Transesophageal Programmed Atrial Pacing as a Method of Selecting Patients with Sick Sinus Syndrome for Permanent Atrial Pacing

Many recent studies have shown transesophageal programmed atrial pacing (TP) as a very practical, safe and convenient way for assessment of sinus node function and AV conduction. On the other hand, permanent atrial pacing is known to be superior to ventricular pacing due to arrhythmogenic and hemodynamic reasons. This is the reason why we decided to use TP as a method of choosing patients with sick sinus syndrome (SSS) for permanent atrial pacing. Sixty-three patients with symptomatic (58) and asymptomatic (5) SSS in a variety of clinical situations were examined in this way. The following electrophysiological features were examined: sinus cycle length, sinus node recovery time as well as corrected time, secondary pause after overdrive stimulation, sinoatrial conduction time, Wenckebach point, induction of supraventricular arrhythmias by S1, S2, S3 programmed stimulation and burst pacing. Patients with abnormal parameters were examined once more after intravenous atropine 0.2 mg/kg to evaluate parasympathetic component. Standard 12-lead ECG was performed in ail, and Holter monitoring in most of patients.
Twenty-six patients were candidates for permanent AAI pacing. Failures occurred in eight patients usually due to low P wave amplitude and electrode instability. Eighteen patients received AAI pacing systems: eight with brady-tachycardia syndrome, nine with brady-arrhythmia and one with sinoatrial block. In the follow-up of 5–28 months in one patient occurred high degree AV block (11°) during digitalis therapy. Reduction of doses made this block disappear. Examination of Wenckebach point and possibility of inducation of supraventricular lachyarrhythmias in cases of atrial overexcitability are particularly useful in selecting patients for AAI pacing. (PACE, Vol 11 November Part II 1988)     

Development and maturation of the fibrous components of the arterial roots in the mouse heart

The arterial roots are important transitional regions of the heart, connecting the intrapericardial components of the aortic and pulmonary trunks with their ventricular outlets. They house the arterial (semilunar) valves and, in the case of the aorta, are the points of coronary arterial attachment. Moreover, because of the semilunar attachments of the valve leaflets, the arterial roots span the anatomic ventriculo‐arterial junction. By virtue of this arrangement, the interleaflet triangles, despite being fibrous, are found on the ventricular aspect of the root and located within the left ventricular cavity. Malformations and diseases of the aortic root are common and serious. Despite the mouse being the animal model of choice for studying cardiac development, few studies have examined the structure of their arterial roots. As a consequence, our understanding of their formation and maturation is incomplete. We set out to clarify the anatomical and histological features of the mouse arterial roots, particularly focusing on their walls and the points of attachment of the valve leaflets. We then sought to determine the embryonic lineage relationships between these tissues, as a forerunner to understanding how they form and mature over time. Using histological stains and immunohistochemistry, we show that the walls of the mouse arterial roots show a gradual transition, with smooth muscle cells (SMC) forming the bulk of wall at the most distal points of attachments of the valve leaflets, while being entirely fibrous at their base. Although the interleaflet triangles lie within the ventricular chambers, we show that they are histologically indistinguishable from the arterial sinus walls until the end of gestation. Differences become apparent after birth, and are only completed by postnatal day 21. Using Cre‐lox‐based lineage tracing technology to label progenitor populations, we show that the SMC and fibrous tissue within the walls of the mature arterial roots share a common origin from the second heart field (SHF) and exclude trans‐differentiation of myocardium as a source for the interleaflet triangle fibrous tissues. Moreover, we show that the attachment points of the leaflets to the walls, like the leaflets themselves, are derived from the outflow cushions, having contributions from both SHF‐derived endothelial cells and neural crest cells. Our data thus show that the arterial roots in the mouse heart are similar to the features described in the human heart. They provide a framework for understanding complex lesions and diseases affecting the aortic root.     

