Conduction abnormalities requiring permanent pacemaker (PPM) implantation remain a common finding after TAVI due to the close proximity of the atrioventricular conduction system to the aortic root. Balloon valvuloplasty
For infants and children, balloon valvuloplasty, where a balloon is inflated to stretch the valve and allow greater flow, may also be effective. In adults, however, it is generally ineffective, as the valve tends to return to a stenosed state. The surgeon will make a small incision at the top of the persons leg and proceed to insert the balloon into the artery. The balloon is then advanced up to the valve and is inflated to stretch the valve open. Heart failure
Acute decompensated heart failure due to AS may be temporarily managed by an intra-aortic balloon pump while pending surgery. In those with high blood pressure nitroprusside may be carefully used. Phenylephrine may be used in those with very low blood pressure. Prognosis
If untreated, severe symptomatic aortic stenosis carries a poor prognosis, with a 2-year mortality rate of 50-60% and a 3-year survival rate of less than 30%. Prognosis after aortic valve replacement for people  younger than 65 is about five years less than that of the general population; for people older than 65 it is about the same. Epidemiology
Approximately 2% of people over the age of 65, 3% of people over age 75, and 4% percent of people over age 85 have aortic valve stenosis.
In the late stages of the disease, patients have been noted to develop impaired coordination, overresponsive reflexes, and even seizures. MRI testing is used to study and diagnose patients with this disease. A study conducted on four patients with this disease yielded similar MRI results despite their slightly differing symptoms. Genetic testing can show whether or not the individual has a mutation in the MLC1 gene, which accounts for 75% of all cases. Management
There currently is not a known cure for this disease. However, there are treatment options to mitigate the effects of symptoms that come with this disease. The drug Carbamazepine is an anticonvulsant drug commonly used to treat seizures and nerve pain. A case with a 5-year-old girl indicated the ability of this drug to reduce the effects of seizures linked to this disease. Epidemiology
Most of the cases were studied in Turkish families who were part of consanguineous marriages (getting married to relatives or the “same blood”). Nonetheless, Megalencephalic leukoencephalopathy with subcortical cysts does not show genetic heterogeneity which means that there are no mutations in other loci expressing similar phenotypes. History
A series of cases with megalencephalic leukodystrophy were described by the Indian neurologist Bhim Sen Singhal (1933-)in 1991. However, it is sometimes referred to as Van der Knaap disease after the Dutch neurologist Marjo van der Knaap who described another series of cases with clinical and radiological features in 1995. References
External links

GeneReview/NIH/UW entry on Megalencephalic Leukoencephalopathy with Subcortical Cysts