The effect of pericardial restraint, atrial pacing, and increased heart rate on left ventricular systolic and diastolic function in patients undergoing cardiac surgery

Left ventricular contractile function is preserved during prolonged exercise in middle-aged men

We examined left ventricular (LV) performance before, during, and following prolonged exercise (EX) in 12 healthy middle-aged men [means ± SE: age = 43.5 ± 1.9 yr; maximal O2 uptake (V̇o2max) = 51.7 ± 1.5 ml·kg−1·min−1]. Subjects cycled for 120 min at 65% V̇o2max (75% of maximal heart rate). Two-dimensional echocardiography (ECHO) to determine tissue-Doppler longitudinal myocardial strain and strain rate, LV ejection fraction (EF), end-diastolic (EDV), end-systolic (ESV), and stroke volume (SV) at baseline and after 5, 30, and 120 min of EX and following 30 min of recovery. In addition, hematocrit and plasma norepinephrine (NE) were measured. From baseline to 5 min of EX, there were significant increases in LV longitudinal strain (−23.20 ± 0.87 to −27.63 ± 1.07%; P < 0.01), strain rate (−1.50 ± 0.15 to −2.08 ± 0.14 s−1; P < 0.01), and EF (56.3 ± 2.2 to 77.1 ± 1.0%; P < 0.05) with continued increases by both at 30 min of exercise vs. SV, EDV, and ESV, which remained constant. After 120 min of EX, HR and NE increased further with reductions in SV, cardiac output, and systolic blood pressure without changes in strain or strain rate. EDV decreased after 120 min of EX (−9.2- vs. 30-min value; P = 0.05) along with a hemoconcentration (baseline = 41.3 ± 1.0 vs. EX = 45.1 ± 1.2%; P < 0001) and significant reduction in body mass despite a mean fluid consumption of 1.8 ± 0.2 liters throughout EX. After 30 min of recovery, LV longitudinal strain was depressed relative to baseline (−23.20 ± 0.87 to −19.57 ± 1.21%; P < 0.01). The reduction in LV SV during prolonged EX occurred without changes in the LV contractile state and is likely secondary to reduced LV preload. A reduction in LV contractility despite a reduced afterload following exercise may be due to factors unique to the recovery period and do not appear to contribute to a reduction in SV during prolonged exercise.

Effect of External Constraint on the Index of Myocardial Performance in a Canine Model of Left Ventricular Dysfunction

BACKGROUND

With left ventricular (LV) dysfunction, it is not clear how alterations in external constraint influence the index of myocardial performance (IMP). We have previously demonstrated that pericardial constraint is a factor in the production of the restrictive filling pattern. We hypothesized that altering pericardial constraint by changing intracardiac volume or removing the pericardium would produce similar directional changes in LV ejection time (LVET) and isovolumic relaxation time (IRT) resulting in minimal IMP changes.

METHODS

We studied 13 canines with chronic moderate LV dysfunction. LV pressures, transmitral and transaortic Doppler were obtained prior to and following pericardiectomy (PECT) with alterations of intracardiac volume, using inferior vena caval occlusion (IVCO) and volume loading.

RESULTS

With an intact pericardium, IVCO reduced LV size, LV end diastolic pressure (LVEDP), and increased deceleration time (all P < 0.05) but did not affect IMP. Volume loading increased LV size, LVEDP, and shortened deceleration time (all P < 0.05). LVET and IRT lengthened (P < 0.05), and IMP declined (0.58 +/- 0.24 to 0.52 +/- 0.13, P < 0.05). Following PECT, IVCO reduced LV volumes and LVEDP (P < 0.05), but did not change IMP. Volume loading increased LV size, stroke volume, and LVEDP (all P < 0.05). IMP declined (0.57 +/- 0.13 vs 0.51 +/- 0.14, P < 0.05) due to an increase in both LVET and IRT (P < 0.05). Comparison of stages prior to and following PECT revealed an increased LVET and stroke volume (P < 0.05) but a similar IMP.

