Pulmonary autograft versus homograft replacement of the aortic valve: A prospective randomized trial

AbstractBackground: Pulmonary autografts offer many theoretical advantages. However, the operation is complex, may interfere with right ventricular and pulmonary outflow function, and requires a longer operative time than does the homograft operation. The effects of these potential disadvantages are unknown. Methods: To clarify these issues we randomized 70 patients undergoing aortic valve replacement to an aortic homograft group (group A = 37 patients; 53%; 34 male, 3 female) or a pulmonary autograft group (group B = 33 patients; 47%; 28 male, 5 female). Ages varied from 12 to 65 years (mean 39 ± 15 years) for group A and from 3 to 54 years (mean 29 ± 15 years) for group B (p = not significant). Eleven patients in group A (30%) and eight in group B (24%) had previous aortic valve surgery. All patients were operated on by the same surgeon. The mean cardiopulmonary bypass time was 113 ± 29 minutes (range 66 to 175 minutes) for group A and 151 ± 31 minutes (range 115 to 226 minutes) for group B (p < 0.002). Mean aortic crossclamp time was 85 ± 19 minutes (range 45 to 140 minutes) for group A and 109 ± 20 minutes (range 74 to 164 minutes) for group B (p = 0.02). In 32 patients (86.5%) the aortic homograft was implanted as a root with coronary reimplantation. All pulmonary autografts were implanted as a root. Results: No early or late deaths had occurred in this series at a mean follow-up time of 16 months (range 3 to 21 months). Two patients (one in each group) required reexploration for bleeding. No statistically significant differences were observed between the two groups with regard to ventilatory support (group A, mean 10 ± 8.5 hours; group B, mean 29 ± 85 hours), total blood loss (group A, mean 471 ± 347 ml; group B, mean 543 ± 404 ml), intensive care unit stay (group A, mean 1.2 ± 0.6 days; group B, mean 2 ± 3.7 days), and hospital stay (group A, mean 9.5 = 3.2 days; group B, mean 12 ± 6 days). Postoperatively, all patients are in New York Heart Association class I (93%) or II (7%) (p = not significant). Ejection fraction for the two groups did not change significantly over the follow-up period. Left ventricular mass and diastolic diameter showed progressive regression, with no apparent difference between the two treatment groups to date. Echocardiographic evalu- ation of aortic valve function at 6 months showed good valve function in all patients with no evidence of aortic regurgitation in 80% of both groups. In group B the right ventricular outflow gradient was below 15 mm Hg over the follow-up period. Holter monitoring, available only in 44 patients (63%), showed most of the arrhythmias to be grade 0 to 1 of the modified Lown grading system. Conclusion: Although the pulmonary autograft requires a significantly longer operating time, this does not seem to affect early and medium-term outcome when compared with results obtained with aortic homografts. Continued patient evaluation is warranted, particularly with regard to evidence of valve degeneration and right ventricular function and arrhythmias in the long term. (J Thorac Cardiovasc Surg 1997;113:894-900

Cardiovascular autonomic control in patients undergoing left ventricular assist device (LVAD) support and pharmacologic therapy

Objectives The objective of the study is to determine cardiac autonomic control in patients undergoing assessment for and/or LVAD therapy. Methods Heart rate variability (HRV) was measured in 17 explanted LVAD, 17 implanted LVAD and 23 NYHA III-IV classified chronic heart failure (CHF) patients and ten healthy matched controls under three conditions: supine free breathing, standing and supine controlled breathing. Five measures of HRV were assessed: mean R-R interval (mR-R), high frequency (HF) and low frequency (LF) spectral power, LF in normalised units (LFnu), and LF to HF (LF:HF) ratio. Results Repeat measures ANOVA showed significant (p < 0.05) differences in HRV between all three conditions within groups. Lower values were observed in CHF for LF(in log natural units) compared with explanted patients (- 1.4 [95% CI - 2.6 to - 0.7], p = 0.04) and controls (- 2.1 [- 3.5 to - 0.7], p = 0.001) and for LF:HF compared with implanted patients under paced breathing conditions (z = - 2.7, p = 0.007) and controls in standing (z = - 2.9, p = 0.004) and paced breathing conditions (z = - 2.3, p = 0.02). However, no significant differences were seen between explanted, implanted and control groups under any condition. Conclusions Patients implanted with an LVAD and explanted from a LVAD following myocardial recovery demonstrate a more normal dynamic response to autonomic stimuli and have a lower HRV risk profile compared to CHF patients. © 2013 Elsevier Ireland Ltd

