Left Ventricular Mechanics and Myocardial Blood Flow Following Restoration of Normal Activation Sequence in Paced Patients With Long-term Right Ventricular Apical Stimulation

CHEST Journal ◽  
2003 ◽  
Vol 124 (1) ◽  
pp. 233-241 ◽  
Author(s):  
Emmanuel N. Simantirakis ◽  
George E. Kochiadakis ◽  
Konstantinos E. Vardakis ◽  
Nikolaos E. Igoumenidis ◽  
Stavros I. Chrysostomakis ◽  
...  
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Right Ventricular ◽  
Left Ventricular ◽  
Ventricular Mechanics ◽  
Left Ventricular Mechanics ◽  
Activation Sequence

Regional myocardial blood flow and oxygen delivery in fetal, newborn, and adult sheep

1982 ◽  
Vol 243 (5) ◽  
pp. H729-H731 ◽  
Author(s):  
D. J. Fisher ◽  
M. A. Heymann ◽  
A. M. Rudolph
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Right Ventricular ◽  
Oxygen Delivery ◽  
Left Ventricular ◽  
Ventricular Free Wall ◽  
Regional Myocardial Blood Flow ◽  
Free Wall ◽  
Right Ventricular Free Wall ◽  
The Right

We measured and calculated their product, regional myocardial oxygen delivery, in unanesthetized, previously instrumented fetal, newborn, and adult sheep. In the fetus, blood flow and oxygen delivery were greater to the right ventricular free wall than to the left ventricular free wall. In the left ventricular free wall oxygen delivery increased significantly after birth and later decreased to a level in the adult that was similar to that of the fetus. There was a progressive decrease in oxygen delivery to the right ventricular free wall during the developmental period that we studied. Although the inner-to-outer blood flow ratio was significantly lower for the left and right ventricular free walls of the fetuses as compared with the newborns and adults, the ratio was greater than one in all three groups for both of the ventricular free walls. These data demonstrate that the changes that occur in the circulation after birth are associated with significant alterations in right and left ventricular myocardial blood flow and oxygen delivery, which most likely reflect changes in regional myocardial metabolic demands. In addition, there are further significant changes in regional myocardial blood flow during the transition from the newborn to adult hemodynamics.

Regional myocardial blood flow during pericardial tamponade

1984 ◽  
Vol 62 (5) ◽  
pp. 539-543 ◽  
Author(s):  
Gerald C. Taichman ◽  
Paul Byrne ◽  
George V. Forester ◽  
Wilbert J. Keon
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Right Ventricular ◽  
Ventricular Volume ◽  
Pericardial Tamponade ◽  
Left Ventricular ◽  
Regional Myocardial Blood Flow ◽  
Pericardial Cavity ◽  
Blood Flows ◽  
Regional Myocardial Blood

The relative changes in myocardial blood flows within different parts of the heart were measured in anaesthetized thoracotomized dogs during and following effusive pericardial tamponade. Blood flows measured in a group of animals bled to the same arterial hypotensive levels served as experimental controls. The results demonstrate that regional myocardial blood flows to all areas were severely reduced during tamponade. Regional differences in the relative responses were evident; right and left atrial flows decreased more than left ventricular or septal flows which in turn decreased more than right ventricular flow. Significant changes in transmural flow distributions were seen as well; on a relative basis, left and right ventricular endocardial flows decreased more than epicardial and the flow within the left side of the septal wall decreased more than the right. Although decreases in aortic pressure and ventricular volumes can account for some of these changes in flow seen in tamponade, alterations in extravascular compression appear to further reduce the myocardial perfusion and may be responsible for the differences in regional responses. In further experiments when the pericardial cavity was drained following 2 h of tamponade, a hyperemic response was seen throughout the heart indicating that the myocardial flow during tamponade may-have been insufficient to meet the cardiac demands. In conclusion tamponade appears to result in a disproportionate decrease in myocardial blood flow to various parts of the heart which cannot be explained on the basis of a decrease in blood pressure or a reduction in ventricular volume.

scholarly journals Myocardial vascular and metabolic adaptations in chronically anemic fetal sheep

2005 ◽  
Vol 289 (6) ◽  
pp. R1736-R1745 ◽  
Author(s):  
Christopher E. Mascio ◽  
Aaron K. Olison ◽  
J. Carter Ralphe ◽  
Robert J. Tomanek ◽  
Thomas D. Scholz ◽  
...  
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Right Ventricular ◽  
Left Ventricular ◽  
Glycolytic Enzymes ◽  
Vegf Receptor ◽  
Mrna Levels ◽  
Fetal Anemia ◽  
Fetal Sheep ◽  
Metabolic Adaptations

Little is known about the vascular and metabolic adaptations that take place in the fetal heart to maintain cardiac function in response to increased load. Chronic fetal anemia has previously been shown to result in increased ventricular mass, increased myocardial vascularization, and increased myocardial expression of hypoxia-inducible factor-1 (HIF-1) and vascular endothelial growth factor (VEGF). We therefore sought to determine whether chronic fetal anemia induces expression of HIF-1-regulated angiogenic factors and glycolytic enzymes in the fetal myocardium. Anemia was produced in chronically instrumented fetal sheep by daily isovolemic hemorrhage (80–100 ml) for either 3 ( n = 4) or 7 days ( n = 11) beginning at 134 days of gestation (term 145 days). Catheterized, nonbled twins served as controls. Isovolemic hemorrhage over 7 days resulted in decreased fetal hematocrit (37 ± 1 to 20 ± 1%) and arterial oxygen content (6.5 ± 0.4 to 2.8 ± 0.2 ml O2/dl). Myocardial blood flow and vascularization were significantly increased after 7 days of anemia. Myocardial HIF-1 protein expression and VEGF (left ventricular), VEGF receptor-1 (right ventricular), and VEGF receptor-2 (right ventricular, left ventricular) mRNA levels were elevated ( P < 0.05) in 7-day anemic compared with control animals. Myocardial expressions of the glycolytic enzymes aldolase, lactate dehydrogenase A, phosphofructokinase (liver), and phosphoglycerol kinase were also significantly elevated after 7 days of anemia. Despite the absence of a significant increase in myocardial HIF-1α protein in 3-day anemic fetuses, expressions of VEGF, VEGF receptor-1, and the glycolytic enzymes were greater in 3-day compared with 7-day anemic animals. These data suggest that HIF-1 likely participates in the fetal myocardial response to anemia by coordinating an increase in gene expressions that promote capillary growth and anaerobic metabolism. However, factors other than HIF-1 also appear important in the regulation of these genes. We speculate that the return of mRNA levels of angiogenic and glycolytic enzymes toward control levels in the 7-day anemic fetus is explained by a significantly increased resting myocardial blood flow, resulting from coronary vascular growth and increased coronary conductance, and a return to a state of adequate oxygen and nutrient delivery, obviating the need for enhanced transcription of genes encoding angiogenic and glycolytic enzymes.

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