Clinical application of the M-numbers of aortic cannulas during hypothermic cardiopulmonary bypass in pediatric patients

A standardized system to describe the pressure-flow characteristics of a given cannula has recently been proposed and has been termed the M-number system. Using 3 different sizes of aortic cannulas in 50 pediatric cardiac patients on hypothermic cardiopulmonary bypass, we analyzed the correlation between experimentally and clinically derived M-numbers and found it to be positive. Clinical M-numbers were typically 0.35 to 0.55 greater than experimental M-numbers and correlated inversely with a patient's temperature change; this was most probably due to increased blood viscosity arising from hypothermia. This inverse relationship was more marked in higher M-number cannulas. The clinical data obtained in this study suggest that the experimentally derived M-number correlates strongly with the clinical performance of the cannula and that the influence of temperature is significant.     

Long-term results of valve replacement using antibiotic-sterilised homografts in the aortic position

Objective.

Antibiotic-sterilised homograft valves stored at 4 °C have been implanted in the subcoronary position in this unit since 1973. This study was undertaken in order to assess the longterm function of these valves.

Methods.

All 249 patients undergoing homograft aortic valve replacement (AVR) at the Wessex Cardiothoracic Centre between April 1973 and December 1994 were studied. Homograft valve sizes ranged from 15 mm to 28 mm internal diameter, 202 (81.1%) varying between 18 mm and 22 mm. The mean patient follow-up was 12.4 years with a total follow-up of 3096 patient-years. There were six early deaths (2.4%).

Results.

On actuarial analysis, survival was 78.5 ± 2.7% (1SE) at 10 years, 65.7 ± 3.3% at 15 years and 55.0 ± 3.9% at 20 years. The freedom from redo AVR was 87.9 ± 2.4% at 10 years, 71.7 ± 3.8% at 15 years and 49.7 ± 5.6% at 20 years. The freedom from structural degeneration was 85.5 ± 2.5% at 10 years, 63.6 ± 4.0% at 15 years and 41.9 ± 6.4% at 20 years. On multivariate analysis the risk of valve failure was significantly higher in younger patients (P < 0.0001) and in those who underwent aortic root tailoring (P = 0.024). The freedom from endocarditis was 98.4 ± 0.9% at 10 years, 96.2 ± 1.6% at 15 years and 95.1 ± 1.9% at 20 years. Of the 249 patients, 218 had an isolated homograft AVR and were not anticoagulated. In this group there were two possible thromboembolic events.

Conclusion.

As well as the established haemodynamic benefits, this study has shown that homograft AVR with antibiotic-sterilised 4 °C stored homograft valves implanted in the subcoronary position, offers good long-term results.     

Prevalence of cardiac and aortic enlargement in rheumatoid arthritis and its relationship to some characteristics of the patients

Summary The chest radiographs of 309 patients with rheumatoid arthritis (RA) were compared with those of 309 controls matched for sex and age. Cardiac enlargement was more frequent in RA females than in controls (P<0.05) and the frequency of aortic shadow enlargement was higher in RA patients aged 60 years than in controls (P<0.05). Both cardiac and aortic enlargement was significantly related to several parameters of the severity and the activity of RA, corticosteroid therapy, and elevated blood pressure. A high mortality was present in patients with aortic enlargement and in patients with ECG signs of myocardial ischaemia.     

Methyldopa produces central inhibition of parasympathetic activity in the cat

Summary -Methyldopa (10–100 mg/kg i.v.) produced a dose-dependent pupillary dilation in anaesthetized cats which was antagonized by subsequent administration of yohimbine hydrochloride (0.5 mg/kg i.v.). The peak effects were observed approximately 2–3h after injection. This -methyldopa-induced mydriasis was present only when the parasympathetic innervation to the iris was intact. Prior treatment with yohimbine (0.5 mg/kg i.v.) 30 min before -methyldopa also antagonized the mydriatic effect, whereas pretreatment with phenoxybenzamine (2.5 mg/kg i.v.) did not. In contrast, phenoxybenzamine, but not yohimbine, effectively antagonized the pupillary dilation produced by adrenaline (0.3–10.0 g/kg i.v.). These results suggest that -methyldopa produces mydriasis in the cat by means of CNS inhibition of tonic outflow from the oculomotor nucleus and that an -adrenergic inhibitory mechanism may be involved. This conclusion is supported further by experiments in which direct measurements of ciliary nerve activity were made.     

脂质体粒径的分光光度法检测

目的确立分光光度法判断脂质体相对大小,为评估脂质体物理稳定性提供一种简便、快捷的方法。方法以Rayleigh-Gans-Debye理论为基础,固定脂质体膜材的种类、比例及其在溶液中的总量,分别用乙醇注入法和高压乳匀法制备不同粒径的空间稳定脂质体,以电镜法和热力学光散射法测得的粒径作为标准,找出不同方法制得脂质体在436 nm波长处的吸光度A与粒径D的关系。结果单位磷脂浓度的脂质体溶液在436 nm处log(A_436nm/C_p)与脂质体粒径的对数logD呈线性相关(r²≥0.93,n=5)。结论脂质体溶液的吸光度能反映脂质体相对大小,可作为一种评定脂质体物理稳定性的方法。     

