Original Article
Bioimpedance-derived Differences in Cardiac Physiology during Exercise Stress Testing in Low-risk Chest Pain Patients
Abstract
Background Little has been written about the utility of thoracic electrical bioimpedance (TEB)-derived cardiac physiologic variables in evaluating patients with low-risk chest pain syndromes. Noninvasive bioimpedance can monitor cardiac physiology while a patient is performing an exercise stress test. In addition, the demographics of patients with chest pain, the incidence of coronary artery disease (CAD), and the methods used for evaluation have well-documented sex differences. Objective The objectives are to show that there are different cardiac physiologic responses to exercise stress test in Chest Pain Evaluation Unit patients with and without true CAD that could be used to stratify patients and that there is a sex difference in TEB results. Methods Patients 18 to 65 years of age with low-risk chest pain were eligible. Patients were attached to the TEB throughout the exercise stress test procedure. Heart rate (HR) was monitored. Primary dependent variables were TEB-measured cardiac output (CO, L/min) and stroke volume (SV, ml) at peak exercise. Secondary variables were TEB-measured ejection fraction (%), end-diastolic volume (EDV, ml), ventricular ejection time (ms), and thoracic fluid index (Ω) at peak exercise. Outcome variables were either proved CAD or patient sex. CAD was proved by angiography, stress scintigraphy, or stress echocardiogram. Results were compared using a Student's t test assuming equal variances, with significance considered at a P < 0.05, and 95% confidence intervals were calculated for significant results. Results Nine patients had proved CAD, 82 patients did not. Forty-three women and 48 men were included in the study. At peak exercise, patients with CAD had a significantly smaller increase in EDV than patients without CAD (32.8 ± 59.5 ml versus 89.3 ± 101.8 ml) without a significant change in CO, SV, or HR. At peak exercise, women had a significantly smaller increase in CO and SV without a significant change in HR. In addition, women had a significantly smaller increase in EDV. Conclusion When compared with patients without CAD, patients with CAD have a significantly smaller increase in EDV and a trend toward the same effect in CO and SV. Women have significantly smaller increases CO, SV, and EDV compared with men. Because there were no differences in HR, using HR as the sole end point would miss these differences. TEB is a practical means of measuring these variables.This content is limited to qualifying members.
Existing members, please login first
If you have an existing account please login now to access this article or view purchase options.
Purchase only this article ($25)
Create a free account, then purchase this article to download or access it online for 24 hours.
Purchase an SMJ online subscription ($75)
Create a free account, then purchase a subscription to get complete access to all articles for a full year.
Purchase a membership plan (fees vary)
Premium members can access all articles plus recieve many more benefits. View all membership plans and benefit packages.
References
1. Bernstein DP. Noninvasive cardiac output measurement, in Grenvik A, Ayres SM, Holbrook PR, Shoemaker WC (eds): Textbook of Critical Care. Philadelphia, W.B. Saunders Co., 1989, ed 2, pp 159–185.
2. Thangathurai D, Charbonnet C, Roessler P, Wo CC, Mikhail M, Yoahida R, et al. Continuous intraoperative noninvasive cardiac output monitoring using a new thoracic bioimpedance device. J Cardiothorac Vasc Anesth 1997; 11: 440–444.
3. Weiss S, Calloway E, Cairo J, Granger W, Winslow J. Comparison of cardiac output measurements by thermodilution and thoracic electrical bioimpedance in critically ill versus non-critically ill patients. Am J Emerg Med 1995; 13: 626–631.
4. Young JD, McQuillan P. Comparison of thoracic electrical bioimpedance and thermodilution for the measurement of cardiac index in patients with severe sepsis. Br J Anaesth 1993; 70: 58–62.
5. Nakatsuka M, MacLeod AD. Hemodynamic and respiratory effects of transtracheal high-frequency jet ventilation during difficult intubation. J Clin Anesth 1992; 4: 321–324.
6. Mattar JA, Shoemaker WC, Diament D, Lomar A, Lopes AC, De Freitas E, et al. Systolic and diastolic time intervals in the critically ill patient. Crit Care Med 1991; 19: 1382–1386.
