The dicrotic pulse: a common, non-ominous finding after the Ross operation.

We noted a dicrotic pulse in several patients following a Ross operation. Although the etiology of this unique arterial waveform is not completely understood, it has been reported as a sign of low cardiac output and a poor prognosis. We reviewed preoperative echocardiograms and postoperative radial arterial pressure tracings in 33 patients who underwent a Ross procedure between 2000 and 2004. We found a dicrotic pulse to occur commonly (20/33; 61%) following a Ross operation. Moderate to severe preoperative aortic insufficiency was present in 19/20 patients (95%) in whom a dicrotic pulse was noted and in only 3/13 (23%) who did not exhibit a postoperative dicrotic pulse (p<0.001). A dicrotic pulse was not associated with an increased use of vasoactive infusions or longer hospitalization following the Ross operation. The dicrotic pulse should be recognized as a common postoperative finding in Ross patients that does not herald a delayed postoperative convalescence. The mechanism for a dicrotic pulse in these patients is speculative but may result from changes in vascular compliance secondary to chronic aortic insufficiency.

Uncoupling and recoupling of autonomic regulation of the heart beat in pediatric septic shock.

Healthy physiological systems exhibit marked signal variability and complexity, whereas diseased systems generally show a loss of variability, decreased complexity ("decomplexification"), and increased regularity. The goal of this study was to evaluate the uncoupling and recoupling phenomenon in children with septic shock by observing serial changes in heart rate variability metrics. Data were collected from 7 children with septic shock by using the computer system in the Complex Systems Laboratory at Oregon Health Sciences University. Heart rate time series were constructed and analyzed by using the Hales Research System at intervals of 6 h during pediatric intensive care unit (PICU) hospitalization. These power spectral values were then plotted vs. time. Six of seven patients showed an increase over time in low-frequency heart rate power and the low-/high-frequency ratio, whereas high-frequency heart rate power decreased. We also compared the change in mean heart rate, heart rate standard deviation, and power spectral values during the first 24 h of PICU hospitalization vs. the remainder of the PICU stay (for the 5 patients with a PICU length of stay > 48 h). Compared to the initial 24 h in the PICU, low-frequency power and the low-/high-frequency ratio increased, whereas high-frequency power decreased over the course of the illness. This report shows the potential value of monitoring the uncoupling and recoupling phenomenon in patients with septic shock. Our results are in agreement with other investigators who report evidence of decomplexification both in experimental models of sepsis and in clinical studies and provide direction for further work.