Abdominal aortic dissection with acute mesenteric ischemia in a patient with Marfan syndrome

Dysfunction of endothelial and smooth muscle cells in small arteries of a mouse model of Marfan syndrome

BACKGROUND AND PURPOSE

Marfan syndrome, a connective tissue disorder caused by mutations in FBN1 encoding fibrillin-1, results in life-threatening complications in the aorta, but little is known about its effects in resistance vasculature.

EXPERIMENTAL APPROACH

Second-order mesenteric arteries from mice at 3, 6 and 10 months of age (n= 30) heterozygous for the Fbn1 allele encoding a cysteine substitution (Fbn1(C1039G/+)) were compared with those from age-matched control littermates.

KEY RESULTS

Stress-strain curves indicated that arterial stiffness was increased at 6 and 10 months of age in Marfan vessels. Isometric force measurement revealed that contraction in response to potassium (60 mM)-induced membrane depolarization was decreased by at least 28% in Marfan vessels at all ages, while phenylephrine (3 microM)-induced contraction was reduced by at least 40% from 6 months. Acetylcholine-induced relaxation in Marfan vessels was reduced to 70% and 45% of control values, respectively, at 6 and 10 months. Sensitivity to sodium nitroprusside was reduced at 6 months (pEC(50)= 5.64 +/- 0.11, control pEC(50)= 7.34 +/- 0.04) and 10 months (pEC(50)= 5.99 +/- 0.07, control pEC(50)= 6.99 +/- 0.14). Pretreatment with N(omega)-Nitro-L-arginine methyl ester (200 microM) had no effect on acetylcholine-induced relaxation in Marfan vessels, but reduced vasorelaxation in control vessels to 57% of control values. Addition of indomethacin (10 microM) and catalase (1000 U.mL(-1)) further inhibited vasorelaxation in Marfan vessels to a greater degree compared with control vessels.

CONCLUSIONS AND IMPLICATIONS

Pathogenesis of Marfan syndrome in resistance-sized arteries increases stiffness and impairs vasomotor function.

Unusual complication of superior mesenteric artery syndrome: spontaneous upper gastrointestinal bleeding with hypovolemic shock

Superior mesenteric artery (SMA) syndrome is an unusual form of duodenal obstruction. Complications of SMA syndrome may sometimes develop and are usually associated with marked gastric dilatation, although most complications can be corrected by supportive treatment. In this article, we report a case of severe SMA syndrome with hypovolemic shock in a 24-year-old man. Multidetector-row computed tomography with reconstructed images was performed to establish the diagnosis. Spontaneous gastrointestinal bleeding is an extremely uncommon complication of SMA syndrome, and emergent surgical intervention was unavoidable in our patient. To our knowledge, no other such case has been reported in the English-language literature.

Lenticular subluxation in a patient with homocystinuria undetected by neonatal screening

A case of homocystinuria with lenticular subluxation was misdiagnosed as Marfan syndrome since the patient had no apparent mental impairment and had had a negative neonatal screen for homocystinuria. The delayed diagnosis of homocystinuria was due to a negative prior neonatal screen which was checked when he was a breastfed healthy newborn. In the absence of an autosomal dominant family history, and because of prior poor school performance, amino acid analysis and mutational analysis of the cystathionine beta-synthase gene were performed, which revealed the presence of homocystinuria. Low methionine diet with vitamin B6, folic acid, betaine, dipyridamole and aspirin was prescribed for emergency ophthalmologic surgery to prevent thromboembolic events. Fortunately, the operation was completed uneventfully. The patient has been followed-up for 4 years without any significant complaints under diet and medical control. Since homocystinuria is easily missed in neonatal screening programs, it should be suspected in patients who present with lenticular subluxation, even after a negative neonatal screen.