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Biomedical subjects

T Bombardini

Publications and source records attributed to T Bombardini.

At least 19 recordsLinked to original sources
PubMed2002

PEA I and PEA II based implantable haemodynamic monitor: pre clinical studies in sheep.

AIMS: The aims of this study were first, to demonstrate that Peak Endocardial Acceleration during isovolumic systole (PEA I) is related to positive peak LVdP/dt, while Peak Endocardial Acceleration during isovolumic relaxation time (PEA II) is related to aortic diastolic pressure (ADP) and to negative peak LVdP/dt; and second, to test if the simultaneous recording of PEA I and PEA II offers a new chance to monitor indexes of LV systolic and diastolic function. METHODS: An implantable haemodynamic monitor, based on PEA I and PEA II measurements via a microaccelerometer sensor located in the tip of a pacing lead, screwed into the right ventricle, was tested in nine sheep at baseline and during acute haemodynamic interventions: nitrate (0.1 mg/ kg), metaraminol (0.15 mg/kg), dobutamine (5 microg/kg) infusion. ADP, positive and negative peak LVdP/dt were simultaneously recorded by an aortic and left ventricular Millar catheter. RESULTS: PEA I changes were significantly related to positive peak LVdP/dt changes during dobutamine induced inotropic changes (r = 0.83, P < 0.001). PEA II changes were significantly related to both ADP (r = 0.91, P < 0.001) and negative peak LVdP/dt changes (r = 0.92, P < 0.001) during nitrate induced hypotension and metaraminol induced hypertension. CONCLUSION: The simultaneous recording of PEA I and PEA II with an implantable system offers a new chance to monitor indexes of LV systolic and diastolic function.

Animals↗
PubMed2001

Operator independent left ventricular function monitoring during pharmacological stress echo with the new peak transcutaneous acceleration signal.

BACKGROUND: As the myocardium contracts isometrically, it generates vibrations that can be measured with an accelerometer. The vibration peak, peak endocardial acceleration (PEA), is an index of contractility. OBJECTIVE: To evaluate the feasibility of PEA measured by the cutaneous precordial application of the accelerometer sensor; and to assess the usefulness of PEA monitoring during pharmacological stress echocardiography. DESIGN: Feasibility study. SETTING: Stress echo laboratory. PATIENTS: 34 consecutive patients underwent pharmacological stress (26 with dipyridamole; 8 with dobutamine) and PEA monitoring simultaneously. INTERVENTIONS: A microaccelerometer was positioned in the precordial region and PEA was recorded. Dipyridamole was infused up to 0.84 mg/kg in 10 minutes, and dobutamine up to 40 microg/kg/min in 15 minutes. RESULTS: A consistent PEA signal was obtained in all patients. Overall mean (SD) baseline PEA was 0.26 (0.15) g (g = 9.8 m/s(2)), increasing to 0.5 (0.36) g at peak stress (+0.24 g, 95% confidence interval (CI) 0.14 to 0.34 g; p < 0.01). PEA increased from 0.26 (0.16) to 0.37 (0.25) g in the dipyridamole group (+0.11 g, 95% CI 0.08 to 0.16 g; p < 0.01), and from 0.29 (0.1) to 0.93 (0.37) g in the dobutamine group (+0.64 g, 95% CI 0.37 to 0.91 g; p < 0.01). CONCLUSIONS: Using precordial leads this method offers potential for diagnostic application in the short term monitoring of myocardial function. PEA monitoring is feasible during pharmacological stress and documents left ventricular inotropic response quantitatively in a non-invasive and operator independent fashion.

Acceleration↗
PubMed2000

Peak endocardial acceleration reflects heart contractility also in atrial fibrillation.

