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PubMed1996

Gender differences in the relation between interview-derived hostility scores and resting blood pressure.

We examined the correlations between Structured Interview (SI)-derived hostility scores and resting blood pressure (BP) to see if they would be the same or different for healthy men and women. Standard risk factor information and resting BP measures were obtained from 193 undergraduates (109 men, 84 women), who underwent the SI. Subjects were rated for Potential for Hostility, Hostile Style, Intensity and Content, and completed Antagonism and Neuroticism scales. As expected, SI hostility scores were related to higher resting SBP in men, however; in women, they were related to lower resting SBP and Neuroticism. Regression analyses controlling for standard CHD risk factors indicated that SI-derived hostility predicted resting SBP and hypertensive status in both men and women, though in opposite directions. Thus, SI-derived hostility may assess a different construct in women than in men.

Arousal↗
PubMedDate not supplied

Rest- and stimulation-dependent changes in exchangeable calcium content in rabbit ventricular myocardium.

Ca2+ shifts in the isolated, perfused ventricular muscle of rabbit hearts were investigated with the aid of 45Ca under the conditions of complete equilibration of preparations with 45Ca containing solution. The "cellular" 45Ca content was calculated by subtraction of 45Ca2+ dissolved in the free water of extracellular space from the total tissue 45Ca2+ content. The "cellular" content of 45Ca in stimulated (60 per min) preparation was 0.887 +/- 0.067 mmol/kg wet weight (w.w.). Six minutes of rest resulted in the drop of this content to 0.503 +/- 0.054 mmol/kg w.w. despite continued perfusion with 45Ca containing solution. Contractile force (CF) decreased at that time to 23% of control. The first post-rest contraction (RSC) resulted in a gain of 0.073 mmol45Ca/kg w.w. Both the content of 45Ca and CF returned to the pre-rest values when stimulation was resumed. The difference between the 45Ca content of post-rest stimulated and rested preparations (0.384 mmol/kg w.w.) is equivalent to Ca2 fraction (Ca2), previously described in guinea pig ventricular myocardium (17, 12). However, the volume of rabbit Ca2 is only about 42% of that in guinea pig. Caffeine in concentration 12.5 mM, which did not displace Ca2 from guinea pig ventricular muscle, decreased Ca2 in the rabbit ventricle by 44%. CCCP, a protonofore destroying the mitochondrial protone gradient essential for Ca2+ uptake and maintainability, displaced Ca2 completely from rabbit ventricles. These results, although far from conclusive, do suggest that both the mitochondria and sarcoplasmic reticulum might be the site of the rate-dependent Ca2 fraction. The physiological meaning of differences in Ca2 content between rabbit, guinea pig, and rat ventricular myocardium is discussed.

Animals↗
PubMed1996

The Na/K pump, resting potential and selective permeability in canine Purkinje fibres at physiologic and room temperatures.

All mammalian cells maintain a resting potential generated by ions moving down concentration gradients. In excitable cells, the inside potential is negative relative to outside. In order to maintain this electrochemical gradient, the sodium potassium (Na/K) pump actively transports out three sodium ions for every two potassium ions it brings in. This process generates a net outward current and thus hyperpolarizes the resting potential. I employed dihydroouabain (DHO) to inhibit the Na/K pump and thus measure its contribution to the resting potential. It contributed 9.0 mV at 34 degrees C and 3.8 mV at 25 degrees C. The PK/PNa ratios were calculated at both temperatures before and after subtracting the Na/K pump contribution. These ratios also suggested a decreased contribution of the Na/K pump under hypothermia. Taken together, these results suggest that the pump contribution to the resting potential is more significant at physiologic temperatures (34 degrees C) than at room temperature (25 degrees C), and that estimates of selective permeability can only be accurately obtained after assessing and eliminating the Na/K pump contribution to the resting potential.

Animals↗
PubMed1999

[Problems of clinical evaluation of hemodynamics at rest and during exercise in chronic heart disease. Value of cardiac catheterization and problems of clinical classification].

