Left Heart Performance Research Articles

Biventricular Repair in Borderline Left Hearts: Insights From Cardiac Magnetic Resonance Imaging

BackgroundCardiac magnetic resonance imaging (CMR) may augment 2-dimensional (2D) echocardiography in decision-making for biventricular repair in borderline hypoplastic left hearts. ObjectivesThis study evaluates: 1) the relationship between 2D echocardiography and CMR; 2) imaging variables affecting assignment to biventricular vs non-biventricular management; and 3) variables affecting transplant-free biventricular survival. MethodsWe reviewed clinical, echocardiographic, and CMR data in 67 infants, including CMR-determined ascending aortic (AAo) flow and comparable left ventricular end-diastolic volume indexed (LVEDVi) by 2D-echocardiography and CMR. ResultsTreatment assignment to biventricular repair was either direct (BV, n = 45) or with a bridging hybrid procedure (H1-BV, n = 12). Echocardiographic LVEDVi was <20 mL/m2 in 83% of biventricular repair infants and underestimated CMR-LVEDVi by 16.8 mL/m2. AAo flows had no/weak correlation with aortic and mitral valve z-scores or LVEDVi. AAo flows differed between BV, H1-BV, and single-ventricle groups (median): 2.1, 1.7, and 0.7 L/min/m2, respectively. Important variables for treatment assignment were presence of endocardial fibroelastosis, AAo flow, and mitral valve z-score. Biventricular repair was achieved in 54. The median follow-up was 8.0 (0.1-16.4) years. Transplant-free biventricular survival was 96%, 82%, and 77% at 1, 5, and 10 years, respectively. Patients without aortic coarctation repair were at higher risk of death, transplantation, or single-ventricle conversion (HR: 54.3; 95% CI: 6.3-47.1; P < 0.001) during follow-up. AAo flow had a smaller nonlinear effect with hazard ratio increasing at lower flows. ConclusionsHistorical 2D echocardiographic criteria would have precluded many patients from successful biventricular repair. AAo flow, an integrative index of left heart performance, was important in assigning patients to a biventricular circulation and affected survival. Biventricular survival was strongly associated with the need for aortic coarctation repair.

Hearts from Donations after Circulatory Death (DCD) Donors - Ischaemic Post-Conditioning Significantly Improves Recovery of Cardiac Function Following Warm Ischaemia in A Porcine Model

Introduction: Utilisation of hearts from Donations after circulatory death (DCD) donors has been limited by fear of warm ischaemic damage. We aim to investigate the impact of varying periods of warm ischaemia on cardiac function in DCD hearts, and evaluate ischaemic post-conditioning strategies to limit warm ischaemic injury. Methods: Utilising a porcine DCD model, 3 warm ischaemic time (WIT) periods were evaluated. All hearts were antegrade flushed with Celsior solution after the designated period of warm ischaemia. Ischaemic post-conditioning was affected with the supplementation of Celsior with glyceryl trinitrate (GTN), erythropoietin (EPO), and zoniporide - this approach has been studied extensively in our laboratory1. (table 1)Hearts were explanted onto an isolated working heart circuit. Left heart performance was assessed for 4 hours - functional assessment (Cardiac Output, Coronary Flow, Left Atrial Pressure (LAP) vs Aortic Flow (AF) challenge), metabolic recovery (pH, lactate, myocardial oxygen consumption), and biochemical parameters (troponin, LDH) were evaluated. Results: When compared with control hearts, Group 1 hearts showed complete functional recovery, Group 2 had partial recovery and Group 3 had no recovery. Cardiac Output was inferior with Group 2 hearts (graph 1). The increase in AF in response to increased LAP was significantly blunted for Group 2 (p=0.05), when compared with control and Group 1. Group 2 hearts also remained more acidotic (p=0.03), had higher lactate levels (p=0.03), greater troponin release (p=0.03) and had non-significant trends towards higher LDH levels than control or Group 1 hearts. Following the supplementation of the preservation flush for 30 minute warm ischaemia hearts (Group 4) there was a significantly improved functional and biochemical recovery when compared with group 2 hearts (unsupplemented 30 minute warm ischaemia hearts). Comparing group 2 and group 4, group 4 had superior Cardiac Output (p < 0.01, see graph 1), higher coronary flows (p < 0.01), superior performance in the AF vs LAP challenge (p = 0.03), and decreased troponin release (p=0.05).Figure: [Graph 1]Conclusion: Hearts with a WIT of less than 20 minutes demonstrate excellent recovery, supporting the potential for DCD hearts in transplantation. The detrimental effects of warm ischaemia become evident beyond 20 minutes - here, ischaemc post-conditioning strategies aimed at mitigating ischaemia-reperfusion injury significantly improve cardiac recovery. With the utilization of such strategies in preserving cardiac function following 30 minutes of warm ischaemia, the potential for translation to clinical DCD heart transplantation is greatly strengthened and warrants further investigation.

