Search PubMed⌕ Search

Biomedical subjects

C Montemartini

Publications and source records attributed to C Montemartini.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Percutaneous approach in the use of subclavian vein in pacemaker implantation].

BACKGROUND AND METHODS: We analyzed the complications of 1729 pacemakers implants (from October 1980 to December 1992) divided according to the way of leads insertion. The approaches from the subclavian vein was used in 1220 cases, the cephalic vein was used in 431 implants and the external jugular vein in 78. RESULTS: Major complications were: pocket bleeding (108 cases), pocket erosion (15 cases), infection (2 cases), lead fracture (5 cases), lead dislodgement (20 cases), pneumothorax (4 cases, only for subclavian puncture). There were no significative differences in the complications between the three approaches. On the other hand, the subclavian puncture reduces the time of the procedure, is less traumatic and allows to insert and to position several leads. CONCLUSIONS: We suggest to use the subclavian vein approach as first choice to implant one or more leads, being this way safe and fast.

Evaluation Studies as Topic↗
PubMed1994

[Coronary vasomotor response to acetylcholine correlates with plasma levels of cyclosporin and triglycerides in patients with heart transplantation].

BACKGROUND: Vasoconstriction of normal coronary arteries has been reported after intracoronary (i.c.) administration of acetylcholine (Ach) in cardiac transplant patients and has been related to early endothelial disfunction; the clinical correlates of this response are still unknown. METHODS: We infused graded i.c. concentrations of Ach in 32 pts with angiographically smooth coronary arteries 1 to 3 years after heart transplantation. Changes in diameters of the proximal and middle segments of the left anterior descending coronary artery were measured by quantitative coronary angiography (automatic edge detection). RESULTS: The response to Ach ranged from +44% to -58%; at linear regression analysis it was significantly related to the plasma levels of cyclosporine (r = -0.39, p < .05) and triglycerides (r = -0.42, p < .02) but not to vessel diameter, recipient and donor age, time after transplantation, hypertension, cholesterol levels, number of acute rejection episodes and previous cytomegalovirus infections. CONCLUSIONS: In heart transplant pts with angiographically normal coronary arteries i.c. Ach may reveal endothelial disfunction which is associated with high cyclosporine and triglycerides plasma levels. Whether this response may predict an earlier development of coronary disease remains to be elucidated.

Acetylcholine↗
PubMed1993

Assessment of left ventricular function by isometric handgrip exercise after thrombolysis in patients with refractory unstable angina.

The handgrip test has been proposed for the evaluation of the hemodynamic reserve in patients with coronary artery disease and to quantitate the impairment of left ventricular (LV) function. The present study was designed to evaluate the effect of thrombolytic therapy in patients with refractory unstable angina in order to test the hypothesis that a reduction in intracoronary thrombosis could ameliorate their hemodynamic response to the handgrip test. During left heart catheterization, 20 patients with refractory unstable angina of recent onset performed a handgrip test before (HG1) and 24-72 hours after (HG2) being randomized to receive recombinant tissue-type plasminogen activator or placebo, according to a double-blind parallel group design. HG1 induced an increase in heart rate (p < 0.001), in systolic pressure (p < 0.001), and a reduction in ejection fraction (p < 0.05). Changes in LV end-diastolic pressure during baseline handgrip were highly different in individual patients, resulting in a trend toward an increase. Similarly, a different individual response was observed in the behavior of the isovolumetric and relaxation indices. In comparison with HG1, no difference was detected during HG2 in the 2 treatment groups with respect to changes in LV volumes, ejection fraction, LV systolic and diastolic pressures, +dP/dt, (dP/dt)/P, -dP/dt, and tau index. In patients with refractory unstable angina of recent onset, the handgrip test performed before and after thrombolysis did not prove to be useful in assessing directional changes of LV performance, mainly because of the different individual response to the baseline handgrip test.

Angina, Unstable↗
PubMed1993

Beta-endorphins during coronary angioplasty in patients with silent or symptomatic myocardial ischemia.

