Fragiskos I. Parthenakis

Left Ventricular Function and Cardiopulmonary Performance Following Surgical Treatment of Morbid Obesity

Background: It is well established that morbid obesity affects the respiratory system and the diastolic function of the heart. During exercise, cardiopulmonary reserve is exhausted because of augmented requirements, leading to a significant intolerance. A study was undertaken to investigate the influence of body weight loss on the characteristics of the left ventricle (LV) and on exercise capacity in obese patients before and 6 months following vertical banded gastroplasty (VBG). Methods: 16 morbidly obese individuals (BMI >40 kg/m2) scheduled for VBG were studied. A symptomlimited cardiopulmonary exercise test and a complete transthoracic echocardiogram were performed 1 day before operation and 6 months postoperatively (after the patients achieved a body weight loss of ≥ 20% of their pre-operative values). Results: Exercise duration increased significantly 6 months following surgery.The mean O2 consumption at peak exercise (peak VO2) and at the anaerobic threshold (VO2AT) was significantly higher after weight loss. 6 months after VBG the LV thickness decreased significantly. Regarding the diastolic indices, isovolumic relaxation time (IVRT) and early/late (E/A) velocity ratio, there was a significant improvement after weight loss. Simple linear regression analysis revealed that peak VO2 and VO2AT were significantly correlated with IVRT and E/A velocity ratio. Conclusions: Weight loss after VBG improves the cardiac diastolic function and this is associated with an improvement in cardiopulmonary exercise performance. Left ventricular filling variables could be considered among the most important determinants of exercise intolerance in obese individuals.

Amiodarone versus propafenone for conversion of chronic atrial fibrillation: results of a randomized, controlled study.

OBJECTIVES The purpose of this study was to investigate the efficacy and safety of amiodarone and propafenone in the conversion of chronic atrial fibrillation in a prospective, randomized, placebo-controlled study. BACKGROUND The effectiveness of amiodarone and propafenone in the treatment of patients with chronic atrial fibrillation has not been adequately studied. METHODS One hundred one patients (48 men, mean age 64 +/- 9 years) with atrial fibrillation lasting >3 weeks participated in the study. Thirty-four patients received amiodarone (300 mg intravenously over 1 h, followed by 20 mg/kg over the next 24 h plus 600 mg orally, in three doses, for 1 week, then 400 mg/day orally, for three weeks), 32 received propafenone (2 mg/kg intravenously over 15 min, followed by 10 mg/kg over 24 h and then 450 mg/day orally, for one month) and the remaining 35 served as control subjects. All patients received digoxin and anticoagulant treatment as indicated (International Normalized Ratio 2 to 3). RESULTS Conversion to sinus rhythm was achieved in 16 (47.05%) patients who received amiodarone, in 13 (40.62%) who received propafenone and in none of the control subjects (p < 0.001 for both groups vs. control subjects). Those who converted had smaller atria than those who did not and atrial fibrillation of shorter duration in both the amiodarone and propafenone groups. Treatment was discontinued in one patient of the propafenone group because of significant QRS widening. CONCLUSIONS Amiodarone and propafenone appear to be safe and equally effective in the termination of chronic atrial fibrillation. Left atrial diameter and arrhythmia duration are independent predictors of conversion.

Phasic coronary flow pattern and flow reserve in patients with left bundle branch block and normal coronary arteries.

