Metabolomic Association and Risk Prediction With Heart Failure in Older Adults

BACKGROUND

Older adults have markedly increased risks of heart failure (HF), specifically HF with preserved ejection fraction (HFpEF). Identifying novel biomarkers can help in understanding HF pathogenesis and improve at-risk population identification. This study aimed to identify metabolites associated with incident HF, HFpEF, and HF with reduced ejection fraction and examine risk prediction in older adults.

METHODS

Untargeted metabolomic profiling was performed in Black and White adults from the ARIC study (Atherosclerosis Risk in Communities) visit 5 (n=3719; mean age, 75 years). We applied Cox regressions to identify metabolites associated with incident HF and its subtypes. The metabolite risk score (MRS) was constructed and examined for associations with HF, echocardiographic measures, and HF risk prediction. Independent samples from visit 3 (n=1929; mean age, 58 years) were used for replication.

RESULTS

Sixty metabolites (hazard ratios range, 0.79-1.49; false discovery rate, <0.05) were associated with incident HF after adjusting for clinical risk factors, eGFR, and NT-proBNP (N-terminal pro-B-type natriuretic peptide). Mannonate, a hydroxy acid, was replicated (hazard ratio, 1.36 [95% CI, 1.19-1.56]) with full adjustments. MRS was associated with an 80% increased risk of HF per SD increment, and the highest MRS quartile had 8.7× the risk of developing HFpEF than the lowest quartile. High MRS was also associated with unfavorable values of cardiac structure and function. Adding MRS over clinical risk factors and NT-proBNP improved 5-year HF risk prediction C statistics from 0.817 to 0.850 (∆C, 0.033 [95% CI, 0.017-0.047]). The association between MRS and incident HF was replicated after accounting for clinical risk factors (P<0.05).

CONCLUSIONS

Novel metabolites associated with HF risk were identified, elucidating disease pathways, specifically HFpEF. An MRS was associated with HF risk and improved 5-year risk prediction in older adults, which may assist at at-risk population identification.

Assessment of Prevalence, Clinical Characteristics, and Risk Factors Associated With "Low Flow State" Using Cardiac Magnetic Resonance

Objective

To assess prevalence, clinical characteristics, and risk factors associated with low flow state (LFS) in a multiethnic population with normal left ventricular ejection fraction (LVEF).

Patients and Methods

The study included 4398 asymptomatic participants undergoing cardiac magnetic resonance from July 17, 2000, to August 29, 2002. Left ventricular (LV) mass, volume, and myocardial contraction fraction were assessed. Low flow state was defined as stroke volume index (SVi of <35 mL/m2). Clinical characteristics, cardiac risk factors, and cardiac magnetic resonance findings were compared between LFS and normal flow state (NFS) groups (NFS: SVi of ≥35 mL/m2).

Results

There were significant differences in the prevalence of LFS in different ethnic groups. Individuals with LFS were older (66±9.6 vs 61±10 years; P<.0001). The prevalence of LFS was 19% in the group aged older than 70 years. The logistic multivariable regression analysis found that age was independently associated with LFS. The LFS group had significantly higher prevalence of diabetes (30% vs 24%; P=.001), LV mass-volume ratio (1.13±0.22 vs 0.91±0.15; P<.0001), inflammatory markers, a lower LV mass index (59±10 vs 65±11 kg/m2; P<.001), lower myocardial contraction fraction (58.1±10.6% vs 75.7±13%; P<.001), and a lower left atrial size index (32.2±4.6 vs 36.7±5.9 mm/m2; P<.0001) than NFS.

Conclusion

Low flow state may be considered an under-recognized clinical entity associated with increasing age, multiple risk factors, increased inflammatory markers, a lower LV mass index, and suboptimal myocardial performance despite the presence of normal LVEF and absence of valvular disease.

Quantifying Cardiothoracic Variation with Posture and Respiration to Inform Cardiac Device Design

PURPOSE

With extravascular implantable cardioverter defibrillator leads placed beneath the sternum, it is important to quantify heart motion relative to the rib cage with postural changes and respiration.

