Cardiac function in fetal sheep during two weeks of hypoxemia

1994 ◽  
Vol 266 (6) ◽  
pp. R1778-R1785 ◽  
Author(s):  
M. Kamitomo ◽  
L. D. Longo ◽  
R. D. Gilbert
Keyword(s):  
Arterial Pressure ◽  
Cardiac Function ◽  
Ventricular Function ◽  
Left Ventricular ◽  
Pressure Sensitivity ◽  
Sensitivity Curve ◽  
Fetal Sheep ◽  
Cardiac Responses ◽  
Ovine Fetal

Although several studies have examined fetal cardiac responses to acute hypoxemia, relatively little is known of the response to prolonged hypoxemia. To determine the effects of long-term hypoxemia on ovine fetal cardiac function, we measured right (QRV) and left ventricular outputs (QLV) and determined the effects of increasing preload (ventricular function curve) and afterload (arterial pressure sensitivity curve) on the left ventricle. Six days after fetal surgical instrumentation with catheters and electromagnetic flow probes (approximately 123 days gestation), we administered N2 into the maternal trachea for 14 days to reduce maternal PO2 to approximately 55 Torr (hypoxemic group, Hyp, n = 6). Normoxic animals were used as controls (Cont, n = 6). With the onset of hypoxemia, fetal arterial PO2 was reduced from approximately 27 to approximately 18 Torr. Fetal heart rate in Hyp fetuses decreased approximately 22% on day 14 compared with Cont (P < 0.05). Mean arterial pressure in the Hyp group was higher than that of Cont but not significantly so. Right and left atrial pressures were not affected by hypoxemia. QRV in Hyp fetuses was maintained on day 1 but decreased significantly by day 3 (approximately 19%) and further decreased on days 7 (approximately 28%) and 14 (approximately 34%). QLV was not depressed until day 7 (approximately 20%), with a further decrease on day 14 (approximately 38%). In association with the decreased QLV the plateau of the ventricular function curve in Hyp fetuses was depressed significantly on days 7 and 14. In contrast, the slope of the arterial pressure sensitivity curve in the Hyp group did not differ from Cont.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac function during long-term hypoxemia in fetal sheep

1989 ◽  
Vol 257 (2) ◽  
pp. H581-H589 ◽  
Author(s):  
J. G. Alonso ◽  
T. Okai ◽  
L. D. Longo ◽  
R. D. Gilbert
Keyword(s):  
Arterial Pressure ◽  
Cardiac Function ◽  
Right Ventricular ◽  
Ventricular Function ◽  
Right Ventricular Function ◽  
Hemoglobin Concentration ◽  
Fetal Sheep ◽  
Intravascular Catheters ◽  
Arterial Po2

To examine right ventricular function during long-term hypoxemia, we instrumented 12 fetal sheep with intravascular catheters and an electromagnetic flow probe on the pulmonary artery. In six cases, hypoxemia was induced by infusing N2 gas into the maternal trachea for 2 wk. Maternal arterial PO2 was less than 60 Torr, and fetal arterial PO2 was reduced from approximately 26 to approximately 19 Torr. Six cases served as nonhypoxic controls. We studied fetal cardiac function by increasing either preload with a volume infusion of 5% (wt/vol) dextrose or afterload by administering methoxamine (alpha-adrenergic agonist). In hypoxic animals, right ventricular output (QRV) and stroke volume (SV) were not affected on the first 2 days but fell 30% on day 3. Fetal arterial pressure (Pfa) increased 20%, hemoglobin concentration increased approximately 30%, and fetal heart rate (FHR) showed minimal changes. Within 2 wk, QRV recovered to normal values, whereas ventricular sensitivity to arterial pressure was reduced. We observed no change in plasma concentration of "cardiac enzymes" or differences in fetal growth between groups. In conclusion, during prolonged hypoxemia, right ventricular function showed a triphasic response (primary maintenance, secondary depression, and subsequent recovery), achieving a new steady state 2 wk after the start of hypoxia, characterized by decreased sensitivity to afterload, associated with polycythemia and hypertension.

scholarly journals Attenuated muscle metaboreflex-induced increases in cardiac function in hypertension

