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PubMed1984

Nifedipine inhibits hypoxic pulmonary vasoconstriction during rest and exercise in patients with chronic obstructive pulmonary disease. A controlled double-blind study.

To determine whether nifedipine reduces pulmonary artery pressure and pulmonary vascular resistance index during rest and exercise in patients with hypoxic pulmonary hypertension, we studied 6 clinically stable patients using a randomized, double-blind, crossover design. While patients were hypoxic, nifedipine significantly lowered mean pulmonary artery pressure during rest from (mean +/- SEM) 38 +/- 2 mmHg with placebo to 35 +/- 3 mmHg with nifedipine (p less than 0.01) and during exercise from 63 +/- 4 mmHg with placebo to 51 +/- 3 with nifedipine (p less than 0.01). During hypoxia nifedipine reduced pulmonary vascular resistance index during rest by 27% from 7.84 +/- 0.5 units with placebo to 5.71 +/- 0.6 units with nifedipine (p less than 0.02) and during exercise by 44% from 7.84 +/- 1 units with placebo to 4.37 +/- 1 units with nifedipine (p less than 0.001). Nifedipine when added to low flow oxygen reduced pulmonary vascular resistance index during rest by 16% from 6.15 +/- 0.8 units with oxygen to 5.14 +/- 0.5 units with oxygen plus nifedipine (p less than 0.007) and during exercise by 27% from 5.9 +/- 0.9 units with oxygen to 4.3 +/- 0.7 units with oxygen plus nifedipine (p less than 0.005). On room air nifedipine decreased PaO2 during rest by only 4 +/- 1 mmHg and did not decrease exercise PaO2. During oxygen therapy nifedipine decreased PaO2 during rest by 12 +/- 4 mmHg and during exercise by 8 +/- 3 mmHg. Nifedipine therapy, however, substantially increased oxygen delivery during rest and exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1980

[Myocardial scintigraphy (thallium-201) and electrocardiography at rest and during exercise in angina pectoris. A comparison with coronary angiography (author's transl)].

Ecg (at rest and during exercise) was compared to Thallium-201 myocardial perfusion imaging (at rest and after exercise) in 65 patients with coronary heart disease (myocardial infarction in 53 patients) and angina pectoris. These results were compared to coronary angiography and left ventricular angiography. Group I: (48 patients, comparison of Ecg at rest and Thallium-201 imaging at rest): 33 patients showed agreement of results. In comparison to angiography the 201-Thallium imaging showed less false-negative results than the Ecg as rest. Group II: (23 patients, comparison of Ecg during exercise with Thallium-201 imaging after exercise): 8 patients showed agreement, 15 patients did not. In comparison to angiography the imaging showed better agreement in 20 of 23 patients, the exercise Ecg in 14 of 23 patients. Exercise-Ecg showed false-negative results in 7 patients, Thallium-201 imaging in none. Especially in 1-vessel-disease imaging was superior. Group III: (24 patients, comparison of Ecg at rest and during exercise to 201-Thallium at rest and after exercise): In 19 patients results agreed almost. Because of background-correction imaging is inferior to the Ecg in the apical region. Imaging is superior to the Ecg in the septal and inferior-myocardial regions. Combination of both methods gives best correlations. Sensitivity of Ecg-results is 77% and in imaging 93%.

Adult↗
PubMed1999

A novel mechanism of CD4 lymphocyte depletion involves effects of HIV on resting lymphocytes: induction of lymph node homing and apoptosis upon secondary signaling through homing receptors.

