Non-invasive assessment of cardiac output at rest and during exercise by finger plethysmography.

AIMS: We sought to determine the accuracy of finger plethysmography using pulse waveform analysis with brachial calibration for measurement of cardiac output during submaximal exercise by comparing it against an acetylene (C2H2) uptake technique. METHODS: The study included 24 healthy volunteers (12 males, age 35 ± 8 years). Testing was performed on an upright cycle ergometer using an incremental protocol. Cardiac output measurements were performed at rest and during sub-maximal exercise using a single breath C2H2 uptake technique and continuously using finger plethysmography with brachial calibration. RESULTS: Valid results at rest and during sub-maximal exercise were achieved in 20 of 24 participants. Cardiac output at rest was 5.3 ± 1.1 and 5.2 ± 1.2 l min(-1) for finger plethysmography and C2H2, respectively, P = 0.712. Mean difference between techniques was -0.1 ± 0.5 l min(-1). Cardiac output during submaximal exercise was 10.2 ± 2.3 and 10.3 ± 2.1 l min(-1) for finger plethysmography and C2H2, respectively, P = 0.898. Mean difference between techniques was 0.1 ± 1.5 l min(-1). The overall correlation between finger plethysmography and C2H2 data obtained during rest and exercise was r(2) = 0.872, P<0.0001. Mean rise in cardiac output during exercise was 4.9 ± 1.5 (finger plethysmography) and 5.1 ± 1.5 l min(-1) (C2H2), P = 0.64. CONCLUSION: Finger plethysmography determined cardiac output values both at rest and during sub-maximal exercise are comparable with those obtained using a single breath C2H2 uptake technique.

Successful treatment of rotary pump thrombus with the glycoprotein IIb/IIIa inhibitor tirofiban.

Despite advances in blood pump technology, thrombus formation within left ventricular assist devices (LVADs) is a life-threatening complication with few therapeutic options. A 38-year-old woman who underwent rotary LVAD implantation as a bridge to cardiac transplant developed labile flows (4 to >10 liters), associated with power spikes (4 to 12 watts) and an increase in plasma free hemoglobin (0.86 g/liter), consistent with pump thrombus at Day 140 post-LVAD implantation, despite thromboprophylaxis with aspirin and warfarin. Within 12 hours of commencing an intravenous infusion of tirofiban at a rate of 0.1 mug/kg/min, there were signs of improvement of pump dysfunction, and complete resolution was evident at Day 4 with, stable flows, power consumption and normalization of plasma free hemoglobin. Tirofiban may be considered as an alternative thrombolytic treatment strategy in rotary pump thrombus to avoid the need for LVAD replacement.

Time course for recovery of atrial mechanical and endocrine function post DC cardioversion for persistent atrial fibrillation.

We prospectively determined the time course of recovery of atrial mechanical and endocrine function in patients following DC cardioversion for persistent atrial fibrillation (AF). Twenty-three consecutive patients underwent successful DC cardioversion (mean age 64 years, 20 male). By 28 days, nine had reverted to atrial fibrillation. Recovery of atrial mechanical (peak A wave velocity) and endocrine function (atrial natriuretic peptide, ANP) were assessed at four time points: immediately pre-cardioversion, and then 4 h, 7 and 28 days post. The 14 patients maintaining sinus rhythm formed the success group. In this group, peak A wave velocity increased significantly over time from 0.28+/-0.03 m/s (mean+/-S.E.M.) at 4 h to 0.50+/-0.03 m/s at day 7 and 0.67+/-0.05 m/s at day 28 (p<0.001). Plasma ANP was 150+/-34 pg/ml immediately prior to DC cardioversion in the success group. This showed an initial dip at 4 h to 44+/-9 pg/ml (p<0.001). By day 7, plasma ANP had increased to 105+/-21 pg/ml (p<0.05 vs. baseline and 4 h) and then appeared to remain constant, being 102+/-19 pg/ml at day 28 (p=0.06 vs. baseline). A similar early reduction in ANP levels was seen in the group who subsequently reverted to atrial fibrillation. Baseline ANP levels did not predict subsequent successful maintenance of sinus rhythm. Initial "stunning" in both atrial mechanical and endocrine function occurs in patients following DC cardioversion for atrial fibrillation. Whilst endocrine function appears to fully recover by day 7, mechanical function continues to improve beyond day 7.

The epidemiological enigma of heart failure with preserved systolic function.

BACKGROUND: Current epidemiological evidence suggests that the prevalence of preserved systolic function in patients with heart failure varies widely from 13 to 74%. This inconsistency suggests a lack of consensus as to what this condition really is and how it has been characterised for epidemiological studies. AIMS: In this review, we summarise and discuss the current understanding of the epidemiology of heart failure with preserved systolic function and the challenges that this raises. METHODS: Studies were identified from Medline and Embase Literature Database searches using the subject headings heart failure, diastolic heart failure, epidemiology, incidence, prevalence, diagnosis, prognosis and mortality. RESULTS: Sixty-one studies of congestive heart failure with preserved systolic function were reviewed. There is great diversity in the criteria used to determine whether heart failure is present, the patient population, the setting of the study and methods of evaluating left ventricular function. This makes epidemiological studies of prevalence, morbidity and mortality impossible to compare. CONCLUSIONS: The diagnosis of this syndrome might be better defined in terms of symptoms, elevated neuro hormones and impaired cardiac workload. This would allow accurate identification of cases so that further research could be conducted to measure outcome and assess therapeutic benefit.