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Biomedical subjects

Raveen Bazaz

Publications and source records attributed to Raveen Bazaz.

15 recordsLinked to original sources
PubMed2006

Right ventricular systolic function is not the sole determinant of tricuspid annular motion.

Maximal tricuspid annular plane systolic excursion (TAPSE) correlates well with right ventricular (RV) function; however, little is known regarding the impact of left ventricular (LV) systolic function on TAPSE. Consequently, TAPSE was examined in 206 patients (105 men; mean age 56 +/- 17 years), and the data were analyzed with respect to RV (RV fractional area change 45 +/- 19%) and LV (56 +/- 17%) systolic function. The mean TAPSE for the population studied was 1.97 +/- 0.72 cm. Although a strong linear correlation was noted between RV fractional area change and TAPSE (r = 0.73, p <0.0001), relative differences with regard to TAPSE were also found. First, the greatest TAPSE was noted only when RV and LV systolic function were normal (2.46 +/- 0.50 cm). Second, patients with reduced RV systolic function had the smallest TAPSE (1.28 +/- 0.48 cm, p <0.0001). Third, patients with normal RV function but reduced LV systolic function had TAPSE (1.91 +/- 0.54 cm, p <0.0001) that was intermediate between that of patients with normal RV and LV systolic function and those with abnormal RV systolic function. Fourth, patients with reduced biventricular function had the smallest TAPSE (1.16 +/- 0.41 cm, p <0.0001). In conclusion, TAPSE is not only determined by RV systolic function but also appears to depend on LV systolic function. TAPSE <2.0 cm is associated with some degree of either RV or LV dysfunction, whereas a value >2.0 cm suggests normal biventricular systolic function.

Adult↗
PubMed2006

Relation of advanced heart failure symptoms to risk of inappropriate defibrillator shocks.

Inappropriate implantable cardioverter-defibrillator (ICD) shocks continue to be a major source of distress to patients and a drain on the health care system. Expanding indications for ICD implantation include a large portion of patients with heart failure. This study investigated the relation between inappropriate ICD shocks and the severity of heart failure symptoms. Predictors of the time to first inappropriate ICD therapy were investigated in 230 consecutive patients implanted in 2001 and 2002. Thirty-two patients received 42 inappropriate shocks during a median follow-up of 501 days. Inappropriate shocks were due to atrial fibrillation (AF) or tachycardia (n = 31), other supraventricular tachycardias (n= 6), sinus tachycardia (n = 3), and noise or double counting (n = 2). The time to first inappropriate ICD shock was earliest in patients with advanced classes of heart failure (1- and 2-year shock-free survival of 79% and 70% for patients in New York Heart Association [NYHA] class III or IV vs 92% and 88% for patients in NYHA class I or II, respectively, p = 0.02). After correcting for age, gender, the presence of coronary artery disease, the presence of AF, the use of beta blockers, and indication for ICD implantation in a Cox regression model, advanced heart failure (NYHA class III or IV) remained an independent predictor of first inappropriate ICD shocks (hazard ratio 2.7, p = 0.01). Other predictors of the time to first inappropriate ICD shock included the presence of AF as the baseline rhythm at the time of the ICD implantation and the absence of coronary disease. In conclusion, inappropriate ICD shocks are predominantly due to AF. Advanced heart failure is an independent predictor of the time to first inappropriate ICD shocks. The effect of ICD programming and antiarrhythmic drug therapy on the incidence of inappropriate shocks deserves further investigation.

Atrial Fibrillation↗
PubMed2006

Renal insufficiency predicts the time to first appropriate defibrillator shock.