2013 ◽  
Vol 305 (10) ◽  
pp. H1548-H1554 ◽  
Author(s):  
Javier A. Sala-Mercado ◽  
Marty D. Spranger ◽  
Rania Abu-Hamdah ◽  
Jasdeep Kaur ◽  
Matthew Coutsos ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Cardiac Function ◽  
Peripheral Resistance ◽  
Artery Occlusion ◽  
Left Ventricular ◽  
Exercise Intolerance ◽  
Muscle Metaboreflex ◽  
Cardiac Responses

Sympathoactivation may be excessive during exercise in subjects with hypertension, leading to increased susceptibility to adverse cardiovascular events, including arrhythmias, infarction, stroke, and sudden cardiac death. The muscle metaboreflex is a powerful cardiovascular reflex capable of eliciting marked increases in sympathetic activity during exercise. We used conscious, chronically instrumented dogs trained to run on a motor-driven treadmill to investigate the effects of hypertension on the mechanisms of the muscle metaboreflex. Experiments were performed before and 30.9 ± 4.2 days after induction of hypertension, which was induced via partial, unilateral renal artery occlusion. After induction of hypertension, resting mean arterial pressure was significantly elevated from 98.2 ± 2.6 to 141.9 ± 7.4 mmHg. The hypertension was caused by elevated total peripheral resistance. Although cardiac output was not significantly different at rest or during exercise after induction of hypertension, the rise in cardiac output with muscle metaboreflex activation was significantly reduced in hypertension. Metaboreflex-induced increases in left ventricular function were also depressed. These attenuated cardiac responses caused a smaller metaboreflex-induced rise in mean arterial pressure. We conclude that the ability of the muscle metaboreflex to elicit increases in cardiac function is impaired in hypertension, which may contribute to exercise intolerance.

Right and left ventricular function in fetal sheep exposed to long-term high-altitude hypoxemia

1992 ◽  
Vol 262 (2) ◽  
pp. H399-H405 ◽  
Author(s):  
M. Kamitomo ◽  
L. D. Longo ◽  
R. D. Gilbert
Keyword(s):  
High Altitude ◽  
Ventricular Function ◽  
Fetal Heart ◽  
Left Ventricular ◽  
Minimal Change ◽  
Fetal Sheep ◽  
Fetal Cardiac Function ◽  
The Right ◽  
Arterial Po2

To test the hypothesis that long-term hypoxemia affects fetal cardiac function, we measured right (RVO) and left (LVO) ventricular output by electromagnetic flow probes. We also determined their responses to increased preload (ventricular function curve, VFC) and afterload (arterial sensitivity curve, ASC). We exposed seven pregnant ewes to high altitude (3,820 m) from 30 to 120 days gestation, at which time surgery was performed. Thereafter, maternal arterial PO2 was maintained at approximately 60 Torr by N2 administration. Fetal arterial PO2 was significantly reduced in the hypoxemic fetuses (Hyp, n = 7) compared with that of control (Con, n = 9) (19.3 +/- 0.8 vs. 23.3 +/- 0.5 Torr, P less than 0.01). Mean arterial pressures in the Hyp group were elevated (52.0 +/- 1.2 vs. 44.4 +/- 1.7 mmHg, P less than 0.01) and fetal heart rate showed minimal change. Catecholamine concentrations in the Hyp group tended to be higher than the Con group, but not significantly so. For Con and Hyp, RVO equaled 275.7 +/- 9.1 vs. 183.1 +/- 10.1 (P less than 0.01), LVO equaled 165.7 +/- 16.9 vs. 141.6 +/- 16.5 (NS), and combined ventricular output (CVO) equaled 441.1 +/- 22.9 vs. 334.9 +/- 28.3 ml.min-1.kg-1 (P less than 0.05). For the LV there were no significant differences of the VFC between the Con and Hyp groups. However, the right VFC in the Hyp was significantly shifted downward. Concerning afterload, in the RV the slope of the ASC of Con was steeper than that of Hyp (-3.00 +/- 0.05 vs. -0.84 +/- 0.11 ml.ml.min-1.g-1.mmHg-1, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Impact of left ventricular function on immediate and long-term outcomes after pericardiectomy in constrictive pericarditis

2008 ◽  
Vol 136 (5) ◽  
pp. 1136-1141 ◽  
Author(s):  
Jong-Won Ha ◽  
Jae K. Oh ◽  
Hartzell V. Schaff ◽  
Lieng H. Ling ◽  
Stuart T. Higano ◽  
...  
Keyword(s):  
Left Ventricular Function ◽  
Ventricular Function ◽  
Constrictive Pericarditis ◽  
Left Ventricular ◽  
Long Term Outcomes

