Reduced left ventricular function and sustained hypertension in women seven years after severe preeclampsia

Objective. To study left ventricular (LV) function and blood pressure (BP) at a long-term follow-up in women after severe pre-eclampsia. Design. In this single-centre, cross-sectional study, 96 patients were eligible for inclusion. LV function was examined by transthoracic echocardiography including tissue Doppler echocardiography and speckle tracking. BP was measured at rest using repeated non-invasive techniques. Results. We compared 36 patients with early-onset and 33 patients with late-onset pre-eclampsia with 28 healthy controls. Mean age (40 ± 3 years) and median time since delivery (7 ± 2 years) were similar across the study groups. The patients had 18% higher systolic BP (139 ± 15 mmHg) and 24% higher diastolic BP (87 ± 19 mmHg) than controls (p < .01). Hypertension was present in 23 patients (33%), where the estimated LV mass was 16% higher (p = .05) than in controls. The LV ejection fraction was 19% lower in the early-onset group (51 ± 4%; p = .01) and 14% lower in the late-onset group (54 ± 6; p = .04) compared with controls. LV global longitudinal strain was 18% lower in the patient group (-17.7 ± 2.1%) compared with controls (p = .01). Indicative of a more restrictive filling pattern, the diastolic indices showed a lower e' mean (p < .01) and subsequently higher E/e' ratio (p < .01). There were no significant differences in BP, systolic or diastolic function indices between the patient groups. Conclusion. We found sustained hypertension, higher LV mass and reduced LV systolic and diastolic function 7 y after severe pre-eclampsia. Our findings emphasize the importance of early risk stratification and clinical counselling, and follow-up for such cases.

Left ventricular mechanical dispersion by speckle tracking echocardiography is a predictor of atrioventricular block after transcatheter aortic valve implantation

Background

Transcatheter Aortic Valve Implantation (TAVI) is an effective therapy for patients with severe aortic stenosis (AS). Complete atrioventricular block (AVB) that requires permanent pacemaker implantation is a common complication of TAVI. Direct mechanical effect of the prosthetic valve, QRS duration and underlying myocardial fibrosis are proposed mechanisms of AVB after TAVI. Left ventricular mechanical dispersion (LVMD) by Speckle Tracking Echocardiography (STE) is an index of contraction heterogeneity and a marker of myocardial fibrosis.

Purpose

We aimed to evaluate the association between LVMD, QRS duration and AVB to assess markers used to predict AVB after TAVI.

Methods

A total of 163 consecutive TAVI patients were enrolled in the study. Echocardiograms andelectrocardiograms were recorded the day before TAVI procedure to assess global longitudinal strain (GLS), LVMD and QRS duration. AVB and pacemaker (PM) implantation information was obtained by telephone interviews three months after TAVI.

Results

Ten patients were excluded due to poor image quality. Of the 153 patients analyzed, 45% were female. Mean age was 80±7 years. In our patient cohort 15.7% of the patients received PM within three months after TAVI. GLS and QRS duration was not different between AVB group and No-AVB group (−15.8±4.5% vs −16.9±4.4%, p=0.26 and 107±31ms vs 102±18ms, p=0.24 respectively). LVMD was prolonged in patients with subsequent AVB compared to patients with No-AVB (60±19ms vs 48±13ms, p&lt;0.001) (Figure 1). LVMD predicted AVB after TAVI with area under the curve 0.71. LVMD predicted AVB independently of QRS duration (odds ratio 1.68; 95% confidence interval 1.23–2.3; p=0.001 by 10ms increments) (Table 1).

Conclusion

LVMD predicted AVB after TAVI independent of QRS duration. LVMD may be of added value as a myocardial functional echocardiographic predictor of this important and frequent complication of TAVI.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): EACVI Research Grant 2020

Pregnancy history and long-term progression of cardiomyopathy in LMNA genotype-positive women

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Precision Health Center for optimized cardiac care (ProCArdio), Oslo, Norway Fripro gene positive, Norwegian Research Council, Oslo, Norway

Background

Competitive and non-competitive exercises have been reported to be deleterious on prognosis of LMNA genotype-positive patients. Comparable to exercise, pregnancy is a prolonged hemodynamic stress situation.

Aims

We aimed to assess the association between pregnancy history and long-term progression of cardiomyopathy in women with pathogenic or likely pathogenic variants of LMNA (LMNA+).

Methods

We retrospectively included consecutive LMNA+ females and recorded pregnancy data. We analyzed repeated echocardiographic examinations, including data on left ventricular (LV) end-diastolic diameter (EDD), LV ejection fraction (EF) and LV global longitudinal strain (GLS). We recorded the occurrence of atrial fibrillation (AF), atrioventricular block, sustained ventricular arrhythmias (VA), and implantation of cardiac electronic devices (ICD/CRT-D). We analysed retrospectively complications during pregnancy and peripartum period.

Results

We included 89 LMNA+ women (28% probands, age 41 ± 16 years), of which 60 had history of pregnancy. Follow-up duration was 5 [IQR: 3-9] years. We analysed 452 repeated echocardiographic examinations. Women with previous pregnancy and nulliparous had a similar annual deterioration of LV EF (-0.5/year vs -0.3/year, p = 0.37, figure left panel), LV GLS (0.1/year vs 0.0/year, p = 0.35, figure right panel) and LV EDD (0.1/year vs 0.2/year, p = 0.09). Number of pregnancies was not associated with increased long-term risk of AF, atrioventricular block, sustained VA or ICD/CRT-D implantation. Pregnancy history was not associated with worse survival free from death, left ventricular assist device or need for cardiac transplantation. Arrhythmias occurred in 9% of pregnancies. No increase of maternal and fetal complications was observed.

Conclusions

In our cohort of LMNA+ women, pregnancy was not associated with long-term adverse progression of cardiac dysfunction, worsening in arrhythmic progression or reduced event-free survival. Likewise, LMNA+ women generally tolerated pregnancy well, with a small proportion of patients experiencing arrhythmias. Abstract Figure.

Is left ventricular function reduced after ultra-endurance exercise?

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Norwegian Health Association

Introduction

Ultra-endurance exercise can be harmful according to previous studies, indicated by reduction in functional parameters and increase in cardiac biomarkers. Changes in load and heart rate with exercise influence left ventricle systolic function, making assessment of standard echocardiographic examination difficult.

Purpose

We investigated the effect of ultra-endurance exercise on myocardial function acutely and at restitution.