Assessment of VVI Diagnostic Pacing Mode in Patients with Cardioinhibitory Carotid Sinus Syndrome

In this study, we used Holter pacemakers in a group of 13 patients affected by severe carotid sinus syndrome in order to evaluate its evolution. All the patients had one to three syncopal episodes and frequent other symptoms such as fainting, dizziness, lightheadedness and pre-syncope interferring with their daily activity so that pacemaker therapy was considered necessary. Patient selection criteria were: presence of the isolated cardioinhibitory type, absence of associated sinus dysfunction and absence of symptomatic WI pacemaker effect. All the patients received a Micropacer 1 device; among special functions, bradycardia events counter was activated and programmed so that each sequence of three consecutives beats at a cycle length 1.5 sec (i.e., 4.5 sec total interval) could he recognized and stored in its memory. The follow-up lasted 13±7 months. Brady events occurred in eight out of 13 patients (62%), during this period. Syncope and major symptoms disappeared in ail the patients; mild dizziness recurred rarely in two patients and were not linked to brady-events recording. In conclusion, disappearance of severe symptoms observed after pacemaker implant in cardioinhibitory carotid sinus syndrome seems to depend from pacing therapy, in most cases, yet from the benign natural course of the disease in some other cases.     

Adequacy of Pacing Rate During Exercise in Rate Responsive Ventricular Pacing

Our objective was to determint; the adequate pacing rate during exercise in ventricular pacing by measuring exercise capacity, cardiac output, and sinus node activity. Eighteen patients with complete AV block and an implanted pacemaker underwent cardiopulmonary exercise tests under three randomized pacing rates: fixed rate pacing (VVJ) at 60 beats/min and ventricular rate-responsive pacing (VVIR) programmed to attain a heart rate of about 110 beats/min ar 130 beats/min (VVIR 110 and VVIR 130, respectively) at the end of exercise. Compared with VVI and VVIR 130, VVIR 110 was associated with an increased peak oxygen uptake(VVIR 110:20.3 ± 4.5 vs VVI: 16.9 ± 3.1; P < 0.01; and VVIR 130: 19.0 ± 4.1 mL/min per kg, respectively; P < 0.05) and a higher oxygen uptake at anaerobic threshold (15.3 ± 2.7, 12.7 ± 1.9; P < 0.01, and 14.6 ± 2.6 mL/min per kg; P < 0.05). The atrial rate during exercise expressed as a percentage of the expected maximal heart rate was lower in VVIR 110 than in VVI or VVIR 130 (VVIR 110: 75.9%± 14.6% vs VVI: 90.6%± 12.8%; P < 0.01; VVIR 110 vs VVIR 130: 89.1%± 23.1%; P < 0.05). There was no significant difference in cardiac output at peak exercise between VVIR 110 and VVIR 130. We conclude that a pacing rate for submaximal exercise of 110 beats/min may be preferable to that of 130 beats/min in respect to exercise capacity and sympathetic nerve activity.     

小儿睾丸卵黄囊瘤误诊分析

目的　减少小儿睾丸卵黄囊瘤的误诊。方法　回顾一组 2 8例小儿睾丸卵黄囊瘤病例 ,分析其误诊情况。结果　 1 9例曾误诊为睾丸炎、鞘膜积液、腹股沟斜疝、睾丸附睾结核等疾病 ,部分病例行睾丸肿块穿刺及按鞘膜积液行手术治疗。结论　为减少误诊必须提高对小儿睾丸卵黄囊瘤的认识 ,细致的体格检查 ,血清甲胎蛋白 (AFP)测定和超声检查对诊断有重要价值 ,但不可仅依据透光实验和 AFP结果就排除本病 ,必要时可手术探查 ;对睾丸肿块未排除肿瘤者不宜行诊断性穿刺     