BACKGROUND: NYHA classification is mostly used for graduation of clinical limitation due to cardiac failure. Right heart catheterization is not generally used to evaluate hemodynamics and to define the effects of drugs in patients with chronic cardiac failure. Clinical data and results from echocardiography, stress tests or nuclear cardiology seem to be sufficient. Our aim was to demonstrate subjectivity of a classification system (NYHA) comparing the graduation done by physicians and by patients and to represent the difficulty to prognosticate hemodynamic data of patients with heart failure. PATIENTS AND METHODS: Limitation of 53 patients with heart diseases was classified by physicians and patients using NYHA classification. Pulmonary capillary wedge pressure (PCWP), stroke volume (SV) and cardiac output were predicted by physicians; they were allowed to utilize all examination data they could get. Predicted hemodynamic data were compared with the results of measurement at rest and during exercise. RESULTS: Patients classified themselves significantly worse than physicians did: 2.68 +/- 0.64 vs. 2.23 +/- 0.74 (p = 0.0012). Similarity in NYHA classification was found in 29/53 cases. Correlation of predicted and measured hemodynamic data was low: PCWP (at rest) r = 0.346; PCWP (during exercise) r = 0.232; SV (at rest) r = 0.476; SV (during exercise) r = 0.445; HMV (at rest) r = 0.412; HMV (during exercise) r = 0.538. CONCLUSION: Clinical classification systems like NYHA are subjective, classification by physicians differs significantly from classification by patients. Prediction of hemodynamics is not possible despite all examination data had been available. Right heart catheterization is necessary to define hemodynamics at rest and during exercise.

Cardiac Catheterization↗
PubMed1996

Effects of alprazolam and lorazepam on catecholaminergic and cardiovascular activity during supine rest, mental load and orthostatic challenge.

Effects of oral alprazolam (0.5 and 1 mg) and lorazepam (2 mg) on sympathetic adrenomedullary activity and sedation were studied during supine rest, mental load (Color Word Test, CWT) and active standing (OCT), in 12 male volunteers in a randomized double-blind placebo-controlled cross-over design. Compared to placebo, alprazolam significantly increased subjective sedation, reduced plasma adrenaline and noradrenaline concentrations and mean blood pressure (MBP) during supine rest, and attenuated plasma adrenaline responses during the CWT and the OCT; these effects during the CWT and OCT appeared to be dose-dependent. In comparison with lorazepam (2 mg), alprazolam (1 mg) showed reduced MBP levels during supine rest, whereas lorazepam showed a higher heart rate level during supine rest, a reduced plasma noradrenaline response to the OCT and a performance deterioration to the CWT. There were no differences between alprazolam (1 mg) and lorazepam regarding subjective sedation. Although the benzodiazepines were similar regarding their increase of sedation, alprazolam and lorazepam induced differential effects on sympathetic adrenomedullary activity during rest and stress, whereby suppression of adrenomedullary activity may be specific for alprazolam.

Adult↗
PubMed2000

Prediction of improvement in global left ventricular function in patients with chronic coronary artery disease and impaired left ventricular function: rest thallium-201 SPET versus low-dose dobutamine echocardiography.

