Echocardiographic assessment of left ventricular filling during isoflurane anaesthesia

Differences between the Filling Velocities of the Left and Right Heart Ventricle in Racing Pigeons (Columba Livia F. Domestica) and the Influence of Anesthesia with Isoflurane

The ventricular filling velocities during diastole and the influence of isoflurane anesthesia on these blood flow velocities of the racing pigeon (n = 43) are evaluated by pulsed-wave (PW) Doppler sonography. Sonographic examination demonstrates an early passive ventricular (E wave) and late active (A wave) ventricular filling. The results indicate differences between the two heart ventricles. Especially, the E wave velocity of the right heart is significantly lower than in the left heart, which is explained by the crescent-shaped cavity of the right ventricle around the left ventricle. The faster active filling velocities are significantly influenced by heart rate in conscious birds. Anesthesia with isoflurane leads to a significant decrease of the diastolic blood flow velocities, and the A wave velocities of both ventricles are especially influenced. Anesthesia with isoflurane induces a high incidence of insufficiencies of the left atrioventricular valve in the preejection period. These observations indicate that a contraction of the left ventricle myocardium is important for a complete valvular closure and for normal functioning of this heart valve. The effective closure of the right atrioventricular muscle valve in anesthetized pigeons supports the observation of the fast innervation of this muscle valve via a direct connection to the right atrium.

Effects of anesthetic induction in patients with diastolic dysfunction

PURPOSE

To evaluate the effects of anesthetic induction on bi-ventricular function in patients with known preoperative left ventricular (LV) diastolic dysfunction undergoing coronary artery bypass grafting surgery (CABG).

METHODS

Fifty patients with diastolic dysfunction undergoing CABG were studied. Preoperative transthoracic echocardiographic (TTE) examination was performed on the day before surgery and transesophageal echocardiography (TEE) assessment was undertaken after induction of anesthesia with sufentanil, midazolam, isoflurane, and pancuronium. Mean arterial pressure (MAP) and heart rate (HR) were recorded. The diameters of the left atrium (LA) and right atrium (RA) and right ventricular (RV) end-diastolic area (EDA), end-systolic area (ESA) and fractional area change (FAC) were obtained from the apical 4-chamber view. The LV EDA, LV ESA and LV FAC were measured from a transgastric midpapillary view. Pulsed wave Doppler of the transmitral flow (TMF) and transtricuspid flow (TTF), pulmonary venous flow (PVF) and hepatic venous flow (HVF) were measured. Mitral (Em, Am) and tricuspid (Et, At) annulus velocities were assessed by tissue Doppler imaging (TDI). Assessment of diastolic dysfunction was graded from normal to severe using a validated score.

RESULTS

Following induction of anesthesia, HR decreased (66 +/- 12 vs 55 +/- 9 beats.min(-1), P < 0.0001) while MAP remained unchanged (86.1 +/- 9.0 vs 85.6 +/- 26.5 mmHg, P = 0.94). The diameters of the LA, RA and RV chambers increased, and these increases were associated with opposite changes in LV dimensions. The RV FAC decreased, but the LV FAC remained unchanged. While most Doppler velocities decreased (P < 0.05), a greater reduction in the atrial components of the TMF, TTF and TDI ratios was observed. The LV diastolic function score improved after induction of anesthesia (100% of patients with a score > or = = 3 pre-induction compared to 58% of patients with a score > or = 3 post-induction; P = 0.0004).

CONCLUSION

In patients with left ventricular diastolic dysfunction, cardiac dimensions and bi-ventricular filling patterns are significantly altered after induction of general anesthesia. These changes can be explained to some extent by a reduction in venous return with general anesthesia, reduced atrial contractility, and the effect of positive pressure ventilation. Although the LV diastolic function score improved after induction of anesthesia, it is difficult to dissociate this effect from that of altered loading conditions.

Diastolic heart failure in anaesthesia and critical care

Diastolic heart failure is an underestimated pathology with a high risk of acute decompensation during the perioperative period. This article reviews the epidemiology, risk factors, pathophysiology, and treatment of diastolic heart failure. Although frequently underestimated, diastolic heart failure is a common pathology. Diastolic heart failure involves heart failure with preserved left ventricular (LV) function, and LV diastolic dysfunction may account for acute heart failure occurring in critical care situations. Hypertensive crisis, sepsis, and myocardial ischaemia are frequently associated with acute diastolic heart failure. Symptomatic treatment focuses on the reduction in pulmonary congestion and the improvement in LV filling. Specific treatment is actually lacking, but encouraging data are emerging concerning the use of renin-angiotensin-aldosterone axis blockers, nitric oxide donors, or, very recently, new agents specifically targeting actin-myosin cross-bridges.

