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C W Barlow

Publications and source records attributed to C W Barlow.

At least 19 recordsLinked to original sources
PubMed2006

Emergency intensive care admission following elective thoracic surgery.

AIM: The aim of this study was to analyse the outcomes of patients admitted to the intensive care unit (ICU) following initial recovery after elective thoracic surgery. METHODS: The case notes of all patients who underwent elective thoracic surgery over a one-year period were reviewed. Patients who were admitted to ICU following an initial recovery on the ward were identified and their postoperative course analysed. The clinical and demographic characteristics of these patients were recorded and their outcomes analysed. RESULTS: A total of 20 patients were admitted to ICU of whom 13 (65%) were admitted for respiratory complication, 5 with sepsis and 2 with cardiovascular instability. Sixteen (80%) patients required CPAP or BIPAP, of whom only 7 (35%) required mechanical ventilation. Renal support was required in 7 patients, with 2 (10%) requiring haemofiltration. ICU survival was 15 patients (75%), whilst overall three-month survival post ICU admission was 65%. Requirement for renal support was the only predictor of mortality on univariate and multivariate analysis. CONCLUSIONS: Salvage ICU admission following elective thoracic surgery is associated with significant mortality, however the outcome is far from hopeless. The majority of patients can be managed without recourse to mechanical ventilation or haemofiltration. The need for renal support is, however, a significant adverse prognostic indicator.

Aged↗
PubMed2001

Influence of atrial fibrillation on outcome following mitral valve repair.

BACKGROUND: To investigate the outcome of patients in atrial fibrillation (AF) following mitral valve repair, clinical and echocardiographic follow-up was undertaken in 400 consecutive patients who underwent mitral valvuloplasty from 1987 to 1999. METHODS AND RESULTS: The main indications for surgery were degenerative (81.4%), endocarditis (7.1%), rheumatic (6.6%), ischemic (4.6%), and traumatic (0.3%) mitral valve disease. After excluding 6 paced patients and 1 patient in nodal rhythm, we compared the outcomes of 152 patients in AF against 241 patients in sinus rhythm. For patients in AF versus those in sinus rhythm, more AF patients were older (mean age 67.2+/-8.8 versus 61.9+/-11.8 years, respectively; P<0.001), more were assigned to a poorer New York Heart Association (NYHA) class (77.6% versus 66.0% in NYHA III/IV, respectively; P=0.01), and more demonstrated impaired ventricular function (78.9% versus 46.2% with moderate or severe impairment, respectively; P<0.001). For patients in AF versus those in sinus rhythm, there was no difference in 30-day mortality (2.0% versus 2.1%, respectively; P=0.95), repair failure (5.4% versus 3.6%, respectively; P=0.41), stroke (5.4% versus 2.2%, respectively; P=0.11), or endocarditis (2.3% versus 0.9%, respectively; P=0.27) on follow-up at a median of 2.8 years (interquartile range 1.1 to 6.0). On echocardiography, the proportion of patients with mild regurgitation or worse was 13.3% (AF patients) versus 10.8% (patients in sinus rhythm) (P=0.70). Patients in AF versus those in sinus rhythm had lower survival at 3 years (83% versus 93%, respectively) and 5 years (73% versus 88%, respectively). Univariate analysis identified factors affecting survival as AF (P=0.002), age >70 years (P=0.041), and poor ventricular function (P<0.001). However, by use of a multivariate model, only poor ventricular function remained significant (P=0.01). CONCLUSIONS: AF does not affect early outcome or durability of mitral repair. The onset of AF may be indicative of disease progression because of its association with poor left ventricular function.

Aged↗
PubMed2001

Rabbit antithymocyte globulin versus OKT3 induction therapy after heart-lung and lung transplantation: effect on survival, rejection, infection, and obliterative bronchiolitis.