The effects of left ventricular assist devices on myocardial function and cardiac nervous system

Myocardial recovery in patients with non-ischaemic end-stage dilated cardiomyopathy can occur following left ventricular assist device (LVAD) and drug combination therapy. The effects of LVAD and drug combination therapy on the cardiac nervous system have not been adequately studied. It is well recognised that contractile reserve is decreased in heart failure patients who have an increased level of circulating norepinephrine secondary to failure of the myocardial norepinephrine transporter system. The aims of this study are to examine prospectively the outcome of using continuous-flow Heart Mate (HM) II LVAD and drug combination therapy on the frequency and durability of recovery, the clinical effects of left ventricular unloading on cardiac sympathetic nervous system, and the impact on norepinephrine transporter activity and neurohormonal levels. 23 non-ischaemic end-stage heart failure patients, confirmed histologically, were implanted with a HM II LVAD between February 2006 and March 2009. The combination therapy with anti-failure reverse remodelling medication was commenced once patients were off inotropes. The first objective was to determine a cut-off point where the contribution of the continuous-flow HM II LVAD was minimal thus allowing safe and reliable assessment of the underlying left ventricular function without causing left ventricular reloading. The impacts of LVAD and drug combination therapy on myocardial function and cardiac nervous system were assessed by studying: 1) contractile reserve using a 6–minute walk exercise test; 2) norepinephrine transporter using serial nuclear 123I-mtaiodobenzylguanidine (123I-MIBG) imaging; 3) the changes in catecholamine levels using liquid chromatography mass spectrometry. Immunohistochemistry was utilised to assess norepinephrine transporter fibre concentration from the left ventricular apex biopsies taken at implantation in an attempt to correlate with myocardial recovery. Experimental and clinical studies identified 6000 rpm as an efficient and a safe "low" speed to study the underlying myocardial function. Out of the 23 patients, 15 had recovered and had significant improvement in contractile reserve (the ejection fraction has increased in the recovered patients by 7.73 ± 4.37% as compared to 1.13 ± 4.20% in non-recovered patients (p=0.012)). Recovered patients have also exhibited significant improvement in 123I-MIBG uptake parameters which were correlated significantly with changes in catecholamine levels. Further, recovered patients had higher percentage of norepinephrine transporter immunoreactive nerve fibers per total area in the left ventricular apex as compared to non-recovered patients and the concentration correlated positively with recovery. In conclusion, LVAD and drug combination therapy has a positive impact on myocardial function and the cardiac nervous system which were more enhanced in the recovered subpopulation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Babies and machines that go 'beep': first year nursing students' preferred areas of future practice

Students of nursing enter their programmes of study with preconceived ideas of what a career in their chosen profession will entail. The literature suggests that images from the media and past experiences contribute to these perceptions. Although it is positive images of the profession that will usually attract an individual to a career in nursing, often more negative perceptions will direct students away from potentially rewarding areas of specialization. This paper describes career projections of nursing students enrolled in the first year of four preservice nursing programmes at the rural campus of one Australian university. Part of a larger study, the data reported here indicate that most respondents intend to practice in the areas of midwifery, paediatrics and emergency nursing. Oncology, community nursing, aged care and mental health nursing all ranked poorly across three rounds of surveys. These findings have implications for practicing nurses and nurse educators who seek to dispel inaccurate images of these important specializations