OBJECTIVES The purpose of this study was to determine whether scintigraphic myocardial perfusion defects in patients with left bundle branch block (LBBB) and normal coronary arteries are related to abnormalities in coronary flow velocity pattern and/or coronary flow reserve. BACKGROUND Septal or anteroseptal defects on exercise myocardial perfusion scintigraphy are common in patients with LBBB and normal coronary arteries. METHODS Thirteen patients (7 men, age 61+/-8 years) with LBBB and normal coronary arteries underwent stress thallium-201 scintigraphy and cardiac catheterization. In all patients and in 11 control subjects coronary blood flow parameters were calculated from Doppler measurements of flow velocity in the left anterior descending coronary artery (LAD) before and after adenosine administration. RESULTS The time to maximum peak diastolic flow velocity was significantly longer both for the seven patients with (134+/-19 ms) and for the six without (136+/-7 ms) exercise perfusion defects than for controls (105+/-12 ms, p < 0.05), whereas the acceleration was slower (170+/-54, 186+/-42 and 279+/-96 cm/s2, respectively, p < 0.05). Coronary flow reserve in the patients with exercise perfusion defects (2.7+/-0.3) was significantly lower than in those without (3.7+/-0.5, p < 0.05) or in the control group (3.4+/-0.5, p < 0.05). CONCLUSIONS Patients with LBBB have an impairment of early diastolic blood flow in the LAD due to an increase in early diastolic compressive resistance resulting from delayed ventricular relaxation. Furthermore, exercise scintigraphic perfusion defects in these patients are associated with a reduced coronary flow reserve, indicating abnormalities of microvascular function in the same vascular territory.

MicroRNA-9 and microRNA-126 expression levels in patients with essential hypertension: potential markers of target-organ damage

MicroRNAs (miRs), as essential gene expression regulators, modulate cardiovascular development and disease and thus they are emerging as potential biomarkers and therapeutic targets in cardiovascular disease, including hypertension. We assessed the expression levels of the microRNAs miR-9 and miR-126 in 60 patients with untreated essential hypertension and 29 healthy individuals. All patients underwent two-dimensional echocardiography and 24-hour ambulatory blood pressure monitoring. MicroRNA expression levels in peripheral blood mononuclear cells were quantified by real-time reverse transcription polymerase chain reaction. Hypertensive patients showed significantly lower miR-9 (9.69 ± 1.56 vs 41.08 ± 6.06; P < .001) and miR-126 (3.88 ± 0.47 vs 8.96 ± 1.69; P < .001) expression levels compared with healthy controls. In hypertensive patients, miR-9 expression levels showed a significant positive correlation (r = 0.437; P < .001) with left ventricular mass index. Furthermore, both miR-9 (r = 0.312; P = .015) and miR-126 (r = 0.441; P < .001) expression levels in hypertensive patients showed significant positive correlations with the 24-hour mean pulse pressure. Our data reveal that miR-9 and miR-126 are closely related to essential hypertension in humans, as they show a distinct expression profile in hypertensive patients relative to healthy individuals, and they are associated with clinical prognostic indices of hypertensive target-organ damage in hypertensive patients. Thus, they may possibly represent potential biomarkers and candidate therapeutic targets in essential hypertension.

Absence of atherosclerotic lesions in the thoracic aorta indicates absence of significant coronary artery disease

Atherosclerotic lesions may be readily visualized in the thoracic aorta using transesophageal echocardiography. The absence of aortic plaque in the thoracic aorta rules out significant coronary artery obstruction whereas the existence of the former appears to be a sensitive and specific predictor of the latter.

Relation of autonomic modulation to recurrence of atrial fibrillation following cardioversion

The aim of this study was to investigate the time course of changes in autonomic nervous system activity in patients with long-standing atrial fibrillation (AF) following internal electrical conversion to sinus rhythm and to look for differences between patients who do and do not relapse. Time-domain indexes of heart rate variability were calculated from 24-hour Holter recordings on the day of conversion and 1 day and 1 month afterward for 22 patients with chronic (> 3 months) AF. Ten healthy subjects served as a control group. During the day of cardioversion the mean RR interval and its circadian variation differed significantly between controls and patients. The mean values of successive RR intervals that deviated by > 50% from the prior RR interval and the root-mean-square of successive RR interval differences--indexes of vagal modulation--were initially significantly higher in patients than in controls but showed a decrease (p < 0.05) by the second day (from 12.4 +/- 7% to 8.1 +/- 5% to 7.3 +/- 5% and from 49 +/- 9 to 39 +/- 12 to 41 +/- 11 ms, respectively) to levels similar to those of the controls (7.6 +/- 5% and 40 +/- 17 ms, respectively). Only these 2 indexes contained significant prognostic information about relapse: patients who later relapsed had higher initial values than those who did not, and these values remained high during the 2 days after conversion. In conclusion, this study provides data confirming that spontaneous chronic AF in humans results in a significant increase in vagal tone that is reversed with time after restoration of sinus rhythm. Persistently higher values of vagal tone are observed in patients who relapse, and are probably a predictor for recurrence.

