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Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sick preterm infants may, under certain conditions, demonstrate blood pressure passive cerebral blood flow in response to changes in arterial carbon dioxide tension. Blood pressure in turn depends on cardiac output and peripheral resistance. A Doppler technique for assessing cardiac output compared favourably in terms of reproducibility to a thermodilution technique in a group of infants undergoing cardiac catheterization for congenital heart disease. Doppler was subsequently used to monitor changes in cardiac output following an increase in arterial carbon dioxide tension of 1 kPa in 25 ventilated preterm infants. Blood pressure increased significantly (p = 0.006). However, heart rate did not change significantly (p = 0.16) and, in addition, both stroke and minute volume decreased (p = 0.023, p = 0.02, respectively). This suggests that accompanying changes in components of peripheral resistance exert important effects on blood pressure in the preterm neonate in response to changes in arterial carbon dioxide tension.
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PMID:Cardiovascular effects of carbon dioxide in ventilated preterm infants. 139 61

To determine whether patients with heart disease depend more than normal subjects on anaerobic metabolism to perform the same level of exercise, the anaerobic threshold, slope of the increase in carbon dioxide output with respect to oxygen uptake (delta VCO2/delta VO2) and the slope of the increase in oxygen uptake with respect to the increase in work rate (delta VO2/delta WR) both below and above the anaerobic threshold during exercise were evaluated. A total of 106 patients with chronic heart disease and 42 healthy subjects performed a symptom-limited incremental exercise test in a ramp pattern on a cycle ergometer. Peak oxygen uptake was significantly lower in the patients with heart disease than in the normal subjects. The anaerobic threshold, which was 20 +/- 4.6 ml/min per kg in normal subjects, decreased significantly with progressing severity of functional class: 16 +/- 2.4, 14.1 +/- 2.5 and 11.3 +/- 1.5 ml/min per kg, respectively, in patients in class I, class II and class III. The slope of delta VO2/delta WR, which represents the degree of aerobic metabolism, was also decreased both below and above the anaerobic threshold with increasing severity of heart disease. delta VCO2/delta VO2 below the anaerobic threshold was approximately 0.9 (p = NS between normal subjects and patients). However, delta VCO2/delta VO2 above the anaerobic threshold became steeper with increasing severity of heart disease: 1.37 +/- 0.17 in normal subjects versus 1.55 +/- 0.24, 1.67 +/- 0.3 and 1.8 +/- 0.35 respectively, in patients in functional class I, class II and class III.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Anaerobic metabolism as an indicator of aerobic function during exercise in cardiac patients. 160 12

To evaluate the effects of different methods of detection, exercise modes, protocols, and reviewers on oxygen uptake (VO2) at the ventilatory threshold (ATge), 17 men with heart disease (mean age 59 +/- 6 years) and six healthy men (mean age 60 +/- 11 years) underwent six exercise tests on different days. Each subject performed three treadmill tests (Bruce, Balke, and ramp) and three bicycle ergometer tests (50 W/stage, 25 W/stage, and ramp) in random order. The ventilatory threshold was determined for each of the six exercise tests by three independent, blinded reviewers by means of graphic plots of three commonly used methods of determination: (1) changes in the ventilatory equivalents for VO2 and VCO2, (2) changes in end-tidal oxygen and carbon dioxide pressures, and (3) the intersection of the slope of VCO2 and VO2 (V slope). The largest variability in the ATge was observed with changes in the exercise protocol. The greatest absolute (ml/min) and percentage differences in oxygen uptake at the ATge as a result of changes in protocol, method of determination, and observers were 336 (36%), 125 (12%), and 70 (7%), respectively. The overall intraclass correlation coefficient for VO2 at the ATge among the three reviewers was 0.60 and among the three protocols was 0.85 (p less than 0.01). The V slope method of detection had consistently good agreement among reviewers and was least affected by the protocol. The variance in the ATge (excluding intersubject and error variance) accounted for by differences in protocol, method, and reviewer was 82%, 14%, and 4%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The ventilatory threshold: method, protocol, and evaluator agreement. 185 34

