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Biomedical subjects

G F Percoco

Publications and source records attributed to G F Percoco.

12 recordsLinked to original sources
PubMed2004

Oxidative stress during myocardial ischaemia and heart failure.

Oxidative stress is a condition in which oxidant metabolites exert their toxic effect because of an increased production or an altered cellular mechanism of protection. The heart needs oxygen avidly and, although it has powerful defence mechanisms, it is susceptible to oxidative stress, which occurs, for instance, during post-ischaemic reperfusion. Ischaemia causes alterations in the defence mechanisms against oxygen free radicals, mainly a reduction in the activity of mitochondrial superoxide dismutase and a depauperation of tissue content of reduced glutathione. At the same time, production of oxygen free radicals increases in the mitochondria and leukocytes and toxic oxygen metabolite production is exacerbated by re-admission of oxygen during reperfusion. Oxidative stress, in turn, causes oxidation of thiol groups and lipid peroxidation leading first to reversible damage, and eventually to necrosis. In man, there is evidence of oxidative stress (determined by release of oxidised glutathione in the coronary sinus) during surgical reperfusion of the whole heart, or after thrombolysis, and it is related to transient left ventricular dysfunction or stunning. Data on oxidative stress in the failing heart are scant. It is not clear whether the defence mechanisms of the myocyte are altered or whether the production of oxygen free radicals is increased, or both. Recent data have shown a close link between oxidative stress and apoptosis. Relevant to heart failure is the finding that tumour necrosis factor, which is found increased in failing patients, induces a rapid rise in intracellular reactive oxygen intermediates and apoptosis. This series of events is not confined to the myocytes, but occurs also at the level of endothelium, where tumour necrosis factor causes expression of inducible nitric oxide synthase, production of the reactive radical nitric oxide, oxidative stress and apoptosis. It is therefore, possible that the immunological response to heart failure results in endothelial and myocyte dysfunction through oxidative stress mediated apoptosis. Clarification of these mechanisms may lead to novel therapeutic strategies.

Animals↗
PubMed1994

Long-term reliability of single lead atrial synchronous pacing systems using closely spaced atrial dipoles: five-year experience.

To assess the long-term capability of single atrioventricular (AV) lead VDD pacing systems using close atrial dipoles to assure reliable atrial guided pacing, the safety and efficacy of 86 VDD units implanted in 73 patients at a single center since November 1988 was reviewed. All patients suffered from advanced AV block with normal sinoatrial function. Sixty five patients received a LEM/CCS Twinal 30/30S system, four patients received a Vitatron-Saphir system, and four patients received a Medtronic Thera VDR 8348 system. All patients underwent provocative tests in search of myopotential interference, and Holter recordings; in a group of patients who underwent pacemaker replacement a comparison was made between implant and replacement measurements. The mean follow-up duration was 27.3 months. A high percentage of successfully VDD paced patients and a low incidence of pacemaker malfunction, regularly solved by pacemaker reprogramming, was reported. Atrial signal amplitudes comparable to those measured at implant were found at replacement in all patients. These data support the long-term reliability of single AV lead VDD pacing systems with closely spaced atrial dipoles, as well as stable atrial sensing by floating bipolar atrial electrodes and effective atrial synchronous ventricular pacing over time.

Aged↗
PubMed1994

AV delay optimization and management of DDD paced patients with dilated cardiomyopathy.

Ten DDD paced patients, suffering from dilated cardiomyopathy in the NYHA functional classes III or IV were studied by means of Doppler echocardiography at different programmed values of atrioventricular (AV) delay (200, 150, 120, 100, and 80 msec). The following variables were evaluated: LV diameter, ejection fraction, mitral and aortic flow velocity integrals, and stroke volume. During VDD pacing, a resting AV delay associated with the best diastolic filling and systolic function was identified and programmed individually. Shortening of the AV delay to about 100 msec was associated with a gradual and progressive improvement. Further decrease caused an impairment of systolic function. The patients were clinically and hemodynamically reevaluated after 2 months of follow-up. A reduction of NYHA class and an improvement of LV function were consistently found. The reported data suggest that programming of an optimal AV delay may improve myocardial function in DDD paced patients with congestive heart failure. This result may be the consequence of an optimization of left ventricular filling and a better use of the Frank-Starling law.

Aged↗
PubMed1992

Italian multicenter study on a single lead VDD pacing system using a narrow atrial dipole spacing.

