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Biomedical subjects

M Pepi

Publications and source records attributed to M Pepi.

At least 55 records · Page 3Linked to original sources
PubMed1995

How the two sides of the heart adapt to graded impedance to venous return with head-up tilting.

OBJECTIVES: The study sought to probe whether the adaptation of the right ventricle to reduced preload may influence that of the left ventricle (interdependence) and whether and how this mechanism contributes to maintain an adequate pump function. BACKGROUND: A study like this requires that subjects be normal, restraint of venous return be gradual, systolic function and diastolic filling and dimensions of either ventricle be monitored. METHODS: Of 30 healthy men (mean [+/- SD] age 35 +/- 7 years) studied with Doppler echocardiography, 20 were studied in the supine position and after 20 degrees, 40 degrees and 60 degrees tilting for 10 min; the remaining 10 subjects were also studied at the same levels of tilting for 45 min. RESULTS: At 20 degrees, heart rate, blood pressure and stroke volume were steady; the diastolic right ventricular area was reduced (p < 0.001); and the end-diastolic dimension of the left ventricle did not vary. Tilting at 40 degrees and 60 degrees increased heart rate and diastolic pressure, decreased systolic pressure and stroke volume and reduced the diastolic dimensions of both ventricles. At any tilting level, right and left peak early inflow velocities (E) were decreased, peak late velocities (A) were unchanged, and E/A ratios were reduced, suggesting that the atrial-ventricular pressure difference was diminished bilaterally and that the atrial contribution to ventricular filling was maintained. Tachycardia at 40 degrees and 60 degrees tilting was not associated with enhancement of left ventricular fiber fractional shortening or mean velocity of shortening for any corresponding end-systolic wall stress; changes in heart rate also did not correlate with those in fiber fractional shortening and velocity of shortening. The adaptive responses to the same degrees of tilting for a duration of 45 min were comparable to those at 10 min. CONCLUSIONS: With moderate restraint of venous return, the left ventricle maintains filling and output in response to a reduction in right ventricular diastolic volume, which increases left ventricular compliance (interdependence), and to the pulmonary blood reservoir, which compensates for an immediate decrease in right ventricular stroke volume. The decreased lung blood volume would facilitate right ventricular ejection, resulting in a normal stroke output despite the reduced preload. Thus, mechanical adjustments fully compensate for moderate reduction of venous return. A more severe reduction requires chronotropic support for the maintenance of cardiac output. With prolongation of tilting time to 45 min, adaptive mechanisms do not become exhausted in normal persons.

Adaptation, Physiological↗
PubMed1995

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.

Adult↗
PubMed1994

Obstruction of the right pulmonary artery by an aortic aneurysm complicating previous coronary bypass grafting.

We report a case of right main pulmonary artery compression due to a type II dissecting aortic aneurysm simulating massive pulmonary artery embolism. Aortic tear and intimal splitting developed around an aortocoronary bypass graft performed 11 months earlier. Ultrasound detected the aortic aneurysm and pulmonary hypertension, and excluded emboli in the pulmonary artery. Pulmonary angiography explained the lung involvement, showing compression of the right main pulmonary artery. Coronary and aortic angiograms demonstrated that the aortic aneurysm developed around the right venous bypass graft. Surgery confirmed the angiographic findings and the pathogenesis of the syndrome.

Aortic Dissection↗
PubMed1994

Anomalous origin of the left anterior descending and circumflex coronary arteries by two separate ostia from the right sinus of Valsalva.

We report a case of absence of the left main coronary artery with the left anterior descending and circumflex coronary arteries arising by two separate ostia from the right sinus of Valsalva in a patient without other congenital cardiovascular malformations. The clinical and angiographic features of this exceedingly rare anomaly are described with a brief review of previously documented cases.

Coronary Vessel Anomalies↗
PubMed1994

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.

Adolescent↗
PubMed1994

[Multiplane transesophageal echocardiography for the monitoring of cardiac surgery].

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)

Adolescent↗
PubMed1994

[Transesophageal coronary flowmetry and ventricular diastolic properties in surgically treated aortic insufficiency].

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.

Aortic Valve↗
PubMed1993

Control of pulmonary vasomotility in congestive heart failure.

Although enhanced sympathetic tone is a well-known component of the autonomic imbalance of heart failure, its influence on pulmonary vasomotility is undefined. We investigated the pulmonary circulation in 12 patients with congestive heart failure in NYHA functional class III and in a control group of 10 normal subjects. Sympathetic influence on pulmonary vessels was studied through adrenergic activation by the arithmetic test and the cold pressor test. A rubber balloon was distended in the inferior vena cava to reduce transpulmonary flow and its influence on vascular tone. In normal individuals the arithmetic test caused pulmonary vasodilation, probably because of the mechanical effect of a largely enhanced flow: in fact, caval obstruction unmasked a neurogenic vasoconstrictor response to the arithmetic test by simply reducing the amount of cardiac output increase. In patients with heart failure, cardiac output and pulmonary arteriolar resistance remained steady during the arithmetic test, no matter what the condition of the venous return was. The cold pressor test was always a vasoconstrictor stimulus, but only in normal subjects was vasoconstriction potentiated by reducing, with caval obstruction, transpulmonary flow and its vasodilatory influence. From these data an attenuation of the sympathetic influence on pulmonary vessels in congestive heart failure seems to be likely. This might be explained as the result of modifications of pulmonary vessels rather than of reduced sympathetic excitability since circulating catecholamine levels varied to similar extents in the two groups during the tests. In congestive heart failure interstitial edema and vascular wall imbibition might increase pulmonary vessel tone and decrease vascular receptor availability. Lower reactivity to sympathetic stimuli, particularly to the vasoconstrictor ones, would ensue.

