Congenital complete atrioventricular block

A new system, the Toxorhynchites-fluorescent antibody (TFA) test in which the larvae of Toxorhynchites splendens mosquitoes were used for the detection of bluetongue virus (BTV) from Culicoides midges, was developed. Twenty-seven pools of Culicoides midges were collected from bluetongue-prone areas of Tamil Nadu by use of the light-trap and suction-trap methods. A suspension of each pool was injected intrathoracically into T. splendens IV instar larvae and inoculated onto Vero cell monolayers. An indirect fluorescent antibody technique and an immunoperoxidase test were used to detect BTV antigen in smears of crushed midges, crushed larval head smears after incubation for 7 d at 28 degrees and cell monolayers showing cytopathic effects 48 h post inoculation. The suspensions were also injected intravenously into embryonated chicken eggs, and the characteristic BTV-induced lesion(s), viz. cherry-red appearance of embryos, were observed after 48 h. Virus was confirmed by a qualitative neutralization test conducted simultaneously in embryonated chicken eggs. A total of seven out of 27 samples (26%) were positive for the presence of BTV antigen in all the diagnostic systems used. Since BTV propagates readily in experimentally infected T. splendens larvae and the BTV antigen can be detected by the fluorescent antibody technique with a sensitivity comparable to that for virus propagated in tissue culture and embryonated eggs, the TFA system can be adopted as a new method for the isolation of BTV from vectors. The advantages of the TFA system are discussed.     

Cerebral ischemic events associated with prolapsing mitral valve

Twelve patients who had no evidence of arteriosclerotic cerebral vascular disease, lacked hypertension or coagulation defect, and had not been receiving contraceptive therapy had recurrent transient cerebral ischemic attacks (TIAs) and partial nonprogressive strokes. All had prolapsing mitral valve proved by angiocardiography. The average age was 38 years, compared with 62 years in a larger series of patients with TIA associated with arteriosclerosis. We propose that the ischemic events are related to emboli emanating from the abnormal mitral valve with or without an associated paroxysmal cardiac arrhythmia.     

Vegetative bacterial endocarditis on the prolapsing mitral valve. Echocardiographic evaluation

Vegetative endocarditis on the prolapsing mitral valve can be diagnosed with an echocardiogram and the response to therapy can be followed with this technique. A dense mass of fuzzy echoes was noted on the prolapsing posterior leaflet of an echocardiogram from a patient with endocarditis. Three months after the initiation of antibiotic therapy, the mass of echoes had disappeared and was replaced by a dense linear echo, suggesting fibrosis of the part of the mitral valve that had been infected previously. Persistence of the echocardiographic evidence of endocarditis, despite negative blood cultures, may indicate persistence of the risk of peripheral embolization.     

The cumulative risks of prolapsing mitral valve. 40 years of follow-up

Prolapsing mitral valve is a common cardiac condition, occurring in approximately 16 million people in the United States alone. Primary prolapsing mitral valve may be familial or nonfamilial and may be associated with myxomatous degeneration of the mitral valve leaflets, such as occurs in Marfan syndrome and other connective tissue disorders. Secondary forms may be associated with such entities as rheumatic fever (especially after commissurotomy) and coronary artery disease (in the presence of ruptured chordae tendineae), and with such congenital conditions as interatrial defect and primary cardiomyopathy with outflow tract obstruction. Prolapsing mitral valve is characterized by late systolic murmur, mid-systolic click, or both. Arrhythmias occur in the form of benign premature atrial contraction, premature nodal contraction, and paroxysmal atrial tachycardia. As the patient ages, atrial flutter and atrial fibrillation tend to develop. In some chronic cases, especially those involving atrial fibrillation, systemic emboli may occur. Rare premature ventricular contractions may be largely benign, whereas more frequent premature ventricular contractions may lead to severe arrhythmic complexes such as ventricular tachycardia or ventricular fibrillation. With advancing age, atrioventricular conduction defects of varying degrees or sick sinus syndrome may necessitate a pacemaker installation. About one quarter of prolapsing mitral valve cases progress, with increasing mitral insufficiency and increasing enlargement of the left atrium and left ventricle, which at times leads to congestive heart failure. Coronary artery disease may occur with the severity commensurate with the patient's age group. About three quarters of patients with prolapsing mitral valve syndrome lead normal lives.     

