Photosynthetic microbial fuel cell with polybenzimidazole membrane: synergy between bacteria and algae for wastewater removal and biorefinery.

Here, we demonstrate a very efficient simultaneous approach of bioenergy generation from wastewater and added-value compounds production by using a photosynthetic microalgae microbial fuel cells (PMFC), based on polybenzimidazole (PBI) composite membrane as separator. The use of PBI was proved to be very promising, even more convenient than Nafion™ in terms of energy performances as well as cost and sustainability. This polymer is also easily autoclavable, so allowing a re-use of the separator with a consequent beneficial cost effect. Two PMFCs were investigated: 1) Pt electrocatalysed and 2) Pt-free. They were operated as microbial carbon capture (MCC) device under continuous illumination, by using a domestic wastewater as anolyte and Scenedesmus acutus strain in the catholyte. The Pt-based cell allowed to generate higher volumetric power density (∼400 mW m-3) after more than 100 operating days. This resulted in an improved wastewater treatment efficiency, determined in terms of normalised energy recovery (NER > 0.19 kWh kgCOD-1 in case of Pt). The CO2 fixation of the PMFC-grown microalgae leaded to a high accumulation of added-value products, namely pigments and fatty acids. A significant quantity of lutein was observed as well as a relevant amount of other valuable carotenoids, as violaxanthin, astaxanthin and cantaxanthin. The lipids were even excellently accumulated (49%dw). Their profile was mainly composed by fatty acids in the range C16-18, which are particularly indicated for the biofuel production. These results demonstrate the feasibility and the implemented sustainability of such PMFCs as a great potential technology for the wastewater treatment and the simultaneous production of valuable products.

Usefulness of transoesophageal echocardiography before cardioversion in patients with atrial fibrillation and different anticoagulant regimens.

OBJECTIVES: To evaluate the prevalence of atrial thrombi in patients with atrial fibrillation undergoing different anticoagulation regimens before cardioversion; to evaluate the usefulness of transoesophageal echocardiography (TOE) guided cardioversion to prevent thromboembolic complications; and to correlate the presence of atrial thrombi with clinical and echocardiographic data. METHODS: 757 consecutive patients admitted as candidates for cardioversion of atrial fibrillation were enrolled in the study. They were divided into four groups: effective conventional oral anticoagulation, short term anticoagulation, ineffective oral anticoagulation or subtherapeutic anticoagulation, and effective oral anticoagulation with a duration of < 3 weeks for various clinical reasons. All patients underwent TOE before cardioversion; in the presence of atrial thrombi or extreme left atrial echo contrast, cardioversion was postponed. The incidence of thromboembolic events was evaluated after cardioversion. RESULTS: Atrial thrombi were detected in 48 of the 757 (6.3%) patients. No significant differences in the percentage of atrial thrombosis were found in the four study groups. Patients with atrial thrombosis were older and had a higher percentage of mitral prosthetic valves, lower left ventricular ejection fraction, more severe atrial spontaneous echo contrast, and lower Doppler left atrial appendage velocities. 648 patients were scheduled for cardioversion. Cardioversion was successful in 89% of patients without any major thromboembolic event. CONCLUSIONS: The prevalence of atrial thrombosis before cardioversion despite different treatments with anticoagulants is about 7% and a TOE guided approach may prevent the risk of embolic events.

Coronary blood flow, metabolism, and function in dysfunctional viable myocardium before and early after surgical revascularisation.