Methods

We investigated 10 participants aged 46 ±7 years, before (baseline), within 142 ± 78 minutes after finish (post run) and 5-10 days after (restitution) an ultra-endurance race (3.8 km swimming, 180 km bicycling and 42 km running with a total elevation of 5200 m). Echocardiography was performed at the three time points, including cardiac morphology and -function. Ejection fraction (EF) and stroke volume (SV) were measured by Simpson biplane. Cardiac output was calculated from SV and heart rate (HR). Cardiac power was calculated as the product of CO, mean arterial blood pressure and the conversion factor to Watt (W) 0.00222. Global longitudinal strain (GLS) was calculated using speckle-tracking echocardiography, and myocardial work was calculated by non-invasive pressure-strain analysis.

Results

Acutely after exercise, myocardial function by GLS (p = 0.002), myocardial work (p &lt; 0.001), mitral annular plane systolic excursion (MAPSE, p = 0.003) and EF (p = 0.004) were substantially reduced compared to baseline, whereas cardiac power and cardiac output (CO) were maintained (see table and figure). Heart rate was moderately increased (p &lt; 0.001). End-diastolic volume (EDV) as an index of preload was numerically, but not significantly reduced. End systolic volume (ESV) was numerically increased (p = NS) even though systolic blood pressure (sBP) was reduced (p = 0.01) post race. After restitution all parameters returned to baseline levels.

Conclusions

The temporary reduced strain and EF may be a physiologic response due to the higher heart rate. However, despite reduced systolic pressure the heart did not contract to a lower end systolic volume. This suggests loss of contractile function compensated by increase in heart rate. The findings should be explored in further studies. Abstract Figure  Abstract Table

Pre-intervention left ventricular mechanical dispersion is increased in patients in need for pacemaker after TAVI

Funding Acknowledgements

Type of funding sources: None.

Background and Purpose

Transcatheter Aortic Valve Implantation (TAVI) is an effective therapy for patients with severe aortic stenosis. Complete atrioventricular block (AVB) that requires permanent pacemaker treatment is a common complication of TAVI and it is reported in up to one fifth of patients. Prediction of this complication could be important. Global longitudinal strain (GLS) and left ventricular mechanical dispersion (LVMD) by speckle tracking echocardiography (STE) are novel techniques that detect subtle changes in myocardial function and are related to myocardial fibrosis. Thus, we aimed to investigate the association between LVMD and AVB development after TAVI.

Methods

We retrospectively screened 168 consecutive patients after TAVI. Patients with abnormal ECG and changed conduction pre- and post-TAVI were excluded. Data from the remaining 61 patients were compared to the group of 16 patients in need for a permanent pacemaker. Baseline echocardiograms recorded before TAVI were used to assess GLS and LVMD by STE (Figure).

Results

Of the 77 patients analysed, 60% were female (82 ± 7 years old). The mean GLS values were -16.8 ± 4.2% and -16.9 ± 3.7% in AVB and no AVB groups, respectively (p = 0.9). The mean LVMD was 60 ± 19 ms in AVB group and 50 ± 16 ms in no-AVB group (p = 0.04). (Table)

Conclusion

LVMD was increased in patients who developed TAVI-induced complete AVB, while GLS could not differentiate between post-procedural normal and abnormal electrical conduction. This finding may be important to identify myocardial properties associated with complete AVB after TAVI. Abstract Table  Abstract Figure

Myocardial work still reflect function while strain simply measure deformation when afterload increases

Introduction

Global longitudinal strain is recommended by the European Society of Cardiology to detect subclinical left ventricular (LV) dysfunction, but is markedly load-dependent. Myocardial work was recently introduced as a clinical tool to study LV function by pressure-strain analysis. Since myocardial work incorporates afterload, it is assumed to be less afterload-dependent than strain, but the relationship with afterload is incompletely understood.

Hypothesis

Myocardial work is a better tool than strain, to measure myocardial function during elevated afterload.

Methods

In eleven anesthetized dogs, LV volume and longitudinal strain were measured by sonomicrometry, and pressure by micromanometry. Myocardial work was calculated by pressure-strain analysis. Additionally, stroke work was calculated as the area of the pressure-volume loop. Afterload was instantly increased by aortic constriction using a pneumatic cuff around the ascending aorta. Measurements were performed at baseline, during moderate- and marked afterload elevations.

Results

Table 1 summarizes the results. LV pressure (LVP) successively increased with moderate and marked afterload elevation, while longitudinal strain was successively reduced. Myocardial work and stroke work, on the other hand, increased with moderate afterload elevation, but was then reduced at marked afterload increase (Figure 1 and Table 1). Stroke volume and ejection fraction corresponded to strain and were reduced with afterload elevation.

Conclusions

Longitudinal strain and myocardial work have qualitatively different responses to increased afterload. While moderate changes in afterload cause reductions in strain that can be falsely interpreted as reductions in contractility, myocardial work increases as it incorporates the increased workload at moderately elevated afterload.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association

Deep learning for automated left ventricular outflow tract diameter measurements in 2D echocardiography

Background

Left ventricular outflow tract diameter (LVOTd) is routinely measured to calculate stroke volume and estimate aortic valve area by the continuity equation. Despite LVOTd being regularly measured clinically, significant inter- and intraobserver variability is evident. This variability is highly impactful on both aortic stenosis evaluation and cardiac output calculation due to the squaring of the LVOT radius.

Purpose

We aimed to investigate if LVOTd measurements from clinical echocardiographic examinations could be used in a deep learning (DL) model to automatically perform LVOTd measurements with equivalent accuracy and improved consistency compared to current practice.

Methods

Data was collected from clinical echocardiographic examinations performed on 656 consecutive patients admitted to the cardiac catheterization laboratory at a university hospital in January – December 2018. Parasternal views with cardiologist annotated LVOTd coordinates were assessed for 1314 echocardiographic still images. The quality of the still image and annotated LVOT ground truth were individually graded as high, medium and low by experienced cardiologists to establish a rigorous training basis. Spatial geometry data was preserved for each still image in order to distinguish between different degrees of image zoom. Data was randomly split into training, validation and testing sets (68%, 17%, 15%). A fully convolutional network based on the Resnet50 architecture was used with a custom loss function with heatmap regression. Image augmentations were added to extend the dataset.

Results

When including echocardiographic images of any quality (n=1314) in the model training and inference, the median absolute difference between cardiologist LVOTd and DL LVOTd was 0.97 mm (95% Confidence interval (CI) 0.79–1.14). Using only high and medium quality still images and ground truth (n=869) in the training and inference, median absolute difference decreased to 0.81 mm (95% CI 0.60–0.96). Adding image augmentations to this dataset further improved the model, resulting in a median LVOTd absolute difference of 0.66 mm (95% CI 0.51–0.78). The LVOTd error in inference increased with decreasing image quality, as shown in Figure 1, with two predictions (0.9%) failing completely.

