Concordance between superficial swab and deep sampling in post-sternotomy mediastinitis: Single center experience.

OBJECTIVES: Deep sampling (DS) is the gold standard for microbiological diagnosis of post-sternotomy mediastinitis (PSM), however superficial swab (SS) are frequently performed in some centers and antibiotherapy initiated base on their results. We analysed the concordance between superficial swab and deep sampling in PSM. MATERIALS AND METHODS: We analysed retrospectively patients with a PSM between 2010 and 2014 at Saint-Luc University hospital (Belgium). We considered that there was a concordance between SS and DS when the same microorganism was found in the two sampling method in each patient. Patients were stratified in six groups according to microbiology results as Staphylococcus Aureus (SA) sensitive or resistant, coagulase negative Staphylococcus (CoNS), Gram negative bacilli (GNB), other Gram positive bacteria (GPB) and fungi. RESULTS: Thirty-six patients were included. Twenty-five men (69%) and a mean age of 66 years old. The overall concordance between SS and DS was 57%. SA and GNB showed high concordance (100% and 85.7% respectively). For the other groups the concordance was low. The sensitivity and specificity of SS was 97% and 33% respectively. The PPV and NPV of superficial swab was 96% and 50% respectively. CONCLUSION: Microbiological results from SS, even with flocked swabs, except for SA and GNB have low concordance with those obtained from deep sampling. Our data confirm that in PSM, deep sampling is the gold standard for microbiological assessment.

Myocardial strain imaging: review of general principles, validation, and sources of discrepancies.

Myocardial tissue tracking imaging techniques have been developed for a more accurate evaluation of myocardial deformation (i.e. strain), with the potential to overcome the limitations of ejection fraction (EF) and to contribute, incremental to EF, to the diagnosis and prognosis in cardiac diseases. While most of the deformation imaging techniques are based on the similar principles of detecting and tracking specific patterns within an image, there are intra- and inter-imaging modality inconsistencies limiting the wide clinical applicability of strain. In this review, we aimed to describe the particularities of the echocardiographic and cardiac magnetic resonance deformation techniques, in order to understand the discrepancies in strain measurement, focusing on the potential sources of variation: related to the software used to analyse the data, to the different physics of image acquisition and the different principles of 2D vs. 3D approaches. As strain measurements are not interchangeable, it is highly desirable to work with validated strain assessment tools, in order to derive information from evidence-based data. There is, however, a lack of solid validation of the current tissue tracking techniques, as only a few of the commercial deformation imaging softwares have been properly investigated. We have, therefore, addressed in this review the neglected issue of suboptimal validation of tissue tracking techniques, in order to advocate for this matter.

Counter-intuitive plasma vitamin D and zinc status in HIV-1-infected adults with persistent low-level viraemia after treatment initiation: a pilot case-control study.

Determinants of persistent low-level viraemia [PLLV, a viral load (VL) of between 50 and 500 copies/mL] have not been elucidated. In a case-control study, we evaluated the influence of micronutrients on PLLV in a population of 454 HIV-1 adults having initiated antiretroviral therapy (ART) between January 2007 and December 2011. Plasma levels of retinol (vitamin A), 25-OH vitamin D2 + D3, vitamin E and zinc were measured at ART initiation in cases (PLLV after 6 months of ART) and in controls (VL <50 copies/mL after 6 months). Cases and controls were matched for the CD4 cell count (±50/mm3) and ethnic origin. Intergroup differences in demographic, biological and treatment parameters and sunshine intensity at ART initiation were adjusted using a propensity score. A receiver operating characteristic (ROC) curve was used to assess intergroup differences in plasma micronutrient levels. Thirty-three of the 454 patients (7.3%) displayed PLLV (median VL: 92 copies/mL). Patients were predominantly male (89%), Caucasian (64%) and CDC stage C (25%). The median age was 38 years, the median initial VL was 5.2 log10 copies/mL and the median CD4 count was 74/mm3. The 22 cases and matched controls were balanced in these respects, and had similar vitamin A/E levels. Two cases (9%) and 9 controls (41%) had a vitamin D level <10.3 ng/mL (p = 0.0015), and 2 cases (9%) and 10 controls (48%) had a zinc level <74.6 µg/dL (p = 0.04). Our results support in vitro studies suggesting that vitamin D favours HIV-1 replication and that HIV-1 is zinc-dependent. Wide-scale, prospective studies are required.

