Baseline vectorcardiography as a predictor of invasively determined acute hemodynamic response to cardiac resynchronization therapy.

Aims: Identifying potential responders to cardiac resynchronization therapy (CRT) may be sometimes difficult and time consuming. Searching for a simple method, we chose vectorcardiography (VCG) for our study. The aim was to evaluate whether a VCG parameter can be used to predict invasively measured acute hemodynamic changes after CRT onset.

[Three-dimensional vectorcardiography to predict CRT-responder].

Cardiac resynchronization therapy (CRT) is an accepted treatment for congestive heart failure (NYHA III-IV), but a substantial number of patients show no response to therapy. LBB, QRS width and echocardiographic measurements are parameters for indication, but they are not valid to predict hemodynamic response. A new method based on vector ECG analysis can deliver additional information, such as: parts or areas with late excitation, and with slow or fast depolarization speed.

[Basics of electrical cardiac stimulation].

An essential part of a pacemaker system is the lead with a stimulation and sensing electrode. Both funtions, which are completely different processes, are performed by the same electrode. Requirements for a pacemaker lead are: outstanding bio-compatibility, low pacing threshold, reliable sensing, high pacing impedance, low polarisation and corresponding longterm stability.

[A simple method for AV-delay determination in dual chamber pacemakers].

The individual adjustment of the AV intervals is a prerequisite for the hemodynamic advantages of dual-chamber pacing. The methods for the optimization of the AV-Delay (AVD) applied so far are time intensive. A simple and fast method is the approximate adjustment of the AVD with the surface-ECG.

Exercise induced sympathetic influences do not change interatrial conduction times in VDD and DDD pacing.

Using telemetry, right atrial electrogram (RA), and marker channel of atrial sense events (MA) in combination with the left atrial electrogram (LA), recorded by a filtered bipolar esophageal lead, interatrial conduction during submaximal exercise and at rest was examined in 46 DDD pacemaker patients. The RA-LA and MA-LA conduction times measured in the presence of atrial sensing (VDD) as well as the conduction time SA-LA from atrial stimulus (SA) to LA, determined during atrial pacing (DDD) were found to be individual constants independent of exercise induced sympathetic influences. Thus, having determined an optimal mechanical interval (LA-LV)mech/opt from left atrium to ventricle by other methods, the optimal AV delay for DDD as well as for VDD operation can be calculated by the sum of the appropriate interatrial conduction time (SA-LA, respectively MA-LA) and the (LA-LV)mech/opt interval.