Conclusion

Deep learning models are capable of measuring LVOTd with comparable accuracy to cardiologists when trained on clinical data. Data quality affects both training and inference. Even with a slightly lower accuracy when used on lower quality echocardiographic images, DL-assisted LVOT measurement has a clear potential to increase repeatability and consistency of LVOTd measurements.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Research Council of Norway (Norges forskningsråd) Figure 1

Cardiac function is normal in most patients recovered from COVID-19

Background

There are conflicting results regarding impaired cardiac function in patients that have recovered from COVID-19. Cardiovascular magnetic resonance (CMR) studies have revealed a very high frequency of cardiac involvement (78%) and ongoing myocardial inflammation (60%) in patients recently recovered from COVID-19. Findings are advocating further investigation of the long-term myocardial consequences of COVID-19 disease.

Purpose

We aimed to investigate left ventricular (LV) and right ventricular (RV) function by a comprehensive echocardiographic study in patients recovered from COVID-19 infection 3 months after admission to hospital.

Methods

All patients (n=92) had been hospitalized for COVID-19 and were examined with echocardiography three months after hospitalization. They were 59±13 years, and 43% were women. LV function was assessed by ejection fraction (EF) and global longitudinal strain (GLS) and RV function was measured by fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE) and RV GLS free wall. Tricuspid regurgitation pressure gradient was measured to estimate pulmonary artery pressure.

Results

LV EF was 63±6% and LV GLS was −18.6±2.2%. All patients had normal EF &gt;53%, but 10 showed signs of subtle impaired LV function by LV GLS (≥ −16%). Only two of these did not have hypertension, LV hypertrophy, diabetes or other preexisting diagnosis of heart disease explaining subtle LV dysfunction. All had normal RV FAC (48±7%) and TAPSE (2.3±0.3 cm). We found modestly impaired RV longitudinal function (RV GLS free wall &gt;−25%) in 30% patients, but none had RV GLS worse than −20%. One-third of all patients with reduced RV GLS had signs of elevated pulmonary arterial pressures, which might impact the assessment of RV function.

Conclusions

Traditional echocardiographic parameters showed normal function in all hospitalized COVID-19 patients three months after hospital admittance. Approximately one-third had subtle ventricular dysfunction detected by sensitive echocardiographic methods, but these findings could mostly be explained by systemic or pulmonary hypertension. We cannot, however, exclude that a slight reduction in cardiac function in a minority of our patients was caused by the COVID-19 infection.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): National Clinical Therapy Research in the Specialist Health Services, Norway

Myocardial work comes to rescue when afterload-dependency of strain cause false positives

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association

Introduction

Global longitudinal strain (GLS) can detect subclinical left ventricular (LV) dysfunction. GLS measurement is therefore recommended when chemotherapy-induced cardiotoxicity can be suspected. A relative, percentage reduction in GLS ≥8% may indicate subclinical LV dysfunction induced by chemotherapy. Due to afterload-dependency, moderate increase in blood pressure has the potential to cause reductions in GLS beyond this threshold. However, myocardial work incorporates afterload, and may be used to omit false positive outcomes.

Purpose

To investigate if moderate increases in afterload cause clinically relevant changes in strain, and if myocardial work is more robust to such changes.

Methods

Twenty cancer patients (41 ± 14 years) undergoing chemotherapy and twenty healthy controls (49 ± 11 years, NS) were included. All participants were free from concomitant heart disease. GLS was measured by speckle-tracking echocardiography. Global myocardial work was calculated by pressure-strain analysis using a previously validated method to estimate LV pressure (LVP) non-invasively. Recordings were performed before and after 2 minute stress by handgrip.

Results

At baseline, patients had lower GLS (20.1 ± 1.1 vs 22.1 ± 2.5%, p &lt; 0.01) and global myocardial work (1810 ± 203 vs 2051 ± 287 mmHg·%, p &lt; 0.01) than controls. Stress test moderately increased systolic blood pressure, similar in both groups (116 ± 10 to 146 ± 17 mmHg in patients, and 118 ± 12 to 147 ± 21 mmHg in controls). This afterload-enhancement was associated with a decrease in GLS from 20.1 ± 1.1 to 18.4 ± 1.3% in patients, and from 22.1 ± 2.5 to 20.3 ± 2.5% in controls (both p &lt; 0.01). Every second participant, eleven patients and nine controls, experienced a relative reduction in GLS &gt;8%. In contrast, global myocardial work increased during the stress test from 1810 ± 203 to 2002 ± 281 mmHg·% in patients, and from 2051 ± 287 to 2292 ± 398 mmHg·% in controls (both p &lt; 0.01). Figure 1 shows changes in GLS and myocardial work at moderate increase in afterload.

Conclusions

Moderate increase in afterload caused reductions in GLS sufficient to promote over-diagnosis of chemotherapy-induced cardiotoxicity. Global myocardial work has the potential to distinguish true subclinical LV dysfunction from afterload-induced decline in GLS.

Abstract Figure.

Regional myocardial work as determinant of heart failure in left bundle branch block

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association

Background

Left bundle branch block (LBBB) worsen prognosis in heart failure patients. LBBB may also cause heart failure in otherwise healthy individuals. The mechanical changes induced by LBBB are potential determinants of heart failure in these patients, but their relation to left ventricular (LV) systolic function is incompletely understood.

Purpose

This study investigates the contribution of regional contractile function to heart failure in patients with LBBB.

Methods

In 76 patients with LBBB and 11 healthy controls, myocardial strain was measured by speckle-tracking echocardiography and myocardial work by pressure-strain analysis. Patients with ischemic heart disease or myocardial scarring were excluded. LBBB patients were stratified by LV ejection fraction (EF) &gt;50% (EFpreserved), 36-50% (EFmid), and ≤35% (EFlow). 62 LBBB patients subsequently underwent cardiac resynchronization therapy (CRT) implantation and was re-examined at 6 months.