Accurate assessment of myocardial viability permits selection of patients who would benefit from myocardial revascularization. Currently, rest-redistribution thallium-201 scintigraphy and low-dose dobutamine echocardiography are among the most used techniques for the identification of viable myocardium. Thirty-one consecutive patients (all men, mean age 60 +/- 8 years) with chronic coronary artery disease and reduced left ventricular ejection fraction (31% +/- 7%) were studied. Rest 201Tl single-photon emission tomography (SPET), low-dose dobutamine echocardiography and radionuclide angiography were performed before revascularization. Radionuclide angiography and echocardiography were repeated after revascularization. An a/dyskinetic segment was considered viable on 201Tl SPET when tracer uptake was >65%, while improvement on low-dose dobutamine echocardiography was considered a marker of viability. Increase in global ejection fraction was considered significant at > or = 5%. In identifying viable segments, rest 201Tl SPET showed higher sensitivity than low-dose dobutamine echocardiography (72% vs 53%, P<0.05), while specificity was not significantly different (86% vs 88%). In 17 patients, global ejection fraction increased > or = 5% (group 1) while in 14 it did not (group 2). A higher number of a/dyskinetic segments were viable on 201Tl SPET in group 1 than in group 2 (2.6 +/- 1.9 vs 0.6 +/- 1.2, P < 0.005), while no significant differences were observed on low-dose dobutamine echocardiography (1.7 +/- 1.6 vs 1.1 +/- 1.6). A significant correlation was found between the number of a/dyskinetic segments viable on 201Tl SPET and post-revascularization changes in ejection fraction (r = 0.52, P < 0.05), but such a correlation was not observed for low-dose dobutamine echocardiography. Using as the cut-off the presence of at least one viable a/dyskinetic segment, rest 201Tl SPET had a higher sensitivity (82% vs 53%, P = 0.07) and showed a trend towards higher accuracy and specificity (77% vs 58%, and 71% vs 64%, respectively) as compared with low-dose dobutamine echocardiography. In conclusion, these findings suggest that when severely reduced global function is present, rest 201Tl SPET evaluation of viability is more accurate than low-dose dobutamine echocardiography for the identification of patients who will benefit most from revascularization.

Adrenergic beta-Agonists↗
PubMed1998

Combined evaluation of rest-redistribution thallium-201 tomography and low-dose dobutamine echocardiography enhances the identification of viable myocardium in patients with chronic coronary artery disease.

The purpose of this study was to evaluate whether combined evaluation by discriminant analysis of rest-redistribution thallium-201 tomography and low-dose dobutamine echocardiography enhances the accuracy in identifying viable myocardium in patients with chronic coronary artery disease. Rest-redistribution 201Tl has high sensitivity but low specificity in identifying viable myocardium, while the opposite is true for low-dose dobutamine echocardiography. Forty-six patients underwent low-dose dobutamine echocardiography and rest-redistribution 201Tl tomography on the same day. Rest echocardiography was repeated at least 30 days (mean 40+/-20) after myocardial revascularization. Discriminant analysis was applied to the results of 201Tl tomography and dobutamine echocardiography to classify a/dyskinetic segments as viable or non-viable. In 92 a/dyskinetic segments that were revascularized, rest-redistribution 201Tl tomography yielded an accuracy of 75%, while the accuracy of dobutamine echocardiography was 70% (P<0.05). When discriminant analysis was used, the combined evaluation gave an accuracy of 83% (P<0.05 vs both tests). These findings demonstrate that low-dose dobutamine echocardiography and 201Tl imaging are useful and complementary techniques for identifying viable myocardium in patients with chronic coronary artery disease. Combined evaluation by discriminant analysis significantly improves accuracy, although the cost-effectiveness of such an approach remains to be determined.

Adrenergic beta-Agonists↗
PubMed2003

To stay or not to stay: the contribution of tactile and thermal cues to coming to rest in newborn rabbits.

Newborn rabbits, like other altricial mammals, demonstrate thermotaxis and when placed on a thermal gradient locate and come to rest at physiologically appropriate temperatures. Little is known, however, about the sensory-motor components contributing to the in energetic terms important decision of the young to cease locomotion and come to rest. We investigated the behavior of newborn rabbits on two thermal gradients; linear in which pups could use tactile cues from the arena wall, and concentric in which pups were unable to use such cues. On both gradients pups located the warm, thermal-neutral area within the 200-s test time, thereby demonstrating their ability to orient appropriately using thermal cues alone. Unexpectedly, however, pups on the concentric gradient failed, or took significantly longer, to come to rest than pups on the linear gradient. Since the speed of locomotion of pups on the linear gradient was significantly slowed when they were in contact with the arena wall, and in most cases they came to rest in contact with it, we suggest that not only thermal but also tactile cues may be important in bringing young mammals to rest in a thermally appropriate environment.

Animals↗
PubMed1999

Asian small-clawed otters (Amblonyx cinerea): resting and swimming metabolic rates.

