Ventricular injury in acute left circumflex occlusion: Exploration using precordial bipolar leads and regional vectorcardiograms.

BACKGROUND: Precordial Bipolar Leads (PBLs) provide new electrocardiographic information derived from standard 12­lead ECG recordings. OBJECTIVES: To explore the usefulness of PBLs in patients with acute circumflex coronary artery (CxCA) occlusion. METHODS: Twelve patients undergoing elective percutaneous transluminal coronary angioplasty (PTCA) were studied before and after acute CxCA occlusion and their data were processed with new methods based on PBLs. RESULTS: The findings were: 1. In right PBL V2-V1, a strong systolic current of injury moving in the left-to-right direction coexists with a strong right-to-left current of injury displayed in left standard unipolar precordial leads (V4, V5 and V6). 2. Ischemic changes lead to a significant increase (approximately 10 ms) in the QRS duration in different leads, although changes in the QRS loop rotation and folding were absent. 3. In the transverse, sagittal, and frontal planes, superimposing two PBLs and the corresponding Regional VCG facilitates the location of the J-point. 4. In the Regional VCGs of this group of patients, J-point and ST segment shifts produced an image that reminds the Greek letter omega (Ω). 5. The currents of injury flowing in opposite directions could result in electrical cancellation that minimizes ECG changes in the standard 12­lead recordings. CONCLUSIONS: Computerized processing of digital, standard 12­lead ECG recordings, provides new valuable diagnostic data in patients with acute CxCA occlusion. The loops revealed important information related to systolic currents of injury. Because these methods use routine 12­lead ECG data, the procedure is based only in software applications. CONDENSED ABSTRACT: Twelve patients undergoing PTCA were studied before and after acute CxCA occlusion and their data were processed with the new methods based on Precordial Bipolar Leads (PBLs) to explore their usefulness. The results showed strong systolic currents of injury in different and sometimes opposite directions in the right-to-left axis and ischemic alterations in the time and amplitude of the QRS waves. The superimposition of two-dimensional coordinates planes (x-y, x-z or z-y) helped to locate the J-point and to display the Regional VCG omega sign (Ω) of myocardial injury. In conclusion, computerized processing of digital ECG data provides new diagnostic information in patients with acute CxCA occlusion.

Right ventricle injury in RCA occlusion: Exploration using precordial bipolar leads and surrogate vectorcardiograms.

BACKGROUND: Precordial Bipolar Leads (PBL) provide new electrocardiographic information derived from standard 12­lead ECG recordings. OBJECTIVES: To explore the usefulness of PBL in patients with acute right coronary artery (RCA) occlusion. METHODS: Sixteen patients undergoing elective percutaneous transluminal coronary angioplasty (PTCA) were studied before and after RCA occlusion and their data were processed with new methods based on PBL. RESULTS: The findings were: 1. In PBL V2-V1, strong systolic currents of injury moving in the left to right direction coexist with those directed towards leads II, III and aVF. 2. Changes in the time of the peaks of the QRS waves do not alter the duration of the QRS. 3. The QRS loops of the surrogate VCG generated show that, during ischemia, the time changes in the peak of the QRS waves displayed in one axis are the consequence of an increase in the amplitude of the waves observed in the perpendicular axis. 4. The use of two simultaneous dimensions (transverse and frontal planes) facilitates the location of the J-point. 5. In the surrogate VCGs of this group of patients, J-point and ST segment shifts produced an image that reminded the Greek letter omega (Ω). 6. The QRS wave changes, in time and amplitude, explained the rotational changes and the ischemic distortions of the surrogate VCG loops. CONCLUSIONS: Computerized processing of ECG data appears to provide new and valuable diagnostic data in patients with acute RCA occlusion. The loops revealed important information related to systolic currents of injury. Because these methods use routine 12­lead ECG data, the procedure is based only in software applications.

Abnormal Myocardial Activation as a Cause of ST elevation: A Study Using Precordial Bipolar Leads (PBL).