产后上矢状窦血栓形成12例报告及其预防措施的探讨

目的：探讨产后上矢状窦血栓形成的发病机制、诱发因素及预防发病的措施。方法：回顾12例产后上矢状窦血栓形成患者临床资料，特别是围产期并发症、合并症、分娩方式及产后生活起居等，分析诸因素与上矢状窦血栓形成的可能关系。结果：产褥期凝血机能增强，并发妊娠高血压综合征，产时、产后失血过多，产后多汗、不正确发汗，产后卧床较久、饮水不足、高脂饮食，产褥感染及剖宫产等是产后上矢状窦血栓形成的诱发因素。结论：注意围产期相关并发症、合并症的防治、严格剖宫产指征，避免盲目剖宫产及普及产褥期卫生知识，避免产后卧床较久、合理饮食，可减少产后上矢状窦血栓形成的发生。     

Behcet's Disease: Presentation With Sagittal Sinus Thrombosis Diagnosed Noninvasively

The standard evaluation of patients with intracranial hypertension frequently does not reveal a discrete pathophysiologic process, leading in these cases to classification of the syndrome as "benign." We present a 35-year-old woman with a recent diagnosis of pseudotumor cerebri who presented with headache, emesis, and blurring of vision. Her symptoms were progressive despite two lumbar punctures that revealed normal cerebrospinal fluid under high pressure. Contrast and noncontrast CT scans were normal; both the cerebrospinal fluid and CT neuroimaging were thus consistent with benign intracranial hypertension. An MRI, however, supported the presence of sagittal sinus thrombosis, a finding which was confirmed by MR venography. Further workup for an underlying cause of sinus thrombosis disclosed symptoms and signs fulfilling the diagnostic criteria for Behcet's disease. Cerebral venous (or sinus) thrombosis should be considered in the differential diagnosis of intracranial hypertension. Behcet's disease, while extremely rare, should be considered as a potential cause of cerebral venous thrombosis. Magnetic resonance venography can serve as a useful diagnostic study in situations where confirmation or exclusion of sinus thrombosis is required.     

鼻内镜下经上颌窦前壁上颌窦囊肿摘除术

目的 探讨鼻内镜治疗上颌寞囊肿的手术方法。方法 30例单纯性上颌窭囊肿病人，20例行上颌寞前壁进路鼻内镜手术，观察上颌寞各壁，摘除囊肿。5例患者行经上颌窭口鼻内镜下囊肿摘除术，5例患者行下鼻道开窗鼻内镜下囊肿摘除术。结果 行上颌窦前壁进路鼻内镜手术的20例患者，随访6～12个月无复发，无面部不适。结论 该术式操作方便，效果好，不良反应少。     

Rate Hysteresis Pacing: How Valuable Is It? A Comparison of the Stimulation Rates of 70 and 50 Beats per Minute and Rate Hysteresis in Patients with Sinus Node Disease

The main disadvantages of VVI pacing are absence of acceleration of the heart rate and loss of atrial synchronization. The alternatives to AAI and DDD pacing are stimulation at a low rate or hysteresis in order to decrease pacing time and thus reduce AV asynchrony. Nine patients who suffered from sinus node disease and who had been given a multiprogrammable pacemaker were monitored at each of three stimulation rates: 70, 50, and 70 bpm with an inhibition rate of 50 bpm (hysteresis).
The total pacing time was shortest (p < 0.05) for the stimulation rate of 50 bpm as compared to 70 bpm and hysteresis. It was also shorter for the hysteresis mode than for the 70 bpm mode (p < 0.05).
Only for hysteresis pacing was there a significant reduction in the number of changes from conducted cardiac rhythm to pacemaker-induced rhythm. Most patients found the 50 bpm mode preferable. None favored the hysteresis mode.
In patients with sinus node disease and intermittent bradycardia being permanently paced, the periods of AV-conducted rhythm may be lengthened by reducing the stimulation rate from 70 bpm, with or without hysteresis pacing, to 50 bpm. In paced patients with sinus node disease and symptoms due to AV asynchrony, it might be worth trying a decrease in the stimulation rate before resorting to other pacemaker systems.