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Biomedical subjects

R Ricci

Publications and source records attributed to R Ricci.

At least 55 records · Page 3Linked to original sources
PubMed2001

Impact of consistent atrial pacing algorithm on premature atrial complexe number and paroxysmal atrial fibrillation recurrences in brady-tachy syndrome: a randomized prospective cross over study.

AIM OF THE STUDY: The Consistent Atrial Pacing (CAP) algorithm has been designed to achieve a high percentage of atrial pacing to suppress paroxysmal atrial fibrillation. The aim of our study was to compare the impact of DDDR+CAP versus DDDR pacing on paroxysmal atrial fibrillation recurrences and triggers in patients with Brady-Tachy Syndrome. METHODS: 61 patients, 23 M and 38 F, mean age 75+/-9 y, affected by Brady-Tachy Syndrome, implanted with a DDDR pacemaker, were randomized to DDDR or DDDR+CAP pacing with cross over of pacing modality after 1 month. RESULTS: 78 % of patients in DDDR pacing and 73 % in DDDR + CAP pacing (p=n.s.) were free from symptomatic paroxysmal atrial fibrillation recurrences. During DDDR+CAP pacing, the atrial pacing percentage increased from 77+/-29 % to 96+/-7 % (p<0.0001). Automatic mode switch episodes/day were 0.73+/-1.09 in DDDR and 0.79+/-1.14 (p=n.s.) in DDDR+CAP. In patients with less than 50 % of atrial pacing during DDDR, automaticmode switch episodes/day decreased during DDDR+CAP from 1.13+/-1.59 to 0.23+/-0.32 (p<0.05) and in patients with less than 90 % from 1.23+/-1.27 to 0.75+/-1.10 (p<0.001). The number of premature atrial complexes per day decreased during DDDR + CAP from 2665+/-4468 to 556+/-704 (p<0.02). CONCLUSION: CAP algorithm allowed continuous overdrive atrial pacing without major side effects. Triggers of paroxysmal atrial fibrillation induction, such as premature atrial complexes, were critically decreased. Paroxysmal atrial fibrillation episodes were reduced in patients with atrial pacing percentage lower than 90 % during DDDR pacing.

Aged↗
PubMed2001

Radiofrequency catheter ablation of idiopathic left ventricular outflow tract tachycardia: utility of intracardiac echocardiography.

INTRODUCTION: The site of origin of idiopathic ventricular tachycardia (VT) arising from the left ventricular outflow tract (LVOT) may be closely related to the aortic valve leaflets, and radiofrequency (RF) delivery potentially can damage them. Intracardiac echocardiography (ICE) can identify accurately the ablation electrode and anatomic landmarks, and contact with the endocardium can be easily assessed. The aim of this study was to define the utility and the accuracy of ICE in guiding RF ablation of idiopathic VT of the LVOT. METHODS AND RESULTS: Five consecutive patients (all men; mean age 20.4 years, range 16 to 25) symptomatic for idiopathic VT underwent RF ablation. A 9-French, in-sheath catheter with a 9-MHz ultrasound transducer was inserted through the femoral vein and positioned in the His-bundle region or right ventricular outflow tract to provide a clear view of the aortic root. Local earliest ventricular activation during tachycardia and pace mapping were used to identify the ablation site. Idiopathic VT was ablated successfully in all patients using a median of two RF pulses, delivered during tachycardia. High-resolution images of the aortic valve and ablation electrode were achievable in all cases. Direct vision of ablation electrode-endocardial contact in the outflow tract was assessed easily in all patients. CONCLUSION: Idiopathic VT of the LVOT can be treated successfully with RF ablation. ICE can accurately guide catheter ablation and identify anatomic landmarks, endocardial contact, and ablation electrode movement.

Adolescent↗
PubMed2001

Immediate and long-term atrial sensing stability in single-lead VDD pacing depends on right atrial dimensions.

