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Biomedical subjects

Theodoros G Papaioannou

Publications and source records attributed to Theodoros G Papaioannou.

At least 19 recordsLinked to original sources
PubMed2006

Abnormal endothelial function in female patients with hypothyroidism and borderline thyroid function.

BACKGROUND: It has been suggested that hypothyroidism is associated with an increased risk for cardiovascular disease. The aim of this study was to assess non-invasively NO-dependent endothelial function of resistance arteries in subjects with hypothyroidism of varying severity. METHODS: Ninety-six female subjects (aged: 42+/-13 years) comprised the study population. Subjects were divided into five groups based on TSH levels at presentation: Group 0 (n=23) with TSH: 0.3-2.0 microU/ml, Group 1 (n=22) with TSH: 2.1-4.0 microU/ml (upper normal), Group 2 (n=18) with TSH: 4.1-10 microU/ml (subclinical hypothyroidism), Group 3 (n=22) with TSH >10 microU/ml (overt hypothyroidism). One additional group with well-controlled hypothyroidism on L-thyroxine therapy (Group 4, n=11, TSH: 0.3-2.0 microU/ml) was also studied. Endothelial function of resistance arteries was assessed by measuring forearm blood flow response during reactive hyperemia utilizing venous occlusion strain-gauge plethysmography. RESULTS: Duration of reactive hyperemia was significantly different among groups of subjects with varying hypothyroidism (83.7+/-58.3 s, 53.2+/-35.7 s, 52.8+/-47.5 s, 12.9+/-13.3 s and 69.5+/-26.2 s in Groups 0, 1, 2, 3 and 4, respectively, p<0.001, ANOVA). Duration of reactive hyperemia was significantly shorter in subjects with upper normal TSH values (Group 1) compared to controls (53.2+/-35.7 s vs. 83.7+/-58.3 s, p=0.013), while it was comparable to that of subjects with subclinical hypothyroidism (Group 2) (52.8+/-47.5 s). However, duration of reactive hyperemia in Group 1 was significantly longer compared to Group 3 (overt hypothyroidism) (53.2+/-35.7 s vs. 12.9+/-13.3 s, p=0.002). Similarly, duration of reactive hyperemia in subjects with subclinical hypothyroidism was significantly longer compared to subjects with overt hypothyroidism (52.8+/-47.5 s vs. 12.9+/-13.3 s, p=0.003). Duration of reactive hyperemia in Group 4 (well-controlled hypothyroidism on L-thyroxine therapy) did not differ significantly compared to controls. There was a highly significant linear correlation between duration of reactive hyperemia and TSH (r=-0.383, p<0.001). CONCLUSION: Endothelial dysfunction was detected in the microvasculature of patients with hypothyroidism. Duration of reactive hyperemia decreased with increasing TSH levels. Since endothelial dysfunction is a factor leading to atherosclerosis, this abnormality may partly explain predisposition of patients with thyroid failure to cardiovascular disease.

Adult↗
PubMed2006

Arterial wave reflection is associated with severity of extracoronary atherosclerosis in patients with coronary artery disease.

