Biomedical subjects

John Dernellis

Publications and source records attributed to John Dernellis.

9 recordsLinked to original sources

PubMed2006

Left atrial function in patients with a high C-reactive protein level and paroxysmal atrial fibrillation.

OBJECTIVE: We evaluated left atrial dimensions and function in high C-reactive protein (CRP) patients with paroxysmal atrial fibrillation. BACKGROUND: In patients with increased plasma levels of CRP left atrial dysfunction may enhance the occurrence of arrhythmias. METHODS: Two-dimensional and pulsed Doppler echocardiography, were performed in 20 consecutive patients with high CRP levels and paroxysmal atrial fibrillation (group CRf) and in 20 patients with high CRP levels without this arrhythmia (group CR). Twenty normal subjects (group N) were also investigated. Groups were matched for age and gender. RESULTS: CRP was increased in the CRf (median = 1.03 mg/dl), CR (median = 0.84 mg/dl) and N groups (median = 0.23 mg/dl), (p < 0.001) for all comparisons. The CRf, CR and N groups had similar systolic and diastolic blood pressure, left ventricular mass index, left ventricular ejection fraction, isovolumic relaxation time and peak early and late transmitral Doppler flow velocities. Maximal left atrial volume was greater only in the CRf group (54.4 +/- 6.3 ml) compared with the N group (50.3 +/- 4.9 ml, p < 0.05). Left atrial volume preceding atrial contraction was similar in all groups, p=NS. Left atrial minimal volume decreased from 23.0 +/- 1.8 ml in the CRf group, to 19.8 +/- 1.8 ml in the CR group, p < 0.001 and to 18.1 +/- 2.1 ml in the N group, (p < 0.02). The passive emptying fraction of the CRf and CR groups was comparable to that of normal subjects. The CRf group had a decreased left atrial active emptying fraction (0.25 +/- 0.08) compared with the CR (0.36 +/- 0.09) and N groups (0.39 +/- 0.08), p < 0.001 for both comparisons. The reservoir fraction was decreased only in the CRf group compared to normal subjects (1.37 +/- 0.25 vs. 1.82 +/- 0.43, p < 0.001). CONCLUSIONS: These results suggest that the occurrence of paroxysmal atrial fibrillation in patients with a high CRP level is associated with enlargement of the left atrium, depression of its contractile function and is independent of left ventricular hypertrophy and function. The mechanisms linking these variables remain undefined.

Aged↗

PubMed2005

Effects of C-reactive protein and the third and fourth components of complement (C3 and C4) on incidence of atrial fibrillation.

Although C-reactive protein (CRP) is a major cardiovascular risk factor, its association with atrial fibrillation (AF) remains controversial. This study explored whether the CRP-related incidence of AF is modified by serum markers of inflammation in a population-based cohort with follow-up data. Serum CRP and 2 components of the complement system (C3 and C4) were determined in 1,011 healthy patients (25 to 64 years old). The incidence of AF was compared between groups defined by levels of CRP, C3, and C4. The follow-up time was 4 years. A high complement level was defined as either C3 or C4 in the top quartile. High CRP was associated with high complement components. An increased CRP level was associated with an increased incidence of AF. The complement components modified these associations. After risk factor adjustment, those with high CRP and high complement components had a significantly higher risk of AF (relative risk 3.0, 95% confidence interval 2.0 to 4.2) than those with normal CRP and low complement levels. In the absence of a high complement level, a high CRP level was not significantly associated with AF (relative risk 1.1, 95% confidence interval 1.0 to 1.4). In conclusion, high CRP levels are associated with high serum levels of complement components. These proteins increase the CRP-related incidence of AF. In the absence of elevated complement components, no statistically confirmed association was found between a high CRP level and AF.

Adult↗

PubMed2005

Aortic stiffness is an independent predictor of progression to hypertension in nonhypertensive subjects.

Aortic stiffness may predict progression to hypertension beyond classic risk factors. In a longitudinal study, we assessed the predictive value of aortic stiffness on future hypertension in nonhypertensive subjects with blood pressure (BP) <140/90. Aortic stiffness was determined by echocardiography at baseline in 2512 subjects. The follow-up time was 4 years. A stepwise increase in hypertension incidence occurred across the male and older participants: 3.8% of young female individuals, 11.5% of young male, 26.1% of old female, and 58.8% of old male subjects progressed to hypertension over 4 years. In multivariate analysis, aortic stain, distensibility, and stiffness index (beta) remained significantly associated with the progression to future hypertension after adjustment to classic risk factors in men and women and in young and old populations. This study provides the first direct evidence to our knowledge in a longitudinal study that aortic stiffness is an independent predictor of progression to hypertension in nonhypertensive individuals.

Adult↗

PubMed2005

Effect of C-reactive protein reduction on paroxysmal atrial fibrillation.

