Biomedical subjects

Angel R Leon

Publications and source records attributed to Angel R Leon.

12 recordsLinked to original sources

PubMed2006

Comparison of myocardial velocities obtained with magnetic resonance phase velocity mapping and tissue Doppler imaging in normal subjects and patients with left ventricular dyssynchrony.

PURPOSE: To compare longitudinal myocardial velocity and time to peak longitudinal velocity obtained with magnetic resonance phase velocity mapping (MR-PVM) and tissue Doppler imaging (TDI), and to assess the reproducibility of each method. MATERIALS AND METHODS: Longitudinal myocardial velocity was measured by TDI and MR-PVM in 10 normal volunteers and 10 patients with dyssynchrony. The reproducibility of MR-PVM and TDI was assessed on repeated measurements in the 10 normal volunteers. RESULTS: MR and TDI measurements of longitudinal myocardial velocity correlated well (r = 0.86) in both normal subjects and patients with dyssynchrony. However, myocardial velocities measured with MR consistently exceeded velocities measured with TDI. MR and TDI agreed strongly in measuring the time to peak velocity (r = 0.97). The reproducibility of TDI and MR-PVM appeared similar in measuring peak velocities (13.1% vs. 11.0%, respectively; P = NS) and time to peak velocity (9.1% vs. 5.7%, respectively; P = NS). CONCLUSION: Excellent correlation and reproducibility were observed between MR-PVM and TDI in measuring longitudinal myocardial velocity and time to peak velocity in both normal subjects and patients with dyssynchrony.

Adult↗

PubMed2005

Predictive value of ventricular arrhythmia inducibility for subsequent ventricular tachycardia or ventricular fibrillation in Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients.

UNLABELLED: In the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II, implantable cardioverter-defibrillator (ICD)-randomized patients underwent electrophysiologic testing. Both inducible and noninducible patients received an ICD. We correlated inducibility with the occurrence of subsequent ventricular tachycardia (VT) or ventricular fibrillation (VF). Intracardiac ICD electrograms for subsequent events were analyzed to categorize the spontaneous arrhythmia as VT or VF. The two-year Kaplan-Meier event rate for VT in inducible patients was 29.0% versus 19.3% in noninducible patients. However, ICD therapy for spontaneous VF was less common at two years in inducible patients (3.2%) than in noninducible patients (8.6%). In the MADIT II study, inducibility predicted an increased likelihood of VT but decreased VF. OBJECTIVES: We correlated electrophysiologic inducibility with spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II. BACKGROUND: In the MADIT II study, 593 (82%) of 720 implantable cardioverter-defibrillator (ICD) randomized patients underwent electrophysiologic testing. Patients received an ICD whether they were inducible or not. METHODS: A "standard" inducibility definition included sustained monomorphic or polymorphic VT induced with three or fewer extrastimuli or VF induced with two or fewer extrastimuli. We compared a narrow inducibility definition (only monomorphic VT) and a broad definition (standard definition plus VF with three extrastimuli). We used ICD-stored electrograms to categorize spontaneous VT or VF. RESULTS: Inducible patients (standard definition) had a greater likelihood of experiencing ICD therapy for VT than noninducible patients (p = 0.023). Unexpectedly, ICD therapy for spontaneous VF was less common (p = 0.021) in inducible patients than in noninducible patients. The two-year Kaplan-Meier event rate for VT or VF was 29.4% for inducible patients and 25.5% for noninducible patients. Standard inducibility did not predict the combined end point of VT or VF (p = 0.280, by log-rank analysis). The narrow inducibility definition outperformed the standard definition, whereas the broad definition appeared inferior to the standard definition. CONCLUSIONS: In the MADIT II study patients, inducibility was associated with an increased likelihood of VT. Noninducible MADIT II study subjects using this electrophysiologic protocol had a considerable VT event rate and a higher VF event rate than inducible patients. Induction of polymorphic VT or VF, even with double extrastimuli, appears less relevant than induction of monomorphic VT.

Aged↗

PubMed2005

Pacing and heart failure: should all patients receive a biventricular device?

The increasing adoption of biventricular pacing as a means to achieve interventricular, intraventricular, and atrioventricular synchronization affords clinicians a powerful nonpharmacologic tool in the treatment of congestive heart failure. Current guidelines support the use of cardiac resynchronization therapy (CRT) in patients with the combination of severe systolic ventricular dysfunction, symptomatic heart failure, and evidence of conduction delay on the surface electrocardiogram. Current research aims include investigation of differing clinical parameters and imaging techniques that will reliably differentiate patients who may or may not benefit from CRT. Furthermore, refinements in the techniques of lead placement and intrachamber timing may further improve the proportion of patients who achieve a favorable response from CRT. This article briefly reviews the history of CRT and summarizes some of the current trends and data relating to CRT.