[A case of neurological syphilis mimicking Horton's disease and polymyalgia rheumatica]. / Syphilis neurologique révélée par un tableau évocateur d'artérite temporale et de pseudopolyarthrite rhizomélique.

BACKGROUND: Syphilis has been making a comeback over the last 10 years. Neurosyphilis can occur at any stage of the infection but is difficult to diagnose because of the existence of misleading forms, of which we describe an example below. PATIENTS AND METHODS: A 56-year-old woman presented symptoms evoking polymyalgia rheumatica and giant-cell arteritis in a context of ibuprofen treatment for a few weeks. She also had myodesospsia, syphilids and syphilitic roseola, together with laboratory indicators of inflammation. A lumbar puncture revealed lymphocytic meningitis and a positive Treponema Pallidum Haemagglutination Assay (TPHA) for cerebrospinal fluid, thus confirming the diagnosis of neurosyphilis. Moreover, the ophthalmologic examination showed optic neuritis with papilla lesions of syphilitic origin. This was successfully treated with a 3-week course of penicillin G infusions. CONCLUSION: Symptoms evocative of Horton's disease and polymyalgia rheumatica can reveal syphilis, a disease dubbed "the great simulator" on account of the variety of clinical forms it can take.

Characteristics and prognosis in patients with prosthetic vascular graft infection: a prospective observational cohort study.

Prosthetic vascular graft infection (PVGI) is a devastating complication, with a mortality rate of up to 75%, which is especially caused by aortic graft infection. The purpose of this study was to evaluate factors associated with in-hospital mortality of patients with definite graft infection, and with long-term outcome. We reviewed medical records of 85 patients treated for PVGIs defined by positive bacterial culture of intraoperative specimens or blood samples, and/or clinical, biological and radiological signs of infection. In-hospital patient mortality was defined as any death occurring during the initial treatment of the graft infection. Cure was defined as the absence of evidence of relapsing infection during long-term follow-up (≥1 year). Eighty-five patients (54 aortic and 31 limb graft infections) treated by surgical debridement and removal of the infected prosthesis (n=41), surgical debridement without removal of prosthesis (n=34) or antimicrobial treatment without surgery (n=10) were studied. The only microbiological difference observed between patients with early (occurring within 4 months after surgery) vs. late PVGI and between those with aortic vs. limb PVGI was the incidence of PVGI caused by Staphylococcus aureus, which was greater in patients with limb PVGI. Overall cure was observed in 93.2% of 59 patients with a follow-up of a minimum of 1 year. Overall in-hospital mortality was 16.5% (n=14). Two variables were independently associated with mortality: age >70 years (OR 9.1, 95% CI 1.83-45.43, p 0.007) and aortic graft infection (OR 5.6, 95% CI 1.1-28.7, p 0.037).

Impact of prosthesis-patient mismatch on mitral regurgitation after aortic valve replacement.

BACKGROUND: Mitral regurgitation is frequently observed in patients undergoing aortic valve replacement (AVR) for aortic stenosis and often improves postoperatively, mainly due to left ventricular remodelling and changes in loading conditions. Aortic prosthesis-patient mismatch (PPM) is associated with poor outcome and lesser left ventricular remodelling. This study tested the hypothesis that aortic PPM affects mitral regurgitation. METHODS AND RESULTS: Echocardiography was performed preoperatively and before discharge in 42 patients with aortic stenosis undergoing isolated AVR and presenting mitral regurgitation with an effective regurgitant orifice (ERO) of 10 mm(2) or greater, as assessed by the proximal isovelocity surface area method. Postoperatively, mitral ERO and the regurgitant volume decreased from 16±5mm(2) to 12±6mm(2) (p<0.001) and from 28±8ml to 16±9ml (p<0.0001), respectively. PPM (indexed effective prosthetic valve area (EOAi) ≤0.85cm(2)/m(2)), present in 23 patients (55%), was associated with a smaller decrease in regurgitant volume (p=0.0025) and ERO (p=0.02). A functional aetiology of mitral regurgitation was associated with a larger improvement in mitral regurgitation. In the whole cohort, EOAi correlated with the changes in mitral regurgitation severity (ERO r=0.44, p=0.01; regurgitant volume r=0.47, p=0.003). However, these relationships were no longer significant in the subset of patients with functional mitral regurgitation in whom mitral regurgitation changes were mainly related to postoperative changes in mitral valve deformation. CONCLUSIONS: The presence of PPM after AVR attenuates postoperative mitral regurgitation changes, mainly in patients with organic mitral regurgitation.