The superiority of different induction therapies after heart-lung and lung transplantation is not clearly established; specifically, whether monoclonal (OKT3) or polyclonal antibody induction therapy provides any advantage. Between 1989 and 1991 we used induction therapy with either rabbit antithymocyte globulin (RATG) or OKT3, given at random based on the availability of RATG. RATG was used in 25 patients (RATG group 1) and OKT3 in 38 patients (OKT3 group 1). Early results suggested a survival advantage with RATG. From 1992 until 1997 we used RATG induction therapy in 108 patients (RATG group 2). This study analyzed longer-term survival, infection, rejection, and obliterative bronchiolitis (OB) rates for RATG group 1 and OKT3 group 1 and assessed outcomes for RATG group 2. The 1-, 3-, and 5-year survival for RATG group 1 was 72 %, 72 %, and 52 % and for OKT3 group 1 was 63 %, 49 %, and 34 % (P < 0.05). The 1- and 3-year survival for RATG group 2 was 84 % and 74 %. The 1-, 3-, and 5-year actuarial freedom rates from lung rejection for RATG group 1 were 38 %, 38 %, and 31 % and for OKT3 group 1 were 21 %, 0 %, and 0 % (P < 0.01). The linearized rate (events/100 patient days) of all infections at 3 months was 1.55 +/- 0.28 for RATG group 1 and 2.19 +/- 0.27 for OKT3 group 1 (P = NS). The infection rate for RATG group 2 was 1.60 +/- 0.13. The actuarial rates of freedom from OB at 1, 3, and 5 years for RATG group 1 were 84 %, 51 %, and 45 % and for OKT3 group 1 were 77 %, 61 %, and 36 % (P = NS), while for RATG group 2 the rates were 97 % and 92 % at 1 and 3 years (P < 0.01 vs RATG group 1 and OKT3 group 1). The use of RATG induction therapy from 1989 through 1991 resulted in improved actuarial survival and less rejection, without increased infection rates. The use of RATG since 1992 has continued to result in similar outcomes for survival, infection, and rejection. The time to onset of OB has improved further in recent years. This may be a result of recent improvements in cytomegalovirus (CMV) prophylaxis.

Adult↗
PubMed2000

Heart-lung versus double-lung transplantation for suppurative lung disease.

OBJECTIVE: The purpose of this study was to compare outcomes after heart-lung or double-lung transplantation in patients undergoing transplantation because of end-stage suppurative lung disease. METHODS: We reviewed our experience in patients with cystic fibrosis or bronchiectasis who had heart-lung or double-lung transplantation between January 1988 and September 1997. Twenty-three patients (14 male, 21 cystic fibrosis) had heart-lung transplantation and 24 patients (8 male, 19 cystic fibrosis) had double-lung transplantation. There were no statistically significant differences between the groups in age, weight, preoperative creatinine level, cytomegalovirus status, maintenance immunosuppression, or donor demographics. Patients received induction therapy with monoclonal (OKT3) or polyclonal (rabbit anti-thymocyte globulin) antibody. RESULTS: Sixteen of 24 patients had double-lung transplantation after 1994 whereas 13 of 22 patients had heart-lung transplantation before 1991, allowing longer follow-up for the heart-lung group. Mean waiting times for transplantation were 270 +/- 245 days (heart-lung) and 361 +/- 229 days (double-lung; P =.20). The 1-, 3-, and 5-year actuarial survival figures were respectively 86%, 82%, and 65% (heart-lung) and 96%, 75%, and unavailable (double-lung; P = no significant difference). The 1-, 3-, and 5-year rates of freedom from obliterative bronchiolitis were respectively 77%, 61%, and 45% (heart-lung) and 86%, 78%, and unavailable (double-lung; P = no significant difference). Linearized overall infection rates (events/100 patient-days) were 2.05 +/- 0.33 (heart-lung) and 2.34 +/- 0.34 (double-lung; P = NS) at 3 months. Thirty-day survival was 100% (heart-lung) and 96% (double-lung). There were 7 late deaths among heart-lung recipients (3 obliterative bronchiolitis, 2 infection, 0 graft coronary artery disease, 2 other) whereas 2 late deaths related to obliterative bronchiolitis occurred in double-lung recipients. Graft coronary artery disease (all stenoses < 50%) affected 15% of heart-lung survivors, whereas 3 double-lung recipients (12.5%) required either bronchial dilatation or stenting. CONCLUSION: Heart-lung and double-lung transplantation provide similar palliation for patients with end-stage suppurative lung disease. Therefore double-lung transplantation should be the preferred operation for most patients with end-stage suppurative lung disease.

Adult↗
PubMed1999

Heart-lung transplantation for primary pulmonary hypertension.