METHODS

MRI scans from five males and five females were collected in upright and supine postures at end inspiration [n = 10 each]. Left and right decubitus [n = 8 each] and prone [n = 5] MRIs at end inspiration and supine MRIs at end expiration [n = 5] were collected on a subset. Four cardiothoracic measurements, six cardiac measurements, and six cardiac landmarks were collected to measure changes across different postures and stages of respiration.

RESULTS

The relative location of the LV apex to the nearest intercostal space was significantly different between the supine and decubitus postures (average ± SD difference: - 15.7 ± 11.4 mm; p < 0.05). The heart centroid to xipho-sternal junction distance was 9.7 ± 7.9 mm greater in the supine posture when compared to the upright posture (p < 0.05). Cardiac landmark motion in the lateral direction was largest due to postural movement (range 23-50 mm) from the left decubitus to the right decubitus posture, and less influenced by respiration (5-17 mm). Caudal-cranial displacement was generally larger due to upright posture (13-23 mm caudal) and inspiration (7-20 mm cranial).

CONCLUSIONS

This study demonstrates that the location of the heart with respect to the rib cage varies with posture and respiration. The gravitational effects of postural shifts on the heart position are roughly 2-3 times larger than the effects of normal respiration.

Integrating Measures of Myocardial Fibrosis in the Transition from Hypertensive Heart Disease to Heart Failure

PURPOSE OF REVIEW

This review aims to summarize recent developments in identifying and quantifying both the presence and amount of myocardial fibrosis by imaging and biomarkers. Further, this review seeks to describe in general ways how this information may be used to identify hypertension and the transition to heart failure with preserved ejection fraction.

RECENT FINDINGS

Recent studies using cardiac magnetic resonance imaging highlight the progressive nature of fibrosis from normal individuals to those with hypertension to those with clinical heart failure. However, separating hypertensive patients from those with heart failure remains challenging. Recent studies involving echocardiography show the subclinical myocardial strain changes between hypertensive heart disease and heart failure. Lastly, recent studies highlight the potential use of biomarkers to identify those with hypertension at the greatest risk of developing heart failure. In light of the heterogeneous nature between hypertension and heart failure with preserved ejection fraction, an integrated approach with cardiac imaging and biomarker analysis may enable clinicians and investigators to more accurately characterize, prevent, and treat heart failure in those with hypertension.

The Simulated Cardiology Clinic: A Standardized Patient Exercise Supporting Medical Students' Biomedical Knowledge and Clinical Skills Integration

INTRODUCTION

Development of cardiac disease-related diagnostic skills-including hypothesis-driven data gathering, heart sound interpretation, and ECG interpretation-is an important component of medical student training. Prior studies indicate trainees' performance of these skills is limited. Simulation provides students with opportunities to practice integrating their developing knowledge in a relevant clinical context. We developed a simulated clinic activity for second-year medical students consisting of standardized patient (SP) cases representing cardiovascular (CV) diseases.

METHODS

Student small groups rotated through four SP encounters. For each case, one student performed the history, after which the whole small group listened to audio files of heart sounds, interpreted an ECG, and collaboratively developed a prioritized differential diagnosis. The CV course director met with students for a large-group debrief, highlighting key learning points. We collected learners' evaluations of the event through an online survey.

RESULTS

Of students, 276 participated in this activity over the course of 2 years. Nearly all students assessed the activity as extremely or quite effective for applying learning content from the CV course (97%, 2018; 93%, 2019), and for practicing how to approach chest pain, shortness of breath, palpitations, and fatigue (100%, 2018; 95%, 2019). The most helpful aspects were reinforcement of CV disease illness scripts, hypothesis-driven data gathering practice, ECG interpretation, and applying knowledge and skills in a realistic context.

DISCUSSION

SP encounters representing CV conditions can effectively provide opportunities for students to integrate basic science knowledge and clinical skills. Students assessed the activity as helpful and engaging.

