Right ventricular pulsus alternans during acute increase in afterload during balloon pulmonic valvuloplasty

Comparison of patients with pulmonary arterial hypertension with versus without right-sided mechanical alternans

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.

Mechanical alternans in patients with chronic heart failure

BACKGROUND

Clinical implications of mechanical alternans in patients with chronic heart failure have remained uncertain. In this study, prevalence, characteristics, and prognostic implications of mechanical alternans were investigated.

METHODS AND RESULTS

Consecutive 51 patients with dilated cardiomyopathy underwent diagnostic cardiac catheterization using a micromanometer-tipped catheter. Under basal conditions, 7 of 35 patients with sinus rhythm showed mechanical alternans. Physiologic tachycardia (110 bpm) induced mechanical alternans in another 15 patients with sinus rhythm and in another 10 of 16 patients with atrial fibrillation. Low doses of dobutamine also induced mechanical alternans in another 8 patients, but a high dose of dobutamine eliminated mechanical alternans. Consequently, 40 patients (78%) showed mechanical alternans. Mechanical alternans was always accompanied by alternating changes of positive dP/dt, a parameter of contractility during isovolumetric contraction time, but negative dP/dt was occasionally constant. Concordant mechanical alternans between both ventricles was more prevalent than discordant alternans. The left ventricular end-diastolic volume indices and end-systolic volume indices of patients with mechanical alternans were larger than those of patients without. The left ventricular ejection fraction of patients with alternans was significantly lower than that of patients without.

CONCLUSIONS

Mechanical alternans was highly prevalent in patients with chronic heart failure. The origin of mechanical alternans seems to exist before or at the isovolumetric contraction time.

Right-sided pulsus alternans in diastolic left ventricular dysfunction

Pulsus alternans is usually found in patients with reduced systolic ventricular function. We describe a patient with shortness of breath, hypertension, and left ventricular hypertrophy, but with normal left and right systolic function. Pulsus alternans was demonstrated in the pulmonary wedge position, pulmonary artery, and right ventricle, but not in the aorta or left ventricle. Cathet. Cardiovasc. Intervent. 47:336-339, 1999.

Cardiac alternans: diverse mechanisms and clinical manifestations

OBJECTIVES

The purpose of this review is to assemble the widely dispersed information about cardiac alternans and to categorize the types and mechanisms of alternans, their clinical manifestations and possible therapeutic implications.

BACKGROUND

The phenomena of mechanical and electrical alternans have been of continuing interest to both physiologists and clinicians. Recent studies have enhanced this interest because of the reported association of alternans with experimental myocardial ischemia and cardiac arrhythmias.

METHODS

The review formulates concepts based on extensive review of published studies and personal observations.

RESULTS

Cardiac alternans has been subdivided into the following four categories: 1) mechanical, 2) electrical, 3) in association with myocardial ischemia, and 4) in association with cardiac motion. Mechanical alternans can be explained by hemodynamic or inotropic alterations, or both. Mechanical alternans in the ventricular muscle is accompanied by alternans of action potential shape. In the Purkinje fibers, action potential duration alternates without change in shape and is determined by the duration of the preceding diastolic interval. However, in ventricular muscle fiber, alternans can occur in the presence of constant diastolic intervals. T wave alternans reflects changes in action potential duration and is frequently associated with a long QT interval. Electrocardiographic manifestations of conduction alternans occur at many different sites within the conducting system and myocardium. During myocardial ischemia, additional mechanisms of repolarization alternans have been proposed. Alternans occurring in the presence of a large pericardial effusion is attributed to swinging motion of the heart maintaining two-beat periodicity.

CONCLUSIONS

Since its origin as "pulsus alternans" described by Traube in 1872, the definition of alternans has evolved into a term encompassing multiple physiologic and pathologic phenomena that, although united by the term cardiac alternans, diverge widely with respect to etiology, mechanism and clinical significance.

Balloon pulmonary valvuloplasty: results of the Valvuloplasty and Angioplasty of Congenital Anomalies Registry

Eight hundred twenty-two balloon pulmonary valvuloplasties were reported to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry. Before and after systolic outflow gradients were recorded in 784 valvuloplasties, and the gradient decreased from 71 +/- 33 to 28 +/- 21 mm Hg. The sites of residual obstructions could be ascertained in 196 patients. In these, the total systolic outflow gradients decreased from 85 +/- 41 mm Hg to 33 +/- 27 mm Hg. Of this total residual gradient, 16 +/- 15 mm Hg was transvalvar and 18 +/- 24 mm Hg was infundibular. The degree to which infundibular obstruction subsequently resolved was not determined in this study. The procedure was less effective in reducing outflow gradients in patients with dysplastic valves with or without Noonan's syndrome. There were 5 major complications (0.6%), including 2 deaths (0.2%), a cardiac perforation with tamponade (0.1%) and 2 tricuspid insufficiencies (0.2%). There were 11 minor complications (1.3%) and 21 incidents (2.6%). The incidence of major complications, minor complications and incidents was inversely related to age; it was substantially higher in infants and, in particular, neonates. Balloon pulmonary valvuloplasty is a safe and effective method of lowering pulmonary outflow gradients in infants, children and adults. Small transvalvar and varied infundibular gradients commonly are present at the end of the procedure. Assessing the full effect of the procedure requires intermediate-term follow-up and assessing the duration of relief requires long-term follow-up.

Changes in intracellular calcium during mechanical alternans in isolated ferret ventricular muscle

Alternans in heart is important as pulsus alternans in cardiac failure and electrophysiological alternans in myocardial ischemia. The explanation of this phenomenon is still unclear. We attempted to investigate the cellular mechanisms of alternans by measuring intracellular free calcium concentration [( Ca2+]i) with the photoprotein aequorin in isolated ferret papillary muscles. Tension and length were also recorded simultaneously. Transient mechanical alternans lasting five to 20 contractions could be reliably induced in this preparation by following a 30-second rest period with stimulation at a fast rate (2-4 Hz). Production of sustained mechanical alternans, which lasted longer than 20 contractions and could persist for several hundred contractions, required additional interventions, consisting of a lower temperature (25 degrees C), a lower external calcium concentration (1 mM), and a lower pH (6.91) than control conditions (0.33-0.5 Hz, 30 degrees C, 2 mM Ca2+, pH 7.36). Transient mechanical alternans was associated with transient in-phase alternation of aequorin light and, hence, [Ca2+]i. Sustained mechanical alternans was associated with sustained in-phase alternation of aequorin light as well as incomplete relaxation of tension. However, when muscles were switched from isometric to unloaded isotonic contraction, relaxation between stimuli was complete but contraction and the aequorin light signal continued to alternate. The addition of 10 mM caffeine or 10 microns ryanodine abolished transient and sustained mechanical alternans and also abolished the associated alternation of aequorin light. Commensurate with the action of ryanodine, which allows the sarcoplasmic reticulum to reaccumulate calcium to a limited extent after a period of rapid stimulation, sustained mechanical alternans sometimes reappeared in an attenuated form 30 to 50 contractions after the addition of ryanodine. These results demonstrate that incomplete muscle relaxation between beats need not be present for alternans to occur, and support the hypothesis that alternans is caused by intracellular calcium cycling involving the sarcoplasmic reticulum.