Magnetic Resonance–Derived 3-Dimensional Blood Flow Patterns in the Main Pulmonary Artery as a Marker of Pulmonary Hypertension and a Measure of Elevated Mean Pulmonary Arterial Pressure

The objective of these experiments was to determine whether living and training in moderate hypoxia (MHx) confers an advantage on maximal normoxic exercise capacity compared with living and training in normoxia. Rats were acclimatized to and trained in MHx [inspired Po 2(Pi O2 ) = 110 Torr] for 10 wk (HTH). Rats living in normoxia trained under normoxic conditions (NTN) at the same absolute work rate: 30 m/min on a 10° incline, 1 h/day, 5 days/wk. At the end of training, rats exercised maximally in normoxia. Training increased maximal O2 consumption (V˙o 2 max) in NTN and HTH above normoxic (NS) and hypoxic (HS) sedentary controls. However,V˙o 2 max and O2 transport variables were not significantly different between NTN and HTH:V˙o 2 max 86.6 ± 1.5 vs. 86.8 ± 1.1 ml · min−1 · kg−1; maximal cardiac output 456 ± 7 vs. 443 ± 12 ml · min−1 · kg−1; tissue blood O2 delivery (cardiac output × arterial O2 content) 95 ± 2 vs. 96 ± 2 ml · min−1 · kg−1; and O2 extraction ratio (arteriovenous O2 content difference/arterial O2 content) 0.91 ± 0.01 vs. 0.90 ± 0.01. Mean pulmonary arterial pressure (Ppa, mmHg) was significantly higher in HS vs. NS ( P < 0.05) at rest (24.5 ± 0.8 vs. 18.1 ± 0.8) and during maximal exercise (32.0 ± 0.9 vs. 23.8 ± 0.6). Training in MHx significantly attenuated the degree of pulmonary hypertension, with Ppa being significantly lower at rest (19.3 ± 0.8) and during maximal exercise (29.2 ± 0.5) in HTH vs. HS. These data indicate that, despite maintaining equal absolute training intensity levels, acclimatization to and training in MHx does not confer significant advantages over normoxic training. On the other hand, the pulmonary hypertension associated with acclimatization to hypoxia is reduced with hypoxic exercise training.

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The response of the pulmonary circulation to exercise during normoxia and hypoxia following pneumonectomy in the adult sheep

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y89-034 ◽

1989 ◽

Vol 67 (3) ◽

pp. 202-206 ◽

Cited By ~ 2

Author(s):

Michele Smith ◽

Geoffrey Coates ◽

J. Michael Kay ◽

Hugh O'Brodovich

Keyword(s):

Blood Flow ◽

Arterial Pressure ◽

Pulmonary Arterial Pressure ◽

Hemodynamic Response ◽

Pulmonary Hemodynamics ◽

Vascular Reserve ◽

Mean Pulmonary Arterial Pressure ◽

Pulmonary Hemodynamic ◽

Pulmonary Arterial ◽

Increased Blood Flow

Pneumonectomy approximately halves the available pulmonary vascular bed. It is unknown whether the remaining lung has sufficient vascular reserve to cope with increased blood flow under stressful conditions without demonstrating abnormal pulmonary hemodynamics. To investigate this question, unanesthetized ewes with vascular catheters had hemodynamics assessed before and after a left pneumonectomy. Subsequently, on different days, the sheep were exercised on a treadmill under normoxic and hypobaric hypoxic (430 mmHg) (1 mmHg = 133.3 Pa) conditions. Pneumonectomy itself increased mean pulmonary arterial pressure by 4 mmHg. During normoxic or hypoxic exercise, the pneumonectomized sheep demonstrated a pulmonary hemodynamic response similar to normal sheep with two lungs. The pressure–flow relation for the right lung suggested the vascular reserve of the lung was not exceeded during exercise in the pneumonectomized sheep. Eighteen to 70 days after pneumonectomy there was no evidence of right ventricular hypertrophy, but there were small increases in the number of muscularized vessels less than 50 μm diameter and in the amount of muscle in normally muscularized pulmonary arteries. This study demonstrates that pneumonectomy slightly increases mean pulmonary arterial pressure. However, there is sufficient vascular reserve in the remaining lung to permit a normal hemodynamic response to exercise-induced increased blood flow even under hypoxic conditions.Key words: pulmonary hypertension, pneumonectomy, sheep.

