P909 Diagnostic evaluation of rheumatic heart disease in aborigonal population

Background

Among Indigenous Australians, rates of Acute Rheumatic Fever (ARF) continue to be among the highest in the world. Diagnosis remains a clinical decision based on identification of major and minor manifestations of the illness. Treatment involves lengthy prophylaxis and should continue for a minimum of 10 years.

ARF can cause permanent damage to the heart known as rheumatic heart disease (RHD).

We therefore utilised echocardiography as a diagnostic tool incorporating Tissue Quantification Backscatter expressed in decibels (dB) and global LV work efficiency estimated from left ventricle (LV) pressure-strain loops to identify rheumatic changes of the Mitral Valve and help improve early diagnosis of RHD.

Method

Data from patients with suspected RHD (n = 14), and age matched controls (n = 10) underwent Mitral Valve Backscatter Analysis (MVBS). MVBS was expressed as a ratio % (MVBS ratio %) by dividing the average MVBS and the average blood pool value expressed in decibels (dB). Furthermore LV function was utilised via 2D longitudinal strain and indices of myocardial work were derived.

Result

MVBS ratio % was significantly higher in the control group as compared to the RHD group (p = 0.001) (fig1). Of the RHD group echocardiography parameters showed there were no significant mitral valve stenosis or regurgitation. Correlates of LV function included: Global work Index (GWI), Global longitudinal Strain (GLS) and Global work efficiency (GWE). Of the above correlates the control group showed Backscatter vs GLS (r= -0.89, p = 0.001), the RHD group: Backscatter vs GLS (r = 0.52. p = 0.12). Within the RHD group the ratio vs GWE (r= 0.57, p = 0.09) these results showed a trend to significance.

Conclusions

Currently diagnosis of RHD remains a clinical decision based on the identification of major and minor manifestations. In addition treatment involves prophylaxis injections for a minimum of ten years. Of this group there were no significant echocardiography changes, rather clinical manifestation to derive RHD.

This study shows that calibrated MVBS ratio % and determinants of myocardial work may be a promising quantitative tool to detect early manifestation of RHD potentially aiding an early treatment plan and thus reducing the clinical burden of monthly penicillin injections for a ten year period.

Abstract P909 Figure. RHD and Myocardial correlates

Unperceived treatment gaps in acute coronary syndromes

BACKGROUND

Despite a strong evidence-base for several therapies recommended in the management of acute coronary syndromes (ACS), many patients do not receive these therapies. The barriers preventing translation of evidence into practice are incompletely understood. The aim of this study was to survey clinicians regarding barriers to implementing recommendations of recently published national clinical guidelines and to determine the extent to which these impact clinical practice.

METHODS

A survey of clinicians at hospitals included in Australian Collaborative Acute Coronary Syndromes Prospective Audit (ACACIA, n = 3402, PML0051) was conducted, measuring self-stated knowledge, beliefs and guideline-concordant behaviours in relation to their care of ACS patients. Correlations between individual respondents' self-estimated rates and clinician's institutional rates of guideline-concordant behaviours were performed.

RESULTS

Most respondents (n = 50/86, 58%) were aware of current guidelines and their scope, achieving 7/10 (Interquartile Range (IQR) = 2) median score on knowledge questions. Belief in benefits and agreement with guideline-recommended therapy was high. However, none of these factors correlated with increased use of guideline therapies. Apart from clopidogrel (r(s) = 0.28, p < 0.01) and early interventional therapy for high-risk non-ST elevation myocardial infarction (r(s) = 0.31, p < 0.01), there were no significant correlations between individual clinicians' self-estimated rates of guideline-concordant practice and rates recorded in ACACIA data for their respective institution.

CONCLUSION

Beliefs about practice do not match actual practice. False beliefs regarding levels of evidence-based practice may contribute to inadequate implementation of evidence-based guidelines. Strategies such as continuous real-time audit and feedback of information for the delivery of care may help clinicians understand their levels of practice better and improve care.

Temporal trends in major angioplasty complications: technical issues and the case for on-site coronary surgery

The need for on-site cardiac surgery has been a component of guidelines for the practice of elective and emergency percutaneous coronary intervention (PCI). However, proportions of cases requiring emergency coronary artery bypass grafting (CABG) post-PCI have fallen. This audit of complications of PCI confirms the very low incidence of need for emergency CABG, despite increasingly complex PCI caseload. Although the availability of stents/antiplatelet pharmacotherapy probably has contributed to improved PCI outcomes, the avoidance of emergency CABG is not contingent on either extensive use of glycoprotein IIb/IIIa inhibitors or strategies of universal stenting.