AIMS: Single-pass VDD is a physiological stimulation mode which requires a single-lead with a floating dipole to detect the atrial signal. We investigated the impact of right heart dimensions on immediate and long-term atrial sensing stability in VDD systems to draw guidelines for optimal atrial sensitivity programming. METHODS: Forty-one patients (23 males, mean age 73 +/- 11 years) with II or III degree AV block and normal sinus node function received a Thera VDD Medtronic 8948 pulse generator with Medtronic 5032 lead. Atrial sensing was evaluated at pre-discharge and during 12-months follow-up in the supine and upright positions, during normal and forced breathing. Atrial sensing variability, quantified by a D value (mV), which represents the difference between the maximum and the minimum atrial electrogram amplitude obtained during the various activities, was analyzed and related to right heart dimensions measured at echocardiography. RESULTS: Long-term appropriate atrial sensing was obtained in 40/41 patients. P wave mean amplitude at pre-discharge, during every specific activity, was predictive of 12-month values. No atrial oversensing was observed. According to the right atrial dimension (RAD), patients with RAD > 38 mm had a sensing variability significantly higher than those with RAD < or = 34 mm (D=1 + 1 Vs D=0.4+/-0.5; P<0.05). A linear relationship between D and RAD dimensions was observed (r=0.47; P<0.005). According to the distance from the roof of the right atrium to the right ventricular apex (RAVD), patients with RAVD < 93 mm had D=1.1 +/- 1, while patients with RAVD > 93 mm had D=0.5 +/- 0.4; P<0.05); a inverse correlation between RAVD and D was highlighted (r=-0.43; P<0.01). Using a cluster analysis, the combination of RAD and RAVD identified a subgroup (RAD > 30 mm and RAVD < 80 mm) at high risk of loss of AV synchrony with 67% sensitivity and 80% specificity. Nevertheless, apart from heart dimensions, no patient showed an atrial signal amplitude lower than 0.3 mV. CONCLUSIONS: According to our data, in VDD single-lead systems the amplitude of the atrial signal is stable over time in every physical activity. High RAD and low RAVD values may select patients with poor atrial sensing stability. Anyway, taking into account that no atrial oversensing was observed, atrial sensitivity setting at the highest value should be recommended.

Aged↗
PubMed2001

Doppler myocardial imaging in patients with heart failure receiving biventricular pacing treatment.

BACKGROUND: In patients with heart failure, biventricular pacing (BIV) improves left ventricular (LV) performance by counteracting LV unsynchronized contraction caused by the presence of left bundle branch block (LBBB). However, no data are yet available on regional long-axis function in patients with LBBB or on BIV effectiveness in improving such a function in patients with heart failure and LBBB. METHODS AND RESULTS: We studied with standard 2D echocardiography and tissue Doppler imaging (TDI) 21 nonischemic patients in New York Heart Association (NYHA) class III-IV, with LBBB and QRS >/=120 ms, receiving BIV. To assess long-axis function, TDI qualitative analysis at the basal level of each LV wall was performed in M-mode color and pulsed wave Doppler modalities before and after BIV. By analysis of the interventricular septum, the inferior, posterior, lateral, and anterior walls, of 105 basal segments, the following electromechanical patterns were identified: normal (pattern I), mildly unsynchronized (pattern IIA), severely unsynchronized (pattern IIB), reversed early in systole (pattern IIIA), reversed late in systole (pattern IIIB), and reversed throughout all the systole (pattern IV). After BIV, (1) 49 (46.7%) of 105 segments showed unsynchronized contraction of the same degree as before; (2) 36 (34.3%) of 105 and 20 (19%) of 105 showed unsynchronized contraction of lesser and greater degree, respectively, than before; and (3) a preexcitation pattern was found in 11 (10.5%) of 105, but no segment with pattern IV was observed. According to TDI analysis, patients were divided into group 1 (10 of 21), with less severe LV asynchrony than before BIV, and group 2 (11 of 21), with no change or more severe LV asynchrony than before BIV. In group 1, (1) the LV ejection fraction increased significantly (P =.01); (2) the exercise tolerance, expressed as time and work capacity on the bicycle stress testing, increased significantly (P =.01, P =.003, respectively); (3) the 6-minute walked distance increased significantly (P =.01); and (4) the NYHA class decreased significantly (P =.003). In group 2, no significant differences were found either in LV ejection fraction, in NYHA class, or in exercise tolerance data (P = not significant for all). Conversely, the QRS narrowing was significant in both groups (P =.003 in group 1 and P =.01 in group 2). CONCLUSIONS: TDI is useful in assessing the severity of LV asynchrony in patients with LBBB with heart failure as well as in evaluating the pacing effects on long-axis function in these patients. BIV reduced unsynchronized and/or dyskinetic contraction in at least one third of the LV basal segments, whereas it induced preexcitation in approximately 10%. Such changes were responsible for better LV synchrony in approximately one half of patients. After BIV, LV performance improved significantly in patients with better LV synchrony evaluated by TDI, whereas the QRS narrowing was not predictive of this functional improvement.

