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Category: Cardiology

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

Although there is no obviously apparent physiologic reason for there to be a spontaneous cyclic variation of cardiac flow, it would seem unreasonable in the light of our inadequate understanding of the pathophysiology of Cheyne-Stokes respiration, to toally discount the cardiac events as being primary rather than secondary to the ventilatory cycle. Respiratory control is […]

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

Although 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 […]

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

Of these, a simply analyzed and consistent abnormality is the relationship of the peak velocity of the LV rapid filling phase (E peak) to that of the peak velocity occurring with the atrial contraction phase (A peak). With impairment of LV compliance, the peak velocity of rapid filling decreases (E peak) and the peak velocity […]

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

Mean transmitral velocity and peak early velocity are significantly higher at the end of hyperpnea as compared to the end of apnea. An increase in peak late transmitral filling velocity (A wave) occurs between these two phases. Consequently, the E/A ratio shows a significant decrease from end-hyperpnea to end-apnea (Fig 1). Similarly directed quantitative changes […]

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

Patients were examined in the supine or left lateral decubitus position using standard two-dimensional and pulsed Doppler echo-cardiographic techniques. Studies were recorded using commercially available echocardiographs and analyzed with a commercially available graphics analysis system. All studies were performed by one experienced echocardiographer. Left ventricular inflow velocity profiles were obtained from an apical four-chamber view […]

Doppler Evaluation of Changing Cardiac Dynamics during Cheyne-Stokes Respiration

Although Cheyne-Stokes respiration is a frequent and well-recognized accompaniment of severe cardiac failure and other conditions, the mechanism of the phenomenon of the periodic breathing is not well understood. In patients with congestive heart failure, it has been shown to be a marker of severe hemodynamic derangement. Cardiovascular changes and derangements occurring during Cheyne-Stokes have […]

Pretreatment with catecholamines can suppress severe ventricular arrhythmias in rats: DISCUSSION (part 4)

On the other hand, it has recently been demonstrated that catecholamines can enhance cell-to-cell mechanical and electrical coupling and attenuate conduction inhomogeneity and desynchronization of cells being a source of fibrillation during ischemia . This was based on the observation of catecholamine-induced increased spread of fluorescent dye between cardiomyocytes under hypoxic conditions and high calcium […]

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