Effect on cardiac output of conversion from atrial fibrillation to normal sinus mechanism

doi:10.1016/0002-9343(66)90020-9

The American Journal of Medicine

Volume 41, Issue 2, August 1966, Pages 249-258

https://doi.org/10.1016/0002-9343(66)90020-9 Get rights and content

Abstract

Hemodynamic studies were performed before and after restoration of a normal sinus rhythm in forty-eight patients with chronic atrial fibrillation. Conversion to a sinus mechanism was achieved in twenty-six patients with quinidine and in twenty-two patients with capacitor discharged direct current.

In the quinidine-treated group, who were restudied five to ten days after conversion, the mean cardiac index had risen 22 per cent from 2.40 to 2.93 L., the circulation time had decreased from a mean of 17 to 12 seconds, the mean stroke volume had increased 44 per cent from 55 to 79 ml. and the mean arteriovenous oxygen difference had dropped from 5.4 to 4.3 cc. per 100 ml.

In the electrically treated group, who were studied serially for 3 hours after conversion, there was a gradual 12 per cent rise in cardiac index from a preconversion mean of 2.36 to 2.65 L. 180 minutes later, accompanied by commensurate improvement in the other hemodynamic parameters.

Our data confirm the experimental studies reported in lower animals and man which indicate that a normally positioned atrial systole contributes importantly to ventricular function since restoration of a normal sinus mechanism in patients with chronic atrial fibrillation is followed by a significant increase in cardiac output. The full hemodynamic benefit, however, may not be evident for several hours or days after the return of normal electrical atrial activity.

