Biomedical subjects

S F Stamatelopoulos

Publications and source records attributed to S F Stamatelopoulos.

At least 37 records · Page 2Linked to original sources

PubMed1999

Mechanical ventilation in conjunction with the intra-aortic balloon pump improves the outcome of patients in profound cardiogenic shock.

OBJECTIVE: To examine the effects of mechanical ventilation with positive end-expiratory pressure (PEEP), in conjunction with the intra-aortic balloon pump (IABP), on the outcome of patients in profound cardiogenic shock. PATIENTS: Twenty-eight consecutive patients presenting with myocardial infarction complicated by cardiogenic shock refractory to medical therapy, including dobutamine, dopamine and fluid administration. Eighteen patients were assisted by the IABP alone (IABP group), and ten patients by the IABP plus controlled mechanical ventilation with PEEP set at 10 cmH(2)O (IABP + CMV group). RESULTS: Weaning from mechanical assistance was accomplished in 8 out of 18 patients in the IABP group versus 9 out of 10 patients in the IABP + CMV group (p = 0.04). Ultimately, 5 of 18 patients in the IABP group were discharged from the hospital versus 8 of 10 patients in the IABP + CMV group (p = 0. 01). CONCLUSION: Mechanical ventilation with PEEP at 10 cmH(2)O supplements the IABP and may improve the survival rates of patients suffering from cardiogenic shock.

Confounding Factors, Epidemiologic↗

PubMed1999

Amiodarone concentration in human myocardium after rapid intravenous administration.

Intravenous amiodarone has been found useful in the emergent management of life-threatening arrhythmias. Experimental studies have shown that its electrophysiologic effects are proportional to its myocardial concentration. However, early after its intravenous administration, the extent of the concentration of amiodarone in the human myocardium, the site of its action, is not well known. This study was performed to measure the myocardial concentration of amiodarone shortly after rapid intravenous injection. Amiodarone, 150 mg, was injected over 15 seconds intravenously into 9 patients, 52 +/- 9 years of age, weighing between 65 and 98 kg (mean = 81 +/- 15.6). All patients suffered from idiopathic dilated cardiomyopathy, were in NYHA functional class II, and the mean left ventricular ejection fraction was 21 +/- 6%. Right ventricular endomyocardial biopsy, required for the establishment of the diagnosis, was performed 2-5 minutes after drug administration for measurements of its myocardial concentration. Plasma concentrations of amiodarone were also measured at 2, 5, 10, and 60 minutes, and measurements of right heart hemodynamics were made 2 and 10 minutes after the injection. At 2.5 +/- 1.2 minutes after amiodarone administration, the mean myocardial concentration was 95.7 +/- 67.4 micrograms/g (range, 16-175), and the myocardial/plasma amiodarone ratio was 5.05 +/- 5.01. Heart rate increased from 82 +/- 17 to 90 +/- 13 beats/min (P < 0.05), and systolic blood pressure decreased from 132 +/- 19 to 118 +/- 17 mmHg (P < 0.03). The extent of myocardial fibrosis was 5.13 +/- 6.55% (range, 0.3-17.5%). Intravenous amiodarone (150 mg) accumulates rapidly in the human myocardium. This pharmacokinetic characteristic probably explains its acute efficacy in the treatment of life-threatening arrhythmias.

Adult↗

PubMed1999

A pressure-time index' for assessing the severity of essential hypertension.