Recently, we reported that abortive HIV infection of resting human T lymphocytes up-regulated expression of CD62L, the receptor for homing to lymph nodes (LNs), and enhanced homing of these cells from the blood into the LNs (Wang et al., 1997, Virology 228:141). This suggested that HIV-induced homing of resting lymphocytes (which comprise >98% of all lymphocytes) may be a major mechanism for the reduction of CD4+ lymphocytes in the blood of infected individuals. This mechanism also could be partially responsible for the lymphadenopathy that often develops at the same time that CD4+ lymphocytes are disappearing from the blood. In this study, we show that secondary signaling through the homing receptors (CD62L, CD44, CD11a) of abortively infected resting CD4+ T lymphocytes induced apoptosis. These signals would occur as the cells home into the LNs. Apoptosis did not occur after secondary signaling through some other receptors (CD26, CD4, CD45, and HLA class I) or in HIV-exposed resting CD8+ lymphocytes signaled through the homing receptors. These findings indicate that HIV-induced homing of resting CD4+ lymphocytes to LNs results in death of many of these cells. This was confirmed in the LNs of SCID mice that were i.v. injected with HIV-exposed resting human lymphocytes. Thus, these effects of HIV upon binding to resting CD4+ T lymphocytes, which are not permissive for HIV replication, may significantly contribute to their depletion in vivo. These findings also offer an explanation for the bystander effect observed in the LNs of AIDS patients, whereby cells not making virus are dying.

Animals↗
PubMed2005

Weight changes and obesity predict impaired resting and endothelium-dependent myocardial blood flow in postmenopausal women.

BACKGROUND: Obesity has been associated with impaired endothelial function, but the influence of lifetime weight patterns on endothelial function has not been studied. HYPOTHESIS: We hypothesized that coronary vascular reactivity would be diminished in postmenopausal women with a history of obesity and frequent weight swings. METHODS: We performed dynamic N-13 ammonia positron emission tomography in 18 postmenopausal women with cardiac risk factors. Myocardial blood flow (MBF) was measured at rest, after the cold pressor test (CPT), and after adenosine infusion in order to determine baseline and endothelium-dependent and -independent flows, respectively. Myocardial blood flow was corrected for cardiac work by normalizing to the rate-pressure product. Weight history was obtained by standardized questionnaire. RESULTS: Normalized rest (n-rest) MBF correlated negatively with current weight (r = -0.52, p = 0.026) and weight at age 18 (r = -0.47, p = 0.047). Normalized CPT (n-CPT) MBF correlated inversely with current weight (r = -0.55, p = 0.018), weight at age 18 (r = -0.605, p = 0.008), and highest weight (r = -0.62, p = 0.006). Higher waist circumference predicted lower n-rest MBF (r = -0.52, p = 0.028) and n-CPT MBF (r = -0.48, p = 0.04). The same association was found with hip circumference (r = -0.52, p = 0.028; r = -0.49, p = 0.038, respectively), whereas higher body mass index (BMI) predicted lower n-CPT MBF (r = -0.53, p = 0.02). Women with at least four significant weight swings had lower MBF during rest, CPT, and n-CPT (0.88 vs. 1.19 ml/g/min, p = 0.008; 0.76 vs. 1.23 ml/g/min, p < 0.001; 0.74 vs. 1.10 ml/g/min, p = 0.009, respectively). CONCLUSIONS: Increased waist and hip circumference, weight, and frequent weight swings are associated with impaired resting and endothelium-dependent MBF in postmenopausal women. These data suggest that lifetime weight patterns may influence cardiovascular risk in women.

Aged↗
PubMed1999

Aerobic exercise and resting blood pressure among women: a meta-analysis.