OBJECTIVES: To assess the link between perfusion, metabolism, and function in viable myocardium before and early after surgical revascularisation. DESIGN: Myocardial blood flow (MBF, thermodilution technique), metabolism (lactate, glucose, and free fatty acid extraction and fluxes), and function (transoesophageal echocardiography) were assessed in patients with critical stenosis of the left anterior descending coronary artery (LAD) before and 30 minutes after surgical revascularisation. SETTING: Tertiary cardiac centre. PATIENTS: 23 patients (mean (SEM) age 57 (1.7) years with LAD stenosis: 17 had dysfunctional viable myocardium in the LAD territory, as shown by thallium-201 rest redistribution and dobutamine stress echocardiography (group 1), and six had normally contracting myocardium (group 2). RESULTS: LAD MBF was lower in group 1 than in group 2 (58 (7) v 113 (21) ml/min, p < 0.001) before revascularisation and improved postoperatively in group 1 (129 (133) ml/min, p < 0.001) but not in group 2 (105 (20) ml/min, p = 0.26). Group 1 also had functional improvement in the LAD territory at intraoperative echocardiography (mean regional wall motion score from 2.6 (0.85) to 1.5 (0.98), p < 0.01). Oxidative metabolism, with lactate and free fatty acid extraction, was found preoperatively and postoperatively in both groups; however, lactate and free fatty acid uptake increased after revascularisation only in group 1. CONCLUSIONS: MBF is reduced and oxidative metabolism is preserved at rest in dysfunctional but viable myocardium. Surgical revascularisation yields immediate perfusion and functional improvement, and increases the uptake of lactate and free fatty acids.

Giant anastomotic pseudoaneurysm after Bentall operation causing late postoperative cardiogenic shock.

Pseudoaneurysm of the ascending aorta is a rare but severe complication occurring after composite graft surgery for combined aortic valve and ascending aorta disease. The diagnosis of this condition can be difficult because anastomotic pseudoaneurysms show highly variable clinical features depending on the site of the aortic dehiscence and on the involvement of the surrounding structures. We report an unusual case of a late postoperative aortic graft dehiscence, causing acute right heart failure.

Transesophageal echocardiography as predictor of mitral valve repair.

BACKGROUND AND AIM OF THE STUDY: Mitral valve repair has recently emerged as the treatment of choice in patients presenting with insufficiency due to valve prolapse. The study aims were to evaluate: (i) the clinical presentation in a consecutive series of patients with mitral valve prolapse undergoing surgical repair; (ii) the correlation between pre- and intraoperative echocardiographic features and surgical findings in these patients; and (iii) whether clinical and echocardiographic data may predict surgical outcome. METHODS: Between March 1997 and May 2000, 152 patients (110 men, 42 women; mean age 59+/-13 years) were recruited into the study. All patients had myxomatous mitral valve disease causing severe regurgitation and underwent systematic examination by transesophageal echocardiography (TEE) for clear delineation of the three scallops of the posterior leaflet and juxtaposed segments of the anterior leaflet. RESULTS: In 119 patients (78%) a flail valve was documented by TEE and confirmed on surgical inspection; an anterior leaflet chordal rupture was not visualized by TEE in one case. In 15 cases (10%) there was flail of the anterior leaflet, and in 105 cases (69%) flail of the posterior leaflet. A bileaflet complex prolapse without chordal rupture was found in 32 cases. On the basis of TEE evaluation, mitral valve replacement was performed electively in 10 patients (7%); the other 142 (93%) underwent mitral valve repair. Adequate repair was obtained in 93% of cases; residual mitral regurgitation (eight cases; grade 3+) and mitral stenosis (one case) were documented by intraoperative TEE, and nine patients (6%) underwent valve replacement. CONCLUSION: The majority of patients with myxomatous mitral valve prolapse and severe regurgitation undergoing valve repair have chordal rupture of the posterior mitral leaflet, a condition in which results of valve repair are excellent. TEE provides a powerful means to define the mechanisms of mitral regurgitation and to identify the suitability of patients for valvuloplasty.

Rapid diagnosis and management of thoracic aortic dissection and intramural haematoma: a prospective study of advantages of multiplane vs. biplane transoesophageal echocardiography.