BACKGROUND: C-reactive protein (CRP) lowering is associated with a reduction in recurrent and permanent atrial fibrillation. This study sought to determine whether CRP lowering also results in a reduction of paroxysmal atrial fibrillation (PAF) during daily life. METHODS AND RESULTS: We enrolled 80 patients with proven PAF, CRP between 0.8 and 13 mg/L, and at least 1 episode of PAF on ambulatory electrocardiographic monitoring. Forty patients were randomized to placebo (placebo group) and 40 to atorvastatin (treatment group). Plasma CRP levels and ambulatory monitoring were repeated after 4 to 6 months of therapy. The 2 groups were comparable with respect to baseline characteristics, number of episodes of PAF, and baseline plasma CRP levels. The treatment group had lower median CRP levels at study end and experienced a significant reduction in the number of episodes of PAF compared with the placebo group. Paroxysmal atrial fibrillation was completely resolved in 26 (65%) of 40 patients in the treatment group versus 4 (10%) of 40 in the placebo group. The treatment group exhibited a highly significant reduction in PAF (P < .001). By logistic regression, treatment with atorvastatin was an independent predictor of PAF resolution. CONCLUSIONS: C-reactive protein lowering with atorvastatin appears to be effective in eliminating PAF during daily life in a significant proportion of patients.

Adult↗

PubMed2005

Assessment of left atrial input impedance in normal subjects and in hypertensive patients.

BACKGROUND: To assess left atrial (LA) input impedance in patients with signs and/or symptoms of heart failure and normal left ventricular ejection fraction, transesophageal Doppler pulmonary venous (PV) flow velocity and pulmonary capillary wedge pressure (PCWP) were studied in 20 patients and compared to 20 matched normal controls. METHODS: LA impedance was calculated as the ratio of harmonic terms of the PCWP (measured by right heart catheterization) to the corresponding harmonic terms of PV flow (measured by transesophageal Doppler echocardiography). Eight harmonics were analyzed. RESULTS: Left ventricular mass index (LVMI, p<0.001), heart rate (p<0.05), systolic and diastolic blood pressure (p<0.001), isovolumic relaxation time (IVRT, p<0.001), peak A transmitral flow velocity (p<0.001), peak reversal atrial PV flow velocity (p<0.001) and LA diameter (p<0.001) were increased in patients compared to controls. Spectra of impedance moduli were displaced upwards and to the right. The increase in the impedance moduli was observed at all frequencies of the first to seventh harmonic components (p<0.001). In multivariate tests LVMI (p=0.003), IVRT (p=0.001), and LA diameter (p=0.007) had a significant effect on all harmonic components of the impedance moduli (adjusted R2=0.970 to 0.999, p<0.001). CONCLUSIONS: LA input impedance derived from data obtained invasively and semi-invasively represents left ventricular diastolic function. Resistance to left ventricular filling is increased in hypertensive patients.

Aged↗

PubMed2005

Effects of levosimendan on restrictive left ventricular filling in severe heart failure: a combined hemodynamic and Doppler echocardiographic study.

BACKGROUND: A restrictive pattern of left ventricular filling is often present in patients with severe heart failure. Although the hemodynamic effects of levosimendan have been studied, the effects of levosimendan on LV filling pattern have not been investigated. METHODS: Pulsed-wave Doppler mitral (transthoracic) and pulmonary venous flow (transesophageal) velocity curves were recorded in 30 patients with a restrictive pattern of left ventricular filling with New York Heart Association class III or IV heart failure who had a documented left ventricular ejection fraction < 30% by echocardiography and received a 0.1 microg/kg/min infusion of levosimendan for 24 h. RESULTS: Levosimendan caused significant (p < 0.001) increases in stroke volume (from 46 +/- 4 to 57 +/- 4 mL) and decreases in pulmonary capillary wedge pressure (from 21 +/- 1 to 15 +/- 1 mm Hg). The E wave decreased (from 96 +/- 7 to 71 +/- 5 cm/s), and the A wave increased (from 40 +/- 4 to 46 +/- 4 cm/s). Moreover, deceleration time was increased (from 112 +/- 7 to 189 +/- 14 ms). The S wave of pulmonary venous flow was increased (from 38 +/- 3 to 60 +/- 3 cm/s), and atrial reversal was decreased (from 36 +/- 2 to 29 +/- 2 cm/s). All changes were significant (p < 0.001). Using stepwise linear regression analysis, we found that the percentage changes of the early/late transmitral diastolic peak flow velocity (E/A) ratio and the percentage changes of the isovolumetric relaxation time were independent predictors of the increase in cardiac output. Furthermore, the percentage changes of the systolic/diastolic ratio and the percentage changes of the E/A ratio were independent predictors of the decrease in pulmonary capillary wedge pressure. CONCLUSIONS: Treatment with levosimendan improved measures of left ventricular diastolic function. Consequently, left ventricular stroke volume was increased.

Anti-Arrhythmia Agents↗

PubMed2004

Relationship between C-reactive protein concentrations during glucocorticoid therapy and recurrent atrial fibrillation.

