Terrestrial apnoeas and the development of cardiac control in Australian fur seal (Arctocephalus pusillus doriferus) pups

The development of cardiac control in association with terrestrial respiration patterns was examined throughout the period of maternal dependence in Australian fur seal pups. Resting eupnoic heart rate and respiration rate were significantly correlated (r² = 0.49) and both decreased with age (P < 0.05 in both cases). From an early age (1 month), pups displayed terrestrial apnoeas (18.1 ± 0.5 s) accompanied by substantial bradycardia (127 beats min^-1, a 13% decrease from eupnoic HR). Terrestrial apnoea duration increased significantly with age reaching a mean of 41 s just prior to weaning, slightly lower than the mean dive duration (52 s) previously recorded for pups of the same age. Correspondingly, mean apnoic heart rate decreased with age to 74 beats min^-1 just prior to weaning, representing a 25% decrease on eupnoic heart rate. Importantly, concomitant with the decrease in mean apnoic heart rate with age, an increase in the control
of bradycardia was evident with the variability in instantaneous apnoic heart decreasing such that older pups were able to maintain a low steady heart rate for the duration of the apnoea. The changes seen in these parameters are similar to those reported during postnatal development in elephant seals (Mirounga spp.) and harbour seals (Phoca vitulina), and are considered indicative of the development of cardiac control. These findings suggest a common strategy for the development of bradycardia control in both otariid and phocid seals.

Antecedents to postoperative pulmonary dysfunction in adults after cardiac surgery

The previously unexplored trajectory of postoperative pulmonary dysfunction was mapped in adults having cardiac surgery. Factors including hypoxaemia, positive fluid balance, severe pain and impaired functional status were associated with the development of pulmonary dysfunction and pneumonia. These antecedents are amenable to treatment in the form of prompt preventative nursing intervention that has a fundamental influence on patient outcome.

Nutrition care for adult cardiac patients : Australian general practitioners' perceptions of their role

Background. Australia has implemented systematic managed care for patients with chronic disease. Little is known about how GPs perceive their nutrition care role in this system.
Objective. To examine GPs’ perceptions of their roles in the nutrition care of cardiac patients and to identify factors that influence their role.
Methods. Multi-methods research design. Semi-structured interviews were conducted with a sample (n = 30) GPs Victoria, Australia. The resulting narratives were used to develop a quantitative questionnaire to survey a random sample of GPs. Principal components analysis was conducted to reduce the role items to a small number of underlying dimensions. The association between roles and demographic variables were examined using stepwise multiple regressions.
Results. In all, 248 GPs (30% response) participated. Three main roles were established: Influencing, Coordinating and Nutrition Educator role. Together, the roles explained 54% of the total variance. Demographic variables were not associated with these roles. The majority (mean = 88%) endorsed the items which loaded on to the Influencing and Coordinating (mean = 49%) roles. Short consultation time, use of prescribed medications and perception of patient attendance at cardiac rehabilitation reduced the priority for nutrition education.
Conclusions. This study highlights the importance of developing more effective team care arrangements for patients with chronic disease and working with the medical education colleges to develop education resources for doctors that include an explanation of the non-pharmaceutical as well as the pharmaceutical treatment for each chronic disease condition.

Contribution of Australian cardiologists, general practitioners and dietitians to adult cardiac patients’ dietary behavioural change

Aim:  To investigate the use of behavioural change techniques by cardiologists, general practitioners and dietitians in adult cardiac patients within 12 months of their cardiac event.
Method:  Quantitative cross-sectional surveys. Frequency analyses were conducted on the respondents' answers to questionnaire items. Chi-squared test of independence compared responses of the three professional groups on the questionnaire items. Analyses of variance were conducted to explore the impact of the independent variables: age, sex and time worked on the behavioural change techniques used by the respondents.
Results:  The respondents included 248 general practitioners (30% response), 189 cardiologists (47% response) and 180 dietitians (60% response). General practitioners and cardiologists acted mainly as advocates for dietary change in the dietary management process. Dietitians provided nutrition knowledge and a range of techniques to assist dietary behavioural change. Cardiologists and dietitians shared little nutrition information with general practitioners (cardiologists with general practitioners = 8%, dietitians with general practitioners = 49%).
Conclusion:  The present study shows that cardiac patients may have insufficient access to knowledge of nutrition and techniques to assist them with dietary behavioural change.