AIMS: The purposes of this study were to compare the accuracy of multiplane vs. biplane transoesophageal echocardiography (TEE) in the diagnosis of aortic dissection and aortic intramural haematoma, and to test whether these techniques provide all the diagnostic information required to make management decisions. METHODS AND RESULTS: Fifty-eight consecutive patients with clinically suspected aortic dissection were studied with multiplane TEE; all cases who required surgery underwent intraoperative monitoring with multiplane TEE. The following multiplane TEE data were analysed: the angle between current and 0 degrees plane at which each view was obtained; the success rate in the evaluation of true and false lumen, entry tear, coronary artery involvement, aortic regurgitation, pericardial effusion. Advantages of multiplane over biplane TEE have been evaluated by the demonstration of usefulness of views obtained in planes other than 0 degrees-20 degrees or 70 degrees-110 degrees, assuming that with manipulation of a biplane probe a 20 degrees arc could be added to the conventional horizontal and vertical planes. On the basis of TEE findings, aortic dissection was confirmed in 36 cases (18 type A, 12 type B, six intramural haematoma). The specificity and sensitivity of TEE in terms of the presence or absence of aortic dissection or intramural haematoma were 100%. An additional clinical value of multiplane over biplane TEE in the evaluation of ascending aorta, aortic arch, entry tears and coronary artery involvement was demonstrated. All cases with type A aortic dissection or intramural haematoma involving the ascending aorta had an operation that was performed immediately after the diagnosis (hospital mortality, 13%). Patients with type B aortic dissection were treated medically; 25% of these cases were operated later (hospital mortality, 0%). CONCLUSIONS: Multiplane and biplane TEE have excellent and similar accuracies in the evaluation of aortic dissection and intramural haematoma. Multiplane TEE improves the visualization of coronary arteries, aortic arch and entry tears; it appears to be an ideal method as the sole diagnostic approach before surgery in type A aortic dissection.

Influences of aortic pressure gradient and ventricular septal thickness with systolic coronary flow in aortic valve stenosis.

This study evaluates flow patterns of the left anterior descending and circumflex coronary arteries by multiplane transesophageal echocardiography in 25 patients with aortic valve stenosis, and assesses the relation between coronary flow characteristics and anatomic and hemodynamic parameters.

Medium-term effectiveness of L-thyroxine treatment in idiopathic dilated cardiomyopathy.

BACKGROUND: In dilated cardiomyopathy, short-term administration of L-thyroxine (100 micrograms/ day) improves cardiac and exercise performance without changing the heart's adrenergic sensitivity. The aim of this study was to test the medium-term (3 months) efficacy of L-thyroxine (10 patients) compared with placebo (10 patients) and to find out whether later effects are obtainable. METHODS: Echocardiographic parameters in the control state and during acute changes of left ventricular afterload, cardiopulmonary exercise test, and hemodynamic parameters, including cardiac beta 1 responses to dobutamine, were obtained before and at the end of treatment. RESULTS: Significant (P < 0.05) changes were observed only with the active drug. After L-thyroxine, patients did not show evidence of chemical hyperthyroidism, despite the increase in thyroxine and the reduction in thyroid-stimulating hormone plasma levels. Cardiac performance improved, as shown by the increase in the left ventricular ejection fraction and rightward shift of the slope of the relation left ventricular ejection fraction/end-systolic stress. Resting cardiac output increased, and the left ventricular diastolic dimensions and systemic vascular resistances decreased. The responses of cardiac output and heart rate to dobutamine infusion were also enhanced. Functional capacity markedly improved, together with an increase in peak exercise cardiac output. CONCLUSION: L-thyroxine does not lose its beneficial effects on cardiac and exercise performance on medium-term administration and does not induce adverse effects. In addition to the short-term study, the left ventricular diastolic dimensions were decreased. An upregulation of beta 1 receptors might explain the cardiac response to dobutamine.

Intraoperative multiplane vs biplane transesophageal echocardiography for the assessment of cardiac surgery.