Previous studies demonstrated that peak endocardial acceleration (PEA) in sinus rhythm is related to LV dP/dtmax. Until now, PEA was never evaluated during R-R interval variations in AF. The aim of this study was to establish the behavior of PEA in AF and the relationship of PEA versus LV dP/dtmax. Six sheep (65 +/- 6 kg) were instrumented with a LV Millar catheter and with an accelerometer lead. AF was induced and PEA, LV dP/dtmax, and ECG were monitored. AF persisted for 5 +/- 1.3 minutes. From sinus rhythm to AF, the heart rate went from 92 +/- 3 to 130 +/- 35 beats/min (P < 0.05), LV dP/dtmax from 684 +/- 18 to 956 +/- 344 mmHg/s (P = NS) and PEA from 0.82 +/- 0.06 to 0.94 +/- 0.33 g (P = NS). The correlation between PEA and LV dP/dtmax was significative in sinus rhythm (r = 0.7, P < 0.05) and in AF (r = 0.8, P < 0.05). A positive relationship was found between the preceding interval and PEA (r = 0.4 +/- 0.07, P < 0.05) and LV dP/dtmax (r = 0.61 +/- 0.08, P < 0.05), while a negative one was found between the prepreceding interval and both PEA (r = -0.39 +/- 0.11, P < 0.05) and LV dP/dtmax (r = -0.64 +/- 0.05, P < 0.05). At the onset of AF, LV dP/dtmax and PEA showed similar changes: beat-to-beat correlation between PEA and LV dP/dtmax was high. As for LV dP/dtmax, PEA is positively related to the preceding interval and negatively related to the prepreceding interval. These data confirm that PEA reflects heart contractility also during AF and hold promise for the use of this sensor in therapeutic implantable devices.

Animals↗
PubMed1997

Autotransfusion in major orthopaedic surgery: experience with 1785 patients.

Using a prospective audit, we have evaluated the efficacy of an integrated autotransfusion regimen which comprised predepositing and intra- and postoperative blood salvage in major orthopaedic surgery. We examined prospectively the records of 1785 patients (1198 females, 5867 males, mean age 62 (range 16-90) yr, preoperative haemoglobin concentration 13.4 (SD 1.4) g dl-1) undergoing total hip arthroplasty (THA, 1229 patients), THA after removal of internal fixation devices (RFD + THA, 18 patients), total knee arthroplasty (TKA, 263 patients), revision surgery of the hip (HR cup + stem revision, 197 patients; cup revision, 53 patients; stem revision, 16 patients) and total knee revision (TKR, nine patients). We estimated that the number of predonations (MSBOS = maximum surgery blood order schedule) was 2 u. for THA, TKA and TKR, and 3 u. for partial or total hip revision and total hip arthroplasty with fixation removal. We found that it was possible to obtain the MSBOS in 1597 patients (89.5%). Homologous red blood cell (HRBC) transfusions were carried out in 131 patients (7.3%). We found that the need to use HRBC was significantly associated with failure to meet the number of MSBOS, female sex, lower preoperative haemoglobin concentration, use of calcium heparin for antithrombosis prophylaxis, more extensive surgery, higher ASA rating and co-existing diseases such as coronary artery disease.

Adolescent↗
PubMed1997

The coronary angiogenetic effect of heparin: experimental basis and clinical evidence.

Heparin is a highly sulfated polysaccharide consisting of a repeating disaccharide structure as found in other glycosaminoglycanes. The intravenous and subcutaneous formulation of the drug is routinely used for its well-known, time-honored antithrombotic effect. However, available evidences linking heparin to angiogenesis raise the possibility of a therapeutically relevant antiischemic effect of the drug. Molecular biology data show that in a hypoxic milieu heparin could facilitate angiogenesis through interactions with a family of polypeptide growth factor mitogens that stimulate endothelial cell proliferation. Experimental data suggest that heparin can augment collateral circulation when combined with other potentially angiogenetic factors, such as repeated ischemia, coronary occlusion, or physical exercise. Clinical data, although very initial, encompassing a total of only 41 heparin-treated patients with coronary artery disease, suggest that heparin facilitates collateral development stimulated by exercise-induced myocardial ischemia in humans. According to the heparin-collateral hypothesis, the mechanism of action of heparin as an antiischemic medication would be independent of its anticoagulant action. The molecular targets of heparin are Factor Xa and IIa for antithrombotic action, heparin-binding growth factors (including fibroblast growth factor and vascular endothelial growth factor) for angiogenesis. The antithrombotic effect is not linked to a cellular target, whereas the angiogenetic effect directly stimulates endothelial cells. The molecular cofactor required for effect is antithrombin III for antithrombosis, and possibly endogenous adenosine for angiogenesis. The therapeutic effect is achieved within minutes or hours for antithrombosis, and within weeks or months for angiogenesis.