BACKGROUND: Arterial wave reflection is a major determinant of left ventricular function, coronary perfusion and cardiovascular risk. We investigated whether arterial wave reflection may detect atherosclerosis of peripheral arteries in patients with documented coronary artery disease (CAD). METHODS: Radial artery applanation tonometry and pulse wave analysis was performed in 184 patients with documented CAD at coronary angiography; central blood pressures and augmentation index (AI) were measured. Ankle-brachial (ABI) index and intima-media thickness (IMT) were used as indices of atherosclerosis of the lower limbs and the carotid arteries respectively. RESULTS: Patients with abnormal IMT (> 0.7 mm, first tertile) or ABI (< 0.94, first tertile) had higher AI than patients with lower IMT or higher ABI (24 +/- 17 versus 17 +/- 16% and 23 +/- 18 versus 18 +/- 13%, respectively, P < 0.05). In multivariate analysis, increasing AI was associated with age, female gender, heart rate, mean blood pressure, hyperlipidaemia, and use of statins (regression coefficient (beta) = 0.50, beta = 0.15, beta = -0.60, beta = 0.23, beta = 0.16 and beta = -0.14, respectively, P < 0.05). Increasing AI was associated with an adjusted-odds ratio of 1.035 [95% confidence interval (CI), 1.005-1.066], P = 0.02 for an abnormal IMT and of 1.08 (95% CI, 1.024-1.146), P = 0.005 for ABI after adjustment for age, gender, heart rate, height, blood pressure, atherosclerotic risk factors, obesity and medication. No relation was found between AI and Gensini score or for the number of diseased coronary vessels. CONCLUSION: Augmentation index is a marker of extensive extracoronary atherosclerosis in patients with CAD.

Aged↗
PubMed2005

Arterial stiffness assessed by pulse wave analysis in essential hypertension: relation to 24-h blood pressure profile.

BACKGROUND: Arterial stiffness is a risk factor for cardiovascular morbidity and mortality and appears to be increased in arterial hypertension. The purpose of the present study was to relate systemic arterial stiffness assessed by pulse wave analysis to variables of 24-h ambulatory blood pressure monitoring (ABPM) in patients with essential hypertension. METHODS: Seventy-two subjects with untreated mild to moderate arterial hypertension underwent evaluation with 24-h ambulatory blood pressure monitoring. In the same subjects, applanation tonometry and pulse wave analysis was performed for evaluation of systemic arterial stiffness expressed as augmentation index and estimated aortic pulse wave velocity. RESULTS: Clinic systolic blood pressure, mean heart rate during 24-h blood pressure monitoring and height were independent predictors of augmentation index and estimated aortic pulse wave velocity. The 41 patients with blunted reduction in nighttime blood pressure (nondippers) showed higher mean systolic blood pressure (p=0.02), lower systolic and diastolic blood pressure variability (p<0.001), higher pulse pressure during 24-h monitoring (p=0.05) and higher estimated aortic pulse wave velocity (p=0.03), indicating stiffer arteries in this group. CONCLUSIONS: These results suggest that blood pressure change from day- to nighttime is an important determinant of arterial stiffness assessed by pulse wave analysis; this association could contribute to the higher cardiovascular risk in nondippers.

Blood Pressure Monitoring, Ambulatory↗
PubMed2005

Rapid effect of pravastatin on endothelial function and lipid peroxidation in unstable angina.

BACKGROUND: Oxidative stress contributes to endothelial dysfunction, an important step to the pathogenesis of atherosclerosis and coronary events. Latest studies revealed the existence of pleiotropic and especially antioxidant properties of statins. We sought to examine the effects of pravastatin on lipid peroxidation and endothelial function, independently from lipid-lowering, in patients with unstable angina (UA). METHODS: Thirty-seven patients (males), 64.46+/-9.09 years, suffering from UA enrolled in the study. Patients were not on statin medication before admission and they received after randomization either 40 mg pravastatin daily (group A, n = 20), or placebo (group B, n = 17). Malondialdehyde (MDA) concentration, an index of lipid peroxidation and plaque instability, flow-mediated dilatation (FMD) of the brachial artery and blood lipids were measured on the second day of hospitalization and 10 days later. RESULTS: MDA decreased significantly in both groups (A, p = 0.008; B, p = 0.003). FMD increased significantly in group A (p = 0.007), whereas in group B it did not change. Serum lipids remained unaltered in all three groups. CONCLUSIONS: Pravastatin administration improved FMD within 10 days and this favorable effect occurred before any significant reduction in blood lipids, revealing its pleiotropic effects during the early phase of an acute coronary syndrome. Circulating lipid peroxidation products in patients with UA decreased significantly during the same period independently of endothelial function and pravastatin therapy.