Predisposing factors of valve regurgitation in complete atrioventricular septal defect

OBJECTIVES: We sought to determine the intrinsic risk factors of valve regurgitation in complete atrioventricular septal defect. BACKGROUND: Progression of regurgitation varies in each case, although the structure of the common atrioventricular valve itself is a predisposing factor. METHODS: In 90 consecutive patients undergoing surgical repair, we evaluated the preoperative and postoperative regurgitation, valve morphology, age at surgery and associated anomalies. A regurgitation jet with a high velocity reaching the deep left atrial wall by echocardiography was estimated as marked regurgitation. RESULTS: None of the 40 patients with Rastelli type C and an undivided inferior bridging leaflet had preoperative regurgitation in the first year of life, and 12% of them (95% confidence intervals [CI]: 0% to 28%) showed regurgitation at the age of 2. Of the remaining 50 with Rastelli type A and/or a divided inferior leaflet, regurgitation was determined in 21% (95% CI: 6% to 35%) of those 1 year old and in 49% (95% CI: 29%7 to 69%) of those 2 years old (p < 0.01). All patients underwent corrective surgery using the double-patch technique, with the "cleft" being sutured adequately. Irrespective of the valve morphology, regurgitation remained in 52% (12 of 23) of those with preoperative regurgitation, whereas regurgitation developed postoperatively in 28% (16 of 58) of those without regurgitation (p < 0.001). CONCLUSIONS: Those with Rastelli type C and an undivided inferior leaflet had a lesser degree of progression of preoperative regurgitation. However, regurgitation was likely to exist even after adequate repair once regurgitation had already advanced. Therefore, early primary repair before progression of the regurgitation may be the key to maintaining better competence of the atrioventricular valve.     

Neonatal lupus syndrome. Association with complete congenital atrioventricular block

Neonatal lupus erythematosus (NLE) is characterized by persistent congenital complete heart block, often without any other structural heart defects. Lupus-like dermatitis is seen transiently, more rarely hepatitis and thrombocytopenia occurs. Recent investigations have shown a close relation between NLE and maternal anti-Ro/La antibodies. These antibodies seem responsible for the destruction of the bundle of His and the AV node in the foetus. Total AV block is seen in 1:15.-22,000 of liveborn children, 70-90% of them are caused by NLE. It is difficult to identify the pregnancies at risk since at delivery most of the mothers (up to 66%) are without symptoms. If the mother has anti-Ro/La antibodies the risk for having a child with NLE is probably less than 5%. However, new investigations have shown that mothers who in addition have anti-DNA antibodies have significantly lower risk of bearing a child with NLE. In most cases foetal complete AV block is found accidentally during pregnancy. Slow foetal heart rate with the demonstration of AV dissociation should not, unless the foetus shows sign of incompensation, lead to acute delivery, but pregnancy should be monitored carefully by serial echocardiography. More than half of the children with congenital heart block need pacemaker therapy shortly after birth. The other children should be followed closely for signs of incompensation and may need pacemaker therapy later on.     

Duration of complete atrioventricular block after congenital heart disease surgery

Children with complete heart block following surgery for congenital heart diseases were prospectively followed to assess the timing for recovery of atrioventricular conduction, and to determine if there were clinical variables that reliably predict permanent heart block. Recovery of atrioventricular conduction occurred by postoperative day 9 in 97% of patients with transient heart block.     

Myxoma of the mitral valve prolapsing into the left atrium and ventricle: report of a case

A rare case of myxoma originating from the mitral valve is reported. A 25-year-old woman was found to have a mobile mass around the mitral valve that prolapsed into the left atrium and the left ventricular outflow tract. The mitral valve was approached via the left atrium and aorta, and was excised completely along with the tumor; it was thus replaced with a mechanical prosthesis. The patient recovered and demonstrated no signs of recurrence 16 months postoperatively.     

Extracorporeal shock wave lithotripsy in a patient with complete atrioventricular heart block

Extracorporeal shock wave lithotripsy using a spark gap generator is contraindicated in patients with complete atrioventricular heart block. A case of a patient with such a heart block, who successfully underwent renal lithotripsy, without cardiac pacemaker, is reported.     