BACKGROUND: Indications for implantable cardioverter defibrillator (ICD) implantation are expanding, but many primary and secondary ICD trials have excluded patients with advanced renal insufficiency. We investigated the effect of renal function on the incidence and time to first appropriate ICD shock. METHOD: We analyzed data from all new ICD implantations at a tertiary care center from July 2001 to December 2002. RESULTS: During a mean follow-up time of 445 +/- 285 days, 29 (13%) of 230 patients (age 63 +/- 14 years, 79% men, 77% white, 75% coronary artery disease, left ventricular ejection fraction 0.28 +/- 0.14) received 41 appropriate shocks. Patients were divided into tertiles according to their serum creatinine level. The 1-year incidence of appropriate ICD shock was 3.8%, 10.8%, and 22.7% in the first, second, and third tertiles, respectively (P = .003). Using the same cut off values of serum creatinine, the 1-year incidence of appropriate ICD therapy (shock and antitachycardia pacing) was 8.8%, 20.8%, and 26.3% (P = .02). After correcting for age, sex, race, left ventricular ejection fraction, indication for ICD implantation, and use of beta-blockers in a Cox regression model, serum creatinine was still an independent predictor of the time to first appropriate ICD shock (hazard ratio 6.0 for the third compared with the first tertile, P = .001). CONCLUSION: Renal insufficiency is a strong predictor of appropriate ICD shocks. Defibrillator therapy should therefore not be withheld based on the presence of this comorbidity. The mechanisms underlying the relationship between renal function and ventricular arrhythmias deserve further investigation.

Aged↗
PubMed2006

An abnormal right ventricular apical angle is indicative of global right ventricular impairment.

The presence of right ventricular (RV) dysfunction is an adverse prognostic indicator but current echocardiographic methods have some limitations. RV apical angles in systole and diastole were correlated with known parameters of RV function in patients without pulmonary hypertension (Group 1) and in patients with pulmonary hypertension (Group 2). RV apical angles were significantly smaller in both systole (22 +/- 7 degrees) and diastole (33 +/- 6 degrees) in Group 1 patients when compared to Group 2 (54 +/- 18 degrees, p < 0.0001 and 59 +/- 17 degrees, p < 0.0001, respectively). RV apical angles, both in systole and diastole, were strongly correlated with RV end-systolic area (R = 0.89, p < 0.0001) and end-diastolic area (R = 0.81, p < 0.0001), respectively. Similarly, the apical systolic and diastolic angle correlated well with decreased tricuspid annular plane systolic excursion (TAPSE, R = -0.76 and R = -0.73, p < 0.001) as well as with decreased RV fractional area change (R = -0.81 and R = -0.77, p < 0.001). Therefore, we conclude that this new measurement of RV apical angle is simple and useful to quantify RV apical structural and functional abnormalities that are well correlated with global RV impairment in patients with chronic pulmonary hypertension.

Adult↗
PubMed2005

Relation of right ventricular free wall mechanical delay to right ventricular dysfunction as determined by tissue Doppler imaging.

Several well-established echocardiographic parameters used in the assessment of right ventricular (RV) performance, as well as tissue Doppler imaging (TDI) to investigate RV free wall mechanical events, were prospectively obtained from a heterogenous group of 20 patients with varying degrees of pulmonary hypertension (mean age 51 +/- 13 years; World Health Organization class average 2.8, mean pulmonary systolic pressure 78 +/- 24 mm Hg) and compared with similar data retrospectively obtained from 20 healthy volunteers (mean age 45 +/- 15 years). Patients with varying degrees of pulmonary hypertension had worse RV performance parameters than healthy volunteers (RV fractional area change 37 +/- 13% vs 52 +/- 5%, p < 0.0001; RV myocardial performance index 0.76 +/- 0.31 vs 0.29 +/- 0.11, p < 0.0001; and eccentricity index 1.41 +/- 0.57 vs 0.98 +/- 0.06, p < 0.005). Similarly, in these patients with abnormal RV performance, TDI showed statistically significant smaller peak longitudinal RV free wall strain (-21.5 +/- 9.0% vs -28.0 +/- 4.1%, p < 0.01) and significantly delayed time to peak strain (459 +/- 76 vs 388 +/- 29 ms, p < 0.0005) values than in healthy volunteers; a very strong correlation between RV mechanical delay and RV fractional area change (r = -0.89) was noted.

Adult↗
PubMed2005

Benefit of cardiac resynchronization therapy to a patient with a narrow QRS complex and ventricular dyssynchrony identified by tissue synchronization imaging.