CONCLUSION

Increases in intracardiac volume associated with elevated LVEDP resulted in reduced IMPs. Pericardiectomy increases LV volumes, stroke volume, and LVET but did not influence IMP.

Concurrent expansion of plasma volume and left ventricular end-diastolic volume in patients after rapid infusion of 5% albumin and lactated Ringer's solution

STUDY OBJECTIVE

To examine the effects of plasma volume expansion on plasma volume, left ventricular end-diastolic volume (LVEDV), and cardiac index (CI) after rapid fluid infusion, as knowledge of the degree of concordance between plasma and cardiac preload expansion could optimize LVEDV expansion without administering excessive fluid.

DESIGN

Randomized, double-blinded study.

SETTING

Academic community hospital.

PATIENTS

20 patients undergoing elective coronary artery bypass surgery.

INTERVENTIONS

Patients were administered either 5% albumin (5 mL/kg) or lactated Ringer's solution (25 mL/kg) over 30 minutes, just before incision.

MEASUREMENTS

Serial measurements of plasma volume, LVEDV by transesophageal echocardiography, and CI were recorded.

MAIN RESULTS

Albumin expanded plasma volume and LVEDV to a similar degree (11.3% and 13.2%). In contrast, lactated Ringer's solution increased plasma volume more than LVEDV (21.7% vs 14.4%; P = 0.0005). Increased LVEDV significantly but poorly correlated with increased CI (r(2) = 0.2, P < 0.0001) for both fluids. However, LVEDV expansion was brief and returned to baseline or less within 30 minutes for both fluids despite continued plasma volume expansion and increased CI. Correspondingly, rates of decline from peak expansion were significantly faster for LVEDV than plasma volume expansion for both albumin (-1.9% + 1.9%/min vs -0.1% + 0.1%/min; P = 0.0008) and lactated Ringer's (-1.1% + 0.8%/min vs -0.4% + 0.2%/min; P = 0.006).

CONCLUSIONS

Intravenous fluids increased LVEDV to a lesser extent and duration than did plasma volume expansion. Monitoring of LVEDV was a poor guide for fluid administration to maximize CI.

Ratio of Early Transmitral Velocity to Lateral Mitral Annular Early Diastolic Velocity Has the Best Correlation With Wedge Pressure Following Cardiac Surgery

BACKGROUND

Although previous investigators reported that mitral annular velocity predicts mean pulmonary capillary wedge pressure (PCWP), it is unknown whether the lateral or septal mitral annular velocity more faithfully predicts PCWP after cardiac surgery.

METHODS AND RESULTS

To assess the effect of cardiac surgery on the predictive values for PCWP by measuring mitral annular velocity, 52 consecutive patients undergoing cardiac surgery were studied. All patients underwent transthoracic echocardiography and right-sided cardiac catheterization both before and after surgery. The peak early diastolic velocity of transmitral flow (E) was measured by pulsed-wave Doppler and the peak early diastolic velocities of the lateral (LEa) and septal (SEa) mitral annulus by pulsed-wave tissue Doppler imaging. The ratios of E to LEa (E/LEa) and SEa (E/SEa) were calculated. Immediately after echocardiography, PCWP was measured using a balloon-tipped pulmonary artery catheter. After surgery, LEa was significantly increased (6.4+/-2.7 vs 8.6+/-3.3 cm/s, p<0.001), but SEa was unchanged (6.0+/-2.5 vs 5.5+/-2.3 cm/s, p=0.09). E/LEa correlated well with PCWP both before and after surgery (r=0.79 and r=0.69, respectively, p<0.001). Although E/SEa correlated well before surgery (r=0.67, p<0.001), it correlated only weakly after surgery (r=0.44, p<0.01).

CONCLUSIONS

E/LEa has the best correlation with PCWP both before and after cardiac surgery and may be more useful than E/SEa in the noninvasive estimation of PCWP.