Angina Pectoris↗
PubMed1996

A videodensitometric study of transmural heterogeneity of cyclic echo amplitude variation in human myocardium.

The aims of this study were: (1) to assess whether variations in cyclic echo amplitude might be detected across the human myocardium by videodensitometric analysis of images obtained with epicardial echocardiography; and (2) to explore the possible relation between cyclic gray level variation and left ventricular (LV) hypertrophy and function. Experimental studies show that transmural differences in contractile performance across the normal myocardium are paralleled by differences in the cyclic (diastolic-to-systolic) variation of myocardial echo amplitude. Thirty-three patients (aged 60 +/- 11 years) undergoing cardiac surgery were studied by intraoperative epicardial echocardiography. LV mass index as normal (<110 g/m2 in women, <131 g/m2 in men) in 10 patients and increased in 22. Two-dimensional echocardiographic images were obtained with a 5 MHz transducer and digitized off-line. Videodensitometric analysis was performed at end-diastole and end-systole with regions of interest across the septal and posterior wall. The cyclic variation was more pronounced in the left than in the right septal subendocardium (31% +/- 14% vs 16% +/- 14% <0.01) and higher in the subendocardial than in the subepicardial layer of the posterior wall (30% +/- 21% vs 23 +/- 18%, p <0.01). Cyclic variation of the left septal subendocardium was higher in 11 patients with nonhypertrophic ventricles than in 22 with hypertrophic left ventricles (42% +/- 15% vs 27% +/- 12%; p <0.01). The percent cyclic variation of the left septal subendocardium appeared to be much more tightly related to percent systolic thickening in patients with eccentric LV hypertrophy (r=0.80 p <0.01) than in patients with concentric LV hypertrophy (r=0.27, p=0.9) or normal LV mass (r=0.43, p=0.2). A cyclic gray level variation can be consistently detected in different human myocardial regions and layers. It is more obvious in the subendocardial than in the subepicardial layer, and in nonhypertrophic than hypertrophic ventricles. The cyclic subendocardial variation is tightly related to regional systolic thickening in patients with eccentric LV hypertrophy.

Aged↗
PubMed1996

An implantable intracardiac accelerometer for monitoring myocardial contractility. The Multicenter PEA Study Group.

As the myocardium contracts isometrically, it generates vibrations that are transmitted throughout the heart. These vibrations can be measured with an implantable microaccelerometer located inside the tip of an otherwise conventional unipolar pacing lead. These vibrations are, in their audible component, responsible for the first heart sound. The aim of this study was to evaluate, in man, the clinical feasibility and reliability of intracavity sampling of Peak Endocardial Acceleration (PEA) of the first heart sound vibrations using an implantable tip mounted accelerometer. We used a unidirectional accelerometer located inside the stimulating tip of a standard unipolar pacing lead: the sensor has a frequency response of DC to 1 kHz and a sensitivity of 5 mV/G (G = 9.81 m/s-2). The lead was connected to an external signal amplifier with a frequency range of 0.05-1,000 Hz and to a peak-to-peak detector synchronized with the endocardial R wave scanning the isovolumetric contraction phase. Following standard electrophysiological studies, sensor equipped leads were temporarily inserted in the RV of 15 patients (68 +/- 15 years), with normal regional and global ventricular function, to record PEA at rest, during AAI pacing, during VVI pacing, and during dobutamine infusion (up to 20 micrograms/kg per min). PEA at baseline was 1.1 G +/- 0.5 (heart rate = 75 +/- 14 beats/min) and increased to 1.3 G +/- 0.9 (P = NS vs baseline) during AAI pacing (heart rate = 140 beats/min) and to 1.4 G +/- 0.5 (P = NS vs baseline) during VVI pacing (heart rate = 140 beats/min). Dobutamine infusion increased PEA to 3.7 G +/- 1.1 (P < 0.001 vs baseline), with a heart rate of 121 +/- 13 beats/min. In a subset of three patients, simultaneous hemodynamic RV monitoring was performed to obtain RV dP/dtmax, whose changes during dobutamine and pacing were linearly related to changes in PEA (r = 0.9; P < 0.001). In conclusion, the PEA recording can be consistently and safely obtained with an implantable device. Pharmacological inotropic stimulation, but not pacing induced chronotropic stimulation, increases PEA amplitude, in keeping with experimental studies, suggesting that PEA is an index of myocardial contractility. Acute variations in PEA are closely paralleled by changes in RV dP/dtmax, but are mainly determined by LV events. The clinical applicability of the method using RV endocardial leads and an implantable device offers potential for diagnostic applications in the long-term monitoring of myocardial function in man.

