Abstract
Increased ventilation relative to metabolic secondary to alveolar hyperventilation and/or increased physiological dead space (excess ventilation) is a key cause of exertional dyspnoea. Excess ventilation has assumed a prominent role in the functional assessment of patients with heart failure (HF) with reduced (r) or preserved (p) ejection fraction, pulmonary arterial hypertension (PAH), and chronic thromboembolic PH (CTEPH). We herein provide the key pieces of information to the caring physician to a) gain unique insights into the seeds of patients’ shortness of breath, and b) develop a rationale for therapeutically lessening excess ventilation to mitigate this distressing symptom. Reduced bulk O2 transfer induced by cardiac output limitation and/or right ventricle-pulmonary arterial uncoupling increase neurochemical afferent stimulation and (largely chemo-) receptor sensitivity, leading to alveolar hyperventilation in HFrEF, PAH and in small-vessel, distal CTEPH. As such, interventions geared to improve central hemodynamics and/or reduce chemosensitivity have been particularly effective in lessening their excess ventilation. In contrast, high filling pressures in HFpEF (a) and impaired lung perfusion leading to ventilation/perfusion mismatch in proximal CTEPH (b) conspire to increase physiological dead space. Accordingly, decreasing pulmonary capillary pressures (a) and mechanically unclogging larger pulmonary vessels (pulmonary endarterectomy and balloon pulmonary angioplasty) (b) have been associated with larger decrements in excess ventilation. Exercise training has a strong beneficial effect across diseases. Addressing some major unanswered questions on the link of excess ventilation with exertional dyspnoea under the modulating influence of pharmacological and non-pharmacological interventions might prove instrumental to alleviate the devastating consequences of these prevalent diseases.
Footnotes
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- Received January 20, 2022.
- Accepted May 5, 2022.
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