Point of care ultrasound for basic haemodynamic assessment: novice compared with an expert operator

Miniaturization of ultrasound equipment has led to the development of hand-held echocardiography devices suitable for bedside evaluation of cardiac function. Basic assessment of the haemodynamic state can be performed using a limited transthoracic echocardiography examination. This study evaluated a third generation device (SonoSite Titan) used by novice and expert operators. Limited transthoracic examination was performed on 30 healthy volunteers by an expert and a novice operator. The novice had performed 10 studies prior to data accrual. Agreement analysis was performed using weighted least products regression and Bland-Altman analysis. Acceptable results for the novice were achieved following 20 studies (including practice sessions) for basic haemodynamic assessment and following 40 studies for all measured parameters. The SonoSite Titan is acceptable for basic transthoracic measurements to determine the basic haemodynamic state and cardiac output measurements. We recommend a minimum of 20 training studies for novice operators prior to clinical use.

Abnormal Septal Motion Affects Early Diastolic Velocities at the Septal And Lateral Mitral Annulus, and Impacts on Estimation of the Pulmonary Capillary Wedge Pressure

Abnormal motion of the interventricular septum (ASM), seen post cardiac operation, with left bundle branch block or right ventricular pacing, may affect septal mitral annular motion and correlation of the ratio between the velocity of early diastolic mitral inflow and the early diastolic mitral annular velocity (E/Ea) with pulmonary capillary wedge pressure (PCWP). We examined the effect of ASM on the relationship between E/Ea and E/Vp (propagation velocity of mitral inflow) ratios and PCWP in adult patients in the intensive care unit (14 with normal septal motion [NSM], 36 with ASM) undergoing echocardiography and pulmonary artery catheterization. E/Ea correlated well with PCWP during NSM ( r = 0.86 lateral annulus, r = 0.75 septal annulus), but poorly during ASM ( r = 0.36 lateral annulus, r = 0.39 septal annulus). E/Vp correlated poorly with PCWP ( r = 0.05 NSM, r = 0.17 ASM). For patients who are critically ill, E/Vp ratios poorly estimate PCWP. During NSM, E/Ea ratios measured at the lateral or septal annulus correlate well with PCWP. ASM affects E/Ea ratios at both the septal and lateral annulus, making E/Ea ratios unreliable for estimating PCWP in this group.

Analysis of diastolic function in patients undergoing aortic aneurysm repair and impact on hemodynamic response to aortic cross-clamping

OBJECTIVES

The purpose of this study was to analyze left ventricular diastolic function in patients undergoing aortic aneurysm repair and to investigate the effects of laparotomy and aortic cross-clamping on diastolic function.

DESIGN

Prospective clinical study.

SETTING

University hospital.

PARTICIPANTS

Forty-five consecutive patients undergoing open aortic aneurysm repair.

INTERVENTIONS

Left ventricular diastolic function and hemodynamic variables were evaluated using transesophageal Doppler echocardiography and a pulmonary artery catheter at baseline, after laparotomy, and at 1 and 10 minutes after cross-clamping. Diastolic function was determined by Doppler derivatives of mitral inflow (E/A ratio, deceleration time of early inflow) and pulmonary venous flow (S/D ratio).

MEASUREMENTS AND MAIN RESULTS

Twenty of 39 patients revealed signs of diastolic dysfunction at baseline. Of these 20 patients, 14 displayed delayed relaxation and 6 displayed a pseudonormal filling pattern. Patients with pseudonormal filling exhibited a lower stroke volume (p = 0.02) and cardiac index (p < 0.01) in comparison to patients with normal diastolic function. Laparotomy was associated with an improvement of diastolic function in 9 of 20 patients with preexisting diastolic dysfunction. Only 3 patients suffered impairment of diastolic function after cross-clamping. The hemodynamic response to cross-clamping did not differ between patients with normal and abnormal diastolic function.