PURPOSE: The aim of this study was to use the meta-analytic approach to examine the effects of aerobic exercise on resting systolic and diastolic blood pressure among adult women. METHODS: Studies were retrieved from computer searches (MEDLINE, Sport Discus, Current Contents) and bibliographies of retrieved articles were cross-referenced. Inclusion criteria were as follows: (1) randomized trials, (2) aerobic activity as the primary exercise intervention, (3) comparative nonexercise control group included, (4) changes in resting systolic and/or diastolic blood pressure assessed for women ages 18 and older, and (5) studies published in English-language journals between January 1966 and January 1998. The primary outcomes retrieved in this study were changes in resting systolic and diastolic blood pressure calculated as the difference (exercise minus control) of the changes (initial minus final) in these mean values. RESULTS: Ten studies representing 732 subjects and 36 primary outcomes (19 systolic, 17 diastolic) met the criteria for inclusion. Overall, an approximate 2% decrease in resting systolic and 1% decrease in resting diastolic blood pressure were observed (systolic,;x +/- SD = -2 +/- 2.6 mm Hg, 95% bootstrap confidence interval -3 to -1 mm Hg; diastolic,;x +/- SD = -1 +/- 1.9 mm Hg, 95% bootstrap confidence interval -2 to -1 mm Hg). CONCLUSION: Aerobic exercise results in small reductions in resting systolic and diastolic blood pressure among adult women. However, a need exists for additional, well-designed studies on this topic, especially among hypertensive adult women.

Adult↗
PubMed1993

Claudication in the setting of plethysmographic criteria for resting ischemia: is surgery justified?

Objective noninvasive criteria for resting ischemia are sometimes found in patients with milder clinical complaints. If noninvasive information can predict irrevocable progression to resting ischemia, instances of tissue loss theoretically could be prevented by early intervention. Accordingly, we investigated the clinical outcome in 51 claudicators with pulse volume recorder and/or ankle-brachial index (ABI) criteria for ischemia at rest. Patients with type IV (markedly blunted) or type V (flat) ankle or transmetatarsal pulse volume recordings and/or ABI < 0.5 and accompanying claudication were identified. Resting ischemia and/or tissue necrosis developed in 29% of patients and necessitated vascular reconstruction within 36 months. One patient had a primary above-knee amputation at a different institution and 14 patients underwent successful revascularization. In 3 of 14 patients, reconstruction was accompanied by digit or transmetatarsal amputation. No limbs were lost in the revascularized group. Noninvasive criteria for resting ischemia in patients with claudication alone portend a high rate of progression to resting ischemic symptoms. At present the use of clinical criteria and careful follow-up would permit a high rate of foot and limb salvage in those whose ischemia progresses and would prevent unnecessary surgery in the remaining patients. Further prospective definition of patients at risk for progression of ischemia might help prevent tissue loss in selected patients.

Aged↗
PubMed2002

Serial assessment of left ventricular performance at rest and during bicycle exercise by ECG-gated myocardial perfusion SPECT.

UNLABELLED: The present study evaluates left ventricular performance during exercise by ECG-gated myocardial perfusion SPECT with short-time data collection. METHODS: The study population consisted of 10 healthy volunteers (Group N) and 9 patients with ischemic heart disease (Group I). Seven patients in Group I had a history of prior myocardial infarction. Rest ECG-gated SPECT was performed 40 min after an injection of Tc-99m-tetrofosmin (555-740 MBq). After resting data acquisition, Group N underwent up to two 5-min stages of exercise (75 and 125 watts) on a detachable bicycle ergometer. The Group I patients all underwent symptom-limited, maximal testing on the ergometer. ECG-gated SPECT data were acquired from both groups for 3 min at rest and during the last 3 min of each exercise stage. RESULTS: Significant increases occurred in LVEF from rest to peak stress in both groups (from 55.4 +/- 5.8 to 66.6 +/- 4.1% in group N, p < 0.0001; from 49.0 +/- 12.8 to 56.7 +/- 13.8% in Group I, p < 0.001). The LVESV values significantly decreased to peak stress in Group N (from 49.9 +/- 13.1 to 37.8 +/- 10.0 ml, p < 0.0001), whereas LVEDV did not change (from 110.6 +/- 18.9 to 112.0 +/- 19.0 ml). In contrast, the LVESV values at rest and under peak stress were similar in Group I (from 52.6 +/- 23.9 to 51.7 +/- 31.4 ml) and LVEDV in Group I at peak exercise tended to increase (from 102.8 +/- 36.7 to 111.3 +/- 39.0 ml). The changes in LVESV from rest to peak stress were significantly different between Groups N and I (-12.1 +/- 6.3 vs. -0.9 +/- 11.6 ml, p < 0.02). CONCLUSION: ECG-gated SPECT with short-time data collection can assess left ventricular function during exercise and may offer useful information for evaluating patients with ischemic heart disease.