Intravenous Propafenone Versus Intravenous Amiodarone in the Management of Atrial Fibrillation of Recent Onset: A Placebo-Controlled Study

The efficacy and safety of intravenous propafenone, amiodarone, or placebo were compared in the treatment of atrial fibrillation (AF) of recent onset (duration ≤ 48 hours). Methods: 143 patients (77 men, mean age 63 ± 12 years) were studied, of whom 46 received propafenone (2 mg/kg over 15 minutes followed by 10 mg/kg over the next 24 hours), 48 received amiodarone (300 mg intravenously over 1 hour, followed by 20 mg/kg over the next 24 hours, plus 1,800 mg/day orally, in 3 divided doses), and 49 received placebo (the equivalent amount of saline IV over 24 hours). Digoxin was administered to all patients who had not previously received it. Results: Conversion to normal sinus rhythm occurred in 36 of 46 patients (78.2%) receiving propafenone, in 40 of 48 patients (83.3%) receiving amiodarone, and in 27 of the 49 (55.10%) controls (P < 0.02, drug vs placebo, between drugs NS). The mean time to conversion was 2 ± 3 hours for propafenone, 7 ± 5 hours for amiodarone, and 13 ± 9 for placebo (P < 0.05). Patients who converted had smaller atria than those who did not (diameter: 42.7 ± 5 vs 47.2 ± 7 mm, P < 0.001 for all). Treatment was discontinued in one patient in the amiodarone group because of an allergic reaction and in two patients in the propafenone group because of excessive QRS widening. No side effects were observed in the placebo group. Conclusions: Both drugs tested intravenously were equally effective and safe for the rapid conversion of recent‐onset atrial fibrillation to sinus rhythm. However, propafenone offered the advantage of more rapid conversion than amiodarone.

AAIR Versus DDDR Pacing in Patients with Impaired Sinus Node Chronotropy: An Echocardiographic and Cardiopulmonary Study

The aim of this study was to compare AAIR and DDDR pacing at rest and during exercise. We studied 15 patients (10 men, age 65 ± 6 years) who had been paced for at least 3 months with activity sensor rate modulated dual chamber pacemakers. All had sick sinus syndrome (SSS) with impaired sinus node chronotropy. The patients underwent a resting echocardiographic evaluation of systolic and diastolic LV function at 60 beats/min during AAIR and DDDR pacing with an AV delay, which ensured complete ventricular activation capture. Cardiac output (CO) was also measured during pacing at 100 beats/min in both pacing modes. Subsequently, the oxygen consumption (VO2at) and VO2at pulse at the anaerobic threshold were measured during exercise in AAIR mode and in DDDR mode with an AV delay of 120 ms. The indices of diastolic function showed no significant differences between the two pacing modes, except for patients with a stimulus‐R interval > 220 ms, for whom the time velocity integral of LV filling and LV inflow time were significantly lower under AAI than under DDD pacing. At 60 beats/min, CO was higher under AAI than under DDD mode only when the stimulus‐R interval was below 220 ms. For stimulus‐R intervals longer than 220 ms, and also during pacing at 100 beats/min, the CO was higher in DDD mode. The stimulus‐R interval decreased in all patients during exercise. The time to anaerobic threshold, VO2at ond VO2at pulse showed no significant differences between the two pacing modes. Our results indicate that, at rest, although AAIR pacing does not improve diastolic function in patients with SSS, it maintains a higher CO than does DDDR pacing in cases where the stimulus‐R interval is not excessively prolonged. On exertion, the two pacing modes appear to be equally effective, at least in cases where the stimulus‐R interval decreases in AAIR mode.