OBJECTIVE: A new derivative of 24 h ambulatory blood pressure monitoring (ABPM) is introduced and its association with left ventricular mass index (LVMI) in essential hypertension is examined. PATIENT: population One hundred and fifty-three previously untreated essential hypertension patients. METHODS: Patients underwent casual blood pressure (BP) readings, 24 h ABPM and left ventricular echocardiographic assessment The following 24 h awake and sleep ABP variables were calculated: mean systolic and diastolic BP, systolic and diastolic BP loads (percentage of systolic readings > 140/120 mmHg (day/ night) and diastolic readings > 90/80 mmHg (day/night)), standard deviation of systolic and diastolic ABP and nocturnal fall of systolic BP, as well as the integrated areas under the ABP curve. The area under the BP curve divided in horizontal slices was accurately modelled by a sigmoid curve. The parameters controlling the shape of the curve and in particular that regarding its 'slope' is hereafter called the 'pressure-time index'. RESULTS: 'Systolic pressure-time index 24 h' (SPTI24) is related to left ventricular mass index (multivariate analysis, P= 0.008). Using either partial correlation coefficients or a multivariate analysis, SPTI24 is related to left ventricular mass index, independently of age, casual blood pressure, mean systolic and diastolic ABP, systolic and diastolic BP loads, BP variability (standard deviation (SD), nocturnal fall of systolic BP) and integrated area under the curve (multivariate analysis, P= 0.004). CONCLUSIONS: In essential hypertension, the SPTI24 is related to LVMI independently of age, casual blood pressure, integrated area under the curve or any other derivative of 24 h ABPM, and might be used to assess the extent of hypertensive load.

Adolescent↗

PubMed1998

Peripheral vascular endothelial dysfunction in patients with angina pectoris and normal coronary arteriograms.

OBJECTIVES: We sought to determine endothelium-dependent vasodilator function in the brachial artery of patients with microvascular angina pectoris. BACKGROUND: Previous studies suggest the presence of endothelial dysfunction of the coronary microcirculation in patients with microvascular angina pectoris. It is not known whether endothelial dysfunction in these patients is a generalized process or whether it is confined to the coronary microcirculation only. METHODS: In 11 women (mean [+/-SD] age 60.1 +/- 7.8 years) with microvascular angina (anginal pain, normal epicardial coronary arteries, positive exercise stress test), endothelium-dependent vasodilation was assessed in the brachial artery by measuring the change in brachial artery diameter in response to hyperemic flow. Results were compared with 11 age- and gender-matched patients with known three-vessel coronary artery disease and 11 age- and gender-matched healthy control subjects. In all subjects, the intima-media thickness (IMT) of the common carotid artery was also measured. RESULTS: Flow-mediated dilation (FMD) was comparable in patients with microvascular angina and coronary artery disease (1.9 +/- 2.5% vs. 3.3 +/- 3.3%, p = NS) but was significantly lower in patients with microvascular angina than in healthy control subjects (1.9 +/- 2.5% vs. 7.9 +/- 3%, p < 0.05). IMT was significantly lower in patients with microvascular angina than in those with coronary artery disease (0.64 +/- 0.08 vs. 1.0 +/- 0.28 mm, p < 0.05) and was comparable between patients with microvascular angina pectoris and healthy control subjects (0.64 +/- 0.08 vs. 0.56 +/- 0.14 mm, p = NS). IMT > or = 0.8 mm was observed in 1 of 11 patients with microvascular angina, 1 of 11 control subjects and 10 of 11 patients with coronary artery disease. CONCLUSIONS: These findings suggest that endothelial dysfunction in microvascular angina is a generalized process that also involves the peripheral conduit arteries and is similar to that observed in atherosclerotic disease. IMT could be helpful in discriminating patients with microvascular angina and atherosclerotic coronary artery disease.

Aged↗

PubMed1998

New method for placement of intracoronary stents in order to avoid their embolization in the intravascular space.

Stent dislodgment from the delivery catheter is a well-known complication of angioplasty with stent implantation. The aim of our study was to investigate the feasibility, effectiveness, and safety of a new technique of intracoronary stent implantation in order to avoid stent loss in the intravascular space. Fifty consecutive patients were candidates for angioplasty and stent placement. During angioplasty, a technique was followed according to which the guide wire "hindered" the dislodgment of the stent from the balloon catheter. Successful angioplasty and stent placement were performed in 46 out of 50 patients (92% success rate). In three cases of failure of stent implantation, the stent moved onto the balloon catheter; however, this was impeded by the guide wire. One non-Q-wave myocardial infarction occurred. No major complications (Q-wave myocardial infarction, CABG, or death) were observed. In conclusion, the technique applied was feasible enough, safe, and effective. However, the appropriate modification of its "hardware" will render it even more feasible and user-friendly.