Efficacy and tolerance of rifampicin-linezolid compared with rifampicin-cotrimoxazole combinations in prolonged oral therapy for bone and joint infections.

Both linezolid and cotrimoxazole are antibiotics that are well suited for oral therapy of bone and joint infections (BJI) caused by otherwise resistant Gram-positive cocci (GPC) (resistance to fluoroquinolones, maccolides, betalactamines). However, in this context, no data are currently available regarding the safety and tolerance of these antibiotics in combination with rifampicin. The objective of this study was to compare the efficacy and safety of a combination of rifampicin and linezolid (RLC) with those of a combination of rifampicin and cotrimoxazole (RCC) in the treatment of BJI. Between February 2002 and December 2006, 56 adult patients (RLC, n = 28; RCC, n = 28), including 36 with infected orthopaedic devices (RLC, n = 18; RCC, n = 18) and 20 with chronic osteomyelitis (RLC, n = 10; RCC, n = 10), were found to be eligible for inclusion in this study. Patients who discontinued antibiotic therapy within 4 weeks of commencing treatment were considered to represent cases of treatment failure and were excluded. Rates of occurrence of adverse effects were similar in the two groups, at 42.9% in the RLC group and 46.4% in the RCC group (p = 1.00), and led to treatment discontinuation in four (14.3%) RLC and six (21.4%) RCC patients. Cure rates were found to be similar in the two groups (RLC, 89.3%, RCC, 78.6%; p = 0.47). Prolonged oral RLC and RCC therapy were found to be equally effective in treating patients with BJI caused by resistant GPC, including patients with infected orthopaedic devices. However, the lower cost of cotrimoxazole compared with linezolid renders RCC an attractive treatment alternative to RLC. Further larger clinical studies are warranted to confirm these preliminary results.

[Pneumonia in a traveller coming back from Asia]. / Pneumonie chez un voyageur au retour d'Asie.

A case of Salmonella paratyphi A infection was diagnosed late in a patient treated for febrile pneumonia after his returning from India. This case was remarkable in two aspects: first, it illustrated the reemergence of S.paratyphi A infections in people having traveled to India, with increasing fluoroquinolone resistance, and second the difficulty of diagnosing this disease, since the patient was initially treated for pneumonia and flu-like syndrome. Salmonella typhi or paratyphi infections should be evoked in case of persistent fever in patients having traveled to endemic areas, even if digestive signs are absent. Furthermore, choosing an empiric antibiotic treatment with fluoroquinolones could lead to treatment failure if the patient traveled in a country where fluoroquinolone resistance is high, as in Asia and especially in India.

Assessment of left ventricular mass and volumes by three-dimensional echocardiography in patients with or without wall motion abnormalities: comparison against cine magnetic resonance imaging.

AIM: To evaluate if three-dimensional echocardiography (3-DE) is as accurate and reproducible as cine magnetic resonance imaging (cMR) in estimating left ventricular (LV) parameters in patients with and without wall motion abnormalities (WMA). METHODS: 83 patients (33 with WMA) underwent 3-DE and cMR. 3-DE datasets were analysed using a semi-automatic contour detection algorithm. The accuracy of 3-DE was tested against cMR in the two groups of patients. All measurements were made twice by two different observers. RESULTS: LV mass by 3-DE was similar to that obtained by cMR (149 (SD 42) g vs 148 (45) g, p = 0.67), with small bias (1 (28) g) and excellent interobserver agreement (-2 (31) g vs 4 (26) g). The two measurements were also highly correlated (r = 0.94), irrespective of WMA. End-diastolic and end-systolic LV volumes and ejection fraction by 3-DE and cMR were highly correlated (r = 0.97, 0.98, 0.94, respectively). Yet, 3-DE underestimated cMR end-diastolic volumes (167 (68) ml vs 187 (70) ml, p<0.001) and end-systolic volumes (88 (56) ml vs 101 (65) ml, p<0.001), but yielded similar ejection fractions (50% (14%) vs 50% (16%), p = 0.23). CONCLUSION: 3-DE permits accurate determination of LV mass and volumes irrespective of the presence or absence of WMA. LV parameters obtained by 3-DE are also as reproducible as those obtained by cMR. This suggests that 3-DE can be used to follow up patients with LV hypertrophy and/or remodelling.

