Evaluating Auditory Pathway by Electrical Auditory Middle Latency Response and Postoperative Hearing Rehabilitation

ABSTRACT

Objective: To establish an effective detection method to evaluate auditory pathway in patients by electrical evoked middle latency response (EMLR) before artificial cochlear implantation, and to analyze the relationship between postoperative hearing rehabilitation and auditory cortex functions. Methods: Twenty-three patients with artificial cochlear implant were recruited. EMLR was measured after adjusting the depth of anesthesia. The electrical auditory brainstem response (EABR) mode with monopolar stimulation and two-phase alternating current square waves was selected. The parameters of EMLR waveforms were recorded by the EABR measurement system. Nerve response telemetry (NRT) was examined by measuring threshold level (T value) and comfortable level (C value) 1 month after power-on, and hearing and speech development was followed up 12 months later.Results: The detection rate of EMLR was 95.65%. The waveforms of EMLR were comparable to those of auditory middle latency response (AMLR), showing decreased latency and interval but similar amplitude. The induction rate of NRT was 69.23%, which was much lower than that of EMLR. The EMLR thresholds were significantly correlated to the T and C values, and were comparable to the T values numerically. The Spearman's r value between EMLR waveforms and CAP scores after using the cochlear implant for 12 months was 0.673 (P < 0.01). Conclusion: An effective detection method to measure EMLR before artificial cochlear implant was established. The thresholds of EMLR were lower than those of NRT. The method can be useful for objective evaluation of auditory cortex functions and postoperative hearing rehabilitation.     

Preliminary Results with an Apico-Aortic Valved Conduit (AAVC) Using Polyurethane and Aortic Allograft Valves

Stenosis of the left ventricular outflow tract is one of the most frequent congenital cardiac anomalies in dogs. The subvalvular stenosis is described as a ring of fibrous tissue located in the left ventricular outflow tract immediately below the aortic valve. The best method of surgical treatment in dogs seems to be relief of the aortic obstruction with a ventricular aortic prosthesis. A new trileaflet valve manufactured out of polyurethane has been developed. For the conduit a woven Dacron graft has been used. In 5 male dogs a valved conduit was implanted between the apex of the left ventricle and the aorta thoracica without using hypothermia and/or cardiopulmonary bypass. Four dogs survived the surgical procedure and showed no clinical symptoms postoperatively. Blood flow through the conduit was demonstrated postoperatively by angiocardiography for a maximum of 22 days, the longest surviving time being 8 weeks. Trials for the replacement of the artificial valve in the conduit by a canine aortic allograft valve are in progress. Studies were done with the cryopreservation of fresh aortic valves. Sterilization, cryoconservation, and storage methods for the allograft are described     

Atrial Septal Defect in Adults: Thirty-eight-year Follow-up of a Surgically and a Conservatively Managed Group

This report describes the long-term (up to 38 years) outcome, in terms of mortality and cardiovascular morbidity, in a non-randomized clinical observation study of a surgically and a conservatively managed group of adult patients with shunt lesions at atrial level. Haemodynamic status was assessed at baseline and at repeat examination. Twelve patients underwent surgical repair of the lesion between these two heart catheterizations, resulting in a marked reduction in heart size and right ventricular systolic pressure. These changes were associated with improvement in functional class and a trend towards less risk of cerebrovascular incidents, but not atrial fibrillation, during follow-up. Among 12 patients not operated on between catheterizations, symptomatic deterioration was common, often necessitating later surgical repair. The results support the assumption that early surgery should be recommended for adults with a haemodynamically significant lesion, to reduce the risk of mortality and prevent symptomatic deterioration.     

Coronary bypass graft patency cannot be determined by multidetector spiral computed tomography

Objectives. Angiography by selective catheterization is the reference standard for coronary bypass graft patency assessment but carries a risk of serious complications. We have investigated whether 16-slice multidetector spiral computed tomography (MDCT) can substitute for selective angiography. Design. Two to three years after coronary artery bypass grafting, 45 patients with a total of 156 bypasses (100 single and 28 sequential grafts) were examined with both MDCT and conventional selective angiography on the same day. The bypasses were classified as patent, stenotic or occluded. Results. The likelihood ratio for MDCT-detected occlusion was 40, reflecting a fairly high combined sensitivity and specificity. However, 24% of the distal anastomoses could not be evaluated by MDCT, mainly because of respiratory movements, artifacts due to metal clips, and small vessel dimensions. Moreover, seven out of 117 bypasses (6%) deemed evaluable by MDCT were wrongly classified by this method. Conclusions. At present, 16-slice MDCT cannot replace selective angiography for assessment of coronary bypass graft patency since 24% of bypasses could not be evaluated by this method, and an error rate of 6% is unacceptable.     

Pericardial Mesothelioma Presented as Constrictive Pericardial Disease

The aim of this report is to present a case of malignant mesothelioma of the pericardium and to illustrate points in diagnosis and treatment of this extremely rare disease. On admission to hospital there were signs of cardiac tamponade, which responded to peri-cardial drainage. The patient subsequently deteriorated and signs of constrictive pericarditis were demonstrated by right heart catheterization and angiography. Surgery was undertaken, but the patient died three hours after pericardectomy due to cardiac failure and multiple thromboembolism.

Pericardial mesotheliomas are rare, as are all primary tumours of the heart. The disease is seldom diagnosed antemortem. The aim of this report is to present one further case and discuss points in diagnosis and treatment.     

Factors influencing late allograft valve failure

Allograft valves are a valuable valve replacement substitute in the surgical management of heart valve disease. It remains the valve substitute of choice in the reconstruction of the right ventricular outflow tract in children with congenital heart disease and in the Ross procedure. However, its durability remains suboptimal, particularly in children. This article reviews the mechanisms and factors implicated in late allograft dysfunction, with a focus on the evidence for an immunological cause for allograft failure. Unravelling the mechanisms of allograft valve failure may allow modification of the allograft to improve its long‐term durability.     

Immediate loading of mandibular overdentures supported by unsplinted direct laser metal-forming implants: results from a 1-year prospective study

Background: At present, only some studies have dealt with immediate loading of unsplinted implants supporting mandibular overdentures. The aim of this prospective study is to evaluate treatment outcomes of mandibular overdentures supported by four one‐piece, unsplinted, immediately loaded, direct laser metal‐forming (DLMF) implants by assessing implant survival rate, implant success, marginal bone loss, and prosthetic complications. Methods: A total of 96 one‐piece DLMF implants were inserted in the edentulous mandible of 24 patients. Four implants were placed in each edentulous mandible. Immediately after implant placement, a mandibular overdenture was connected to the implants. At 1‐year follow‐up, clinical, radiographic, and prosthetic parameters were assessed. Success criteria included absence of pain, suppuration, and implant mobility; absence of continuous peri‐implant radiolucency; and distance between the implant shoulder and the first visible bone contact <1.5 mm. Results: After a 1‐year loading time, the overall implant survival rate was 98.9%, with only one implant lost. Among the surviving 95 implants, two did not fulfill the success criteria; therefore, the implant success rate was 97.8%. The mean distance between the implant shoulder and the first visible bone contact was 0.28 ± 0.30 mm (95% confidence interval, 0.24 to 0.32). Some prosthetic complications were reported. Conclusion: Based on the present results and within the limits of this study, the immediate loading of four unsplinted DLMF implants by means of ball attachment–supported mandibular overdentures seems to represent a safe and successful procedure.