• Clinical location of the fourth and fifth intercostal spaces as a percent of the length of the sternum

      Marcus, Frank; Hughes, Trina; Barrios, Phillip; Borgstrom, Mark; Univ Arizona, Coll Med, Sarver Heart Ctr, Div Cardiol; Univ Arizona, Res Comp UITS (CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS, 2018-01)
      Objectives: To verify accurate placement of the precordial ECG leads by identifying the 4th and 5th intercostal spaces as a function of the length of the sternum. This should decrease the percentage of lead misplacement leading to misdiagnoses. Methods: The population consisted of patients and healthy volunteers. The proposed method compared palpation of the 4th and 5th intercostal spaces to a percentile of the sternal length. Location of the 4th and 5th intercostal space using a simple device was evaluated to assist in proper placement of the precordial leads to obtain accurate diagnosis. Results: The location of the 4th and 5th intercostal space is related to the length of the sternum. It is 77% of the sternal length that measures 15 cm for the 4th intercostal space. The position of the VI and V2 electrodes decreases to 57% when the sternal length is 26 cm. Similar data was obtained to locate the 5th intercostal space with proper position of V4-V6 electrodes. Tables are provided to facilitate this process. An instrument was designed to measure the 4th and 5th intercostal space as a function of the sternal length. Conclusions: The location of the 4th and 5th intercostal space is identified based on the length of the sternum. (C) 2017 Elsevier Inc. All rights reserved.
    • Electrical and mechanical alternans during ventricular tachycardia with moderate chronic heart failure

      Chinyere, Ikeotunye Royal; Moukabary, Talal; Goldman, Steven; Juneman, Elizabeth; Univ Arizona, Sarver Heart Ctr (CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS, 2018-01)
      A chronic heart failure (CHF) rat underwent epicardial programmed electrical stimulation (PES). Ventricular tachycardia (VT) developed during PES. Mechanical alternans was noted despite fixed tachycardia cycle length. Anti-tachycardia pacing attempts initiated a second VT that generated pulse intermittently and then degenerated into pulseless VT with electrical alternans. To our knowledge electrical and mechanical alternans have not been recorded in animal models of CHF during VT. The distinct events of mechanical alternans and electrical alternans may be indicative of progressively worsened calcium handling in the compromised cardiomyocytes. Although ion channel differences between rodents and humans exist, this work attempts to demonstrate this rat model's usefulness in understanding cardiac electrophysiology in CHF. (C) 2017 Elsevier Inc. All rights reserved.
    • High incidence of ST-T changes in women during tilt-table testing

      Suryanarayana, Prakash Goutham; Kandala, Jagdesh; Marcus, Frank I.; Univ Arizona, Div Cardiol, Sarver Heart Ctr (CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS, 2017-11)
      Introduction: We have observed electrocardiographic (ECG) changes primarily in women during tilt table testing. Methods: We reviewed 12 lead ECGs during tilt studies between 2012 and 2016 for changes in ST segments and T waves during tilt table testing. Patients with distinctly abnormal baseline ECGs were excluded. Results: Of the 180 tilt studies, 117 (65%) were in women. There were 32 patients with ECG changes during tilting. Of these, 28 (87.5%) were in women with an average age of 45 years. None had a history of CAD or exertional chest pain. Echocardiograms were available in 21 of the 28 women with tilt induced ECG changes and all were normal. ECG changes during tilt table testing were found in 4/64 (6.25%) of men. The occurrence of ST-T wave changes during tilt testing was significantly higher among women compared to men, with a p value of 0.008. Of the 28 women with ECG changes during tilt, 11 had T wave inversions alone. ST segment depression alone was noted in 7 women. There were 10 women who had both ST segment depression and T wave inversions. Changes occurred immediately upon tilting in 6. In the remaining, they occurred at an average of 4.8 +/- 4 min after tilting. The slight increase in heart rate in patients with ECG changes was similar to that in the patients without new ECG changes. The ECG changes were not related to the presence of syncope. Conclusions: ECG changes during the testing was observed at a relatively high incidence primarily in women. The clinical significance of these repolarization changes during tilt testing is unknown. These ECG changes during tilt testing may correlate with the high incidence of false positive ECGs in women during exercise testing but do not necessarily indicate the presence of ischemic coronary disease. Additional research is needed to explain this phenomenon. (C) 2017 Elsevier Inc. All rights reserved.