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Correlation of acute with chronic hypoxic pulmonary hypertension in cattle

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.3.495 ◽

1975 ◽

Vol 38 (3) ◽

pp. 495-498 ◽

Cited By ~ 22

Author(s):

D. H. Will ◽

J. L. Hicks ◽

C. S. Card ◽

J. T. Reeves ◽

A. F. Alexander

Keyword(s):

Pulmonary Hypertension ◽

Arterial Pressure ◽

Pulmonary Arterial Pressure ◽

Pressor Response ◽

Acute Hypoxia ◽

Common Mechanism ◽

Mean Pulmonary Arterial Pressure ◽

Pressor Responses ◽

Pulmonary Arterial ◽

Highly Correlated

We investigated acute and chronic hypoxic pulmonary pressor responses in two groups of calves, one bred to be susceptible, the other resistant to high-altitude pulmonary hypertension. Twelve 5-mo-old susceptible calves residing at 1,524 m increased their mean pulmonary arterial pressure from 26 +/- 2 (SE) to 55 +/- 4 mmHg during 2 h at a simulated altitude of 4,572 m. In 10 resistant calves pressure increased from 22 +/- 1 to 37 +/- 2 mmHg. Five calves were selected from each group for further study. When 9 mo old, the 5 susceptible calves again showed a greater pressor response to acute hypoxia (27 +/- 1 to 55 +/- 4 mmHg) than did 5 resistant calves (23 +/- 1 to 41 +/- 3 mmHg). When 12 mo old, the 5 susceptible calves also developed a greater increase in pulmonary arterial pressure (21 +/- 2 to 9 +/- 4 mmHg) during 18 days at 4,572 m than did the 5 resistant calves (21 +/- 1 to 64 +/- 4 mmHg). Acute and chronic hypoxic pulmonary pressor responses were highly correlated (r = 0.91; P less than 0.001) indicating that they were probably produced through a common mechanism.

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Impact of the updated hemodynamic definitions on diagnosis rates of pulmonary hypertension

Pulmonary Circulation ◽

10.1177/2045894020931299 ◽

2020 ◽

Vol 10 (3) ◽

pp. 204589402093129

Author(s):

Seda Tanyeri ◽

Ozgur Y. Akbal ◽

Berhan Keskin ◽

Aykun Hakgor ◽

Ali Karagoz ◽

...

Keyword(s):

Pulmonary Hypertension ◽

Arterial Pressure ◽

European Society ◽

Pulmonary Arterial Pressure ◽

Heart Catheterization ◽

Mean Pulmonary Arterial Pressure ◽

Pressure Threshold ◽

Normal Mean ◽

Pulmonary Arterial ◽

European Society Of Cardiology

We evaluated whether updated pulmonary hypertension definitive criteria proposed in sixth World Symposium on Pulmonary Hypertension had an impact on diagnosis of overall pulmonary hypertension and pre-capillary and combined pre- and post-capillary phenotypes as compared to those in European Society of Cardiology/European Respiratory Society 2015 pulmonary hypertension Guidelines. Study group comprised the retrospectively evaluated 1300 patients (age 53.1 ± 18.8 years, female 807, 62.1%) who underwent right heart catheterization with different indications between 2006 and 2018. Mean pulmonary arterial pressure ≥25 mmHg (European Society of Cardiology) and PAMP (mean pulmonary arterial pressure) >20 mmHg (World Symposium on Pulmonary Hypertension) right heart catheterization definitions criteria were used, respectively. For pre-capillary pulmonary hypertension, pulmonary artery wedge pressure ≤15 mmHg and pulmonary vascular resistance ≥3 Wood units criteria were included in the both definitions. Normal mean pulmonary arterial pressure (<21 mmHg), borderline mean pulmonary arterial pressure elevation (21–24 mmHg), and overt pulmonary hypertension (≥25 mmHg) were documented in 21.1, 9.8, and 69.1% of the patients, respectively. The pre-capillary and combined pre- and post-capillary pulmonary hypertension were noted in 2.9 and 1.1%, 8.7 and 2.5%, and 34.6 and 36.6% of the patients with normal mean pulmonary arterial pressure, borderline, and overt pulmonary hypertension subgroups, respectively. The World Symposium on Pulmonary Hypertension versus European Society of Cardiology/European Respiratory Society definitions resulted in a net 9.8% increase in the diagnosis of overall pulmonary hypertension whereas increases in the pre-capillary pulmonary hypertension and combined pre- and post-capillary pulmonary hypertension diagnosis were only 0.8 and 0.3%, respectively. The re-definition of mean pulmonary arterial pressure threshold seems to increase the frequency of the overall pulmonary hypertension diagnosis. However, this increase was mainly originated from those in post-capillary pulmonary hypertension subgroup whereas its impact on pre-capillary and combined pre- and post-capillary pulmonary hypertension was negligible. Moreover, criteria of pre-capillary pulmonary vascular disease and combined pre- and post-capillary phenotypes were still detectable even in the presence of normal mean pulmonary arterial pressure. The obligatory criteria of pulmonary vascular resistance ≥3 Wood units seems to keep specificity for discrimination between pre-capillary versus post-C pulmonary hypertension after lowering the definitive mean pulmonary arterial pressure threshold to 20 mmHg.

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