Cardiac Pacing, Artificial↗

PubMed2003

Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial.

CONTEXT: Cardiac resynchronization therapy (CRT) through biventricular pacing is an effective treatment for heart failure (HF) with a wide QRS; however, the outcomes of patients requiring CRT and implantable cardioverter defibrillator (ICD) therapy are unknown. OBJECTIVE: To examine the efficacy and safety of combined CRT and ICD therapy in patients with New York Heart Association (NYHA) class III or IV congestive HF despite appropriate medical management. DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind, parallel-controlled trial conducted from October 1, 1999, to August 31, 2001, of 369 patients with left ventricular ejection fraction of 35% or less, QRS duration of 130 ms, at high risk of life-threatening ventricular arrhythmias, and in NYHA class III (n = 328) or IV (n = 41) despite optimized medical treatment. INTERVENTIONS: Of 369 randomized patients who received devices with combined CRT and ICD capabilities, 182 were controls (ICD activated, CRT off) and 187 were in the CRT group (ICD activated, CRT on). MAIN OUTCOME MEASURES: The primary double-blind study end points were changes between baseline and 6 months in quality of life, functional class, and distance covered during a 6-minute walk. Additional outcome measures included changes in exercise capacity, plasma neurohormones, left ventricular function, and overall HF status. Survival, incidence of ventricular arrhythmias, and rates of hospitalization were also compared. RESULTS: At 6 months, patients assigned to CRT had a greater improvement in median (95% confidence interval) quality of life score (-17.5 [-21 to -14] vs -11.0 [-16 to -7], P =.02) and functional class (-1 [-1 to -1] vs 0 [-1 to 0], P =.007) than controls but were no different in the change in distance walked in 6 minutes (55 m [44-79] vs 53 m [43-75], P =.36). Peak oxygen consumption increased by 1.1 mL/kg per minute (0.7-1.6) in the CRT group vs 0.1 mL/kg per minute (-0.1 to 0.8) in controls (P =.04), although treadmill exercise duration increased by 56 seconds (30-79) in the CRT group and decreased by 11 seconds (-55 to 12) in controls (P<.001). No significant differences were observed in changes in left ventricular size or function, overall HF status, survival, and rates of hospitalization. No proarrhythmia was observed and arrhythmia termination capabilities were not impaired. CONCLUSIONS: Cardiac resynchronization improved quality of life, functional status, and exercise capacity in patients with moderate to severe HF, a wide QRS interval, and life-threatening arrhythmias. These improvements occurred in the context of underlying appropriate medical management without proarrhythmia or compromised ICD function.

Aged↗

PubMed2003

Effect of cardiac resynchronization therapy on left ventricular size and function in chronic heart failure.

BACKGROUND: Cardiac resynchronization therapy (CRT) has recently emerged as an effective treatment for patients with moderate to severe systolic heart failure and ventricular dyssynchrony. The purpose of the present study was to determine whether improvements in left ventricular (LV) size and function were associated with CRT. METHODS AND RESULTS: Doppler echocardiograms were obtained at baseline and at 3 and 6 months after therapy in 323 patients enrolled in the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial. Of these, 172 patients were randomized to CRT on and 151 patients to CRT off. Measurements were made of LV end-diastolic and end-systolic volumes, ejection fraction, LV mass, severity of mitral regurgitation (MR), peak transmitral velocities during early (E-wave) and late (A-wave) diastolic filling, and the myocardial performance index. At 6 months, CRT was associated with reduced end-diastolic and end-systolic volumes (both P<0.001), reduced LV mass (P<0.01), increased ejection fraction (P<0.001), reduced MR (P<0.001), and improved myocardial performance index (P<0.001) compared with control. beta-Blocker treatment status did not influence the effect of CRT. Improvements with CRT were greater in patients with a nonischemic versus ischemic cause of heart failure. CONCLUSIONS: CRT in patients with moderate-to-severe heart failure who were treated with optimal medical therapy is associated with reverse LV remodeling, improved systolic and diastolic function, and decreased MR. LV remodeling likely contributes to the symptomatic benefits of CRT and may herald improved longer-term survival.

Cardiac Pacing, Artificial↗

PubMed2003

Benefits of cardiac resynchronization therapy in outpatients with indicators for heart transplantation.