OBJECTIVES: The purpose of the study was to describe the ischemic changes occurring during percutaneous transluminal coronary angioplasty (PTCA) using a new method based on Precordial Bipolar Leads (PBL) and Precordial Unipolar Leads (PUL). BACKGROUND: Ischemic ECG changes have been attributed to both systolic and diastolic injury currents. The relation between ST-segment shift and QRS changes is unclear and there is a discussion about its significance. METHODS: Twelve-lead electrocardiograms (ECGs) were performed in 16 patients before PTCA balloon inflation and immediately after balloon deflation in the proximal left anterior descending coronary artery (LAD). Also, ECG data was used to generate V2-V1 PBL, average V1+V2 lead, and the correspondent loop to explore ECG and spatial vector changes. RESULTS: (1) The V2-V1 Vs Average V1+V2 loop rotation changed from counterclockwise (CCW) to clockwise (CW) in 14 of 15 patients (93%). (2) In 12 of 16 patients (75%), there was an abrupt change of QRS vector direction, producing a "folding" of the loop. In 10 of these cases, the change occurred between 32 and 49 milliseconds after the QRS initiation. (3) In 3/16 patients the final part of the loop was "transported", without folding, to the turning point. (4) The "folding" of the loop changed the direction of the final QRS forces and the J point and ST-segment were displaced to the left and forward. (5) For this reason, repolarization began from an abnormal anterior location. CONCLUSIONS: (1) Ischemic changes in the QRS loop have a cornerstone point in which the whole loop changes. (2) Once the loop has changed its direction, there are no major modifications in the loop development, but the forces do not aim anymore to the isoelectric point. (3) Alterations of myocardial activation appear to be responsible for ST elevation in hyperacute ischemia.

DERIVACIONES POLARES DE ECG: UNA REPRESENTACIÓN GRÁFICA DIFERENTE PARA ENSEÑAR VECTORES DE ECG E INTERPRETACIÓN / ECG Polar Leads: A Different Graphic Representation to teach ECG vectors and interpretation

Electrical activity of the heart can be presented using different methods, and the standard is ECG, in which the changes in electric amplitude in one axis are written on paper that moves at a known velocity. Vectorcardiography uses Cartesian (rectangular) coordinates and plots points defined by the simultaneous values in the x and y axes. In this paper, a new graphic display of electrical heart activity based on Polar coordinates is presented. In polar coordinates, the point is defined by the magnitude of the vector (electrical amplitude) and the angle in relation to x or y or z axes, and all the leads can be overlapped. The information used by this method is the same that for simultaneous 12 leads standard ECG and it needs no additional cables or technician labor. Polar coordinates are very good for comparison of time/amplitude mismatch in different leads, to detect the cardiac axis and to explore the impulse conduction. Also, it facilitates the learning of ECG physical basis. This method differs from the classic Dower's Polarcardiography because it uses the classic leads instead of the X, Y and Z leads, and it does not apply magnitude tracings.

Right-to-left T-wave discordance in acute myocardial infarction: A new electrocardiographic sign of apical and left lateral infarction.

INTRODUCTION: A new ECG method producing Precordial Bipolar Leads (PBL) enables a computerized subtraction of the electrical activity detected by the precordial V1 lead from that of the V6 electrode (V6-V1 PBL). This calculation can also be performed manually using measurements from standard simultaneous 12 lead ECG (SS12LECG) tracings. We compared the magnitude of T-waves generated by PBL V6-V1 (measured by computer) to the SS12LECG V6-V1 T-waves (measured on the tracing) to determine whether these measurements are equivalent. Although Lead I and Lead V6-V1 PBL examine almost the same right-to-left axis, we noted that Lead I and Lead V6-V1 PBL sometimes have opposite T-wave polarities. We investigated this observation further using a database containing control and patient data. MATERIAL AND METHODS: Records of 79 patients and 52 controls from the Physionet database were used to generate the V6-V1 PBL for comparison to manual calculations from the V1 and V6 unipolar T-wave measurements on the tracings. The accuracy of these measurements was validated against the computer measurements by correlation and paired t-tests. RESULTS: The T-wave automated and manual measurements in patients were strongly correlated (0.9895), consistent with the premise that measurements from tracings are accurate. The V6-V1 T-wave calculation was positive in 48 of the 52 control subjects. Nearly half of the acute myocardial infarction (AMI) patients had discordant T-wave polarity between Lead I and V6-V1 PBL; ventriculography results on 24 of these patients identified 13 patients with apical and 11 with lateral wall motion abnormalities. CONCLUSION: A discordant T-wave in Lead I and in the V6-V1 PBL is a potential diagnostic criterion for apical or left-lateral infarction.

