Dilatation mechanism of balloon angioplasty in children: assessment by angiography and intravascular ultrasound.

PURPOSE: Little information is available about the dilatation mechanism in children. This prospective study aimed to (1) evaluate the dilatation mechanism of balloon angioplasty in children with arterial stenosis, and (2) compare the morphological changes seen by intravascular ultrasound (IVUS) and angiography. METHODS: Twenty consecutive patients, who had undergone a total of 23 procedures, were examined before and immediately after balloon angioplasty with a 4.3 Fr, 30 MHz rotational tip IVUS system. The lesions for IVUS study had resulted from coarctation of the aorta in six patients, pulmonary arterial stenosis in five, Blalock-Taussig shunt stenosis in three, subclavian artery stenosis in two, renal artery stenosis in two, coronary artery stenosis in one and ductus arteriosus in one. RESULTS: Four distinctive morphological types were identified: type I with arterial stretching, type IIa with superficial tearing, type IIb with deep intimal-medial tearing, type III with flap formation, and type IV with dissection. The diameter of the narrowest site before and after balloon angioplasty increased significantly from 2. 1 +/- 1.4 mm to 4.6 +/- 3.4 mm (p < 0.001). Eighteen of the 23 angioplasty procedures (78%) were considered to be successful, with a dilatation ratio of more than 50%. In most patients with successful dilatation, non-stretch mechanisms such as tearing, flap formation, or dissection were found. The positive percent (70%) of non-stretch mechanisms seen by IVUS was significantly higher than the positive findings (39%) by angiography (Chi2 = 6.47, p < 0.02). CONCLUSIONS: Non-stretch morphology of the arterial wall may be a common mechanism of dilatation after balloon angioplasty in children with arterial stenosis. IVUS is a useful modality for evaluating the effectiveness of balloon angioplasty and the mechanism of dilatation in individual cases.

[Intraoperative assessment of the ascending aorta by echogram during the CABG operation for the prevention of cerebral infarction].

While coronary artery bypass grafting operations (CABG), we started to use the echogram to evaluate the ascending aorta intraoperatively from December 1993. During a period from January, 1990, to June, 1995, 379 patients were treated with CABG. Intraoperative echogram was used in 127 cases (group I) and 252 cases unused (group II). The sites of the aorta for evaluation were following: site of cannulation, aortic clamping, and proximal anastomosis respectively. Depending on the echographical findings the operative procedures were changed as required. The incidence of postoperative cerebral embolism in group I was 0.8% (one patient) and in group II, 2.4% (6 patients). Although no significant difference was found in the cohort, rate of incidence in the group II was high. There were 4 cases who had significant atheromatous lesions clearly evaluated by echogram, which were not detected by palpation. We conclude that the intraoperative assessment of the ascending aorta by echogram is beneficial in prevention of cerebral infarction.

Angiographic assessment of the stretch-recoil-gain relation after balloon coarctation angioplasty and its relation to late restenosis.

The effects of stretch and immediate recoil after balloon angioplasty were evaluated in 21 patients with coarctation of the aorta who underwent balloon coarctation angioplasty. A total of 28 procedures were performed in these patients, who ranged in age from 1 month to 17 years with a mean of 4.3 years. The systolic pressure gradient and coarcted diameter changed significantly from 42 +/- 22 to 14 +/- 9 mmHg (P < 0.0001) and from 4.0 +/- 1.7 to 6.1 +/- 2.0 mm (P < 0.001), respectively. Immediate recoil was responsible for the loss of 33% of the potentially achievable coarcted dimension. Recoil was determined mainly by the degree of arterial stretch. Gain increased exponentially with an increase in stretch. There was a narrow range of % stretch (60-80%) within which an effective diameter gain could be obtained. Both gain and stretch were the best predictors for late restenosis: patients with a larger immediate gain and stretch developed more restenosis. These results suggest that the stretch-recoil-gain relationship may be clinically important for evaluating the best predictor of late restenosis after balloon coarctation angioplasty.

[Preoperative assessment of aortic dissection by three-dimensional CT angiography].