CONCLUSIONS

About 50% of patients undergoing aortic aneurysm repair exhibit signs of diastolic dysfunction. The majority of these patients showed delayed relaxation. Patients with pseudonormal filling displayed a significantly lower cardiac index. Laparotomy resulted in an improvement in diastolic function in about half of patients with preexisting diastolic dysfunction. The effects of cross-clamping on diastolic function are minimal.

Assessing fluid responsiveness during open chest conditions

BACKGROUND

Measurement of ventilation-induced left ventricular stroke volume variations (SVV) or pulse pressure variations (PPV) is useful to optimize preload in patients after cardiac surgery. The aim of this study was to investigate the ability of SVV and PPV measured by arterial pulse contour analysis to assess fluid responsiveness in patients undergoing coronary artery bypass surgery during open-chest conditions.

METHODS

We studied 22 patients immediately after midline sternotomy. We determined SVV, PPV, left ventricular end-diastolic area index by transoesophageal echocardiography, global end-diastolic volume index and cardiac index by thermodilution before and after removal of blood 500 ml and after volume substitution with hydroxyethyl starch 6%, 500 ml.

RESULTS

Blood removal resulted in a significant increase in SVV from 6.7 (2.2) to 12.7 (3.8)%. PPV increased from 5.2 (2.5) to 11.9 (4.6)% (both P<0.001). Cardiac index decreased from 2.9 (0.6) to 2.3 (0.5) litres min(-1) m(-2) and global end-diastolic volume index decreased from 650 (98) to 565 (98) ml m(-2) (both P<0.025). Left ventricular end-diastolic area index did not change significantly. After fluid loading SVV decreased significantly to 6.8 (2.2)% and PPV decreased to 5.4 (2.1)% (both P<0.001). Concomitantly, cardiac index increased significantly to 3.3 (0.5) litres min(-1) m(-2) (P<0.001) and global end-diastolic volume index increased significantly to 663 (104) ml m(-2) (P<0.005). Left ventricular end-diastolic area index did not change significantly. We found a significant correlation between the increase in cardiac index caused by fluid loading and SVV as well as PPV before fluid loading (SVV, R=0.74, P<0.001; PPV, R=0.61, P<0.005). No correlations were found between values of global end-diastolic volume index or left ventricular end-diastolic area index before fluid loading and the increase in cardiac index.

CONCLUSION

Measurement of SVV or PPV allows assessment of fluid responsiveness in hypovolaemic patients under open-chest and open-pericardium conditions. Thus, measuring heart-lung interactions may improve haemodynamic management during surgical procedures requiring mid-line sternotomy.

Left Ventricular Diastolic Performance in Neonates

BACKGROUND

The left ventricular (LV) diastolic performance of infants who were in a stable post-treatment condition in the neonatal intensive care unit was evaluated using echocardiography.

METHODS AND RESULTS

The study group comprised 55 infants (Stable infant group, SI) and the parameters of LV performance were: LV propagation velocity (Vp) by color M-mode Doppler echocardiography (CMD), peak E wave, peak A wave, and the E/A ratio of transmitral flow. In a second set of measurements, a subset of 10 infants (patent ductus arteriosus (PDA) infant group, PI) were evaluated for LV diastolic performance during closure of PDA. The mean Vp in the SI was 27.2+/-7.3 cm/s and a positive correlation was observed between Vp and gestational age (r = 0.477, p = 0.0002). In the PI, Vp did not change significantly during closure of the PDA (from 23.3+/-8.2 cm/s to 27.5+/-8.4 cm/s); however, the E/Vp ratio decreased significantly with closure (from 3.14+/-0.83 to 2.12+/-0.68, p = 0.0051).

CONCLUSION

The measurement of Vp by CMD can be considered a parameter for the evaluation of LV diastolic performance, even in the neonatal period. The LV diastolic performance of the infant is maintained from immediately after birth to spontaneous closure of the PDA.