Biventricular diastolic filling patterns after coronary artery bypass graft surgery

Managing Diastolic Dysfunction Perioperatively

Preoperative cardiac evaluation is a cornerstone of the practice of anesthesiology. This consists of a thorough history and physical attempting to elucidate signs and symptoms of heart failure, angina or anginal equivalents, and valvular heart disease. Current guidelines rarely recommend preoperative echocardiography in the setting of an adequate functional capacity. Many patients may have poor functional capacity and/or have medical history such that echocardiographic data is available for review. Much focus is often placed on evaluating major valvular abnormalities and systolic function as measured by ejection fraction, but a key impactful component is often overlooked-diastolic function. A diagnosis of diastolic heart failure is an independent predictor of mortality and is not uncommon in patients with normal systolic function. This narrative review addresses the clinical relevance and management of diastolic dysfunction in the perioperative setting.

Myocardial protection: a forgotten modality

The goals of a cardiac surgical procedure are both technical excellence and complete protection of cardiac function. Cardioplegia is used almost universally to protect the heart and provide a quiet bloodless field for surgical accuracy. Yet, despite the importance of myocardial protection in cardiac surgery, manuscripts or dedicated sessions at major meetings on this subject have become relatively rare, as though contemporary techniques now make them unnecessary. Nevertheless, septal dysfunction and haemodynamic support (inotropes, intra-aortic balloon pump, assist devices) are common in postoperative patients, indicating that myocardial damage following cardiac surgery is still prevalent with current cardioplegic techniques and solutions. This article first describes why cardiac enzymes and septal function are the ideal markers for determining the adequacy of myocardial protection. It also describes the underappreciated consequences of postoperative cardiac enzyme release or septal dysfunction (which currently occurs in 40-80% of patients) from inadequate protection, and how they directly correlate with early and especially late mortality. Finally, it reviews the various myocardial protection techniques available to provide a detailed understanding of the cardioplegic methods that can be utilized to protect the heart. This will allow surgeons to critically assess their current method of protection and, if needed, make necessary changes to provide their patients with optimal protection.

Comprehensive Comparisons among Inotropic Agents on Mortality and Risk of Renal Dysfunction in Patients Who Underwent Cardiac Surgery: A Network Meta-Analysis of Randomized Controlled Trials

Several kinds of inotropes have been used in critically ill patients to improve hemodynamics and renal dysfunction after cardiac surgery; however, the treatment strategies for reducing mortality and increasing renal protection in patients who underwent cardiac surgery remain controversial. Therefore, we performed a comprehensive network meta-analysis to overcome the lack of head-to-head comparisons. A systematic database was searched up to 31 December 2020, for randomized controlled trials that compared different inotropes on mortality outcomes and renal protective effects after cardiac surgery. A total of 29 trials were included and a frequentist network meta-analysis was performed. Inconsistency analyses, publication bias, and subgroup analyses were also conducted. Compared with placebo, use of levosimendan significantly decreased the risks of mortality (odds ratio (OR): 0.74; 95% confidence interval (CI): 0.56–0.97) and risk of acute renal injury (OR: 0.61; 95% CI: 0.45–0.82), especially in low systolic function patients. Use of levosimendan also ranked the best treatment based on the P-score (90.1%), followed by placebo (64.5%), milrinone (49.6%), dopamine (49.5%), dobutamine (29.1%), and fenoldopam (17.0%). Taking all the available data into consideration, levosimendan was a safe renal-protective choice for the treatment of patients undergoing cardiac surgery, especially for those with low systolic function.

Left Atrial Strain as a Single Parameter to Predict Left Ventricular Diastolic Dysfunction and Elevated Left Ventricular Filling Pressure in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

OBJECTIVE

Left ventricular diastolic dysfunction (LVDD) is very common among patients undergoing cardiac surgery and is associated with increased mortality and morbidity. The present study tested the hypothesis of whether left atrial strain (LAS) can be used as a single parameter to predict LVDD (per 2016 LVDD evaluation guidelines) and elevated left ventricular filling pressure (LVFP) (ie, LVDD grades II and III) in patients scheduled for off-pump coronary artery bypass grafting (OPCABG) surgery.

DESIGN

A prospective observational study.

SETTINGS

Tertiary-care level hospital.