Effect of Isoflurane on Echocardiographic Left-Ventricular Relaxation Indices in Patients With Diastolic Dysfunction Due to Concentric Hypertrophy and Ischemic Heart Disease

OBJECTIVE

The purpose of this study was to investigate whether isoflurane, a known negative lusitropic agent, exacerbates diastolic dysfunction in patients with preexisting impaired relaxation.

DESIGN

Prospective, experimental study.

SETTING

Single-institution, university hospital.

PARTICIPANTS

Twenty-five patients with diastolic dysfunction due to concentric hypertrophy and ischemic heart disease undergoing elective coronary artery bypass graft surgery.

INTERVENTIONS

After approval of the local ethics committee and informed consent, patients randomly received sufentanil/midazolam anesthesia plus either 0.5 to 1.0 minimum alveolar concentration of isoflurane (n = 15) or weight-adjusted boli of urapidil (n = 10) during preparation of the internal mammary artery. Changes in hemodynamic parameters and echocardiographic diastolic indices before and after drug administration were compared. Filling pressures during the study were kept constant within normal range.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic changes measured by invasive arterial and pulmonary arterial pressures were comparable between isoflurane and urapidil. Both interventions led to a marked reduction in afterload that was accompanied by a significant increase in thermodilution cardiac output and stroke volume. Transesophageal echocardiographic relaxation indices were also comparable between groups. Transmitral and tissue Doppler E waves increased significantly, leading to larger E/A and Em/Am ratios; whereas the deceleration time and the isovolumetric relaxation time decreased significantly.

CONCLUSION

Isoflurane did not exacerbate diastolic dysfunction in patients with concentric hypertrophy and ischemic heart disease. In contrast, isoflurane led to a "normalization" of the relaxation pattern that was attributed to a reduction in left-ventricular loading conditions.

Developmental changes in left and right ventricular diastolic filling patterns in mice

Developmental changes in left and right ventricular diastolic filling patterns were determined noninvasively in isoflurane-anesthetized outbred ICR mice. Blood velocities in the mitral and tricuspid orifices were recorded in 16 embryos at days 14.5 (E14.5) and 17.5 of gestation (E17.5) using an ultrasound biomicroscope and also serially in three groups of postnatal mice aged 1-7 days (n = 23), 1-4 wk (n = 18), and 4-12 wk (n = 27) using 20-MHz pulsed Doppler. Postnatal body weight increased rapidly to 8 wk. Heart rate increased rapidly from approximately 180 beats/min at E14.5 to approximately 380 beats/min at 1 wk after birth and then more gradually to plateau at approximately 450 beats/min after 4 wk. Ventricular filling was quantified using the ratio of peak velocity of early ventricular filling due to active relaxation (E wave) to that of the late ventricular filling caused by atrial contraction (A wave) (peak E/A ratio) and the ratio of the peak E velocity to total time-velocity integral of E and A waves (peak E/total TVI ratio). Both ventricles had similar diastolic filling patterns in embryos (peak E/A ratio of 0.28 +/- 0.02 for mitral flow and 0.27 +/- 0.02 for tricuspid flow at E14.5). After birth, mitral peak E/A increased to >1 between the third and fifth day, continued to increase to 2.25 +/- 0.25 at approximately 3 wk, and then remained stable. The tricuspid peak E/A ratio increased much less but stabilized at the same age (increased to 0.79 +/- 0.03 at 3 wk). The peak E/total TVI ratio showed similar left-right differences and changes with development. Age-related changes were largely due to increases in peak E velocity. The results suggest that diastolic function matures approximately 3 wk postnatally, presumably in association with maturation of ventricular recoil and relaxation mechanisms.

[Left ventricular diastolic function: physiology, physiopathology, evaluation, therapy, consequences of anesthesia]

With the exception of cardiac surgery, the acute disturbance of the left ventricular diastole occurs mainly in the elderly. Today it represents 30 to 40% of congestive cardiac failures, however with a lower mortality than for acute systolic disturbances. Generally indicated are relaxation anomalies, proto-mesodiastolic mechanism and problems with compliance, an indicator of the pressure/volume diastolic relationship. Invasive techniques remain the standard method. Doppler echocardiography is becoming increasingly important for the assessment of diastolic function. In most cardiopathies, relaxation anomalies occur early, whereas compliance disturbances are mainly associated with advanced cardiac diseases. During anaesthesia, adverse events (auricular fibrillation, hypovolaemia) may worsen a fragile situation. Anaesthetic agents, in particular volatile agents, act on the ventricular diastole. Long-term therapy of diastolic anomalies includes agents amending left ventricular hypertrophy. Emergency therapy has not yet been systematised.