Acceleration↗
PubMed1994

Short-term cardiac adaptation to severe haemodilution: an echocardiographic study in normal and hypertensive subjects.

In order to avoid transfusion risks and optimize blood bank resources, in recent years many blood sparing techniques have been proposed, including severe haemodilution. The aim of this study is to assess the pattern of normal haemodynamic and cardiac adaptation to severe haemodilution in patients undergoing major orthopaedic surgery and refusing blood transfusions for religious reasons (the patients were Jehovah's Witnesses). Two-dimensionally guided M-mode echocardiograms were performed at baseline and 4 days after major orthopaedic surgery in 26 Jehovah's Witnesses (age 61 +/- 11 years), with normal regional and global baseline left ventricular function and no valvular disease. Left ventricular (LV) volumes were estimated by using the Teichholz formula. From the latter, we calculated ejection fraction and stroke volume, cardiac output (stroke volume x heart rate), and total peripheral resistance estimated as mean arterial pressure by cuff sphygmomanometer x 80/cardiac output. On the basis of LV mass (ASE-cube corrected by Devereux), two groups were identified: non-hypertrophic (LV mass index < 110 g.m-2 in women and < 130 g.m-2 in males) and hypertrophic. In the 19 patients without LV hypertrophy, haemoglobin decreased from 13.5 +/- 1.6 (mean +/- standard deviation) g.dl-1 (at baseline) to 8.7 +/- 1.3 post-operation (P < 0.01), and peripheral vascular resistances fell from 2131 +/- 450 to 1278 +/- 310 (dyne.s.cm-5) (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Christianity↗
PubMed1994

New bileaflet bioprosthesis: early and mid term results.

A new bovine pericardial bioprosthesis (AMB bioprosthesis) with a bileaflet geometry was designed and developed, with the aim of achieving uniform stress distribution within the prosthesis. The ultimate goal was to limit tissue degeneration to a minimum by attaining optimum fluid dynamics, thereby obtaining an extended clinical durability. The two-leaflet, dome-shaped geometry with a central hinge allowed a very low profile, low ventricular projection in the mitral position, large effective orifice area and low gradients. The design of the thin Delrin stent and the centrally crossing bridge was developed using finite element analysis. Pre-clinical laboratory investigations showed very low trans-valvular gradients and no mechanical or tissue failure after 400 million cycle accelerated wear test. The final model of the prosthesis was manufactured by Baxter-Edwards CVS Division and tested in sheep with good results for up to five months. A limited clinical trial was started in January 1990 and stopped one year later encompassing 12 aortic and six mitral implants. The patients were followed clinically and by echocardiography three, six and 12 months, and four years after surgery. Mean gradients were 4 mmHg in the mitral and 10 mmHg in the aortic position with only minimum regurgitation and no tissue failure. We conclude that early and mid term results with this new pericardial bioprosthesis appear to be favorable and intend to closely monitor further outcome within the limited patient population.

Animals↗
PubMed1990

[Mexiletine in patients with progressive infarction and reduced ventricular function: anti-arrhythmic efficacy and hemodynamic effects].