This study was undertaken to test whether multiplane transesophageal echocardiography (TEE) offers advantages in comparison with biplane TEE in the intraoperative monitoring during cardiac surgery. A diagnostic multiplane TEE was performed in 400 patients in the immediate preoperative and postoperative periods. We systematically acquired cardiac images from the gastric fundus, lower esophagus, and upper esophagus; complete views of the descending aorta were also recorded. Usefulness of the different views in providing essential additional clinical information compared with exclusive transverse (0 to 20 degrees) and longitudinal (70 to 110 degrees) planes of the biplane TTE was assessed assuming that with manipulation of a biplane probe, a 20 degrees are could be added to the conventional horizontal and vertical planes. A high success rate of each view was demonstrated; anatomy and pathologic condition were best visualized in oblique planes. The method proved to be particularly useful in the preoperative and postoperative phases of aortic dissection (27 cases), aortic (65 cases) and mitral (35 cases) valve replacement, mitral valve repair (38 cases), left ventricular aneurysmectomy (25 cases), bleeding from proximal suture of an aortic heterograft (2 cases), and positioning of left ventricular hemopump (2 cases). Additional regional wall motion abnormalities of the right (four cases) and left ventricle (six cases) not appreciated in 0 to 20 degrees or 70 to 110 degrees planes were detected. Multiplane TEE is a useful clinical tool during intraoperative monitoring of cardiac surgery. Most structures of the heart and great vessels lie on oblique planes, while other views are optimized with the aid of slight angle corrections. This method improves the evaluation of anatomy and pathologic condition of the heart and great vessels, of native and prosthetic valves, and of left and right ventricular function.

Evaluation of the dead space/tidal volume ratio in patients with chronic congestive heart failure.

Dead space/tidal volume ratio (VD/VT) evaluation is currently performed in patients with respiratory and cardiac disorders, and includes measurement of arterial CO2 partial pressure (PaCO2). PaCO2 is generally derived from either PETCO2 (end-expiratory CO2 pressure) or PJCO2 (calculated as PJCO2 = 5.5 + 0.9 PETCO2 - 2.1 VT). The applicability of these methods may be questionable in chronic heart failure due to its frequent association with lung dysfunction. In 63 patients with congestive heart failure, the authors compared PaCO2 versus PETCO2 and PJCO2 and VD/VT measured with PaCO2 versus VD/VT estimated with PETCO2 (estimation 1) or PJCO2 (estimation 2). Comparisons were made at rest, at submaximal exercise, and at peak exercise. Considering all 326 measurements, there was a strong correlation, but not an identity, between PaCO2 and PETCO2 (PaCO2 = 7.25 + 0.80 PETCO2, r = .84, P < .0001) and between PaCO2 and PJCO2 (PaCO2 = 6.18 + 0.84 PJCO2, r = .85, P < .0001). Results were comparable concerning PaCO2 versus PJCO2. Measured VD/VTs also strongly correlated with estimated VD/VTs (VD/VT measured = -0.03 + 1.11 VD/VT [estimation 1], r = .90, P < .0001, and VD/VT measured = 0.03 + 0.92 VD/VT [estimation 2], r = .90, P < .0001). However, only at rest and, solely for estimation 1, at submaximal exercise were the slopes and y intercepts of measured versus estimated VD/VT not different from 1 and 0, respectively; in this regard, lung dysfunction was more influential than the severity of cardiac failure. Although PaCO2 strongly correlates with PETCO2 and PJCO2, these measurements may not be reliable for a noninvasive calculation of VD/VT in chronic congestive heart failure.

Lung-heart interaction as a substrate for the improvement in exercise capacity after body fluid volume depletion in moderate congestive heart failure.