Asymptomatic myocardial ischemia forecasts adverse events in cardiovascular magnetic resonance dobutamine stress testing of high-risk middle-aged and elderly individuals

BACKGROUND

Current guidelines for assessing the risk of experiencing a hospitalized cardiovascular (CV) event discourage stress testing of asymptomatic individuals; however, these recommendations are based on evidence gathered primarily from those aged < 60 years, and do not address the possibility of unrecognized "silent myocardial ischemia" in middle aged and older adults.

METHODS

We performed dobutamine cardiovascular magnetic resonance (CMR) stress testing in 327 consecutively recruited participants aged > 55 years without CV-related symptoms nor known coronary artery disease, but otherwise at increased risk for a future CV event due to pre-existing hypertension or diabetes mellitus for at least 5 years. After adjusting for the demographics and CV risk factors, log-rank test and Cox proportional hazards models determined the additional predictive value of the stress test results for forecasting hospitalized CV events/survival. Either stress-induced LV wall motion abnormalities or perfusion defects were used to indicate myocardial ischemia.

RESULTS

Participants averaged 68 ± 8 years in age; 39% men, 75% Caucasian. There were 38 hospitalized CV events or deaths which occurred during a mean follow-up of 58 months. Using Kaplan-Meier analyses, myocardial ischemia identified future CV events/survival (p <  0.001), but this finding was more evident in men (p <  0.001) versus women (p = 0.27). The crude hazard ratio (HR) of myocardial ischemia for CV events/survival was 3.13 (95% CI: 1.64-5.93; p < 0.001). After accounting for baseline demographics, CV risk factors, and left ventricular ejection fraction/mass, myocardial ischemia continued to be associated with CV events/survival [HR: 4.07 (95% CI: 1.95-8.73) p < 0.001].

CONCLUSIONS

Among asymptomatic middle-aged individuals with risk factors for a sentinel CV event, the presence of myocardial ischemia during dobutamine CMR testing forecasted a future hospitalized CV event or death. Further studies are needed in middle aged and older individuals to more accurately characterize the prevalence, significance, and management of asymptomatic myocardial ischemia.

TRIAL REGISTRATION

( ClinicalTrials.gov identifier): NCT00542503 and was retrospectively registered on October 11th, 2007.

Unexpected Finding: Aortic Regurgitation in a Case of Severe Migraine Headaches

The relationship between migraine headaches and valvular heart disease usually relates to chronic use of ergotamine-based medical therapies. Significant aortic regurgitation can result in decreased global cerebral perfusion, and for patients with migraine headaches, decreased cerebral perfusion represents a key finding in relation to their symptomatology from migraines. Though headaches are rarely regarded as complications of aortic regurgitation, a case study is presented of significant aortic regurgitation in an ergotamine-naïve patient whose symptoms resolved after valve replacement surgery.

Early versus late percutaneous revascularization in patients hospitalized with non ST-segment elevation myocardial infarction: The atherosclerosis risk in communities surveillance study

BACKGROUND

Current guidelines recommend early invasive intervention (<24 hr) for high risk patients with non-ST-segment elevation myocardial infarction (NSTEMI). A delayed invasive strategy (24-72 hr) is considered reasonable for low risk patients. The real-world effectiveness of this strategy is unknown.

METHODS

The ARIC Study has conducted hospital surveillance of acute myocardial infarction (MI) since 1987. NSTEMI was classified using a validated algorithm. We limited our study to patients undergoing early (<24 hr of the event onset), or late (≥24 hr) percutaneous coronary intervention (PCI). Patients were stratified into low (TIMI score 2-4), and high risk (TIMI score 5-7, or presence of cardiogenic shock, ventricular fibrillation, or cardiac arrest). Associations between early versus late PCI and mortality were analyzed using multivariable logistic regression adjusted for demographics, hospitalization year, TIMI score, and comorbidities.