Results

Septal work was significantly and successively reduced from controls, EFpreserved, EFmid, to EFlow (1977 ± 506, 1025 ± 342, 601 ± 494 and -41 ± 303 mmHg·%, respectively, all p &lt; 0.01) (Figure 1). There was a strong correlation (R = 0.84, p &lt; 0.01) between septal work and LVEF. In contrast, work in the LV lateral wall was preserved in both EFpreserved (2367 ± 459 mmHg·%) and EFmid (2252 ± 449 mmHg·%) vs controls (2062 ± 459 mmHg·%, all NS). In the EFlow group, however, LV lateral wall work was reduced (1473 ± 568 mmHg·%, p &lt; 0.01 vs controls). Thus, lateral wall function was not correlated with LVEF in patients with LVEF &gt;35% (NS). At six month CRT septal work was markedly increased (165 ± 485 vs 1288 ± 523 mmHg·%, p &lt; 0.01) and LV lateral wall work reduced (1730 ± 620 vs 1264 ± 490 mmHg·%, p &lt; 0.01). LVEF increased from 32 ± 8 to 47 ± 10 % (p &lt; 0.01).

Conclusions

Heart failure in LBBB patients is determined by degree of septal dysfunction. LV lateral wall function, on the other hand, is preserved in the early phase of heart failure and was only reduced in patients with severe heart failure. Further clinical studies should investigate if measuring LV lateral wall function can increase precision in patient selection for CRT.

Abstract Figure.

Elevated septal wall stress - a driver of left ventricular dysfunction in left bundle branch block?

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association

Background

Septal dysfunction is a main feature of left bundle branch block (LBBB), and increasing wall stress is a proposed mechanism of heart failure development in LBBB patients. To try to reveal the pathophysiologic pathway from dyssynchrony to heart failure, we investigated the relationship between septal and left ventricular (LV) lateral wall stress in patients with LBBB.

Hypothesis

Increased septal wall stress causes septal dysfunction in LBBB.

Methods

We included 24 LBBB-patients (65 ± 11 years, 11 males) with LV ejection fraction (EF) ranging from 18 to 67%, and 8 healthy controls (58 ± 10 years, 4 males). Wall stress was calculated at peak LV pressure (LVP) according to the law of La Place ([LVP x radius]/[wall thickness]). Wall thickness was measured using M-mode, and regional curvature was measured in mid-ventricular shortaxis from 2D echocardiographic images. We used a previously validated non-invasive method to estimate LVP from brachial blood pressure and adjusted for valvular events. Myocardial scar was ruled out by late gadolinium enhancement cardiac magnetic resonance imaging.

Results

Wall stress was significantly higher in septum than LV lateral wall at peak LVP (48 ± 12 vs 37 ± 11 kPa, p &lt; 0.01) in LBBB patients, while no difference was seen in the controls (Figure A). In patients, septal wall thickening showed a strong correlation with LVEF (r = 0.77, p &lt; 0.01) (Figure B). Similar correlation was not significant for the LV lateral wall (r = 0.13, NS). Attenuation of septal wall thickening in LBBB-patients correlated well with increasing septal wall stress (r=-0.60, p &lt; 0.01). Wall thickening and stress did not correlate in the LV lateral wall (r=-0.14, NS).

Conclusion

Increased septal wall stress is associated with reduced systolic thickening in patients with LBBB. Septal wall thickening, in contrast to LV lateral wall thickening, was correlated to global LV function. These findings suggest that septal remodeling which could have normalized septal wall stress, was not achieved and heart failure may develop.

Abstract Figure.

Impact of pregnancy and risk factors for ventricular arrhythmias in women operated for tetralogy of Fallot

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): South-Eastern Norway Regional Health Authority

Background

Patients with tetralogy of Fallot (TOF) have a high survival rate 30 years after surgical repair, and generally enjoy a satisfactory quality of life. Many female patients experience pregnancy during adulthood, however the effects of pregnancy on the long-term cardiovascular outcome in this group of patients are not well known.

Purpose

We aimed to investigate the association of pregnancy and cardiac function with occurrence of ventricular arrhythmia (VA) in women operated for TOF.

Methods

We included 80 patients recruited from the national database for patients diagnosed for TOF. All were examined with echocardiography, including strain echocardiography. We assessed mechanical dispersion of right ventricle (RV) as measure of heterogeneous contraction. Holter monitoring or implanted devices detected ventricular arrhythmias (VA), defined as non-sustained or sustained ventricular tachycardia or aborted cardiac arrest. Blood tests included N-terminal pro-brain natriuretic peptide (NT-proBNP).

Results

In all, 55 (69%) women had experienced pregnancy (age 40 ± 9 years, parity median 1, range 1-4), while 25 (31%) women were nulliparous. The mean age was lower in nulliparous compared to those with children (30 ± 9 vs 40 ± 9, p &lt; 0.01).

VA was more prevalent in women who had experienced pregnancy (n = 16, 94%) compared to nulliparous (n = 1, 6%) (p = 0.02), and importantly also when adjusted for age [adjusted OR 9.8 (95% CI 1.2-79.1), p = 0.02].

RV mechanical dispersion was more pronounced in patients with VA [39.2 ± 14 ms vs. 49.6 ± 8 ms, p = 0.009, adjusted OR 2.1 (95% CI 1.3 - 7.5), p = 0.01 adjusted for age]. Higher NT-proBNP was also a marker of VA [211 ng/L (127-836) vs. 139 ng/L (30-465), p = 0.007, adjusted OR 1.4 (95% CI 1.1 - 1.8) p = 0.017 adjusted for age]. NT-proBNP &gt;182 ng/L (normal values &lt; 170 ng/L) optimally detected women with VA (p = 0.019), also independent of age [OR 7.2 (95% CI 1.7-30.1), p = 0.007].

Conclusion

History of pregnancy was associated with higher prevalence of VA among women with surgically corrected TOF. Right ventricular mechanical dispersion and NT-proBNP were age independent markers of VA. These findings may have importance for risk stratification and preconception counselling of these patients.

Assessment of left ventricular filling pressure: left atrial reservoir strain is an excellent replacement for missing tricuspid regurgitation velocity

Background

When evaluating left ventricular filling pressure (LVFP) according to current guidelines, tricuspid regurgitation (TR) velocity is often not available.

Purpose

In the present study we investigate if left atrial (LA) reservoir strain may be used instead of TR velocity for evaluation of LVFP.

Methods

We performed a prospective, multicenter, multinational and multivendor study in an all comer population of 322 patients with suspected heart failure or other cardiovascular disease where LVFP was measured by right- or left heart catheterization, as pulmonary capillary wedge pressure or pre-A LV diastolic pressure, respectively. Echocardiography was performed within 1 day of catheterization.

