Physiologic mechanisms governing hemodynamic responses to positive inotropic therapy in patients with dilated cardiomyopathy.
Why the study?
Does dobutamine improve hemodynamic responses in patients with nonischemic dilated cardiomyopathy compared to normal subjects?
Population
13 patients with nonischemic dilated cardiomyopathy divided into 'appropriate' hypertrophy and 'inadequate'…
Comparison
Dobutamine infusion (beta-adrenoceptor agonist) vs Baseline conditions and age-matched normal…
Design
Cross-sectional
Authors
Discussion
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Implication
Dobutamine may increase afterload while blunting contractility in advanced nonischemic cardiomyopathy; leaves open hypertrophy-stratified response heterogeneity.
Key Points
- To determine the physiologic mechanisms and ventricular loading conditions that dictate variable hemodynamic responses to positive inotropic stimulation in dilated cardiomyopathy.
- Evaluated left ventricular geometry, loading conditions, and contractility using simultaneous high-fidelity pressure recordings and echocardiography in 13 patients with nonischemic dilated cardiomyopathy and 9 age-matched normal controls.
- Stratified patients by left ventricular end-diastolic wall thickness-to-dimension ratio into appropriate hypertrophy (n=5) and inadequate hypertrophy (n=8) groups, evaluating responses to dobutamine alongside afterload alteration via nitroprusside or methoxamine.
- Baseline left ventricular afterload (circumferential end-systolic wall stress) was elevated above normal by 168% in the appropriate hypertrophy group and 203% in the inadequate hypertrophy group.
- Dobutamine decreased left ventricular afterload by 12% in normal subjects and by 10% in appropriate hypertrophy, but augmented afterload by 5% in inadequate hypertrophy despite a 17% decline in systemic vascular resistance.
- Baseline contractile state was 61% of normal in appropriate hypertrophy and 44% in inadequate hypertrophy, with contractile responses to dobutamine reaching 52% and 22% of normal, respectively.
Structured PICO
Does dobutamine improve hemodynamic responses in patients with nonischemic dilated cardiomyopathy compared to normal subjects?
P
Population
13 patients with nonischemic dilated cardiomyopathy (DCM) divided into 'appropriate' hypertrophy (n=5, group 1) and 'inadequate' hypertrophy (n=8, group 2), and 9 age-matched normal subjects.
I
Intervention
Dobutamine infusion (beta-adrenoceptor agonist)
C
Comparator
Baseline conditions and age-matched normal subjects
O
Outcome
Hemodynamic responses including left ventricular afterload (circumferential end-systolic wall stress) and contractile statesurrogate
Positive inotropic therapy with dobutamine in patients with dilated cardiomyopathy is limited by an attenuated contractile response and elevated left ventricular afterload, particularly in those with inadequate hypertrophy.
Cite This Study
Borow et al. (1988) studied this question.