Relationship between hair elements and severity of atrioventricular block in horses

The aim of this study was to investigate the relationships between the mean concentrations of trace elements and the severity of the seconddegree atrioventricular (AV) block in the mane hair of horses. Electrocardiographs of horses were continually recorded for 6 h using a holter cardiac monitor to determine dropped ventricular beats (DVBs) which can be used as an indicator of the severity of the AV block. Mane hair Ca, Cu, Mg, and Zn concentrations were measured by the particle-induced X-ray emission method. The Zn/Cu ratio and Ca concentration in mane hair were significantly and positively correlated with the hourly DVBs in horse with a second-degree AV block (p<0.01, r2=0.485; p<0.05, r2=0.351, respectively). Proposed diagnostic cutoff points for hair Ca concentration and Zn/Cu ratio based on receiver operating characteristics curves analysis in detecting second-degree AV block were set at 1536 μg/g and 26.0, respectively. Those results with horse hair suggest that the evaluation of the Ca, Cu, Mg, and Zn status in mane hair by this method is strongly related to the severity of second-degree AV block and might predict the susceptibility of an individual much before the development of the symptom.     

Hypothyroidism as the cause of atrioventricular block in an elderly patient

Syncope is a common problem in the older patient. Sometimes syncope is caused by extreme bradycardia secondary to atrioventricular (AV) block. We describe a case in which a 90-year-old woman presented with complete AV block due to severe hypothyroidism. After suppletion with levothyroxine, AV conduction was restored. (Neth Heart J 2008;16:57-9.)     

An unusual case of complete atrioventricular block causing Takotsubo syndrome

Complete atrioventricular (AV) block in association with Takotsubo syndrome (TS) has been well recognized, but the cause and effect relationship has not been elucidated. We describe a 78-year-old female who presented with complete AV block but one week later developed new-onset, diffuse T-wave inversions, QT prolongation, and acceleration of junctional escape rate. Left ventriculogram revealed features typical of TS. One year after permanent pacemaker implantation, complete AV block persisted despite the reversal of wall motion defects implying that conduction abnormality was the trigger of TS rather than its consequence.     

Activation of the right atrioventricular valve in the avian heart

Using intramural needle electrode, in situ determinations have been made of the moment of activation of the right muscular atrioventricular valve during electrical systole of the heart. In the hen, Gallus domesticus, the electrical activation of the valve was observed 8.8 +/- 1.4 ms (mean QRS duration 25 ms) whereas in the pigeon Columba livia--5 +/- 1 ms (QRS duration 17 ms) after the beginning of ventricular depolarization, i.e. during excitation of the main bulk of the myocardium of the free wall of the right ventricle.     

An extra atrioventricular node in an anomalous heart of a calf

An extra atrioventricular node in a double outlet ventricle with a quite normal inflow septum in a calf is described. The anomaly resembles the topography of the conducting system in the calf heart in the embryonic stages from 13.5 mm-90 mm.