OP22.07: Evaluation of right and left heart performance in small‐for‐gestational‐age fetuses with TAPSE and MAPSE

Gestational age at scan (weeks) 35.4 ± 2.9 36.7 ± 3.0 36.2 ± 3.2 0.094 Feto-placental Doppler (z-scores) Umbilical artery pulsatility index −0.02 ± 0.54 −0.02 ± 0.60 0.16 ± 0.53 0.166 Middle cerebral artery pulsatility index 0.54 ± 0.97 0.18 ± 0.71 0.44 ± 0.94 0.146 Cerebroplacental ratio 0.21 ± 1.21 −0.06 ± 1.13 −0.06 ± 1.23 0.362 Fetal cardiac morphometry Cardiothoracic Ratio 0.28 ± 0.05 0.32 ± 0.06* 0.34 ± 0.06* <0.001 Left Sphericity Index 1.83 ± 0.32 1.67 ± 0.25* 1.59 ± 0.33* <0.001 Fetal cardiac function (z-scores) Left myocardial performance Index 0.04 ± 0.59 0.99 ± 1.09* 1.25 ± 1.09* <0.001 Tricuspid annular plane systolic excursion −0.74 ± 0.79 −1.53 ± 0.94* −1.59 ± 0.85* <0.001 Septal annular early diastolic peak velocity (E’) 0.79 ± 1.07 −0.49 ± 1.18* −0.51 ± 1.23* <0.001 Septal annular systolic peak velocity (S’) 0.88 ± 1.11 −0.33 ± 0.98* −0.39 ± 1.06* <0.001

Albumin Augmentation Improves Condition of Guinea Pig Hearts After 4 hr of Cold Ischemia

Major causes of death after heart transplantation are right ventricular pump failure and, chronically, cardiac allograft vasculopathy. Traditional preservation techniques focus on immediate cardioplegia, without particularly considering vascular demands. Recently, the endothelial surface layer, composed of the endothelial glycocalyx and plasma proteins, was discovered to play a major role in vascular barrier function, edema formation, and leukocyte-to-endothelial interaction. The impact of augmenting a traditional preservation solution with plasma colloid albumin was therefore investigated. Guinea pig hearts underwent cold ischemic storage for 4 hr using Bretschneider's solution (histidine-tryptophan-ketoglutarate [HTK]) without and with augmentation with 1 g% human albumin. After reperfusion, intracoronary adhesion of polymorphonuclear granulocytes, edema formation, left and right heart performance of pressure-to-volume work, and glycocalyx shedding were assessed. Intracoronary retention of leukocytes was doubled in the traditional group (36.4+/-6.6%), whereas it remained at basal values after albumin preservation (23.5+/-2.4%; P<0.05). Addition of albumin to HTK significantly decreased edema formation (wet to dry weight ratio 6.9+/-0.1 vs. 7.2+/-0.2; P<0.05). Although left heart performance was comparable, right heart cardiac output was doubled in hearts having received HTK containing albumin versus HTK alone (94+/-14 vs. 50+/-11 mL/min/g; P<0.05). Glycocalyx shedding was significantly reduced when the hearts were stored under albumin protection. Augmenting HTK with human albumin improves endothelial integrity and heart performance after 4 hr cold ischemia, because of a marked protection of the endothelial glycocalyx. For the prevention of acute and chronic graft failure, the glycocalyx might represent a new target.

