Question

13. A patient comes to the hospital imaging lab where you work. The patient suffers from a rare genetic condition in which the contractile cells of her heart have limited conductivity. You are asked to perform an ultrasound or echocardiogram of the patient’s heart. As you view the video monitor, what would you expect to observe about the patient’s heart function as you view and analyze the contracting?

Answer 1

Cardiac conduction disease (CCD) :

It is a serious disorder of the heart. If CCD is of an inherited nature (ICCD), its underlying mechanism can be either structural, functional or there can be overlap between these two mechanisms.

If ICCD is structural in nature, it is often secondary to anatomical or histological abnormalities of the heart. Functional ICCD is frequently found as a “primary electrical disease” of the heart, i.e. resulting from functionally abnormal, or absent proteins encoded by mutated genes, often cardiac ion channel proteins involved in impulse formation.

The cardiac conduction system enables fast and co-ordinated contraction of the heart. It is composed of specialized cardiac structures that are responsible for impulse formation and propagation.

The cardiac impulse is generated by the sinus node in the right atrium, and is conducted to the left atrium via the Bachmann bundle. From the atria, electrical activity is transmitted to the ventricular myocardium through the atrioventricular node, the bundle of His, the right and left bundle branches, and the Purkinje fibre network successively, to ensure synchronized contraction of the heart.

• Macro- or microscopical structural abnormalities in CCD may occur at any level in the conduction system and disrupt normal impulse propagation. These structural abnormalities may range from partial or total absence of structures, to gradual replacement of the normal tissues by fatty and/or fibrous tissue and calcification.
• The familial primary electrical diseases of the heart, that occur in the absence of structural heart disease or systemic disease, result from mutations in cardiac ion channel genes and associated or modifying proteins, such as cytoskeletal proteins

Analysis in ECG:

Long QT Syndrome (LQTS)

Explaining the problem

Long QT Syndrome, also called LQTS, is a disorder of the heart’s electrical system, like other arrhythmias.

In LQTS, the lower chambers of the heart (ventricles) take too long to contract and release. The gap of time needed to complete a cycle can be measured and compared to normal averages.

The name for the condition comes from letters associated with the waveform created by the heart’s electrical signals. The interval between the letters Q and T defines the action of the ventricles. Hence, Long QT Syndrome means that time period is too long, even if by fractions of a second.