Adult↗
PubMed1993

Isolated ultrafiltration in moderate congestive heart failure.

OBJECTIVES: The aim of this study was to evaluate whether ultrafiltration is beneficial in patients with moderate congestive heart failure. BACKGROUND: Ultrafiltration is beneficial in patients with severe congestive heart failure. METHODS: We studied 36 patients in New York Heart Association functional classes II and III in stable clinical condition. Eighteen patients (group A) were randomly selected and underwent a single session of ultrafiltration (venovenous bypass, mean [+/- SEM] ultrafiltrate 1,880 +/- 174 ml, approximately 600 ml/h) and 18 (group B) served as control subjects. RESULTS: Two patients in group A and three in group B did not complete the 6-month follow-up study. In group A, soon after ultrafiltration there were significant reductions in right atrial pressure (from 8 +/- 1 to 3.4 +/- 0.7 mm Hg, pulmonary wedge pressure (from 18 +/- 2.5 to 10 +/- 1.9 mm Hg) and cardiac index (from 2.8 +/- 0.2 to 2.3 +/- 0.2 liters/min). During the follow-up period, lung function improved, extravascular lung water (X-ray score) decreased and peak oxygen consumption (ml/min per kg) increased significantly from 15.5 +/- 1 (day -1) to 17.6 +/- 0.9 (day 4), to 17.8 +/- 0.9 (day 30), to 18.9 +/- 1 (day 90) and to 19.1 +/- 1 (day 180). Oxygen consumption at anaerobic threshold (ml/min per kg) also increased significantly from 11.6 +/- 0.8 (day -1) to 13 +/- 0.7 (day 4), to 13.7 +/- 0.5 (day 30), to 15.5 +/- 0.8 (day 90) and to 15.2 +/- 0.8 (day 180). These changes were associated with increased ventilation, tidal volume and dead space/tidal volume ratio at peak exercise. The improvement in exercise performance was associated with a decrease in norepinephrine at rest, a downward shift of norepinephrine kinetics at submaximal exercise and an increase in norepinephrine during orthostatic tilt. None of these changes were recorded in group B. CONCLUSIONS: In patients with moderate congestive heart failure, ultrafiltration reduces the severity of the syndrome.

Aged↗
PubMed1993

Percutaneous pericardiocentesis versus subxiphoid pericardiotomy in cardiac tamponade due to postoperative pericardial effusion.

In a retrospective study, 42 patients with acute cardiac tamponade due to pericardial effusion were evaluated following cardiac surgery, and the pericardial fluid was drained by one of two alternative methods: two-dimensional echocardiographic-guided pericardiocentesis (2D-echo) or subxiphoid surgical pericardiotomy. During the first period (from 1982 to 1986), one of the two methods was chosen by the treating physicians, whereas in the second period (from 1986 to 1991), 2D-echo-guided pericardiocentesis was the treatment of choice. Percutaneous pericardiocentesis was performed using local anesthesia in 29 patients. A Tuohy needle was inserted at the left xipho-costal junction and, when fluid was obtained, 6 mL of saline solution was injected during 2D-echo contrast monitoring, and a multiple-hole, 6F, 30-cm catheter was inserted by means of a guidewire and positioned into the posterior pericardium, as near as possible to the atrioventricular groove. Complete drainage of pericardial fluid by percutaneous pericardiocentesis was obtained in 26 patients (89%). This procedure also allowed the evacuation of posterior and loculated effusions. Complications included two right ventricular punctures, which were immediately recognized by 2D-echo contrast and produced no serious consequences. Sixteen patients who underwent surgical pericardiotomy had complete evacuation of pericardial fluid without major complications (two of them suffered atrial arrhythmias during the procedure). The average amount of fluid drained, as well as the localization of the effusions, were the same for both groups. 2D-echo-guided pericardiocentesis was found to be a useful, safe, and simple technique. It can be used as an alternative treatment to subxiphoid pericardiotomy for cardiac tamponade due to postoperative pericardial effusions.

Adult↗
PubMed1993

Methylmercury Resistance in Desulfovibrio desulfuricans Strains in Relation to Methylmercury Degradation.