PARTICIPANTS

The study comprised 60 patients undergoing elective OPCABG.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Transthoracic echocardiography was performed within 24 hours of surgery by an anesthesiologist. LVDD was graded per American Society of Echocardiography/European Association of Cardiovascular Imaging recommendations for 2016 LVDD guidelines. Left atrial (LA) function was evaluated using two-dimensional strain measurements obtained with the speckle-tracking echocardiography technique. Receiver operating characteristic curves were constructed, and the area under the curve was derived for the prediction of elevated LVFP by LAS. Fourteen (23.3%) patients had elevated LVFP. Global LA reservoir strain (LAS_r) reduced significantly as the LVDD grade worsened (28.9% ± 8.3%, 21.8% ± 7.2%, 15.6% ± 4.5% and 11.9% ± 1.3%, respectively, for normal LV diastolic function and grades I, II, and III LVDD; p < 0.0001). Similar trends were noted for other components of LAS; namely, global LA conduction, global LA contraction strain, and LAS rate. The ability to predict high LVFP with LAS_r was statistically significant, with an area under the receiver operating characteristic curve of 0.92 (confidence interval 0.82-0.97; p < 0.001), and a Youden's index for LAS_r of 19% was obtained with 85.71% sensitivity and 84.78% specificity. The ability of LAS and its components to predict increased LVFP in various subpopulations (normal v reduced ejection fraction) yielded statistically significant results.

CONCLUSIONS

In patients scheduled for OPCABG, cardiac anesthesiologists successfully could measure LAS with speckle-tracking echocardiography in the preoperative period. LAS as a single parameter was significantly associated with the grade of LVDD. LAS_r decreased significantly with worsening grade of LVDD. Furthermore, an LAS_r value <19% significantly predicted a high LVFP, and LAS_r predicted high LVFP in both preserved and reduced ejection fraction equally well.

The effect of milrinone on mortality in adult patients who underwent CABG surgery: a systematic review of randomized clinical trials with a meta-analysis and trial sequential analysis

Background

As an inodilator, milrinone is commonly used for patients who undergo coronary artery bypass graft (CABG) surgery because of its effectiveness in decreasing the cardiac index and mitral regurgitation. The aim of this study was to perform a systematic review and meta-analysis of existing studies from the past 20 years to evaluate the impact of milrinone on mortality in patients who undergo CABG surgery.

Methods

We performed a systematic literature search on the application of milrinone in patients who underwent CABG surgery in studies published between 1997 and 2017 in BioMed Central, PubMed, EMBASE, and the Cochrane Central Register. The included studies evaluated milrinone groups compared to groups receiving either placebo or standard treatment and further compared the systemic administration.

Results

The network meta-analysis included 723 patients from 16 randomized clinical trials. Overall, there was no significant difference in mortality between the milrinone group and the placebo/standard care group when patients underwent CABG surgery. In addition, 9 trials (with 440 randomized patients), 4 trials (with 212 randomized patients), and 10 trials (with 470 randomized patients) reported that the occurrence of myocardial infarction (MI), myocardial ischemia, and arrhythmia was lower in the milrinone group than in the placebo/standard care group. Between the milrinone treatment and placebo/standard care groups, the occurrence of myocardial infarction, myocardial ischemia, and arrhythmia was significantly different. However, the occurrence of stroke and renal failure, the duration of inotropic support (h), the need for an intra-aortic balloon pump (IABP), and mechanical ventilation (h) between these two groups showed no differences.

Conclusions

Based on the current results, compared with placebo, milrinone might be unable to decrease mortality in adult CABG surgical patients but can significantly ameliorate the occurrence of MI, myocardial ischemia, and arrhythmia. These results provide evidence for the further clinical application of milrinone and of therapeutic strategies for CABG surgery. However, along with milrinone application in clinical use, sufficient data from randomized clinical trials need to be collected, and the potential benefits and adverse effects should be analyzed and reevaluated.

[A. N. Bakoulev Scientific Center for Cardiovascular Surgery]

OBJECTIVE

to assess dynamics of diastolic function for detection of development of diastolic dysfunction (DD) and it's causes, to evaluate the effect of DD on prognosis in the postoperative period in patients with acquired heart diseases.

MATERIALS AND METHODS

We included in this study 112 patients with aortic and mitral valve diseases (90 men, 22 women, median age 51 [35; 57] years). All patients underwent echocardiography (echo), tissue Doppler, speckle tracking echo prior to surgery, in the early postoperative period (8-14 days) and in 12-36 months after surgery. In 28 patients dynamic contrast-enhanced magnetic resonance imaging was also performed. Patients were divided into groups according to prognosis: group 0 - without complications; group 1 - with postoperative heart failure (HF) and preserved left ventricular ejection fraction (EF); group 2 - with HF and EF &lt;45 %. The following parameters were used for identifying left ventricular (LV) DD: septal velocity es &lt;7 cm / sec, lateral el &lt;10 cm / sec, average E / e ratio &gt;14, left atrial (LA) volume index &gt;34 ml / m2, peak tricuspid regurgitation velocity &gt;2.8 m / sec.