Recovering from an acute cardiac event – the relationship between depression and life satisfaction

Aims. This study sought to measure the rates and trajectory of depression over six months following admission for an acute cardiac event and describe the relationship between depression and life satisfaction.
Background. Co-morbid depression has an impact on cardiac mortality and is associated with the significant impairment of quality of life and well-being, impairments in psychosocial function, decreased medication adherence and increased morbidity.
Design. This was a descriptive, correlational study.
Method. The study was undertaken at a large public hospital in Melbourne. Participants were asked to complete a survey containing the cardiac depression scale (CDS) and the Personal Well-being Index.
Results. This study mapped the course of depression over six months of a cohort of patients admitted for an acute cardiac event. Significant levels of depressive symptoms were found, at a level consistent with the literature. A significant correlation between depressive symptoms as measured by the CDS and the Personal Well-being Index was found.
Conclusions. Depression remains a significant problem following admission for an acute coronary event. The Personal Wellbeing Index may be a simple, effective and non-confrontational initial screening tool for those at risk of depressive symptoms in this population. Relevance to clinical practice. Despite the known impact of depression on coronary heart disease (CHD), there is limited research describing its trajectory. This study makes a compelling case for the systematic screening for depression in patients with CHD and the importance of the nursing role in identifying at risk individuals.

Cardiac structure and function in young endurance athletes and nonathletes

The purpose of this study was to examine, in male adolescents, the effects of long-term endurance training on cardiac structure and function, by adopting a cross-sectional comparison with a nonathletic control group. A total of 13 endurance-trained (EX) and seven untrained (CON) male adolescents (mean ± SE, age = 15.3 ± 0.3 and 15.2 ± 0.28 yrs, respectively) underwent echocardiography at rest to determine left ventricular enddiastolic dimension (LVD_d), left ventricular end-systolic dimension (LVD_s), left ventricular posterior wall thickness (LVPW), stroke volume (SV), and cardiac output (CO). On separate days, incremental exercise tests were conducted on a cycle ergometer to measure peak oxygen uptake (VO_2max) and anaerobic power. VO_2max was greater in the endurance group (54.4 ± 1.8 mL min^–1 kg^–1) than in the control group (45.8 ± 1.6 mL min^–1 kg^–1; p < 0.05). Mean exercise time was longer in EX (12.9 ± 0.7 min) than CON (10.4 ± 0.8 min; p < 0.05). No significant differences were noted between the two groups in resting heart rate, maximal heart rate, LVD_d, LVD_s, LVPW, SV, SV indexed, CO, and CO indexed, or in the anaerobic strength. These data provide evidence that endurance-trained adolescent males develop superior exercise performance before the cardiac remodeling that is evident in trained adult athletes.

Voluntary exercise does not affect stress-induced tachycardia, but improves resistance to cardiac arrhythmias in rats

1. It is currently unknown whether long-term voluntary exercise has enduring cardioprotective effects in animal models.

2. The present study was conducted in three groups of rats: (i) sedentary controls (n = 6); (ii) 24 h runners (n = 8; unlimited access to running wheels); and (iii) 2 h runners (n = 8; access to running wheels limited to 2 h daily). After termination of the 6 week exercise protocol, all rats were implanted with the telemetric electrocardiogram transmitters and were studied 1 week later.

3. Resting heart rate (HR) values in the control rats, 24 h runners and 2 h runners were 372 ± 7, 361 ± 9 and 298 ± 5 b.p.m., respectively (P < 0.05 for 2 h runners vs controls). The high-frequency spectral power in the control rats, 24 h runners and 2 h runners was 3.9 ± 0.2, 4.3 ± 0.3 and 5.3 ± 0.3 s2, respectively (P < 0.05 for 2 h runners vs controls), whereas intrinsic HR was 383 ± 3, 377 ± 2 and 346 ± 3 b.p.m., respectively (P < 0.001 for 2 h runners vs controls). Restraint stress provoked tachycardia of similar magnitude in all groups.

4. After completion of telemetric studies, haemodynamic indices and susceptibility to cardiac arrhythmias were assessed in anaesthetized animals, there were no major between-group differences in HR, arterial pressure, contractility indices or sensitivity to β-adrenoceptor stimulation (dobutamine) or blockade (atenolol). The effective refractory period in the control rats, 24 h runners and 2 h runners was 49 ± 2, 55 ± 2 and 60 ± 4 ms, respectively (P = 0.054 for 2 h runners vs controls). A significantly higher dose of aconitine was required to provoke ventricular arrhythmias in the 24 h and 2 h running groups compared with controls (489 ± 76, 505 ± 88 and 173 ± 33 μg, respectively; P < 0.05).

5. We conclude that, in rats, long-term voluntary exercise has enduring cardioprotective effects mediated at the level of both the central nervous system and the heart.