Relative importance of electrode placement over number of channels in transient myocardial ischemia detection by Holter monitoring

Signal quality in a three-channel ambulatory electrocardiographic monitoring system

BACKGROUND

Ambulatory electrocardiographic recordings are not infrequently hampered by technical artefacts. Verification of good original signal level and an adequate number of ECG channels should enhance the quality.

METHODS

Data from all three-channel (mV5, mV1, III) recordings in Peijas hospital during one-calendar year were prospectively collected. A total of 255 recordings (24 h n = 239, and 48 h n = 16) made for 247 patients were analysed. Relative signal strength number (integer scale 5-0) was registered during hook-up. Final quality of recordings were afterwards evaluated with a three-point semi-quantitative scale by an experienced physician.

RESULTS

The signal strength number was adequate (>or=3) in all 241 available cases. Distribution of signal strength did not significantly vary between ECG channels. The overall quality of recordings was 'good' in three-fourth of the cases and only were they seldom 'poor'. Signal strength and quality ratings were not significantly interrelated. The quality was, as expected, better in 24 h recording than in 48 recordings, and it was also better in channel III than in channel mV5.

CONCLUSIONS

The original signal strength level (impedance) is not a crucial fact in ambulatory electrocardiographic recordings as long as it is within (specified) acceptable limits. In terms of quality, a third (inferior) ECG channel is recommendable.

Ability of heart rate variability to predict prognosis in patients with advanced congestive heart failure

We analyzed heart rate variability from normal RR intervals in patients with advanced congestive heart failure. Although most patients had decreased HRV, patients with a life-threatening cardiac event or death (n = 8) within 18 months had significantly lower heart rate variability than those who did not (n = 18), which may have value in determining prognosis in this population.

Electrocardiographic and signal monitoring in ischaemic heart disease: state of the art and perspective

The current role of ECG and signal monitoring in the diagnosis of Ischaemic Heart Disease is outlined in relation to imaging techniques giving accurate information on myocardial anatomy and function. ECG monitoring during stress testing remains the first step non-invasive method providing pathophysiological information. Long term continuous monitoring of the ECG and of other signals (e.g. arterial blood pressure and respiration) is commonly used to control patients with suspected or ascertained IHD. Progress of technology and of signal processing methods are driving the exploitation of signal information for diagnosis, prognosis and therapy control of ischaemic patients.

The inverse Nehb J lead increases the sensitivity of Holter electrocardiographic monitoring for detecting myocardial ischemia

A major reason for the relatively low sensitivity of Holter electrocardiography (ECG) for detecting ischemia is that the sensitivity of bipolar leads used for Holter ischemia monitoring has not been systematically evaluated, making lead selection difficult. Therefore, this study evaluated the sensitivity of 6 bipolar Holter leads for detecting ischemia during percutaneous transluminal coronary angioplasty. Seventy-five patients, each of whom had > 1 mm ST-segment elevation on an intracoronary electrocardiogram from the myocardium distal to the stenosis during balloon occlusion, were studied for the occurrence of > or = 1 mm ST-segment elevation or depression on the simultaneously recorded Holter leads II, III, aVF, CM5, CR4, and inverse Nehb J. The study found that the inverse lead Nehb J provided a significantly higher overall sensitivity for detecting myocardial ischemia than Holter leads II, III, aVF, CM5, and CR4. Also, the use of inverse lead Nehb J significantly increased the sensitivity of 2- and 3-lead Holter ischemia monitoring. These findings were based on a significantly higher sensitivity of inverse lead Nehb J for detecting ischemia induced by transient occlusion of the left anterior descending coronary artery and a slightly higher sensitivity for detecting ischemia induced by occlusion of the left circumflex coronary artery. None of the bipolar leads studied provided a very high sensitivity for detecting ischemia induced by occlusion of the right coronary artery. These findings show that adequate lead selection can increase the sensitivity of Holter ischemia monitoring. Furthermore, the lack of a highly sensitive lead for detection of inferior ischemia indicates that further evaluation of bipolar leads is warranted.