The clinical implications of mechanical alternans in patients with pulmonary arterial hypertension (PAH) remain unknown. In this study, the prevalence, characteristics, and prognostic implications of mechanical alternans in patients with PAH were investigated. Thirty-two consecutive patients with PAH confirmed by cardiac catheterization from 2000 to 2010 were included in this cohort study. During cardiac catheterization, 8 patients (25%) showed mechanical alternans at rest. All alternans were detected in the right ventricle and pulmonary trunk. Serum level of brain natriuretic peptide (584 ± 177 vs 238 ± 252 pg/ml, p = 0.001), World Health Organization functional class (3.5 ± 0.5 vs 2.9 ± 0.4, p = 0.02), mean pulmonary arterial pressure (59 ± 10 vs 47 ± 18 mm Hg, p = 0.03), mean right atrial pressure (10 ± 4 vs 5 ± 4 mm Hg, p = 0.01), right ventricular end-diastolic pressure (15 ± 5 vs 9 ± 5 mm Hg, p = 0.01), and heart rate at catheterization (96 ± 17 vs 70 ± 11 beats/min, p = 0.003) were significantly higher in patients with alternans than in those without. Twelve-month mortality of patients with alternans was higher than in patients without alternans (p = 0.03): the 12-month survival rate after cardiac catheterization was 37% for the alternans group and 75% for the group without alternans. In conclusion, isolated right-sided mechanical alternans is not an uncommon event in patients with PAH. The existence of alternans is associated with the severity of PAH and right ventricular dysfunction and implies a poor prognosis in the short term.
Pulsus alternans is a mysterious phenomenon of alternating strong and weak beats with a constant beat-to-beat interval. Although its mechanism is obscure, it is considered a hallmark of advanced left ventricular dysfunction and is associated with a poor prognosis. This pulse pattern may occur simultaneously or independently in the systemic as well as the pulmonary circulation. Ferrer et al reported 6 cases of independent alternation of the pulmonary artery, and 5 of the 6 patients had moderate to severe pulmonary arterial hypertension (PAH). However, there has been no systematic study, so the clinical implications and mechanisms of isolated right-sided mechanical alternans remain unknown. Thus, in the present study, we investigated the prevalence and characteristics of mechanical alternans in PAH. Prognostic implications and possible mechanisms of alternans in patients with PAH are also discussed.
Methods
Subjects for the present study were 32 consecutive patients who had been diagnosed as having PAH after cardiac catheterization from 2000 to 2010 at our hospital. PAH was defined as a mean pulmonary arterial pressure ≥25 mm Hg at rest on right-sided cardiac catheterization, with a pulmonary capillary wedge pressure <15 mm Hg. Patients with PAH associated with congenital heart disease, lung disease, valvular disease, and chronic thromboembolism were excluded. All patients were followed for >1 year or until death. The patients received conventional therapy from the hospital’s cardiologists. The decisions to use drugs in individual patients were left to the attending physicians. Our study was approved by the committee of Niigata University Hospital, and all patients provided informed consent.
All patients underwent right-sided cardiac catheterization using a Swan-Ganz catheter for diagnosis of PAH. Cardiac output was obtained by the thermodilution method using the mean of 3 measurements. Pulmonary vascular resistance was calculated as (mean pulmonary arterial pressure − pulmonary capillary wedge pressure)/cardiac output × 80. Arterial blood pressure was measured invasively through an arterial line by placing a cannula needle in the radial or femoral artery.
Mechanical alternans was detected by direct pressure measurement. Mechanical alternans was defined as a constant alternating pressure >4 mm Hg and continuing for >20 beats.
Data were statistically analyzed using SPSS for Windows version 13 (SPSS, Inc., Chicago, Illinois). To calculate statistical differences between 2 groups, unpaired Student’s t tests were used for continuous variables, and Fisher’s exact tests were used for categorical variables. Survival after cardiac catheterization was assessed using the Kaplan-Meier method with log-rank tests. Differences were considered significant at p <0.05. Data are expressed as mean ± SD.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