Changes in patterns of left ventricular hypertrophy after aortic valve replacement for aortic stenosis and regurgitation with St. Jude Medical cardiac valves

In this study, we analyzed the extent and pattern of regression of left ventricular (LV) hypertrophy after aortic valve replacement in patients with aortic stenosis (AS) and compared the results with those of another group of patients with aortic regurgitation (AR). Seventy patients who underwent isolated aortic valve replacement were divided into 2 groups. Group 1 was comprised of 29 patients who underwent aortic valve replacement for aortic stenosis, and Group 2 of 41 patients who underwent aortic valve replacement for aortic regurgitation. A third group of 10 healthy subjects served as a healthy control group. Echocardiographic studies were done before the operation and 5 years postoperatively. At follow-up, a significant reduction in the left ventricular mass was found in both groups, but it remained significantly greater than in the healthy control group. The ratio of LV wall thickness to radius (th/r) in Group 1 decreased significantly, and at follow-up it was within the normal value. In Group 2, the th/r ratio increased, and at follow-up it was within the normal value. After aortic valve replacement, the wall thickness remained significantly greater than normal for patients with AS, and the chamber radius remained significantly greater than normal for patients with AR. For these reasons, LV hypertrophy still existed in both groups at postoperative follow-up. The actuarial survival rate was 85.3% at 16 years for Group 1 and 83.4% at 18 years for Group 2. There was no significant difference in the long-term survival rates between the 2 groups. Actuarial freedom from valve-related events was 91.9% at 16 years for Group 1 and 82% at 18 years for Group 2. There was no significant difference in the valve-related event free curves between groups. After 5 years of follow-up, th/r reached normal for both groups, indicating remodeling of the LV geometry after aortic valve replacement.     

Assessment of adolescent varicocele

Varicocele is the most important male factor responsible for decreased fertility potential in married couples. From March through June 1994, 2,470 school boys aged 10–20 years were examined to establish the incidence of consecutive grades of varicocele and to develop a protocol for diagnosis and treatment of adolescents with varicocele. Grade 1 varicocele was found in 18%, grade 2 in 12%, and grade 3 in 5% of the population examined. An original protocol of ultrasonographic (US) examination (previously verified by angioscintigraphy) was introduced to assess boys with clinically diagnosed varicocele. The volume of each testis, testicular volume decrease (TVD), pampiniform vein diameter (PVD), and basal (BBF) and maximum blood flow (MBF) velocities were measured in 625 boys. In 74 cases a semen analysis was performed. The statistical analysis revealed that the presence of venous reflux and PVD correlated with the grade of varicocele. Decreases in testicular volume were highly dependent on the grade of varicocele, PVD, and BBF and MBF velocities. Analysis of the relationship between spermatic (boys over 17 years) and US findings revealed that the quality of spermatogenesis can be predicted by US examination in adolescents with varicocele. The authors recommend multiparametric US examination as a reliable, objective, and repeatable technique for establishing criteria for operative treatment in boys under 18 years of age with varicocele as well as for postoperative evaluation.     

Aortic Stenosis and Patent Ductus Arteriosus: Pressure Gradients Pre- and Posttranscatheter Ductal Occlusion

Three patients with patent ductus arteriosus and moderate aortic stenosis had a marked reduction in aortic valve gradient following transcatheter ductal occlusion. The hemodynamic effects of an aortopulmonary shunt on the severity of left ventricular outflow obstruction and the implications on intervention are discussed.     

Surgical Treatment of Aortic Root Aneurysm Related to Marfan Syndrome in Early Childhood

The prognosis of Marfan syndrome in both adult and pediatric patients is primarily related to the cardiovascular complications. In infantile Marfan syndrome, although involvement of the mitral valve is the most frequently encountered cardiovascular lesion, the aortic root can be more worrisome because of its excessive dilatation, leading to aortic insufficiency or dissection. If the role of elective surgery is relatively well defined for adult patients, it is still debated during childhood. We report two patients, aged 22 months and 5 years, each presenting an aortic root aneurysm related to Marfan syndrome, and each treated with the Bentall procedure without specific age-related mortality or morbidity. These two patients experienced normal growth and were free of any complication for a follow-up period of 8 and 2 years, respectively. More than an absolute value of the aortic root dimension, it is the conjunction of the rate of progression of the aortic root dilatation, the degree and the duration of the aortic valve regurgitation, and its resulting left ventricular dysfunction that must be taken into consideration in choosing the surgical option.     

胸主动脉瘤手术体外循环管理

目的总结我院1993年8月至2004年5月29例胸主动脉瘤手术体外循环(CPB)经验。方法29例胸主动脉瘤患者,实施Bentall’s手术、主动脉次全弓及全弓置换术及升或胸降主动脉人工血管置换术。根据术式分别采用常规中低温CPB,中、深低温停循环加选择性脑灌注,选择性脑灌注加下半身灌注、部分股股转流等灌注方法。结果平均CPB时间(179·8±78·1)min。并发症以出血和感染为主。早期死亡2例,晚期死亡4例。死亡率20·7%。结论正确选择CPB方法及良好的CPB管理是胸主动脉瘤手术成功的保障。