BACKGROUND: Despite several new advances in the treatment of end-stage congestive heart failure (CHF) the number of patients moving onto the heart transplant list continues to rise. Recently, cardiac resynchronization therapy (CRT) has become a Food and Drug Administration (FDA)-approved therapy for advanced CHF. Currently, there are no available data on CRT in cardiac transplant candidates. METHODS: To determine the effects of CRT on potential transplant candidates we retrospectively reviewed patients (n = 34) enrolled in resynchronization trials at our center who met accepted criteria for transplantation. Ventricular function, oxygen uptake and New York Heart Association (NYHA) class were compared at baseline and after 6 months of active therapy for each patient. RESULTS: CRT reduced QRS duration from 178 +/- 29 to 143 +/- 17 msec (p < 0.0001) and NYHA class from 3.1 +/- 0.3 to 1.8 +/- 0.7 (p < 0.0001). Ejection fraction (EF) increased from 18.4 +/- 5.1 to 25.1 +/- 8.4% (p < 0.0001) and maximum VO(2) increased from 11.9 +/- 1.8 to 15.3 +/- 3 ml/kg/min (p < 0.0001). Only 2 of the initial 34 patients still met the criteria for transplantation at 6 months. CONCLUSIONS: CRT improves ventricular function, oxygen uptake and NYHA class in ambulatory patients who have a QRS of >130 msec and might be considered candidates for cardiac transplantation. Transplantation can be prevented or deferred in the majority of patients. Outpatients with chronic CHF and a widened QRS should be evaluated for CRT before being listed for cardiac transplantation.

Cardiac Pacing, Artificial↗

PubMed2003

Cardiac resynchronization therapy devices: patient management and follow-up strategies.

Results of numerous clinical trials support the use of cardiac resynchronization therapy (CRT) for treatment of moderate to severe heart failure in patients with cardiac dyssynchrony. Commercial approval of various CRT devices has led to a growing number of patients receiving this form of therapy. Patients with implanted CRT devices require specific attention to detect adverse events related to the device, detect failure to respond to therapy, and optimize device function. Interaction between the primary care physician, cardiologist, heart failure specialist, and electrophysiologist/implanting physician is necessary to accomplish these goals. Recognizing the signs and symptoms of adverse events or suboptimal response allows the primary care physician to alter drug therapy or, when appropriate, refer the patient to the heart failure specialist or electrophysiologist for optimization of CRT device programming or further intervention.

Cardiac Pacing, Artificial↗

PubMed2003

Practical issues in cardiac resynchronization therapy device implantation.

Cardiac resynchronization utilizes left ventricular (LV) pacing through electrodes inserted through the coronary sinus (CS) into LV veins to stimulate the LV myocardium. Successful insertion of LV pacing leads requires an understanding of the anatomic changes associated with cardiac remodeling and a combination of standard pacing and cardiac catheterization and interventional techniques. CS catheterization and venography identify and access the target LV vein for insertion of the pacing lead. Obtaining an adequate lead position involves reaching appropriate capture thresholds, avoiding extra-cardiac stimulation, and stabilizing the lead to avoid dislodgement.

Cardiac Catheterization↗

PubMed2002

Cardiac resynchronization in chronic heart failure.

BACKGROUND: Previous studies have suggested that cardiac resynchronization achieved through atrial-synchronized biventricular pacing produces clinical benefits in patients with heart failure who have an intraventricular conduction delay. We conducted a double-blind trial to evaluate this therapeutic approach. METHODS: Four hundred fifty-three patients with moderate-to-severe symptoms of heart failure associated with an ejection fraction of 35 percent or less and a QRS interval of 130 msec or more were randomly assigned to a cardiac-resynchronization group (228 patients) or to a control group (225 patients) for six months, while conventional therapy for heart failure was maintained. The primary end points were the New York Heart Association functional class, quality of life, and the distance walked in six minutes. RESULTS: As compared with the control group, patients assigned to cardiac resynchronization experienced an improvement in the distance walked in six minutes (+39 vs. +10 m, P=0.005), functional class (P<0.001), quality of life (-18.0 vs. -9.0 points, P= 0.001), time on the treadmill during exercise testing (+81 vs. +19 sec, P=0.001), and ejection fraction (+4.6 percent vs. -0.2 percent, P<0.001). In addition, fewer patients in the group assigned to cardiac resynchronization than control patients required hospitalization (8 percent vs. 15 percent) or intravenous medications (7 percent vs. 15 percent) for the treatment of heart failure (P<0.05 for both comparisons). Implantation of the device was unsuccessful in 8 percent of patients and was complicated by refractory hypotension, bradycardia, or asystole in four patients (two of whom died) and by perforation of the coronary sinus requiring pericardiocentesis in two others. CONCLUSIONS: Cardiac resynchronization results in significant clinical improvement in patients who have moderate-to-severe heart failure and an intraventricular conduction delay.

