Chest leads

Conscious studies using devices for measurement of blood pressure and six chest lead ECG measurements (V2, V4, V6, V10, rV2 and rV4). ECG interval analysis is performed on the V2 lead (RR, PR, QT, QTc intervals, QRS duration). QT dispersion can also be measured. Locomotor activity can be monitored and behavior captured on video using CCTV. 

Conscious studies using DataSciences telemetry for blood pressure and lead II ECG or the ITS system for blood pressure and six chest lead ECG measurements (including QT dispersion). 

Narrow QRS Nonspecific ST-T changes in anterior chest leads, shortened ST-segment Fusion of T-wave into QRS, sharp rise of T-wave Sinus tachycardia, acidosis with high anion gap Chin et al. (2000) (man)... 

A routine ECG is composed of 12 leads. Sis are called limb leads (I, II, III, aVR, aVL, and aVF), because they are recorded between arm and leg electrodes, and six are called precordial or chest leads (Vj, V2, V3, V4, V5, and Vg) and are recorded across the sternum and left precordium. Each lead records the same electrical impulse but in a different position relative to the heart. Areas of pathology shown on the ECG can be localized by analyzing differences between the tracing in question and what is known to be normal in the 12 different leads. 

Matetzky S, Freimark D, Feinbergt MS et al. Acute myocardial infarction with isolated ST-segment elevation in posterior chest leads V7-9 hidden ST-segment elevations revealing acute posterior infarction. J Am Coll Cardiol 1999 34 748. 

FIGURE 24.1 The 12-lead ECG is formed by the three bipolar surface leads I, II, and III the augmented Wilson terminal referenced limb leads aVR, aVL, aVF and the Wilson terminal referenced chest leads Vi, V2, V3, V4, V5,... 

Proper electrode placement is the single most important fector for determining whether transcutaneous pacing will be effective. The proper position of the cathode (negative) electrode is directly over the cardiac apex or over the position of ECG chest leads V3 (Fig. 7.1). The anode (positive) electrode is placed either posteriorly (recommended) on the back between the spine and the lower half of the left or right scapulae, or, alternatively, if the back is inaccessible, over the right upper chest centered approximately 6-10 cm above the... 

A 78-year-old man developed anaphylaxis after exposure to peanuts and was given intramuscular adrenaline 0.5 mg with very good response. However, very shortly afterwards he became sweaty and nauseated, without chest pain, but with a tachycardia of 107/ minute and ST segment elevation in the anterior chest leads of the electrocardiogram. He had has a stent inserted for established coronary artery disease in the left anterior descending artery 4 years earlier. Cardiac catheterization showed occlusion of the same artery, without apparent restenosis. 

To record a 12-lead ECG, place electrodes on the patient s arms and legs (with the ground lead on the patient s right leg). The three standard limb leads (I, II, and III) and the three augmented leads (aVp, aV, and aVp) are recorded using these electrodes. Then, to record the precordial chest leads, place electrodes as follows ... 

To record the right precordial chest leads, place the electrodes as follows ... 

Normal 12-lead ECG recorded with standard lead positioning Same ECG with limb leads swapped over. Note positive aVR while lead I, II and aVL are now negatively deflected Misplaced chest leads causing a change in R wave progression Somatic muscle tremor in multiple leads, seen predominantly in leads II and III... 

The voltage was later boosted creating the augmented voltage leads known as aVR, aVL and aVF. Subsequently the six unipolar chest leads were also created to view the heart from the frontal plane in a horizontal view (Fig. 2.6). 

Fig. 3.6 Misplaced chest leads causing a change in R wave progression...

A) That the chest leads have been misplaced... 

The potential presence of LVH is identified by an increase in the QRS voltage (Fig. 5.10), this is due to the increased muscle mass of the hypertrophied left ventricle (Fig. 5.11). There are many different scoring systems and criteria identified in the texts for detecting LVH (e.g. Romhilt-Estes scoring system, Sokolow-Lyon criteria, Cornell criteria, etc.). For the purpose of this introductory text, only two methods are shown, one using the limb leads and the other using the chest leads. 

MCLj (modified chest lead) and MCL (similar to the unipolar leads Vj and Vg of the 12-lead ECG). 

Lung and muscle barriers prevent usual chest leads from seeing and recording damage on posterior surface of heart. 

This 12-lead electrocardiogram shows typical traits of a right-ventricular-wall myocardial infarction (Ml). Note the ST-segment elevation in the right precordial chest leads V41 , Vji , and Pathologic Q waves would also appear in leads V4K,... 

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