OBJECTIVES: The aims of this study were to correlate beta-endorphin plasma levels and anginal pain in patients with ischemia induced by percutaneous transluminal coronary angioplasty and to detect eventual endorphin variations during balloon occlusion. BACKGROUND: The opioid system appears involved in the absence of pain occurring in silent myocardial ischemia. METHODS: Beta-endorphin plasma levels were measured 24 h before, just before, during and after coronary angioplasty (performed on the left anterior descending artery) in 53 men with documented coronary artery disease and exercise-induced myocardial ischemia. RESULTS: Group 1 (33 patients) reported symptoms; group 2 (20 patients) was asymptomatic during angioplasty. In these patients, the prevalence of exercise-induced silent ischemia was 57%. The occurrence of angina during exercise or angioplasty was related to the frequency of angina during daily life when patients were subgrouped. The severity and distribution of coronary artery disease did not differ between the two groups. During angioplasty, the number of balloon inflations and the inflation time and pressure were similar in symptomatic and asymptomatic patients. In each group, no short-term variability of baseline beta-endorphin plasma levels was observed during 2 consecutive days. Corresponding beta-endorphin plasma levels (at baseline and during and after angioplasty) were significantly higher in Group 2. During balloon occlusion, the levels decreased significantly in the symptomatic group at the onset of angina but remained stable in the asymptomatic group. CONCLUSIONS: Methodologic variables and the severity of coronary artery disease did not influence the presence of symptoms during angioplasty-induced ischemia. Beta-endorphin plasma levels were higher and more stable in patients with silent ischemia during angioplasty, suggesting that opiate levels and their variation during ischemia are associated with individual attitude toward anginal pain.

Adult↗
PubMed1993

Influence of elastic recoil on restenosis after successful coronary angioplasty in unstable angina pectoris.

The elastic behavior of the dilated coronary vessel has been reported to affect the immediate results of coronary angioplasty. To determine whether elastic recoil may also influence the long-term restenosis process, 98 consecutive patients with unstable angina and 1-vessel disease were studied. An automated coronary quantitative program was used for the assessment of balloon and coronary luminal diameters. Elastic recoil was defined as the percent reduction between minimal balloon diameter at the highest inflation pressure and minimal lesion diameter immediately after coronary angioplasty. Follow-up coronary arteriography was performed 8 to 12 months after the procedure in all patients. The mean elastic recoil averaged 17.7 +/- 16% and was correlated to the degree of residual stenosis immediately after coronary angioplasty (r = 0.64; p < 0.001). Restenosis, defined as > 50% diameter stenosis at follow-up, developed in 53 patients (54%). There was no correlation between the degree of elastic recoil and the changes in minimal lesion diameter observed during follow-up, whereas a positive correlation between the amount of elastic recoil and the incidence of restenosis was documented (r = 0.84; p < 0.05). Thus, the elastic properties of the dilated vessel do not influence the active process of restenosis. However, because elastic recoil negatively influences the initial results of angioplasty, it is more likely that further reductions in lumen diameter during follow-up can reach a threshold of obstruction considered critical for a binary definition of restenosis.

Adult↗
PubMed1993

[The remodelling of the heart in heart failure: from thoracic radiography to magnetic resonance].

Congestive heart failure represents the most common medical hospital discharge diagnosis, and can occur in patients with preserved indexes of left ventricular systolic function, even in absence of patent coronary or valvular heart disease. The present review examines the role of imaging techniques in the diagnosis and follow-up of these patients. Imaging of the heart has undergone dramatic advances with the development and refinement of new imaging modalities such as echocardiography, computed tomography, magnetic resonance and radionuclide emission tomography. The role of "low-tech" modalities such as chest roentgenogram is discussed. The possibilities offered by ultrasounds or magnetic resonance in tissue characterization are then compared with the actual capability of cardiac imaging in detecting myocardial tissue alterations (oedema, ischemia, myocarditis, etc.) and/or degeneration (fatty degeneration, fibrosis, amyloidosis, etc.). Finally, the potential use in modern clinical medicine of magnetic resonance spectroscopy and positron emission tomography to study myocardial metabolism and cellular function are discussed.