Open-flow oxygen and carbon dioxide respirometry was used in Neumünster Zoo (Germany) to examine the energy requirements of six Asian small-clawed otters (Amblonyx cinerea) at rest and swimming voluntarily under water. Our aim was to compare their energy requirements with those of other warm-blooded species to elucidate scale effects and to test whether the least aquatic of the three otter species differs markedly from these and its larger relatives. While at rest on land (16 degrees C, n = 26), otters (n = 6, mean body mass 3.1 +/- 0.4 kg) had a respiratory quotient of 0.77 and a resting metabolic rate of 5.0 +/- 0.8 Wkg-1(SD). This increased to 9.1 +/- 0.8 Wkg-1 during rest in water (11-15 degrees C, n = 4) and to 17.6 +/- 1.4 Wkg-1 during foraging and feeding activities in a channel (12 degrees C, n = 5). While swimming under water (n = 620 measurements) in an 11-m long channel, otters preferred a speed range between 0.7 ms-1 and 1.2 ms-1. Transport costs were minimal at 1 ms-1 and amounted to 1.47 +/- 0.24 JN-1 m-1 (n = 213). Metabolic rates of small-clawed otters in air were similar to those of larger otter species, and about double those of terrestrial mammals of comparable size. In water, metabolic rates during rest and swimming were larger than those extrapolated from larger otter species and submerged swimming homeotherms. This is attributed to high thermoregulatory costs, and high body drag at low Reynolds numbers.

Animals↗
PubMed2000

Resting metabolic rate in Italians: relation with body composition and anthropometric parameters.

The objectives of this study were to obtain values for resting metabolic rate in Italians in relation to parameters of body composition, and to compare them to predicted values using the FAO/WHO/UNU equation. We performed a cross-sectional observational study of 131 healthy subjects (46 males and 85 females) at the Human Nutrition Unit, University Tor Vergata, Rome. Body composition was determined by dual energy X-ray absorptiometry (DXA) and resting metabolic rate was calculated using the Weir formula. Resting metabolic rate was 1,865 +/- 234 kcal/day in males and 1,354 +/- 154 kcal/day in females. These values decreased slightly with age. The relationships with weight and age were stronger than that with lean mass from DXA as independent variables in multiple regression analysis. Mean resting metabolic rates predicted with FAO/WHO/UNU and Harris-Benedict formula were not significantly different from measured values except for the Harris-Benedict value for females (p < 0.01). Individual differences between measured and predicted values were notably high. The measured values were higher than those reported in the literature. The prediction of resting metabolic rate is more accurate with simple anthropometric parameters than with fat-free mass obtained by DXA. The individual error in the predicted values can be so high that for individual use a measured value is preferred over an estimated value.

Absorptiometry, Photon↗
PubMed2005

The effect of peritoneal rest in combination therapy of peritoneal dialysis and hemodialysis: using the cultured human peritoneal mesothelial cell model.

The effects of peritoneal rest for 24 h during peritoneal dialysis and hemodialysis combination therapy were investigated using cultured human peritoneal mesothelial cell (HPMC) models. Cell activity was investigated by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenylterazolium bromide (MTT) assay after exposing HPMCs to peritoneal dialysis fluids (PDFs) with different pH levels. The following PDFs (50 microl/well) were used for exposure durations of 30 or 240 min: acidic heat-sterilized PDFs (L-H PDF, pH 5.5) and neutral heat-sterilized PDFs (N-H PDF, pH 6.7). Control wells were exposed to M-199 Hanks medium containing 20% fetal bovine serum (FBS) for 30 or 240 min. Supernatants were then aspirated from each well and M-199 culture medium containing 20% FBS (50 microl) was added to each well to rest HPMCs for 24 h before investigation of MTT activity. The activity of HPMCs exposed to L-H PDF for 240 min decreased to approximately 20% and 15% when compared with controls (glucose concentrations of 1.36% and 3.86%, respectively; P < 0.01 versus control, Tukey-Kramer test), and to approximately 60% and 40% after exposure to N-H PDF for 240 min (glucose: 1.36% and 3.86%; P < 0.01). The activity of HPMCs exposed to L-H PDF for 240 min followed by rest was approximately 20% and 4% when compared with controls (glucose: 1.36% and 3.86%; P < 0.01) and was 93% and 96% when compared with controls after exposure to N-H PDF for 240 min followed by rest (glucose: 1.36% and 3.86%). These findings suggest that rest for 24 h after exposure to N-H PDF improves the activity of HPMCs.

