Dissecting Aneurysm of the Main Pulmonary Artery

Abstract

Since the first introduction of pulmonary balloon valvuloplasty by Kan in 1982, the procedure has been used for relief of pulmonary valve stenosis. It is normally recommended that the procedure should be performed for peak-topeak gradients in excess of 50 mm Hg, 1 and the balloon/ annulus ratio should be 1.2 to 1.25 for effective and safe results. 2 Complications of the procedure are minimal and rare. We present the case of dissecting aneurysm of the main pulmonary artery, a dangerous complication of pulmonary balloon valvuloplasty performed in a child, which was successfully treated with surgical management.A 4-year-old boy was admitted to our hospital in December, 2007, whose history included 2 years of 4/6 systolic murmur heard over the pulmonary artery. The transthoracic echocardiogram showed severe pulmonary valve stenosis, and the Doppler-measured peak instantaneous gradient was 121 mm Hg, which was the indication for pulmonary balloon valvuloplasty. A 6F Mansfield balloon catheter was used (18/30 mm, balloon-to-annulus ratio 1.15). The catheterization-measured peak-to-peak gradient was 125 mm Hg. Manual inflation was performed until the balloon indentation disappeared, and 2 additional inflations were performed. After the inflations, the transvalvular pressure gradient was reduced to 28 mm Hg. The patient was observed in an intermediate care setting overnight, with monitoring of heart rate, pulse oximetry, blood pressure, pulses, and puncture site for bleeding. An echocardiogram performed on the morning after the procedure showed the transvalvular pressure gradient was 26 mm Hg, and no complications were revealed. The patient was asymptomatic.At follow-up 1 month later, the patient was still asymptomatic, but a 3/6 systolic murmur was heard over the pulmonary artery. Transthoracic x-ray examination showed the main pulmonary artery to be more dilated than before the valvuloplasty (Figure 1). A transthoracic echocardiogram showed a peak-to-peak gradient of 37 mm Hg and main pulmonary artery dissection (Figure 2). The obvious dilatation of the main pulmonary artery was noted, and a long, freely moving, intimal flap from the stenotic pulmonary valve to the crotch of the main pulmonary artery was revealed. The intimal flap separated the main pulmonary artery into a small true lumen and a large false lumen (32ϫ58 mm), and it also interfered with the motion of the pulmonary valvar leaflets and the blood flow of the left and right pulmonary arteries. The blood supply of right pulmonary artery was through the true lumen, whereas that of the left pulmonary artery was through a small break on the intimal flap. Computed tomography (CT) examination and a multislice CT scan confirmed the dissection and the presence of the dissecting aneurysm (Figure 3, Figure 4, and Figure 5).Because the dissecting aneurysm was very big and affected the normal pulmonary blood flow, and even though it was asymptomatic, the patient required surgery. After longitudinal incision of the main pulmonary artery, the situation of the pulmonary ...

Molecular Pathways of Notch Signaling in Vascular Smooth Muscle Cells

“…A variety of mechanisms have been proposed to explain the discrepant phenotypes in VSMC upon activation of Notch signaling. For example, it is well documented that endothelial expression of Jag-1 is required for activation of Notch3 on VSMC and maintenance of VSMC maturation and contraction (High et al, 2008; Liu et al, 2009), while others have shown a variety of mechanisms by which active Notch signaling inhibits VSMC differentiation and the contractile phenotype (Havrda et al, 2006; Li et al, 2009a). Work from our laboratory supports the former finding in that activation of Notch receptors in human primary VSMC using immobilized Jag-1 promotes upregulation of contractile proteins (Boucher et al, 2011; Figure 3A).…”

“…Support for the involvement of Notch in mediating VSMC proliferation and neointimal formation comes from a study in which carotid artery ligations were used to induce the formation of a neointima in mice harboring one of the following genotypes: a general heterozygous deletion of Notch1 (Notch1 +/− ), a VSMC specific heterozygous deletion of Notch1 (VSMC–Notch1 +/− ), or a homozygous general deletion of Notch3 (Notch3 −/− ; Li et al, 2009a). In this report, researchers show negligible differences in neointimal formation between wild type and Notch3 −/− , while Notch1 +/− and VSMC–Notch1 +/− resulted in post-carotid ligation decrease in neointimal lesion formation by 70%.…”

Rare Presentation of Left Lower Lobe Pulmonary Artery Dissection

“…Treatment of pulmonary artery dissection is surgical in case of symptomatic patients [14]. Nonoperative treatment is reserved for stable asymptomatic patients [15, 16].…”

Pulmonary Artery Dissection: A Fatal Complication of Pulmonary Hypertension

“…Pulmonary artery dissection is suspected in the face of sudden hemodynamic decomposition in an otherwise previously stable patient with known presentation of pulmonary hypertension or pulmonary artery aneurysm [13]. The condition progresses rapidly, so prompt diagnosis permits surgical treatment, which improves prognosis [14, 15]. Fortunately, several imaging modalities, such as chest radiograph, echocardiography, CT angiography, MRI, and cardiac catheterization, have been available for the evaluation of pulmonary artery dissection.…”

“…There is no definite guideline as the optimal treatment for pulmonary artery dissection. Surgical intervention may be necessary for most patients but it is usually followed by fatal consequences [12, 14]. Unfortunately, this patient suddenly died before surgical intervention.…”