Adult↗
PubMed2003

Dobutamine Tc-99m furifosmin SPECT in detection of coronary artery disease: evaluation of same day, rest-stress protocol.

The purpose of this study was to evaluate the feasibility and diagnostic accuracy of same day rest-stress myocardial perfusion SPECT (MP SPECT) protocol by using technetium-99m (Tc-99m) furifosmin in conjunction with dobutamine stress test in subjects in whom coronary artery disease (CAD) had been proven or excluded at coronary angiography (CA). The study group consisted of 25 patients (8 female and 17 male with a mean age of 53.04 +/- 8.56 yrs) unable to perform treadmill exercise or unsuitable for pharmacologic vasodilator stress testing. Ten mCi (370 MBq) of Tc-99m furifosmin was injected intravenously at rest. Sixty min after injection, planar and SPECT images were acquired. One hour later all patients underwent dobutamine stress test. At the peak stress, 20 mCi (740 MBq) of Tc-99m furifosmin was injected. Sixty min after stress dose injection, planar and SPECT images were acquired. Rest-stress planar and SPECT data were evaluated by using visual and quantitative analysis. Heart to adjacent organ (Heart/Lung; H/Lu and Heart/Liver; H/Li) activity ratios were calculated from anterior planar images by using regions of interest (ROI). SPECT data were interpreted by using 20 segment-5 point scoring system from short axis and vertical long axis slices. The results of rest-dobutamine stress Tc-99m furifosmin MP SPECT were compared with CA results. There were statistically significant differences between H/Lu and H/Li ratios at rest and stress conditions. Heart/adjacent organ activity ratios were similar and significant statistical difference could not be found between CA positive and CA normal patients. Sensitivity, specificity and accuracy for Tc-99m furifosmin SPECT study were calculated as 90%, 80% and 84% for left anterior descending (LAD), 87%, 94% and 92% for left circumflex (LCx) and 67%, 86% and 80% for right coronary artery (RCA), respectively. Overall sensitivity, specificity and accuracy were calculated as 83%, 87% and 85%, respectively. According to the results obtained in this study, it may be concluded that same day rest-dobutamine stress Tc-99m furifosmin SPECT protocol is a feasible and accurate technique in the evaluation of CAD, especially in patients unable to perform treadmill exercise or unsuitable for pharmacologic vasodilator stress testing.

Adult↗
PubMed2003

Torque loss induced by repetitive maximal eccentric contractions is marginally influenced by work-to-rest ratio.

The influence of different work-to-rest (W:R) ratios during fatigue induced by maximal eccentric contractions is unknown. The present study sought to expand the understanding of the task-dependent nature of eccentric contractions, and the associated fatigue, during exercise and acute as well as extended recovery periods. Using a Biodex multi-joint dynamometer, the ankle dorsiflexors of eight men [26 (4) years] were fatigued with 150 maximal eccentric contractions. Set structure was manipulated such that one leg performed 3 sets of 50 repetitions (short rest protocol, SRP), and the other leg performed 15 sets of 10 repetitions (long rest protocol, LRP). A 1-min rest interval separated each set, which resulted in 2 and 14 min of total rest for the SRP and the LRP, respectively. At fatigue, the SRP demonstrated a marginally greater loss of average peak eccentric torque than the LRP ( P<0.05). In the acute period following fatigue, isometric peak torque loss and the degree of low-frequency fatigue (LFF) were not recovered ( P<0.05) and were equivalent for both protocols. Significant impairment of both eccentric and isometric torque was persistent and equal for each protocol at 96 h of recovery ( P<0.05). These findings suggest that the W:R ratio has a modest influence on the fatigue (torque loss) induced by maximal eccentric contractions, but maximal isometric torque during recovery and LFF are insensitive to changes in total rest time.