We investigated exercise capacity after fluid depletion in patients with moderate congestive heart failure (CHF). Twenty-one patients underwent ultrafiltration (mean volume +/- SEM: 1,770 +/- 135 ml). Echocardiography, tests of pulmonary function, and a cardiopulmonary exercise test with hemodynamic and esophageal pressure monitoring were performed before ultrafiltration and 3 months later. Tests without invasive measurements were repeated 4 and 30 days after ultrafiltration. Twenty-one control patients followed the same protocol but did not have ultrafiltration. Patients who underwent ultrafiltration and increased their oxygen consumption at peak exercise (peak VO2) by > 10% at the 3-month evaluation (group A1, n = 9) were separated from those who did not (group A2, n = 8); 3 patients did not complete the follow-up. Four days after the procedure, peak VO2 had risen from 17.3 +/- 0.8 to 19.3 +/- 0.9 ml/min/kg in group A1, and from 11.9 +/- 0.7 to 14.1 +/- 0.7 ml/min/kg in group A2 (p < 0.01). Plasma norepinephrine and pulmonary function were consistent with a greater severity of the syndrome in group A2. At 3 months in group A1, the relations of filling pressure to cardiac index of the right and left ventricles were shifted upward; the esophageal pressure swing (differences between end-expiratory and end-inspiratory pressure) for a given tidal volume was lower; the peak exercise dynamic lung compliance had increased from 0.10 +/- 0.05 to 0.14 +/- 0.03 L/mm Hg (p < 0.01). None of these changes were detected in group A2 and control patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary flow and left ventricular diastolic function in aortic regurgitation.

BACKGROUND: An abnormal coronary perfusion pressure is probably the major determinant of altered myocardial perfusion in aortic regurgitation; ventricular hypertrophy and diastolic function may also be involved. This study was undertaken to investigate the respective roles of these two variables. METHODS: Using multiplane transesophageal echocardiography, we evaluated the coronary Doppler flow velocity in the proximal left anterior descending coronary artery in 15 patients with aortic regurgitation before and immediately after valve replacement. The ratios of diastolic:systolic velocity integral and early:late diastolic velocity integral were correlated against coronary perfusion pressure, pulmonary wedge pressure and Doppler echocardiographic indices of left ventricular diastolic function. Patients were compared with 10 subjects without valvular diseases. RESULTS: Aortic regurgitation was associated with a reduction of the coronary diastolic:systolic velocity integral ratio and increment in the early:late diastolic velocity integral ratio. The latter correlated positively with early:late diastolic ratio of mitral flow velocity, pulmonary wedge pressure and left ventricular mass index. Soon after valve replacement, a decrease in pulmonary wedge pressure and a rise in coronary perfusion pressure were seen. Both the echo-Doppler parameters related to diastolic function and the systodiastolic distribution of coronary flow returned to normal. This indicates that diastolic dysfunction rather than left ventricular mass may be related to a disordered myocardial perfusion. CONCLUSIONS: In aortic regurgitation, a relationship exists between diastolic ventricular function and coronary flow phasic distribution. Valve replacement improves the former and normalizes the latter. Echo-Doppler parameters of diastolic dysfunction identify patients with worse coronary perfusion and might represent an additional criterion in the preoperative evaluation of patients with aortic regurgitation.

Systemic to pulmonary bronchial blood flow in heart failure.

STUDY OBJECTIVE: The aim of this study was to measure systemic to pulmonary blood flow from bronchial circulation (Qbr[s-p]) in patients with heart failure. DESIGN: In the absence of pulmonary and coronary flows, Qbr(s-p) is the volume of blood accumulating in the left side of the heart; Qbr(s-p) was measured during total cardiopulmonary bypass for coronary artery surgery; bronchial blood was vented through a cannula introduced into the left side of the heart and its volume was measured. PATIENTS: Patients were subdivided according to the presence for more than 6 months (group 1, n = 6) or less than 2 months (group 2, n = 7), or the absence of heart failure (group 2, n = 15). MEASUREMENTS AND RESULTS: Qbr(s-p) was 89 +/- 18* mL/min, 27 +/- 3, 22 +/- 2, in groups 1, 2, and 3, respectively (* = p < 0.01 group 1 vs groups 2 and 3). During total cardiopulmonary bypass, pulmonary venous pressure approximates atmospheric pressure and no differences between groups were observed in systemic artery pressure, extracorporeal circulation pump flow, and airway pressure. Therefore, vascular resistance through the bronchial vessels draining into the pulmonary circulation is reduced in patients with heart failure for more than 6 months (group 1). CONCLUSIONS: During total cardiopulmonary bypass, Qbr(s-p) is increased in patients with chronic heart failure. Since with elevated pulmonary vascular pressure blood flow through Qbr(s-p) vessels is from the pulmonary to the systemic circulation, the lower resistance observed in group 1 suggests that bronchial vessels might contribute to reduced lung fluid overload in patients with chronic heart failure.

