Ventricular arrhythmias on exertion

N° 6
Manufacturer Biotronik Device ILR Field Biomonitor

82-year-old woman with ischemic cardiomyopathy participating in the LBBB-TAVI study; palpitations and lipothymia during moderate exertion.

Graph and trace

Tracing 6a: episode diagnosed as HVR;

  1. sinus tachycardia;
  2. PVC;
  3. sudden acceleration of the ventricular rhythm with tachycardia at 190 beats/minute, stable with modification of the QRS complex pattern relative to the sinus rhythm; identical pattern to that of the PVC; HVR classification;

Patient: 85-year-old man participating in the LBBB-TAVI study.

Tracing 6b: episode diagnosed as HVR;

  1. probable sinus rhythm (difficulty in properly discerning the P waves);
  2. sudden acceleration of the ventricular rhythm with stable tachycardia (190 beats/minute) with modification of the QRS pattern; HVR classification;
  3. spontaneous termination.

These 2 tracings are evocative of a ventricular rhythm disorder, sustained in the first instance and non sustained in the second. One of the difficulties in interpreting implantable loop recorder tracings is that there is only one lead and that the differentiation between ventricular tachycardia and supraventricular tachycardia is sometimes hazardous in the sense that the analysis of per-tachycardia atrial activity is most often impossible. Similarly, variations in morphology of the QRS complexes may be limited in this single lead. The therapeutic consequences are obviously significant since the demonstration of a symptomatic and sustained rhythm disorder must evoke the prospect of ICD implantation. In the second patient (NSVT), a beta-blocker therapy was introduced. The first patient underwent coronary angiography, which did not reveal any lesions potentially generating ischemia leading to a ventricular arrhythmia. During hospitalization, this patient presented a sustained and syncopal episode of ventricular tachycardia suggesting that the implantable loop recorder recording most likely corresponded to a ventricular rhythm disorder. The patient underwent implantation of an ICD with an increase in beta-blocker treatment.

Two parameters must be programmed in order for the device to trigger a recording on a high ventricular rate (HVR): 1) rate limit: programmable between 110 and 200 beats per minute with a nominal value of 180; 2) fast interval counter: programmable between 8 and 64 with a nominal value of 16; the counter is incremented for each interval exceeding the programmed limit value (+1) and is decremented for each slower interval (-1); when the counter is filled, an HVR episode is diagnosed; when noise is sensed (interval classified as Vn), the counter is systematically reset to 0 to avoid memory saturation due to oversensing; the episode is considered as terminated by the device when 5 consecutive intervals are slower than the programmed rate (intervals classified as Vn have no effect on the end-of-episode counter).