Congenital malformations of the mitral valve in children. Pathology and surgical treatment

A systematic study of congenital mitral valve malformations was undertaken on a surgical basis in an attempt to develop techniques of valvular reconstruction adapted to the various lesions. Forty-seven children between the ages of 4 months and 12 years (average 6 years, 4 months) have been operated upon between January, 1970, and March, 1976. Valvular lesions were classified into four group: Group I, mitral insufficiency owing to valvular lesions: Group II mitral insufficiency with subvalvular lesions; Group III, mitral insufficiency and stenosis; Group IV, stenosis. Associated lesions (ventricular or atrial septal defects, coarctation, or aortic valve stenosis) were present in 31 patients (65 per cent) and were corrected during the same operation. Valve reconsruction was possible in 38 patients whereas valve replacement was necessary in 9 patients. In the valve repair group there were three operative deaths (8 per cent), no late deaths, one reoperation for residual ventricular septal defect, and one myocardial infarction. In the valve replacement group of 9 patients, there were three operative deaths, three late deaths, and one case of repeated embolization. Thirty-one of 38 patients in the valve repair group were classified into Functional Class I after the operation (86 per cent), 2 were in Class II, and one in Class III. Minimal or moderate regurgitation and cardiomegaly persisted in the majority of the patients. Pulmonary artery pressure significantly decreased, however, as demonstrated by postoperative catheterization in 17 patients.     

Single lead atrial synchronous ventricular pacing in Japanese patients with complete atrioventricular block

The purpose of this study was to review our experience with atrial synchronous ventricular pacing devices (THERA VDD pacing systems, Medtronic, Inc., U.S.A.) using single atrioventricular leads in Japanese patients with complete atrioventricular block and normal sinus function. Twenty patients with a mean age of 55 +/- 13 years underwent implantation of VDD pacemakers. At implantation the amplitude of atrial signals in the supine position during normal breathing, which was measured directly using an external pacing system analyzer, ranged from 1.8 to 5.8 mV with a mean amplitude of 3.4 +/- 1.4 mV. Atrial amplitudes did not change during deep breathing (3.3 +/- 1.1 mV) or in the semi-Fowler position (3.4 +/- 1.6 mV). Atrial oversensing or undersensing was not observed in any of the patients. During a follow-up period, the percentage of atrial synchronization was >95% in 19 patients, and none of the patients had pacemaker related tachycardia or pacemaker related complications. These results were promising enough to warrant the extension of the clinical use of the VDD pacemaker.     

Incidence of induced atrial fibrillation/flutter in complete atrioventricular block. A concept of ''atrial-malfunctioning'' atrio-hisian block

Here we report two types of bovine prion protein (PrP) mRNA that possessed different lengths of the 5'-untranslated region and were expressed in various bovine tissues. The two mRNA species were transcribed from identical positions but differed in the usage of the splice site for exon 1/intron. One mRNA possessed exon 1 consisting of 53 nucleotides and the other possessed exon 1 consisting of 168 nucleotides. Usage of exons 2 and 3 was identical for the two mRNA species. The two mRNA species were detected in all but spleen tissue; the mRNA possessing 168-nt exon 1 was not detected in bovine spleen. This is the first report on the tissue-specific alternative splicing of PrPc mRNA in any other species. Only a low level of PrPc appeared to be present in bovine spleen. These results suggested the possibility that the mRNA possessing 53-nt exon 1 was inefficiently translated into Prp; however, in vitro translation analysis showed no marked difference in translational efficiency between the two mRNA species.     

Mitochondrial encephalomyopathy (Kearns-Sayre syndrome) with complete atrioventricular block: a case report

A pacemaker was implanted into a 17-year-old man with cardiac failure due to complete atrioventricular block complicated by mitochondrial encephalomyopathy (Kearns-Sayre syndrome). Due to the possible complication of latent myocardial dysfunction, it was decided to implant the dual chamber pacemaker (DDD) and the operation mode was set to DDD 70 ppm 1 year after implantation; this alleviated the cardiac failure. In this case, the necessity of preventive pacemaker implantation in the early stage of cardiac failure was recognized.