Long-term levosimendan treatment improves systolic function and myocardial relaxation in mice with cardiomyocyte-specific disruption of the Serca2 gene

2013 ◽  
Vol 115 (10) ◽  
pp. 1572-1580 ◽  
Author(s):  
Vigdis Hillestad ◽  
Frank Kramer ◽  
Stefan Golz ◽  
Andreas Knorr ◽  
Kristin B. Andersson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heart Failure ◽  
Cardiac Function ◽  
Diastolic Dysfunction ◽  
Systolic Function ◽  
Cytosolic Calcium ◽  
Left Ventricular ◽  
Pressure Measurements ◽  
Human Heart Failure

In human heart failure (HF), reduced cardiac function has, at least partly, been ascribed to altered calcium homeostasis in cardiomyocytes. The effects of the calcium sensitizer levosimendan on diastolic dysfunction caused by reduced removal of calcium from cytosol in early diastole are not well known. In this study, we investigated the effect of long-term levosimendan treatment in a murine model of HF where the sarco(endo)plasmatic reticulum ATPase ( Serca) gene is specifically disrupted in the cardiomyocytes, leading to reduced removal of cytosolic calcium. After induction of Serca2 gene disruption, these mice develop marked diastolic dysfunction as well as impaired contractility. SERCA2 knockout (SERCA2KO) mice were treated with levosimendan or vehicle from the time of KO induction. At the 7-wk end point, cardiac function was assessed by echocardiography and pressure measurements. Vehicle-treated SERCA2KO mice showed significantly diminished left-ventricular (LV) contractility, as shown by decreased ejection fraction, stroke volume, and cardiac output. LV pressure measurements revealed a marked increase in the time constant (τ) of isovolumetric pressure decay, showing impaired relaxation. Levosimendan treatment significantly improved all three systolic parameters. Moreover, a significant reduction in τ toward normalization indicated improved relaxation. Gene-expression analysis, however, revealed an increase in genes related to production of the ECM in animals treated with levosimendan. In conclusion, long-term levosimendan treatment improves both contractility and relaxation in a heart-failure model with marked diastolic dysfunction due to reduced calcium transients. However, altered gene expression related to fibrosis was observed.

scholarly journals Oral delivery of xenon for cardiovascular protection

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xing Yin ◽  
Melanie R. Moody ◽  
Valeria Hebert ◽  
Melvin E. Klegerman ◽  
Yong-Jian Geng ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Oral Delivery ◽  
Noble Gas ◽  
Left Ventricular ◽  
Beneficial Effects ◽  
Normal Left Ventricular ◽  
Term Administration ◽  
Apoe Knockout Mice

Abstract Cardiac hypertrophy often causes impairment of cardiac function. Xenon (Xe), a naturally occurring noble gas, is known to provide neurological and myocardial protection without side effects. The conventional method of Xe delivery by inhalation is not feasible on a chronic basis. We have developed an orally deliverable, effective Xe formulation for long-term administration. We employed 2-hydroxypropyl)-β-cyclodextrin (HPCD), which was dissolved in water to increase the Xe concentration in solution. The beneficial effects of long-term oral administration of Xe-enriched solutions on cardiovascular function were evaluated in vivo. HPCD increased Xe solubility from 0.22 mM to 0.67 mM (3.8-fold). Aged ApoE knockout mice fed high-fat diet for 6 weeks developed hypertension, and myocardial hypertrophy with impaired cardiac function. Oral Xe prevented this ischemic damage, preserving normal blood pressure, while maintaining normal left ventricular mass and wall thickness. This novel formulation allows for gastrointestinal delivery and cardiovascular stabilization.

Long-term Outcomes of Isolated CABG with Reduced Left Ventricular Function

2017 ◽  
Vol 23 (10) ◽  
pp. S34
Author(s):  
Hiroki Hata ◽  
Koici Toda ◽  
Shigeru Miyagawa ◽  
Yasushi Yoshikawa ◽  
Shunsuke Saito ◽  
...  
Keyword(s):  
Left Ventricular Function ◽  
Ventricular Function ◽  
Left Ventricular ◽  
Long Term Outcomes
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