Adult↗

PubMed1998

Nonsurgical infarctectomy in acute experimental myocardial infarction.

This study examines whether a catheter mounted left intraventricular balloon may prevent left ventricular (LV) dysfunction following acute experimental myocardial infarction. In 10 anesthetized pigs, multiple coronary arterial ligations were applied around the apex of the heart. LV end-diastolic pressure (LVEDP), aortic flow (AF), and LV long and short axis fractional shortening (FS) were measured before and at 15 min intervals after ligations. At the 60th min after ligation, the LV long axis FS and AF decreased by 7.2 +/- 2.6% (p < 0.05) and 13.25 +/- 2.68% (p < 0.01), respectively, and the LVEDP increased by 4.3 +/- 1.1 mm Hg (p < 0.01) while no change was noted in the LV short axis FS. An intraventricular catheter mounted nonpulsating balloon was positioned over the endocardium of the infarcted area at the LV apex. Inflation of the nonpulsating balloon to an optimal volume, which was found to be equal to 8-10% of the LV end-diastolic volume, resulted in a reduction (by 3.8 +/- 1.2 mm Hg, p < 0.01) of the already increased LVEDP and in an increase (by 6.6 +/- 2.1%, p < 0.05) in the LV short axis FS while no statistically significant change was noted in the AF and LV long axis FS. It is concluded that an intraventricular catheter mounted balloon patch positioned over the endocardium of the infarcted area may ameliorate early LV dysfunction, possibly by interfering with the functional geometry of the LV contraction.

Animals↗

PubMed1998

Impaired endothelium-dependent vasodilatation in women with previous gestational diabetes.

OBJECTIVE: To assess whether otherwise healthy women with a history of gestational diabetes mellitus (GDM) may have abnormalities in endothelial function at a very early stage, before glucose intolerance occurs. RESEARCH DESIGN AND METHODS: A total of 33 women with previous GDM (17 nonobese [BMI < 27] and 16 obese [BMI > or = 27]) and 19 healthy nonobese women were examined. A 75-g oral glucose tolerance test was performed, and insulin levels and biochemical parameters were also measured. Using high-resolution ultrasound, we measured vasodilatory responses of the brachial artery during reactive hyperemia (endothelium-dependent vasodilatation), and after nitroglycerin administration, an endothelium-independent vasodilator. RESULTS: Flow-mediated dilatation (FMD) was significantly and equally decreased in both groups of women with previous GDM, compared with control subjects (1.6 +/- 3.7% in the nonobese GDM group and 1.6 +/- 2.5% in the obese GDM group vs. 10.3 +/- 4.4% in control subjects, P < 0.001). FMD correlated inversely with serum uric acid levels, BMI, serum total cholesterol, and basal insulin resistance (homeostasis model assessment). Nitrate-induced dilatation was significantly decreased only in the obese GDM group compared with control subjects, (21.4 +/- 5.1 vs. 27.9 +/- 9.5, P < 0.05). CONCLUSIONS: Endothelial dysfunction, which is considered as a very early index of atherogenesis, is already present in both obese and nonobese women with a history of GDM, even when they have normal glucose tolerance.

Adult↗

PubMed1998

Itraconazole for the treatment of pulmonary aspergillosis in heart transplant recipients.

The objective of this study was to evaluate the effects of itraconazole as a first choice drug in the treatment of pulmonary aspergillosis in heart transplant recipients. Heart transplant recipients suffering from invasive pulmonary aspergillosis were included in this study. Group 1 included 4 patients treated with i.v. itraconazole (Janssen Pharmaceutica) 400 mg daily, as a first choice drug for 28 d. Itraconazole was discontinued and amphotericin-B was started before the 28th day if clinical or radiographic worsening was observed. Group 2 included 3 patients treated with amphotericin-B as a first choice drug. Itraconazole was discontinued in all patients of Group 1 after 12-26 d of treatment because of radiographic worsening (n = 3) or combined clinical and radiographic worsening (n = 1). Subsequent treatment with amphotericin-B resulted in improvement of all patients. On a 5-yr follow-up period no relapse of aspergillosis was observed in 3 of them. The fourth patient expired from cerebral hemorrhage. The 3 patients of Group 2 treated with amphotericin-B showed a gradual improvement, and all were doing well on a 2-yr follow-up. In conclusion, in our study population consisted of heart transplant recipients amphotericin-B was superior to itraconazole in the treatment of invasive pulmonary aspergillosis.