Bundle-Branch Block↗
PubMed2001

Effect of early treatment with captopril and metoprolol singly and together on postinfarction left ventricular remodeling.

BACKGROUND: beta-Blockers improve clinical outcome after acute myocardial infarction (AMI), but few data are available on their effectiveness in preventing left ventricular remodeling. The aim of the study was to assess the relative effects of captopril, metoprolol, and their combination on left ventricular remodeling after uncomplicated AMI. METHODS: Two hundred fifty consecutive patients with a first AMI were randomly allocated to receive for 6 months captopril (up to 75 mg/d, group 1), metoprolol (up to 200 mg/d, group 2), or both (group 3) starting within 24 hours from symptom onset. Of these, 130 patients (group 1, 46; group 2, 47; group 3, 37) completed the study; all patients underwent 2-dimensional echocardiography at baseline and after 2 weeks and 3 and 6 months from AMI. RESULTS: At 6 months, in comparison with baseline values, left ventricular end-diastolic area index (LVEDI) significantly increased in group 3 (P =.013) and wall motion score index significantly decreased in group 1 (P =.038). At any follow-up evaluation, the covariance analysis showed significantly greater interval changes in LVEDI in group 3 than in group 1 (P =.0077 at 2 weeks, P =.0108 at 3 months, and P = 0.0155 at 6 months). No significant differences were observed between group 1 and group 2 and between group 2 and group 3. CONCLUSIONS: After uncomplicated first AMI, early and long-term treatment with captopril alone attenuates left ventricular remodeling better than its combination with metoprolol. In the head-to-head captopril versus metoprolol therapy strategy comparison, captopril alone seems more effective in reducing postinfarction enlargement, but a definite difference was not demonstrated.

Adrenergic beta-Antagonists↗
PubMed2001

Randomized crossover comparison of right atrial appendage pacing versus interatrial septum pacing for prevention of paroxysmal atrial fibrillation in patients with sinus bradycardia.

BACKGROUND: New atrial pacing techniques and overdrive pacing algorithms have been introduced to prevent atrial fibrillation. This study was designed to test the hypotheses that (1) interatrial septum pacing (IASP) at the triangle of Koch would be more effective than right atrial appendage pacing (RAAP) in preventing paroxysmal atrial fibrillation (PAF) in patients with sinus bradycardia and (2) an algorithm (CAP) designed to achieve constant atrial capture would increase the efficacy of rate-responsive atrial pacing. METHODS: We studied 46 patients with PAF and sinus bradycardia implanted with a DDD(R) (Medtronic Thera) pacemaker. Twenty-four patients (6.0 +/- 10.1 PAF episodes/month within 3 months before study) were randomized to RAAP and 22 patients (5.4 +/- 7.1, not significant) to IASP. Within each arm 2 randomized crossover periods of CAP-OFF and CAP-ON function were programed. RESULTS: The PAF episodes per month significantly decreased in the RAAP (CAP-OFF: 2.1 +/- 4.2, P <.05; CAP-ON: 1.9 +/- 3.8, P <.05) and in the IASP group (CAP-OFF: 0.2 +/- 0.5, P <.05; CAP-ON: 0.2 +/- 0.5, P <.05). Values were significantly lower in the IASP group than in the RAAP group in both CAP-OFF (0.2 +/- 0.5 vs 2.1 +/- 4.2, P <.05) and CAP-ON (0.2 +/- 0.5 vs 1.9 +/- 3.8, P <.05) conditions. PAF burden was significantly lower in the IASP than in the RAAP group in CAP-OFF (47 +/- 84 min/d vs 140 +/- 217, P <.05) and in CAP-ON (41 +/- 72 vs 193 +/- 266, P <.05) conditions. No differences were observed within each arm in PAF burden between the 2 crossover CAP programing periods. CONCLUSIONS: Rate-adaptive IASP at the triangle of Koch is more effective than RAAP in preventing PAF in patients with sinus bradycardia. In our sample of patients no additional clinical benefit is furnished by the CAP algorithm.