Using the ability to perform CPR as a standard of fitness: a consideration of the influence of aging on the physiological responses of a select group of first aiders performing cardiopulmonary resuscitation

OBJECTIVE

Previous research has suggested that the physical demands of performing cardiopulmonary resuscitation (CPR) are relatively low. However, the subjects studied have generally been of a young age. The aim of this study was to test the hypothesis, in null form, that the physiological responses to the performance of single operator CPR for 10 min are independent of age. Confirmation of the hypothesis would allow the use of a period of time performing CPR as a socially non-discriminatory means of testing ability across a wide spectrum of age.

DESIGN

33 St. John Operations Branch members (a sample of convenience), aged between 18 and 65 years, were examined whilst performing 10 min of single operator CPR on a manikin at St. John Ambulance Headquarters, Adelaide, South Australia. Heart rate and cardiac rhythm were monitored continuously. Blood pressure was recorded at baseline and the end of the 3rd, 6th and 9th min of CPR. Subjects also rated their perceived level of activity using the 15-point Borg rating scale every 3 min and at the end of the test.

RESULTS

The calculated rate-pressure product did not vary significantly with age, either at rest or in response to performing CPR. The rate-pressure product increased significantly (P < 0.05) whilst performing CPR. There was no effect of age on the perceived level of exertion, which also increased significantly during CPR as compared with rest.

CONCLUSION

There was no significant effect of age on the physiological responses to the performance of 10 min of single operator CPR in this select group.

The positive inotropic effects of milrinone but not of digoxin are attenuated at short cycle lengths

The effects of inotropically active agents on the left ventricular force-interval relation are a potential determinant of their clinical utility and safety. However, little information is available concerning the effects of noncatecholamine positive inotropic agents on this relation. Therefore this study compared the short-term effects of digoxin and milrinone on resting hemodynamics, frequency potentiation (FP), and mechanical restitution (MR) in patients undergoing nonemergency cardiac catheterization. Both digoxin and milrinone produced similar increases in LV + dP/dt at rest (12.2 +/- 1.3%, p < 0.000001 and 11.4 +/- 3.2%, p < 0.01, respectively). The positive inotropic effects of digoxin were marginally attenuated during FP (by 8.5 +/- 4.2% and 4.6 +/- 2.9% at 10 and 60 s, respectively, both p = NS compared with baseline). Similarly, on MRC analysis, the parameter c (a measure of sensitivity of contractile performance to reductions in cycle length) increased by 3.6 +/- 3.7% (p = NS). Whereas the positive inotropic effects of milrinone were not significantly attenuated during FP, they were abolished and possibly reversed at short cycle lengths on MR curve construction (6.8 +/- 5.9% negative inotropic effect at 60% of resting cycle length; p = NS; p < 0.05 vs. resting cycle length). In conclusion, in patients with well-preserved left ventricular systolic function, the positive inotropic effects of milrinone but not of digoxin are markedly dependent on heart rate. These properties may influence both relative safety and efficacy of both agents.

Nitrate therapy is an alternative to furosemide/morphine therapy in the management of acute cardiogenic pulmonary edema

BACKGROUND

Nitrates are superior to furosemide in the management of acute pulmonary edema associated with myocardial infarction; however, their role in the absence of infarction is unclear.

METHODS AND RESULTS

A randomized comparison was undertaken of the relative effectiveness of primary therapy with either intravenous morphine/furosemide (men/women; n = 32) or nitroglycerin/N-acetylcysteine (NTG/NAC; n = 37) in consecutive patients with acute pulmonary edema. The primary end point was change in PaO2/FIO2 over the first 60 minutes of therapy. Secondary end points were needed for mechanical respiratory assistance (ie, continuous positive airway pressure via mask or intubation and ventilation) and changes in other gas exchange parameters. Both treatment groups showed improvement in oxygenation after 60 minutes of therapy; however, this reached statistical significance only with NTG/NAC therapy. There was no significant difference between groups in the assessed parameters (95% CI for differences in Pao2/FIO2: furosemide/morphine -12 to 23 and NTG/NAC 4 to 44), a finding also confirmed in 32 patients presenting with respiratory failure. Only 11% of the study group required mechanical ventilatory assistance (continuous positive airway pressure in 4 patients and intubation and ventilation in 3 patients).

CONCLUSIONS

NTG/NAC therapy is as effective as furosemide/morphine in the initial management of acute pulmonary edema, regardless of the presence or absence of respiratory failure. The necessity for mechanical ventilatory assistance is infrequent in these patients, regardless of the initial medical treatment regimen.