RESULTS

Initially diastolicLV function was normal in 34 of 112 patients (30.4 %), in early postoperative period DD emerged in 9 (26.5 %) of these patients. The appearance of LV DD was associated with decrease of septal es immediately after surgery and its subsequent progressive decline in the long-term postoperative period from 8.5±0.71 to 4.6 ±0.53 cm / sec (p=0.005). Worsening of diastolic function and lowering of septal velocity was detected namely in patients with presence of fibrosis. In the group of other patients in whom fibrosis was not studied and the degree of DD increased there was a transient decrease of lateral el (from 10.2±3.1 to 7.5±2.43 cm / sec, p=0.035) and an increase of the E / el (from 10.53±4.07 to 14.5±5.23, p=0.05) in the early period after the operation. There were no correlations between DD and LV EF,LV volumes, and development of arrhythmias. The prognostic model for DD included average longitudinal deformation of LA (global LA longitudinal strain) and E / e ratio on the tricuspid lateral annular velocity.

CONCLUSIONS

Appearance of DD in postoperative period after correction of acquired heart defects was due to damage of the septal diastolic function which correlated with fibrosis and was indicative of inadequate myocardial protection. The model of development of heart failure with normal EF after operation was designed.

MK5 haplodeficiency decreases collagen deposition and scar size during post-myocardial infarction wound repair

MK5 is a protein serine/threonine kinase activated by p38, ERK3, and ERK4 MAPKs. MK5 mRNA and immunoreactivity are detected in mouse cardiac fibroblasts, and MK5 haplodeficiency attenuates the increase in collagen 1-α1 mRNA evoked by pressure overload. The present study examined the effect of MK5 haplodeficiency on reparative fibrosis following myocardial infarction (MI). Twelve-week-old MK5^+/- and wild-type littermate (MK5^+/+) mice underwent ligation of the left anterior descending coronary artery (LADL). Surviving mice were euthanized 8 or 21 days post-MI. Survival rates did not differ significantly between MK5^+/+ and MK5^+/- mice, with rupture of the LV wall being the primary cause of death. Echocardiographic imaging revealed similar increases in LV end-diastolic diameter, myocardial performance index, and wall motion score index in LADL-MK5^+/+ and LADL-MK5^+/- mice. Area at risk did not differ between LADL-MK5^+/+ and LADL-MK5^+/- hearts. In contrast, infarct size, scar area, and scar collagen content were reduced in LADL-MK5^+/- hearts. Immunohistochemical analysis of mice experiencing heart rupture revealed increased MMP-9 immunoreactivity in the infarct border zone of LADL-MK5^+/- hearts compared with LADL-MK5^+/+. Although inflammatory cell infiltration was similar in LADL-MK5^+/+ and LADL-MK5^+/- hearts, angiogenesis was more pronounced in the infarct border zone of LADL-MK5^+/- mice. Characterization of ventricular fibroblasts revealed reduced motility and proliferation in fibroblasts isolated from MK5^-/- mice compared with those from both wild-type and haplodeficient mice. siRNA-mediated knockdown of MK5 in fibroblasts from wild-type mice also impaired motility. Hence, reduced MK5 expression alters fibroblast function and scar morphology but not mortality post-MI. NEW & NOTEWORTHY MK5/PRAK is a protein serine/threonine kinase activated by p38 MAPK and/or atypical MAPKs ERK3/4. MK5 haplodeficiency reduced infarct size, scar area, and scar collagen content post-myocardial infarction. Motility and proliferation were reduced in cultured MK5-null cardiac myofibroblasts.

The Sum of Early Diastolic Annulus Velocities in the Mitral and Tricuspid Valve Can Predict Adverse Events After Cardiac Surgery

OBJECTIVES

To assess whether a tissue Doppler imaging (TDI)-based parameter consisting of the sum of early diastolic velocities of the mitral annulus (Me') and tricuspid annulus (Te') can serve as a predictor of adverse outcomes after cardiac surgery.

DESIGN

Prospective, observational study.

SETTING

University hospital.