7. Castor G, Molter G, Helms J, Niedermark I, Altmayer P. Determination of cardiac output during positive end-expiratory pressure: Noninvasive electrical bioimpedance compared with standard thermodilution. Crit Care Med 1990; 18: 544–546.
8. Gotshall RW, Wood VC, Miles DS. Modified head-up tilt test for orthostatic challenge of critically ill patients. Crit Care Med 1989; 17: 1156–1158.
9. Preiser JC, Daper A, Parquier JN, Contempre B, Vincent JL. Transthoracic electrical bioimpedance versus thermodilution technique for cardiac output measurement during mechanical ventilation. Intensive Care Med 1989; 15: 221–223.
10. Appel PL, Kram HB, Mackabee J, Fleming AW, Shoemaker WC. Comparison of measurements of cardiac output by bioimpedance and thermodilution in severely ill surgical patients. Crit Care Med 1986; 14: 933–935.
11. Scardo J, Kiser R, Dillon A, Brost B, Newman R. Hemodynamic comparison of mild and severe preeclampsia: Concept of stroke systemic vascular resistance index. J Matern Fetal Med 1996; 5: 268–272.
12. Scardo JA, Vermillion ST, Hogg BB, Newman RB. Hemodynamic effects of oral nifedipine in preeclamptic hypertensive emergencies. Am J Obstet Gynecol 1996; 175: 336–340.
13. van Oppen AC, van der Tweel I, Alsbach GP, Heethaar RM, Bruinse HW. A longitudinal study of maternal hemodynamics during normal pregnancy. Obstet Gynecol 1996; 88: 40–46.
14. Hobel CJ, Castro L, Rosen D, Greenspoon JS, Nessim S. The effect of thigh-length support stockings on the hemodynamic response to ambulation in pregnancy. Am J Obstet Gynecol 1996; 174: 1734–1741.
15. Ouzounian JG, Masaki DI, Abboud TK, Greenspoon JS. Systemic vascular resistance index determined by thoracic electrical bioimpedance predicts the risk for maternal hypotension during regional anesthesia for cesarean delivery. Am J Obstet Gynecol 1996; 174: 1019–1025.
16. Scardo JA, Hogg BB, Newman RB. Favorable hemodynamic effects of magnesium sulfate in preeclampsia. Am J Obstet Gynecol 1995; 173: 1249–1253.
17. van Oppen AC, van der Tweel I, Duvekot JJ, Bruinse HW. Use of cardiac index in pregnancy: Is it justified? Am J Obstet Gynecol 1995; 173: 923–928.
18. Heethaar RM, van Oppen AC, Ottenhoff FA, Brouwer FA, Bruinse HW. Thoracic electrical bioimpedance: Suitable for monitoring stroke volume during pregnancy? Eur J Obstet Gynecol Reprod Biol 1995; 58: 183–190.
19. Metry G, Wikstrom B, Linde T, Danielson BG. Gender and age differences in transthoracic bioimpedance. Acta Physiol Scand 1997; 161: 171–175.
20. van Oppen AC, van der Tweel I, Bruinse HW. Reproducibility of estimated cardiovascular function by transthoracic bioimpedance cardiography in healthy volunteers. Int J Biomed Comput 1994; 37: 15–18.
21. Moore R, Sansores R, Guimond V, Abboud R. Evaluation of cardiac output by thoracic electrical bioimpedance during exercise in normal subjects. Chest 1992; 102: 448–455.
22. Huang KC, Stoddard M, Tsueda KA, Heine MF, Thomas MH, White M, et al. Stroke volume measurements by electrical bioimpedance and echocardiography in healthy volunteers. Crit Care Med 1990; 18: 1274–1278.
23. Concu A, Scorcu M, Marcello C, Rocchitta A, Molari A, Esposito A, et al. Unchanging cardiac activity while increasing respiratory activity at the start of exercise in man: A beat-by-beat analysis by means of the impedance cardiography method. Cardiologia 1990; 35: 845–850.
24. Wong DH, O'Connor D, Tremper KK, Zaccari J, Thompson P, Hill D. Changes in cardiac output after acute blood loss and position change in man. Crit Care Med 1989; 17: 979–983.
