Conduit Flow Compensates for Impaired Left Atrial Passive and Booster Functions in Advanced Diastolic Dysfunction.

BACKGROUND: Quantification of left atrial (LA) conduit function and its contribution to left ventricular (LV) filling is challenging because it requires simultaneous measurements of both LA and LV volumes. The functional relationship between LA conduit function and the severity of diastolic dysfunction remains controversial. We studied the role of LA conduit function in maintaining LV filling in advanced diastolic dysfunction. METHODS: We performed volumetric and flow analyses of LA function across the spectrum of LV diastolic dysfunction, derived from a set of consecutive patients undergoing multiphasic cardiac computed tomography scanning (n=489). From LA and LV time-volume curves, we calculated 3 volumetric components: (1) early passive emptying volume; (2) late active (booster) volume; and (3) conduit volume. Results were prospectively validated on a group of patients with severe aortic stenosis (n=110). RESULTS: The early passive filling progressively decreased with worsening diastolic function (P<0.001). The atrial booster contribution to stroke volume modestly increases with impaired relaxation (P=0.021) and declines with more advanced diastolic function (P<0.001), thus failing to compensate for the reduction in early filling. The conduit volume increased progressively (P<0.001), accounting for 75% of stroke volume (interquartile range, 63-81%) with a restrictive filling pattern, compensating for the reduction in both early and booster functions. Similar results were obtained in patients with severe aortic stenosis. The pulmonary artery systolic pressure increased in a near-linear fashion when the conduit contribution to stroke volume increased above 60%. Maximal conduit flow rate strongly correlated with mitral E-wave velocity (r=0.71; P<0.0001), indicating that the increase in mitral E wave in diastolic dysfunction represents the increased conduit flow. CONCLUSIONS: An increase in conduit volume contribution to stroke volume represents a compensatory mechanism to maintain LV filling in advanced diastolic dysfunction. The increase in conduit volume despite increasing LV diastolic pressures is accomplished by an increase in pulmonary venous pressure.

Risk of malignant ventricular arrhythmias in patients with mildly to moderately reduced ejection fraction after permanent pacemaker implantation.

BACKGROUND: Many patients with mildly to moderately reduced left ventricular ejection fraction (LVEF) who require permanent pacemaker (PPM) implantation do not have a concurrent indication for implantable cardioverter-defibrillator (ICD) therapy. However, the risk of ventricular tachycardia/ventricular fibrillation (VT/VF) in this population is unknown. OBJECTIVE: The aim of this study was to describe the risk of VT/VF after PPM implantation in patients with mildly to moderately reduced LVEF. METHODS: Retrospective analysis was performed of 243 patients with LVEF between 35% and 49% who underwent PPM placement and did not meet indications for an ICD. The primary end point was occurrence of sustained VT/VF. Competing risks regression was performed to calculate subhazard ratios for the primary end point. RESULTS: Median follow-up was 27 months; 73% of patients were male, average age was 79 ± 10 years, average LVEF was 42% ± 4%, and 70% were New York Heart Association class II or above. Most PPMs were implanted for sick sinus syndrome (34%) or atrioventricular block (50%). Of 243 total patients, 11 (4.5%) met the primary end point of VT/VF. Multivessel coronary artery disease (CAD) was associated with significantly higher rates of VT/VF, with a subhazard ratio of 5.4 (95% CI, 1.5-20.1; P = .01). Of patients with multivessel CAD, 8 of 82 (9.8%) patients met the primary end point for an annualized risk of 4.3% per year. CONCLUSION: Patients with mildly to moderately reduced LVEF and multivessel CAD undergoing PPM implantation are at increased risk for the development of malignant ventricular arrhythmias. Patients in this population may benefit from additional risk stratification for VT/VF and consideration for upfront ICD implantation.

Acute and severe ribavirin-associated hyperuricemia and acute kidney injury: An underrecognized adverse effect.

PURPOSE: To report a case of ribavirin-associated severe hyperuricemia in an immunocompromised patient treated for respiratory syncytial virus (RSV) infection. SUMMARY: A 21-year-old male with a past medical history of B-cell acute lymphoblastic leukemia was in full remission after allogenic bone marrow transplantation complicated with chronic graft-versus-host disease. He was hospitalized due to fever, malaise, and respiratory symptoms. A diagnosis of RSV upper respiratory tract infection complicated by secondary pneumonia was made, and oral ribavirin (600 mg in 3 divided doses daily) and intravenous levofloxacin (750 mg once daily) were initiated. On day 2 of the hospital admission, the patient's uric acid levels had increased from a baseline of 4 to 6 mg/dL to 19.3 and 22.2 mg/dL after the fourth and fifth doses of ribavirin, respectively, and his serum creatinine steadily had increased from a baseline of 0.7 to 0.8 mg/dL to 1.6 mg/dL. Ribavirin was discontinued after the sixth dose, and a single dose of intravenous rasburicase (7.5 mg) was administered. On day 3, the patient's serum uric and creatinine concentrations had decreased to 4.7 mg/dL and 1.1 mg/dL, respectively. He continued to recover on antibiotics and was discharged with normal uric acid and serum creatinine levels. CONCLUSION: We report a case of severe hyperuricemia and acute kidney injury that developed early after initiation of ribavirin for RSV infection and suspected bacterial pneumonia in an immunocompromised patient without hepatitis C, requiring ribavirin discontinuation and rasburicase administration. To our knowledge, this is the first reported case of severe hyperuricemia in a patient treated with ribavirin for RSV infection rather than chronic hepatitis C. Clinicians should be aware of the possibility of acute and severe hyperuricemia following ribavirin administration.

Longitudinal changes in cardiac function in the very elderly: the Jerusalem longitudinal cohort study.

BACKGROUND: People over the age of 85 are a rapidly growing age group with a high incidence of congestive heart failure (CHF), in particular heart failure with preserved ejection fraction (HFpEF). The diagnosis of CHF is challenging and longitudinal data assessing cardiac structure and function are necessary to distinguish physiologic from pathologic cardiac aging. The objective of the study was to determine longitudinal changes in cardiac struture and function from ages 85 to 94 years using home echocardiography. METHODS: Subjects were recruited from the Jerusalem Longitudinal Cohort Study. Sixty three members of the initial cohort (32F, 31M) who underwent home echocardiography at age 85 were the subjects of the current study and underwent repeat home 2-D and Doppler echocardiographic assessment at age 94. RESULTS: There were no significant longitudinal changes in left ventricular mass index (LVMI), however LV end-diastolic volume significantly decreased from 113.4 ± 30 to 103.6 ± 35.5 mL (P < 0.02). Ejection fraction (EF) remained stable, however longitudinal systolic function significantly decreased with age from 7.9 ± 1.8 to 6.6 ± 1.4 cm/s2 (P < 0.0001). Diastolic function as assessed by increased E: e' (11.2 ± 3.4 to 16 ± 7.5, P < 0.0001) and increased left atrial volume index (34.1 ± 11.3 to 42.4 ± 13.7 mL/m2, P < 0.0001) was reduced with aging. CONCLUSIONS: This study demonstrated preserved EF with decreased longitudinal systolic function and diastolic function without significant change in LV mass. Changes in LV function in the very elderly may be independent of changes in LV geometry.