Cell Survival↗
PubMed2005

The effect of oral administration of L-arginine on anal resting pressure and anodermal blood flow in healthy volunteers.

BACKGROUND: Topical application of L-arginine, the precursor of nitric oxide, reduces anal resting pressure without significant side effects and may therefore be of benefit in the treatment of anal fissure. This in vivo study investigated the effect of orally administered L-arginine on anal resting pressure and anodermal blood flow in healthy volunteers. METHODS: Eight healthy volunteers took 3 sachets of Arginaid (Novartis Consumer Health, Breda, The Netherlands) containing 15 g L-arginine on a daily basis, for 7 days. At the start of the experiment (day 0) and on days 3 and 7, plasma levels of L-arginine, anal resting pressures and anodermal blood flow were determined. RESULTS: Arginine plasma levels increased from 107.0+/-8.6 micromol/l (day 0) to 283.7+/-44.0 micromol/l on day 3 (p< 0.01) and remained elevated at day 7 (157.3+/-19.6 micromol/l, p<0.05). Anodermal blood flow and anal resting pressures were similar on days 0, 3 and 7. CONCLUSIONS: Oral administration of 15 g arginine in healthy volunteers on a daily basis increased arginine plasma levels but had no influence on anodermal blood flow and anal resting pressure.

Administration, Oral↗
PubMed1992

Temporal increase in resting coronary blood flow causes an impairment of coronary flow reserve after coronary angioplasty.

Impaired coronary flow reserve immediately after coronary angioplasty may be attributed to an increase in resting coronary blood flow. To test this hypothesis we measured great cardiac venous flow (GCVF) at rest and during rapid atrial pacing before and immediately after angioplasty in 22 patients with significant narrowing of the left anterior descending artery and 12 patients (control group) with minimal narrowing. A follow-up (6 months) study was also done in seven patients. Immediately after angioplasty the coronary flow reserve (peak GCVF during pacing/resting GCVF) was not fully restored (1.5 +/- 0.36 before angioplasty, 1.76 +/- 0.42 after angioplasty, and 2.13 +/- 0.33 in the control group). Resting coronary vascular resistance (2.4 +/- 0.9 mm Hg/ml/min) was significantly decreased after angioplasty (2.0 +/- 0.8 mm Hg/ml/min), whereas coronary vascular resistance during rapid pacing was fully restored to normal. Resting hyperemia was restored 6 months later, whereas coronary vascular resistance during pacing was unaltered. In five patients, however, slight ischemic ST-T changes were observed during rapid pacing, even after successful angioplasty associated with a decrease in the lactate extraction ratio. These results indicate that the impaired coronary flow reserve immediately after angioplasty may be attributed mainly to the temporal but significant increase in resting coronary flow, although impaired coronary vascular response to augmented myocardial oxygen demand may also be partially involved.

Aged↗
PubMed1993

Reinjection as an alternative to rest imaging for detection of exercise-induced ischemia with thallium-201 emission tomography.