25. Wong DH, Tremper KK, Zaccari J, Hajduczek J, Konchigeri HN, Hufstedler SM. Acute cardiovascular response to passive leg raising. Crit Care Med 1988; 16: 123–125.
26. Waluga M, Janusz M, Karpel E, Hartleb M, Nowak A. Cardiovascular effects of ephedrine, caffeine and yohimbine measured by thoracic electrical bioimpedance in obese women. Clin Physiol 1998; 18: 69–76.
27. Massidda B, Fenu MA, Ionta MT, Tronci M, Foddi MR, Montaldo C, et al. Early detection of the anthracycline-induced cardiotoxicity: A noninvasive haemodynamic study. Anticancer Res 1997; 17: 663–668.
28. Raine RA, Crayford TJ, Chan KL, Chambers JB. Gender differences in the treatment of patients with acute myocardial ischemia and infarction in England. Int J Technol Assess Health Care 1999; 15: 136–146.
29. Roger VL, Jacobsen SJ, Pellikka PA, Miller TD, Bailey KR, Gersh BJ. Gender differences in use of stress testing and coronary heart disease mortality: A population-based study in Olmsted County, Minnesota. J Am Coll Cardiol 1998; 32: 345–352.
30. Frishman WH, Gomberg-Maitland M, Hirsch H, Catanese J, Furia-Palazzo S, Mueller H, et al. Differences between male and female patients with regard to baseline demographics and clinical outcomes in the Asymptomatic Cardiac Ischemia Pilot (ACIP) Trial. Clin Cardiol 1998; 21: 184–190.
31. Kosmas CE, Mallozzi M, Moten M, Banka VS. Clinical symptomatology of coronary artery disease and results of exercise thallium scintigraphy: Gender-related differences. Indian Heart J 1997; 49: 497–501.
32. Travin MI, Duca MD, Kline GM, Herman SD, Demus DD, Heller GV. Relation of gender to physician use of test results and to the prognostic value of stress technetium 99m sestamibi myocardial single-photon emission computed tomography scintigraphy. Am Heart J 1997; 134: 73–82.
33. Lauer MS, Pashkow FJ, Snader CE, Harvey SA, Thomas JD, Marwick TH. Gender and referral for coronary angiography after treadmill thallium testing. Am J Cardiol 1996; 78: 278–283.
34. Merz CN, Moriel M, Rozanski A, Klein J, Berman DS. Gender-related differences in exercise ventricular function among healthy subjects and patients. Am Heart J 1996; 131: 704–709.
35. Bergelson BA, Tommaso CL. Gender differences in clinical evaluation and triage in coronary artery disease. Chest 1995; 108: 1510–1513.
36. Hachamovitch R, Berman DS, Kiat H, Bairey-Merz N, Cohen I, Cabico JA, et al. Gender-related differences in clinical management after exercise nuclear testing. J Am Coll Cardiol 1995; 26: 1457–1464.
37. Okin PM, Kligfield P. Gender-specific criteria and performance of the exercise electrocardiogram. Circulation 1995; 92: 1209–1216.
38. Cerqueira MD. Diagnostic testing strategies for coronary artery disease: Special issues related to gender. Am J Cardiol 1995; 75: 52D–60D.
39. Velmahos GC, Wo CC, Demetriades D, Bishop MH, Shoemaker WC. Invasive and noninvasive hemodynamic monitoring of patients with cerebrovascular accidents. West J Med 1998; 169: 17–22.
40. Weiss SJ, Kulik JP, Calloway E. Bioimpedance cardiac output measurements in patients with presumed congestive heart failure. Acad Emerg Med 1997; 4: 568–573.
41. Shoemaker WC, Belzberg H, Wo CC, Milzman DP, Pasquale MD, Baga L, et al. Multicenter study of noninvasive monitoring systems as alternatives to invasive monitoring of acutely ill emergency patients. Chest 1998; 114: 1643–1652.
42. Shoemaker WC, Wo CC, Demetriades D, Belzberg H, Asensio JA, Cornwell EE, et al. Early physiologic patterns in acute illness and accidents: Toward a concept of circulatory dysfunction and shock based on invasive and noninvasive hemodynamic monitoring. New Horiz 1996; 4: 395–412.