Adult↗

PubMed1998

The efficacy of the high volume counterpulsation technique at very low levels of aortic pressure.

BACKGROUND: The objective of the present study was to identify the hemodynamic variables, that preclude the effectiveness of the counterpulsation technique. METHODS: In order to achieve high counterpulsation volume two devices were used simultaneously. The para-aortic counterpulsation device pumping 60-70 ml was implanted on the ascending aorta, and the intra-aortic balloon (20 ml) was placed in the descending aorta of 14 dogs with severe cardiogenic shock. Both devices were synchronized to provide aortic diastolic augmentation. The mechanical assistance provided by these devices was considered adequate when the mean aortic pressure during the supportive period was at least 50 mmHg, a pressure compatible with life. RESULTS: The mechanical assistance provided by the two devices was adequate in none (0%) of the cases with a systolic aortic pressure below 30 mmHg (Group I), in 71% of the cases with a systolic aortic pressure between 30-56 mmHg (Group II), and in 100% of the cases with a systolic aortic pressure above 56 mmHg (Group III). In group II the left ventricular end-diastolic pressure was higher in the cases responding adequately to mechanical assistance (Subgroup IIa) than in the ones where no adequate response was obtained (Subgroup IIb). CONCLUSIONS: The very low levels of the systolic aortic pressure was the most important factor precluding the adequate effectiveness of the counterpulsation technique.

Animals↗

PubMed1996

Detection of coronary artery disease in the presence of left ventricular atrophy.

To evaluate the accuracy of exercise echocardiography for the recognition of coronary artery disease in the presence of left ventricular hypertrophy 70 patients were studied. Significant coronary artery disease was present in 25 patients and left ventricular hypertrophy had 29 patients. All patients underwent an exercise ECG and echocardiographic test during which cine-loop digitized echocardiography was obtained. Wall motion was analyzed and a regional wall motion score index was calculated. The overall sensitivities of exercise ECG and echocardiography for detecting coronary artery disease were 60% and 64%, respectively, and the specificities were 49% and 78%, respectively. In patients with left ventricular hypertrophy the specificity of exercise echocardiography was higher (71%) compared to exercise ECG (21%) while in patients without hypertrophy the sensitivity was higher (70% vs. 40%, respectively). Of the 19 patients with a non-diagnostic stress ECG, echocardiography correctly identified 100% of those with coronary artery disease but only 53% of those without disease. It is concluded that exercise digital echocardiography represents a good diagnostic alternative to the exercise ECG for identifying coronary artery disease in the presence of left ventricular hypertrophy and should be useful in patients with a non-diagnostic exercise ECG.

Blood Pressure↗

PubMed1996

Treating severe cardiogenic shock by large counterpulsation volumes.

BACKGROUND: Intraaortic balloon pumping is known to be ineffective in severe cardiogenic shock. The efficacy of balloon volumes larger than those commonly used is examined. METHODS: In 18 dogs with severe experimental cardiogenic shock (systolic aortic pressure < 60 mm Hg, aortic flow < 45 mL.min-1.kg-1) the effect of three intraaortic balloon volumes (15, 30, and 45 mL) and a 60-mL paraaortic pump was examined. RESULTS: The 45-mL balloon covering the full length of the aorta induced the highest (+ 12.4 +/- 2.2 mL.min-1.kg-1; mean +/- standard error of the mean) and the 15-mL balloon the lowest increase in aortic flow (F = 14.6, p < 0.0001). Only the 45-mL balloon increased (p < 0.05) urine output and renal artery flow. The 60-mL paraaortic pump induced the highest (F = 10.72, p < 0.002) increase (+ 36.6 +/- 6.5 mL.min-1.kg-1) in aortic flow compared to the three balloons. An 80- to 100-mL paraaortic pump maintained the life of 3 patients in severe cardiogenic shock for 4 hours, 8 days, and 54 days, whereas a 40-mL conventional balloon was completely ineffective. CONCLUSIONS: Experimental and clinical data indicate that the effectiveness of intraaortic balloon pumping in severe cardiogenic shock may be improved by increasing the volume of the balloon (i.e., until it fully occupies the aorta).