Aged↗
PubMed2001

Dissolution test for silymarin tablets and capsules.

Silybine (SBN), isosilybine (ISBN), silycristine (SCN), silydianine (SDN), and taxifoline (TXF) are the main active flavonoids commonly found in the dried fruits of Silybum marianum, Gaertner (Compositae). Concentrations of these compounds, except TXF, are usually expressed together as silymarin content. This paper describes a simple dissolution test developed to estimate silymarin (Sl) in pharmaceutical formulations. Five commercial products were tested using this new method (including tablets, sugar tablets, and capsules): two from Argentina, one from Brazil, one from Spain, and one from Italy. Results demonstrated that, provided the dosage form disintegrates, amounts dissolved range from 50 to 90% of the labeled value. Products were analyzed by high performance liquid chromatography (HPLC) and UV spectrophotometry.

Antioxidants↗
PubMed2001

Kaposi's sarcoma associated with previous human herpesvirus 8 infection in kidney transplant recipients.

This study investigates the prevalence of human herpesvirus 8 (HHV-8) infection in kidney transplant patients, evaluating the risk of HHV-8 transmission via transplantation and the association between pre- and posttransplantation HHV-8 infection and the subsequent development of Kaposi's sarcoma (KS). Immunofluorescence and an enzyme immunoassay were used to determine HHV-8 seroprevalence in 175 patients awaiting kidney transplantation and 215 controls who were attending our clinic for other reasons. All patients in the study came from central or southern Italy. Seroprevalence was similar in both groups (14.8 versus 14.9%), with no significant difference between the rates for male and female patients. Of the 175 patients, 100 were tested for anti-HHV-8 antibodies at various times during follow-up. During follow-up, seroprevalence increased from 12% on the date of transplantation to 26%. This increase was paralleled by an age-related increase in seroprevalence in the control group. During follow-up from 3 months to 10 years after transplantation, KS was diagnosed in seven patients (4.0%). Six of these patients were positive for HHV-8 prior to transplantation. Overall, 23.0% of patients who were HHV-8 positive before transplantation developed KS, whereas only 0.7% of seronegative patients developed the disease (relative risk, 34.4; 95% confidence interval, 4.31 to 274.0). This finding suggests that the key risk factor for KS is infection prior to transplantation and that antibody detection in patients awaiting transplantation could be useful in identifying patients at high risk for KS. In patients from geographic areas with a high prevalence of HHV-8, serological tests on donors may be less important.

Adult↗
PubMed2001

Glycosaminoglycans: urinary excretion in children with myelomeningocele.

BACKGROUND: The main consequences of neurogenic bladder dysfunction are renal damage related to high intravesical pressure, vesicoureteral reflux (VUR) and urinary tract infections (UTIs). Neurologic impairment, UTIs and VUR are known to be linked with a potential for renal scarring. Of paramount importance as predisposing conditions for UTIs in neurogenic bladder are poor bladder drainage and detrusor-sphincter dyssynergy which cause further abnormalities on the internal bladder surface and, consequently, a bladder wall rich in glycosaminoglycans (GAGs). MATERIALS AND METHODS: The aim of this study is to investigate the correlation between GAG excretion and bladder wall degeneration in 43 patients affected by spina bifida (SB) and 40 healthy age-matched control children. RESULTS: The amounts of GAGs excreted vary greatly in SB patients aged from 0 to 5 years, and values are comparable to those observed in normal controls. They are significantly higher in children over 5 years of age. CONCLUSION: The increased excretion of GAGs in older SB patients is an important parameter in the evaluation of the physiopathological condition of the bladder wall and hence may be considered a possible marker for monitoring the beginning of bladder damage.

Child↗
PubMed2001

Electrotherapeutic management of patients with heart failure.