This report described an 81-year-old woman with severe symptomatic heart failure, reduced ejection fraction, mitral regurgitation, and an electrocardiographic QRS width of 118 ms who had ventricular dyssynchrony identified by echocardiographic tissue synchronization imaging. Because of her severe heart failure symptoms on maximal medical therapy, referral to implant a defibrillator, and mechanical dyssynchrony, she underwent cardiac resynchronization-defibrillator therapy with lateral left ventricular lead placement. This resulted in an immediate 30% increase in stroke volume and 35% decrease in mitral regurgitation. Echocardiographic tissue synchronization imaging may play a role in identifying mechanical dyssynchrony in patients with narrow QRS duration who may potentially benefit from cardiac resynchronization therapy.

Aged, 80 and over↗
PubMed2004

A mechanism for immediate reduction in mitral regurgitation after cardiac resynchronization therapy: insights from mechanical activation strain mapping.

OBJECTIVES: We tested the hypothesis that an immediate reduction in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT) results from improved coordinated timing of the papillary muscle insertion sites, using the novel approach of mechanical activation strain mapping. BACKGROUND: Heart failure patients with left bundle branch block often benefit acutely from CRT; however, the role and mechanism of reduction of MR are unclear. METHODS: Twenty-six consecutive patients undergoing CRT with at least mild MR were studied (ejection fraction 24 +/- 6%; QRS duration 168 +/- 30 ms). Echocardiographic Doppler and strain imaging was performed immediately before and the day after CRT, as well as in 10 normal control subjects. Mechanical activation sequence maps were constructed using longitudinal strain from 12 basal and mid-LV sites, with color coding of time-to-peak strain. RESULTS: Mitral regurgitation by the volumetric method consistently decreased after CRT: regurgitant volume from 40 +/- 20 ml to 24 +/- 17 ml and regurgitant fraction from 40 +/- 12% to 25 +/- 14% (both: p < 0.001 vs. baseline). Normal controls had uniform segmental time-to-peak strain, with a difference of only 12 +/- 8 ms between all segments. In contrast, CRT patients at baseline had a 106 +/- 74 ms time delay between papillary muscle insertion sites (p < 0.001 vs. normal). This interpapillary muscle time delay shortened after CRT to 39 +/- 43 ms (p < 0.001 vs. baseline) and was significantly correlated with reductions in mitral regurgitant fraction (r = 0.77, p < 0.001). CONCLUSIONS: Cardiac resynchronization therapy significantly and immediately reduced MR. Improved coordinated timing of mechanical activation of papillary muscle insertion sites appears to be a mechanistic contributor to immediate MR reduction by CRT.

Aged↗
PubMed2004

Usefulness of echocardiographic tissue synchronization imaging to predict acute response to cardiac resynchronization therapy.

Echocardiographic tissue synchronization imaging (TSI) consists of color-coding time-to-peak tissue Doppler velocities. This study of 29 patients who underwent cardiac resynchronization therapy (CRT) demonstrated that differences in baseline time-to-speak velocities of opposing ventricular walls by TSI were greater in 15 patients, with an acute hemodynamic improvement. A >/=65 ms delay from the anterior septum to the posterior wall using the apical long-axis view had 87% sensitivity and 100% specificity for predicting an acute response. Although a subgroup without acute improvement had later decreases in end-systolic volume, suggesting that acute response underestimates long-term effects, TSI has potential to assist in guiding CRT.

Aged↗
PubMed2004

Common left pulmonary vein: a consistent source of arrhythmogenic atrial ectopy.