101 patients classified as special populations in the 2016 ASE/EACVI recommendations (i.e. non-cardiac pulmonary hypertension, atrial fibrillation, hypertrophic and restrictive cardiomyopathies) were excluded. Of the remaining 221 patients, 118 patients had EF ≥50% and 103 patients had EF &lt;50%. Regression analysis was performed for LA reservoir strain and TR velocity against LVFP. LA reservoir strain at a cut-off value of &lt;18% was applied instead of TR velocity in the 2016 ASE/EACVI algorithm and compared with the current algorithm.

Results

LA reservoir strain correlated better with LVFP than TR velocity, r=0.62 vs 0.40 (p&lt;0.01) (Figure 1). When replacing TR velocity with LA reservoir strain, the feasibility of the ASE/EACVI 2016 algorithm increased from 91.8% to 98.1%. The accuracy of the algorithm was not significantly altered (80% vs 79%).

An accuracy of 80% for the algorithm is lower than what has been reported in earlier publications, this may be due to inclusion of patients without suspected heart failure and no assessment of clinical data, which in turn may have influenced the accuracy of the algorithm.

Conclusion

LA reservoir strain has better correlation to LVFP than TR velocity, and can be used in the ASE/EACVI 2016 algorithm for estimation of LVFP as a replacement when TR velocity is missing.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): South-Eastern Norway Regional Health Authority

Which single echo parameter is the best marker of left ventricular filling pressure?

Background

Estimation of left ventricular filling pressure (LVFP) is highly relevant in clinical practice. Invasive pressure remains the gold standard, but a number of echocardiographic parameters that correlate with LVFP are used as non-invasive markers of pressure.

Purpose

We investigated how different echocardiographic parameters correlated with invasively measured LVFP, and how accurately those parameters could differentiate between normal or elevated LVFP.

Method

We performed a prospective, multicenter, multinational and multivendor study in an all comer population of 322 patients with suspected heart failure or other cardiovascular disease. 194 patients had EF ≥50% and 129 had EF &lt;50%. LVFP was measured by right- or left heart catheterization, as pulmonary capillary wedge pressure or pre-A LV diastolic pressure, respectively.

When excluding all special patient populations defined in the 2016 recommendations for echocardiographic evaluation of LV diastolic function, 213 patients remained. Of these 135 had EF ≥50% and 74 had EF &lt;50%.

Echocardiography was performed within 1 day of catheterization. Previously recommended cut-off values for established parameters were used to determine the accuracy of classifying LVFP as normal or elevated. For left atrial (LA) reservoir strain, based on ROC analysis, a cut-off value of &lt;18% was used as marker of elevated LVFP.

Results

LA reservoir strain and the ratio of peak mitral early flow velocity (E) and LA reservoir strain (E/LA strain) showed the best correlations to LVFP (Table 1, Figure 1). They also had the highest accuracy, 75% for both, in classifying LVFP as normal or elevated in the whole patient population. E/LA reservoir strain provided no additional diagnostic value to using LA reservoir strain alone.

In HFpEF patients accuracy was essentially similar for LA strain, E/LA strain and E/e', whereas in HFrEF patients the two former tended to be better than E/e'.

Conclusion

Parameters containing LA reservoir strain showed the best correlation to LVFP. This indicates that LA reservoir strain may have a role in evaluation of LVFP.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): South-Eastern Norway Regional Health Authority

158 Myocardial work exposes afterload-dependent changes in strain

Funding Acknowledgements

Norwegian Health Association

Background

Global longitudinal strain (GLS) is used for detection of subclinical left ventricular (LV) dysfunction, for example when screening for chemotherapy-induced cardiotoxicity. A relative percentage reduction in GLS ≥8% is considered abnormal. However, as GLS is load-dependent, modest increases in afterload can potentially prove sufficient to cause clinical implication. In contrast, global myocardial work (GMW) which incorporates afterload, may be more accurate in detecting LV-dysfunction.

Purpose

We investigated the effect of increased afterload on GLS, and if GMW may be a more accurate parameter of myocardial function during increased afterload.

Methods

In 20 healthy individuals (age 49 ± 11 years (mean ± SD), 10 men), blood pressure was increased by a 3 minute arithmetic mental stress test. GLS was measured by speckle tracking echocardiography and LV ejection fraction (EF) by biplane Simpson. GMW was calculated from LV pressure-strain analysis using a non-invasive estimate for LV pressure (LVP).

Results

During the afterload-elevation, systolic blood pressure increased by 25 ± 16 mmHg (p &lt; 0.01), and heart rate by 16 ± 13 bpm (p &lt; 0.01). This was followed by a decrease in EF from 62 ± 5 to 59 ± 5% (p &lt; 0.01) and GLS from 21.9 ± 2.2 to 20.8 ± 2.0% (p &lt; 0.01). In contrast, GMW increased from 2052 ± 278 to 2382 ± 388 mmHg·% (p &lt; 0.01). In 5 of 20 (25%) individuals, the relative percentage reduction of GLS was &gt;8%, despite an increase in GMW. The figure shows an individual example during rest and afterload-elevation, where an increase in systolic blood pressure of 16 mmHg was associated with a 9% relative percentage reduction in GLS, but a small increase in GMW as illustrated by the loop areas.

Conclusions

This study demonstrated that a modest increase in afterload can result in significant reduction in GLS, that may lead to overdiagnosis of LV-dysfunction. GMW did not decrease, suggesting it has a better specificity in patients at risk for subclinical LV dysfunction. Future studies should investigate if GMW is more accurate than strain in detecting LV-dysfunction.

Abstract 158 Figure.

1231 Left atrial septal and lateral wall strains contain different pressure information: Utility in pulmonary hypertension

Funding Acknowledgements

South-Eastern Norway Regional Health Authority

Background

Reduced left atrial (LA) reservoir strain is a marker of elevated LA pressure. Thus it could be a potential non-invasive marker to differentiate pre- and post-capillary pulmonary hypertension (PH) as the latter is defined by elevated pulmonary capillary wedge pressure (PCWP) &gt; 15 mmHg. However, in pre-capillary PH patients with elevated right atrial pressure (RAP), the atrial septal geometry may be abnormal. This could lead to lower regional LA septal strain, making LA lateral wall strain more accurately reflect PCWP.

Purpose

We investigated if LA lateral wall strain can differentiate between pre- and post-capillary PH, and how LA lateral wall strain and LA septal strain are both affected by elevated RAP in pre-capillary PH. Furthermore we investigated if LA septal strain can be used in pre-capillary PH patients to identify those with elevated RAP.

Methods

We analysed 63 patients with PH, 28 pre-capillary and 35 post-capillary, who underwent right heart catheterisation. Echocardiography was performed simultaneously with or within 24 hours of the invasive pressure measurements. Regional LA septal strain and lateral wall strain were measured from the apical four chamber view.

