Value of a cinefluoroscopic assessment of the Lillehei-Kaster prosthetic heart values

In order to assess the functioning of the pivoting disc of the Lillehei-Kaster prosthetic valve, a cinefluoroscopic technique using multiple angulations was developed. The disc was detected in 240 (99%) of the 242 valves studied (126 aortic, 107 mitral, and nine tricuspid valves). The maximal-opening angle of the disc was measured in 75% of the aortic but only 20% of the mitral valve prostheses in the 182 valve studies in which this was attempted. Prosthetic dysfucntions were suspected clinically in three aortic and three tricuspid valves and confirmed with the cinefluoroscopic technique. This cinefluoroscopic approach constitutes a rapid, noninvasive, and sensitive evalaution of the function of the Lillehei-Kaster prosthetic valve in the aortic position.     

Type C double aortic arch

Four infants with type C double aortic arch (double aortic arch with aberrant left subclavian artery) are discussed. The diagnosis was based on symptoms and signs of tracheoesophageal compression with a bilateral impression in the frontal plane of the esophagogram, as well as on early visualization of the aberrant left subclavian artery during countercurrent right brachial angiography. Division of the atretic segment of the left arch and of the ligamentum arteriosum relieved the symptoms.     

Mirror-image right aortic arch: A proposed mechanism in symptomatic vascular ring

We describe a rare case of right aortic arch with mirror-image branching and a left ductus arteriosus that form an anomalous vascular ring. The unusual feature of this symptomatic vascular ring is presence of a left (posterior) circumflex descending aorta in lieu of an aortic diverticulum which usually represents the posterior element of the vascular ring associated with right aortic arch and mirror-image branching. This we believe is the seventh reported case of Type 1 right aortic arch and only the third such case with a left circumflex descending aorta. Accurate diagnosis was made by barium esophagogram and angiocardiogram and was confirmed surgically. We propose a new theory as to why some vascular rings formed by the right aortic arch are symptomatic while others are not.     

ARTERIAL ANOMALIES CAUSING COMPRESSION OF THE TRACHEA AND/OR THE OESOPHAGUS

The experiences of diagnosis and treatment of arterial anomalies causing compression of the trachea and/or the oesophagus in 30 symptomatic cases are reported. The main diagnostic aid is the radiological examination of the chest in the anterior-posterior and lateral projection including adequate contrast filling of the oesophagus. This investigation, using water-soluble contrast media, should be performed in infants with stridor and other respiratory difficulties and in dysphagia. With improved surgical technique and postoperative care the operative risk of today is low and surgery should be seriously considered in symptomatic cases. Operation may be necessary as an emergency treatment.     

Right-sided cervical aortic arch associated with tetralogy of Fallot and peculiar tortuosity of the descending aorta

A right-sided cervical aortic arch, tetralogy of Fallot, and a peculiar tortuosity of the descending aorta in which the aorta formed triple loops were diagnosed by angiocardiography in a 12-year-old girl. Histologic examination of the biopsied wall of the left subclavian artery, taken at the time of a Blalock-Taussig anastomosis, revealed no elastic-tissue defect.     

Effects of clonidine on baroreceptor function in anesthetized dogs

The effects of clonidine (15–30 μg/kg i.v.) on carotid sinus and other baroreceptors were investigated in anesthetized dogs. In 14 control dogs, right carotid sinus pressure was controlled by retrograde perfusion through the common carotid artery at constant flow with femoral arterial blood. Graded reductions in heart rate and blood pressure induced by graded increases in carotid sinus pressure were prevented, whereas reflex bradycardias associated with norepinephrine pressor activity were potentiated by clonidine. Norepinephrine-induced bradycardia, although reduced, still persisted after chronic bilateral sinusectomy and these responses were also potentiated by clonidine. In contrast, clonidine did not potentiate reflex bradycardia in dogs 20 days after aortic stripping. In intact dogs, clonidine inhibited the response to bilateral carotid artery occlusion and to carotid sinus nerve stimulation. These studies suggest that clonidine can inhibit carotid sinus baroreceptor function and simultaneously potentiate other, presumably aortic, baroreceptor activity.     