Angiocardiography↗
PubMed1992

Right ventricular failure after heart transplantation: relationship with preoperative haemodynamic parameters.

The prevalence of right ventricular failure after orthotopic heart transplantation, evaluated in 196 patients, was 11.7%, as assessed by the presence during the first postoperative month of right atrial pressure > 10 mm Hg. Two deaths, related to refractory right ventricular failure, were observed within the first month, both in subjects with preoperative pulmonary arteriolar resistances > 5 Wood Units. The haemodynamic profile after heart transplantation showed a significant decrease (P < 0.01) and an early normalization of pulmonary arterial pressure, pulmonary wedge pressure and pulmonary arteriolar resistances, while right atrial pressure slowly decreased until the third month. In a long-term analysis of survival (death within 1 year) the probability of death was significantly related to the values of right atrial pressure and cardiac index during the first month after heart transplantation. Otherwise, the presence of elevated values of right atrial pressure did not show a significant correlation with the echocardiographic right ventricular end-diastolic diameter nor with the presence of right bundle branch block. The careful selection of patients referred for the cardiac transplantation (mean value of pulmonary arteriolar resistances in the evaluated subjects was 2.5 +/- 1.5 Wood Units) improves the probability of avoiding the appearance of severe right ventricular failure in the postoperative period in most cases. The best predictor of right ventricular failure remains to be clearly identified.

Blood Pressure↗
PubMed1992

Different susceptibility to the development of nitroglycerin tolerance in the arterial and venous circulation in humans. Effects of N-acetylcysteine administration.

BACKGROUND: Tolerance to the effects of organic nitrates develops rapidly during continuous exposure to these drugs; its main mechanism seems to be an intracellular sulfhydryl group depletion. However, the relative susceptibility to the development of nitroglycerin tolerance of the arterial or venous circulation in humans is still a matter of dispute. METHODS AND RESULTS: Twenty patients with coronary artery disease underwent a continuous 24-hour nitroglycerin infusion followed by a bolus administration of N-acetylcysteine. Forearm blood flow (ml/100 ml/min) and venous volume (ml/100 ml) were measured by strain gauge plethysmography under control conditions, at the end of nitroglycerin titration, after 24-hour infusion, and after N-acetylcysteine; vascular resistance was calculated as mean cuff blood pressure divided by flow. After 24 hours of nitroglycerin infusion, the initial increase in venous volume was reduced 48% (p less than 0.01), whereas the acute effects on vascular resistance were not attenuated in the whole group. N-Acetylcysteine completely restored nitroglycerin venodilator effects in all 10 patients in whom attenuation of the venous effects was observed during the infusion period. CONCLUSIONS: The data indicate that the susceptibility to the development of nitrate tolerance in humans is higher in the venous than in the arterial circulation, and that the sulfhydryl group donor N-acetylcysteine is extremely effective in reversing nitroglycerin tolerance in the venous circulation in humans.

Acetylcysteine↗
PubMed1992

[Hemodynamic effects of enalapril in patients with non-complicated acute myocardial infarct].

To evaluate the hemodynamic effects of the first oral administration of enalapril maleate, a long-acting ACE-inhibitor, in the early phase of an acute uncomplicated myocardial infarction, we studied 15 patients, in Killip class I or II, within 72 hours from the onset of symptoms. Hemodynamic measurements were obtained by a triple lumen 7 F Swan-Ganz catheter, inserted into the pulmonary artery, under control conditions and 2, 4, 6, 8 and 12 hours after 10 mg (15 patients) and 20 mg (11 patients) of the drug. Ten milligrams of enalapril reduced systolic and mean arterial blood pressure (from 118 +/- 17 to 111 +/- 18 mmHg, p < .05, and from 92 +/- 12 to 83 +/- 12 mmHg, p < .01, respectively), with a maximum effect after 4 hours from administration. Heart rate and vascular resistances showed an insignificant trend toward reduction, and no changes were observed in left ventricular systolic work index, right and left ventricular filling pressures or cardiac index. Hemodynamic changes induced by 20 mg of the drug, in a smaller group of patients, had a similar trend, which did not reach a statistical significance. In conclusion, in patients with acute uncomplicated myocardial infarction, a single oral dose of enalapril maleate is safe and well tolerated, does not induce severe hypotension, and produces potentially beneficial changes in hemodynamics.