Coronary in-stent restenosis in diabetic patients after implantation of sirolimus or paclitaxel drug-eluting coronary stents.

It is now emerging that, in patients who are at high risk for cardiovascular complications and, in particular, those with diabetes, the occurrence of late restenosis and thrombosis after treatment of coronary artery disease with drug-eluting stents is higher than earlier reports have suggested. Therefore, the aim of this study was to assess the prevalence of in-stent restenosis in a cohort of consecutive patients with diabetes treated for coronary disease in 2005 with drug-eluting stents [either sirolimus (58%) or paclitaxel (42%)]. The duration of follow-up was 9.0+/-3.4 months [mean+/-1 standard deviation (S.D.)]. A total of 154 patients (type 2 diabetes: 91%) were included in the study (age: 66+/-10 years), and the total number of implanted stents was 184. Two subjects died from cardiac causes, while myocardial infarction and (un)stable angina were observed in 3 (2%) and 39 (25%) patients, respectively. In-stent restenosis, appraised by angiography, was observed in 17 individuals (11%) after a mean follow-up of five months. Mean HbA(1c) in patients with restenosis was 7.6+/-1.8%. There was no difference in the rate of restenosis with sirolimus-(n=8) compared with paclitaxel-(n=9) eluting stents. Male gender, oral therapy for diabetes and stent diameter were predictors of in-stent restenosis. In conclusion, even over a medium-term period, in-stent restenosis remains a potential risk for coronary diabetic patients treated with drug-eluting devices.

Long term outcome up to 30 years after the Mustard or Senning operation: a nationwide multicentre study in Belgium.

OBJECTIVE: To assess long term outcome of patients who underwent Mustard or Senning repair for transposition of the great arteries up to 30 years earlier. DESIGN: Retrospective review of medical records. SETTING: The six university hospitals in Belgium with paediatric cardiology departments. PATIENTS: 339 patients were reviewed, of whom 124 underwent the Mustard procedure and 215 the Senning procedure. This represents almost the entire population of patients in Belgium with either simple or complex transposition. MAIN OUTCOME MEASURES: Mortality, morbidity, functional abilities, social integration. RESULTS: Overall mortality was 24.2%. Early mortality (< or = 30 days after surgery) accounted for 16.5%, late mortality for 7.7%. Actuarial survival of early survivors at 10, 20, and 30 years after surgery was 91.7%, 88.6%, and 79.3%, respectively. Patients in the Senning cohort had a slightly better survival rate than those in the Mustard cohort (NS). Baffle obstruction occurred more often after Mustard repair (15.3%) than after the Senning procedure (1.4%). Arrhythmia-free survival did not differ between the two cohorts, but was determined by the complexity of the transposition. Survivors of the Senning cohort had better functional status, and tended to engage in more sports activities. CONCLUSIONS: The long term outcome for patients surviving the Mustard or Senning operation was favourable in terms of late mortality, morbidity, functional, and social status. Overall mortality in the Senning cohort did not differ from the Mustard group, but Senning patients had better functional status, greater participation in sports activities, and fewer baffle related problems.

Predictive value of markers of myocardial reperfusion in acute myocardial infarction for follow-up left ventricular function.