Aged↗
PubMed2005

Acute effects of caffeine on arterial stiffness, wave reflections, and central aortic pressures.

Caffeine is considered to be the most widely consumed pharmacologic substance in the world. Several recent sources of evidence suggest that caffeine, besides its well-established pressor effects, provokes further alterations in arterial stiffness, wave reflections, and especially aortic blood pressures, which are often overlooked. The increasing evidence regarding the prognostic value of the latter cardiovascular factors prompted us to seek additional information concerning the relationship of aortic blood pressures to caffeine consumption. The main purpose of the present review was to evaluate the acute influence of caffeine on arterial stiffness, wave reflections, and central systolic pressures, which are involved in the pathogenesis and prognosis of cardiovascular diseases. Current evidence supports the hypothesis that caffeine influences the cardiovascular system at least acutely, not only through a peripheral blood pressure elevation but also through an increase in arterial stiffness and an enhancement of arterial wave reflections. Moreover, it seems that peripheral pressure measurements might have underestimated caffeine pressor effects, as a significantly greater response is observed in aortic pressures. The mechanisms explaining these effects of caffeine are not always clear, and neither is the role of caffeine in cardiovascular risk. However, it is concluded that strategies aiming at the control of dietary caffeine consumption merit serious consideration.

Aorta↗
PubMed2005

Red wine acutely induces favorable effects on wave reflections and central pressures in coronary artery disease patients.

BACKGROUND: To investigate red wine's acute effects on aortic pressures and arterial stiffness in patients with coronary artery disease (CAD). METHODS: Fifteen patients with CAD were recruited in a double-blind, cross-over study, which was comprised of 2 study days. Each volunteer consumed either 250 mL of regular or 250 mL of dealcoholized red wine. Wave reflections, expressed as augmentation index (AIx), as well as central and peripheral blood pressures (BP) were assessed at fast and 30, 60, and 90 min postprandially. RESULTS: Both regular and dealcoholized red wine caused a significant decrease in AIx by 10.5% +/- 1.4% (P = .001) and 6.1% +/- 1.4% (P = .011), respectively, whereas no significant change was induced in mean BP and timing of wave reflections expressing pulse wave velocity. Peripheral systolic BPs remained unaltered in both beverages, whereas a significant decrease in peripheral and central diastolic BPs was observed after the dealcoholized red wine consumption (P = .03 and P = .035, respectively). Central systolic BP was decreased after the consumption of regular (-7.4 +/- 2.4 mm Hg, P = .05) and dealcoholized red wine (-5.4 +/- 2.7 mm Hg, P = .019). CONCLUSIONS: Both types of red wine provoked favorable acute effects on wave reflections and central systolic pressures, whereas no such effect was evident at the brachial artery. Therefore, these findings could be attributed mainly to red wine antioxidant substances, rendering it a possible means of at least acute attenuation of increased wave reflections, arterial stiffness, and central pressures in patients with coronary artery disease.

Adult↗
PubMed2005

Experimental and clinical study of the combined effect of arterial stiffness and heart rate on pulse pressure: differences between central and peripheral arteries.

1. Pulse pressure (PP) constitutes an independent predictor of cardiovascular events and mortality in various populations. Heart rate (HR) and arterial stiffness, in addition to their independent predictive value for cardiovascular complications, seem to interact with regard to the modification of PP. The aim of the present study was to investigate the association of PP with HR under different levels of arterial compliance (AC), revealing their synergistic effects. 2. Seventy-one normotensive and untreated hypertensive subjects were examined. Arterial compliance was measured by the 'area' method, whereas central blood pressures and wave reflections were evaluated using the Sphygmocor system (AtCor Medical, Sydney, NSW, Australia). A hydraulic Windkessel model was also used to evaluate the independent effect of HR and AC on PP. Peripheral PP was associated only with mean pressure and AC. In contrast, central PP was further related to HR (20 b.p.m. decrease in HR resulted in central PP augmentation by 5.6 mmHg) regardless of mean pressure, stroke volume, age and gender. However, this association was statistically significant only for subjects with lower AC (< 1.1 mL/mmHg) and not for those with more compliant arteries. These findings are also in accordance with the experimental data. 3. Aortic PP is affected to a greater degree by HR changes compared with peripheral PP. This response was observed only at high levels of arterial stiffness. 4. The present study provides the first evidence regarding the combined effect of AC and HR on aortic PP, which may lead to larger clinical or epidemiological studies aiming to optimization of drug treatment and to a possible reduction of cardiovascular risk.

