Morphological distinction of cervical nerve roots associated with motor function in 219 healthy volunteers: a multicenter prospective study.

STUDY DESIGN: A prospective study. OBJECTIVE: To examine the diameter (mm), transverse diameter (mm), and cross-sectional area (mm²) of the C5, C6, and C7 nerve roots using ultrasonography. SUMMARY OF BACKGROUND DATA: Each of the cervical nerve roots affected a different motor or sensory area. Although there were several studies that performed a detailed assessment of cervical nerve root anatomy in cadavers, only a few studies on the thickness of cervical nerve roots in living specimens have been performed. We examined whether the thickness of the C5, C6, and C7 nerve roots, as well as the area supplied by each of the roots, varied. METHODS: All 219 subjects (99 males and 120 females; mean age, 47 ± 15 yr) were healthy volunteers. The diameter and the transverse diameter were measured via ultrasonography, and the cross-sectional area was calculated for each of the C5-C7 nerve roots. RESULTS: The following diameter measurements (right and left, respectively) were obtained: C5, 2.8 and 2.9 mm; C6, 3.6 and 3.8 mm; and C7, 3.3 and 3.4 mm. The following transverse diameter measurements were obtained (right and left, respectively): C5, 2.8 and 3.0 mm; C6, 3.7 and 3.8 mm; and C7, 3.5 and 3.4 mm. The following cross-sectional area measurements (right and left, respectively) were obtained: C5, 6.3 and 6.4 mm²; C6, 10.7 and 11.0 mm²; and C7, 8.8 and 8.8 mm². Based on the 3 measurement methods, the C5 nerve root was significantly thinner than the other 2 nerve roots (P < 0.001), and the C7 nerve root was smaller than the C6 nerve root (P = 0.001). CONCLUSION: The C5 nerve root was significantly thinner than the C6 and C7 cervical nerve roots. The fact that the C5 nerve is thinner may render it more susceptible to damage during cervical surgery.

[Ventricular septal defect with right pulmonary agenesis and left bronchial stenosis].

We report a case of ventricular septal defect (VSD) with right pulmonary agenesis and left bronchial stenosis. Delivery of a male infant was uneventful. Birth weight was 3,050g. At 12 days of age, he presented himself with tachypnea and wheezing. Dextrocardia was noted on a chest X-ray. Computed tomography (CT) of the chest showed right pulmonary agenesis and severe narrowing of the left main bronchus. An echocardiogram showed VSD, patent ductus arteriosus (PDA) and pulmonary hypertension (PH). At 22 days of age, he was put on ventilator. At 1 month of age, pulmonary artery banding and division of PDA were performed through median sternotomy. At 5 months of age, weighing 5.0 kg, the VSD was closed with a Dacron patch through median sternotomy. At 6 months of age, tracheostomy was necessitated. At 1-year-old, he became free from ventilator.

Real-time studies of the pivot bearings in the NEDO Gyro PI-710 centrifugal blood pump.

The NEDO Gyro PI-710 centrifugal pump (Gyro PI-710 pump) incorporates a double pivot bearing system of which the male pivot and female bearings are fabricated from Al2O3 ceramic and ultrahigh molecular weight polyethylene. The top female bearing is a critical component because the impeller is levitated by hydraulic force and is maintained in the top contact position. A long-term in vitro examination of the pivot bearings was conducted using a biventricular assist model. In 7 animal experiments, the depth change of the top female bearing was examined. Animal experiments up to 90 days revealed that there was no noticeable depth increase in the top female bearing. According to the in vitro study, the life of the pivot bearings of the left and right pump was estimated to be approximately 3 and 7 years, respectively. Further improvement of this pivot bearing system is currently underway.

Development of a flexible inflow cannula with titanium inflow tip for the NEDO biventricular assist device.

A newly designed flexible inflow cannula has been developed for a biventricular assist device (BVAD). The inflow tip was designed for long-term ventricle drainage. Considering the anatomic differences between the right and left ventricles, a flexible inflow cannula, as a mass production model with a titanium tip, was developed and investigated in chronic BVAD animal experiments using the NEDO permanently implantable centrifugal blood pump. These flexible inflow cannulae consist of flexible plastic tubing with wire supported, titanium left and right tips. The right titanium inflow tip was designed with inner and outer stoppers to be inserted into the right ventricle wall and a beak shape to avoid sucking. The left tip was designed to be inserted into the left ventricle cavity. Five chronic BVAD bovine studies were performed to investigate the new beak shaped titanium tip. In these studies, the new beak shaped titanium tip and cannula prevented stenosis by a proliferation of pseudoneointimal, and supplied adequate blood flow to the pump without sucking. This newly designed inflow cannula with the beak shaped titanium tip was successfully implanted for 90 days.

Centrifugal blood pump with a hydraulically-levitated impeller for a permanently implantable biventricular assist device.

A permanently implantable biventricular assist device (BVAD) system has been developed with a centrifugal pump which is activated by a hydraulically-levitated impeller. The pump impeller floats hydraulically into the top contact position; this position prevents thrombus formation by creating a washout effect at the bottom bearing area, a common stagnant region. The pump was subjected to in vitro studies using a pulsatile mock circulation loop to confirm the impeller's top contact position and the swinging motion produced by the pulsation. Eleven in vivo BVAD studies confirmed that this swinging motion eliminated blood clot formation. Twenty-one pumps im-planted for up to three months did not reveal any thrombosis in the pumps or downstream organs. One exception was a right pump which was exposed to severe low flow due to the kinking of the outflow graft by the accidental pulling of the flow meter cable. Three ninety-day BVAD studies were achieved without thrombus formation.

Development of implantable right ventricular assist device.

Implantable ventricular assist devices (VADs) are indicated for long waiting periods before transplantation and also as a destination therapy. Meanwhile, right ventricular failure (RVF) is one of the four major complications observed in patients after left VAD (LVAD) implantation, with an incidence of approximately 20%. Preoperative prediction of the complication remains difficult, and the mortality is very high. To date, no implantable right VAD (RVAD) is available for the clinical situation. The possibility of realizing an implantable RVAD with Gyro centrifugal pump (PI-710 pump) was investigated. Eleven chronic animal experiments with LVAD and RVAD implantation were performed. Right heart bypass was established between right outflow and pulmonary trunk, and the pump was implanted in the preperitoneal space. The anatomic fit was good. The mean term of the experiments was 59 days, with excellent pump performance. Stable pulmonary hemodynamics and respiratory function were maintained during all of the experimental terms. No specific abnormal histologic findings of the lung were confirmed; however, tunica media hypertrophy was recognized in some cases. The PI-710 pump is feasible as a clinically implantable RVAD, but further study of histologic and pulmonary vascular changes after RVAD implantation is needed.

Endovascular treatment for intracranial mycotic aneurysms prior to cardiac surgery.

The management of patients with infective endocarditis complicated by intracranial mycotic aneurysms is controversial. We present the case of a 21-year-old man who suffered from mitral regurgitation with small vegetations due to infective endocarditis. The problem was associated with a ruptured aneurysm on the right anterior cerebral artery and an unruptured aneurysm on the left middle cerebral artery. Endovascular embolization of these aneurysms and subsequent mitral valve repair led to a successful outcome.