Reduced left ventricular function and ventricular arrhythmias are the main risk factors associated with sudden death in patients with previous acute myocardial infarction. Antiarrhythmic therapy may have side-effects on myocardial contractility and sometimes makes the arrhythmia itself worse, especially when the pump function is seriously compromised. The aim of this study was to evaluate the efficacy of oral mexiletine as well as any modifications in left ventricular function by means of ambulatory ECG monitoring and angiocardiography with Tc 99m, at rest and after the handgrip test, in 20 patients with previous myocardial infarction and ventricular arrhythmias who were grouped into NYHA class II and class III. The mexiletine therapy lasted three weeks. Both classes showed a significant decrease in the number of ventricular extrasystoles/hour and in the number of couples (p less than 0.01). The decrease in the number of the ventricular runs proved to be higher in the general analysis (p less than 0.01) than in each NYHA class (p less than 0.05). At the end of the study, significant modifications were not observed either in the end-diastolic and end-systolic volumes, or in the ventricular ejection fraction.

Aged↗
PubMed1989

[Clinical indications for performing Doppler ultrasonography of the extracranial carotid vessels. A series of 805 subjects].

Duplex scanning of the extracranial carotid vessels is a highly reliable medical investigation for identifying atherosclerotic or other pathology in this vascular region. The introduction of this technique into hospital practice has posed the problem of when it is indicated. The present study has shown that almost half the examinations carried out (45.2%) were requested on the basis of what were defined as "general" symptoms (vertigo, lipothymia, migraine, etc.); this group showed a low prevalence of atheromatous plaques. 22.7% of the examinations were requested as a control in the presence of atherosclerosis in another vascular region (coronaries, arteries of the lower extremities, etc.) and in these patients the prevalence of carotid stenosis was high or very high. Patients examined subsequently to a neurological episode came to 15.3% of the total. There was a high prevalence of carotid atheromatous lesions. Numerous controls were requested in subjects with type 2A and 2B hyperlipoproteinaemia (6.7% of the total) with a prevalence of atheromatous lesions higher than the homogeneous-for-age group. A limited number of patients (2%) underwent the study following visual disturbances of presumable ischaemic origin. The prevalence of carotid stenoses in these subjects is high. Patients who underwent carotid TEA (8.1%) represent a special group in whom intervention brings a general improvement although the percentage of vessel restenosis exceeds 20%.

Aged↗
PubMedDate not supplied

Pulsed venous flow pattern with hemodilution.

Venous flow pattern changes and venous flow were assessed in relation to the degree of hemodilution. Femoral vein flow was measured with a duplex scanner in two groups of 11 patients 20 days and 5 days preoperatively, and 1 day postoperatively. In group I, hemodilution was used and patients gave three autologous blood predonations between day 20 and day 5. Perioperative blood loss was reintegrated by electrolyte solution. In group II, hemodilution was not used and autologous blood predonations were not carried out. These patients received a perioperative homologous blood transfusion of 800 mL. Hemoglobin was lower on day 5 (11.3 +/-1.4 vs 13.1 +/-1 g/dL, p<0.05) and on postoperative day 1 (8.9 +/-1.6 vs 10.6 +/-1, p<0.05) in group I. The decrease in hemoglobin was associated with an increase in blood flow and a pulsed venous flow pattern in 14 of 22 veins after autologous blood predonation and in 21 of 22 veins on postoperative day 1 (p<0.05). Increased venous flow in hemodilution is associated with a pulsed venous flow pattern.

Aged↗
PubMedDate not supplied

Surgical approach to combined carotids and coronaries lesions.

A preoperative carotid evaluation by a Duplex Scanner ATL Mark V has been carried out in 338 patients candidates to CABG. When a critical lesion was detected a digital angiography was subsequently performed. In 19 patients an operation was done because the coexistence of lesions in the carotids and the coronaries. The indications, the timing of the operations and the surgical approach are discussed. In the Author's minds the combined procedure seems to be advisable.

Carotid Artery Diseases↗