Summary
The surgical creation of a supravalvular pulmonary Stenosis (PS) adequate to prepare
the left ventricle (LV) for anatomic correction in cases of simple transposition of
the great arteries (TGA) is difficult.
To gain more information on the hemodynamic changes immediately following PS of various
degrees, pressures (P) in the right atrium (RA), right ventricle (RV), pulmonary artery
(PA) and left ventricle (LV) as well as pulmonary flow (F) were monitored 40 minutes
(30 to 50 minutes after PS (n = 15) in 10 open chested pigs (mean weight: 20.7 kg).
Hemodynamic changes can be separated into an adaptation phase (AP) with an “overshoot”
response of most hemodynamic Parameters and a stable phase (SP) without further changes,
reached after 6.5 minutes (1 to 18 minutes). This pattern was independent of the degree
of PS (increase of RV Pmax: 13 to 39 mmHg). Maximal changes (p<0.01) during AP included:
RV Pmax: +25 ± 9 mmHg, RV EDP: +6 ± 3 mmHg, RV dp/dt max: +315 ± 208 mmHg/sec, LV
Pmax: -43 ± 24 mmHg, PA max. syst, flow: -0.3 ±0.15 ml/sec, CO: -0.45 ± 0.3 l/min.
During SP, LV Pmax and PA Pmean werp normal. RV EDP and RA Pmean had decreased (p
< 0.01) but remained elevated as compared to the control values (p < 0.01)., The right
ventricular maximal pressure had decreased 30% but remained elevated compared to control
values (p<0.01). A change of RV Pmax during SP correlated (r = 0.93) with the maximal
change of RV Pmax during AP.
A final evaluation of the degree of PS is only possible after an average period of
6.5 minutes. It is dependent on its maximal change during AP. During AP, significant
reduction of flow and systematic pressure can be anticipated. An acute pressure load
of RV up to 100% is associated with a significant increase of RV EDP and RA Pmean
as well as a decrease of maximal systolic pulmonary flow.
Key words
Pulmonary artery banding - Right ventricular pressure loading - Right ventricular
function - Transposition of the great arteries
