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An infant with nonfamilial hyperekplexia had multiple episodes of tonic spasms that mimicked tonic seizures. They were accompanied by complete heart block and apnea. These episodes did not correlate with electroencephalographic epileptiform changes and were partially responsive to clonazepam, valproic acid, and cardiac pacemaker. Sudden death in hyperekplexia may be related to complete heart block and apnea during seizurelike episodes.
Thyroid storm is a difficult diagnosis in "apathetic" variant of hyperthyroidism. The clinical features may not be evident. Abnormal atrioventricular (AV) conduction, such as complete heart block, in thyrotoxicosis is uncommon. We report a case of a 16-year-old girl presenting with fever, jaundice, heart failure and complete heart block in whom the diagnosis of thyroid storm was initially missed because of the unusual presenting features. Prompt resolution of the conduction abnormality occurred when treatment with carbimazole, intravenous iodide and dexamethasone was instituted.
A case of a 48-year-old woman with frequent syncopal episodes is reported. The electrocardiogram showed high degree AV block with narrow QRS complexes. The His bundle electrogram displayed a split His deflection indicating impairment of conduction within the His bundle of the Mobitz II type. The AH interval was prolonged and Wenckebach phenomenon occurred at the same atrial pacing rate before and after atropine administration. During spontaneous or induced high grade AV block an escape rhythm originating in the distal His bundle was observed. A secondary study performed one year later showed progression to complete AV block. Both His potentials were present, one following the atrial and the other preceding the ventricular deflection. The H'V interval was prolonged and a further lengthening was seen after ajmaline. All these findings indicated proximal, mid, and distal disease of the His trunk.
The expression of calreticulin, a Ca(2+)-binding chaperone of the endoplasmic reticulum, is elevated in the embryonic heart, and because of impaired cardiac development, knockout of the Calreticulin gene is lethal during embryogenesis. The elevated expression is downregulated after birth. Here we have investigated the physiological consequences of continued high expression of calreticulin in the postnatal heart, by producing transgenic mice that overexpress the protein in the heart. These transgenic animals exhibit decreased systolic function and inward I(Ca,L), low levels of connexin43 and connexin40, sinus bradycardia, and prolonged atrioventricular (AV) node conduction followed by complete heart block and sudden death. We conclude that postnatal downregulation of calreticulin is essential in the development of the cardiac conductive system, in particular in the sinus and AV nodes, when an inward Ca(2+) current is required for activation. This work identifies a novel pathway of events, leading to complete heart block and sudden cardiac death, which involves high expression of calreticulin in the heart.
A young primigravida presented at 36 weeks of gestation with complete heart block and triplet pregnancy. She underwent a lower segment cesarean section, and was managed successfully. The patient remained asymptomatic and did not require antiarrhythmic drugs or pacing.
Prenalterol is a new beta-adrenergic agonist which stimulates mainly beta 1-receptors, in contrast to isoprenaline which stimulates both beta 1- and beta 2-receptors. We studied the hemodynamic effects of prenalterol and isoprenaline in seven patients with complete heart block and idioventricular escape rhythm due to ischemic heart disease. Isoprenaline was given as a continuous infusion at two increasing doses (1.7 micrograms/min and 3.4 micrograms/min each given for 30 min). After the second dose of isoprenaline the cardiac index was increased from 2.27 +/- 0.06 to 3.61 +/- 0.60 1/min/m2, heart rate was increased from 34.1 +/- 1.2 to 50.4 +/- 3.1 beats/min and mean blood pressure was decreased by 12.4 mm Hg. Mean pulmonary artery pressure was increased by 2 mm Hg. Prenalterol was given as two i.v. bolus injections of 3.5 mg and 7.0 mg at 15-min intervals. The first dose of prenalterol increased the cardiac index from 2.22 +/- 0.10 to 2.42 +/- 0.12 and heart rate from 37.0 +/- 1.8 to 40.1 +/- 1.7. Mean blood pressure and mean pulmonary artery pressure were unchanged. The second dose of prenalterol did not change the hemodynamic variables significantly compared to the changes after the first dose. We conclude that isoprenaline is preferable to prenalterol for treatment of complete heart block.