Since November 1988, 514 patients with advanced atrioventricular (AV) block and normal sinoatrial function have received the single lead VDD pacing system Twinal 30 Lem/CCS in 30 Italian centers. At implantation, particular attention was paid to the correct positioning of the atrial dipole in the mid- to mid-high right atrium and to the atrial electrogram characteristics. The follow-up included a chest X ray, to be performed before discharge of the patient from the hospital, telemetric evaluations of the endoatrial potential, provocative tests for interferences by myopotentials, 24-hour ambulatory EGG recordings, and where possible, exercise stress tests. The mean follow-up duration was 15.2 months, ranging from 1 to 42 months. A very low percentage of chronic atrial fibrillation, loss of atrial sensing, and system replacement was reported, most of the patients (93.5%) being paced in VDD mode. All investigations indicated an excellent overall system performance, stable AV synchrony, and infrequent myopotential interference, and a low complication rate throughout the follow-up period.

Aged↗
PubMed1991

Role of sinus node artery disease in sick sinus syndrome in inferior wall acute myocardial infarction.

This study was undertaken to evaluate a possible role of sinus node (SN) artery disease in the pathogenesis of sick sinus syndrome (SSS) in patients with an inferior wall acute myocardial infarction (AMI). Coronary angiography and electrophysiologic studies of the SN, both in the basal state and after pharmacologic autonomic blockade, were performed in 23 study patients (mean age 60 years) with SSS and a previous inferior wall AMI and in another 23 control patients (mean age 57 years) with normal sinus rate and a previous inferior AMI. Stenosis of the SN artery (or that proximal to its origin) greater than 50% was present in 13 study patients (56%) and in 8 control patients (34%) (p less than 0.05). In the study group, the intrinsic heart rate was abnormal in 5 of the 6 patients (83%) with severe SN artery stenosis (greater than or equal to 75% narrowing), in 3 of the 7 (43%) with moderate stenosis (50 to 75% narrowing) and in 3 of the 10 (30%) with insignificant stenosis (less than 50% narrowing). In the study group, the correlation between the SN measures (heart rate, corrected SN recovery time and sinoatrial conduction time) and the severity of SN artery stenosis was good after autonomic blockade (r between 0.59 and 0.64) and poor in the basal state. These data provide evidence for a role of SN artery disease in the pathogenesis of SSS in patients with an inferior wall AMI.

Angiography↗
PubMed1990

AV delay and exercise stress tests: behavior in normal subjects.

In normal subjects the atrioventricular (AV) conduction is accelerated during exertion. The relationship between heart rate and AV delay is usually described as "linear". Looking at the increasing importance given to an appropriate AV synchrony in permanent dual chamber and P synchronous pacing we present the results of an investigation performed to study the correlation between AV conduction time and heart rate under stress conditions, and disclose some new aspects of this matter, which will possibly be useful for a further improvement of pacemaker technology.

Adult↗
PubMed1990

A new single lead VDD pacing system.

In 24 patients with advanced heart block and normal sinus node function, a new single lead VDD pacing system was implanted. At implantation, the endoatrial, bipolar electrogram was recorded in all patients. The lead position was checked by means of chest X-ray. At discharge and after 1, 3, and 6 months, testing for myopotential inhibition, telemetric evaluation of the endoatrial potential, and Holter recordings were made. After discharge, 18 patients performed two cardiopulmonary exercise tests at two different rate-matched AV intervals. All investigations showed good AV synchrony and a lack of interferences by myopotentials. The maximum rate-matched AV interval provided a significantly improved exercise capacity, which was more evident in patients with signs of myocardial failure.

Aged↗
PubMed1981

[Value and limits of echocardiography of the acute or previous myocardial infarction. Mono- and bi-dimensional study (author's transl)].

81 subjects with acute or previous myocardial infarction were studied in order to assess the relations between ecg location and diskinetic zones as seen on the echocardiogram; another purposes of the work was to establish if serial echocardiographic measurements would be useful for prognostic purposes. The obtained results were the following: 1) there is a good correlation between ecg location of anterior infarction and diskinetic or ipokinetic zones if on the echocardiographic pattern were simultaneously present the following echocardiographic findings: lessened systolic escursion + lessened systolic thickening + enhanced left ventricular diastolic dimension (LVDD); 2) in the group of posterior and inferior infarctions is observed either an ipokinetic left ventricular posterior wall either an ipokinetic septum; 3) left ventricle diastolic dimension (LVDD) was greater and the motion of the septum was less frequently paradoxical in previous infarction than in acute infarction; 4) there was a good correlation in anterior acute infarction among M-mode echo-patterns which indicate both progressive dilatation of the left ventricle and an abnormal septum movement and the appearance of congestive failure, shock and intrahospital mortality; 5) the aneurysms localized in apical section of the ventricles could be missed by M-mode studies and therefore when this complication is suspected bidimensional investigations are more indicated.

Adult↗