Two strains of Desulfovibrio desulfuricans, one known to synthesize monomethylmercury from ionic mercury, were grown to determine methylmercury toxicity and for comparison with an anaerobic strain of Clostridium pasteurianum, a H(2) producer, and with the broad-spectrum mercury-resistant Pseudomonas putida strain FB-1, capable of degrading 1 mug of methylmercury to methane and elemental mercury in 2 h. The CH(3)HgCl resistance of D. desulfuricans strains was 10 times that of P. putida FB-1 and 100 times that of C. pasteurianum. The methylmercury resistance of D. desulfuricans was related to the disappearance of methylmercury from cultures by transformation to dimethylmercury, metacinnabar, methane, and traces of ionic mercury. During a 15-day experiment the kinetics of the two volatile compounds dimethylmercury [(CH(3))(2)Hg] and methane were monitored in the liquid by a specific new technique with purge-and-trap gas chromatography in line with Fourier transform infrared spectroscopy and in the headspace by gas chromatography with flame ionization detection. Insoluble metacinnabar (cubic HgS) of biological origin was detected by X-ray diffractometry in the gray precipitate from the insoluble residue of the pellet of a 1-liter culture spiked with 100 mg of CH(3)HgCl. This was compared with a 1-liter culture of D. desulfuricans LS spiked with 100 mg of HgCl(2). In a further experiment, it was demonstrated that insoluble, decomposable, white dimethylmercury sulfide [(CH(3)Hg)(2)S] formed instantly in the reaction of methylmercury with hydrogen sulfide. This organomercurial was extracted with chloroform and identified by gas chromatography in line with mass spectrometry. The D. desulfuricans strains were resistant to high concentrations of methylmercury because they produced insoluble dimethylmercury sulfide, which slowly decomposed under anaerobic conditions to metacinnabar and volatilized to dimethylmercury and methane between pHs 6.2 and 6.5 for high (4.5-g . liter) or low (0.09-g . liter) sulfate contents. Methane was produced from CH(3)HgCl at a lower rate than by the broad-spectrum Hg-resistant P. putida strain FB-1.

Journal Article↗
PubMed1993

Sustained cardiac diastolic changes elicited by ultrafiltration in patients with moderate congestive heart failure: pathophysiological correlates.

OBJECTIVE: To investigate the pathophysiological (cardiac function and physical performance) significance of clinically silent interstitial lung water accumulation in patients with moderate heart failure; to use isolated ultrafiltration as a means of extravascular fluid reabsorption. DESIGN: Echocardiographic, Doppler, chest x-ray evaluations, and cardiopulmonary tests at baseline, soon after ultrafiltration (veno venous extracorporeal circuit), and four days, one month, and three months later. SETTING: University institute of cardiology. SUBJECTS: 24 patients with heart failure due to idiopathic dilated cardiomyopathy or ischaemic myocardial disease with sinus rhythm and ejection fraction less than 35%. Twelve were randomised to ultrafiltration and 12 were taken as controls. MAIN OUTCOME MEASURES: Left ventricular systolic function (from ultrasonography); Doppler evaluation of mitral, tricuspid, and aortic flow and echo-Doppler determination of cardiac output; radiological score of extravascular lung water; right and left ventricular filling pressures; oxygen consumption at peak exercise and exercise tolerance time in cardiopulmonary tests. RESULTS: Soon after ultrafiltration (1976 (760) ml of fluid removed) the following was observed: a reduction in radiological score of extravascular lung water (from 15(1) to 9(1)) and of right (from 7.1 (2.3) to 2.3 (1.7) mm Hg) and left (from 17.6 (8.8) to 9.5 (6.4) mm Hg) ventricular filling pressures; an increase in oxygen consumption at peak exercise (from 15.8 (3.3) to 17.6 (2) ml/min/kg) and of tolerance time (from 444 (138) to 508 (134) s); a slight decrease in atrial and ventricular dimensions; no changes in the systolic function of the left ventricle; a reduction of the early to late filling ratio in both ventricles (mitral valve from 2 (2) to 1.1 (1.1)); (tricuspid valve from 1.3 (1.3) to 0.69 (0.18)) and an increase in the deceleration time of mitral and tricuspid flow, reflecting a redistribution of filling to late diastole. Variations in the ventricular filling pattern, lung water content, and functional performance persisted for three months in all cases. None of these changes was detected in the control group. CONCLUSIONS: Reduction of interstitial lung water was probably the mechanism whereby ultrafiltration modified the pattern of filling of the two ventricles and improved functional performance.

Aged↗
PubMed1993

[Changes in the physical characteristics of the lung can account for the improvement observed after ultrafiltration in patients with moderate heart failure].

Ultrafiltration improves the clinical condition of patients with moderate congestive heart failure. Ultrafiltration (1895 +/- 120 ml of plasma water, rate 600 ml/h, veno-venous bypass) was performed in 30 patients with moderate congestive heart failure in stable clinical conditions. The effects of ultrafiltration were assessed through pulmonary function and cardiopulmonary exercise tests performed before and 30 days after the procedure. Vital capacity, forced expiratory volume (1 s) and maximal voluntary ventilation improved as improved exercise performance (increase in oxygen consumption at peak exercise and at anaerobic threshold). Tidal volume at anaerobic threshold and at peak exercise increased by 10% with no changes in respiratory rate. This suggests that ultrafiltration induces changes at the physical characteristics of the lungs probably related to changes in lung water content.

Aged↗