The Thermocross: a simple tool for rapid assessment of thermal sensation thresholds.

We have developed the Thermocross, a simple device for rapid assessment of thermal sensitivity, tested it on healthy subjects and diabetic patients and evaluated its use in identifying patients whose sensation loss may expose them to the risk of neuropathic foot injury. Thermal discrimination deteriorated with age (P less than 0.001) in healthy subjects, but all the controls could detect a temperature difference less than or equal to 10 degrees C. In diabetic patients, the deficit in thermal sensation detected by the Thermocross paralleled the decline of nerve conduction. Thermocross thermal sensation was impaired in 87% of 38 ulcerated feet of 26 diabetic patients. We conclude that the Thermocross is a suitable tool for screening for sensation loss and that diabetic patients with impaired thermal sensation are vulnerable to ulceration. The Thermocross could also serve a useful educational purpose, the implications of reduced thermal sensation probably being more meaningful to patients and health care personnel than those of a reduction in the traditionally tested vibration sensation.

Beat-to-beat detection of ventricular late potentials with high-resolution electrocardiography.

To detect dynamic changes of VLPs we developed a low-noise, HR-ECG with a gain of 10(5)-10(6)X. This system allows the beat-to-beat detection of low-amplitude signals at the bedside in a nonshielded room without any averaging process. Analysis was performed in 39 normal subjects (group A: 27 men, 12 women, mean age, 28 +/- 8 years), in 98 patients with coronary artery disease without documented sustained ventricular tachycardia (group B: 86 men, 12 women, mean age, 59 +/- 10 years) and in 41 patients coronary artery disease with sustained monomorphic ventricular tachycardia (group C: 36 men, 5 women; mean age 63 +/- 9 years). Comparison was made with time-domain signal-averaging (SA-ECG) in all cases at the same electrode position and with identical band-pass filtering. In group A no VLPs were detected; the total filtered QRS duration was 84 +/- 8 msec (mean +/- SD), and the time interval during which the terminal QRS did not exceed 40 microV (I-40) was less than 30 msec in all cases (mean, 17 +/- 6 msec). In group B, VLPs were detected by HR-ECG in 34 of 98 patients (35%); the total QRS duration was 102 +/- 16 msec (mean +/- SD, p less than 0.01 vs group A), and the I-40 was 29 +/- 13 msec (mean +/- SD, p less than 0.01 vs (group A). In group C, VLPs were detected by HR-ECG in 38 of 41 patients (93%); the total QRS duration was 123 +/- 22 msec (mean +/- SD, p less than 0.01 vs group A and group B), and the I-40 was 40 +/- 14 msec (mean +/- SD, p less than 0.01 vs group A and group B). Concordant results between HR-ECG and SA-ECG were observed in 91% of the cases (59 positive and 103 negative results). Late potentials that exhibited dynamic variations were detected by HR-ECG alone in 13 cases, and very low amplitude VLPs were detected by SA-ECG alone in three cases. In conclusion, the present study demonstrates the feasibility of body-surface recording of VLPs on a beat-to-beat basis, without any averaging process, at the bedside in a nonshielded room. This new approach may allow the study of dynamic changes of VLPs during spontaneous ventricular arrhythmias or ischemia.

Prognostic significance of ventricular late potentials in coronary artery disease.

By means of high-gain ECG and signal-averaging techniques, we tried to determine the prevalence and prognostic significance of ventricular late potentials (VLPs) in coronary artery disease (CAD). No VLPs were detected in normal subjects (n = 25) or in patients with various noncoronary cardiopathies with sustained ventricular tachycardia and/or fibrillation (VT/VF) (n = 10). Among 92 CAD patients, VLPs were apparent in 35% (32 of 92) at the beginning of the study. The prevalence of VLPs increased to 48% (19 of 40) in the presence of ventricular aneurysm (VA) and to 82% (14 of 17) in the presence of a history of previous sustained VT/VF. To determine the prognostic significance of VLPs, a prospective analysis was conducted during a mean of 7.4 months (range 1 to 22 months). During the follow-up period, 11 patients (12%) presented with an episode of sustained VT/VF, and six of them died from documented VT/VF. Three other patients died from cardiogenic shock. An episode of sustained VT/VF occurred in 31% (10 of 32) of the patients with VLPs vs 2% (1 of 58) of the patients without VLPs (p less than 0.001), and six patients with VLPs died from sustained VT/VF vs none in the group of patients without VLPs (p less than 0.01). This VLP-related increase in arrhythmic risk was still present in the particular subgroup of patients with a history of previous sustained VT/VF (n = 17) and in patients with VA (n = 40). The risk of developing sustained VT/VF was also influenced by the length of the VLP and by a low mean ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