BACKGROUND: The operation of choice for primary pulmonary hypertension remains controversial, as heart-lung transplantation, single-lung transplantation, and double-lung transplantation have all been advocated. METHODS: We reviewed our institution's experience with heart-lung transplantation for primary pulmonary hypertension. RESULTS: Thirty-nine patients had heart-lung transplantation for primary pulmonary hypertension. Operative mortality rate was 18%, and actuarial survival was 72% at 1 year, 67% at 2 years, and 42% at 5 years. Freedom from obliterative bronchiolitis was 91% at 1 year, 83% at 2 years, and 70% at 5 years. Freedom from obliterative bronchiolitis-related death was 100% at 1 year, 90% at 2 years, and 87% at 5 years. Freedom from accelerated graft coronary disease was 92% at 5 years. The most frequent causes of death were infection, obliterative bronchiolitis, and accelerated graft coronary disease. CONCLUSIONS: Heart-lung transplantation results in survival comparable to that reported for single or double lung transplantation. Obliterative bronchiolitis is a significant cause of late death but seems to occur less frequently with heart-lung transplantation than with lung transplantation alone. Accelerated coronary graft disease is rare in the first 5 years after transplantation.

Adolescent↗
PubMed1999

Thirty years of cardiac transplantation at Stanford university.

BACKGROUND: The experience with 30 years of cardiac transplantation at Stanford University Medical Center was reviewed. A total of 954 transplants were performed in 885 patients. Patients were divided into 3 groups based on immunosuppression received: group I, no cyclosporine (INN: ciclosporin) (n = 201) (January 1968-November 1980); group II, cyclosporine (n = 248) (December 1980-June 1987); and group III, cyclosporine + OKT3 (n = 436) (July 1987-March 1998). RESULTS: The 1-, 5-, and 10-year actuarial survivals were 68%, 41%, and 24% (group I); 80%, 57%, and 37% (group II); and 85%, 68%, and 46% (group III) (I vs II, P <.01; I vs III, P <.005; and II vs III, P <.005). The 1-, 5-, and 10-year actuarial death rates from rejection were 8%, 12%, and 14% (group I); 5%, 7%, and 7% (group II); and 2%, 5%, and 5% (group III) (I vs II, P = not significant; I vs III, P <.005; and II vs III, P <.005). The 1-, 5-, and 10-year actuarial death rates from infection were 25%, 43%, and 50% (group I); 8%, 17%, and 29% (group II); and 6%, 11%, and 16% (group III) (I vs II, P <.005; I vs III, P <.005; and II vs III, P <.05). The 1-, 5-, and 10-year actuarial death rates from graft coronary artery disease were 0%, 5%, and 13% (group I); 0%, 12%, and 19% (group II); and 1%, 6%, and 9% (group III) (I vs II, P <.01; I vs III, P <.005; and II vs III, P = not significant). There have been 69 retransplants in 67 patients with 1-, 5-, and 10-year actuarial survivals of 49%, 27%, and 15%, respectively. CONCLUSIONS: The evolution of 3 decades of experience with cardiac transplantation has resulted in improved overall survival. The incidence of rejection and of death from infection and graft coronary artery disease have decreased over time, primarily as a result of improvements in immunosuppression and in the prevention and treatment of infection. Continued advances in perioperative management and the development of more specific, less toxic immunosuppressive agents could further refine this initial experience and improve the survival and quality of life of patients after cardiac transplantation.

Academic Medical Centers↗
PubMed1999

Exercise-induced hyperkalemia and concentration of Na,K-pumps in skeletal muscle in mitral stenosis: effect of balloon mitral valvotomy.