Adaptation, Physiological↗
PubMed2003

Changes in bone turnover markers during 14-day 6 degrees head-down bed rest.

Osteoporosis caused by exposure to microgravity represents a serious clinical concern, but the mechanisms have yet to be fully elucidated. The present research aimed to elucidate the effects of microgravity environments on bone turnover, with a specific focus on changes in bone resorption markers such as type I collagen cross-linked N-telopeptides (NTx) and deoxypyridinoline (Dpyr), for which scant data are available regarding detailed time course. Methods using 6 degrees head-down bed rest were utilized to simulate a microgravity environment. Eleven adult male volunteers underwent 6 degrees head-down bed rest for 14 days; measurements were made of serum and urine Ca concentrations, in addition to osteocalcin (OC), bone alkaline phosphatase (ALP), NTx, and Dpyr as bone turnover markers. By the end of bed rest, concentrations of bone ALP had significantly increased, but OC displayed a tendency toward decrease. Concentrations of Dpyr significantly increased from day 6, remaining elevated until the end of bed rest. Concentrations of NTx significantly increased on day 13 and at the end of bed rest. Serum and urinary concentrations of Ca increased significantly at the end of bed rest. Bone ALP represents a relatively early marker of osteoblast differentiation at the matrix maturation phase and OC is a late marker in osteoblast differentiation at the calcification phase. The present results therefore suggest an absolute increase in bone resorption and normal or reduced bone formation, together causing prominent uncoupling and rapid bone loss after simulated microgravity. Moreover, the present results suggest that bone resorption is enhanced at an early stage of exposure to microgravity environments.

Adult↗
PubMed2005

Comparison of impedance cardiography and thermodilution-derived measurements of stroke volume and cardiac output at rest and during exercise testing.

BACKGROUND: Non-invasive evaluation of haemodynamic variables remains a preferable and attractive option in both pharmacologic research and clinical cardiology. OBJECTIVES: The objective of this study was to evaluate the correlation, feasibility and diagnostic value of haemodynamic measurements by ICG with the thermodilution (TD) method at rest and during exercise testing. METHODS: We measured stroke volume (SV) and cardiac output (CO) with both methods in 20 patients with suspected coronary artery disease (CAD). All measurements were performed simultaneously at rest and during bicycle exercise. RESULTS: There was a highly significant correlation (p < 0.001) for measurements of SV between both methods at rest (r = 0.83) and during exercise (r = 0.85-0.87) with 50-100 watts. For measurements of CO, the respective correlations were r = 0.85 at rest and r = 0.92-0.94 during exercise. The mean difference for measurements of SV were 3.8 +/- 12.6 ml at rest and 6.5+/- 11.4 ml during exercise. For measurements of CO, the mean difference between both methods was 0.9 +/- 1.0 l/min at rest and 1.0+/- 0.8 l/min during exercise. Compared to TD measurements, ICG had a bias to overestimate SV and CO of approximately by 5-10%. One patient had to be excluded because of inappropriate quality of the ICG signals during exercise. CONCLUSIONS: ICG is a feasible and accurate method for non-invasive measurements of SV and CO. Haemodynamic measurements by ICG were correlated highly significant to simultaneous measurements by the TD method.

Aged↗
PubMed1982

Relationship of exercise capacity to resting left ventricular performance and basal plasma norepinephrine levels in patients with congestive heart failure.