Estimation of reynolds shear stresses during pulsatile flow in the region of aortic valves

Some investigators have attempted to estimate the Reynolds shear stress on the basis of a single component of velocity. The purpose of this investigation is to determine the validity of such estimates in a complex flow field, such as occurs in the cardiovascular system in the region of the aortic valve. Turbulent velocities were obtained in an in vitro pulse duplicating system with a two-channel laser Doppler anemometer. Velocities were measured in the region of two stenotic natural aortic valves and a normal stent mounted porcine bioprosthetic valve. Constants of proportionality between the Reynolds shear stress, averaged over ejection, and the Reynolds normal stress were determined. The constants of proportionality depended uppn the local conditions, namely, whether the valves were stenotic or normal bioprosthetic. There was wide scatter of data. This suggests that any estimate of the Reynolds shear stress, based upon a single axial velocity in a complex flow field, such as occurs in the cardiovascular system, is likely to be inaccurate.     

胎儿牙弓的形态与测量研究

目的 观察胎儿期牙胚在颌骨内的排列情况及牙弓长度的发展进行规律。方法 应用牙连同颌组织连续切片技术，对４０例不同胎龄胎儿的上下颌骨作水平方面切片，观测并统计。结果 胎儿２８周后牙胚拥挤，上牙弓拥挤更显著；上牙弓发育较早，但下牙弓发育速度快于上牙弓。结论 胎儿期牙列拥挤明显，下牙弓长度主要在胎儿期已基本完成。     

Hemiarthroplasty in rotator cuff tear arthropathy

Rotator cuff tear arthropathy results in a painful glenohumeral joint with poor function. Loss of the stabilizing effect of the rotator cuff allows superior subluxation of the humeral head. The poor mechanical advantage of the deltoid muscle creates a weak, poorly functioning shoulder. Hemiarthroplasty with a large humeral head component can relieve pain and retain some of the mechanical advantage of the deltoid by lateralizing the center of rotation of the humeral head and regaining deltoid length. A larger-than-anatomic humeral head decreases the risk of further superior subluxation of the humeral head by decreasing wear. Stability is regained by retensioning the deltoid muscle envelope. This article reviews the technique of large head hemiarthroplasty in this difficult reconstructive problem.     

Endoluminal stent graft repair for acute and chronic type B aortic dissection and atherosclerotic aneurysm of the thoracic aorta: an interdisciplinary task

Objective: Endoluminal thoracic aortic stenting is a new therapeutic tool in reducing the operative trauma of the patient. However, the inherent risks of aortic stent grafting are perivascular leakage, stent dislocation, blunt rupture of the aorta, side branch occlusion and neurological sequelae. To reduce these risks, in our institution all stent implantations were performed in close collaboration with our fellow cardiologists under biplane X-ray control supported by simultaneous intravascular and transoesophageal ultrasound imaging. Methods: Between August 1999 and August 2001, endovascular stent graft repair was performed in 34 patients (27 male, seven female) with a mean age of 68.6±7 years (range 58–84). Indication for treatment was an acute Type B aortic dissection in six patients (18%), a symptomatic chronic Type B dissection in 12 patients (35%), a true aneurysm of the descending aorta in seven patients (21%) and an atherosclerotic contained rupture of the descending aorta in nine (26%) patients. Out of six acute type B dissections three patients (8.8%) and one patient (2.9%) out of the chronic dissection group were in severe haemorrhagic shock, ventilated and required high-dose adrenergic support. The others (30 patients, 88.3%) remained symptomatic despite maximum medical treatment. In a special case a combined surgical and endoluminal stent graft repair was performed. Individually manufactured Talent, Medtronic AVE (33), and Gore (1) stents were used. Follow-up examination was performed 1 week after implantation and repeated every 3 months (mean follow-up 8 months, range 1–24). Results: In all patients the aneurysm or the entry of the dissection could be excluded. The observed hospital mortality was 2.9% (one patient). No perivascular leakage, no stent dislocation, no neurological deficit or perfusion impairment was observed. All patients except four were extubated immediately after the procedure and discharged from hospital on postoperative day 2–3. The late procedure-related mortality was 5.8% (two patients) resulting in an overall mortality of 8.8% (three patients). Conclusion: Stent graft repair is a safe and feasible treatment option for selected patients, especially in emergency situations, if the aortic lesions can be clearly identified and localized. The use of biplane X-ray control combined with simultaneous intravascular and transoesophageal ultrasound imaging in an interdisciplinary approach enables a more precise targeting of the stent landing zone, resulting in low morbidity and mortality rates.