Comparative feasibility of dobutamine stress echocardiography performed with and without intravenous contrast in patients with class III obesity.

BACKGROUND: Concern exists regarding adequacy of visualization of stress echocardiograms performed without intravenous contrast in persons with Class III obesity (body mass index ≥ 40 kg/m2 ). METHODS: Dobutamine stress echocardiography (DSE) was performed on 128 candidates for bariatric surgery with class III obesity without chest pain or pre-existent coronary artery disease (CAD). DSE without intravenous contrast was initially performed on 62 patients with class III obesity, then was subsequently was performed with intravenous contrast on 66 patients with class III obesity. Left ventricular (LV) regional wall motion was assessed at baseline and peak stress using the 16-segment model. RESULTS: In the intravenous contrast group, 1046 of 1056 LV segments studied (99.1%) were well-visualized and interpretable at baseline and 1044 of 1056 LV segments studied (98.9%) were well-visualized and interpretable at peak stress. In the non-contrast group, 905 of 992 segments studied (91.2%) were well-visualized and interpretable at baseline and 886 of 992 segments studied (89.3%) were well-visualized and interpretable at peak stress. A significantly greater number of LV segments were well-visualized and interpretable in the intravenous contrast group than in the group compared to the non-contrast group, at baseline and at peak stress (p < 0.00001 for both). DSE was positive for ischemia in one patient. All patients underwent bariatric surgery without cardiovascular complications. Six months after surgery, all patients were alive; none developed cardiovascular events. CONCLUSION: The use of intravenous contrast during DSE significantly improves visualization and interpretability of LV segments in patients with class III obesity.

Pulmonary hemodynamic response to acute combination and monotherapy with sildenafil and brain natriuretic peptide in rats with monocrotaline-induced pulmonary hypertension.

BACKGROUND: The lungs of patients with pulmonary arterial hypertension (PAH) exhibit decreased bioavailability of nitric oxide and downstream signaling through cyclic guanosine monophosphate (cGMP). Therapies that enhance cGMP-mediated vasodilation have shown efficacy in treating PAH. We tested the hypothesis that combination therapy with sildenafil, a cGMP phosphodiesterase type 5 inhibitor, and brain natriuretic peptide (BNP), a receptor-mediated guanosine cyclase stimulator, synergistically attenuates monocrotaline-induced PAH in rats compared with either monotherapy. METHODS: Adult male Sprague-Dawley rats were subcutaneously injected with monocrotaline (n = 41, 50 mg/kg). After approximately 4 weeks, the rats were infused intravenously with vehicle solution, sildenafil (42 and 85 microg/kg/min), or BNP (50 and 100 ng/kg/min), alone and in varied combination. The primary endpoint was the relative change in right ventricular systolic pressure (RVSP) and mean arterial systemic pressure (MAP). Secondary endpoints included heart rate and dP/dt. RESULTS: Vehicle infusions did not alter hemodynamic variables. Sildenafil85 (85 microg/kg/min) alone decreased RVSP (-16.6 +/- 5.6%) and decreased MAP (-4.0 +/- 4.7%). BNP50 (50 ng/kg/min) and BNP100 (100 ng/kg/min) decreased RVSP (-23.3 +/- 5.7% and -27.1 +/- 2.9%, respectively) and MAP (-6.4 +/- 5.8% and -14.3 +/- 4.1%, respectively). Combination therapy with sildenafil42 and BNP50 decreased RVSP (-20.7 +/- 5.6%) and showed a lessened systemic effect (MAP = -11.6 +/- 5.9%). Combination therapy with sildenafil85 and BNP100 decreased RVSP (-27.6 +/- 3.2%, P = NS) and showed increased systemic effect (MAP = -20.7 +/- 3.1%, P < 0.05) in comparison with sildenafil85. CONCLUSIONS: This study suggests that intravenous administration of both sildenafil and BNP monotherapy produces significant improvement in RVSP, making them potentially viable options for the treatment of PAH, whereas combination therapy produces no additional improvement in pulmonary hemodynamics.