Conversion of atrial fibrillation to sinus rhythm using acute intravenous procainamide infusion.

The efficacy and safety of intravenous procainamide in the conversion of atrial fibrillation was investigated. A total of 114 patients without severe heart failure were randomized to receive either intravenous procainamide (1 g over 30 minutes, followed by an infusion of 2 mg/min over 1 hour) or placebo in a double-blind trial. Digoxin (0.5 mg intravenously) was administered to all patients who had not previously been receiving digoxin. Treatment was considered successful if sinus rhythm was restored within 1 hour after starting the infusion. Conversion to sinus rhythm was achieved in 29 (50.9%) of the 57 patients treated with procainamide and in 16 (28.1%) of the 57 who received placebo (P ≊ 0.012). When the duration of the atrial fibrillation was ≤48 hours, conversion to sinus rhythm was achieved in 29 (69%) of the 42 patients receiving procainamide and in 16 (38.1%) of those receiving placebo (P ≊ 0.004). None of the patients with atrial fibrillation lasting ≤48 hours converted to sinus rhythm in either group. Another factor that played a role in the restoration of sinus rhythm was the size of the left atrium: the smaller the left atrium, the larger the success rate. The results of the study suggest that intravenous procainamide is an effective and safe means for the rapid termination of atrial fibrillation of recent onset and that its success rate is inversely related to the size of the left atrium. However, the drug is ineffective in the conversion of atrial fibrillation lasting more than 48 hours.

Proximal aortic stiffness is related to left ventricular function and exercise capacity in patients with dilated cardiomyopathy

AIMS Patients with heart failure (HF) show abnormal arterial stiffening. METHODS AND RESULTS We examined 60 patients (52.1 +/- 12, 8 years) with non-ischaemic dilated cardiomyopathy (NIDC), New York Heart Association II-III, in sinus rhythm, left ventricular ejection fraction 30.1 +/- 8.6%, and 44 normals. All subjects underwent an echocardiographic study and a cardiopulmonary exercise test. We evaluated the segmental proximal aorta (AO) pulse wave velocity (PWV) in the region of aortic arch with a new echo-method: from the suprasternal view, the distance between ascending and descending AO was measured with two-dimensional ultrasound, and the aortic flow wave transit time (TT) was measured with pulsed-wave Doppler. Pulse wave velocity was calculated as aortic distance/TT. Patients showed increased PWV (7.4 +/- 2.9 vs. 4.8 +/- 1.1 m/s, P < 0.001), compared with controls. Patients with advanced left ventricular (LV) (restrictive or pseudo-normal filling pattern) diastolic dysfunction showed increased PWV (8.6 +/- 2.6 vs. 6.6 +/- 2.9 m/s, P = 0.01) and reduced peak and predicted (for age, sex, and body mass) VO(2) (both P < 0.001), compared with those with mild diastolic dysfunction (delayed relaxation filling pattern). Pulse wave velocity was significantly correlated with the LV mass (r = 0.32, P = 0.01), the peak spectral tissue Doppler imaging systolic wave (r = -0.34, P = 0.006), the LV diastolic filling pattern (r = 0.42, P = 0.001), and the peak (r = -0.47, P < 0.001) and predicted VO(2) (r = -0.579, P < 0.001). CONCLUSION Patients with NIDC showed increased proximal aortic stiffness, which relates to LV systolic and diastolic function and exercise capacity. The echocardiographic assessment of the regional aorta PWV seems to be clinically important.