PARTICIPANTS

The study comprised 100 patients undergoing cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

After anesthetic induction, transesophageal echocardiography was performed to obtain the values of the early transmitral flow velocity (E), Me', and Te'. The primary endpoint was the incidence of postoperative major organ morbidity and mortality (MOMM) events, including death, redo surgery, prolonged ventilation, stroke, sternal infection, and dialysis. Receiver operating characteristic and multivariate logistic analyses were used to examine the prognostic performance of TDI-based parameters for predicting MOMM incidence. The secondary endpoint was the incidence of death or rehospitalization for cardiovascular disease within 1 year post-discharge. TDI-based parameters were measured in 87 of the 100 patients enrolled. Me' plus Te' had better prognostic ability (area under the curve 0.771; threshold 13 cm/s; sensitivity 86.7%; specificity 64.9%) than that of Me' or E to Me' (E/Me')% and was an independent predictor of MOMM (odds ratio 0.45; 95% confidence interval 0.28-0.74, p = 0.001), whereas Me' was not. Lower Me' plus Te' (≤13 cm/s) was associated with a significantly higher incidence and earlier onset of cardiovascular events within 1 year post-discharge (p = 0.012).

CONCLUSIONS

Compared with Me' and E/Me', which traditionally are used for assessing diastolic function, Me' plus Te' showed better prognostic ability for both short- and long-term outcomes of cardiac surgery.

What Is the Heart? Anatomy, Function, Pathophysiology, and Misconceptions

Cardiac dynamics are traditionally linked to a left ventricle, right ventricle, and septum morphology, a topography that differs from the heart's five-century-old anatomic description of containing a helix and circumferential wrap architectural configuration. Torrent Guasp's helical ventricular myocardial band (HVMB) defines this anatomy and its structure, and explains why the heart's six dynamic actions of narrowing, shortening, lengthening, widening, twisting, and uncoiling happen. The described structural findings will raise questions about deductions guiding "accepted cardiac mechanics", and their functional aspects will challenge and overturn them. These suppositions include the LV, RV, and septum description, timing of mitral valve opening, isovolumic relaxation period, reasons for torsion/twisting, untwisting, reasons for longitudinal and circumferential strain, echocardiographic sub segmentation, resynchronization, RV function dynamics, diastolic dysfunction's cause, and unrecognized septum impairment. Torrent Guasp's revolutionary contributions may alter future understanding of the diagnosis and treatment of cardiac disease.

The Critical Importance of Hepatic Venous Blood Flow Doppler Assessment for Patients in Shock

Hepatic venous blood flow can be easily obtained using bedside ultrasound with either transthoracic or transesophageal echocardiography. Six critically ill patients with shock associated with absent or significantly reduced hepatic venous blood flow in the presence of normal or increased pulmonary venous flow are presented. In all these patients, the etiology of shock was secondary to increased resistance to venous return from either an intraabdominal process or through extrinsic or intrinsic occlusion of the proximal inferior vena cava or right atrium. These shock situations are secondary to increased resistance to venous return. Their treatment is highly specific and typically involves a surgical intervention.

Predictors and Clinical Impacts of Aggravated Left Ventricular Diastolic Dysfunction After Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

To determine the predictors of aggravated left ventricular diastolic dysfunction (LVDD) in patients undergoing off-pump coronary artery bypass grafting (OPCAB) and to compare late outcomes according to the aggravated LVDD.

METHODS AND RESULTS

OPCAB was performed in 1,101 patients (2001-2013). LVDD was classified as normal, mild, moderate or severe. Patients were divided into 2 groups: non-aggravated LVDD (group I) and aggravated LVDD (group II). The primary endpoint was aggravation of LVDD. The secondary endpoint was late mortality and morbidity such as major adverse cardiac and cerebrovascular events (MACCE) related to LVDD aggravation postoperatively. There were 894 patients in group I and 207 in group II. Multivariate analysis revealed that preoperative peripheral artery obstructive disease (PAOD) (P=0.04), renal failure (P<0.01), and A' velocity (P<0.01) anticipated aggravated LVDD. The Cox hazards model revealed that aggravated LVDD was a poor prognostic factor for MACCE (P<0.01) and overall survival (P<0.01). The Kaplan-Meier survival curve showed that aggravated LVDD was related to poor late outcomes (freedom from MACCE, P=0.01; overall survival, P<0.01).

CONCLUSIONS

Aggravated LVDD significantly affects late clinical outcomes after OPCAB and preoperative PAOD, renal failure, and A' velocity might be predictors. (Circ J 2016; 80: 1937-1945).

HDL mimetic peptide CER-522 treatment regresses left ventricular diastolic dysfunction in cholesterol-fed rabbits

OBJECTIVES

High-density lipoprotein (HDL) infusions induce rapid improvement of experimental atherosclerosis in rabbits but their effect on ventricular function remains unknown. We aimed to evaluate the effects of the HDL mimetic peptide CER-522 on left ventricular diastolic dysfunction (LVDD).