In 21 patients with aortic dissection including 12 patients with acute aortic dissection, aortic lesions were evaluated preoperatively by newly developed three-dimensional CT angiography (3 D-CTA) using helical scan CT. Rapid and safe three-dimensional evaluation of aortic dissection was achieved with no complications. Three-dimensional structure of aortic dissection was well reflected in the image of 3D-CTA. Preoperative three-dimensional evaluation was useful to determine and proceed the operative procedure for the repair of aortic dissection. All patients were alive and results of surgical treatments were excellent. Intimal flaps and entries were visualized by multiple threshold display (MTD) method of 3D-CTA. Multiple threshold display method is an important three-dimensional reconstructive method and 3D-CTA may be a new useful and powerful diagnostic modality for aortic dissection.

Assessment of aortic disease using three-dimensional CT angiography.

The recently developed technique of three-dimensional CT angiography (3D-CTA) was applied to 68 patients with aortic disease. These patients were examined using a unique method of data collection: a helical scanner with continuous tube rotation and continuous table feed. The scanner was used in conjunction with administration of dynamic intravenous contrast material to enhance the vascular image. The group of patients included 35 with aortic dissection, 19 with true thoracic aneurysms, and 14 with abdominal aortic aneurysms. Three-dimensional evaluation was achieved in all patients with no complications. Surgical intervention was used in 45 patients with aortic dissections and aortic aneurysms, and 44 of these patients (98%) survived and were discharged. Preoperative 3D-CTA findings were quite similar to intraoperative findings, and were useful in determining operative procedures. Rapid and accurate assessment of aortic disease was achieved by 3D-CTA. Three-dimensional CT angiography can play an important role in the preoperative assessment of aortic dissections and aortic aneurysms leading to successful surgical treatment.

Why are cadaveric renal transplants so hard to find in Japan? An analysis of economic and attitudinal aspects.

In view of the fact that in Japan treatment of end-stage renal disease depends disproportionately heavily on hemodialysis and almost negligible on transplants from cadaveric donors (hemodialysis 44.4/100,000; renal transplants 0.31/100,000 per year; cadaveric renal transplants 0.11/100,000 per year (1983 data)), we analysed the cost-effectiveness of hemodialysis and renal transplantation, predicted economic gains under expected changes in variables and described attitudes of the Japanese hampering cadaveric renal transplantation. Adjusted life expectancy of transplant recipients (live and cadaveric combined) under the current technical conditions is longer than that of those on hemodialysis (18.3 vs. 14.7 years) and the cost per year for maintaining the transplant is approximately one third of hemodialysis ($12,000 vs $32,000). If the proportion of cadaveric transplant recipients would increase to the levels of the USA (hemodialysis 30.8/100,000; transplants 2.6/100,000 per year; cadaveric transplants 1.9/100,000 per year (1983 data)) along with improvement in graft survival rate, the life expectancy for transplant recipients in Japan could increase by 2 years, thus reducing the annual cost even further. The current number of patients starting hemodialysis (11,500 cases per year) coupled with their life expectancy predicts the number of patients on hemodialysis to reach equilibrium at around 174,000 in a decade (Japanese population 110 million). Based on current price, their annual cost will be about 5.3 billion dollars. Medical expenditure of this magnitude for such a small fraction of people is expected to become an increasingly strong economic incentive for cadaveric renal transplantation. A review of studies on Japanese attitudes toward cadaveric renal transplantation in both urban and rural areas shows that approximately 60% are in favor of donating their kidney after death, though with the majority of cases the donation is contingent upon agreement of their family. It was suggested that the paucity of cadaveric kidney supply stems mainly from the custom of the Japanese to make decisions by consensus. It was also reported that more than 80% of physicians supported the donation of cadaveric grafts while this rate fell to 40% in case of brain death. As the first heart transplantation was carried out in 1968 under both medically and ethically dubious circumstances, distrust toward the diagnosis of brain death appears to be still quite strong. (Not a single heart transplantation has been attempted in Japan in the past 18 years).(ABSTRACT TRUNCATED AT 400 WORDS)