Pericardial effusion after cardiac surgery: incidence, site, size, and haemodynamic consequences.

OBJECTIVE: To evaluate the incidence, characteristics, and haemodynamic consequences of pericardial effusion after cardiac surgery. DESIGN: Clinical, echocardiographic, and Doppler evaluations before and 8 days after cardiac surgery; with echocardiographic and Doppler follow up of patients with moderate or large pericardial effusion after operation. SETTING: Patients undergoing cardiac surgery at a tertiary centre. PATIENTS: 803 consecutive patients who had coronary artery bypass grafting (430), valve replacement (330), and other types of surgery (43). 23 were excluded because of early reoperation. MAIN OUTCOME MEASURES: Size and site of pericardial effusion evaluated by cross sectional echocardiography and signs of cardiac tamponade detected by ultrasound (right atrial and ventricular diastolic collapse, left ventricular diastolic collapse, distension of the inferior vena cava), and Doppler echocardiography (inspiratory decrease of aortic and mitral flow velocities). RESULTS: Pericardial effusion was detected in 498 (64%) of 780 patients and was more often associated with coronary artery bypass grafting than with valve replacement or other types of surgery; it was small in 68.4%, moderate in 29.8%, and large in 1.6%. Loculated effusions (57.8%) were more frequent than diffuse ones (42.2%). The size and site of effusion were related to the type of surgery. None of the small pericardial effusions increased in size; the amount of fluid decreased within a month in most patients with moderate effusion and in a few (7 patients) developed into a large effusion and cardiac tamponade. 15 individuals (1.9%) had cardiac tamponade; this event was significantly more common after valve replacement (12 patients) than after coronary artery bypass grafting (2 patients) or other types of surgery (1 patient after pulmonary embolectomy). In patients with cardiac tamponade aortic and mitral flow velocities invariably decreased during inspiration; the echocardiographic signs were less reliable. CONCLUSIONS: Pericardial effusion after cardiac surgery is common and its size and site are related to the type of surgery. Cardiac tamponade is rare and is more common in patients receiving oral anticoagulants. Echo-Doppler imaging is useful for the evaluation of pericardial fluid accumulations after cardiac surgery. It can identify effusions that herald cardiac tamponade.

Long-term use of K-strophanthin in advanced congestive heart failure due to dilated cardiomyopathy: a double-blind crossover evaluation versus digoxin.

K-strophanthin or digoxin were added to diuretics (all cases) and vasodilators (most cases) for treating advanced congestive heart failure in 22 patients with dilated cardiomyopathy and sinus rhythm. K-strophanthin (0.125 mg intravenously) or digoxin (0.25 mg orally) were administered daily in two 3-month periods, during which vasodilators and diuretics were kept constant and patients received one of the two digitalis preparations in a double-blind fashion, crossing over to the alternative preparation in the next period. Blindness was assured throughout the trial with a daily intravenous injection of 10 ml normal saline solution either containing K-strophanthin or not, and with daily oral administration of either placebo or active digoxin. At the end of the run-in period, 15 days after starting active preparations, and thereafter every month for the next 6 months, we evaluated left ventricular pump function at rest and patients' functional performance by a cardiopulmonary exercise test. At Day 15, cardiac index and ejection fraction at rest, compared with run-in, were significantly raised with both glycosides; during exercise while on K-strophanthin, peak oxygen consumption was augmented by 1.4 ml/min/kg (p < 0.01) and oxygen consumption at anaerobic threshold by 2.2 ml/min/kg (p < 0.01); corresponding variations on digoxin (-0.1 and +0.3, respectively) were not significant versus run-in. These patterns were duplicated at repeated tests during follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

[Multiplane transesophageal echocardiography for the monitoring of cardiac surgery]. / L'ecocardiografia transesofagea multiplana per il monitoraggio di interventi di cardiochirurgia.