METHODS

Rabbits were fed with a cholesterol- and vitamin D2-enriched diet until mild aortic valve stenosis and hypercholesterolemia-induced LV hypertrophy and LVDD developed. Animals then received saline or 10 or 30mg/kg CER-522 infusions 6 times over 2weeks. We performed serial echocardiograms and LV histology to evaluate the effects of CER-522 therapy on LVDD.

RESULTS

LVDD was reduced by CER-522 as shown by multiple parameters including early filling mitral deceleration time, deceleration rate, Em/Am ratio, E/Em ratio, pulmonary venous velocities, and LVDD score. These findings were associated with reduced macrophages (RAM-11 positive cells) in the pericoronary area and LV, and decreased levels of apoptotic cardiomyocytes in CER-522-treated rabbits. CER-522 treatment also resulted in decreased atheromatous plaques and internal elastic lamina area in coronary arteries.

CONCLUSIONS

CER-522 improves LVDD in rabbits, with reductions of LV macrophage accumulation, cardiomyocyte apoptosis, coronary atherosclerosis and remodelling.

Right Ventricular Depression After Cardiopulmonary Bypass for Valvular Surgery

OBJECTIVE

To assess if right ventricular (RV) dysfunction is associated with increased mortality after cardiac surgery.

DESIGN

Post-hoc analysis of a single-center double-blind randomized controlled trial.

SETTING

University hospital.

PARTICIPANTS

A total of 120 patients undergoing simple or complex valvular surgery.

INTERVENTIONS

Patients were randomized to receive intravenous amiodarone or placebo intraoperatively. As secondary analysis, patients were divided into those requiring or not requiring postoperative inotropic agents.

MEASUREMENTS AND MAIN RESULTS

After cardiopulmonary bypass (CPB), there were significant increases in heart rate, cardiac index, systolic and mean arterial pressures, central venous pressure and pulmonary capillary wedge pressure with reduction in systemic vascular resistance (p<0.05). Right ventricular end-systolic area became larger in those without inotropes and tricuspid annular plane systolic excursion was reduced in all patients; mitral annular systolic velocities were higher in patients receiving inotropes. Both right- and left-sided Doppler signals were altered significantly after CPB, which may be attributed to increased filling pressure. Inotropic agents were required in 56 patients after CPB (47%). The use of inotropic agents was associated with increased left and right atrial velocities (p<0.05). There were no differences in postoperative complications between groups; however, the number of deaths at 6 years was increased in patients who received inotropes after CPB (p = 0.0247).

CONCLUSIONS

The increases in right-sided dimensions after CPB are associated with reduction in RV function and increased biventricular filling pressure, suggesting worsening biventricular function and interventricular dependence. Inotropic medications were associated with unaltered RV dimensions and increased biatrial activity.

Innovative approaches in the perioperative care of the cardiac surgical patient in the operating room and intensive care unit

Perioperative care for cardiac surgery is undergoing rapid evolution. Many of the changes involve the application of novel technologies to tackle common challenges in optimizing perioperative management. Herein, we illustrate recent advances in perioperative management by focusing on a number of novel components that we judge to be particularly important. These include: the introduction of brain and somatic oximetry; transesophageal echocardiographic hemodynamic monitoring and bedside focused ultrasound; ultrasound-guided vascular access; point-of-care coagulation surveillance; right ventricular pressure monitoring; novel inhaled treatment for right ventricular failure; new approaches for postoperative pain management; novel approaches in specialized care procedures to ensure quality control; and specific approaches to optimize the management for postoperative cardiac arrest. Herein, we discuss the reasons that each of these components are particularly important in improving perioperative care, describe how they can be addressed, and their impact in the care of patients who undergo cardiac surgery.

Acute intraoperative effect of intravenous amiodarone on right ventricular function in patients undergoing valvular surgery

BACKGROUND

Amiodarone is commonly used in the acute care setting. However the acute hemodynamic and echocardiographic effect of intravenous amiodarone administered intraoperatively on right ventricular (RV) systolic and diastolic function using transesophageal echocardiography (TEE) has not been described.

METHODS

The study design was a randomized controlled trial in elective cardiac surgical patients undergoing valvular surgery. Patients received an intravenous loading dose of 300 mg of either amiodarone or placebo in the operating room, followed by an infusion of 15 mg/kg for two days. Hemodynamic profiles, echocardiographic measurement of RV and left ventricular (LV) dimensions, Doppler interrogation of tricuspid and mitral valve, hepatic and pulmonary venous flow combined with tissue Doppler imaging of the tricuspid and mitral valve annulus were obtained before and after bolus.

