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  • Doppler Evaluation of Changing Cardiac Dynamics during Cheyne-Stokes Respiration: Outcome

Doppler Evaluation of Changing Cardiac Dynamics during Cheyne-Stokes Respiration: OutcomeAlthough an association of intracardiac with respiratory events is apparent, the initiation and chronologic sequence cannot be definitively established due to the recurrent cyclic, possibly self-perpetuating nature of the events. The mechanism of this series of events must, with our current state of knowledge, remain conjecture. Several factors may be responsible for the genesis of the intracardiac velocity changes seen during the varying phases of Cheyne-Stokes respiration. These include the following: first, changing arterial oxygen saturations during the cyclical phases of respiration. Left ventricular function may be adversely affected during periods of hypoxia. Paradoxically, the arterial oxygen saturations are lowest at the peak of hyperpnea and highest during apnea, suggesting that the saturations reflect the stimulus to, rather than the result of the different phases of ventilation. On this basis, left ventricular function could be expected to be most compromised during the hyperpneic phase. Thus, mechanisms other than, or in addition to, myocardial hypoxia appear to be operative. Second, the effect of varying right and left ventricular stroke volume with the respiration may be operative. Normally with inspiration right ventricular stroke volume increases and left ventricular stroke volume diminishes. Opposite effects occur with expiration. Perhaps the same factors which play a role in determining ventricular stroke volumes under physiologic conditions, ie, phase lag in respiratory variation of systemic venous return, inspiratory pooling of blood in the lungs or ventricular interdependence also serve to modify cardiac behavior in Cheyne-Stokes respiration. Third, changes in the cardiovascular system may be regulated by lung receptors, the exact nature and importance of which are not well defined. Link

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