Multiplane transesophageal echocardiography (TEE) allows visualization of the heart and great vessels through an infinite number of imaging planes and improves the diagnostic capabilities of mono and biplane TEE. This study was undertaken to test whether MTEE is a useful intraoperative monitoring method during cardiac surgery. Intraoperative multiplane TEE was performed in 200 patients (mean age 56 +/- 19 years) as a part of the routine clinical care. We systematically acquired cardiac images from the gastric fundus (short and long axes of the ventricles), lower esophagus (four-chamber, two-chamber, and long axis), upper esophagus (13 views concerning the aorta, pulmonary artery, left and right atrium, systemic and pulmonary veins, coronary arteries, right ventricular outflow tract), and searched for complete views of the thoracic descending aorta. All views analyzed in the preoperative (immediately before cardiopulmonary bypass), intraoperative and postoperative phases evaluating: the angle between current and 0 degree at which each view was obtained; the success rate of each view; the usefulness of the different views in providing essential additional clinical information compared to 0 degrees and 90 degrees of the traditional biplane TEE. Most views of the heart and great vessels were visualized in oblique planes, and other views were significantly improved thanks to slight angle corrections. Multiplane TEE was particularly useful in the preoperative and postoperative phases of aortic dissection (11 cases), mitral valve repair (13 cases), left ventricular aneurysmectomy (9 cases), right atrial thrombosis (1 case), positioning of left ventricular hemopump (2 cases), mitral-aortic endocarditis (3 cases), bleeding from proximal suture of an aortic heterograft (1 case).(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of L-thyroxine to improve cardiac and exercise performance in idiopathic dilated cardiomyopathy.

The short-term effects of L-thyroxine (100 micrograms/day, 10 patients) and placebo (10 patients) on idiopathic dilated cardiomyopathy were compared. Before and at the end of the treatment, a hemodynamic study was performed in the control state and during dobutamine infusion. A cardiopulmonary exercise test was also performed with hemodynamic monitoring. An echocardiogram was recorded in the control state and during acute changes of left ventricular afterload. Plasma levels of triiodothyronine, thyroxine, thyroid-stimulating hormone and norepinephrine were measured. Placebo was ineffective. After administration of L-thyroxine all patients had normal thyroid function. The increase in left ventricular ejection fraction and the rightward shift of the slope of left ventricular ejection fraction/end-systolic stress relation (p < 0.05) indicated an improvement in the cardiac inotropic state. This proved to be independent of adrenergic influences by the unchanged beta 1 response to dobutamine. A decrease in resting systemic vascular resistances and an increase in cardiac output (p < 0.05) were also observed. Cardiopulmonary effort parameters improved (p < 0.05) without hemodynamic changes at peak exercise. It is concluded that L-thyroxine short-term administration improves cardiac and exercise performance in patients with chronic heart failure, without modifying the adrenergic support to the heart and the circulatory parameters at peak exercise.

[Transesophageal coronary flowmetry and ventricular diastolic properties in surgically treated aortic insufficiency]. / Flussimetria coronarica transesofagea e proprietà diastoliche ventricolari nell'insufficienza aortica trattata chirurgicamente.

