Angiographic, intravascular ultrasound and functional findings early after orthotopic heart transplantation

Invasive echocardiography: the use of catheter imaging by the interventional cardiologist

Ultrasound imaging is frequently used for diagnostic purposes or guidance during procedures in the pediatric and congenital cardiac catheterization laboratory. As new imaging modalities emerged, many interventional cardiologists rather than noninvasive specialists are now performing the ultrasound imaging as part of the catheterization. The focus of this discussion will be to detail the technique and application of echocardiography by the interventional cardiologist.

Impact of lipid abnormalities in development and progression of transplant coronary disease: a serial intravascular ultrasound study

OBJECTIVES

We sought to determine the role of conventional atherosclerosis risk factors in the development and progression of transplant coronary artery disease (CAD) using serial intravascular ultrasound imaging.

BACKGROUND

Transplant artery disease is a combination of allograft vasculopathy and donor atherosclerosis. The clinical determinants for each of these disease processes are not well characterized. Intravascular ultrasound imaging is the most sensitive tool to serially study these processes.

METHODS

Baseline intravascular ultrasound imaging was performed 0.9 +/- 0.5 months after transplantation to identify donor atherosclerosis. Follow-up imaging was performed at 1.0 +/- 0.07 year to evaluate progression of donor atherosclerosis and development of transplant vasculopathy. Conventional risk factors for CAD included recipient age, gender, smoking history, diabetes mellitus, hypertension and hypercholesterolemia.

RESULTS

Donor-transmitted atherosclerosis was present in 36 patients (39%). At follow-up, progression of donor lesions was seen in 15 patients (42%) and 42 patients (45%) developed transplant vasculopathy, leaving 35 patients (38%) without any disease. There was no difference in any conventional risk factors in patients with and without allograft vasculopathy. However, the severity of allograft vasculopathy was associated with a larger increase in low density lipoprotein (LDL) cholesterol from baseline (p = 0.02). High one-year posttransplant serum triglyceride level and pretransplant body mass index were the only significant predictors (p = 0.03) for progression of donor atherosclerosis.

CONCLUSIONS

Conventional atherosclerosis risk factors do not predict development of allograft vasculopathy, but greater change in serum LDL cholesterol level during the first year after transplant is associated with more severe vasculopathy. Therefore, maintenance of LDL cholesterol as close to pretransplant values as possible may help to limit the rate of progression of acquired allograft vasculopathy.

The medium-term findings in coronary arteries by intravascular ultrasound in infants and children after heart transplantation

OBJECTIVES

The study purposes were to determine 1) whether intravascular ultrasound (IVUS) was more sensitive than angiography for the detection of post-transplant coronary artery disease (PTCAD) in pediatric patients; and 2) whether those transplanted as neonates reacted differently than older patients.

BACKGROUND

Experience with IVUS for the diagnosis of PTCAD in children is limited.

METHODS

Patients were divided into two groups: those transplanted as neonates (early group) and those transplanted in infancy or childhood (late group). Morphometric analysis was performed, including maximal intimal thickness (MIT) and intimal index (II). Stanford classification was used to grade lesion severity. Acute rejection and cytomegalovirus (CMV) status were correlated with MIT and II.

RESULTS

Thirty children were studied (early group, n = 13; late group, n = 17). All segments studied were angiographically normal. Mean MIT and mean II were significantly greater in the late group (0.26 +/- 0.14 vs. 0.13 +/- 0.04 mm, p < 0.001 and 0.11 +/- 0.07 vs. 0.07 +/- 0.03 mm, p = 0.04, respectively). There was a significant correlation between MIT and II in those who had acute rejection in the late group. Patients in the late group who were CMV-positive had a significantly higher MIT compared with those in the late group with negative serology (p = 0.04).

CONCLUSIONS

Intravascular ultrasound was more sensitive than angiography in detecting PTCAD after pediatric heart transplantation. There is a possible role for acute rejection and CMV in the development of PTCAD.

Impact of intravascular ultrasound in understanding transplant coronary artery disease

Intravascular ultrasound imaging has been recognized as a sensitive tool to study early transplant vasculopathy lesions. An early examination performed soon after transplantation allows one to study donor atherosclerosis. Further, serial follow-up imaging with meticulous site matching provides important information regarding the progression of donor atherosclerosis and the development of transplant vasculopathy lesions. This review highlights the contribution of intravascular imaging in understanding the transplant coronary artery disease. This review also outlines various methodologies employed by different investigators, and stresses the strengths and weaknesses of these methodologies for correct interpretation as well as comparison of data from different studies.

Nitric oxide synthase gene transfer to the vessel wall

A wide array of vascular disorders have been shown to benefit from gene therapy. Given the vasoprotective role that nitric oxide plays in the vasculature, it is understandable why gene therapy with the three different isoforms of nitric oxide synthase has been so successful. This review summarizes the current literature pertaining to nitric oxide synthase gene transfer to the vascular wall.

Inducible nitric oxide synthase suppresses the development of allograft arteriosclerosis

In cardiac transplantation, chronic rejection takes the form of an occlusive vasculopathy. The mechanism underlying this disorder remains unclear. The purpose of this study was to investigate the role nitric oxide (NO) may play in the development of allograft arteriosclerosis. Rat aortic allografts from ACI donors to Wistar Furth recipients with a strong genetic disparity in both major and minor histocompatibility antigens were used for transplantation. Allografts collected at 28 d were found to have significant increases in both inducible NO synthase (iNOS) mRNA and protein as well as in intimal thickness when compared with isografts. Inhibiting NO production with an iNOS inhibitor increased the intimal thickening by 57.2%, indicating that NO suppresses the development of allograft arteriosclerosis. Next, we evaluated the effect of cyclosporine (CsA) on iNOS expression and allograft arteriosclerosis. CsA (10 mg/kg/d) suppressed the expression of iNOS in response to balloon-induced aortic injury. Similarly, CsA inhibited iNOS expression in the aortic allografts, associated with a 65% increase in intimal thickening. Finally, we investigated the effect of adenoviral-mediated iNOS gene transfer on allograft arteriosclerosis. Transduction with iNOS using an adenoviral vector suppressed completely the development of allograft arteriosclerosis in both untreated recipients and recipients treated with CsA. These results suggest that the early immune-mediated upregulation in iNOS expression partially protects aortic allografts from the development of allograft arteriosclerosis, and that iNOS gene transfer strategies may prove useful in preventing the development of this otherwise untreatable disease process.