In cardiology, ventricular dyssynchrony is a difference in the timing, or lack of synchrony, of contractions in different ventricles in the heart. Large differences in timing of contractions can reduce cardiac efficiency and is correlated with heart failure. Types of dyssynchrony
Three chief presentations of dyssynchrony can occur:
Atrioventricular (AV) dyssynchrony occurs when there is an unfavorable difference in timing between atrial and ventricular contractions. Interventricular dyssynchrony occurs when there is a difference in timing between right ventricular (RV) and left ventricular (LV) Systole. Intraventricular dyssynchrony occurs when the timing in a sequence of activations and contractions of segments of the LV wall becomes abnormal. In all three types, changes in timing lead to changes in the dynamic behavior of the myocardial tissues, leading to mechanical dyssynchrony. All three presentations allow distinct and easily reproducible electrical signatures as illustrated by left and right bundle branch blocks, hemiblocks, etc. The concise measurement of the time and morphology of the QRS interval allows the interventional ability to manipulate this interval with biventricular pacemakers. It is important to distinguish ventricular dyssynchrony from ventricular dyssynergy. Dyssynergy refers to changes in relative strength of contractions, whereas dyssynchrony is a change in relative timing of contractions. Once again the terms inotropy and chronotropy apply to the pathology under examination. Biventricular pacing strongly favors chronotropy over inotropy. Diagnosis
Echocardiography and tissue Doppler echocardiography are both needed to fully diagnose the different types of ventricular dyssynchrony. Treatment
Recent studies suggest that cardiac resynchronization therapy can reduce the incidence of ventricular dyssynchrony and thus increase cardiac efficiency.
The condition often impacts the formation of the knees, legs or feet that is sometimes addressed through surgery. For some with tightly webbed, bent knees or knees that are fused straight, disarticulation surgery at the knee may be a viable option to maximize mobility options.Before more comprehensive medical treatment was available, full amputation of the legs at the hip was often performed. More recently, the amputation (actually a disarticulation because no cutting of the bone is involved) is done at the knee for those who have bent knee positions and webbing between thigh and calf to enable more ease of mobility and better seating. Some children with knee disarticulation use prosthetic legs to walk. Prosthetics for children without substantial hip and trunk control is usually abandoned in favor of faster and easier wheelchair mobility as the childs weight and age increase. Children may walk on their hands and generally are able to climb and move about to accomplish whatever they need and want to accomplish. Children more mildly affected may have normal gait and no need for assistive devices for walking. Others may walk with bracing or crutches.There is typically no cognitive impairment associated with this disability. Adults with this disability live independently, attend college, and have careers in various fields. In 2012, Spencer West, a man with sacral agenesis and both legs amputated, climbed Mount Kilimanjaro using only his hands. In 2021, athlete Zion Clark broke the Guinness World Record 20m running on hands.