Heart failure is associated with poor long term survival due to progressive refractory heart dysfunction and sudden cardiac death. Cardiac resynchronization through atrio-biventricular pacing has been introduced to treat patients affected by drug-refractory heart failure with desynchronized ventricular activation, as for complete left bundle branch block. The technique is aimed to overcome interventricular and intraventricular conduction delays leading to ventricular dysynchrony, paradoxical septal wall motion, presystolic mitral regurgitation and reduced diastolic filling times. Short term studies demonstrated that biventricular pacing (and perhaps left ventricular pacing alone) may improve both systolic and diastolic function. Initial studies in patients receiving long term pacing consistently showed significant QRS shortening associated with improvement in symptoms, left ventricular ejection fraction, exercise tolerance, quality of life and New York Heart Association functional class. As far as sudden cardiac death prevention in heart failure is concerned, implantable cardioverter defibrillator (ICD) implantation has been demonstrated to be the most effective therapy in patients with prior cardiac arrest due to ventricular fibrillation or poorly tolerated ventricular tachycardia. Low left ventricular ejection fraction, unsustained ventricular tachycardia and inducibility at electrophysiological study also may identify high risk patients requiring ICD implantation. Further studies are needed to evaluate the effect of cardiac resynchronization on hard end-points, such as survival and long term clinical outcome, and to upgrade risk stratification criteria to be used in selection of candidates for ICD implantation.

Clinical Trials as Topic↗
PubMed2001

Paroxysmal atrial fibrillation in patients paced for atrioventricular block. Comparison between DDD and VDD single-lead pacing system.

BACKGROUND: Paroxysmal atrial tachyarrhythmias have been frequently detected in patients paced for atrioventricular block. However, it is not yet clear which is the actual incidence of such arrhythmias and if they were preexisting but not recognized, or if they could be related to the device. METHODS: One hundred and forty-five patients with a diagnosis of second or third degree atrioventricular block were enrolled into the study. One hundred and twenty-four received a pacemaker Medtronic Thera DDD and 21 a Medtronic Thera VDD. High rate atrial episodes were evaluated for 3 months after enrollment. Atrial electrograms documenting paroxysmal atrial fibrillation (AF) were stored and programming of atrial sensitivity and pacemaker diagnostics was very strict in order to exclude short and false positive AF episodes. RESULTS: Thirty-six patients (35%) in the DDD group and 8 (42%) in the VDD group presented with AF (p = NS). The mean number o

Aged↗
PubMed2001

[Indications and potential benefits of implantable automatic defibrillator endowed with biventricular pacing].

Heart failure (HF) is associated with a poor long-term survival due to progressive refractory heart dysfunction and sudden cardiac death. Cardiac resynchronization through three-chambered atriobiventricular pacing has been introduced to treat patients with drug-refractory HF and unsynchronized ventricular activation due to left bundle branch block (LBBB). The technique is aimed to overcome inter- and intraventricular conduction delays leading to a ventricular dyssynchrony, characterized by paradoxical septal wall motion, presystolic mitral regurgitation, and reduction in diastolic filling times. Acute studies demonstrated that biventricular pacing (and maybe left ventricular pacing alone) may improve both systolic and diastolic function. First studies on chronically paced patients consistently showed that the QRS shortening was associated with a significant improvement in symptoms, NYHA functional class, left ventricular ejection fraction (LVEF), exercise tolerance, and quality of life. As far as sudden cardiac death prevention in HF is concerned, the implantable cardioverter-defibrillator (ICD) has been demonstrated to be the most effective therapy in patients with prior cardiac arrest due to ventricular fibrillation or poorly tolerated ventricular tachycardia. Low LVEF, unsustained ventricular tachycardia and inducibility at electrophysiological study also may identify high risk patients requiring ICD implantation. Further studies are needed in evaluating the impact of cardiac resynchronization on hard endpoints, such as survival and long-term clinical outcome, as well as in upgrading risk stratification criteria to be used in candidate selection to ICD implantation. However, HF patients with prior cardiac arrest and LBBB should be considered as the optimal candidates to the "ICD implantation combined with biventricular pacing". Conversely, HF patients with LBBB, but without cardiac arrest, could be considered for "biventricular pacing combined with an ICD". The selection criteria for this novel non-pharmacological therapy still have to be defined. The authors emphasize the main indication to ICD implantation combined with biventricular pacing, i.e. HF patients with prior cardiac arrest and LBBB; controversially, while they discuss the other indications to biventricular pacing combined with an ICD.