Nuevos Métodos Electrocardiográficos: Un Estudio Basado en Electrodos Bipolares Precordiales / NEW ELECTROCARDIOGRAPHIC METHODS: A NEW STUDY BASED IN PRECORDIAL BIPOLAR ELECTRODES

En este artículo se presentan varios métodos nuevos de exploración electrocardiográfica. Todos ellos se basan en la modificación del procesamiento de la información que rutinariamente recoge el ECG standard de 12 canales, sin electrodos o cables adicionales. Se basan en derivaciones bipolares precordiales que miden el desfase en tiempo y amplitud entre los electrodos que van de V1 a V6, y muestran, en forma magnificada y con mucho más detalle, las anormalidades en el eje derecha a izquierda (como lo hace DI). El ECG se realiza rutinariamente y sus resultados son los trazados habituales. No obstante, usando los datos ya recogidos, se obtienen derivaciones precordiales bipolares, coordenadas polares, subderivaciones y derivaciones ponderadas nuevas. Los nuevos trazados permiten apreciar con claridad fenómenos difíciles de apreciar en los trazados de rutina del ECG de 12 canales.

Several new methods of electrocardiographic exploration are presented in this work. All are based on processing the information already obtained when a standard 12-channel ECG is performed. They need no additional electrodes or cables. They are based on precordial bipolar leads measuring time - amplitude mismatch among V1 to V6 unipolar electrodes, and present, with much more detail and magnified, abnormalities on the right to left axis. ECG is performed in the usual way producing the classic 12 tracings. However, using the data already collected, bipolar precordial leads, polar coordinates, sub derivations and new weighted derivations can be obtained. The new methods allow seeing clearly some phenomena difficult to appreciate in the routine tracings of the 12-channel ECG.

Precordial bipolar leads: A new method to study anterior acute myocardial infarction.

INTRODUCTION: A new ECG method produces Precordial Bipolar Leads (PBL) generated by subtraction of measurements of Standard Precordial Unipolar Leads (SPUL). This procedure brings new information about time/amplitude mismatch among SPUL, presenting it as tracings and local VCG loops exploring the precordial left-to-right axis on the horizontal plane. In this study, results of V2-V1 bipolar precordial derivation V2-V1 (right to left) and its relationship with the anteroposterior axis are presented. MATERIAL AND METHODS: Records of 37 patients and 15 controls from Physionet database were used to create new PBL and compare between V1 and V2 SPUL. So, bipolar V2-V1 was obtained by subtracting V1 measurements from V2, always having as positive the V2 SPUL and as negative V1. The algorithm used was subtracting, in every millisecond, the voltage recorded by the right electrode from the simultaneously recorded left electrode. Combination of SPUL and PBL can be presented as tracings or local loops, showing detailed information of the electric horizontal plane of the heart at retrosternal location. PBL V2-V1 reflects right ventricle and septal electric activity. RESULTS: The new method is able to detect changes in vectors and differences of milliseconds between SPUL and presents new and important information about the right-to-left electric axis. Right ventricle and interventricular septum electric activity can be differentiate in anterior AMI and LBBB. CONCLUSION: Time/amplitude mismatch between SPUL could be the source of abundant and new information about cardiac depolarization and repolarization. As data to obtain PBL and new loops are already obtained in any ECG device that records simultaneously 12 leads, the system can be added to ECG software algorithms without any additional cable or recording work.

Pulsed Doppler in simulated compartment syndrome: a pilot study to record hemodynamic compromise.