In patients with aortic valve regurgitation anginal pain without coronary artery disease is a consequence of both impairment of coronary flow (CF) reserve and reduction of diastolic CF (D) due to a diminished coronary perfusion pressure (CPP). Aim of this study was to evaluate with transesophageal multiplane echocardiography CF pattern in 15 patients with severe aortic regurgitation (AR) in the operative room before and after aortic valve replacement and to correlate it with hemodynamic parameters of left ventricular systolic (echocardiographic fractional shortening area) and diastolic (Doppler E/A ratio of mitral flow and X/Y ratio of pulmonary venous flow; pulmonary wedge pressure) function. Patients were compared to a control group (C) of 10 subjects. Coronary flow was divided into systolic (S), protodiastolic (PD) and end-diastolic (ED) components. In AR we observed a reduction in D/S ratio (2.6 +/- 1.3 versus 3.5 +/- 0.8, NS) and an increase in PD/ED ratio (2.24 +/- 2.8 versus 1.05 +/- 0.15, p < 0.001). A positive correlation was observed between PD/ED ratio and left ventricular diastolic impairment (E/A ratio: r = 0.71, p < 0.001; wedge pressure: r = 0.70, p < 0.001) and a negative correlation with CPP (r = -0.6, p < 0.02). Forty-five min after aortic valve replacement diastolic function improvement and CPP increase were associated with a normalization of CF pattern (D/S = 4.35 +/- 1.9/PD/ED = 1.06 +/- 0.16). In conclusion in AR diastolic dysfunction and abnormal CPP are strictly related to the reduction in diastolic CF; valve replacement normalizes the former two parameters and redistributes CF in late diastole.

A new formula for echo-Doppler estimation of right ventricular systolic pressure.

The Doppler formulas currently used for right ventricular systolic pressure (RVSP) evaluation include right ventricular-right atrial (RV-RA) gradient and RA pressure. The former is expressed by the velocity of the trans-tricuspid regurgitant flow; the latter is generally assumed and is different from one formula to another. In 110 patients with cardiac disease with normal or elevated pulmonary pressure, we tested a new echo-Doppler formula for the evaluation of RVSP based on the estimation of RA pressure by means of the inferior vena cava collapsibility index (IVCCI) and compared this method with two traditional formulas (methods A and B) and with cardiac catheterization values. Patients were classified into three groups on the basis of IVCCI (group 1 > 45%, group 2 between 35% and 45%, and group 3 < 35%). RVSP was evaluated by method A (RV-RA gradient + 10), method B (RV-RA gradient x 1.1 + 14), and our new method, method C, which assigns 6, 9, and 16 mmHg to RA pressure in the presence of normal (> 45%), moderately reduced (between 35% and 45%), or markedly reduced (< 35%) IVCCI, respectively. IVCCI correctly identified RA pressure in the three groups (group 1, 6.8 mmHg; group 2, 10.8 mm Hg; and group 3, 13.1 mmHg); a high correlation existed between Doppler-derived and invasively determined RV-RA gradient (r = 0.99). Method C improved noninvasive estimation of RVSP in groups 1 and 3 compared with the other methods; in group 2, Doppler estimation of RVSP by methods A and C were comparable, whereas method B significantly overestimated the actual values.(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of exercise performance by sharp reduction of blood pressure. A study in patients with uncomplicated hypertension.

We evaluated exercise performance in 14 patients with uncomplicated essential hypertension 1 h after the administration of a single dose of placebo, nifedipine (20 mg), captopril (50 mg), and propranolol (80 mg). Drugs were administered at the same time of day following a randomized, double-blind protocol. Mean resting blood pressure (+/- SE) was 135 +/- 3 mm Hg with placebo administration, 118 +/- 4 with captopril, 110 +/- 4 with nifedipine, and 115 +/- 5 with propranolol and increased with exercise to 163 +/- 4, 146 +/- 3, 136 +/- 4, 136 +/- 4, respectively. Oxygen consumption at peak exercise and at ventilatory anaerobic threshold (VAT) was 25.2 +/- 1.1 and 18.1 +/- 1.0 ml/min/kg with placebo. Only propranolol (-2.3 ml/min/kg) decreased peak exercise oxygen consumption. Oxygen consumption at VAT was reduced by nifedipine and propranolol but unaffected by captopril. The effects on exercise capacity of blood pressure reduction in hypertensive patients are dependent on the drug utilized and are not related to the amount of blood pressure reduction. The lowered oxygen consumption at VAT observed with nifedipine and propranolol, and not with captopril, might be due to an excessive downward shift of the muscle perfusion pressure--oxygen consumption relationship which might take place during exercise.