BACKGROUND AND AIMS OF THE STUDY: The study aim was to examine the effects of balloon mitral valvotomy (BMV) on exercise-induced hyperkalemia, and on changes in the concentration of Na,K-pumps in skeletal muscle, as an exaggerated exercise-induced rise in potassium concentration ([K+]) may contribute to exertional fatigue and breathlessness. METHODS: Eight subjects were evaluated with mitral stenosis (mean age 34 +/- 5.2 years) before, and at two weeks and four months after BMV. Subjects underwent incremental exercise to exhaustion for exercise-induced rise in [K+] and vastus lateralis biopsy for concentration of Na,K-pumps. RESULTS: Mean (+/- SE) valve area increased from 0.89 +/- 0.03 cm2 before to 1.75 +/- 0.05 cm2 after BMV. There was a progressive increase in VO2,max (15.3 +/- 1.6, 17.2 +/- 1.4 and 19.9 +/- 1.9 l/kg/min) at baseline, early after and later after BMV, respectively (p < 0.01). The rise in [K+] with absolute workload fell progressively at early and late follow up post-BMV (p < 0.05), but was unchanged when plotted against percentage of VO2,max to match for relative workload. The concentration of Na,K-pumps was similar to baseline at early follow up (233 +/- 10 versus 228 +/- 15 pmol/g wet weight), but was significantly increased at late follow up after four months (265 +/- 17 pmol/g; p < 0.05). When the relationship between the concentration of Na,K-pumps and the exercise-induced rise in [K+] was studied, a negative correlation was found. However, correlation analysis for the effects of changes in Na,K-pumps on changes in exercise hyperkalemia after BMV was not significant. CONCLUSIONS: The progressive reduction in exercise-induced rise in [K+] after BMV may contribute to the progressive improvement in exercise performance. The increased concentration of Na,K-pumps in skeletal muscle may assist in this improvement, and emphasizes the importance of peripheral adaptations in clinical improvement after BMV.

Adult↗
PubMed1998

Leg blood flow and increased potassium release during exercise in chronic heart failure: effect of physical training.

BACKGROUND: Exercise-induced hyperkalemia, which may contribute to exercise hyperpnea and exertional fatigue, is increased in patients with chronic heart failure (CHF). This study examined whether differences in leg blood flow during exercise could be responsible for alterations in the level of hyperkalaemia, as well as the effect of physical training. METHODS AND RESULTS: We studied 10 subjects with CHF (ejection fraction 23 +/- 3.9%; mean +/- SD) and 10 subjects with normal left ventricular function (NLVF) who had undergone previous coronary bypass graft surgery (ejection fraction 64 +/- 8.0%; mean +/- SD). Subjects performed incremental cycle exercise to exhaustion before and after physical training. The rises in femoral venous potassium concentration ([K+]), heart rate, lactate, and ventilation (VI) with exercise were all greater in the subjects with CHF than in those with NLVF (P < .05). There was no difference between the groups in leg blood flow during submaximal exercise but peak leg flow was greater in the group with NLVF (P < .01). Physical training was well tolerated and both groups increased their peak VO2 (8 +/- 3.2% CHF (P < .05); 11 +/- 2.7% NLVF (P < .01); mean +/- SE). Training resulted in a reduced rise in femoral venous [K+] and VI (P < .05), but did not affect leg blood flow during submaximal exercise in either group. CONCLUSIONS: The rise in the femoral venous [K+] with exercise is increased in patients with CHF and can be reduced by physical training. These changes are not a consequence of different leg blood flows, either between groups or with training. The study also suggests that femoral venous [K+] is not a powerful regulator of leg blood flow during exercise.

Aged↗
PubMed1997

Cost implications of mitral valve replacement versus repair in mitral regurgitation.

BACKGROUND: Mitral valve repair and replacement (MVR) with preservation of the tendinous chordae [MVR(p)], may have better results than MVR with valve excision [MVR(e)]. It is not known whether the type of surgery affects in-hospital stay and cost. METHODS AND RESULTS: We reviewed all patients who had mitral valve surgery for regurgitation over 5 years from January 1991. Patients were considered in three groups; MVR(e), MVR(p), and Repair. Cost was calculated using operating room, intensive care unit, and ward expenses, not hospital charges. There were a total of 253 patients; 84 MVR(e), 42 MVR(p), and 127 Repair. Mean ages and preoperative New York Heart Association (NYHA) classes were similar in the three groups. There were more male patients in the Repair (62%) and MVR(p) (67%) groups than in the MVR(e) (44%) group (P<.05), and more patients with degenerative etiology in the Repair group (P<.01). A majority of MVR(e) were in atrial fibrillation (63%), while 59% of Repair were in sinus rhythm (P<.01). Of 9 patients who died in the hospital; four had MVR(e), 3 had MVR(p), and 2 had Repair. In univariate analyses, in-hospital stay increased with patient age >70 years (P<.01), preoperative atrial fibrillation (P<.05), and NYHA class III or IV (P<.01). The median and interquartile ranges for postoperative stay was 10 (8 to 13) days for MVR(e), 8 (7 to 11) days for MVR(p), and 8 (7 to 10) days for Repair (P<.01 versus MVR(e); multivariate analysis adjusting for age, rhythm, and NYHA class). Cost per patient was US $14469 for MVR(e), $13151 for MVR(p), and $11606 for Repair. CONCLUSIONS: Repair and MVR(p) may predict shorter in-hospital stay and reduced cost, although there are important differences in the group of patients who have MVR(e).