43. Bishop MH, Shoemaker WC, Shuleshko J, Wo CC. Noninvasive cardiac index monitoring in gunshot wound victims. Acad Emerg Med 1996; 3: 682–688.
44. Saunders CE. The use of transthoracic electrical bioimpedance in assessing thoracic fluid status in emergency department patients. Am J Emerg Med 1988; 6: 337–340.
45. Kirk JD, Turnipseed S, Lewis WR, Amsterdam EA. Evaluation of chest pain in low-risk patients presenting to the emergency department: The role of immediate exercise testing. Ann Emerg Med 1998; 32: 1–7.
46. Farkouh ME, Smars PA, Reeder GS, Zinsmeister AR, Evans RW, Meloy TD, et al. A clinical trial of a chest-pain observation unit for patients with unstable angina: Chest Pain Evaluation in the Emergency Room (CHEER) Investigators. N Engl J Med 1998; 339: 1882–1888.
47. Lewis WR, Amsterdam EA, Turnipseed S, Kirk JD. Immediate exercise testing of low risk patients with known coronary artery disease presenting to the emergency department with chest pain. J Am Coll Cardiol 1999; 33: 1843–1847.
48. Miles DS, Cox MH, Verde TJ, Gotshall RW. Application of impedance cardiography during exercise. Biol Psychol 1993; 36: 119–129.
49. Sheps DS, Petrovick ML, Kizakevich PN, Wolfe C, Craige E. Continuous noninvasive monitoring of left ventricular function during exercise by thoracic impedance cardiography-automated derivation of systolic time intervals. Am Heart J 1982; 103: 519–524.
50. Wilson MF, Sung BH, Pincomb GA, Lovallo WR. Simultaneous measurement of stroke volume by impedance cardiography and nuclear ventriculography: Comparisons at rest and exercise. Ann Biomed Eng 1989; 17: 475–482.
51. Denniston JC, Maher JT, Reeves JT, Cruz JC, Cymerman A, Grover RF. Measurement of cardiac output by electrical impedance at rest and during exercise. J Appl Physiol 1976; 40: 91–95.
52. Hanel B, Teunissen I, Rabol A, Warberg J, Secher NH. Restricted postexercise pulmonary diffusion capacity and central blood volume depletion. J Appl Physiol 1997; 83: 11–17.
53. Kim SY, Hinkamp TJ, Jacobs WR, Lichtenberg RC, Posniak H, Pifarre R. Effect of an inelastic aortic synthetic vascular graft on exercise hemodynamics. Ann Thorac Surg 1995; 59: 981–989.
54. Kizakevich PN, Teague SM, Nissman DB, Jochem WJ, Niclou R, Sharma MK. Comparative measures of systolic ejection during treadmill exercise by impedance cardiography and Doppler echocardiography. Biol Psychol 1993; 36: 51–61.
55. Smith JJ, Muzi M, Barney JA, Ceschi J, Hayes J, Ebert TJ. Impedance-derived cardiac indices in supine and upright exercise. Ann Biomed Eng 1989; 17: 507–515.
56. Balasubramanian V, Hoon RS. Changes in transthoracic electrical impedance during submaximal treadmill exercise in patients with ischemic heart disease: A preliminary report. Am Heart J 1976; 91: 43–49.
57. Seguro C, Sau F, Zedda N, Mura O, Montaldo C, Scano G, et al. Hemodynamic assessment at rest and during dynamic physical exercise in young subjects with and without hypertensive parents [in Italian]. Cardiologia 1995; 40: 391–397.
58. Smith JJ, Bush JE, Wiedmeier VT, Tristani FE. Application of impedance cardiography to study of postural stress. J Appl Physiol 1970; 29: 133–137.
59. Asensio JA, Demetriades D, Berne TV, Shoemaker WC. Invasive and noninvasive monitoring for early recognition and treatment of shock in high-risk trauma and surgical patients. Surg Clin North Am 1996; 76: 985–997.
60. Velmahos GC, Wo CC, Demetriades D, Shoemaker WC. Early continuous noninvasive haemodynamic monitoring after severe blunt trauma. Injury 1999; 30: 209–214.
