This scar cannot conduct electrical activity, so there is a potential circuit around the scar that results in the tachycardia. This is similar to the re-entrant circuits that are the cause of atrial flutter and the re-entrant forms of supraventricular tachycardia. Other rarer congenital causes of monomorphic VT include right ventricular dysplasia, and right and left ventricular outflow tract VT.Polymorphic ventricular tachycardia, on the other hand, is most commonly caused by abnormalities of ventricular muscle repolarization. The predisposition to this problem usually manifests on the ECG as a prolongation of the QT interval. QT prolongation may be congenital or acquired. Congenital problems include long QT syndrome and catecholaminergic polymorphic ventricular tachycardia. Acquired problems are usually related to drug toxicity or electrolyte abnormalities, but can occur as a result of myocardial ischemia. Class III anti-arrhythmic drugs such as sotalol and amiodarone prolong the QT interval and may in some circumstances be pro-arrhythmic. Other relatively common drugs including some antibiotics and antihistamines may also be a danger, in particular in combination with one another. Problems with blood levels of potassium, magnesium and calcium may also contribute. High-dose magnesium is often used as an antidote in cardiac arrest protocols. Diagnosis
The diagnosis of ventricular tachycardia is made based on the rhythm seen on either a 12-lead ECG or a telemetry rhythm strip. It may be very difficult to differentiate between ventricular tachycardia and a wide-complex supraventricular tachycardia in some cases. In particular, supraventricular tachycardias with aberrant conduction from a pre-existing bundle branch block are commonly misdiagnosed as ventricular tachycardia.
However, working memory problems are confounded with domain-general learning difficulties, thus these deficits may not be specific to dyscalculia but rather may reflect a greater learning deficit. Dysfunction in prefrontal regions may also lead to deficits in working memory and other executive function, accounting for comorbidity with ADHD.Studies have also shown indications of causes due to congenital or hereditary disorders, but evidence of this is not yet concrete. Treatment
To date, very few interventions have been developed specifically for individuals with dyscalculia. Concrete manipulation activities have been used for decades to train basic number concepts for remediation purposes. This method facilitates the intrinsic relationship between a goal, the learners action, and the informational feedback on the action. A one-to-one tutoring paradigm designed by Lynn Fuchs and colleagues which teaches concepts in arithmetic, number concepts, counting, and number families using games, flash cards, and manipulables has proven successful in children with generalized math learning difficulties, but intervention has yet to be tested specifically on children with dyscalculia. These methods require specially trained teachers working directly with small groups or individual students. As such, instruction time in the classroom is necessarily limited. For this reason, several research groups have developed computer adaptive training programs designed to target deficits unique to dyscalculic individuals.Software intended to remediate dyscalculia has been developed. While computer adaptive training programs are modeled after one-to-one type interventions, they provide several advantages. Most notably, individuals are able to practice more with a digital intervention than is typically possible with a class or teacher.