RESULTS

From 1987 to 2012, 6,746 patients were hospitalized with NSTEMI and underwent PCI. Most were white (79%), male (68%), with mean age 61 years. The 28-day and 1-year mortality were 2% and 5%, respectively. Most revascularizations (65%) were late. After accounting for potential confounders, early PCI was associated with a 58% reduced 28-day mortality (OR = 0.42; 95% CI: 0.21-0.84) for the entire population, and 57% reduced mortality (OR = 0.43; 95% CI: 0.21-0.88) for high risk patients. By 1-year of follow up, there was no significant difference in mortality with respect to early vs. late PCI.

CONCLUSION

In hospitalized NSTEMI patients with high risk of clinical events, early PCI is associated with improved 28-day survival.

Clinical Outcomes in Different Types of Aortic Stenosis as Assessed by Doppler Echocardiography

BACKGROUND AND AIM OF THE STUDY

Cardiologists continue to struggle with the prognosis and significance of low-gradient, severe aortic stenosis (AS) with preserved ejection fraction (EF). Conflicting data makes more substantive decisions challenging. The study aim was to determine the prognosis and significance of severe AS by reviewing index cases from the authors' echocardiography laboratory.

METHODS

The study included 302 patients with AS and with aortic valve area (AVA) ≤1.0 cm2 who were identified from the echocardiography database between 2010 and 2011. AS was subdivided into four types based on AVA and mean pressure gradient (PG): (i) PG-matched, severe AS (AVA ≤1.0 cm2 and mean PG ≥40 mmHg; n = 143); (ii) low-PG, severe AS (AVA ≤1.0 cm2, mean PG <40 mmHg, and reduced EF <50%; n = 52); (iii) low-PG, severe AS (AVA ≤1.0 cm2, mean PG <40 mmHg, preserved EF ≥50%; n = 107); and patients with moderate AS (mean PG >25 mmHg and AVA ≥1.0 cm2; n = 104).

RESULTS

Among patients medically managed, those with low-PG severe AS and a reduced EF had the worst outcome. Compared to low-PG severe AS with EF ≥50%, patients with a low-PG and severe AS with EF <50%, and with matched-PG severe AS, had an increased risk of death (p <0.001 and p = 0.052, respectively). For gradient-matched severe AS, those patients who were unoperated had a more than five-fold mortality risk compared to those who underwent surgery [Hazard Ratio (HR): 5; p <0.001]. Similarly, among patients with low-PG severe AS with EF ≥50%, those medically managed had a threefold greater mortality risk compared to those who underwent surgery (HR: 3.3; p = 0.002).

CONCLUSIONS

Patients with low-PG severe AS and a preserved EF have a worse survival than those with moderate AS, but survived better than those with gradient-matched severe AS.

Ten-year longitudinal change in aortic stiffness assessed by cardiac MRI in the second half of the human lifespan: the multi-ethnic study of atherosclerosis

AIMS

Longitudinal determinants of aortic stiffness (AS) measured by magnetic resonance imaging (MRI) have not been assessed in a large community-based population. Our aim was to examine the determinants of change in thoracic AS over 10 years of follow-up in a multi-ethnic population of individuals 45 years of age and older measured by MRI.

METHODS AND RESULTS

We studied 1160 participants (mean age = 60 ± 9 years at baseline, 45% male) with aortic MRI at both the MESA Year 0 and Year 10 examinations. Ascending and descending aorta distensibility (AAD/DAD) and aortic arch pulse-wave velocity (PWV) were measured using MRI. Determinants of the change in AS parameters over 10 years were assessed using linear regression adjusted for baseline values, demographic variables, baseline risk factors and change in risk factors, and chronic risk exposure. AAD and DAD decreased slightly (5% decrease in median for AAD: 1.33-1.26 mmHg(-1) · 10(-3), P = 0.008; 5% decrease in median for DAD: 1.73-1.64 mmHg(-1) · 10(-3), P < 0.001), and PWV increased over 10 years (18% increase in median: 6.8-8.0 m/s P < 0.001). Baseline age was related to a reduction in AAD and DAD and an increase in PWV throughout the follow-up period. Baseline and change in mean blood pressure and continued smoking were associated with a reduction in AAD and an increase in PWV. Furthermore, baseline heart rate was also related to a reduction in AAD and DAD. Blood pressure normalization was related to less aortic stiffening throughout the follow-up period.