RESULTS

Although more patients in the placebo group had chronic obstructive lung disease (14 vs 6, p=0.05) and diabetes (14 vs 5; p=0.0244), there was no difference in terms of baseline hemodynamic, 2D and Doppler variables. After bolus, a significant increase in pulmonary artery pressure, central venous pressure and pulmonary vascular resistance index (p<0.05) was observed in the amiodarone group with reduction in systolic to diastolic (S/D) ratio of the hepatic (p=0.0247) and pulmonary venous (p=0.0052) velocity.

CONCLUSION

Acute administration of amiodarone is associated with alteration in RV diastolic properties and has minimal negative inotropic effect on RV systolic function in cardiac surgical patients with valvular disease.

Optimisation of reference genes for gene-expression analysis in a rabbit model of left ventricular diastolic dysfunction

Left ventricular diastolic dysfunction (LVDD) is characterized by the disturbance of ventricle’s performance due to its abnormal relaxation or to its increased stiffness during the diastolic phase. The molecular mechanisms underlying LVDD remain unknown. We aimed to identify normalization genes for accurate gene-expression analysis of LVDD using quantitative real-time PCR (RT-PCR) in a new rabbit model of LVDD. Eighteen rabbits were fed with a normal diet (n = 7) or a 0.5% cholesterol-enriched diet supplemented with vitamin D2 (n = 11) for an average of 14.5 weeks. We validated the presence of LVDD in this model using echocardiography for diastolic function assessment. RT-PCR was performed using cDNA derived from left ventricle samples to measure the stability of 10 genes as candidate reference genes (Gapdh, Hprt1, Ppia, Sdha, Rpl5, Actb, Eef1e1, Ywhaz, Pgk1, and G6pd). Using geNorm analysis, we report that Sdha, Gapdh and Hprt1 genes had the highest stability (M <0.2). By contrast, Hprt1 and Rpl5 genes were found to represent the best combination for normalization when using the Normfinder algorithm (stability value of 0.042). Comparison of both normalization strategies highlighted an increase of natriuretic peptides (Bnp and Anp), monocytes chemotactic protein-1 (Mcp-1) and NADPH oxidase subunit (Nox-2) mRNA expressions in ventricle samples of the hypercholesterolemic rabbits compared to controls (P<0.05). This increase correlates with LVDD echocardiographic parameters and most importantly it molecularly validates the presence of the disease in our model. This is the first study emphasizing the selection of stable reference genes for RT-PCR normalization in a rabbit model of LVDD.

Hemodynamic pressure waveform analysis in predicting fluid responsiveness

OBJECTIVE

To assess the usefulness of central venous pressure (CVP), diastolic right ventricular pressure, and pulmonary capillary wedge pressure (PCWP) waveform analysis in predicting fluid responsiveness.

DESIGN

A prospective observational study.

SETTING

Tertiary care university hospital.

PATIENTS

Forty-four patients undergoing coronary artery bypass grafting.

INTERVENTIONS

Analysis of the a/v wave ratio of the PCWP, CVP, and right ventricular dP/dt to predict an increase in stroke volume >15% after the administration of 500 mL of colloid.

MEASUREMENTS AND MAIN RESULTS

Forty-four patients were enrolled in this study and 7 were excluded. There were 24 responders and 13 nonresponders. No differences in mean CVP and PCWP values between the responders and the nonresponders were found. The only parameter associated with a significant response to volume infusion was the ratio of the a/v waves of the PCWP tracing (p = 0.0001). The performance of the a/v wave ratio>1 of the PCWP tracing in predicting fluid responsiveness was evaluated by constructing a receiver operating characteristic curve. The area under the receiver operating characteristic curve was 0.89 (95% confidence interval, 0.79-0.99; p<0.05).

CONCLUSIONS

The a/v ratio measured on the PCWP tracing is a predictor of fluid responsiveness in patients with preserved left ventricular function undergoing coronary artery bypass grafting.

Perioperative right ventricular dysfunction

PURPOSE OF REVIEW

To evaluate new information on the importance of right ventricular function, diagnosis and management in cardiac surgical patients.

RECENT FINDINGS

There is growing evidence that right ventricular function is a key determinant in survival in cardiac surgery, particularly in patients with pulmonary hypertension. The diagnosis of this condition is helped by the use of specific hemodynamic parameters and echocardiography. In that regard, international consensus guidelines on the echocardiographic assessment of right ventricular function have been recently published. New monitoring modalities in cardiac surgery such as regional near-infrared spectroscopy can also assist management. Management of right ventricular failure will be influenced by the presence or absence of myocardial ischemia and left ventricular dysfunction. The differential diagnosis and management will be facilitated using a systematic approach.

SUMMARY

The use of right ventricular pressure monitoring and the publications of guidelines for the echocardiographic assessment of right ventricular anatomy and function allow the early identification of right ventricular failure. The treatment success will be associated by optimization of the hemodynamic, echocardiographic and near-infrared spectroscopy parameters.

