Familial Congenital Sinus Rhythm Anomalies: Clinical and Pathological Correlations

We describe pathological abnormalities in a 72-year-old male member of a family with a congenital absence of sinus rhythm and a tendency to develop atrial fibrillation at an early age, and in a 54-year-old female member of a family with cardiomyopathy and progressive conduction system disease manifested by first-degree atrioventricular (AV) block, left bundle branch block, and atrial arrhythmias. Both patients died suddenly. The absence of sinus rhythm in case 1 could be explained by marked atrophy, degeneration, and isolation of the sinoatrial (SA) node. The SA node was also diseased in the member of the other family with atrial arrhythmias. Additional common features in both cases included: fatty metamorphosis and degenerative changes of the approaches to the SA node, the atrial preferential fibers, and the approaches to the AV node, a small AV node, degenerative changes of the bundle branches, and floppy AV valves. These findings show that the pathological substrate of familial supraventricular arrhythmias consists of a diffuse involvement of the entire conduction system, bearing resemblance to pathological findings in elderly subjects with acquired sick sinus syndrome.     

Anatomic Substrate for Congenital Atrioventricular Block in Middle-Aged Adults

Congenital atrioventricular block is usually a benign disorder not necessitating pacing. In some patients slowing of rate and/or mortality have been noted with aging. However an anatomic substrate has not been established for the progressive slowing of the escape rate. In this study we report an anatomic substrate in two such patients who were dying in congestive heart failure, ages 49 and 42, respectively. Multiple pre-mortem ECG's in both cases revealed wide QRS escape rhythms, and escape rates of approximately 35 and 28 beats/minute, respectively. Conduction system examination by serial section in both cases revealed lack of connection between the atrial septum with the peripheral conduction system with total replacement by fat of the AV nodal approaches and AV node, and advanced sclerosis of the summit of the ventricular septum which was more marked on the right side. In addition, the His bundle showed marked septation in case one and fragmentation in case two. Sclerosis of the summit of the ventricular septum involved the branching bundle and the bundle branches in both cases. In conclusion, both patients had the characteristic lesions of congenital atrioventricular block, namely replacement of the AV node and AV nodal approaches by fat, with lack of connection to the peripheral conduction system, and one also had a fragmented His bundle. In addition premature aging of the summit of the ventricular septum may have reflected the long-standing hemodynamic stresses of chronic bradycardia. This in turn resulted in trifascicular involvement of the conduction system leading to a shifting of the escape rhythm distally eventuating in a slower idioventricular escape rhythm.     

Ovarian carcinoma and digital ischaemia

A case of ovarian carcinoma presenting as digital ischaemia, with progression to gangrene, is described. The case serves as a reminder of an important association, and the potential mechanisms are reviewed.     

Diffuse Conduction Abnormalities in an Adolescent with Familial Sinus Node Disease

We report a case of familial sinus node disease with associated conduction abnormalities in the atrioventricular node and distal conduction system Spontaneous atrial pacemaker activity was absent though the atrium could be depolarized. The pacemaker activity of the heart resided in the atrioventricular junction. The AV node showed impaired automaticity and abnormal conduction properties which partially improved after vagal blockage.     

REDUCED DOPAMINERGIC INHIBITION OF THYROTROPHIN RELEASE IN STATES OF PHYSIOLOGICAL HYPERPROLACTINAEMIA

We have tested the hypothesis that physiological puerperal hyperprolactinaemia may be secondary to reduced hypothalamic dopaminergic inhibition of prolactin (PRL) release. Nine post-partum females with physiological hyperprolactinaemia (aged 19–40 years; mean basal PRL±SE, 2099±257 mU/l, range 1002–3762 mU/l) were studied and results compared with fourteen normoprolactinaemic females (basal PRL<400 mU/l; aged 18–36 years). Puerperal hyperprolactinaemic females showed a reduced TSH response to dopamine (DA) receptor blockade with metoclopramide (10 mg i.v.) compared with normal females over a 60-min period following drug administration (total incremental TSH change, mean ±SE, mU/l; 0.5±0.3 v. 3.1±1.0, P<0.005). This finding of reduced dopaminergic inhibition of TSH release in females with physiological puerperal hyperprolactinaemia supports the view that an overall reduction in hypothalamic dopaminergic tone may contribute towards hyperprolactinaemia in post-partum women.