This study evaluated recently suggested invasive and noninvasive parameters of myocardial reperfusion after acute myocardial infarction (AMI), assessing their predictive value for left ventricular function 4 weeks after AMI and reperfusion defined by myocardial contrast echocardiography (MCE). In 38 patients, angiographic myocardial blush grade, corrected Thrombolysis In Myocardial Infarction frame count, ST-segment elevation index, and coronary flow reserve (n = 25) were determined immediately after primary percutaneous transluminal coronary angioplasty (PTCA) for first AMI, and intravenous MCE was determined before, and at 1 and 24 hours after PTCA to evaluate myocardial reperfusion. Results were related to global wall motion index (GWMI) at 4 weeks. MCE 1 hour after PTCA showed good correlation with GWMI at 4 weeks (r = 0.684, p <0.001) and was in an analysis of variance the best parameter to predict GWMI 4 weeks after AMI. The ST-segment elevation index was close in its predictive value. Considering only invasive parameters of reperfusion myocardial blush grade was the best predictor of GWMI at 4 weeks (R(2) = 0.3107, p <0.001). A MCE perfusion defect size at 24 hours of > or =50% of the MCE perfusion defect size before PTCA was used to define myocardial nonreperfusion. In a multivariate analysis, low myocardial blush grade class was the best predictor of nonreperfusion defined by MCE. Thus, intravenous MCE allows better prediction of left ventricular function 4 weeks after AMI than other evaluated parameters of myocardial reperfusion. Myocardial blush grade is the best predictor of nonreperfusion defined by MCE and is the invasive parameter with the greatest predictive value for left ventricular function after AMI. Coronary flow parameters are less predictive.

Destruction of contrast microbubbles by ultrasound: effects on myocardial function, coronary perfusion pressure, and microvascular integrity.

BACKGROUND: Recent experimental data indicate that ultrasound-induced destruction of ultrasound contrast microbubbles can cause immediate rupture of the microvessels in which these microbubbles are located. METHODS AND RESULTS: To examine the functional and morphological significance of these findings in the heart, isolated rabbit hearts were perfused retrogradely with buffer containing ultrasound contrast agents and were insolated at increasing levels of acoustic energy with a broadband transducer emitting at 1.8 MHz and receiving at 3.6 MHz and operated in the triggered mode (1 Hz). At the end of each experiment, the hearts were fixed in glutaraldehyde and examined with light microscopy. Neither exposure to ultrasound alone or to contrast alone affected left ventricular developed pressure. By contrast, simultaneous exposure to contrast and ultrasound resulted in a reversible, transient mechanical index (MI)-dependent decrease in left ventricular developed pressure (to 83+/-5% of baseline at an MI of 1.6) and a transient MI-dependent increase in coronary perfusion pressure (to 120+/-6% of baseline at an MI of 1.6). Myocardial lactate release also showed significant increases with increasing MIs. Macroscopically, areas of intramural hemorrhage were identified over the beam elevation in hearts exposed to both contrast and high-MI ultrasound. Light microscopy revealed the presence of capillary ruptures, erythrocyte extravasation, and endothelial cell damage. The mean percentage of capillaries ruptured at an MI of 1.6 was 3.6+/-1.4%. CONCLUSIONS: Simultaneous exposure of isolated rabbit hearts to ultrasound and contrast agents results in an MI-dependent, transient depression of left ventricular contractile function, a rise in coronary perfusion pressure, an increase in lactate production, and limited capillary ruptures.

Effect of cardiac output on mitral valve area in patients with mitral stenosis: validation and pitfalls of the pressure half-time method.

BACKGROUND AND AIM OF THE STUDY: The non-invasive evaluation of mitral valve area is often used in the assessment of patients with mitral stenosis. The pressure half-time method is commonly used to calculate valve area, but is inaccurate in many clinical scenarios. We sought to quantify the effects of changing cardiac output on the accuracy of mitral valve area determination. METHODS: Thirteen patients with mitral stenosis underwent routine stress echocardiography with resting and peak exercise results compared. A previously described and clinically validated mathematical model of the cardiovascular system was used to validate the clinical results. Seven different loading conditions for each of four different stenotic valve areas were modeled. RESULTS: In patients, with increasing cardiac output, pressure half-time decreased (-30.6+/-35.3 ms/l/min) and calculated valve area increased by 0.25+/-0.30 cm2/l/min. By continuity, it appeared that approximately half of this increase was due to actual valve orifice stretching, the remainder reflecting fundamental changes in the relationship between half-time and valve area. Mathematical modeling resulted in similar changes in pressure half-time and calculated valve area (0.06 to 0.12 cm2/l/min, p = 0.20 versus clinical results). CONCLUSION: Changes in cardiac output result in predictable changes in pressure half-time, and should be considered when performing serial examinations in patients with mitral stenosis.