BACKGROUND: Little direct information is available on the effect of C-Reactive Protein (CRP) lowering on the reduction of recurrent atrial fibrillation (AF). METHODS AND RESULTS: We compared low-dose glucocorticoid therapy (16 mg methylprednisolone for 4 weeks tapered to 4 mg for 4 months) and placebo in 104 patients who had experienced persistent AF with a median concentration of CRP 1.14 mg/dL (min=0.01, max=2.58). Methylprednisolone reduced recurrent AF (primary end-point) from 50% in the placebo group to 9.6% in the glucocorticoid group and permanent AF (expanded end-point) from 29% in the placebo group to 2% in the glucocorticoid group. Survival distributions for methylprednisolone were significantly different (for both primary and expanded end-point, P < 0.001). In multivariate Cox analysis, average CRP concentrations during follow-up were significant predictors of the primary end-point, with a relative risk 6.72 (P = 0.006) and the expanded end-point, with a relative risk of 11.67 (P = 0.0006). CONCLUSIONS: CRP concentration is a risk factor for recurrent and permanent AF. Methylprednisolone successfully prevents recurrent and permanent AF.

Aged↗

PubMed2002

Effects of thyroid replacement therapy on arterial blood pressure in patients with hypertension and hypothyroidism.

BACKGROUND: Hypothyroidism is frequently accompanied by cardiac dysfunction, increased vascular resistance, and a greater prevalence of hypertension. Treatment of hypothyroidism may lead to normalization of blood pressure, although some patients may exhibit sustained hypertension. The mechanism of this condition may be the alterations in aortic stiffness. METHODS: Aortic stiffness was studied in 30 patients who never received treatment for hypertension or hypothyroidism, 15 patients with normal blood pressure and hypothyroidism, and 15 patients with hypertension and normal thyroid function. Thirty healthy age- and sex-matched subjects with normal thyroid function served as control subjects. Aortic diameter evaluated by M-mode echocardiography and blood pressure measured by a sphygmomanometer were used to calculate aortic stiffness index. RESULTS: Patients with high blood pressure and hypothyroidism, those with normal blood pressure and hypothyroidism, and those with hypertension and normal thyroid function showed increased aortic stiffness index (18.8 +/- 6.4, 11.7 +/- 3.5, and 19.2 +/- 5.3 vs 9.5 +/- 2.7; P <.001) compared with control subjects. In 15 patients with hypertension and hypothyroidism, levothyroxine therapy showed only a small decrease in blood pressure (151/105 +/- 9/9 mm Hg, group A). The remaining 15 patients showed complete normalization of blood pressure (118/83 +/- 8/3 mm Hg, group B). Aortic stiffness index was increased in group A compared with group B both before and after treatment (before, 24.0 +/- 4.1 vs 13.7 +/- 3.2; and after, 22.3 +/- 4.2 vs 11.1 +/- 2.9; P <.001 for both comparisons). Felodipine was given to patients in group A after levothyroxine was administered, resulting in normalization of blood pressure and a significant decrease of aortic stiffness index (P <.001). Aortic stiffness index was decreased in patients with hypothyroidism and hypertension after administration of levothyroxine (9.5 +/- 2.2; P <.001) and felodipine (14.5 +/- 7.5; P <.001) therapy, respectively. Percent changes in systolic blood pressure showed a significant correlation with percent changes in aortic stiffness index in all patients (r = 0.65, P <.001). After multivariate adjustment, aortic stiffness index (odds ratio = 1.9932; confidence interval = 1.1481 to 3.4605) was significantly associated with incomplete normalization of blood pressure. CONCLUSIONS: Patients with hypertension and hypothyroidism have increased aortic stiffness. Aortic stiffness is decreased in all patients, whereas hypertension is completely reversible in 50% of patients by hormone replacement therapy. Sustained hypertension may be due to increased aortic stiffness.

Adult↗

PubMed1999

Evaluation of the Left Atrial Performance Using Acoustic Quantification.

In most clinical studies, evaluation of left atrial (LA) function evolved from estimation of LA size on chest radiograph, electrocardiographic P wave abnormalities, LA diameter determined at fluoroscopy or by echocardiography, LA pressure recordings, blood flow velocity with Doppler echocardiography, and measurements of LA volume based on echocardiographic, cineangiographic, radionuclide, and magnetic resonance imaging techniques. The recent development of real-time two-dimensional echocardiographic acoustic quantification (AQ) suggests that LA dimensions can be measured instantaneously to provide online assessment of its systolic and diastolic functions. By means of AQ echocardiography and simultaneous recordings of LA pressure, the LA pressure-area relation can be obtained. LA pressure-area relation consisted of two loops: the A loop, representing the LA pump function, and the V loop, representing LA reservoir and passive emptying functions. The importance of LA function has been demonstrated in congestive heart failure, atrial fibrillation, hypertension, and ischemic heart disease and during pacing or dobutamine infusion.

Journal Article↗