Bundle-Branch Block↗
PubMed2001

Establishment of a deer mouse (Peromyscus maniculatus rufinus) breeding colony from wild-caught founders: comparison of reproductive performance of wild-caught and laboratory-reared pairs.

The deer mouse (Peromyscus maniculatus) is a natural reservoir for several human pathogens, but little is known about the mechanisms by which such pathogens are maintained in nature. As a first step toward developing a colony of deer mice that were permissive for infection with Sin Nombre (SN) hantavirus, we collected 68 wild P. maniculatus rufinus from central New Mexico. Mice from this cohort were used to establish 26 breeding pairs, of which 85% were fertile. In subsequent generations, fertility decreased slightly to 73% (N = 59) in laboratory-reared F1 and F2 pairs. Wild-caught females delivered 7.2 litters on average (range, 1 to 18), whereas laboratory-reared pairs delivered 5.5 (range, 1 to 13). The average time between pairing and first litter was 106 days for wild-caught animals, whereas that for laboratory-reared pairs was 71 days. None of the pairs displayed a seasonal breeding preference. Cannibalistic behavior increased from 5% in founders to 26% in laboratory-reared pairs. Mean litter size for wild-caught females was 4.3, whereas that for laboratory-reared dams was 4. Founding animals have been maintained in captivity for longer than 2 years, with only 2 deaths (4.8%). Our colony is competent for infection with SN virus. Thus, it should be useful for testing of models for maintenance of SN virus in wild rodents, and other aspects of the virus-host relationship.

Animal Husbandry↗
PubMed2000

Experimental infection model for Sin Nombre hantavirus in the deer mouse (Peromyscus maniculatus).

The relationship between hantaviruses and their reservoir hosts is not well understood. We successfully passaged a mouse-adapted strain of Sin Nombre virus from deer mice (Peromyscus maniculatus) by i.m. inoculation of 4- to 6-wk-old deer mouse pups. After inoculation with 5 ID(50), antibodies to the nucleocapsid (N) antigen first became detectable at 14 d whereas neutralizing antibodies were detectable by 7 d. Viral N antigen first began to appear in heart, lung, liver, spleen, and/or kidney by 7 d, whereas viral RNA was present in those tissues as well as in thymus, salivary gland, intestine, white fat, and brown fat. By 14 d nearly all tissues examined displayed both viral RNA and N antigen. We noted no consistent histopathologic changes associated with infection, even when RNA load was high. Viral RNA titers peaked on 21 d in most tissues, then began to decline by 28 d. Infection persisted for at least 90 d. The RNA titers were highest in heart, lung, and brown fat. Deer mice can be experimentally infected with Sin Nombre virus, which now allows provocative examination of the virus-host relationship. The prominent involvement of heart, lung, and brown fat suggests that these sites may be important tissues for early virus replication or for maintenance of the virus in nature.

Animals↗
PubMed2000

Quercetin inhibits p21-RAS expression in human colon cancer cell lines and in primary colorectal tumors.

Immunocytochemical studies have revealed that 10 microM quercetin reduced the steady state levels of p21-ras proteins in both colon cancer cell lines and primary colorectal tumors. These findings were confirmed by Western blot and flow cytometric analysis showing that the inhibition of p21-ras expression by quercetin was time- and concentration-dependent. Twenty-four-hour treatment with 10 microM quercetin reduced p21-ras levels to about 50% of control values. Quercetin was similarly effective in inhibiting the expression of K-, H-, and N-ras proteins. Moreover, the effect of quercetin on ras oncogene expression was not dependent on the cell cycle position of colon cancer cells and appeared to be specific and not merely a consequence of overall inhibition of protein synthesis. Northern blot analysis revealed that quercetin produced in colon cancer cells an early (30 min) reduction of the steady state levels of K-, H-, and N-ras mRNAs. This reduction was also present after 6 hr of flavonoid treatment. These effects of quercetin suggest a possible chemopreventive role for this compound in colorectal carcinogenesis.

Anticarcinogenic Agents↗