Aged↗
PubMed1997

Effect of heart failure and physical training on the acute ventilatory response to hypoxia at rest and during exercise.

We studied the acute ventilatory response to hypoxia (AHVR) in 10 patients with chronic heart failure (CHF) and in 10 subjects with normal left ventricular function (NLVF) before and after 8 weeks of home-based physical training. Subjects were studied at rest and during constant cycle exercise at a work rate equivalent to 40% of their maximum oxygen consumption. The AHVR was not significantly different between the patients with CHF and those with NLVF either at rest (1.32 +/- 0.19 vs. 1.63 +/- 0.20 litres/min/% arterial desaturation; mean +/- SE) or during constant light exercise (2.37 +/- 0.48 vs. 2.86 +/- 0.55 litres/min/% arterial desaturation). Both groups showed evidence of improved physical fitness after training with increases in maximum oxygen consumption of 11 +/- 2.7% (p < 0.01) for the group with NLVF and of 8 +/- 3.2% (p < 0.05) for the group with CHF. Values for the AHVR in the trained state were not significantly different between the patients with CHF and those with NLVF either at rest (1.23 +/- 0.24 vs. 1.63 +/- 0.22 litres/min/% arterial desaturation) or during constant light exercise (2.52 +/- 0.69 vs. 2.24 +/- 0.37 litres/min/% arterial desaturation). Moreover, these responses did not differ from those in the untrained state (see above). The AHVR increased during exercise compared with rest in both groups (p < 0.05). The AHVR is not substantially altered in patients with CHF compared to subjects with NLVF. Physical training may reduce ventilation during exercise, but it has relatively little or no effect on the AHVR. However, exercise increases the AHVR in patients with CHF, as it does in normals.

Carbon Dioxide↗
PubMed1995

Exercise capacity and skeletal muscle structure and function before and after balloon mitral valvuloplasty.

This study evaluated the effects of balloon mitral valvuloplasty (BMV) on exercise capacity and skeletal muscle structure and function in 10 subjects with mitral stenosis (mean age +/- SD 33 +/- 5.5). Measurements were obtained before, and 2 weeks and 4 months after BMV to provide baseline data, to examine the effects of improved hemodynamics, and to examine the effects of resumption of normal physical activity, respectively. Valvuloplasty caused an increase in mitral valve area (0.89 +/- 0.04 to 1.75 +/- 0.07 cm2; mean +/- SE), and an increase in resting cardiac output (3.8 +/- 0.18 to 4.6 +/- 0.19 L/min, p < 0.05). At early follow-up after 2 weeks, subjects did more work (31% increase, p < 0.01) and had greater maximal oxygen consumption (11% increase, p < 0.01). However, measurements reflecting skeletal muscle histology, biochemistry, and function were unaltered at this stage. Four months after BMV, subjects had a further increase in exercise capacity compared with both baseline (58% increase, p < 0.01) and early follow-up (20% increase, p < 0.05). There were associated late increases compared with baseline in quadriceps cross-sectional area (66 +/- 5.8 vs 61 +/- 5.5 cm2, p < 0.05) and torque production (125 +/- 14 vs 118 +/- 16 Nm, p < 0.05). The percentage of slow twitch type I fibers increased compared with baseline (41 +/- 2.0% vs 33 +/- 3.1%, p < 0.05), as did the size of type II fibers (5.9 +/- 0.49 vs 4.9 +/- 0.57 microns2 x 10(3), p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effect of raised potassium on ventilation in euoxia, hypoxia and hyperoxia at rest and during light exercise in man.

