[Trichamber pacing in dilated myocardiopathy. TTDR pacing?]. / Estimulación tricameral en la miocardiopatía dilatada. Modo de estimulación TTDR?

This article describes the first case in Mexico city that received a three chamber pacing system. A 40 year-old man with dilated cardiomyopathy with variant cardiac rhythm and bradycardia. The three leads were introduced by right subclavian approaches. The right chamber leads were placed in atrial's appendage and in the right ventricular outflow tract and the last one was placed in the great cardiac vein. The two ventricular lead were connected a Y-connector to the ventricular channel of a standard bipolar DDDR pacemaker. The right ventricular lead was connected to the distal pole (anode) and the left ventricular lead to the proximal pole (cathode). Eight days later, the patient's clinical status improved, his functional class improved from IV to II and his left ventricular ejection fraction increased from 30% to 35% by conventional ventriculography. In this type of patients the improvement in cardiac output is this result an of increase in left ventricular filling, reduced mitral and tricuspid regurgitation a better synchronization of ventricular contraction. Multisite pacing has added a mayor complexity to contemporary pacing and a modification of the standard pacer-maker code should be considered to accommodate multisite pacing. The letter in the first and second position might be T (three) or F (four) according to number of pacing chamber and also the letter "t" may be suitable to designate trigger in the third position. We conclude that implant of three chamber pacing in patients with dilated cardiomyopathy is technically feasible. An improvement in the patient's condition may be obtained and a modification in standard pacemaker code is necessary.

Densitometric analysis of the human calcaneus.

A densitometric study was performed on 50 dry calcanei to assess bone mineral density (BMD) in the constituent regions of the bone. In the lateral projection, the area with the highest BMD was the anterosuperior region, where the greatest concentration of trabeculae occurs. The areas with the least BMD were the intermediate or retrothalamic and the anteroinferior regions, where the neutral triangle is situated. In the dorsoplantar projection, a greater BMD was observed in the intermediate and middle regions, whereas the anterior region showed the lowest BMD. These results conform to the arrangement previously described for the trabecular system. It is concluded that bone densitometry, measured by dual x-ray absorptiometry, is useful for assessing trabecular architecture of the calcaneus.