High-Resolution Body Surface Potential Mapping in Exercise Assessment of Ischemic Heart Disease.

Standard 12-lead ECG exercise testing is commonly used for screening of ischemic heart disease (IHD). We studied if high-resolution body surface potential mapping (HR-BSPM) during exercise offers advantages over current standards in noninvasive evaluation of IHD. This study was carried out on 90 IHD patients and 33 healthy controls. The 67-lead HR-BSPM was recorded at rest and during exercise. Twenty-one ECG parameters including classical ST criteria were compared. The effectiveness of methods was verified based on the results of SPECT and coronary angiography. The most effective parameters in the diagnosis of IHD were: amplitude parameter ΔST60 and δT parameter showing T-wave morphology changes during exercise. The sensitivities/specificities of ΔST60 and δT parameters for the HR-BSPM were 70/69 and 59/62%, while for the standard 12-lead ECG system they were: 63/62 and 59/56%. These results demonstrate the usefulness of HR-BSPM measurements during exercise. HR-BSPM resulted in higher sensitivities and specificities compared to the standard 12-lead exercise test. The advantage was partially associated with observed ischemic changes outside standard precordial leads position that were not visible when using the standard 12-lead exercise test. This justifies research into the optimization of the number and position of ECG leads in exercise testing.

Prolonged postocclusive hyperemia response in patients with normal-tension glaucoma.

BACKGROUND: It is believed that endothelial dysfunction may be a link between systemic and ocular dysregulation in glaucoma. The aim of this study was to evaluate peripheral vascular reactive hyperemia in response to occlusion test and to correlate peripheral vascular findings with retrobulbar hemodynamics parameters in patients with normal-tension glaucoma. MATERIAL AND METHODS: Forty-eight patients with normal-tension glaucoma (mean age 58.1 years, 38 women) and 40 control subjects (mean age 54.1 years, 36 women) were subjected to a brachial arterial occlusion test and color Doppler imaging (LOGIQ 9, GE Medical Systems) of the retrobulbar arteries. Finger hyperemia was assessed by using a 2-channel laser Doppler flowmeter (MBF-3D, Moor Instruments, Ltd.). Time parameters (time to peak flow, half-time of hyperemia, time of recovery) and amplitude parameters (maximum hyperemia response, biological zero) of the post-occlusive reactive hyperemia signal pattern as well as velocities and resistance index of the ophthalmic, central retinal, and short posterior ciliary arteries were evaluated and compared between study groups. RESULTS: In glaucoma patients, time to peak flow and half-time of hyperemia were significantly longer (21.4 vs. 12.0 s, p=0.02 and 74.1 vs. 44.2 s, p=0.03, respectively) and biological zero was significantly lower (2.4 vs. 3.2, p=0.01) comparing with healthy subjects. In glaucoma patients, peak-systolic and end-diastolic velocities of central retinal artery were significantly lower (12.8 vs.14.1, p=0.03 and 3.9 vs. 4.7, p=0.01, respectively) and resistance index of this artery was significantly higher (0.69 vs. 0.67, p=0.03) compared to controls. In the glaucoma group, maximum hyperemic response was negatively correlated with the resistance index of temporal short posterior ciliary arteries (r=-0.4, p=0.01), whereas in the control group half-time of hyperemia was negatively correlated with end-diastolic velocity of the central retinal artery (r=-0.3, p=0.03). CONCLUSIONS: Arterial occlusion test elicited a prolonged systemic hyperemia response in patients with glaucoma as compared with healthy subjects. Retrobulbar blood flow alterations in glaucoma patients may be related to systemic vascular dysregulation.

Evaluation of the QRS-T angle using the high-resolution 64-lead electrocardiography.

OBJECTIVE: The aim of the study was to evaluate the influence of the number of electrocardiogram (ECG) leads on the diagnostic value of TCRT (spatial QRS-T angle) parameter (12 standard ECG leads and 61 surface ECG leads were used). The TCRT parameter, which describes the spatial QRS-T angle, is a useful indicator of the risk of ventricular tachycardia (VT) and sudden cardiac death (SCD). It is usually calculated from standard 12 leads ECG. METHODS: The TCRT parameter was calculated from the three virtual orthogonal leads obtained by singular value decomposition of the averaged ECG signals. Sensitivity and specificity of TCRT parameter in identifying VT patients were tested on two groups of patients after myocardial infarction: 13 non - VT patients and 30 VT patients. Additionally 17 healthy volunteers were studied as a control group. RESULTS: Mean value (+/-SD) of TCRT parameter calculated for 61 leads was -0.80+/-0.27 for VT patients and 0.27+/-0.46 for non VT patients. For 12 standard leads TCRT mean value was -0.80+/-0.22 for VT patients and 0.27+/-0.49 for non VT patients. Sensitivity for VT patients was 87% (61 leads) and 83% (12 leads). Specificity in non-VT group was 100% for both lead sets. CONCLUSIONS: Results of the study show distinct differences in the TCRT parameter values between VT patients and non VT patients for both lead sets. The sensitivities of the TCRT parameter obtained for 61 leads and for 12 standard leads were comparable.

Microcirculation in the diabetic foot as measured by a multichannel laser Doppler instrument.

BACKGROUND: The purpose of this study was to investigate microvascular perfusion in insulin-dependent diabetic patients at various locations on the foot, and to determine which part of the foot is most sensitive to microangiopathic changes. All the parameters of postocclusive reactive hyperemia calculated from multichannel laser Doppler recordings were also evaluated to find the most valuable measure for diabetes examination. MATERIAL/METHODS: Our study involved 65 subjects divided into four subgroups: male and female controls, and male and female IDDM patients without overt complications. The measurements were performed with a multichannel laser Doppler perfusion monitor using surface probes located in the distal parts of the lower limbs. The occlusion test was performed using a cuff located on the limb above the knee. Multivariate discriminatory analysis was used to evaluate the data. RESULTS: The most valuable data were obtained by recordings from the laser-Doppler probes located on the hallex and the base of the little toe. The maximum hyperemic response for both sex subgroups was significantly lower in the diabetic patients. The time to peak flow was higher in male diabetics. The half-time for hyperemia was significantly longer in the male diabetic patients. CONCLUSIONS: The females showed smaller changes in foot perfusion than the males, probably due to protection by estrogens. The best locations for perfusion measurement are the most distal, especially the hallex and the base of the little toe. The most valuable parameters of postocclusive hyperemia were maximum response, time to peak flow, and half-time of hyperemia.