The appearance and gradual progression of atrioventricular (A-V) block in the presence of the Wolff-Parkinson-White (WPW) syndrome is an intriguing phenomenon. The vast majority of the reports up to date describe persistence of preexcitation in the face of partial or complete heart block. We describe a patient with severe coronary artery disease, in whom WPW disappeared suddenly, transiently at first, during coronary bypass surgery, and then permanently, probably as a result of an acute myocardial infarction, and in whom all the sinus beats during relentlessly progressive heart block were conducted through the normal A-V conduction system only.
Between January 1, 1980, and March 1, 1986, congenital complete heart block (CCHB) was diagnosed in 11 fetuses utilizing 2-dimensional and M-mode fetal echocardiography. Four of the eleven cases (36.4%) had otherwise structurally normal hearts; 3 survived the perinatal and neonatal period and 1 patient died at 22 days of age. All mothers in this group had systemic lupus erythematosus. Seven of the eleven fetuses (63.6%) presented with CCHB and associated cardiac malformations. All patients in this group died either in utero or shortly after birth. The discovery of CCHB with associated structural malformations of the heart carries an ominous prognosis for fetal and neonatal survival. The diagnosis of CCHB without associated cardiac malformations carries a more favorable outlook. Accurate prenatal diagnosis of CCHB and underlying cardiac status facilitates parental counseling and patient management planning.
Evaluation of fetal bradycardia noted during a routine prenatal visit at 24 weeks' gestation in a mother without symptoms showed an antibody-mediated heart block with anti-La (SSB) antibody present. The fetus had a pericardial effusion and ascites. After maternal steroid therapy, the ascites resolved and the pericardial effusion was substantially diminished. Steroid therapy may be a helpful adjunct for treatment of a premature infant with hydrops as a result of antibody-mediated heart block.
Blunt chest trauma, if sustained selectively to the midchest or precordium, can result in a variety of cardiac injuries (3, 7). These lesions may involve separately or together all structures of the heart, including pericardium, myocardium, valves, and coronary arteries. Depending on the extent of trauma, such injuries can cause varying amounts of mechanical or electrical dysfunction. The incidence and nature of cardiac dysrhythmias following trauma are largely unknown clinically, but have been extensively documented in several animal studies (2, 4, 5). Disturbances in both impulse generation and transmission were noted, usually beginning immediately after impact with the development of complete heart block and progressing quickly through several other electrical patterns to either sinus rhythm or ventricular fibrillation. High-grade atrioventricular (A-V) block has rarely been recognized clinically in association with nonpenetrating heart trauma (1), perhaps because of its rapid replacement by other dysrhythmias. It was, therefore, of interest when a patient presented to this institution in third-degree heart block following a blunt chest injury. Specifics of her illness are discussed.
We present the case of a neonate undergoing surgery on the first day of life for the installation of a permanent pacemaker because of the existence of congenital complete heart block (CCHB) with a basal heart rate of 43 b.min(-1) and minimal elevation after initiating an isoproterenol perfusion. The intervention was under general anaesthesia with laryngeal mask airway (LMA) and spontaneous ventilation. The principal anaesthetic goals were to assure adequate anaesthesia, with haemodynamic and respiratory stability, to maintain the best possible heart rate and to avoid postoperative respiratory depression or apnoea.
