DYSPNEA EVALUATION BY OXYGEN CONSUMPTION EXERCISE THALLIUM: MORE BANG FOR THE BUCK
Diane Wallis, MD; Keith Ende, MS; Vincent Bufalino, MD; Micheal O'Toole, MD
Symptoms of dyspnea, particularly in females, often leads to referral for exercise nuclear imaging. In the absence of an ischemic response, the etiology of dyspnea may remain elusive or prompt additional costly tests. Cardiopulmonary exercise testing (CPX) assesses both cardiac and pulmonary limitation to exercise. As pulmonary disorders may mimic cardiac symptoms, the value of adjunctive CPX with nuclear imaging was examined. A relational database of 90,000 private practice patients from September 1997 to April 2001 was queried. There were 11,076 thallium treadmills, of whom 52 had adjunctive CPX. CPX patients were 75% female, with a mean age of 60.5 +/- 14.3 years, and referred for dyspnea (59%), cardiac disease (31%) or chest pain (7%). Non-CPX thalliums during the same period were 32.6% female, with a mean age of 64.2 +/- 11.9 years, and referred for dyspnea (2.3%), cardiac disease (80.2%), or chest pain (17.5%). A pulmonary limitation to exercise, defined as oxygen desaturation of >4%, a breathing reserve of < 30%, or a fall in postexercise spirometry of 15% or more, was found in 28% of CPX-thallium tests, including 5% demonstrating exercise-induced bronchospasm. Resting spirometry was abnormal in 39%. An abnormal nuclear scan was found in only 22%. When divided by dyspnea symptoms (n = 31) or nondyspnea indications for exercise testing (n = 21), 35% of dyspnea patients had a pulmonary limitation to exercise, 58% had abnormal resting spirometry, and only 13% had an abnormal thallium. Even in patients with nondyspnea indications for nuclear treadmill testing, 19% had a pulmonary limitation to exercise, with 33% having abnormal spirometry and 33% having an abnormal thallium. Thus, CPX testing done in conjunction with thallium imaging may provide additional diagnostic information over nuclear treadmill testing alone, especially when dyspnea is part of the referring diagnosis.
RELATIONSHIP BETWEEN THE TALK TEST AND ISCHEMIC THRESHOLD
Carl Foster; Christina Cannon; John P. Porcari; Karen Skemp-Arlt; Dennis Fater; Mark Donahue; Jan Taggert; Richard Backes; University of Wisconsin-LaCrosse & Franciscan Skemp Healthcare-Mayo Medical System
The Talk Test (TT) has been shown to be associated with intensities within ACSM guidelines for exercise training, and very close to the intensity associated with the ventilatory threshold (VT). In view of the findings by Meyer et al (Eur Heart J 1995;16:623) that the VT often preceeds the ECG ischemic (ISCH) threshold, and evidence that untoward events during exercise training are associated with training intensities above the ISCH, it may be that the TT is an effective way to avoid myocardial ISCH during exercise training. We studied 19 patients with ST segment changes consistent with exertional myocardial ISCH during incremental exercise. We compared responses during exercise using the TT (POS = I can still speak comfortably; EQUIV = I'm not sure I can speak comfortably; NEG = I can't speak comfortably) versus minute-by-minute ECG responses, to define the first evidence of ISCH (see Table).
The responses during the EQUIV stage of the TT were very similar to those at ISCH. During the POS stage of the TT, all variables were significantly less than ISCH and 18 of 19 patients were below the HR, RPP and Ex Time of ISCH. Additionally, the HR at POS was approximately 10bpm below ISHC, which is a normal strategy for prescribing exercise when patients have ISCH. We conclude that when patients are able to speak comfortably, they are unlikely to have exertional ISCH.