Orthotopic heart transplantation (OHT) represents an effective alternative for individuals with end-stage heart disease. The current literature reports only the responses of OHT patients to greater than or equal to 4 mo of exercise training (ET) and frequently lacks adequate controls. Most programs currently treating OHT patients usually provide 6-12 wk of ET. This study describes the effects of a 10-wk supervised ET program in 12 male OHT patients and 5 other male OHT patients who served as a comparison group. Graded exercise tests were performed before and after ET. After ET, maximal O2 consumption was significantly greater for the ET group than the comparison group (P less than 0.05) and the mean increase in peak heart rate was 18 +/- 4 and 6 +/- 4 (SE) min-1 for ET and comparison groups, respectively (P less than 0.05). Maximal ventilation was also significantly greater for the ET group at after ET, while resting heart rate and blood pressure and peak blood pressure, O2 pulse, respiratory rate, and ventilatory equivalents for O2 and CO2 were not significantly changed. We conclude that after OHT a 10-wk ET program improves maximal O2 consumption and, by improving peak heart rate, improves O2 delivery.
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PMID:Cardiovascular responses of heart transplant patients to exercise training. 188 57

In right-to-left (RL) intracardiac shunting, the venous blood that is added to the oxygenated blood in the left heart is both poor in oxygen and rich in carbon dioxide. Thus, any given degree of arterial desaturation is associated with an obligatory arterial to end-tidal carbon dioxide tension difference (PaCO2--PETCO2). This paper presents a theoretical analysis of the relationship between PaCO2-PETCO2 and arterial hemoglobin saturation (SaO2) in cyanotic heart disease. Using the shunt equation as a starting point, a curvilinear, negative correlation between PaCO2-PETCO2 and SaO2 can be demonstrated. The slope of the regression of PaCO2--PETCO2 against SaO2 is shown to be positively correlated to Hb concentration, PaCO2, and the respiratory quotient R. The slope of the regression is also slightly increased at relatively high SaO2s and at high inspired oxygen fractions, although these latter factors are of lesser significance. However, in addition to the above primary effects of RL shunting, secondary effects may occur if pulmonary perfusion is reduced sufficiently to cause "alveolar hypoperfusion," which also creates an alveolar dead space. Primary and secondary effects are additive. This theoretical analysis is illustrated with a study of 27 children with congenital heart disease. Their lungs were ventilated with a Servoventilator 900 C, and carbon dioxide single-breath tests were obtained on-line with the use of a computerized system based on the Siemens-Elema carbon dioxide analyzer 930. Blood was sampled for PaCO2 measurement and arterial Hb saturation was measured by pulse oximetry (SpO2).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The relationship between the arterial to end-tidal PCO2 difference and hemoglobin saturation in patients with congenital heart disease. 190 12

905 diagnostic contrast echocardiographic studies (DCE) were performed on 223 children. Carbon dioxide microbubble was used as contrast agent in various age groups, especially in newborns and infants because of its safety in application, stable contrast effect, and peripheral vein injection. Two-dimensional echocardiography (2-DCE), a useful tool in diagnosis of left to right shunt lesions reduced false negative diagnoses for ventricular septal defects and eliminated false positive diagnosis for atrial septal defects and patent ductus arteriosus. The accuracy of diagnosis in this series was 97%. The results of this series showed that 2-DCE is also valuable in the diagnosis of congenital heart disease with right to left shunts, and can be used to evaluate shunt levels and determine the obstructive sites on the right side of the heart.
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PMID:Diagnostic contrast echocardiography in children with congenital heart disease. 217 82