Correlation of myocardial Doppler velocity response to exercise with independent evidence of myocardial ischemia by dual-isotope single-photon emission computed tomography.

Myocardial Doppler velocity (MDV) imaging may provide an objective correlate of ischemia, thereby reducing the expertise needed for interpreting stress echocardiography and improving its reproducibility. This study sought to independently validate the results of exercise MDV imaging with single-photon emission computed tomography (SPECT) perfusion imaging in 116 patients (age 60+/-12 years, 28 women) referred for exercise SPECT for diagnostic or prognostic assessment of coronary artery disease. Two-dimensional echocardiography was performed with simultaneous color MDV data acquisition before and after exercise treadmill testing. MDV data were processed off-line to display myocardial velocity profiles in each segment at rest and peak exercise. SPECT was analyzed using a 16-segment model and segments were classified as normal or showing resting or stress defects. Resting defects within segments showing normal function were attributed to attenuation. Color MDV data were compared with SPECT results, and a multivariate analysis (including exercise and SPECT results) was performed to identify the determinants of the exercise MDV response. Patients exercised maximally (peak rate-pressure product 27.6+/-6.1x10(3), and SPECT was abnormal in 33 patients. Of the 1,333 left ventricular segments evaluable by SPECT and MDV, 1,217 segments were classified as normal, 43 showed a stress defect, and 73 a rest defect. Segmental comparison of thallium findings and MDV showed that segments with a rest defect had a lower velocity at rest and stress than normal segments (p<0.001). Segments with a stress defect had a marked reduction in peak exercise velocity and less increment in velocity than normal segments. Heart rate, functional capacity, and presence of abnormally perfused segments were independent predictors of myocardial velocity at peak exercise. Thus, color MDV correlates with independent evidence of ischemia, although it is also influenced by exercise capacity and left ventricular function. This technique may permit a feasible approach to quantitation of exercise echocardiography.

Exercise echocardiography predicts development of left ventricular dysfunction in medically and surgically treated patients with asymptomatic severe aortic regurgitation.

OBJECTIVE: To assess resting and exercise echocardiography for prediction of left ventricular dysfunction in patients with significant asymptomatic aortic regurgitation. DESIGN: Cohort study of patients with aortic regurgitation. SETTING: Tertiary referral centre specialising in valvar surgery. PATIENTS: 61 patients (38 men, 23 women; mean (SD) age 53 (14) years) with asymptomatic or minimally symptomatic aortic regurgitation and no known coronary artery disease; 35 were treated medically and 26 had aortic valve replacement. INTERVENTIONS: Exercise echocardiography was used to evaluate ejection fraction, which was measured on the resting and post-stress images using the modified Simpson method. Patients with an increment of ejection fraction after exercise were denoted as having contractile reserve (CR+); those without an increment were labelled CR-. MAIN OUTCOME MEASURES: Standard univariate and multivariate methods and receiver operating characteristic analyses were used to assess the ability of contractile reserve to predict follow up ejection fraction. RESULTS: In the 35 medically treated patients, 13 of 21 (62%) with CR+ (mean (SD) ejection fraction increment 7 (3)%) had preserved ejection fraction on follow up. In the 14 patients with CR- (ejection fraction decrement 8 (4)%), 13 (93%) had a decrement of ejection fraction on follow up from 60 (5)% at baseline to 54 (3)% on follow up (p = 0.005). Age, resting left ventricular dimensions, medical treatment, aortic regurgitation severity, exercise capacity, and rate-pressure product were similar in both CR+ and CR- groups. Among the 26 surgical patients, 13 showed CR+ (ejection fraction increase 9 (5)%), all of whom had an increase in ejection fraction on follow up (from 49% to 59%). Of 13 surgical patients with CR- (ejection fraction decrease 7 (5)%), 10 (77%) showed the same or worse ejection fraction on postoperative follow up. CONCLUSIONS: Contractile reserve on exercise echocardiography is a better predictor of left ventricular decompensation than resting indices in asymptomatic patients with aortic regurgitation. In patients undergoing aortic valve replacement, contractile reserve had a better correlation with resting ejection fraction on postoperative follow up. Measurement of contractile reserve may be useful to monitor the early development of myocardial dysfunction in asymptomatic patients with aortic regurgitation, and may help to optimise the timing of surgery.