Seventeen patients with chronic congestive heart failure (CHF) were studied to assess the relationship of resting left ventricular function, as measured by noninvasive and invasive methods, to maximal exercise capacity, as measured by peak total body oxygen consumption (VO2). Supine basal plasma norepinephrine (NE) was also measured to evaluate its relationship to the severity of heart failure and to determine whether it may be a better predictor of exercise capacity in patients with CHF than the more commonly employed noninvasive and invasive tests of left ventricular function. Fourteen of the 17 patients underwent upright bicycle exercise (average peak VO2 10.60 +/- 1.40 ml/kg/min, +/- SEM) to their symptomatic maximum. There was no significant correlation between peak VO2 and the noninvasive measurements of left ventricular performance obtained at rest, including cardiothoracic ratio, left ventricular internal dimension by M-mode echo, percent shortening of the minor axis by M-mode echo, and radionuclide ejection fraction. Hemodynamic measurements were performed in 16 patients. The hemodynamic measurements at rest also failed to correlate with exercise capacity. The supine basal plasma NE, which was elevated in these 17 patients (612 +/- 100 pg/ml), had an inverse relationship with stroke work index (r - -0.70, p less than 0.01) and stroke index (r = -0.83, p less than 0.001) and a positive correlation with right atrial pressure (r = 0.81, p less than 0.001). Although both noninvasive and invasive measurements at rest failed to correlate significantly with peak VO2 during exercise, the plasma NE had a significant inverse correlation with peak exercise VO2 (r = -0.50, p less than 0.05). The basal supine plasma NE is therefore elevated in patients with CHF, is a marker for the severity of CHF as measured by hemodynamics performed at rest, and is a better predictor of exercise capacity than standard noninvasive and invasive tests performed at rest.

Adult↗
PubMed1985

Frequency of intracoronary filling defects by angiography in angina pectoris at rest.

Recent studies have shown that pain at rest in patients with unstable angina pectoris is often caused by transient reduction in regional myocardial perfusion. Coronary spasm has been implicated as a mechanism of this phenomenon. Recent reports have documented the occurrence of intracoronary thrombus in patients with unstable angina. Previous surveys have estimated a 6 to 12% frequency of intracoronary thrombus in this syndrome, but have not examined whether this incidence is related to how recent the angina at rest was. Angiograms of 119 patients with unstable angina who had rest pain within 14 days of angiography and 35 patients with stable angina were surveyed. Patients with unstable angina were subgrouped according to how recent angina at rest was at the time of angiography. Group I consisted of 44 patients in whom rest pain occurred within 24 hours before angiography. The 75 patients in group II had angina at rest between 1 and 14 days before angiography. Patients in group II had stable angina. The angiographic criterion for intracoronary thrombus was an intraluminal filling defect, surrounded by contrast medium on 3 sides, located just distal to or within a coronary stenosis, as assessed by each of 2 independent observers blinded to the nature of the anginal syndrome and its temporal proximity. Intracoronary thrombi were found in 44 of 119 patients with unstable angina (37%) and 0 of 35 patients with stable angina (p less than 0.00002). Intracoronary thrombi were found in 23 of 44 patients (52%) in group I and 21 of 75 (28%) in group II (p less than 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Influence of beta blockade and intrinsic sympathomimetic activity on hemodynamics, inotropy and respiration at rest and during exercise.

The degree of intrinsic sympathomimetic activity (ISA) is reported to influence the effects of beta blockade at rest, but the effects during exercise are not well documented. Heart rate, blood pressure and left ventricular (LV) function (as assessed by systolic time intervals) were measured at rest and during upright bicycle exercise as well as with flow-volume spirometry at rest in 13 healthy volunteers. The measurements were performed before and 4 and 24 hours after a single oral dose of pindolol (10 mg), nadolol (80 mg) and acebutolol (400 mg) in a double-blind, randomized, crossover manner. All drugs reduced heart rate, but nadolol had the most pronounced and longest bradycardic effect at rest. Diastolic blood pressure was only slightly influenced by the drugs, whereas systolic pressure was significantly lower compared with control values, especially during exercise (p less than 0.001). Neither preejection period (PEP) nor LV ejection time (LVETc) was changed at rest after pindolol, but PEP increased and LVETc decreased significantly after nadolol (p less than 0.05 for PEP and p less than 0.01 for LVETc) and acebutolol (p less than 0.05 for both). During exercise, PEP and LVET were significantly longer after all 3 drugs compared with control values. Only nadolol, which lacks ISA, significantly decreased expiratory flow values (p less than 0.05). Thus, unlike the other beta blockers, pindolol (with strong ISA) did not depress LV function at rest, while during exercise all 3 beta blockers had equal adverse effects. The degree of ISA appears to be important in determining the hemodynamic effects of beta-blocking drugs.