The purpose of this study was to determine whether changes in arterial plasma potassium concentration [K+]a affect expired ventilation (VE) in euoxia, hypoxia and hyperoxia during rest and light exercise in humans. Three periods of ventilatory measurements were undertaken in eight healthy subjects at rest and in seven other subjects during cycle ergometry (70 W). The first period of measurement was before the ingestion of 64 mmol of potassium chloride (KCl), the second 20 min after ingestion of KCl when [K+]a levels were elevated, and the third 3 h after the ingestion of KCl when [K+]a had returned substantially to normal. During each period, end-tidal PO2 was cycled between euoxia, hypoxia and hyperoxia, whilst the end-tidal PCO2 was maintained constant. The acute ventilatory response to hypoxia (AHVR) was calculated as the difference in VE during hypoxia and hyperoxia within each period of measurement. Oral KCl produced a 1.3 +/- 0.2 mM (mean +/- S.E.M.) increase in [K+]a at rest and a 0.8 +/- 0.2 mM increase during exercise. There was no significant difference in ventilation during euoxia between the three periods of measurement at rest or during exercise. There was a significant increase in AHVR with the rise in [K+]a of 21 min-1 mM-1 at rest (arterial PO2 during hypoxia ca 57 Torr) and 10 l min-1 mM-1 during exercise (arterial PO2 during hypoxia ca 52 Torr). There was a significant difference in the absolute increase in AHVR with [K+]a between rest and exercise, but this difference was not significant if the increase in AHVR with [K+]a was expressed as a percentage of the initial AHVR. We conclude that changes in [K+]a of the order of 1 mM have little effect on euoxic ventilation at rest or during light exercise in humans. We also conclude that [K+]a changes of this order increase AHVR at rest and during light exercise and that increases in [K+]a contribute to the increase in AHVR with exercise in humans.

Adult↗
PubMed1994

Effect of hypoxia on arterial potassium concentration at rest and during exercise in man.

Hypoxia has been reported to increase arterial potassium concentration ([K+]a) in anaesthetized cats (Paterson, Estavillo & Nye, 1988). The purpose of this study was to determine whether this phenomenon occurs in humans. The effect of hypoxia on [K+]a was measured in ten male subjects, at rest and during light exercise, before and after 8 weeks of physical training. The [K+]a increased by 0.15 +/- 0.04 mM (mean +/- S.E.M.) at rest, when end-tidal PO2 (PET,O2) was lowered from 100 to 51 +/- 1.6 Torr, and by 0.10 +/- 0.02 mM during exercise, when PET,O2 was lowered from 100 to 66 +/- 6.2 Torr. Physical training did not alter the rise in [K+]a significantly. The magnitude of this effect is small in comparison with that of exercise-induced hyperkalaemia, and is unlikely to be of great physiological significance at moderate levels of hypoxia.

Arteries↗
PubMed1994

Effect of physical training on exercise-induced hyperkalemia in chronic heart failure. Relation with ventilation and catecholamines.

BACKGROUND: The exercise-induced rise in arterial potassium concentration ([K+]a) may contribute to exercise hyperpnea and could play a role in exertional fatigue. This study was designed to determine whether the exercise-induced rise in [K+]a is altered in patients with chronic heart failure (CHF) and whether physical training affects K+ homeostasis. METHODS AND RESULTS: We evaluated 10 subjects with CHF (ejection fraction, 23 +/- 3.9%) and 10 subjects with normal left ventricular function (NLVF) who had undergone previous coronary artery graft surgery (ejection fraction, 63 +/- 8.6%). Subjects performed an incremental cycle ergometer exercise test before and after a physical training or detraining program. Changes in [K+]a and ventilation (VE) during exercise were closely related in both groups. Subjects with CHF did less absolute work and had reduced maximal oxygen consumption (VO2max) compared with subjects with NLVF (P < .01). Exercise-induced rises in [K+]a, VE, norepinephrine, lactate, and heart rate were greater at matched absolute work rates in subjects with CHF than in subjects with NLVF (P < .01). However, when the rise in [K+]a was plotted against percentage of VO2max to match for relative submaximal effort, there were no differences between the two groups. Physical training resulted in reduced exercise-induced hyperkalemia at matched submaximal work rates in both groups (P < .01) despite no associated change in the concentration of arterial catecholamines. At maximal exercise when trained, peak increases in [K+]a were unaltered, but peak concentrations of catecholamines were raised (P < .05). The decrease in VE at submaximal work rates after training was not significant with this incremental exercise protocol, but both groups had an increased peak VE when trained (P < .01). CONCLUSIONS: Exercise-induced rises in [K+]a, catecholamines, and VE are greater at submaximal work rates in subjects with CHF than in subjects with NLVF. Physical training reduces the exercise-induced rise in [K+]a but does not significantly decrease VE during submaximal exercise with this incremental cycle ergometry protocol. The reduction in exercise-induced hyperkalemia after training is not the result of altered concentrations of arterial catecholamines. The pathophysiological significance of the increased exercise-induced hyperkalemia in CHF and the mechanisms of improved K+ homeostasis with training have yet to be established.