Use of peak systolic strain as an index of regional left ventricular function: comparison with tissue Doppler velocity during dobutamine stress and myocardial ischemia.

OBJECTIVES: The goals of this study were to examine peak systolic strain as an index of regional function in an animal model of inotropic stress and ischemia, and to compare these results with peak systolic myocardial tissue Doppler velocity (MDV). BACKGROUND: Myocardial tissue Doppler velocity is an objective measure of regional left ventricular responses to inotropic stimulation and ischemia, but it is affected by tethering from adjacent segments and translational movement. Myocardial Doppler strain (epsilon, relative change in length) is a more local measure of contractility, which can now be derived noninvasively from MDV. METHODS: Eight dogs underwent graded dobutamine infusion followed by coronary occlusion. Epicardial 2-dimensional echocardiography and color MDV of the left ventricle were obtained and digitized from the short-axis view at baseline and with dobutamine doses of 2, 4, and 8 microg/kg per minute. These were repeated 0, 10, 20, 45, and 90 seconds after occlusion of the left anterior descending artery (LAD) (n = 3) or circumflex coronary artery (n = 5). Dobutamine was continued at 8 microg/kg per minute during coronary occlusion. The peak systolic radial MDV (cm/s) and systolic strain (epsilon(s), percent thickening) in the anterior and posterior walls were measured off-line at each stage. RESULTS: Dobutamine caused an increase in MDV (P =.0001) and epsilon(s) (P =.09) above baseline values. Coronary occlusion caused a reduction in wall motion; after 45 seconds, all nonperfused segments were hypokinetic. There was a corresponding decrease in MDV and epsilon(s), but this occurred earlier for epsilon(s), and the difference between ischemic and nonischemic segments was greater for epsilon(s) than for MDV (P <. 03). Nonischemic regions trended to an increase in epsilon(s) (compensatory hyperkinesis), whereas MDV trended downward, probably reflecting the global decrease in left ventricular function. CONCLUSION: Both MDV and epsilon(s) increase with dobutamine and decrease during ischemia. epsilon(s) appears to respond to local ischemia earlier than MDV, perhaps because it is a more local measure. Thus epsilon(s) may prove to be an accurate parameter for the clinical recognition of regional ischemia.

Individualizing the aorto-radial pressure transfer function: feasibility of a model-based approach.

We fitted a three-segment transmission line model for the radial-carotid/aorta pressure transfer function (TFF) in 31 controls and 30 patients with coronary artery disease using noninvasively measured (tonometry) radial and carotid artery pressures (P(car)). Except for the distal reflection coefficient (0.85 +/- 0.21 in patients vs. 0.71 +/- 0.25 in controls; P < 0.05), model parameters were not different between patients or controls. Parameters were not related to blood pressure, age, or heart rate. We further assessed a point-to-point averaged TFF (TFF(avg)) as well as upper (TFF(max)) and lower (TFF(min)) enveloping TFF. Pulse pressure (PP) and augmentation index (AIx) were derived on original and reconstructed P(car) (P(car,r)). TFF(avg) yielded closest morphological agreement between P(car) and P(car,r) (root mean square = 4.3 +/- 2.3 mmHg), and TTF(avg) best predicted PP (41.5 +/- 11.8 vs. 41.1 +/- 10.0 mmHg measured) and AIx (-0.02 +/- 0.19 vs. 0.01 +/- 0.19). PP and AIx, calculated from P(car) or P(car,r), were higher in patients than in controls, irrespectively of the TFF used. We conclude that 1) averaged TFF yield significant discrepancies between reconstructed and measured pressure waveforms and subsequent derived AIx; and 2) different TFFs seem to preserve the information in the pressure wave that discriminates between controls and patients.