Olivier Gurné

Effective prevention of atrial fibrillation by continuous atrial overdrive pacing after coronary artery bypass surgery.

OBJECTIVES The present study was aimed to evaluate the efficacy of a specific algorithm with continuous atrial dynamic overdrive pacing to prevent atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery. BACKGROUND Atrial fibrillation occurs in 30% to 40% of patients after cardiac surgery with a peak incidence on the second day. It still represents a challenge for postoperative prevention and treatment and may have medical and cost implications. METHODS Ninety-six consecutive patients undergoing CABG for severe coronary artery disease and in sinus rhythm without antiarrhythmic therapy on the second postoperative day were randomized to have or not 24 h of atrial pacing through temporary epicardial wires using a permanent dynamic overdrive algorithm. Holter ECGs recorded the same day in both groups were analyzed to detect AF occurrence. RESULTS No difference was observed in baseline data between the two study groups, particularly for age, male gender, history of AF, ventricular function, severity of coronary artery disease, preoperative beta-adrenergic blocking agent therapy or P-wave duration. The incidence of AF was significantly lower (p = 0.036) in the paced group (10%) compared with control subjects (27%). Multivariate analysis showed AF incidence to increase with age (p = 0.051) but not in patients with pacing (p = 0.078). It decreased with a better left ventricular ejection fraction only in conjunction with atrial pacing (p = 0.018). CONCLUSIONS We conclude that continuous atrial pacing with an algorithm for dynamic overdrive reduces significantly incidence of AF the second day after CABG surgery, particularly in patients with preserved left ventricular function.

Tako-tsubo syndrome following nortriptyline overdose

Background. Tako-tsubo syndrome (TTS) refers to the apical ballooning of the left ventricle observed when angiographic ventriculography is performed in patients presenting with electrocardiographic changes suggestive of acute coronary syndrome (new transient ST-segment deviation (>0.05 mV) or T-wave inversion (>0.2 mV)), mild elevation of cardiac markers, but normal coronary arteries at the angiogram. Case report. A 54-year-old woman developed the characteristic features of TTS 44 hours following nortriptyline overdose. The admission ECG showed increased QRS duration rapidly reversible after sodium bicarbonate infusion. There was a minimal increase in troponin I level. The ECG performed at the time of chest pain revealed deeply negative T waves in leads I, II, III, aVF, V1 to V6 and remained abnormal at 5 weeks follow-up. In contrast, a complete recovery of left ventricular function was observed within one week. Discussion. The pathophysiology of TTS, a variant of myocardial stunning, is still incompletely understood but could be related to sympathetic overstimulation. The possibility of TTS following toxic exposure is discussed.

Digital angiography: an open-system dedicated to left ventricular function studies

The authors describe an efficient procedure for analyzing left-ventricular function (LV) parameters of patients undergoing a cardiac catheterization. Adequate assessment of LV systolic and diastolic function requires the simultaneous acquisition of volume pressure and wall thickness at a sampling rate of at least 50 per second. As most commercially available systems do not offer this performance, the authors incorporated several improvements in the digital vascular imaging (DVI) system and analytical processing unit (APU) of Philips. Complete processing of simultaneous LV geometry and pressure recordings is described. The procedure for deriving and retrieving ventricular data is emphasized.<<ETX>>

Endothelium-dependent and endothelium-independent vasodilator response of left and right internal mammary and internal thoracic arteries used as a composite Y-graft §

OBJECTIVE The manner in which a blood vessel is for used as a coronary graft may be important in maintaining a viable and functional endothelial lining. Composite internal thoracic arteries (ITAs) in a Y-graft configuration are characterized by the connection of an in situ left ITA with preserved innervation and lymphatics and of a free semi-skeletonized right ITA. METHODS To determine whether endothelial function differs between left and right ITA segments in a Y-graft configuration, 11 patients were studied 3 years after surgery. The endothelium-dependent vasodilator substance P was selectively infused (1.4-22.4 pmol min⁻¹ in doubling dose increments) in the ostium of ITA Y-grafts. A maximal endothelium-independent vasodilatory response was then obtained by intragraft infusion of 2mg isosorbide dinitrate (ISDN). Biplane angiograms obtained at 3-min intervals using an automated contrast injection system with fixed preset volume and pressure parameters were analyzed off-line using a quantitative analysis system (CAAS, Pie Medical). RESULTS A similar dose-dependent vasodilatory response to substance P was observed in the left and in the right ITA. No difference in maximal endothelium-dependent response to substance P (7.4 ± 4.3% in the left ITA and 8.1 ± 5.3% in the right ITA) or in maximal endothelium-independent response to ISDN (12.2 ± 4.4% in the left ITA and 10.6 ± 8.1% in the right ITA) was observed. CONCLUSIONS The endothelium-dependent and the endothelium-independent vasodilator capacity of the two branches of a Y-graft ITA configuration appear similar 3 years after bypass surgery. This suggests that the preservation of the ITA pedicle does not significantly affect basal vasomotor tone, long-term endothelial function, or vasodilator reserve.

Curvature analysis of ventriculograms: how useful is it to assess progression of left ventricular remodeling and dysfunction

Angiographic data of 23 patients are used to assess the progression of left ventricular enlargement by a regional curvature analysis. The derived information is correlated with the results obtained by a classical method of ventricular function study to improve the understanding of complex changes in regional ventricular wall motion. The methodology to quantify curvatures from right anterior oblique left ventriculograms is also emphasized. It is shown that in its present form, the procedure is useless, as it does not yield reliable information. Nevertheless, the fact that this analysis points toward the apex of the ventricle as one of the key areas during progressive dilatation suggests that important physiologic information could be obtained in an adequate mathematical description of this area.<<ETX>>