Administration, Oral↗
PubMed1992

[Comparison of results of echo-dobutamine and ECG-dobutamine tests in the diagnosis of coronary disease].

The aim of the study was to compare the results of 2D-Echocardiographic (ECHO) vs 12-lead Electrocardiographic (ECG) monitoring during Dobutamine (DOB) infusion performed as a stress test in patients referred for the evaluation of chest pain of suspected ischemic origin. Fourty-seven consecutive patients, 40 m and 7 f, mean age 52 +/- 9 years, were studied after interruption of any antianginal therapy. DOB was infused in 5-minute stages with incremental doses of 5 mcg/kg/min up to a maximal dose of 40 mcg/kg/min. 2D-ECHO monitoring could not be performed in 3 out of 47 patients because of a poor acoustic window. Thus, the overall feasibility was 94% for 2D-ECHO DOB test vs 100% for ECG DOB test (p = ns). The ECG and 2D-ECHO findings were compared in the remaining 44 patients. Criteria for positivity were: transient regional dyssynergy absent or of lesser degree in the baseline examination for 2D-ECHO; ST-segment shift > 0.1 mV from baseline for ECG. The test was stopped when a regional wall motion abnormality developed even in the absence of significant ECG changes. Angiographically assessed coronary artery disease (CAD) was considered significant when a > 50% reduction of the luminal diameter in at least 1 major coronary vessel occurred. There were 10/44 patients with no significant CAD and 34/44 patients with CAD; 16 had single, 18 double or triple and/or left main vessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

A new method for quantitation of mitral regurgitation based on color flow Doppler imaging of flow convergence proximal to regurgitant orifice.

BACKGROUND: Imaging of the flow convergence region (FCR) proximal to a regurgitant orifice has been shown to provide a method for quantifying the regurgitant flow rate. According to the continuity principle, the FCR is constituted by concentric hemispheric isovelocity surfaces centered at the orifice. The flow rate is constant across all isovelocity surfaces and equals the flow rate through the orifice. For any isovelocity surface the flow rate (Q) is given by: Q = 2 pi r2 Vr, where 2 pi r2 is the area of the hemisphere and Vr is the velocity at the radial distance (r) from the orifice. METHODS AND RESULTS: We studied 52 consecutive patients with mitral regurgitation (mean age, 49 years; age range, 21-66 years) verified by left ventricular angiography using color flow mapping. The FCR r was measured as the distance between the first aliasing limit--at a Nyquist limit obtained by zero-shifting the velocity cutoff to 38 cm/sec--and the regurgitant orifice. Seven patients without evidence of an FCR had only grade 1+ mitral regurgitation angiographically. There was a significant relation between the Doppler-derived maximal instantaneous regurgitant flow rate and the angiographic degree of mitral regurgitation in the other patients (rs = 0.91, p less than 0.001). The regurgitant flow rate by Doppler also correlated with the angiographic regurgitant volume (r = 0.93, SEE = 123 ml/sec) in the 15 patients in normal sinus rhythm and without other regurgitant lesions in whom it could be measured. The correlation between regurgitant jet area within the left atrium and the angiographic grade was only fair (rs = 0.75, p less than 0.001). CONCLUSIONS: Color flow Doppler provides new velocity information about the proximal FCR in patients with mitral regurgitation. According to the continuity principle, the maximal instantaneous regurgitant flow rate, obtained with the FCR method, may provide a quantitative estimate of the severity of mitral regurgitation, which is relatively independent of technical factors.