Arteries↗
PubMed2004

Tamoxifen improves endothelial function and reduces carotid intima-media thickness in postmenopausal women.

BACKGROUND: Tamoxifen is a selective estrogen-receptor modulator shown to improve several cardiovascular risk factors in postmenopausal women with breast cancer. In animal studies tamoxifen inhibits the progression of atherosclerosis. Although the presence of a history with tamoxifen treatment is related to a lower intima-media thickness (IMT) of the common carotid artery, data from controlled follow-up studies are lacking to support this observation. METHODS: We examined 14 postmenopausal women with early stage breast cancer with indication for tamoxifen treatment (20 mg/d) and 13 healthy postmenopausal women. Flow-mediated dilatation (FMD) of the brachial artery, combined carotid IMT, and aortic pulse wave were measured before and 6 months after treatment in the tamoxifen group and at the same times in the control group. RESULTS: FMD and IMT were significantly increased and decreased, respectively, in the treatment group compared to the control group (FMD: +2.2% +/- 0.9% vs +0.085% +/- 1%, P =.012; IMT: -0.088 +/- 0.03 mm vs +0.04 +/- 0.03 mm, P =.018, mean +/- standard error of the mean, treatment vs control group). These differences remained significant even when adjusted for age, duration of menopause, and cardiovascular risk factors. Low-density lipoprotein cholesterol was also significantly reduced after tamoxifen treatment. CONCLUSIONS: Tamoxifen treatment slows the progression of atherosclerosis in postmenopausal women with breast cancer as assessed by changes in carotid IMT. An improvement in endothelial function and blood lipid profile may be the reason for this beneficial effect.

Aged↗
PubMed2004

Monitoring of arterial stiffness indices by applanation tonometry and pulse wave analysis: reproducibility at low blood pressures.

OBJECTIVE: Aortic pulse wave analysis (PWA) reveals valuable information related to several hemodynamic characteristics mainly in normotensive and hypertensive patients. The main indices determined by PWA are augmentation index (AI) and reflection time index (RTI), which provide an indirect estimate of arterial stiffness and pulse wave velocity. The objective of the present study was to assess the reproducibility of aortic AI and RTI obtained by an automated and commercially available system (SphygmoCor) applied in patients with low blood pressures where such data are lacking. METHODS: The study population consisted of 19 patients with cardiogenic shock due to acute myocardial infarction who underwent mechanical assistance with intraaortic balloon pump. Aortic pressure waveforms were derived from peripheral waveforms--recorded by applanation tonometry of the radial artery--by applying generalized transfer functions. On every occasion, a well-trained operator performed two measurements with 2 min interval. Multiple pairs of measurements were obtained per patient in order to study a wide range of different hemodynamic conditions. Thus, a total of 91 pairs of measurements were performed and analyzed using Bland-Altman plots. RESULTS: AI and RTI ranged within 30-184% and 10-27%, respectively. Within-observer difference was 0.10 +/- 5.82% for aortic AI and 0.14 +/- 1.2% for RTI. CONCLUSION: Pulse wave analysis and radial artery tonometry can be used to measure AI and RTI with satisfactory reproducibility even in low blood pressures. Ongoing research is required to establish PWA utility in clinical practice especially at patients with low blood pressures.