Respiratory failure accompanied by cardiac failure occurs mostly due to decreased PaO2. However, sometimes we encounter patients with cardiac failure having on increase of PaCO2, who develop CO2 narcosis in the ICU. In this study we evaluated hypoventilation respiratory failure in patients with cardiac failure. Seventy-six patients with both respiratory failure and cardiac failure caused by intrinsic heart disease, who required mechanical ventilation in the ICU were studied. The patients were divided into 2 groups; hypoxic respiratory failure group (n = 53) and hypoventilation respiratory failure group (n = 23). Blood gas analysis and cardiovascular hemodynamics including arterial blood pressure, heart rate and Swan-Ganz catheter findings were performed before, during and after mechanical ventilation in each patient. Mortality rate and its relation to hemodynamic variables were also evaluated in each group. In both groups even when it was possible to maintain oxygenation capacity by conducting mechanical ventilation against severe respiratory failure, what can be said about the prognosis is that it depended totally on the improvement of cardiac function. The mechanism by which hypoxemia is displayed due to cardiogenic pulmonary edema is already well known, but in regard to the mechanism of hypercapnia in cases with hypersensitivity of the airways it is thought that through induction of cardiogenic pulmonary edema bronchial spasms is induced, and this causes hypercapnia. However, it is also possible to consider cardiac asthma as the cause. Among respiratory failure cases due to cardiogenic pulmonary edema that occurs in association with heart failure, there is both hypoxic respiratory failure as well as hypoventilation respiratory failure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Study on the respiratory failure with cardiac failure--focus on hypoventilation respiratory failure]. 221 87

Deadspace is defined in terms of the efficiency of the lung in eliminating carbon dioxide. The airway deadspace is the volume of the airway in which gas moves chiefly by convection. The alveolar deadspace is caused by ventilation/perfusion inequalities at the alveolar level. The commonest causes of increased alveolar deadspace are airways disease--smoking, bronchitis, emphysema, and asthma. Other causes include pulmonary embolism, pulmonary hypotension, and ARDS. In addition, right-to-left shunting (cyanotic heart disease, atelectasis) causes an apparent or virtual deadspace, which, although not representing non-perfusion of any compartment, nevertheless reduces the efficiency of ventilation.
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PMID:Deadspace during anaesthesia. 229 89

The ability to assess changes in pulmonary blood flow, using a modified Qp/Qs ratio (Qp/Qsmod), was evaluated in 12 infants with congenital heart disease and complete intracardiac mixing who underwent modified Blalock-Taussig shunt procedures. At the various measuring stages there were no major changes in mean arterial pressure or heart rate. Arterial oxygen tensions and saturation increased (P less than 0.01) and the arterial to end-tidal carbon dioxide difference (PaCO2-PE'CO2) was significantly reduced (P less than 0.001) after completion of the shunt procedure. There was a significant increase in mean Qp/Qsmod after chest closure (P less than 0.001), which was seen to correlate well with early clinical outcome. Two patients who did not demonstrate any increase in Qp/Qsmod over the course of the procedure had failed shunts. The limitations of use of the Qp/Qsmod are discussed. A modified Qp/Qs ratio of less than unity after surgery is strongly indicative of inadequate palliation.
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PMID:Pulmonary blood flow during closed heart surgery. Use of a modified Qp/Qs ratio to assess adequacy of palliation of systemic-pulmonary artery shunts. 245 89

The authors investigated the effect of occupational exposure to carbon monoxide on mortality from heart disease in a retrospective study of 5,529 New York City bridge and tunnel officers employed between January 1, 1952 and February 10, 1981, at any one of nine major water crossings operated by the Triborough Bridge and Tunnel Authority of New York City. Among former tunnel officers, 61 deaths from arteriosclerotic heart disease were observed, as compared with 45 expected (standardized mortality ratio = 1.35, 90% confidence interval 1.09-1.68); expected rates were based on the New York City population. Using a proportional hazards model, the authors compared the risk of mortality from arteriosclerotic heart disease among tunnel officers with that of the less-exposed bridge officers. No association of arteriosclerotic heart disease with length of exposure was observed, but there was significant interaction of exposure with age. The elevated risk of arteriosclerotic heart disease among tunnel officers, as compared with that of bridge officers, declined after cessation of exposure, with much of the risk dissipating within as little as five years. The parallel findings of this study of occupational exposure to carbon monoxide and those studies showing the relation of cigarette smoking to cardiovascular mortality suggest that carbon monoxide may play an important role in the pathophysiology of cardiovascular mortality associated with cigarette smoking.
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PMID:Heart disease mortality among bridge and tunnel officers exposed to carbon monoxide. 246 56


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