Results

Pulmonary artery pressure was 39.5 ± 11.1 mmHg (mean ± SD) in the pre-capillary PH patients and 37.0 ± 10.1 mmHg in the post-capillary PH patients (p = ns). Mean PCWP was 9.9 ± 2.5 mmHg and 24.5 ± 6.0 mmHg (p &lt; 0.001), respectively.

LA lateral wall strain was significantly lower in patients with post-capillary PH compared to pre-capillary PH (11.9 ± 7.7% vs 26.6 ± 9.9%, p &lt; 0.001) (Fig. a,b). At a cut-off value of 18.0%, LA lateral wall strain could predict elevated PCWP &gt; 15 mmHg with AUC = 0.88, sensitivity = 85.7% and specificity = 76.3%.

In the 28 patients with pre-capillary PH, we classified mean RAP ≥ 10 mmHg as elevated and &lt; 10 mmHg as normal. Seven of these patients had elevated RAP and showed significantly reduced LA septal strain compared to the 21 patients with normal RAP (13.0 ± 6.2% vs 22.1 ± 7.6%, p &lt; 0.01). LA lateral wall strain showed no difference in these groups of pre-capillary PH patients (25.8 ± 10.1% vs 28.9 ± 9.4%) (Fig. c).

Conclusions

LA lateral wall strain can be used for differentiating between pre- and post-capillary PH. In addition, LA septal strain may be used in pre-capillary PH patients to identify those with elevated RAP.

Abstract 1231 Figure

P4368Estimation of pulmonary artery pressure from right atrial strain and tricuspid regurgitation velocity

Background

Systolic pulmonary artery pressure (SPAP) can be estimated non-invasively as the sum of indices for right atrial (RA) pressure and tricuspid regurgitation (TR) pressure gradient. Although echocardiographic evaluation of inferior vena cava diameter and collapsibility is currently being used to estimate RA pressure (IVC method), RA strain may be an alternative since atrial strain is related to atrial pressure.

Objective

We tested if RA strain by speckle tracking echocardiography can be used as a surrogate of mean RA pressure (RA strain method), and by adding the TR pressure gradient, be used to estimate SPAP.

Methods

We retrospectively analyzed 91 patients (mean age, 58 years) referred to right heart catheterization due to unexplained dyspnea or suspected pulmonary hypertension. Echocardiography was performed within 24 hours of the invasive procedure. RA reservoir strain was calculated from apical four-chamber view. SPAP was calculated as the sum of peak TR pressure gradient and estimated RA pressure by the IVC or RA strain methods.

Results

Right heart catheterization showed SPAP and mean RA pressures of 51±20 mmHg and 9±6 mmHg, respectively. RA reservoir strain was inversely correlated with mean RA pressure (r=−0.61, p<0.01). Thus, we set mean RA pressure as 5, 10 and 15 mmHg depending on high (≥25%), middle (10–25%) and low (≤10%) values of RA reservoir strain. As shown in the figure, both the RA strain and IVC methods when combined with peak TR velocity, provided good estimates of invasively measured SPAP.

Conclusions

RA strain provides a semiquantitative measure of RA pressure, which can be used in combination with peak TR velocity to estimate SPAP. This approach can be used as an alternative when the IVC method is not available in cases with poor subcostal window.

1175Structural progression increases the risk of ventricular arrhythmias in patients with arrhythmogenic cardiomyopathy

Background

Arrhythmogenic cardiomyopathy (AC) is an inheritable cardiomyopathy with incomplete penetrance, variable phenotype severity and poorly described disease progression. It is characterized by high risk of life-threatening ventricular arrhythmias and sudden cardiac death in young individuals. Risk stratification and selection of patients presenting without history of life-threatening arrhythmic events for cardioverter-defibrillator implantation in primary prevention remains challenging.

Purpose

We aimed to assess the impact of disease progression on arrhythmic outcomes in AC patients.

Methods

We included consecutive AC probands and mutation-positive family members with at least one complete follow-up evaluation. Echocardiographic and electrical parameters were defined according to the 2010 Revised Task Force criteria at inclusion and at last follow-up. Structural progression was defined as development of new echocardiographic diagnostic criteria. Electrical progression was defined as the development of new diagnostic depolarization, repolarization and/or premature ventricular complex count criteria during follow-up. Non-sustained ventricular tachycardia or ventricular tachycardia occurring during follow-up defined incident ventricular arrhythmic events.

Results

We included a total of 144 patients (48% female, 47% probands, 40±16 years old). At inclusion, 54 patients (37%) had a history of arrhythmic events, 30 patients (21%) had overt structural disease and 114 (79%) had no or minor structural disease. During 7.0 (IQR: 4.5 to 9.4) years of follow-up, 49 patients (43%) with no or minor structural disease at inclusion developed new structural criteria being defined as progressors. Among 80 participants with no or minor structural disease and no arrhythmic history at inclusion, a first arrhythmic event occurred in 14 (17%). The incidence of arrhythmic events was higher in progressors (11/27, 41%) than in non-progressors (3/53, 6%) (p<0.001) (Figure). Structural progression was associated with higher risk of first arrhythmic events during follow-up when adjusted for sex, age at inclusion and follow-up duration, independent of electrical progression (7.6, 95% CI [1.5, 37.2], P=0.01).

Incident arrhythmic events distribution

Conclusion

Almost half of patients without overt structural cardiac disease at genetic diagnosis develop new structural criteria during 7 years follow-up and 17% experienced their first ventricular arrhythmic event. Structural progression was independently associated with ventricular arrhythmic events during follow-up. These findings highlight the increased risk of arrhythmias when structural abnormalities are detected. Their finding may initiate the evaluation for primary prevention cardioverter-defibrillator implantation.

P2452Application of left atrial strain for differentiation between pre- and post-capillary pulmonary hypertension

Background

Pulmonary hypertension (PH) is classified as pre- or post-capillary PH, and pulmonary capillary wedge pressure (PCWP) >15 mmHg is used as criterion for post-capillary PH. Elevated left atrial (LA) pressure is associated with reduced LA reservoir strain. Thus, LA strain may potentially serve to differentiate between these diagnoses.

Objectives

This study tested the hypothesis that LA strain can be used as a noninvasive parameter to differentiate between pre- and post-capillary PH.