CONCLUSIONS

In our longitudinal, community-based cohort study of adult individuals aged 45 years or greater, greater mean blood pressure and a history of smoking history were associated with increased aortic stiffening over 10 years as assessed by MRI.

Adiposity Is Associated with Gender-Specific Reductions in Left Ventricular Myocardial Perfusion during Dobutamine Stress

Background

Obesity and visceral adiposity are increasingly recognized risk factors for cardiovascular disease. Visceral fat may reduce myocardial perfusion by impairing vascular endothelial function. Women experience more anginal symptoms compared to men despite less severe coronary artery stenosis, as assessed by angiography. Women and men have different fat storage patterns which may account for the observed differences in cardiovascular disease. Therefore, our objective was to evaluate the relationship between visceral adipose tissue distributions and myocardial perfusion in men and women.

Methods

Visceral and subcutaneous fat distributions and myocardial perfusion were measured in 69 men and women without coronary artery disease using magnetic resonance imaging techniques. Myocardial perfusion index was quantified after first-pass perfusion with gadolinium contrast at peak dose dobutamine stress.

Results

We observed inverse relationships between female gender (r = -0.35, p = 0.003), pericardial fat (r = -0.36, p = 0.03), intraperitoneal fat (r = -0.37, p = 0.001), and retroperitoneal fat (r = -0.36, p = 0.002) and myocardial perfusion index. Visceral fat depots were not associated with reduced myocardial perfusion at peak dose dobutamine in men. However, in women, BMI (r = -0.33, p = 0.04), pericardial fat (r = -0.53, p = 0.02), subcutaneous fat (r = -0.39, p = 0.01) and intraperitoneal fat (r = -0.30, p = 0.05) were associated with reduced myocardial perfusion during dobutamine stress.

Conclusions

Higher visceral fat volumes are associated with reduced left ventricular myocardial perfusion at peak dose dobutamine stress in women but not in men. These findings suggest that visceral fat may contribute to abnormal microcirculatory coronary artery perfusion syndromes, explaining why some women exhibit more anginal symptoms despite typically lower grade epicardial coronary artery stenoses than men.

Clinical significance of intermediate left ventricular trabeculations in cardiac magnetic resonance

OBJECTIVE

Although the clinical importance of left ventricular noncompaction cardiomyopathy (LVNC) is known, few data exist that describe the prognosis associated with intermediate levels of LV trabeculations that do not meet criteria for LVNC.

METHODS

Trabeculation/possible LVNC by CMR was retrospectively observed among 122 consecutive cases. We assessed the end-systolic noncompacted-to-compacted ratios (ESNCCR) along with deaths, embolic events, congestive heart failure (CHF) readmissions, ventricular arrhythmias, myocardial thickening (MT), and ejection fraction (EF). ESNCCRs were categorized as follows: <1, 1<1.5, 1.5<2, ≥2. General linear models were used to compare combined events (death, CHF readmission, embolism, ventricular arrhythmia) between categories of ESNCCR. There were 3 models used: model 1: unadjusted; model 2: adjusted for age, race, gender, body surface area, LV ejection fraction, and trabeculated segments; model 3: model 2+adjustment for myocardial thickening.

RESULTS

In model 1, those with an ESNCCR<1 had a lower association with composite clinical events than those with a ratio between 1.5<2 and those≥2 (P<0.002 and P<0.001, respectively). In model 2, the lower association continued, (P=0.009 and P<0.001, respectively), but in model 3, those with a ratio from 1.5-2 only had a trend towards a higher association with composite clinical events than those with a ratio<1 (P=-0.09). Those with a ratio≥2 continued to have a higher association (P=-0.001).