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That is because in APC, the atrium is used to guide the venous blood to the pulmonary artery, and the atrium dilates over time, resulting in AF. Once AF has developed in the patient, even with a biventricular circulation, the total CO decreases by 12% to 22%.17 That is consistent with the findings of the current study.
Patients with Fontan circulation may have heart failure resulting in atrial fibrillation during the late phase. Inotropic effects to ameliorate hemodynamics on the Fontan circulation are not well understood, especially when in atrial fibrillation. This study was performed to determine whether dobutamine therapy in patients with Fontan circulation has limited effects on improving hemodynamics.
Lumped computational models (sinus and atrial fibrillation) were used, including biventricular, atriopulmonary connection, and extracardiac total cavopulmonary connection Fontan models. The condition of atrial fibrillation including lack of atrial beat, irregular ventricular contraction, and time-varying elastance for the ventricle was introduced. A different dose of dobutamine was given by varying the elastance of the ventricle, heart rate, and peripheral resistance.
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In the Fontan circulation, atrial fibrillation itself reduced the cardiac output by approximately 25%, and dobutamine had a limited effect on increasing the cardiac output, especially when in atrial fibrillation. Maintaining sinus rhythm in patients with Fontan circulation is very important.
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Several reports describe a modest decline in cardiac output with the onset of AF. This direct effect is fully reversible after cardioversion [190–192]. The most prominent reasons are the loss of atrial contraction, the irregular heart rate and a shortened diastole [190].
Atrial fibrillation (AF) is increasingly common in the general population. It often coincides with myocardial infarction (MI) and heart failure (HF) which are also diseases in older adults. All three conditions share common cardiovascular risk factors. While hypertension and obesity are central risk factors for all three diseases, smoking and diabetes appear to have less impact on AF. To date, age is the single most important risk factor for AF in the general population. Further, epidemiological studies suggest a strong association of AF to MI and HF. The underlying pathophysiological mechanisms are complex and not fully understood. Both MI and HF can trigger development of AF, mainly by promoting structural and electrical atrial remodeling. On the other hand, AF facilitates HF and MI development via multiple mechanisms, resulting in a vicious circle of cardiac impairment and adverse cardiovascular prognosis. Consequently, to prevent and treat the coincidence of AF and HF or MI a strict optimization of cardiovascular risk factors is required.
Impact of Atrial Fibrillation on Falls in Older Patients: Which is a Problem, Existence or Persistence?
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An irregular sequence of RR intervals produces poorer hemodynamic consequences that are independent of heart rate.20 AF decreases cardiac output because of irregular ventricular rate, and also due to a lack of atrial contraction.21,22 Low cardiac output can decrease multiorgan perfusion, which may include legs.
Several studies have suggested a possible relationship between atrial fibrillation (AF) and falls. However, whether the relationship depends on AF types is unclear. We investigated the relationship between sustaining AF and falls.
Single hospital-based cohort study with a follow-up of falls within 3 years after baseline.
A total of 14,056 patients from our cohort between February 2010 and March 2016.
Incidence of falls within 3 years by baseline cardiac rhythm was measured, and we investigated the effects of AF types on incidence of falls.
The study population was divided into younger (<75 years old; n = 11,808) and older (≥75 years old; n = 2248) groups, and then divided into 3 groups according to the baseline cardiac rhythm: sinus rhythm (SR), paroxysmal AF (PAF), and persistent AF (PeAF). There were more male patients in the PeAF group; these patients had more comorbidities both in the younger and older groups. The cumulative incidence rates of falls at 1 year in patients with SR, PAF, and PeAF were similar in the younger group (0.4%, 0.4%, and 0.6%, respectively; P = .496), whereas those were significantly different in the older group (2.3%, 2.7%, and 5.0%, respectively; P = .024). In multivariate analysis, both PAF [hazard ratio (HR) 1.179; 95% confidence interval (CI) 0.553–2.511, reference SR] and PeAF (HR 1.502; 95% CI 0.635–3.556) were not associated with falls in the younger group. In the older group, PeAF was independently associated with incidence of falls (HR 2.257; 95% CI 1.262–4.037), but PAF was not (HR 1.317; 95% CI 0.673–2.574).
PeAF, not PAF, was associated independently with falls in older patients, suggesting the possible effect of irregular beats on physical frailty in the older population.
Atrial Fibrillation Is Associated With Impaired Mobility in Community-Dwelling Older Adults
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AF is associated with decreased exercise capacity in patients with heart failure.26,27 It can lead to decreased cardiac output because of an increased ventricular rate, irregular ventricular response, and loss of the atrial kick,28–30 resulting in decreased gait speed and mobility due to decreased stamina on exertion. It is likely that the AF group has reduced physical function partly due to comorbid cardiovascular or chronic conditions that may themselves lead to AF; however, chronic conditions, cardiovascular conditions, and cardiovascular medications were adjusted for in the analysis so the reductions observed are unlikely to be attributable to these.
To examine the independent associations between atrial fibrillation (AF) and objectively measured mobility in a nationally representative cohort.
Wave 1 of The Irish Longitudinal Study on Ageing (TILDA), a population-based study assessing health, economic, and social aspects of ageing.
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Participants aged 50 years or older, with Mini-Mental State Examination score of 24 or higher, and who completed at least 1 mobility test (n = 4525).
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In this sample (mean age 62.3 years; range 51–89), overall prevalence of AF was 3.1%, increasing to 6.7% in the over 70s (11.8% men; 2.8% women). In multivariate analysis, AF was independently associated with slower TUG (β 0.37; 95% confidence interval [CI] 0.07–0.71; P = .043) and slower usual gait speed (β −3.59; 95% CI −7.05 to −0.12; P = .030). There was a significant age*AF interaction effect for usual gait speed (β −0.480, 95% CI −0.907 to −0.053, P = .028). Adults with AF walked 3.77 cm/s more slowly than adults without AF at age 70, declining by 4.8 cm/s for each additional decade.
AF is independently associated with lower usual gait speed in community-dwelling adults and this effect is magnified in those aged 70 and older. This may place them at increased risk of falls, hospitalization, cognitive decline, and mortality, as well as stroke and heart failure. Early recognition and treatment of AF is vital to improve physical function and reduce this risk.
Serum parathyroid hormone--related protein levels before and after paroxysmal atrial fibrillation
2008, American Journal of Emergency Medicine
Left atrial function and ventricular filling in hypertensive patients with paroxysmal atrial fibrillation
1994, Journal of the American College of Cardiology
Objectives. We evaluated left atrial dimensions and function, as well as left ventricular structure and filling, in hypertensive patients with paroxysmal atrial fibrillation.
Background. In hypertensive patients, left atrial dilation and enhanced volume transport may facilitate arrhythmias.
Methods. Left ventricular two-dimensional and M-mode echocardiograms and pulsed Doppler echocardiography of transmitral flow were performed in 17 consecutive primary hypertensive patients with paroxysmal atrial fibrillation (group EHf) and in 34 patients with high blood pressure without this arrhythmia (group EH). Seventeen normal subjects (group N) were also investigated. Groups were matched for age and gender.
Results. The EH and EHf groups had similar systolic arterial pressures ([mean ± SD] group EH 185 ± 27, group EHf 173 ± 25 mm Hg, p = NS) and left ventricular mass index (group EH 154 ± 55, group EHf 131 ± 57.8 g/m², p = NS), and their M-mode left ventricular systolic wall stress and fractional shortening were comparable to those of normal subjects. M-mode left atrial maximal (group N 37.8 ± 6, group EH 37.9 ± 4.6, group EHf 44.6 ± 6.7 mm, p < 0.05 for group EHf vs. groups N and EH) and minimal diameters and the diameter preceding atrial contraction (group N 31 ± 3.6, group EH 34.5 ± 5, group EHf 40.4 ± 6.9 mm, p < 0.001 for group EHf vs. group N; p < 0.05 for group EHf vs. group EH) were greater in group EHf than in group EH and group N subjects, whereas only the latter diameter was increased in group EH (p < 0.05 vs. group N), so that left atrial fractional shortening was higher than normal only in group EH (group N 10.8 ± 4.4%, group EH 14.6 ± 5.5%, group EHf 9.3 ± 5.3%; group EH vs. group N, p < 0.05; group EHf vs. group EH, p < 0.05). The pulsed Doppler ratio of early to late transmitral flow rates (E and A wave velocity/time integrals × mitral annulus area) was lower than normal in group EH (group N 2.9 ± 2.2, group EH 1.75 ± 0.8, group EHf 2.8 ± 0.8; group EH vs. group N, p < 0.05; group EHf vs. group EH, p < 0.001; group EHf vs. group N, p = NS) and was “normalised” in group EHf, early flow being increased in this group (group N 42 ± 13, group EH 39 ± 29, group EHf 60 ± 17 ml; group EHf vs. group N, p < 0.05; group EHf vs. group EH, p < 0.05).
Conclusions. These results suggest that the occurrence of paroxysmal atrial fibrillation in hypertension is associated with enlargement of the left atrium, depression of its contractile function and “normalization” of the pattern of left ventricular filling and is independent of left ventricular hypertrophy and systolic wall stress. The mechanisms linking these variables remain undefined.