Methods

We analyzed 103 patients (mean age: 58 years, 51 female) referred to right heart catheterization due to unexplained dyspnea or suspected heart failure. Echocardiography was performed within 24 hours of the invasive procedure. Mean pulmonary artery pressure (PAP) was noninvasively estimated from tricuspid regurgitation (TR) velocity and inferior vena cava (IVC) diameter and collapsibility. LA reservoir strain was calculated from apical four-chamber view by speckle tracking echocardiography, and was feasible in 101 patients.

Results

Twenty-eight patients were invasively confirmed with pre-capillary PH and 43 patients with post-capillary PH. The remaining 32 patients had no PH. LA reservoir strain was significantly lower in patients with post-capillary PH than patients with pre-capillary PH (9.9±5.5% vs. 24.6±8.2%, p<0.01). At a cut-off value of 15.4%, LA reservoir strain could predict elevated PCWP >15 mmHg with AUC=0.88, sensitivity=84.8% and specificity=81.8%. As shown in the figure, echocardiography with LA reservoir strain correctly differentiated 82% of patients into pre- and post-capillary PH.

Conclusions

These results suggest that LA reservoir strain can be used to predict elevated PCWP, thus allowing discrimination between pre- and post-capillary PH.

P1480Left atrial strain improves estimation of left ventricular filling pressure

Background

The current algorithm in the 2016 recommendations for echocardiographic estimation of left ventricular filling pressure (LVFP) as normal or elevated, combines traditional indices of mitral inflow velocities, tissue Doppler, left atrial volume and tricuspid regurgitation velocity (Figure A). Some of the patients remain unclassified by this algorithm. Left atrial (LA) strain is a novel index that correlates well with LVFP and may improve estimation of LVFP in these patients.

Purpose

We tested if LA strain can improve estimation of LVFP for the patients that are unclassified by the 2016 algorithm.

Methods

We analyzed data from 100 patients who were referred to right heart catheterization due to unexplained dyspnea or suspected heart failure. Echocardiography was performed simultaneously with or within 24 hours of right heart catheterization. Pulmonary capillary wedge pressure (PCWP) was used as an estimate for LVFP and defined as elevated if above 12 mmHg. Elevated LVFP was first estimated using the 2016 algorithm. In patients who were unclassified by the algorithm due to conflicting indices or unattainable indices, LA strain was subsequently used to detect elevated LVFP using a cut-off found from ROC analysis of the whole cohort.

Results

Six patients were unclassified by the 2016 algorithm. The ROC analysis of all 100 patients showed that at an LA strain cut-off of above or below 16.2%, LVFP was correctly classified as normal or elevated, respectively, with a sensitivity of 83% and specificity of 88%. All 6 unclassified patients by the 2016 algorithm were correctly classified using the LA strain cut-off, effectively increasing the accuracy of the algorithm by 6 percentage points.

Conclusions

LA strain may have a role in non-invasive estimation of LVFP, particularly in patients who remain unclassified when using the conventional echocardiographic indices.

Acknowledgement/Funding

South-Eastern Norway Regional Health Authority

P2458Restricted left atrial motion as a result of atrial stiffening in patients with cardiac amyloidosis

Background

Left atrial (LA) involvement of abnormal amyloid fibrils could induce LA dysfunction and stiffening in patients with cardiac amyloidosis (CA). Thus, the assessments of LA function and stiffness might be a potential approach to diagnose CA phenotype among patients with hypertrophied hearts.

Purpose

We sought to determine whether LA reservoir strain with speckle tracking echocardiography could be used a marker of LA stiffness in a derivation cohort. Furthermore, we tested to our hypothesis that LA reservoir strain could differentiate CA patients from hypertrophic cardiomyopathy (HCM) in an independent validation cohort.

Methods

In the derivation cohort, echocardiography was performed simultaneously with measurements of pulmonary capillary wedge pressure (PCWP) in 50 patients with suspected or established heart failure and relatively preserved left ventricular (LV) ejection fraction (56±10%). LA maximum and minimum volume index, and reservoir strain were measured from apical four-chamber view. LA stiffness index was computed as a pressure rise from x-trough to v-wave divided by an increase from minimum to maximum indexed LA volume (Figure A). In an independent validation group, we studied a total of 33 biopsy-proved CA patients and 127 HCM patients (LV ejection fraction: 57±11% vs. 66±10%, P<0.01) in sinus rhythm on the date of comprehensive echocardiographic study. Among them, cardiac magnetic resonance imaging (CMR) could be evaluated in 17 CA patients and 98 HCM patients. Furthermore, right heart catheterization was performed with 12 CA patients and 12 HCM patients in the CMR group.

Results

The derivation cohort study found that there was a significant curvilinear correlation of LA reservoir strain to LA stiffness index (Figure B). In the validation cohort, LA reservoir strain was reduced in patients with CA compared with HCM in all participants (11.6±5.6% vs. 18.5±6.9%, P<0.01), although there was no significant difference of LA maximal volume index between 2 groups (37±16 ml/m2 vs. 37±12 ml/m2, p=0.89). In the CMR group, the late gadolinium enhancement was observed in the LA wall in 16 patients with CA (94.1%) as shown in Figure C. In contrast, the LA enhancement revealed only in 1 patient with HCM (1.0%). Among patients with invasive measures, LA stiffness index [median (interquartile range)] was higher in patients with CA than that in patients with HCM [1.1 (0.4–2.8) vs. 0.2 (0.1–0.6), P=0.01].

Conclusions

LA reservoir function was fairly limited in patients with CA compared with HCM. Restricted LA motion might be related to atrial amyloid deposits or fibrosis, which potentially provokes atrial chamber stiffening.

P2562Changes in the electrocardiographic/mechanical relation may explain the low risk of arrhythmia during moderate hypothermia

Introduction

Hypothermia is therapeutically used after cardiac arrest. The moderate hypothermia alters cardiac function, with reduced heart rate (HR), prolonged systolic duration and increased QT interval. The risk of arrhythmia increases with prolonged QT-interval, but clinical studies have not been able to demonstrate an increase of arrhythmic events during moderate hypothermia. The mechanism of this is not thoroughly described, but the concurrent increase in mechanical systolic duration may play a part of the explanation.

Purpose

QT prolongation and increased electromechanical window (EMW) negativity; the duration of left ventricle mechanical systole relatively to the duration of the electrical systole, are associated with arrhythmia. We hypothesized that moderate hypothermia would increase ECG intervals and systolic duration without an increase in EMW negativity.