CONCLUSION

Patients with intermediate trabeculations not meeting criteria for LVNC had a higher association with composite clinical events, but it was mediated by decreased myocardial thickening in the associated compacted layer.

Evaluation and management of left ventricular noncompaction cardiomyopathy

Left ventricular (LV) noncompaction cardiomyopathy (LVNC) is a form of cardiomyopathy in which trabeculations fail to "compact" with the left ventricular endocardium during fetal cardiac development and is classically associated with subsequent impairment of LV function, significant mortality, ventricular dysrhythmias, and embolic phenomena. As awareness and medical imaging quality have improved, it is becoming easier to identify trabeculations that traverse the LV cavity and serve as a distinguishing feature of this disorder. Differentiating true noncompaction from mild increases in trabeculations requires prudent imaging and clinical correlation. This review seeks to discuss the potential methods of evaluating left ventricular trabeculations, the role of increased trabeculations in cardiovascular disease, and how their presence may affect clinical management.

Mitral regurgitation in left ventricular noncompaction cardiomyopathy assessed by cardiac MRI

BACKGROUND AND AIM OF THE STUDY

Previous case reports have described patients with left ventricular noncompaction cardiomyopathy (LVNC) with significant mitral regurgitation (MR). The study aim was to determine if LVNC is associated with MR, as assessed by cardiac magnetic resonance imaging (cMRI).

METHODS

LVNC, assessed with cMRI, was observed retrospectively among 122 consecutive cases, 31 of whom had an end-systolic noncompacted-to-compacted ratio (ESNCCR) ≥ 2. In addition, 40 normal subjects undergoing cMRI and 40 with moderate to severe MR were included as controls. Using cine images, the ESNCCR and left ventricular (LV) and right ventricular (RV) stroke volumes were measured. The mitral regurgitant fraction (MRF) was calculated by dividing the difference between the RV and LV stroke volumes by the LV stroke volume. The total papillary muscle (TPM) area was measured from the mid short-axis view. Adjusting for age, race, gender and body surface area, an analysis of covariance was conducted to determine whether MRF and TPM were associated with ESNCCR ≥ 2. Adjusted means were presented with 95% confidence intervals.

RESULTS

After adjustment, the MRF in patients with ESNCCR ≥ 2 was higher than in controls, but did not differ from that in patients with significant MR (21 ± 6.5% versus 2.7 ± 12% versus 29.2 ± 11%, p = 0.039 and p = 0.3, respectively). Further, patients with ESNCCR ≥ 2 had a lower TPM than normal controls or those with moderate to severe MR (1.89 ± 0.28 cm2 versus 3.6 ± 0.26 cm2 versus 3.7 ± 0.24 cm2; p < 0.001 and p < 0.001, respectively).

CONCLUSION

LVNC is associated with increased MR, as assessed using cMRI. LVNC is also associated with abnormalities in the papillary muscle anatomy, which may predispose to MR.

Comparison of systolic and diastolic criteria for isolated LV noncompaction in CMR

OBJECTIVES

This study used cardiac magnetic resonance (CMR) to compare standard criteria for left ventricular noncompaction (LVNC).

BACKGROUND

LVNC as a distinct cardiomyopathy is supported by a growing number of publications. Echocardiographic and CMR criteria have been established to diagnosis LVNC but have led to concerns of diagnostic accuracy.

METHODS

Trabeculation/possible LVNC by CMR was retrospectively observed in 122 consecutive cases. We compared the standard end-systolic noncompacted-to-compacted ratio (ESNCCR), end-diastolic noncompacted:compacted ratio (EDNCCR), and trabecular mass-to-total mass ratio (TMTMR) along with deaths, embolic events, congestive heart failure (CHF) readmissions, ventricular arrhythmias, myocardial thickening (MT), left ventricular ejection fraction (LVEF), 3-dimensional sphericity index (3DSi), and left ventricular end-diastolic volume index. Adjusting for age, race, sex, body surface area, diabetes mellitus, hypertension, hyperlipidemia, coronary artery disease, and CHF, logistic regression was used to compare combined events (death, CHF readmission, embolism, ventricular arrhythmia) between ESNCCR, EDNCCR, and TMTMR. Adjusting for same covariates except CHF, logistic regression was used to compare the odds of CHF for those who met criteria and those who did not. Using analysis of covariance, adjusted means for LVEF, MT, 3DSi, and left ventricular end-diastolic volume index were generated.