Atorvastatin worsens left ventricular diastolic dysfunction and endothelial dysfunction of epicardial coronary arteries in normocholesterolemic porcine with left ventricular hypertrophy

Statins have pleiotropic effects that can reverse endothelial dysfunction and prevent the development of left ventricular hypertrophy (LVH). The goal of this study was to assess the effect of treatment with atorvastatin on the endothelial dysfunction of epicardial coronary arteries and the development of LVH in a porcine model. LVH was induced through 2 months of aortic banding (AB) of the ascending aorta. Experimental groups were (1) sham untreated: without AB, (2) LVH untreated: with AB, and (3,4) LVH treated: with AB treated with 40 and 80 mg of atorvastatin, respectively, for 60 days, and (5) sham treated: without AB treated with 80 mg of atorvastatin for 60 days. Vascular reactivity studies were performed in organ chambers experiments. NO bioavailability was assessed using cyclic guanosine monophosphate quantification. Oxidative stress levels were measured by quantifying angiotensin II) and nitrite/nitrate levels. LVH and LV diastolic function were evaluated using echocardiography. Atorvastatin decreased endothelium-dependent relaxations and cyclic guanosine monophosphate levels in all treated animals. Angiotensin II levels were increased, whereas nitrite levels were similar among groups (P > 0.05). LV diastolic dysfunction and LVH were significantly greater in all treated animals (P < 0.01). High-density lipoprotein levels and low-density lipoprotein levels were significantly decreased in animals receiving atorvastatin (P < 0.05). In this swine model of LVH, atorvastatin did not prevent LVH development or coronary endothelial dysfunction and resulted in worsening of the LV diastolic dysfunction.

Intraoperative Hemodynamic Instability During and After Separation From Cardiopulmonary Bypass

Every year, more than 1 million patients worldwide undergo cardiac surgery. Because of the aging of the population, cardiac surgery will increasingly be offered to patients at a higher risk of complications. The consequence is a reduced physiological reserve and hence an increased risk of mortality. These issues will have a significant impact on future health care costs because the population undergoing cardiac surgery will be older and more likely to develop postoperative complications. One of the most dreaded complications in cardiac surgery is difficult separation from cardiopulmonary bypass (CPB). When separation from CPB is associated with right-ventricular failure, the mortality rate will range from 44% to 86%. Therefore, the diagnosis and the preoperative prediction of difficult separation from CPB will be crucial to improve the selection and care of patients and to prevent complications for this high-risk patient population.

Left ventricular diastolic dysfunction of the cardiac surgery patient; a point of view for the cardiac surgeon and cardio-anesthesiologist

BACKGROUND

Left ventricular diastolic dysfunction (DD) is defined as the inability of the ventricle to fill to a normal end-diastolic volume, both during exercise as well as at rest, while left atrial pressure does not exceed 12 mm Hg. We examined the concept of left ventricular diastolic dysfunction in a cardiac surgery setting.

MATERIALS AND METHODS

Literature review was carried out in order to identify the overall experience of an important and highly underestimated issue: the unexpected adverse outcome due to ventricular stiffness, following cardiac surgery.

RESULTS

Although diverse group of patients for cardiac surgery could potentially affected from diastolic dysfunction, there are only few studies looking in to the impact of DD on the postoperative outcome; Trans-thoracic echo-cardiography (TTE) is the main stay for the diagnosis of DD. Intraoperative trans-oesophageal (TOE) adds to the management. Subgroups of DD can be defined with prognostic significance.

CONCLUSION

DD with elevated left ventricular end-diastolic pressure can predispose to increased perioperative mortality and morbidity. Furthermore, DD is often associated with systolic dysfunction, left ventricular hypertrophy or indeed pulmonary hypertension. When the diagnosis of DD is made, peri-operative attention to this group of patients becomes mandatory.

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.

Distinct genomic replacements from Lewis correct diastolic dysfunction, attenuate hypertension, and reduce left ventricular hypertrophy in Dahl salt-sensitive rats

BACKGROUND

Hypertension and diastolic heart failure are two common cardiovascular diseases that inflict heavy morbidity and mortality, yet relatively little is understood about their pathophysiology. The identification of quantitative trait loci for blood pressure is important in unveiling the causes of polygenic hypertension. Although Dahl salt-sensitive strain is also an excellent model for the study of diastolic heart failure, virtually nothing is known about the quantitative trait loci determining diastolic heart failure. Diastolic dysfunction often represents the onset of diastolic heart failure.

