2 results
The pathogenesis of heart failure in infants with congenital heart disease
- Reiner Buchhorn, Annette Hammersen, Dietmar Bartmus, Joachim Bürsch
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- Journal:
- Cardiology in the Young / Volume 11 / Issue 5 / September 2001
- Published online by Cambridge University Press:
- 15 August 2006, pp. 498-504
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Background: The clinical symptoms of heart failure in infants with left-to-right shunts are thought to be explained by well-known hemodynamic disturbances such as pulmonary hypertension and overcirculation, but previous studies have not, thus far, found the expected correlations with hemodynamic and clinical parameters. Based on the neurohormonal model of heart failure, we hypothesised that the clinical symptoms of infants with left-to-right shunts are also related to neurohormonal disorders. Methods: We compared various neurohormonal and hemodynamic parameters measured invasively in 70 infants with left-to-right shunts to the respiratory rate and gain in weight over a corresponding period of time. Heart rate correlated significantly with respiratory rate (r = 0.62***, p < 0.001) and gain in weight (r =−0.31*, p = 0.015), but more conventional measures of severity, such as the ratio of pulmonary to systemic flows, failed to show comparable correlations with clinical symptoms. Respiratory rate was related to levels of norepinephrine (r = 0.47***, p < 0.001) and plasma renin activity (r = 0.65***, p < 0.001). The important impact of autonomic imbalance on respiratory rate was underlined by an analysis of variability of heart rate in 26 infants that showed significantly reduced values for the domains of time and frequency. We were not able to find a conclusive multiple regression model with which to explain the symptom "failure to thrive". Conclusions: A increased heart rate, reduced variability in heart rate, and elevated levels of norepinephrine and renin are significant predictors of clinical symptoms such as tachypnea in infants with congenital cardiac malformations. The neurohormonal hypothesis, in which heart failure is interpreted not only as a hemodynamic derangement but also as a neurohormonal disorder, may be valid for infants with congenital cardiac malformations.
Pathogenetic mechanisms of venous congestion after the Fontan procedure
- Reiner Buchhorn, Dietmar Bartmus, Wolfgang Buhre, Joachim Bürsch
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- Journal:
- Cardiology in the Young / Volume 11 / Issue 2 / March 2001
- Published online by Cambridge University Press:
- 15 August 2006, pp. 161-168
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Background: The hemodynamic status after a Fontan type procedure for definitive palliation of functionally univentricular hearts is dominated by a high central venous pressure, which seems to be one of several factors responsible for venous congestion appearing as a frequent complication in the early and late postoperative course. The purpose of our study was to find other hemodynamic parameters correlating with the presence of venous congestion and effusions in these patients. Methods: We compared the hemodynamic data of 18 patients who had an uneventful long-term course after a Fontan type procedure with the respective data of 10 patients who developed symptoms of venous congestion in the immediate postoperative period. Based on a theoretical model, we developed an algorithm to calculate mean hydrostatic capillary pressure from mean arterial pressure, systemic vascular resistance index and central venous pressure. Results: Pulmonary vascular resistance index (2.1 ± 1.0 mmHg L-1 min m2), mean left atrial pressure (9.7 ± 4.0 mmHg) and cardiac index (3.6 ± 0.6 1/min/m2) are mainly normal in patients with venous congestion in the immediate postoperative period, but mean hydrostatic capillary pressure is significantly higher compared to patients without venous congestion (24.3 ± 3.1 vs 18.3 ± 4.0 mmHg). Lower mean hydrostatic capillary pressures in these patients are due to a highly significant increase of systemic vascular resistance index (18.6 ± 4.2 versus 33.6 ± 6.6 mmHg L-1 min m2) and a concomitant decrease of cardiac index to 2.4 ± 0.3 1/min/m2. Conclusions: The increase of mean hydrostatic capillary pressure, caused by high central venous pressures but also by relatively low systemic vascular resistance indexes, seems to be the hemodynamic key parameter responsible for venous congestion and effusions in patients after a Fontan type procedure in the immediate postoperative period.