Animals↗

PubMed1996

Left intraventricular balloon pump optimization during intractable cardiac arrest.

This work aims to determine optimal balloon shape and volume during left intraventricular balloon pumping (IABP) in the fibrillating dog heart. A balloon volume equal to the left ventricular end-diastolic volume (LVEDV) maintained a higher systolic aortic pressure and flow (106.4 +/- 2.7 mmHg and 84.7 +/- 2.35 ml/kg/min, x +/- SEM, respectively) than a 25% smaller (97.8 +/- 3.3 mmHg, P = 0.002 and 63.7 +/- 4.1 ml/kg/min, P = 0.002, respectively) or a 25% larger balloon (87.4 +/- 2.3 mmHg, P = 0.002 and 70.9 +/- 3.4 ml/kg/min, P = 0.002, respectively). Among 5 different balloon shapes tested, a pear-shaped balloon inflated from the apex to the base of the left ventricle induced the highest (P varying from 0.042 to 0.01, compared to the remaining balloon shapes) systolic aortic pressure and flow (104.6 +/- 4.5 mmHg and 77.9 +/- 1.7 mg/kg/min, respectively). In conclusion, a pear shaped balloon, inflated to a volume equal to the LVEDV, from the apex to the base of the left ventricle, induced an optimal hemodynamic effect during LVBP.

Analysis of Variance↗

PubMed1990

Effect of 24-hour blood pressure and heart rate variations on left ventricular hypertrophy and dilatation in essential hypertension.

This study correlates variables derived from blood pressure (BP) and heart rate (HR) monitoring with the degree of left ventricular structural changes in essential hypertension. Forty patients with mild-to-moderate hypertension according to World Health Organization criteria underwent 24-hour ambulatory monitoring. Echocardiographic (posterior wall and interventricular septum thickness, left ventricular mass) or ECG (SV1 + RV5) indices of hypertrophy were significantly (p less than 0.01) correlated (positive correlations) with derivatives of BP monitoring (mean systolic and diastolic BP values) but not with HR derivatives. Echocardiographic indices of dilatation (left ventricular end-diastolic volume and diameter) were significantly (p less than 0.01 to less than 0.001) correlated (negative correlations) with derivatives of HR monitoring (mean HR values, mainly during the night) but not with BP derivatives. It is concluded that in essential hypertension, left ventricular hypertrophy depends on mean 24-hour systolic and diastolic BP values, whereas left ventricular dilatation appears to be more prominent in patients with bradycardia mainly during the night.

Adult↗

PubMed1989

Intraventricular plus intra-aortic balloon pumping during intractable cardiac arrest.

A method is presented for maintaining aortic flow by mechanical means during intractable cardiac arrest. A spherical balloon was inserted into the left ventricle while the usual intra-aortic balloon was introduced into the thoracic aorta. Ventricular fibrillation was induced by direct current. The pumps operating the two balloons were adjusted to inflate the intraventricular balloon during one third of the pumping cycle and the intra-aortic balloon during the next two thirds of the same cycle. The intraventricular balloon capacity varied from 40 to 110 ml (six dogs weighing 16-24 kg) while the intra-aortic balloon capacity was 20 ml. An optimal pumping rate of 75 beats/min maintained an aortic flow of 0.9-1.5 ml/beat/kg and a mean pressure into the brachiocephalic trunk of 110 +/- 12.5 mm Hg (mean +/- SD). These experimental data indicate that an easily applied mechanical device system (needing no extracorporeal circulation) may be used to bridge the time between intractable cardiac arrest and implantation of an artificial heart or transplantation.

Animals↗

PubMed1980