Angiocardiography↗
PubMed1991

[Doppler estimation of the stenotic mitral valve area. Direct application of the continuity equation to the flow convergence region].

The continuity equation, applied to the flow convergence region (FCR), fournishes a simple alternative to calculate stenotic valve area. The flow rate in the FCR can be calculated by multiplying the hemispheric isovelocity surface area by the velocity of the isovelocity surface. Since according to the continuity principle the flow rate through any isovelocity surface equals the flow rate through the stenotic orifice, the stenotic orifice area can be calculated as: 2 pi r2Vr/Vm, where 2 pi r2 is the hemispheric isovelocity area, Vr is the velocity at the radial distance r from the orifice and Vm is the peak jet velocity. This study was designed to analyze the validity of application of the continuity equation to the FCR for estimating mitral orifice area by Dopler ultrasound. We studied 35 consecutive patients with rheumatic mitral stenosis. Three patients were excluded; the final study population consisted of 32 patients (8 men and 24 women; mean age 56 years). Nine patients were in normal sinus rhythm and 23 in atrial fibrillation. Doppler examination was performed from the apical approach within 24 hours of cardiac catheterization. On color Doppler image Vr was defined as the first aliasing limit (lowered to 38 cm/s to increase FCR r); r represented the maximal early diastolic distance between the first alias and the stenotic orifice in a direction parallel to that of the transducer; Vm was the early diastolic peak jet velocity by continuous wave Doppler.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Hemodynamic benefits of sequential atrioventricular pacing].

The purpose of this study was to evaluate the hemodynamic benefits of atrioventricular (A-V) sequential pacing. 30 pts implanted with DDD pacemakers underwent M-mode, B-mode and Doppler echocardiography. In each patient, left ventricular (LV) stroke volume was assessed by measuring the time-velocity integral of mitral inflow in the following modes and rates: VOO at 70 ppm or at the minimum stimulation rate and at 120 ppm; DOO at the same rates with different A-V delay (100, 150, 200, 250 and, whenever possible, 300 msec). The increase in stroke volume obtained with dual chamber pacing at the optimal A-V delay was 45 +/- 25% at 75 ppm and 29 +/- 14% at 120 ppm (p less than 0.05 75 vs 120 ppm). This increase was significantly higher in pts with than in pts without LV hypertrophy (respectively: 51.9 +/- 20.4 vs 36.9 +/- 20.8% at 75 ppm, p less than 0.05 and 33 +/- 13.4 vs 25.4 +/- 14.5% at 120 ppm, p = 0.08). Concerning the A-V delay, we noted that at 75 ppm stroke volume was significantly higher in DOO than in VOO with any A-V delay ranging +/- 100 msec from the optimal one; at 120 ppm the hemodynamic benefit of DOO pacing was observed only when the programmed A-V delay was the optimal one or very near to it. In conclusion, atrio-ventricular sequential pacing allows a significant increase in LV stroke volume over single chamber ventricular pacing both at 75 and 120 ppm. Programming the optimal A-V delay is absolutely necessary to obtain this hemodynamic benefit at the higher stimulation rate.

Aged↗
PubMed1991

Dobutamine versus dipyridamole echocardiography in coronary artery disease.