Exercise thallium-201 single photon emission computed tomography images were compared prospectively with 4-hour redistribution images, with 4-hour reinjection images, and with images obtained at rest on a separate day in 37 patients with documented coronary artery disease. Exercise images were abnormal in 35 patients (95%). On the basis of an improvement in thallium-201 distribution between exercise and nonexercise images, overall sensitivity for the detection of coronary artery stenosis was significantly higher with reinjection at 4 hours (p < 0.05) or with a rest injection on a separate day (p < 0.05) than with redistribution imaging (84%, 83%, and 70%, respectively). Reinjection and rest injection were positive more frequently in patients with a wall-motion abnormality (76% and 80%, respectively, vs 64% at redistribution; p < 0.05 for both) or with > 90% stenosis (77% and 76%, respectively, vs 58% at redistribution; p < 0.05 for both). Among the 11 patients who had no evidence of redistribution at 4 hours, five (45%) demonstrated ischemia with reinjection and five demonstrated ischemia in the separate rest study; a total of seven patients showed improvement either at reinjection or rest. Among these 86% had a wall-motion abnormality associated with stenosis of > 90%, whereas in the other 30 patients these two conditions were observed concomitantly in only 43%. This study demonstrates that the thallium-201 4-hour postexercise reinjection technique is as sensitive as the 2-day rest/exercise method for the detection of coronary artery stenosis and provides additional information when a severe stenosis is associated with a wall-motion abnormality.

Aged↗
PubMed1993

Comparative prognostic value of clinical risk indexes, resting two-dimensional echocardiography, and dipyridamole stress thallium-201 myocardial imaging for perioperative cardiac events in major nonvascular surgery patients.

The relative prognostic value of widely accessible resting two-dimensional echocardiographic ventricular function data has not been compared with recognized clinical and scintigraphic risk markers in patients who are unable to exercise before major nonvascular surgery. To this end, 53 consecutive patients aged 67 +/- 13 years undergoing preoperative evaluation (intraabdominal, 23%; orthopedic, 30%; thoracic, 9%; other, 38%) for known or suspected coronary artery disease were followed up to evaluate the prognostic value of these studies for the perioperative cardiac events (cardiac death [n = 4], myocardial infarction [n = 2], unstable angina [n = 3], and pulmonary edema [n = 8]) that occurred in 13 of the 53 patients (25%). Dipyridamole thallium-201 myocardial redistribution defects occurred in 15 (28%) patients. Resting echocardiographic left ventricular dysfunction was present in 21 (40%) patients. Multivariate analysis of clinical, echocardiographic, and scintigraphic risk predictors revealed that cardiac events were not predicted by clinical variables, including Goldman class or score. Cardiac events were independently predicted only by the presence of significant left ventricular dysfunction on resting two-dimensional echocardiography (p < 0.042) and dipyridamole thallium-201 defect redistribution (p < 0.026). A dipyridamole-induced reversible thallium-201 perfusion defect was predictive of subsequent cardiac death or myocardial infarction (p < 0.02), whereas left ventricular dysfunction on resting echocardiography was predictive of perioperative pulmonary edema (p < 0.023). We conclude that stress thallium-201 perfusion imaging and resting two-dimensional echocardiography provide independent prognostic information in patients undergoing major nonvascular surgery who are at significant risk for ischemic cardiac events and who are unable to perform standard exercise stress tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1976

Beneficial effects of nitroglycerin on abnormal ventricular wall motion at rest and during exercise in patient with previous myocardial infarction.

The effects of sublingually administered nitroglycerin on segmental left ventricular wall motion determined by videotracking and radiographic left heart size were evaluated at rest and during submaximal hand grip exercise in 10 patients with previous transmural myocardial infarction. After nitroglycerin, diastolic left heart size decreased in the resting state from an average of 49.5 +/- 5.7 (standard deviation) to 47.9 +/- 5.6 mm/m2 body surface area (P less than 0.01) and during handgrip exercise from a mean of 50.7 +/- 590 to 49.1 +/- 4.7 mm/m2 (P less than 0.05). In the resting state, the average maximal velocity of shortening in segments with normal wall motion increased after nitroglycerin from 18.1 +/- 3.0 to 23.5 +/- 5.5 mm/sec (P less than 0.01), whereas during handgrip exercise alone, the velocity of shortening averaged 25.6 +/- 6.9 mm/sec and increased further after nitroglycerin to 30.1 +/- 10.6 mm/sec (P less than 0.05). The effects of nitroglycerin on the average extent of shortening in normal segments were similar. In all 10 patients, there was a decrease in the number of segments with abnormal wall motion. The number of sites with dyssynergy decreased after nitroglycerin from 24 to 15 in the resting state and from 40 to 22 when nitroglycerin was administered before handgrip exercise. Sublingually administered nitroglycerin appears to decrease left heart size, increase the velocity and extent of shortening in normal left ventricular segments and often reduce the extent of left ventricular wall motion abnormalities at rest and during isometric exercise in patients with previous transmural myocardial infarction.