Aged↗
PubMed2004

Oral folic acid enhances endothelial function in patients with hypercholesterolaemia receiving statins.

BACKGROUND: Folic acid therapy has been shown to improve endothelial function in patients with familial hypercholesterolaemia via a possible antioxidant mechanism. Data on the possible role of folic acid in hypercholesterolaemic patients receiving statins are lacking. In the present study we tested the hypothesis that folic acid supplementation improves endothelial function in patients with hypercholesterolaemia and treatment with statins. METHODS: Thirty-four hypercholesterolaemic patients receiving statins participated in the study; all subjects underwent measurement of endothelium-dependent, flow-mediated dilatation of the brachial artery and subsequently randomized to receive 5 mg of the folic acid (n=17) or placebo (n=17) for 4 weeks. Flow-mediated dilatation of the brachial artery was repeated at the end of the 4-week period. RESULTS: Folic acid and placebo groups were comparable regarding age, sex, smoking, hypertension, coronary artery disease, obesity, family history and blood lipids. Folic acid administration resulted in an improvement of flow-mediated dilatation (4.7+/-3.2% to 7.1+/-3.1%, P=0.02), whereas there was no improvement after placebo administration (5.7+/-3.8% to 5.6+/-2.2%, ns). No significant change in nitrate-induced, endothelium- independent dilatation was observed after folic acid or placebo (ns). CONCLUSIONS: Oral administration of folic acid (5 mg) for 4 weeks improves endothelial function in patients with hypercholesterolaemia treated with statins, with possible beneficial effects on the prognosis of these patients.

Administration, Oral↗
PubMed2004

Effect of ascorbic acid on forearm reactive hyperaemia in patients with hypercholesterolaemia.

BACKGROUND: This study was designed to research the effect of hypercholesterolaemia and ascorbic acid on forearm blood flow (FBF) reactive hyperaemia (RH). Reactive hyperaemia seems to be at least partly endothelium-dependent. Endothelial dysfunction has been described in patients with hypercholesterolaemia, and has been reversed with ascorbic acid administration. METHOD: Forearm blood flow was studied with venous occlusion plethsmography in 26 healthy volunteers and 46 hypercholesterolaemic patients. Hypercholesterolaemic patients were divided into two groups. Group A comprised 25 patients, who received ascorbic acid and group B comprised 21 patients, who received placebo. All subjects underwent measurement of FBF at baseline and during RH (phase A). Forearm blood flow during RH was measured every 15 seconds for three minutes. Subsequently patients in group A received 2 g of ascorbic acid orally in the form of effervescent tablets, and patients in group B received placebo orally in the same form. Forearm blood flow measurements at baseline and during RH were repeated two hours later (phase B). RESULTS: Maximal percent increase of FBF was significantly higher in healthy subjects than in hypercholesterolaemic patients (139.1+/-12.1% versus 73.1+/-11.0% respectively, P<0.05). Duration of RH was smaller in hypercholesterolaemic patients compared to normal subjects (60.9+/-17.1 seconds versus 105.6+/-10.2 seconds, P<0.05). Administration of ascorbic acid but not of placebo increased the duration of RH (69.1+/-11.1 seconds versus 104.1+/-12.2 seconds, P<0.05) but not of peak RH FBF. CONCLUSION: Hypercholesterolaemia seems to impair both the early and late phase of RH. Ascorbic acid improves only the duration of RH, possibly due to its antioxidant effect on endothelium.

Adult↗
PubMed2004

New aspects on the role of blood pressure and arterial stiffness in mechanical assistance by intra-aortic balloon pump: in-vitro data and their application in clinical practice.