Acebutolol↗
PubMed1988

Blood pressure at rest and during maximal dynamic and isometric exercise as predictors of systemic hypertension.

This study sought to verify evidence that transient high blood pressure (BP) at rest and during dynamic and isometric exercise is often predictive of later hypertension. In addition these 3 predictors were compared. One hundred office patients (all men) with BPs less than 140/90 mm Hg, ages 28 to 79 years, who had little or no heart disease and were not taking medication, had BPs taken at rest and during treadmill and handgrip dynamometer. Within 14 years, 16 subjects developed hypertension and 84 remained normotensive. Multivariate statistical comparisons for systolic and diastolic BPs and their interactions were used to discriminate between later hypertensive and normotensive subjects. The best single predictor was resting diastolic BP, classifying 88% of hypertensive and 69% of normotensive subjects correctly, followed closely by handgrip and treadmill diastolic BP and resting, treadmill and handgrip systolic BP. The best prediction was by the interaction between resting diastolic BP X handgrip diastolic BP; this classified 88% of hypertensive and 80% of normotensive subjects correctly. Of the few known precursors of hypertension, high BP at rest and during dynamic and isometric stress provides a means of alerting to careful follow-up and early treatment.

Adult↗
PubMed1983

Function of the hypertrophied left ventricle at rest and during exercise. Hypertension and aortic stenosis.

Assessment of left ventricular function may be of value in patients with pressure-loaded, hypertrophied left ventricles for the purpose of characterizing such patients as to prognostic risk. To determine whether left ventricular function is in part independent of loading stresses in such patients, and to assess the effects of removal of loading factors, we have reviewed preliminary data in 60 patients with essential hypertension and in 26 patients with aortic stenosis who were studied with radionuclide cineangiography. Patients with hypertension manifested a poor but statistically significant direct relationship between systolic arterial pressure and left ventricular ejection fraction at rest, and a poor but significant inverse relationship between systolic pressure and the magnitude of change in ejection fraction from rest to exercise. However, a strong correlation existed between echocardiographic systolic fractional shortening and end-systolic wall stress at rest. Nonetheless, many patients with normal fractional shortening-end-systolic wall stress relationships had subnormal ejection fraction responses during exercise; the two patients with subnormal fractional shortening-end-systolic wall stress relationships at rest also had subnormal fractional shortening-end-systolic wall stress relationships during exercise. Arterial pressure alone was not predictive of these functional responses. These data suggest that hypertensive patients can be categorized on the basis of left ventricular function at rest and during exercise, independent of arterial pressure. Among patients with aortic stenosis, ejection fraction at rest averaged 67 percent before valve replacement (normal = 57 percent, p less than 0.01), and changed little after operation (71 percent, not significant). However, potential functional benefits of afterload reduction in the patient with the chronically pressure-loaded, hypertrophied left ventricle was suggested by results during exercise: before surgery the ejection fraction during exercise averaged 56 percent (normal = 71 percent, p less than 0.01), but after valve replacement it rose to 72 percent (not significant versus normal). Thus, our data in patients with aortic stenosis supplement our data in patients with hypertension, indicating that myocardial functional improvement can be achieved by unloading therapy in patients with long-standing left ventricular pressure-loading and hypertrophy.

Adult↗
PubMed1992

Postprandial thermogenesis at rest and postexercise before and after physical training in lean, obese, and mildly diabetic men.

