subtleties of ECG changes that can aid in the differential diagnoses. This case study presents the ECG changes of a patient with severe hypokalemia due to diarrhea. It highlights how bifid T-waves in hypokalemia can be distinguished from other conditions such as coronary artery disease or pericarditis. Furthermore, it also shows the gradual reversal of ECG changes in the same patient when potassium is normalized.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Polymorphic Wide QRS Complex Tachycardia: Differential Diagnosis

Polymorphic wide QRS complex tachycardia is defined as a tachyarrhythmia showing variable and frequently alternating morphologies of the QRS complex with irregular R-R intervals. It may present with a specific and reproducible pattern including torsade de pointes and bidirectional ventricular tachycardia or with a nonspecific and very irregular pattern, different from ventricular fibrillation. Polymorphic ventricular tachycardia is a challenging diagnosis and is associated with a high risk for sudden cardiac death. Although rare, preexcited atrial fibrillation over multiple accessory pathways can also generate a polymorphic wide QRS complex tachycardia mimicking polymorphic ventricular tachycardia.

Nonsustained Ventricular Tachycardia in the Normal Heart: Risk Stratification and Management

Nonsustained ventricular tachycardia (NSVT) may trigger concern, particularly in patients with known congestive heart failure, structural heart disease, or prolonged QT interval. When NSVT occurs in patients with normal hearts, it usually has a benign prognosis. Therefore, establishing the presence or absence of structural or inherited heart disease is a critical step in each patient's evaluation. It is important to approach a wide-complex tachycardia in a systematic manner, to ensure correct diagnosis and treatment. When NSVT occurs in a patient with a normal heart, treatment is targeted toward symptoms and may consist of observation, medical therapy, or catheter ablation.

Pro-arrhythmogenic effects of CACNA1C G1911R mutation in human ventricular tachycardia: insights from cardiac multi-scale models

Mutations in the CACNA1C gene are associated with ventricular tachycardia (VT). Although the CACNA1C mutations were well identified in patients with cardiac arrhythmias, mechanisms by which cardiac arrhythmias are generated in such genetic mutation conditions remain unclear. In this study, we identified a novel mechanism of VT resulted from enhanced repolarization dispersion which is a key factor for arrhythmias in the CACNA1C G1911R mutation using multi-scale computational models of the human ventricle. The increased calcium influx in the mutation prolonged action potential duration (APD), produced steepened action potential duration restitution (APDR) curves as well as augmented membrane potential differences among different cell types during repolarization, increasing transmural dispersion of repolarization (DOR) and the spatial and temporal heterogeneity of cardiac electrical activities. Consequentially, the vulnerability to unidirectional conduction block in response to a premature stimulus increased at tissue level in the G1911R mutation. The increased functional repolarization dispersion anchored reentrant excitation waves in tissue and organ models, facilitating the initiation and maintenance of VT due to less meandering rotor tip. Thus, the increased repolarization dispersion caused by the G1911R mutation is a primary factor that may primarily contribute to the genesis of cardiac arrhythmias in Timothy Syndrome.

Echocardiographic pattern of acquired heart diseases in Nigeria

Background:

Acquired heart diseases (AHDs) are present from childhood to old age, and the frequency of pathology differs according to age and the geographical region of the patients. The aim of this study was to document the echocardiographic patterns of AHDs in our setting.

Materials and Methods:

Retrospective analysis of echocardiographic diagnosis of AHD was done for age, sex, and echocardiographic pattern.

Results:

There were 190 diagnoses in the 163 patients with 27 patients having a double diagnosis, consisting of 88 (54%) males and 75 (46%) females. The mean age was 50.4 years (age range 9-85 years). Ten types of acquired heart pathologies were identified and they included hypertensive heart disease in 49.47%, rheumatic heart disease in 26.32%, cardiomyopathy in 11.05%, endomyocardial fibrosis in 4.74%, and pericarditis in 3.68%. Others were cor pulmonale, pulmonary hypertension, intracardiac thrombi, left atrial myxoma and degenerative heart disease which accounted for the remaining 4.74%.

Conclusion:

This study identifies 10 types of AHDs among the study population. The huge impact of hypertensive heart disease and rheumatic heart disease is a big indicator pointing to the existence of a sub-optimal level of healthcare in the country.