Adult↗
PubMed1982

Effects of acute and chronic minoxidil administration on rest and exercise hemodynamics and clinical status in patients with severe, chronic heart failure.

The effects of acute and chronic oral administration of the vasodilator minoxidil on hemodynamics, oxygen consumption, exercise performance, and clinical status were investigated in 10 patients with severe, chronic heart failure refractory to digitalis and diuretic therapy. The cardiac index was 1.99 +/- 0.38 liters/min/m2 at rest and 2.88 +/- 0.79 at symptom-limited maximal exercise on conventional therapy, compared with 2.64 +/- 0.33 liters/min/m2 at rest and 3.55 +/- 0.84 at maximal exercise after short-term minoxidil administration (p less than 0.02, control versus minoxidil at both rest and exercise). Stroke volume was increased after minoxidil treatment, without significant effect on heart rate. Systemic vascular resistance was decreased by minoxidil from 2,050 +/- 722 to 1,325 +/- 374 dynes . s/cm-5 at rest and from 1,500 +/- 830 to 1,206 +/- 589 dynes . s/cm-5 at maximal exercise (p = 0.01, control versus minoxidil). No significant effect was observed on left ventricular filling, right atrial, or mean pulmonary arterial pressure, but pulmonary vascular resistance decreased both at rest and on exercise (p less than 0.05). Maximal exercise oxygen consumption increased from 8.9 +/- 3.2 ml/kg/min on conventional therapy to 10.5 +/- 2.4 on minoxidil therapy (p less than 0.03), median maximal exercise work load increased from 25 to 50 W and medium exercise duration increased from 6.0 to 9.0 minutes. On chronic minoxidil administration all 5 patients who completed a scheduled 6 week follow-up showed symptomatic improvement. However, worsening edema developed in all patients, requiring increased diuretic dosage and close supervision. Symptoms of ischemic heart disease worsened in 2 of 10 patients. We tentatively conclude that minoxidil may be a useful vasoactive agent in the pharmacologic therapy of severe chronic heart failure.

Adult↗
PubMed1982

Accuracy of cardiac output, oxygen uptake, and arteriovenous oxygen difference at rest, during exercise, and after vasodilator therapy in patients with severe, chronic heart failure.

Measurement of cardiac output, arteriovenous oxygen difference, and oxygen uptake in patients with heart failure may be subject to technical and biologic inaccuracies. We measured these 3 variables in 16 patients with chronic heart failure at rest and during exercise. When cardiac output was measured by thermodilution and compared with values calculated by the Fick principle, there was a significant correlation at rest (r = 0.91, p less than 0.001) and at exercise (r = 0.93, p less than 0.001). When the arteriovenous oxygen difference was measured by spectrophotometry of arterial and mixed venous samples and compared with values calculated by the Fick principle, there was a significant correlation at rest (r = 0.80, p less than 0.01) and at exercise (r = 0.76, p less than 0.01). When oxygen uptake was measured from expired gas analysis and compared with values calculated by the Fick principle, there was a significant correlation at rest (r = 0.84, p less than 0.01) and at exercise (r = 0.94, p less than 0.001). In addition, 10 patients received vasodilator treatment which increased cardiac output and decreased the arteriovenous oxygen difference at rest and exercise. There was no significant difference between measured and calculated values for the 3 variables under those additional conditions. It is concluded that despite technical and biologic difficulties, cardiac output, arteriovenous oxygen difference, and oxygen uptake, when calculated from Fick's principle, yield results equivalent to direct measurement.

Adult↗