INTRODUCTION: The discovery of a consistent relationship between atrial anatomy and electrophysiology would have practical value and may provide insight into arrhythmia mechanism. We previously observed that anatomically common left pulmonary veins were a disproportionate source of atrial ectopy that was associated with the initiation of atrial fibrillation ("arrhythmogenic"). This report details our efforts to characterize and quantify this observation. METHODS AND RESULTS: One hundred subjects with paroxysmal atrial fibrillation underwent computed tomographic scanning to characterize left atrial anatomy and invasive electrophysiology study to characterize events associated with the initiation of atrial fibrillation. Some of these subjects also underwent radiofrequency catheter ablation. The left pulmonary vein was common in 14 subjects and was a consistent source of arrhythmogenic ectopy. This relationship was significantly stronger than for any other individual vein or ipsilateral vein combination. Myocardium located within the common vein trunk was the site of origin of the ectopy in most subjects. This myocardium did not have unique electrophysiologic properties. Catheter ablation to isolate myocardium proximal to junction between the common vein and the left atrial body cured all patients in whom the vein was the sole source of arrhythmogenic ectopy. CONCLUSION: In this cohort, a common left pulmonary vein was a consistent source of arrhythmogenic atrial ectopy.

Atrial Fibrillation↗
PubMed2004

Impact of catheter ablation on pulmonary vein morphology and mechanical function.

INTRODUCTION: Previous reports have documented that radiofrequency catheter ablation of pulmonary veins induces a significant increase in the peak velocity of transvenous blood flow. Although the magnitude of the increase infers a state of pulmonary vein stenosis, there have been no reports of direct visualization of the ablation zone. METHODS AND RESULTS: In each of 23 subjects, the myocardium investing one or more pulmonary veins (total of 42 veins) was electrically isolated by applying a confluent circumferential ablation lesion to the atrial side of the venoatrial junction. Doppler measurements of transvenous flow velocity were made before and after ablation using phased-array intracardiac echocardiography. Direct visualization of the ablation zone was performed using rotating intracardiac echocardiography, permitting assessment of shape, cross-sectional area, phasic variation in cross-sectional area, and wall thickness. In a subset of 5 subjects, a more detailed assessment of the ablation and contiguous regions was performed using three-dimensional echocardiography (rotating transducer). Prior to ablation, venoatrial junctions demonstrated noncircular shape and marked phasic variation in cross-sectional area. There was a trivial transvenous pressure gradient. After ablation, there was a significant increase in both anterograde and retrograde flow velocities and pressure gradient, the magnitudes of which were inversely proportional to the preablation and postablation areas. Direct visualization of the ablation zone revealed circumferential wall swelling, reduced cross-sectional area, and diminishment in phasic variation in cross-sectional area. Similar observations were made at contiguous nonablated sites, diminishing in magnitude as a function of distance. CONCLUSION: Pulmonary vein ablation induces significant acute changes in morphology and mechanical function that extend beyond the ablation zone.

Adult↗
PubMed2003

Catheter ablation to suppress atrial fibrillation: evolution of technique at a single center.

BACKGROUND: Catheter ablation of atrial fibrillation is a rapidly evolving art. There is currently no consensus as to optimal methodology. We report a sequential experience, during which three distinct ablation techniques were utilized. METHODS: A cohort of 112 patients in whom atrial fibrillation onset was precipitated by ectopy arising solely from myocardium investing the pulmonary veins underwent catheter ablation using one of three techniques: focal (Group A); individual vein encircling (Group B); vestibule encircling (Group C). In each group, non-fluoroscopic guidance of the mapping and ablation process was provided by the tandem use of CARTO and intracardiac echocardiography. RESULTS: In all groups, endocardial topography was complex, and ablation electrode-endocardial contact was often unstable. Maximal electrode temperatures were low, despite frequent echocardiographic evidence of myocardial boiling. A significant progression in the number of radiofrequency energy applications between groups A and C was observed. Although acute suppression of atrial fibrillation inducibility was observed uniformly, chronic suppression rates were significantly different: Group A = 47%; Group B; 69%; Group C = 87%. CONCLUSIONS: In this non-concurrent cohort, the rate of chronic suppression of atrial fibrillation correlated with the amount of myocardium ablated or electrically isolated. Prospective data will be required to further evaluate whether "more is better."

Adult↗
PubMed2003

Site-selective atrial septal puncture.

Atrial transseptal puncture is a technique that provides pervenous access to the left heart. The aim of this technique is to provide catheter access to the left atrium and ventricle for mapping, as well as stable electrode-endocardial contact for ablation energy application. In the present report, "site-selective" atrial septal puncture is described and illustrated using case reports.

Adult↗