A STUDY OF LEFT ATRIAL APPENDAGE FLOW BY DOPPLER TRANSESOPHAGEAL ECHOCARDIOGRAPHY IN PATIENTS WITH ATRIAL SEPTAL DEFECT

Background: Transesophageal echocardiography TEE is performed in subjects with atrial septal defect (ASD) to define the characteristics of left atrial appendage (LAA) blood flow pattern. Normally, LAA flow velocity pattern is primarily determined by the left heart performance. We hypothesized that the impact of left – side heart dynamics on LAA flow velocity pattern is diminished in patients with ASD because of the presence of a left –to-right shunt into the low-resistance right side of the heart. Methods: Transesophageal echocardiography was performed in 29 adults with a large uncomplicated secundum ASD. Maximum defect diameter varied from 1.40 - to -3.9 cm, mean (2.37 ±0.79) cm. All patients were in normal sinus rhythm. Results: In 29 subjects the LAA flow velocity pattern lacked distinct early diastolic LAA outflow wave. Instead, we notice that the early diastolic LAA outflow and LAA contraction waves in late diastolic contraction tend to merge followed by a slightly higher emptying velocity (early systolic velocity).

Lungenerkrankungen und Herzfunktion

The most severe cardiac sequel to lung disease is the load on the right ventricle due to pulmonary hypertension with the development of a cor pulmonale. This is characterized by hypertrophy and/or dilatation of the right ventricle because of a primary impairment of lung function and/or lung structure. The most important pathomechanisms for the development of pulmonary hypertension are vessel obliteration, mechanical lesions, primary vascular or extra-vascular inflammation and hypoxic vasoconstriction. Chronic obstructive pulmonary disease (COPD) is one of the most important reasons for chronic cor pulmonale. A further very common reason is obstructive sleep apnea syndrome, especially if combined with a COPD. In this case, the prevalence of cor pulmonale can reach 80%. The development of a chronic cor pulmonale is the most striking negative prognostic factor for these patients. Only 30% of COPD patients with cor pulmonale survive longer than 5 years, and only early detection of the disturbances to respiration which might potentially lead to cor pulmonale and their subsequent therapy are able to improve the patient's prognosis. Furthermore, pulmonary diseases may also have an impact on the left heart side in terms of an impairment of left heart function or by inducing severe arrhythmias . Thus, lung diseases may have both a significant impact on right and left heart performance.

Pulmonary venous flow in large, uncomplicated atrial septal defect

Background: The pulmonary venous flow velocity pattern (PVFVP) in atrial septal defect (ASD) has not been previously studied in detail. Normally, PVFVP is primarily determined by the left heart performance. We hypothesized that the impact of left-sided heart dynamics on PVFVP is diminished in patients with ASD because of the presence of a left-to-right shunt into the low-resistance right side of the heart. Methods and Results: Transesophageal echocardiography was performed in 19 adults and 3 children with a large, uncomplicated secundum ASD (maximum diameter 0.6 to 3.0 cm). All patients were in normal sinus rhythm with an average heart rate of 78 bpm in adults and 116 bpm in children. In 21 subjects the antegrade PVFVP lacked distinct systolic (S) and diastolic (D) waves. Instead, we observed a single continuous antegrade wave extending from the beginning of systole to the onset of atrial contraction. Furthermore, the amplitude of the atrial reversal (AR) wave was smaller than in historical controls. In 3 patients in whom ASD was surgically repaired, we observed an immediate return of distinct S and D waves postoperatively. This confirmed that PVFVP abnormality was indeed the result of the ASD. Also a large increase in the AR wave amplitude (46 + 15 cm/s) was noted postoperatively. Conclusions: This previously unrecognized PVFVP comprising a single continuous antegrade wave and a diminished AR wave sheds new light on the hemodynamics of ASDs. Its presence may also alert the echocardiographer to the possibility of an ASD when the septal defect cannot be visualized directly. (J Am Soc Echocardiogr 2001;14:386-90.)

Heart transplantation--surgical results.

