Cardiopulmonary exercise testing (CPET) is a methodology that has profoundly affected the approach to patients' functional evaluation, linking performance and physiological parameters to the underlying metabolic substratum and providing highly reproducible exercise capacity descriptors. This study provides professionals with an up-to-date review of the rationale sustaining the use of CPET for functional evaluation of cardiac patients in both the clinical and research settings, describing parameters obtainable either from ramp incremental or step constant-power CPET and illustrating the wealth of information obtainable through an experienced use of this powerful tool. The choice of parameters to be measured will depend on the specific goals of functional evaluation in the individual patient, namely, exercise tolerance assessment, training prescription, treatment efficacy evaluation, and/or investigation of exercise-induced adaptations of the oxygen transport/utilization system. The full potentialities of CPET in the clinical and research setting still remain largely underused and strong efforts are recommended to promote a more widespread use of CPET in the functional evaluation of cardiac patients.
Background-After mechanical heart valve replacement (MHVR), long-term use of unfractionated heparin is sometimes required because vitamin K antagonists (VKA) are temporarily contraindicated or because the time to reach the target international normalized ratio is long. The aim of this study was to investigate the feasibility of low-molecular-weight heparin treatment in these patients. Methods and Results-This work was conducted as a prospective study. We selected all patients (nϭ695) who underwent MHVR and were transferred to a postoperative cardiac rehabilitation center between January 2000 and January 2005. The study focused on patients who had not yet started VKA therapy or who had a below-target international normalized ratio despite VKA therapy. Unfractionated heparin was replaced by enoxaparin (100 IU/kg BID) until VKA treatment was fully effective. Two hundred fifty patients (60Ϯ11 years old) were enrolled 16Ϯ11 days after surgery (aortic valve replacement, nϭ190; mitral valve replacement, nϭ34; double valve replacement, nϭ26). Of these, 50% had permanent or transient atrial fibrillation, 40% had hypertension, 13% had diabetes, and 19% had a history of cardiac surgery. The mean duration of low-molecular-weight heparin treatment was 8.3Ϯ6.0 days. Patients were followed for 90 days, during which there were two major and three minor bleeding episodes and one transient ischemic attack. There were no cases of valve thrombosis and no deaths. Conclusions-After MHVR, one third of patients leave the cardiac surgery unit before VKA treatment is fully effective.Bridging anticoagulation therapy with enoxaparin appears to be feasible during this high-risk period for thromboembolism and could shorten the length of hospital stay. (Circulation. 2006;113:564-569.)
The Karvonen formula underestimates the heart rate at the anaerobic threshold in beta-blocked patients, which may lead to undertraining of patients with coronary artery disease; we propose another formula more adapted to these patients.
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