METHODS

We first characterized the cardiac phenotype of Dahl salt-sensitive strain and normotensive Lewis control rats by echocardiography to ascertain diastolic function. We then analyzed corresponding features of four newly developed and two existing congenic strains, each of which carries a specific chromosome substitution of Dahl salt-sensitive strain by its Lewis homologue and each lowering blood pressure.

RESULTS

Dahl salt-sensitive strain displayed diastolic dysfunction that was rectified in two of six congenic strains, designated as positive congenic strains, which represent the first rodent models exhibiting functional normalization of diastolic dysfunction caused by naturally occurring genetic variants. The two positive congenic strains also showed a reduction in left ventricular mass. In contrast, four of six congenic strains did not change diastolic function despite their blood pressure-lowering effects.

CONCLUSION

Genes present in the replaced chromosome segments of the two positive congenic strains are not commonly known to affect blood pressure, diastolic function or left ventricular mass. Consequently, novel prognostic, diagnostic and therapeutic strategies for hypertensive diastolic heart failure likely emerge from this work.

Baseline regional cerebral oxygen saturation correlates with left ventricular systolic and diastolic function

OBJECTIVE

To evaluate the correlation between baseline cerebral oxygen saturation (ScO(2)) and cardiac function as assessed by pulmonary artery catheterization and transesophageal echocardiography (TEE).

DESIGN

A retrospective study.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Cardiac surgery patients.

MEASUREMENTS AND RESULTS

Patients undergoing cardiac surgery with bilateral recording of their baseline ScO(2) using the INVOS 4100 (Somanetics, Troy, MI) were selected. A pulmonary artery catheter was used to obtain their hemodynamic profile. Left ventricular (LV) systolic and diastolic function was evaluated by TEE, after the induction of anesthesia, using standard criteria. A model was developed to predict ScO(2). A total of 99 patients met the inclusion criteria. There were significant correlations between mean ScO(2) values and central venous pressure (CVP) (r = -0.31, p = 0.0022), pulmonary capillary wedge pressure (r = -0.25, p = 0.0129), mean pulmonary artery pressure (MPAP) (r = -0.24, p = 0.0186), mean arterial pressure/MPAP ratio (r = 0.33, p = 0.0011), LV fractional area change (<35, 35-50, and >or=50, p = 0.0002), regional wall motion score index (r = -0.27, p = 0.0062), and diastolic function (p = 0.0060). The mean ScO(2) had the highest area under the receiver operating characteristic curve (0.74; confidence interval, 0.64-0.84) to identify LV systolic dysfunction. A model predicting baseline ScO(2) was created based on LV systolic echocardiographic variables, CVP, sex, mitral valve surgery, and the use of beta-blocker (r(2) = 0.42, p < 0.001).

CONCLUSION

Baseline ScO(2) values are related to cardiac function and are superior to hemodynamic parameters at predicting LV dysfunction.

The effect of heart rate on tricuspid annular velocities in cardiac surgical patients with atrial fibrillation

OBJECTIVES

Tricuspid annular isovolumic acceleration is a load-independent measure of contractility, but its relationship to heart rate is unknown in humans. The authors investigated the effect of heart rate on measurements of isovolumic acceleration and systolic wave velocities in postoperative cardiac surgical patients with atrial fibrillation.

DESIGN

This was a prospective observational study.

SETTING

Single-university hospital setting.

PARTICIPANTS

Postoperative cardiac surgical patients with atrial fibrillation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Lateral tricuspid isovolumic acceleration and peak systolic wave velocity were measured using color-tissue Doppler. The corresponding heart rate was calculated from the preceding R-R interval. Regression analysis was used to assess the relationship between heart rate and tricuspid annular velocity. A heart rate threshold value was determined at which the tissue Doppler variables were significantly altered by heart rate. Seven hundred fifteen beats in 15 patients were analyzed. There was a positive linear correlation between isovolumic acceleration and heart rate and a negative polynomial correlation between the systolic wave and heart rate. A significant reduction in systolic wave velocity occurred at heart rates greater than 110 beats/min.

CONCLUSIONS

In this patient population, isovolumic acceleration significantly increased with increasing heart rate. Tachycardia-induced preload alterations and impaired force-frequency responses may have been responsible for the decrease in systolic wave velocities.

Inhaled milrinone: a new alternative in cardiac surgery?

The administration of milrinone through inhalation has been studied in only a few animal and human studies. Compared to the intravenous administration, inhaled milrinone has been shown to reduce pulmonary artery pressure without systemic hypotension. Therefore, this approach could represent an alternative to nitric oxide. This current state of knowledge of intravenous and inhaled milrinone is presented and summarized.