COMPARISON OF METHODS OF USING THE TALK TEST FOR EXERCISE PRESCRIPTION
John P. Porcari; Amy J. Kelso; Carl Foster; Mark H. Gibson; Glenn Brice; Chris Dodge; Kristi Cadwell; Clinton A. Brawner; Steven J. Keteyian; University of Wisconsin-LaCrosse & Henry Ford Heart and Vascular Institute
The talk test (TT), or the highest intensity associated with comfortable speech, has been shown to be an effective method of prescribing exercise, capable of defining exercise intensities within ACSM guidelines for exercise prescription. Two primary strategies have been used with TT: recitation of a standard paragraph during incremental exercise (LAX), and responses to a tape-recorded interview during steady state exercise (DETROIT). In this study we sought to compare the heart rate (HR) and work rate (METs) responses to exercise derived from these two ways of using TT. Healthy volunteers (n = 20) performed two incremental exercise tests to define VT and the intensity associated with TT (LAX). They also performed a 12-minute free-range walk while responding to tape-recorded questions, with the instruction to keep the effort at a level that would just allow comfortable speech (DETROIT). During TT, the %HRR (78 +/- 9 vs 78 +/- 7) and % METs (77 +/- 6 vs 79 +/- 6) for LAX vs DETROIT, respectively, were not significantly different from each other and were within ACSM guidelines. The mean HR was not significantly different for LAX vs DETROIT (166 +/- 18 vs 165 +/- 13 bpm), and was not significantly different from the HR at VT (174 +/- 18 bpm). The work intensity was not significantly different for LAX vs DETROIT (9.7 +/- 0.9 vs 9.9 +/- 0.8 METs), and was not significantly different than METs at VT (10.6 +/- 0.9 METs). Both HR (r = 0.79) and METs (r = 0.65) were significantly correlated between LAX and DETROIT. We conclude that these different strategies for using the TT appear to result in a common exercise intensity that is very close to that associated with the VT. As such, the data support the generalizability of the TT as a method of prescribing exercise.
COMPARISON OF THE PERCENTAGE OF MAXIMAL HEART RATE AND HEART RATE RESERVE METHOD TO DETERMINE THE EXERCISE TARGET HEART RATE IN CORONARY HEART DISEASE PATIENTS TREATED WITH A BETA-BLOCKER
Monique H. Dufour*+; Pierre Boulay*; Denis Prud'homme++; *School of Kinesiology and Recreology, University of Moncton, Canada; +Division of Kinesiology, Laval University, Canada; ++School of Human Kinetics, University of Ottawa, Canada
To achieve the optimal benefits from an exercise program, it is usually recommended that coronary heart disease (CHD) patients exercise at an intensity between 40% to 85% of the heart rate reserve (HRR) or 55% to 90% of the maximal heart rate (maxHR). The purpose of this study was to investigate the variation in exercise target heart rate (THR) using the percentage of maxHR and the percentage of HRR methods in CHD patients treated with a beta-blocker. The corresponding exercise intensity used in this study was 60% to 80% of maxHR and 50% to 70% of HRR. Twenty-one CHD patients (8 women and 13 men) aged 59.9 +/- 8.9 years (mean +/- SD) who were part of a cardiac rehabilitation program participated in this study. There were 12 patients treated with metoprolol (87.5 +/- 37.7 mg twice daily) and 9 with atenolol (72.2 +/- 34.1 mg daily). All subjects underwent an indirect maximal exercise test (Bruce protocol) 2 to 3 hours after their morning medication intake. Resting heart rate was 57.8 +/- 8.6 bpm, maxHR was 112.2 +/- 18.3 bpm and exercise capacity was 8.6 +/- 1.9 METs. Exercise THR using the maxHR method was significantly lower (67.3 +/- 11.0 to 89.7 +/- 14.6 bpm) than HRR method (85.4 +/- 11.8 to 96.2 +/- 13.8 bpm;P < .001). Also, the change in heart rate to attain the lower limit of the exercise THR was significantly less with maxHR than the HRR method (9.5 +/- 9.8 vs 28.1 +/- 8.2 bpm;P < .001). Furthermore, at 60% of maxHR, the exercise THR was below or within 5 bpm of the resting heart rate in 48% of the patients. These results suggest that there is discrepancies between the percentage equivalent recommended to establish exercise THR using the percentage of HRR and maxHR method in CHD patients treated with a beta-blocker. Furthermore, the HRR should be considered the preferred method to determine the exercise THR in CHD patients treated with a beta-blocker.