Aged↗

PubMed2002

Cardiac resynchronization in patients with congestive heart failure and chronic atrial fibrillation: effect of upgrading to biventricular pacing after chronic right ventricular pacing.

OBJECTIVES: This study assessed the effects of biventricular pacing (BVP) on ventricular function, functional status, quality of life and hospitalization in patients with congestive heart failure (CHF), prior atrioventricular (AV) junction ablation and right ventricular (RV) pacing performed for chronic atrial fibrillation (AF). BACKGROUND: Although the benefit of BVP in CHF should theoretically extend to the patient with chronic RV pacing and AF, to our knowledge, no study has determined the effects of BVP on symptoms and ventricular function in these patients. This patient population allows for the evaluation of ventricular resynchronization independent of any BVP-induced changes on the AV interval. METHODS: Twenty consecutive patients with severe CHF (ejection fraction < or = 0.35, New York Heart Association [NYHA] functional class III or IV), prior AV junction ablation and RV pacing performed for permanent AF of at least six months' duration were studied. Electrocardiograms, echocardiograms, functional status evaluations and quality of life surveys were completed before and at three to six months after implant. RESULTS: The NYHA functional classification improved 29% (p < 0.001). The left ventricular (LV) ejection fraction increased 44% (p < 0.001), the LV diastolic diameter decreased 6.5% (p <0.003) and the end-systolic diameter decreased 8.5% (p < 0.01). The number of hospitalizations decreased by 81% (p < 0.001). The scores on the Minnesota Living with Heart Failure survey improved by 33% (p < 0.01). CONCLUSIONS: We conclude that BVP improves the LV function and the symptoms of CHF in patients with permanent AF and chronic RV pacing. These benefits are comparable to those described for patients in sinus rhythm suggesting that BVP acts through ventricular resynchronization rather than optimization of the AV delay.

Aged↗

PubMed2002

Addition of a left ventricular lead to conventional pacing systems in patients with congestive heart failure: feasibility, safety, and early results in 60 consecutive patients.

Left bundle branch block worsens congestive heart failure (CHF) in patients with LV dysfunction. Asynchronous LV activation produced by RV apical pacing leads to paradoxical septal motion and inefficient ventricular contraction. Recent studies show improvement in LV function and patient symptoms with biventricular pacing in patients with CHF. The aim of this study was to determine the feasibility, safety, acute efficacy, and early effect on symptoms of the upgrade of a chronically implanted RV pacing system to a biventricular system. Sixty patients with NYHA Class III and IV underwent the upgrade procedure using commercially available leads and adapters. The procedure succeeded in 54 (90%) of 60 patients. Acute LV stimulation thresholds obtained from leads placed along the lateral LV wall via the coronary sinus compare favorably to those reported in current biventricular pacing trials. The complication rate was low (5/60, 8.3%): lead dislodgement (n = 1), pocket hematoma (n = 1), and wound infections (n = 3). During 18 months of follow-up (16.7%) of 60 patients died. Two patients that died failed the initial upgrade attempt. At 3-month follow-up, quality of life scores improved 31 +/- 28 points (n = 29), P < 0.0001). NYHA Class improved from 3.4 +/- 0.5 to 2.4 +/- 0.7 (P = < 0.0001) and ejection fraction increased from 0.23 +/- 0.8 to 0.29 +/- 0.11 (P = 0.0003). Modification of RV pacing to a biventricular system using commercially available leads and adapters can be performed effectively and safely. The early results of this study suggest patients may benefit from this procedure with improved functional status and quality of life.

Aged↗

PubMedDate not supplied

Progress in cardiovascular disease: technical considerations in cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) has been shown to improve symptoms, ventricular function, and survival in patients with left ventricular systolic dysfunction and ventricular conduction delay. Patients with moderate to severe drug-refractory heart failure symptoms along with ventricular dyssynchrony, manifested as prolongation of the QRS duration on the surface electrocardiogram, benefit from CRT. Owing to the growing awareness and application of CRT, a large number of patients have been identified as candidates for this therapy, making it necessary for clinicians involved in the care of such patients to be adequately knowledgeable of various aspects of CRT implementation. In particular, clinicians involved in the care of these patients must be aware of the practical considerations in preparing patients for the implantation procedure, careful surveillance for early or late procedure-related complications, and knowledge of the fundamental device features so as to tailor therapeutic and programming techniques to improve long-term response to CRT. This review addresses the technical considerations of the implantation procedure and device function with emphasis on the initial and long-term programming to ensure optimal delivery of CRT.

Cardiac Pacing, Artificial↗