Methods

In an open-chest porcine model (n=10), 2D echocardiography measurements and Doppler recordings were performed with concurrent 3-lead ECG registrations during normothermia (38°C) and moderate hypothermia (33°C) at spontaneous HR. Diastolic and systolic durations were assessed by valve opening to valve closure and Doppler assessed ejection time (ET). Isovolumetric contraction time (IVCT) and EMW, were measured. Systolic function was assessed by ejection fraction (EF), stroke volume (SV) and systolic velocity (s'). Results are presented as means ± SD. Two-sided T-test was used for comparison and P-value <0.05 was considered significant.

Results

Moderate hypothermia reduced HR from 91±9 to 82±7 beats/min (p<0.0001) and increased QT and QT-corrected (QTc) intervals, the latter from 484±52 to 555±50 ms (p<0.0001). Systolic duration increased as ET was prolonged from 293±15 to 397±39 ms (p<0.0001). There was a reduction in systolic velocity (s') (p=0.003) but a non-significant reduction in EF and SV. EMW changed from a negative to a positive value, −49±57 to 9±53 ms (p=0.017) during moderate hypothermia.

Conclusion

Moderate hypothermia increased the QTc-interval but the mechanical systolic duration was even more prolongated. The EMW became positive demonstrating that the mechanical systole outlasted the electrical systole. As less EMW negativity is considered to be protective regarding arrhythmia, these findings may explain why arrhythmia is not frequently occurring during moderate hypothermia.

Acknowledgement/Funding

None

Complement factor 5 blockade reduces porcine myocardial infarction size and improves immediate cardiac function

Inhibition of complement factor 5 (C5) reduced myocardial infarction in animal studies, while no benefit was found in clinical studies. Due to lack of cross-reactivity of clinically used C5 antibodies, different inhibitors were used in animal and clinical studies. Coversin (Ornithodoros moubata complement inhibitor, OmCI) blocks C5 cleavage and binds leukotriene B4 in humans and pigs. We hypothesized that inhibition of C5 before reperfusion will decrease infarct size and improve ventricular function in a porcine model of myocardial infarction. In pigs (Sus scrofa), the left anterior descending coronary artery was occluded (40 min) and reperfused (240 min). Coversin or placebo was infused 20 min after occlusion and throughout reperfusion in 16 blindly randomized pigs. Coversin significantly reduced myocardial infarction in the area at risk by 39% (p = 0.03, triphenyl tetrazolium chloride staining) and by 19% (p = 0.02) using magnetic resonance imaging. The methods correlated significantly (R = 0.92, p < 0.01). Tissue Doppler echocardiography showed increased systolic displacement (31%, p < 0.01) and increased systolic velocity (29%, p = 0.01) in coversin treated pigs. Interleukin-1β in myocardial microdialysis fluid was significantly reduced (31%, p < 0.05) and tissue E-selectin expression was significantly reduced (p = 0.01) in the non-infarcted area at risk by coversin treatment. Coversin ablated plasma C5 activation throughout the reperfusion period and decreased myocardial C5b-9 deposition, while neither plasma nor myocardial LTB4 were significantly reduced. Coversin substantially reduced the size of infarction, improved ventricular function, and attenuated interleukin-1β and E-selectin in this porcine model by inhibiting C5. We conclude that inhibition of C5 in myocardial infarction should be reconsidered.

Myocardial tissue CO2 tension detects coronary blood flow reduction after coronary artery bypass in real-time†

BACKGROUND

Coronary stenosis after coronary artery bypass grafting (CABG) may lead to myocardial ischaemia and is clinically difficult to diagnose. In a CABG model, we aimed at defining variables that detect hypoperfusion in real-time and correlate with impaired regional ventricular function by monitoring myocardial tissue metabolism.

METHODS

Off-pump CABG was performed in 10 pigs. Graft blood flow was reduced in 18 min intervals to 75, 50, and 25% of baseline flow with reperfusion between each flow reduction. Myocardial tissue Pco2 (Pt(CO2)), Po2, pH, glucose, lactate, and glycerol from the graft supplied region and a control region were obtained. Regional cardiac function was assessed as radial strain.

RESULTS

In comparison with baseline, myocardial pH decreased during 75, 50, and 25% flow reduction (-0.15; -0.22; -0.37, respectively, all P<0.05) whereas Pt(CO2) increased (+4.6 kPa; +7.8 kPa; +12.9 kPa, respectively, all P<0.05). pH and Pt(CO2) returned to baseline upon reperfusion. Lactate and glycerol increased flow-dependently, while glucose decreased. Regional ventricular contractile function declined significantly. All measured variables remained normal in the control region. Pt(CO2) correlated strongly with tissue lactate, pH, and contractile function (R=0.86, R=-0.91, R=-0.70, respectively, all P<0.001). New conductometric Pt(CO2) sensors were in agreement with established fibre-optic probes. Cardiac output was not altered.

CONCLUSIONS

Myocardial pH and Pt(CO2) monitoring can quantify the degree of regional tissue hypoperfusion in real-time and correlated well with cellular metabolism and contractile function, whereas cardiac output did not. New robust conductometric Pt(CO2) sensors have the potential to serve as a clinical cardiac monitoring tool during surgery and postoperatively.

Detection of myocardial ischaemia by epicardial accelerometers in the pig

BACKGROUND

We describe a novel technique for continuous real-time assessment of myocardial ischaemia using a three-axis accelerometer.

METHODS

In 14 anaesthetized open-chest pigs, two accelerometers were sutured on the left ventricle (LV) surface in the perfusion areas of the left anterior descending (LAD) and circumflex (CX) arteries. Acceleration was measured in the longitudinal, circumferential, and radial directions, and the corresponding epicardial velocities were calculated. Regional LV dysfunction was induced by LAD occlusion for 60 s. Global LV function was altered by nitroprusside, epinephrine, esmolol, and fluid loading. Epicardial velocities were compared with strain by echocardiography during LAD occlusion and with aortic flow and LV dP/dt(max) during interventions on global LV function.

RESULTS

LAD occlusion induced ischaemia, shown by lengthening in systolic strain in the LV apical anterior region (P<0.01) and concurrent changes in LAD accelerometer circumferential velocities during systole (P<0.01) and during the isovolumic relaxation phase (P<0.01). The changes in accelerometer circumferential velocities during LAD occlusion were greater compared with the changes during the interventions on global function (P<0.01). For the LAD accelerometer circumferential velocities, sensitivity was 94-100% and specificity was 92-94% in detecting ischaemia.

CONCLUSIONS

Myocardial ischaemia can be detected with epicardial three-axis accelerometers. The accelerometer had the ability to distinguish ischaemia from interventions altering global myocardial function. This novel technique may be used for continuous real-time monitoring of myocardial ischaemia during and after cardiac surgery.