Patent ductus arteriosus (PDA) is a common congenital heart defect. PDA disproportionately affects low-birth-weight infants, resulting in an incidence of 21% among preterm births as compared to 0.05% in the general population. The ductus arteriosus remains patent in the fetus, allowing maternal blood to directly enter fetal systemic circulation, bypassing the fetal lungs. This is mediated through the mechanisms of nitric oxide and prostaglandins. At birth, increased partial pressure and decreased prostaglandin levels facilitate functional closure of the ductus arteriosus. Further migration of contractile smooth muscle cells and tissue remodeling results in fibrosis and anatomical closure of the ductus. Underdevelopment of contractile smooth muscle cells, the intimal layer in blood vessels, and vasa vasorum have been theorized as the mechanisms behind PDA in preterm-birth neonates. PDA creates a left-to-right shunt, sending oxygenated blood from the aorta to the lungs via the pulmonary artery, often manifesting with symptoms of pulmonary hypertension and edema. As the symptoms progress, the shunt is often reversed, resulting in cyanosis in a condition known as Eisenmenger syndrome. While most affected patients present with distinguishing clinical findings, many also remain asymptomatic, and the defect goes undetected for years.
Rithvik Swamynathan, L. Dolan, William H. Frishman et al.· Cardiology in Review· 0 citations
Aortic stenosis (AS) is the most common degenerative valvular disease in elderly patients and is linked to high morbidity and mortality. Accurate diagnosis and risk stratification are critical for effective management. Transthoracic echocardiography is the standard diagnostic tool, but its reliance on flow-dependent parameters can lead to inconsistent grading, especially in low-flow, low-gradient, or normal-flow, low-gradient AS. Advanced echocardiographic methods, such as 3D imaging, stress echocardiography, and Doppler indices, such as the mean gradient-to-effective orifice area ratio, improve the evaluation of AS severity and assist in clinical decision-making. Computed tomography provides a flow-independent evaluation of AS. It uses noncontrast calcium scoring with sex-specific thresholds, along with contrast-enhanced angiography, for detailed anatomical assessment. These modalities are essential for procedural planning, particularly for transcatheter aortic valve replacement. Cardiac magnetic resonance (CMR) provides additional prognostic information. It quantifies myocardial remodeling and fibrosis, which are associated with outcomes and recovery potential. Emerging technologies are expanding diagnostic capabilities in AS. Examples include 18F-sodium fluoride positron emission tomography for detecting microcalcification, artificial intelligence-based ECG and echocardiography for early diagnosis, and 4D flow CMR. Integration of echocardiography, computed tomography, CMR, and emerging positron emission tomography and artificial intelligence-based approaches can help address diagnostic uncertainty. This integration helps refine AS subtype classification and inform individualized intervention strategies.
H. Itani, M. Moumneh, A. Zayed et al.· Cardiology in Review· 0 citations