Heart transplantation has become a widely used therapeutic option for the treatment of end-stage heart failure. Since the first human orthotopic heart transplant in the late 1960s, the surgical technique has undergone several revisions. These revisions have addressed certain anatomic and geometric distortions that occurred with the original biatrial technique of Lower and Shumway. Early revisions have included the use of a bicaval technique for implanting the right atrium. Subsequently, the additional use of a direct pulmonary venous anastomosis has lead to the surgical concept of the total orthotopic heart transplant. These revisions of the original bi-atrial technique have led to a decrease in atrial size and distortion, conduction abnormalities and tricuspid and mitral valve regurgitation. This has also resulted in less atrial thromboembolic events, less need for permanent postoperative pacemaker placement, and in an overall increase in right and left heart performance in the early postoperative period. Overall, this has contributed to better clinical results with patients returning sooner to their normal exercise capacity. Ninety percent of heart transplant patients lead a relatively normal lifestyle having no limitations in their activity and 40 % return to work. We believe that the technique of total orthotopic heart transplantation has improved surgical results and clinical outcomes.

Computer-controlledin vitro model of the human left heart

The decision for surgical intervention in the treatment of stenosis and for regurgitation of the mitral valve demands an objective and quantitative evaluation of the severity of mitral valve disease. The availability of ultrasound techniques capable of analysing flow velocities across valves and to produce representative images of valve orifices has increased the interest in the hydraulics of cardiac valves. To isolate and study the determinants of transmitral flow, an in vitro model of the human left heart was built. From the model it is possible to differentiate the influence of the different determinants of left heart performance on transmitral flow: preload, compliance of the left atrium and ventricle, peripheral resistance (afterload) and heart rate. The mechanical part of the model consists of a reservoir connected to an elastic closed circuit (Latex pulmonary veins, left atrium, left ventricle and aortic arch) with replaceable mitral and aortic valves. The electronic part of the model drives and controls the hydraulic part, allowing the independent regulation and monitoring of left atrial and left ventricular pressures p, volumes V and 'pV-loops' throughout the cardiac cycle at different cardiac rhythms. Left atrial filling pressure and aortic resistance are variable in a controlled fashion. Echo-Doppler study of the mitral valve and the transmitral valve flow is possible both from an atrial and a ventricular window in the model. This technical note describes the model.

Predictability of left heart dysfunction from right heart performance--cardiac index-venous pressure plots and cardiac index-mean pulmonary artery wedge pressure plots at rest and their shift during dynamic exercise.

In an attempt to examine the extent to which the right heart performance can predict the left heart performance in heart diseases primarily affecting the left heart, we recorded cardiac index-venous pressure (CI-VP) plot and cardiac index-mean pulmonary artery wedge pressure (CI-PAW) plot at rest and investigated the shift of CI-VP plot and CI-PAW plot that occurred during mild dynamic exercise of the lower limbs. Six patients had normal heart function and 20 patients had heart diseases primarily affecting the left heart. The sensitivity, specificity, positive predictive value and negative predictive value in the estimation of the left heart function with delta CI/delta VP were 80%, 100%, 89% and 100%, respectively, when delta CI/delta PAW was regarded as the golden standard for the estimation of the left heart function. The sensitivity, specificity, positive predictive value and negative predictive value in estimating the left heart function with delta CI/delta RA were 86%, 93%, 92% and 86%, respectively. When the left heart function was estimated by delta VP alone without measuring delta CI, the sensitivity, specificity positive predictive value and negative predictive value were 40%, 100%, 73% and 100%, respectively. In short, it was possible to predict the left heart dysfunction with delta CI/delta VP or delta CI/delta RA, in the presence of the right heart dysfunction. It was also possible to predict a steep heart slope from normal delta CI/delta VP with error of 2/18 (11%), when steep left heart slope was predicted, based on the presence of steep right heart slope. In comparison, delta VP alone was a less sensitive index of the performance of the left heart.

Experimental approaches to myocardial function studies: C 15O 2 and 81mKr

The role of short-lived gaseous radiotracers in myocardial function studies is reviewed. The evaluation of shunts and ejection fractions characterizing individual chambers is best performed with tracers restricted to those chambers. Classic examples include the C15 O2 inhalation radiocardiogram for probing the left-heart performance, with the right heart illuminated by intravenous 133Xe in saline. A more elegant utilization of rapid physical decay to unravel flow patterns is seen in the use of 81m Kr. Krypton-81m is swept from its parent 81Rb, either confined to an extracorporeal generator or an in vivo rubidium distribution. The steady-state images that result contain a wealth of dynamic information distilled into its most lucid format.