Dobutamine and dipyridamole echocardiography are gaining popularity as exercise-independent stress tests for the diagnosis of coronary artery disease. To compare the feasibility, sensitivity, and specificity of dobutamine echocardiography to dipyridamole echocardiography, we conducted both tests, on different days and in random order, on 35 patients with chest pain and suspected coronary artery disease. Dobutamine was administered in scalar doses up to 40 micrograms/kg per minute and dipyridamole up to 0.84 mg/kg for 10 minutes. Dobutamine echocardiography testing was positive in eight of 16 (50%) patients with single-vessel disease and in 11 of 12 (92%) patients with multivessel disease, resulting in an overall sensitivity of 68% for the presence of coronary artery disease. Dipyridamole echocardiography testing showed the same sensitivity as dobutamine in patients with multivessel disease but a lower sensitivity (31%) in single-vessel disease, resulting in an overall sensitivity of 57%. The specificity of both tests was 100%. An ST segment shift of more than 1 mm compared with baseline was documented in 74% of the positive dobutamine echocardiography tests and in 81% of the positive dipyridamole echocardiography tests. No major complications occurred during both tests. Ventricular arrhythmias occurred in 11 patients with dobutamine and in none with dipyridamole (31% versus 0%, p less than 0.001). Thus, in our selected population dobutamine echocardiography testing demonstrated a similar overall sensitivity and specificity for the diagnosis of coronary artery disease compared with dipyridamole, with a slightly better sensitivity for single-vessel disease but a greater arrhythmogenic potential.

Angiography↗
PubMed1990

Color Doppler diagnosis of mechanical prosthetic mitral regurgitation: usefulness of the flow convergence region proximal to the regurgitant orifice.

In prosthetic or paravalvular prosthetic mitral regurgitation, transthoracic color Doppler flow mapping can sometimes fail to detect the regurgitant jet within the left atrium because of the shadowing by the prosthetic valve. To overcome this limitation, we assessed the utility of color Doppler visualization of the flow convergence region (FCR) proximal to the regurgitant orifice in 20 consecutive patients with mechanical prosthetic mitral regurgitation documented by surgery and cardiac catheterization (13 of 20 patients). In addition, we studied 33 patients with normally functioning mitral prostheses. Doppler studies were performed in the apical, subcostal, and parasternal long-axis views. An FCR was detected in 95% (19 of 20) of patients with prosthetic mitral regurgitation. A jet area in the left atrium was detected in 60% (12 of 20) of patients. In 18 of 19 patients with Doppler-detected FCR, the site of the leak was correctly identified by observing the location of the FCR. A trivial jet area was detected in eight patients with a normally functioning mitral prosthesis; in none was an FCR identified. Thus color Doppler visualization of the FCR proximal to the regurgitant orifice is superior to the jet area in the diagnosis of mechanical prosthetic mitral regurgitation. Moreover, FCR permits localization of the site of the leak with good accuracy.

Adult↗
PubMed1990

Electrocardiographic changes suggestive of myocardial ischemia elicited by dipyridamole infusion in acute rejection early after heart transplantation.

Acute cardiac rejection, syndrome X, and arterial hypertension can induce small vessel damage and, therefore, restriction of coronary reserve in the presence of normal epicardial coronary arteries. A characteristic response pattern to dipyridamole (DIP) infusion has been previously described in syndrome X and arterial hypertension: ST segment depression without any measurable systolic dysfunction. The aim of this study was to establish whether acute cardiac rejection might induce electrocardiographic alterations during DIP infusion. Changes in the 12-lead electrocardiogram and two-dimensional echocardiogram during high-dose DIP infusion (up to 0.84 mg/kg in 10 minutes) were evaluated within 24 hours of endomyocardial biopsy in 14 transplanted patients. A total of 47 biopsy-controlled DIP studies were performed within 5 weeks after cardiac transplantation. For each patient, at least 7 days elapsed between two consecutive studies. Electrocardiographic and echocardiographic tracings were analyzed without prior knowledge of endomyocardial biopsy findings. No remarkable side effects occurred in any case, so that the DIP study could be completed in all patients. A diagnostic (greater than 0.1 mV) ST segment depression was found in 11 studies. The sensitivity and specificity of DIP-induced ST segment depression for the detection of biopsy-proven acute rejection were 72% and 94%, respectively. These data show that DIP stress is feasible and safe in transplanted patients and that acute cardiac rejection can be accompanied by DIP-induced ST segment depression without detectable impairment in systolic function. These changes might provide noninvasive markers for surveillance of rejection.

Adult↗