Despite the well-known beneficial effects of the intra-aortic balloon pump (IABP) generally, there are still some clinical conditions accompanied by IABP ineffectiveness. The aim of this study was the investigation of the independent effects of arterial stiffness and blood pressure on acute IABP effectiveness. For this purpose, a mock circulatory system and 20 patients with cardiogenic shock due to acute myocardial infarction, were employed. It was shown that IABP acute efficiency was determined primarily by arterial compliance (AC) rather than blood pressure alone. IABP induced low hemodynamic effects in patients with systolic blood pressure > 80 mm Hg but with increased AC, whereas IABP resulted in greater hemodynamic effectiveness in cases with systolic pressure < 70 mm Hg but lower AC. The present study provides evidence concerning the hemodynamic conditions, which might lead to optimization of IABP or to the prediction of its acute hemodynamic performance, based on both measurements of AC and blood pressure.

Aged↗
PubMed2004

Endothelial dysfunction and type of cigarette smoked: the impact of 'light' versus regular cigarette smoking.

Acute cigarette smoking leads to temporary endothelial dysfunction, which is an early event in atherogenesis. Sufficient data concerning the effect of cigarettes with low tar and nicotine yield are lacking. Seventeen healthy individuals (nine women, eight men, aged 27.8 +/- 3.6 years) were subjected to evaluation of endothelial function by means of endothelium-dependent, flow-mediated dilatation (FMD) of the brachial artery, before, immediately after and 30, 60 and 90 min after smoking a regular cigarette (nicotine 0.9 mg, tar 12 mg) orthe corresponding 'light' cigarette (nicotine 0.6 mg, tar 8 mg). The following day, measurements were repeated after smoking the opposite kind of cigarette. Baseline FMD was 6.1 +/- 1.6% and 7.2 +/- 2.0% in the light and regular cigarette groups, respectively (p = NS). The overall effect of the regular cigarette over time on FMD compared with the light cigarette was significantly different (F = 3.039, p = 0.023). FMD was significantly depressed after smoking both types (light: F = 8.192, p < 0.001; regular: F = 16.698, p < 0.001). Immediately after smoking, FMD declined in both groups (light: 3.0 +/- 2.4% and regular: 1.6 +/- 3.2%, p < 0.001 and p < 0.001, respectively), and it remained significantly depressed in the regular cigarette group at 30 min (0.75+/-1.5%, p < 0.001) and 60 min (3.5 +/- 3.1%, p = 0.024), while in the light cigarette group FMD differences were abolished at 30, 60 and 90 min after smoking. In conclusion, acute smoking of both regular and light cigarettes leads to temporary vasomotor dysfunction; its duration is shorter after smoking a 'light' cigarette.

Adult↗
PubMed2003

P wave analysis indices in young healthy men: data from the digital electrocardiographic study in Hellenic Air Force Servicemen (DEHAS).

P wave analysis from the 12-lead ECG is a recent contribution of noninvasive electrocardiology. P wave analysis indices (maximum and minimum P wave duration, P wave dispersion [Pdis = Pmax-Pmin], adjusted P wave dispersion [APdis = Pdis/square root of measured leads], summated P wave duration [Psum], standard deviation of P wave duration [Psd], mean P wave duration [Pmean]) can predict atrial arrhythmias. However, the definitions of all these indices are based on few studies. The aim of this analysis was to define normal values of these indices and the examine possible associations between P wave indices and clinical variables. The study included 1,353 healthy men, 24 +/- 3 years of age, who answered a questionnaire and underwent a detailed physical examination and a digitized 12-lead surface ECG. All P wave indices were analyzed by two independent investigators. Mean values of the ECG indices were: Pmax: 96 +/- 11 ms, Pmin: 57 +/- 9 ms, Pdis: 38 +/- 10 ms, Psum: 924 +/- 96 ms, Psd: 12 +/- 3, APdis: 11 +/- 3 ms, and Pmean: 77 +/- 8 ms. Age was significantly related with Pmax (r = 0.277, P < 0.01), Pmin (r = 0.255, P < 0.001), Psum (r = 0.074, P < 0.01), and Pmean (r = 0.074, P < 0.01). All ECG indices were significantly associated with the R-R interval, and among each other. This study defined normal indices of wave duration and correlations among them. These markers may play an important predictive role in patients with atrial conduction abnormalities.

