Preserved Vasodilator Response to Acetylcholine in Atherosclerotic Coronary Arteries Before and After PTCA

The vascular response to local administration of acetylcholine is used, clinically, to assess endothelial function in vivo. However, whether this response predominantly reflects the functional state of the vascular endothelium, or rather results from smooth muscle reactivity per se is not clear. In 15 patients with chronic stable angina and angiographically significant coronary disease, we studied the effects of increasing doses of intracoronary acetylcholine (5, 10, 30, 50, and 80 μg) and nitroglycerin (200 μg) on coronary vascular tone. In three patients the protocol was perfrnned at the time of diagnostic coronary angiographv and 7 and 24 hours after angioplasty. The remaining five underwent acetylcholine administration before and after percutaneous transluminl coronary angioplasty (PTCA). We quantitatively assessed the diameter of 54 coronary arterial segments; 12 stenotic segments, 13 post-PICA segments with residual irregularities, 18 reference segments of the ranee arteries taken proximal to the stenosis or to the dilatation site, and II remote segments ofnonstenotic vessels. They all showed a bimodal response to acetylcholine. At the lowest concentration (5 μg) the agent invariably caused dilatation (9.22 ± 6.55%), which was not significantly different in the various segments and was always less than that induced by nitroglycerin (24.56 ± 12.82%, P < 0.0001). At the highest doses (50 or 80 μg) acetylcholine always induced vasoconstriction, which was significantly more pronounced in the post-PTCA (-31.54 ± 10.65%) and stenotic segments (-23.08 ± 11.88%) than in the reference and remote segments (respectively, -14.88 + 7.63% and - 18.67 + 8.37%, P < 0.05). We conclude that: (l) some degree of endothelial dependent vasodilatation is preserved even in the presence of atheroma and intimal injury induced by angioplasty; (2) atheroma and especially acute intimal injury augment the vasoconstrictor response to high dose acetylcholine, the effect being most probably mediated by primary smooth muscle supersensivity: (3) since acetylcholine has direct and endothelium-mediated vasoactive effects, this agent may not be the ideal one for testing endothelial integrity. (J Interven Cardiol 1994; 7:57–64)     

Mapping of Atrial Tachycardia by Remote Magnetic Navigation in Postoperative Patients With Congenital Heart Disease

Remote Magnetic Mapping in Congenital Heart Disease . Objectives: The purpose of this study was to investigate if remote magnetic navigation (RMN) offers a reduction of fluoroscopy time when used for atrial tachycardia (AT) mapping in a spectrum of patients with congenital heart disease (CHD) after “simple” or “complex” atrial surgery. Background: Data about AT mapping using RMN in larger populations of patients with CHD are scarce. Methods: RMN in combination with electroanatomic mapping was used for AT mapping in 22 patients. According to anatomic complexity, patients were classified into 3 groups: Group 1: patients after minor atrial surgery (n = 7); Group 2: patients after the Fontan operation (n = 9); and group 3: patients after the Senning/Mustard operation (n = 6). Results: Atrial mapping with a nonirrigated tip RMN catheter was completed successfully in all patients. In Group 1 no significant reduction in fluoroscopy time was noticed over time (mean fluoroscopy time 7.9 minutes). In the 15 patients of group 2 and group 3 with complex CHD, the fluoroscopy time for mapping in the last 9 patients (6.4 ± 2.8 minutes) was significantly shorter than in the first 6 patients (29.7 ± 10.5 minutes, P < 0.0001). Acutely successful ablation was achieved in 21 of 22 patients (97%) using the RMN catheter (n = 3) or a conventional catheter (n = 18) without procedural complications. Conclusions: RMN for AT mapping in patients with complex atrial anatomy leads to a significant reduction of fluoroscopy time. (J Cardiovasc Electrophysiol, Vol. pp. 751‐759, July 2010)     

Monitoring Intrathoracic Impedance with an Implantable Defibrillator Reduces Hospitalizations in Patients with Heart Failure

Purpose: Some implantable cardioverter‐defibrillators (ICDs) are now able to monitor intrathoracic impedance. The aim of the study was to describe the use of such monitoring in clinical practice and to evaluate the clinical impact of the fluid accumulation alert feature of these ICDs. Methods and Results: Five hundred thirty‐two heart failure (HF) patients implanted with these ICDs were followed up for 11 ± 7 months. A clinical event (CE) was deemed to have occurred if it resulted in hospitalization or milder manifestations of HF deterioration. Three hundred sixty‐two acute decreases in intrathoracic impedance (Z events) occurred in 230 patients. Of these episodes, 171 (47%) were associated with a CE within 2 weeks of the Z event. In another 71 (20%) Z events, drug therapy was adjusted despite the absence of overt signs of clinical deterioration. The rate of unexplained Z events was 0.25 per patient‐year and 25 hospitalizations were not associated with Z events. The audible alert was disabled in a group of 102 patients (OFF group). HF hospitalizations occurred in 29 (7%) patients in the ON group and 20 (20%, P < 0.001) patients in the OFF group. The rate of combined cardiac death and HF hospitalization was lower in patients with Alert ON (log‐rank test, P = 0.007). Conclusions: The ICD reliably detected CE and yielded low rates of unexplained and undetected events. The alert capability seemed to reduce the number of HF hospitalizations by allowing timely detection and therapeutic intervention.