BACKGROUND: Acute compartment syndrome occurs when the tissue pressure within a closed muscle compartment exceeds the perfusion pressure. We observed diastolic retrograde arterial flow (DRAF) in 2 patients in the arteries proximal to compartment syndromes in injured limbs. We hypothesized that DRAF may represent an early sign of compartment pressure increments. METHODS: We mimicked compartment syndrome by using a cuff to produce external compression of the forearm at increasing pressures. We correlated the applied pressure with brachial artery blood flow, velocities, and retrograde flow. We studied the brachial artery at baseline, at external compression of 40 mmHg applied to the forearm, at forearm compression equal to the patient's diastolic blood pressure (DBP), and at forearm compression equal to the patient's mean arterial pressure (MAP). Evaluations included Doppler velocities and DRAF percentage (%). Using a ROC analysis, we selected a DRAF (%) cutoff value for the identification of patients with an applied external pressure equal to or greater than their DBP and calculated its sensitivity and specificity. RESULTS: Compared with baseline, DRAF (%) was increased at 40 mmHg (P<0.05), at DBP (P<0.05), and at MAP (P<0.05). DRAF (%) was strongly correlated with applied external pressure (r=0.92, r(2)=0.85). DRAF 40% presented a 100% sensitivity and a 93% specificity for identifying a compression equal to or greater than the patient's DBP. CONCLUSION: DRAF (%) strongly correlates with the degree of external pressure applied to the brachial artery, suggesting it may represent a useful tool in the detection and evaluation of compartment syndrome.

Diastolic retrograde arterial flow and biphasic abdominal aortic Doppler wave pattern: an early sign of arterial wall deterioration?

Many authors have found that diastolic retrograde arterial flow is associated with increased stiffness of the arterial wall. Most of the studies were based in femoral or brachial artery examination. As the abdominal aorta is a large vessel routinely explored in abdominal ultrasound scans, we decided to study whether it could be useful for early identification of abnormalities of the arterial wall. Sixteen young and 16 old, healthy patients matched for sex, weight and height were studied using pulsed Doppler at the level of the abdominal aortic bifurcation. Different hemodynamic factors were measured and compared to establish the systolic and diastolic function of this artery. Triphasic wave pattern was present in 14 of 16 patients in the younger group and only in 4 of 16 in the older group. In addition, diastolic retrograde arterial flow duration and retrograde components of diastolic phase were more prominent in the advanced age group. Increased retrograde flow and incapacity to impulse arterial flow forward during diastolic time are early markers of vascular wall deterioration that can be observed easily in the abdominal aorta during routine abdominal ultrasound scans.

Retrograde flow components in the brachial artery. A new hemodynamic index.

Arm elevation induces diastolic retrograde flow in the brachial artery and an incremental rise in arterial compliance in healthy subjects with no modifications in vascular resistance. In contrast, changes in resistance have been observed after handgrip exercise. Our objective was to investigate if the resistance change induced by isometric handgrip exercise is able to reverse diastolic retrograde flow induced by arm elevation in a healthy population and to explore these adaptive changes in hypertensive subjects. Arterial flow velocity Doppler measurements were obtained including: (a) a baseline measurement, (b) measurement 30 s after arm elevation, (c) measurement during handgrip maneuver with the arm elevated, (d) measurement during handgrip release with the arm elevated. Our findings showed that diastolic retrograde flow is induced by arm elevation, partially increased by arm-up handgrip and completely reversed during arm-up handgrip release both in healthy and hypertensive subjects. As compared with normal subjects, deceleration time was longer in the hypertensive subjects during baseline but not during the arm-up stage, handgrip contraction and handgrip release stages. An important increase in deceleration time values from baseline to arm-up and handgrip contraction stages was observed in normal subjects but not in the hypertensive group. We believe that the highly significant difference in reactivity to postural changes observed in deceleration time values constitutes a promising hemodynamic index to investigate. Also, our observation of complete reversal of the retrograde flow during arm-up handgrip release provides a new approach to postural and exercise-induced vasomotor responses.