Adolescent↗
PubMed2002

Oral L-arginine improves endothelial dysfunction in patients with essential hypertension.

BACKGROUND: L-Arginine is a nitric oxide precursor, which augments endothelium-dependent vasodilatation in hypercholesterolemic humans and animals. Endothelium-dependent vasodilation is attenuated in patients with hypertension; however the effects of oral L-arginine on endothelial function of the conduit arteries in patients with essential hypertension have not previously been investigated. METHODS: In a prospective randomized double blind trial, 35 patients with essential hypertension received either 6 g L-arginine (18 subjects) or placebo (17 subjects). Patients were examined for flow-mediated endothelium-dependent dilatation of the brachial artery before and 1.5 h after administration of L-arginine or placebo. At the end of the protocol the nitrate-induced, endothelium-independent vasodilatation was evaluated. RESULTS: Two groups of L-arginine and placebo were similar regarding age, sex, blood lipids, smoking, diabetes, coronary artery disease, body mass index, intima-media thickness of the common carotid artery, clinics blood pressure and baseline brachial artery parameters. Administration of L-arginine or placebo did not change significantly heart rate, blood pressure, baseline diameter, blood flow or reactive hyperemia. L-Arginine resulted in a significant improvement of flow-mediated dilatation (1.7+/-3.4 vs. 5.9+/-5.4%, P=0.008) while placebo did not significantly change this parameter (3.0+/-2.7 vs. 3.1+/-2.2%, P=ns). The effect of L-arginine on flow-mediated dilatation was significantly different from the effect of placebo (P=0.05). L-Arginine did not significantly influence nitrate-induced dilatation (16+/-6.9 vs. 17.7+/-6.7%, P=ns). CONCLUSIONS: Oral administration of L-arginine acutely improves endothelium-dependent, flow-mediated dilatation of the brachial artery in patients with essential hypertension. The long-term effects of L-arginine in these patients require further investigation.

Administration, Oral↗
PubMed2002

Arterial compliance is a main variable determining the effectiveness of intra-aortic balloon counterpulsation: quantitative data from an in vitro study.

Quantitative data concerning the effect of arterial compliance (AC) on the effectiveness of intra-aortic balloon counterpulsation (IABC) are lacking. The main objective of this study was to investigate the relationship between AC and IABC performance. For this purpose we constructed a Windkessel, lumped-element, hydraulic model of the systemic circulation. The model consisted of a left ventricular assist device (LVAD), a compliance chamber, a peripheral resistor and two open reservoirs. Two Datascope Driving systems were used to operate the LVAD and intra-aortic balloon. We studied the effect of arterial compliance on the effectiveness of IABC at different levels of mean pressure (55, 75 and 95 mmHg) and heart rates (80, 100, 120 bpm). Three indices were used to evaluate IABC performance: the reduction of systolic and end-diastolic "arterial" pressure and the augmentation of diastolic pressure, induced by the IABC. A 22% decrease in AC (1.8-1.4 ml/mmHg) lead to a 30-40% increase in the indices of IABC performance, independently from pressure. In conclusion, arterial compliance significantly affects IABC efficacy and it could be considered as a further clinical criterion to decide IABC application.

Aorta↗
PubMedDate not supplied

Basic principles of the intraaortic balloon pump and mechanisms affecting its performance.

The intraaortic balloon pump (IABP) is the single most effective and widely used device for temporary mechanical assistance of the failing heart. Although the principles underlying IABP function are simple, various biologic factors often determine its performance in a particularly complicated way. We briefly describe the basic disciplines of counterpulsation by IABP and the induced hemodynamic changes while clarifying the biologic mechanisms that play a crucial role in the modification of IABP acute hemodynamic performance.

Blood Pressure↗