Biomedical subjects

J Ballen

Publications and source records attributed to J Ballen.

3 recordsLinked to original sources

PubMed1997

Factors affecting internal mammary artery graft survival: how is competitive flow from a patent native coronary vessel a risk factor?

Recent studies have suggested that competitive flow is an important factor in early internal mammary artery (IMA) graft failure. Flow competition from minimally diseased native coronary vessels has been implicated in the failure of IMA grafts, but does not seem to affect saphenous vein grafts (SVG). The objective of this study was to determine the effects of competitive flow on SVG and IMA grafts and to compare the patterns of flow dynamics and pressure on proximal and distal grafts to the left anterior descending (LAD) artery; factors that may be involved in graft failure. Twelve mongrel dogs underwent coronary artery bypass grafting using IMAs and a SVG to an open LAD artery. The right IMA (PIMA) and the SVG were anastomosed in the proximal LAD and the left IMA (DIMA) was anastomosed at a more distal location. The procedure was performed through a left thoracotomy, using an "off pump" technique. Graft flows were measured isolated and in competition. The IMAs and SVG provided flow levels similar to the native LAD when each one was the sole inflow to the LAD. During competitive flow conditions, total and diastolic SVG flows were reduced 54.4 and 50.5%, respectively (P < 0.05). Total and diastolic PIMA and DIMA flows were reduced more drastically (68.6-73.3 and 69.5-68.1%, respectively; P < 0.05). The DIMA had better preservation of diastolic flow compared to PIMA. A delay in the pressure wave was noted in the isolated IMAs, but not in the SVG. This pattern of flow disappeared during competition due to the large, systolic retrograde flow up the IMA grafts. In conclusion, IMAs compared to the SVG are longer and narrower conduits with lower levels of flow during competition. Low levels of flow and oscillating flow (retrograde/ antegrade) may be poorly tolerated by the IMA endothelium and may be factorial to graft failure. These data suggest that a more distal placement of the IMA graft may be protective to the arterial graft under competitive flow conditions.

Animals↗

PubMed1997

ITA versus SVG: a comparison of instantaneous pressure and flow dynamics during competitive flow.

OBJECTIVE: Competitive flow from patent native coronary vessels is implicated in the failure of internal thoracic artery (ITA) grafts, but it is not thought to affect saphenous vein graft (SVG) patency. This study examines instantaneous pressure and flow dynamics in left ITA and SVG grafts in competition with a patent left anterior descending (LAD) artery. METHODS: SVG (3.0-4.0 mm) and ITA (1.5-2.0 mm) to proximal LAD (2.5-3.0 mm) coronary bypass was performed in 10 mongrel dogs. Flow and pressure were measured in the occluded (No Competition) and opened (Competition) ITA, SVG and LAD. RESULTS: The ITA and SVG, when each was the sole inflow to the LAD, provided similar flow as the native LAD. During competitive flow, total LAD flow was preserved and flow in the ITA and SVG were reduced (8.20 +/- 1.25 and 10.00 +/- 1.73 ml/min; P < 0.005). SVG diastolic flow was reduced to 11.52 +/- 2.17 ml min (55.5%); P < 0.003. Flow in the SVG remained predominantly antegrade. In contrast, ITA diastolic flow was reduced more drastically, to 5.37 +/- 1.25 ml/min (80.7%); P < 0.0001. When the ITA was the only inflow to the LAD, there was delay in the LAD pressure wave. This delay disappears during competition due to the large, systolic retrograde flow up the ITA. CONCLUSION: The ITA, compared to the SVG, is a longer and narrower conduit with lower levels of flow during competition. Due to a delay in the pressure wave, the ITA flow is retrograde during early systole. Low levels of flow, with a markedly decreased diastolic phase, and the oscillating pattern in systole (retrograde/antegrade) may be poorly tolerated by the ITA endothelium and lead to graft deterioration.

Animals↗

PubMed1997

Variable effects of cardiomyoplasty on left ventricular function.

Cardiomyoplasty (CMP) has been considered as a possible treatment for patients with heart failure. Symptomatic improvements occur almost uniformly among survivors with CMP, but changes in left peak ventricular systolic pressure (PVSP) and stroke volume vary in patients. This study examined whether there is variability present shortly after cardiomyoplasty surgery. Cardiomyoplasty was performed in 11 mongrel dogs with normal ventricular function. Nine to twelve days after CMP, left ventricular (LV) function was evaluated by simultaneously measuring LV volume (conductance catheter) and pressure (Millar catheter). The latissimus dorsi muscle (LDM) was stimulated synchronously with ventricular systole in a ratio of 1:4 to 1:7 to avoid muscle fatigue. Data were analyzed on a beat by beat basis. The PVSP, and maximum dP/dt (+dP/dt) increased, but the absolute value of minimum dP/dt (-dP/dt) decreased in stimulated beats in 7 dogs while 4 dogs did not respond. The net changes in stimulated beats versus nonstimulated beats of PVSP were 6.1 +/- 1.8 mm Hg (4.3%), of stroke work was 4.5 +/- 1.9 gm x m (29.5%), of +dP/dt was 185 +/- 47 mm Hg/s (8%), and of -dP/dt was 168 +/- 43 mm Hg/s (7.8%) (p < 0.05) for all these net changes in the responding group while these variations were not significant in the nonresponding group. From the results of our study, active LDM assist improves left ventricular systolic function, occurring in only 7 of 11 experiments. This improvement is inconsistent and varied individually. The integrity of the LDM, tightness of wrapping, and adhesions might contribute to the variability which is present early after surgery and before the LDM is converted into a fatigue resistance muscle.

Animals↗