Epinephrine↗
PubMed1992

The importance of assessing time-course behaviour of abnormal ST/T changes after exercise.

Routine stress electrocardiography has been criticised for yielding too many so-called 'false-positive' results because ST/T changes that develop during and after exercise are prevalent. Recent studies in our institution indicate, however, that the time-course behaviour patterns of these ST/T configurational 'abnormalities' after exercise are different from those reflecting myocardial ischaemia due to epicardial coronary artery disease (CAD). Time-course analysis increases the predictive value of exercise testing and has dramatically decreased the number of asymptomatic subjects or symptomatic patients at low risk of having CAD being subjected to coronary arteriography in our institution. Our method of assessing post-exercise time course patterns of abnormal ST/T are described in detail. Ischaemic ST/T abnormalities have late onset, early offset or early onset, late offset whereas those ST/T changes associated with normal epicardial coronary arteries have late onset, late offset or early onset, early offset post-exercise time course patterns.

Coronary Disease↗
PubMed1991

Observer accuracy and confirmation of the important role of abnormal ST/T time course behavior in the evaluation of stress electrocardiograms.

Routine exercise electrocardiography has been criticized for yielding too many so-called "false-positive" results. Recent studies in our institution indicate that evaluation of the time course behavior of ST segment and T wave (ST/T) changes after cessation of exercise differentiates ischemic from non-ischemic ("false-positive") stress electrocardiograms (SEs). Our method of assessing time course behavior is clarified. The principal aim of this study was to determine the accuracy of experienced observers in making this differentiation. Records of consecutive patients undergoing coronary arteriography over a 2 year period were reviewed and 30 with SEs judged positive for ischemia by the widely accepted ST/T configurational criteria alone were selected at random for the investigation. Sixteen subjects had normal coronary angiograms and had therefore previously been regarded as having false-positive SEs. Fourteen patients had at least one significantly (> 70%) stenosed coronary artery which was our yardstick for ruling that true myocardial ischemia, due to epicardial coronary artery disease (CAD), was present. Five observers, familiar with post-exercise ST/T time course patterns, independently and "blindly" analyzed all 30 configurationally abnormal SEs. Observers were informed only of the patient's age and sex; they were thus unaware of symptoms, exercise variables, coronary anatomy and the number of patients in the 2 groups. The observer consensus for ischemia of SEs using time course analysis was: total test accuracy 87%, sensitivity 79%, specificity 94%, positive predictive value 92% and negative predictive value 83%. Because all 30 patients had ST/T abnormalities, results of the sample for ischemia based on configurational criteria alone were sensitivity 100%, specificity 0% and positive predictive value 47%. We concluded that time course analysis plays a crucial role in evaluating SEs and that exercise electrocardiography remains a safe, cost-effective and reliable method of screening many asymptomatic, as well as symptomatic, subjects for CAD.

Coronary Angiography↗
PubMed1991

Post-exercise time-course analysis of ST segment and T wave changes: an important contribution to the role of stress electrocardiography in aircrew.

Flight surgeons recognize that ongoing vigilance is necessary to detect coronary artery disease (CAD) in aircrew. Regular physical examinations with only a resting electrocardiogram, albeit having a very low predictive value for detection of CAD in asymptomatic subjects, are now widely practised. Routine stress electrocardiography has been criticized for yielding too many so-called "false positive" results because ST/T changes that develop during and after exercise are prevalent. Recent studies in our institution indicate, however, that the time-course behavior patterns of these ST/T configurational "abnormalities" after exercise are different from those reflecting myocardial ischemia due to epicardial CAD. Time-course analysis increases the predictive value of exercise testing and has dramatically decreased the number of asymptomatic aircrew being subjected to coronary arteriography in our institution. Routine exercise electrocardiography provides a reliable, cost-effective means of detecting aircrew with CAD and a baseline for comparison at subsequent examination, and we strongly recommend that it be universally reinstated.

Adult↗