The effect of minimally invasive surgical aortic valve replacement on postoperative pulmonary and skeletal muscle function.

Suboptimal post-operative improvements in functional capacity are often observed after minimally invasive aortic valve replacement (mini-AVR). It remains to be studied how AVR affects the cardiopulmonary and skeletal muscle function during exercise to explain these clinical observations and to provide a basis for improved/tailored post-operative rehabilitation. Twenty-two patients with severe aortic stenosis (AS) (aortic valve area (AVA) <1.0 cm²) were pre-operatively compared to 22 healthy controls during submaximal constant-workload endurance-type exercise for oxygen uptake ( V ̇ O 2 ), carbon dioxide output ( V ̇ C O 2 ), respiratory gas exchange ratio, expiratory volume ( V ̇ E ), ventilatory equivalents for O2 ( V ̇ E / V ̇ O 2 ) and CO2 ( V ̇ E / V ̇ C O 2 ), respiratory rate (RR), tidal volume (Vt ), heart rate (HR), oxygen pulse ( V ̇ O 2 /HR), blood lactate, Borg ratings of perceived exertion (RPE) and exercise-onset V ̇ O 2 kinetics. These exercise tests were repeated at 5 and 21 days after AVR surgery (n = 14), along with echocardiographic examinations. Respiratory exchange ratio and ventilatory equivalents ( V ̇ E / V ̇ O 2 and V ̇ E / V ̇ C O 2 ) were significantly elevated, V ̇ O 2 and V ̇ O 2 /HR were significantly lowered, and exercise-onset V ̇ O 2 kinetics were significantly slower in AS patients vs. healthy controls (P < 0.05). Although the AVA was restored by mini-AVR in AS patients, V ̇ E / V ̇ O 2 and V ̇ E / V ̇ C O 2 further worsened significantly within 5 days after surgery, accompanied by elevations in Borg RPE, V ̇ E and RR, and lowered Vt . At 21 days after mini-AVR, exercise-onset V ̇ O 2 kinetics further slowed significantly (P < 0.05). A decline in pulmonary function was observed early after mini-AVR surgery, which was followed by a decline in skeletal muscle function in the subsequent weeks of recovery. Therefore, a tailored rehabilitation programme should include training modalities for the respiratory and peripheral muscular system.