Effects of impaired lung function and pulmonary regurgitation on maximal exercise capacity in patients with repaired tetralogy of Fallot

Abstract

Long-term haemodynamic results and exercise capacity were studied in 34 patients with tetralogy of Fallot (24 men and 10 women) repaired 10.0 +/- 4.9 (mean +/- SD) years previously and compared to 34 healthy matched controls. All subjects were studied by resting spirometry, echocardiography and a symptom limited treadmill exercise test (modified Bruce protocol). The maximal oxygen consumption was 38.2 +/- 8.0 ml.kg-1.min-1 in patients and 48.1 +/- 8.1 ml.kg-1.min-1 in the control group (P < 0.001). Reduced maximal oxygen consumption was found in patients with low vital capacity (VC) and pulmonary regurgitation (PR). The ventilatory anaerobic threshold (VAT) was 23.8 +/- 0.6 ml.kg-1.min-1 and 29.9 +/- 0.6 ml.kg-1.min-1 in patients and controls, respectively (P < 0.001). VC was 3.4 +/- 1.21 in patients and 4.0 +/- 1.31 in controls (P < 0.02). In the patients, maximal ventilation was reduced and at submaximal exercise, the breathing frequency increased. Heart rates during exercise were similar in patients and controls. Tricuspid regurgitation (TR) was detected in 20 patients (58.8%); however, the exercise capacity was not reduced. Thus, impaired exercise capacity in tetralogy of Fallot is partly due to reduced resting lung function, pulmonary regurgitation and low ventilatory anaerobic threshold.

The BNP concentrations and exercise capacity assessment with cardiopulmonary stress test in patients after surgical repair of Fallot's tetralogy

“…Diaphragmatic palsy after the surgery and respiratory muscle weakness may also contribute to the observed impairment [27]. Reduced lung capacity may also result from hypoplasia of lung arterioles, and reduced number of alveoli, both of which are associated with diminished pulmonary blood flow [28,35]. Recent studies suggest that increased serum BNP levels are useful in early diagnosis of asymptomatic heart failure [11,12].…”

Timing and type of surgery for severe pulmonary regurgitation after repair of tetralogy of Fallot

“…A decrease in PR and an abnormal RV response to exercise in patients with rTOF has also been described [33]. Other important contributors to exercise intolerance are lung dysfunction [34] and chronotropic incompetence [26] probably due to abnormal autonomic reflexes [35,36].…”

Exercise Studies in Tetralogy of Fallot: A Review

“…This was also true in all studies with normal controls (Table 2). Since few submaximal data have been reported [2,9,27,47,58,69,80], we analyzed unpublished data of 39 tetralogy patients who were maximally exercised on the treadmill using the Bruce protocol. Comparison of heart rates at rest and at each stage and at maximal effort with the predicted normal data of Cumming [11] showed normal resting, but significantly reduced submaximal and maximal exercise heart rates in the tetralogy patients.…”