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OBJECTIVE: Clinical evidence and experimental evidence suggest that anti-Ro/La autoantibodies are necessary but not sufficient for the development of congenital complete heart block (CCHB). Maternal, fetal, and environmental factors may also contribute to heart damage in CCHB. The aim of our study was to investigate polymorphisms of transforming growth factor beta1 (TGFbeta1) and tumor necrosis factor alpha (TNFalpha) genes in twins and triplets discordant for CCHB whose mothers are anti-Ro/La positive. METHODS: We studied 2 families in which 1 of the mothers gave birth to triplets and the other gave birth to twins. Only 1 child in each family was affected by CCHB, although 1 of the triplets had incomplete heart block. We analyzed TNFalpha and TGFbeta1 polymorphisms in the 2 babies with CCHB and their siblings. TNFalpha polymorphisms at the promoter region and TGFbeta1 polymorphisms at codons 10 and 25 were determined using polymerase chain reaction-restriction fragment length polymorphism analysis. In addition, the production of TGFbeta1 and TNFalpha by resting or mitogen-stimulated peripheral blood mononuclear cells in cell culture supernatants was evaluated by enzyme-linked immunosorbent assay. RESULTS: The profibrotic TGFbeta1 genotype was detected in the twin with CCHB but not in the healthy twin, while all of the triplets displayed the same TGFbeta1 genotype at codon 10. Peripheral blood mononuclear cells from the children with CCHB displayed higher spontaneous and mitogen-stimulated TGFbeta1 secretion than was observed in their siblings. No differences regarding TNFalpha polymorphisms and secretion of TNFalpha were observed. CONCLUSION: The results of this study suggest that, besides anti-Ro/La autoantibodies, a fetal profibrotic response might contribute to the development of CCHB, but additional pathogenic mechanism(s) are also likely to play a role.
OBJECTIVES: The purpose of this paper is to examine the incidence and determinants of permanent complete heart block (CHB) after nonsurgical septal reduction therapy (NSRT), and to evaluate the clinical impact of permanent pacemaker (PPM) placement. BACKGROUND: Nonsurgical septal reduction therapy with ethanol improves the clinical and hemodynamic parameters in patients with symptomatic hypertrophic obstructive cardiomyopathy. Complete heart block is a common complication after NSRT. METHODS: The database of 261 consecutive patients who underwent NSRT at Baylor College of Medicine was reviewed. Clinical variables that were considered as possible determinants for CHB after NSRT were: age, gender, New York Heart Association (NYHA) functional class, left ventricular outflow tract (LVOT) gradient at rest or with provocation, septal thickness, and baseline exercise duration. For electrocardiographic (ECG) variables, the presence of first-degree atrioventricular (AV) block, bifascicular block, left bundle branch block, atrial fibrillation, and left ventricular hypertrophy were analyzed. In addition, the volume of ethanol injected, the method of administration of ethanol (i.e., bolus vs. slow injection [over 30 to 60 s]), number of septal arteries occluded, use of myocardial echocardiography, and infarct size as determined by peak creatine kinase level. RESULTS: Of 261 consecutive patients, 37 had PPM or automatic implantable cardiac defibrillator placed before NSRT. Of the remaining 224 patients, 31 (14%) developed CHB after the procedure. Multivariate logistic regression analysis showed that female gender (odds ratio [OR] 4.3; P = 0.02), bolus injection of ethanol (OR 51; P = 0.004), injecting more than one septal artery (OR 4.6; P = 0.016), the presence of left bundle branch block (OR 39; P = 0.002), and first-degree AV block (OR 14; P = 0.001) on the baseline ECG are independent predictors of CHB after NSRT. Patients requiring PPM placement had a similar improvement in their NYHA functional class, septal thickness reduction, LVOT gradient reduction, and improvement of exercise capacity when compared with patients who did not require pacing. CONCLUSIONS: Multiple demographic, electrocardiographic, and technical factors seem to increase the risk of CHB after NSRT. Patients with CHB after NSRT derive similar clinical and hemodynamic benefit to patients who did not require permanent pacing.
The mortality rate is high from advanced atrioventricular block associated with acute myocardial infarction. There is reason to believe that if in these patients the hearts are electrically paced with an endocardial pacing catheter, the mortality rate can be considerably decreased. Five patients in second- and third-degree heart block associated with acute myocardial infarction were paced with a considerable lowering of the expected mortality rate. Twenty-three cases from the literature are also presented and discussed. A silastic bipolar electrode catheter was used in these five cases. Four of the five cases returned to normal sinus rhythm within the first 10 days. The average duration of pacing was 6.7 days. It is the opinion of the author that second- and third-degree heart block associated with acute myocardial infarction should have a pacing catheter introduced at the earliest possible moment for continuous or demand endocardial pacing.