View all citing articles on Scopus

¹: From the Cardiopulmonary Division of the Medical Research Laboratory, Veterans Administration Hospital, Philadelphia, Pennsylvania.

^†: Deceased.

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Clinical studyEffect on cardiac output of conversion from atrial fibrillation to normal sinus mechanism

Abstract

Am. J. Cardiol.

J. Thorac. Cardiov. Surg.

Am. Heart J.

Am. J. Med.

Am. Heart J.

Am. J. Cardiol.

Lancet

Am. J. Med.

Am. J. Cardiol.

Lancet

Am. Heart J.

Clinical considerations in quinidine therapy of chronic auricular fibrillation. A study of 200 unselected patients with follow up

Acta med. scandinav.

Quinidine therapy of chronic auricular fibrillation. The occurrence and mechanism of syncope

Arch. Int. Med.

New method for terminating cardiac arrhythmias. Use of synchronized capacitor discharge

J.A.M.A.

“Cardioversion” of atrial fibrillation. A report on the treatment of 65 episodes in 50 patients

New England J. Med.

Synchronized precordial electroshock for control of cardiac arrhythmias; initial results and success after three months

J.A.M.A.

“Cardioversion” of Arrhythmias (II)

Modern Concepts Cardiovasc. Dis.

The termination of cardiac arrhythmias by direct current shock

Postgrad. M. J.

Atrial fibrillation treated with direct current countershock

Arch. Int. Med.

Treatment of atrial fibrillation after surgical repair of the mitral valve

Ann. Int. Med.

Circulatory consequences of changes in cardiac rhythm produced in patients by transthoracic direct current shock

J. Clin. Invest.

Effect on circulation of conversion of atrial fibrillation to sinus rhythm

Circulation

Haemodynamic studies during auricular fibrillation and after restoration of sinus rhythm

Brit. Heart J.

The hemodynamic effect of restoring normal sinus rhythm in patients with auricular fibrillation

Scandinav. J. Clin. & Lab. Invest.

Clinical study
Effect on cardiac output of conversion from atrial fibrillation to normal sinus mechanism