[Late potentials: non-invasive detection in coronary disease and relation to severe ventricular arrhythmia]. / Potentiels tardifs: détection non-invasive dans la maladie coronarienne et relation avec les arythmies ventriculaires graves.

Using high-gain amplification and signal averaging techniques, we tried to determine the clinical significance of ventricular late potentials (LP). 85 subjects were included in this study. No LP were detected in normal subjects (n = 25), nor in patients with various non-coronary cardiopathies who had presented ventricular tachycardia and/or fibrillation (VT/VF) (n = 10). LP were recorded only in patients with coronary heart disease (CHD) (n = 50). The prevalence of LP was 50% (9/18) in patients with a history of VT/VF (vs 12.5% = 4/32 in patients without such a history, p less than 0.02). We also found a prevalence of 50% (11/22) in patients with a ventricular aneurysm (vs 7.1% = 2/28 in patients without an aneurysm, p less than 0.01). The prevalence reached 80% (8/10) in patients with VT/VF and a ventricular aneurysm and it was only in this latter group of patients that the interval between the peak of the R wave and the end of ventricular electrical activity exceeded 100 ms (mean 111.2 +/- 12 ms, vs 50 +/- 8 ms in normal subjects, p less than 0.001). In all the cases submitted to surgery, the LP disappeared after resection of the aneurysm. In conclusion, LP, when of long duration, should be considered as a hallmark of malignant ventricular arrhythmias in patients with CHD.

[Prognostic value of the late potentials of ventricular activation in coronary disease]. / Valeur pronostique des potentiels tardifs de l'activation ventriculaire dans la maladie coronarienne.

Identification of subsets of patients with coronary artery disease (CAD) who are prone to ventricular tachycardia or fibrillation (VT/VF) and to sudden arrhythmic death still represents one of the major problems in clinical cardiology today. Ninety-two patients with CAD were included in this prospective study, which was designed to assess the prognostic significance of ventricular late potentials (VLP) detected non-invasively using high-gain electrocardiography and signal averaging. The results clearly demonstrate that the presence of VLP increases the risk of VT/VF and the risk of sudden arrhythmic death in CAD patients. Because of its high sensitivity and non-invasiveness, high-gain electrocardiography should be included among the various electrophysiological investigations used to assess prognosis in CAD patients.

[Non-invasive detection of late potentials of ventricular activation: identification and significance in coronary disease]. / Détection non invasive des potentiels tardifs de l'activation ventriculaire: identification et signification dans la maladie coronarienne.

Using a high-amplification electrocardiograph with signal averaging, an attempt has been made to determine the prevalence of delayed potentials of ventricular activation (DPVA) in coronary heart disease (CHD) and their relation to ventricular tachycardia and/or fibrillation (VT/VF). No DPVA could be recorded in normal subjects (n = 25) or in patients with various cardiopathies with VT/VF but without CHD (n = 10). DPVA have been recorded only in patients with CHD (n = 50) (all patients having undergone ventriculography and coronarography). The prevalence of DPVA is 12.5% without VT/VF, 50% with VT/VF, and 80% when these arrhythmias are associated with the presence of a ventricular aneurysm. The duration of the DPVA is also important, since it is only in the group with VT/VF and with aneurysm that the R-EVEA duration (interval between the peak of the R wave and the end of electrical ventricular activity) exceeds 100 ms. DPVA disappeared in all the cases after aneurysmectomy. The DPVA, when of long duration, can be considered a hallmark of serious ventricular arrhythmias in patients with CHD and a ventricular aneurysm.