To determine the independent impact of physical training on postprandial thermogenesis at rest and after 1 hour of cycling at 100 W, 10 lean (15% +/- 1% body fat), 10 obese (33% +/- 2% fat), and six obese diet-controlled, type II diabetic men (34% +/- 4% fat) underwent 12 weeks of vigorous cycle ergometer training (4 h/wk at approximately 70% of maximum oxygen consumption [VO2max]) while maintaining body weight and composition. Body weight was held constant by refeeding the energy expended in each training session. Cardiorespiratory fitness increased by approximately 27%, but body weight and fat did not change. Before and at least 4 days after the last exercise session, energy expenditure was measured for 3 hours under four conditions: (1) rest, no meal; (2) rest, after a 720-kcal mixed meal; (3) postexercise after 1 hour cycling, no meal; and (4) postexercise, meal after exercise. The thermic effect of food was calculated as postprandial minus postabsorptive energy expenditure at rest and postexercise (kcal/3 h). Before and after training, the thermic effect of food during rest was lower in obese than in lean men, and lower in diabetic than in obese men (P less than .05). Thermogenesis was improved after short-term exercise in obese and diabetic men compared with that at rest, but was not normalized (P less than .05 for lean v obese, diabetic men). A significant effect of training on thermogenesis was due to a small but significant increase after training for diabetic men under the postexercise condition. Thus, while short-term exercise enhances but does not normalize thermogenesis in obese and diabetic men, long-term exercise training leading to increased cardiorespiratory fitness, in the absence of changes in body composition, leads to a small increase in thermogenesis in diabetic men, which manifests only after a short period of exercise.

Adult↗
PubMed1993

Separate acquisition rest thallium-201/stress technetium-99m sestamibi dual-isotope myocardial perfusion single-photon emission computed tomography: a clinical validation study.

OBJECTIVES: This study assessed the validity of a novel approach to myocardial perfusion scintigraphy that provides the opportunity to avoid the drawbacks of standard same-day rest/stress technetium-99m sestamibi myocardial perfusion studies by using separate-acquisition dual-isotope rest thallium-201 and exercise technetium-99m sestamibi single-photon emission computed tomography (SPECT). BACKGROUND: Standard same-day rest/stress technetium-99m sestamibi myocardial perfusion studies are cumbersome, associated with a potential decrease in perceived stress defect severity compared with thallium-201 due to the presence of rest technetium-99m sestamibi and may be unable to differentiate hibernating from infarcted myocardium. METHODS: The dual-isotope procedure was performed in 63 patients without previous myocardial infarction undergoing coronary angiography to evaluate sensitivity and specificity for coronary artery disease and in 107 patients with a low (< 5%) likelihood of coronary artery disease to evaluate normalcy rate. To validate defect reversibility, the dual-isotope SPECT study was compared with stress/rest technetium-99m sestamibi SPECT studies in a separate group of 31 patients with previous documented myocardial infarction who underwent a rest technetium-99m sestamibi study in addition to the dual-isotope SPECT study. RESULTS: In angiographic correlations, dual-isotope SPECT demonstrated high sensitivity for detecting patients with > or = 50% stenosis (91%, 55 patients) and > or = 70% stenosis (96%, 52 patients). In a small group of patients, high specificity was also observed (75% for < 50% stenosis [8 patients] and 82% for < 70% stenosis [11 patients]). A very high normalcy rate of 95% was also found. In the patient group assessed for defect reversibility, in zones with no previous myocardial infarction, segmental agreement for defect type between rest thallium-201 and rest technetium-99m sestamibi studies was 97% (kappa = 0.79, p < 0.001). In myocardial infarct zones, segmental agreement for defect type was 98% (kappa = 0.93, p < 0.001). Image quality was generally good to excellent. CONCLUSIONS: Our findings demonstrate that separate-acquisition dual-isotope myocardial perfusion SPECT is accurate for coronary artery disease detection, correlates well with rest-stress sestamibi studies for assessment of defect reversibility and results in good to excellent image quality. This approach provides an excellent method for the combined assessment of stress myocardial perfusion and myocardial viability.

Aged↗