RESULTS

ES criteria had a higher odds ratio (8.6; 95% confidence interval [CI]: 2.5 to 33) for combined events than ED criteria (1.8; 95% CI: 0.6 to 5.8) or TMTMR criteria (3.14; 95% CI: 1.09 to 10.2). The odds ratio of CHF for those who met ESNCCR criteria was 29.4 (95% CI: 6.6 to 125), but the odds ratio of CHF for those who met EDNCCR criteria was 3.3 (95% CI: 1.1 to 9.2). After adjustment, those who met criteria for noncompaction by ESNCCR had a lower LVEF and less MT than those who did not (p = 0.01 and p = 0.003, respectively), but there was no difference between those who met criteria for EDNCCR or the TMTMR criteria and those who did not.

CONCLUSIONS

ES measures of LVNC have stronger associations with events, CHF, and systolic dysfunction than other measures.

Weekly doxorubicin increases coronary arteriolar wall and adventitial thickness

BACKGROUND

Doxorubicin (DOX) is associated with premature cardiovascular events including myocardial infarction. This study was performed to determine if the weekly administration of DOX influenced coronary arteriolar medial and/or adventitial wall thickening.

METHODS

Thirty-two male Sprague-Dawley rats aged 25.1± 2.4 weeks were randomly divided into three groups and received weekly intraperitoneal injections of normal saline (saline, n = 7), or low (1.5 mg/kg to 1.75 mg/kg, n = 14) or high (2.5 mg/kg, n = 11) doses of DOX. The animals were treated for 2-12 weeks, and euthanized at pre-specified intervals (2, 4, 7, or 10+ weeks) to obtain histopathologic assessments of coronary arteriolar lumen diameter, medial wall thickness, adventitial wall thickness, and total wall thickness (medial thickness + adventitial thickness).

RESULTS

Lumen diameter was similar across all groups (saline: 315±34 µm, low DOX: 286±24 µm, high DOX: 242±27 µm; p = 0.22). In comparison to animals receiving weekly saline, animals receiving weekly injections of 2.5 mg/kg of DOX experienced an increase in medial (23±2 µm vs. 13±3 µm; p = 0.005), and total wall thickness (51±4 µm vs. 36±5 µm; p = 0.022), respectively. These increases, as well as adventitial thickening became more prominent after normalizing for lumen diameter (p<0.05 to p<0.001) and after adjusting for age, weight, and total cumulative DOX dose (p = 0.02 to p = 0.01). Animals receiving low dose DOX trended toward increases in adventitial and total wall thickness after normalization to lumen diameter and accounting for age, weight, and total cumulative DOX dose (p = 0.06 and 0.09, respectively).

CONCLUSION

In conclusion, these data demonstrate that weekly treatment of rats with higher doses of DOX increases coronary arteriolar medial, adventitial, and total wall thickness. Future studies are warranted to determine if DOX related coronary arteriolar effects are reversible or preventable, exacerbate the known cardiomyopathic effects of DOX, influence altered resting or stress-induced myocardial perfusion, or contribute to the occurrence of myocardial infarction.

Trabeculated (noncompacted) and compact myocardium in adults: the multi-ethnic study of atherosclerosis

BACKGROUND

A high degree of noncompacted (trabeculated) myocardium in relationship to compact myocardium (trabeculated to compact myocardium [T/M] ratio >2.3) has been associated with a diagnosis of left ventricular noncompaction (LVNC). The purpose of this study was to determine the normal range of the T/M ratio in a large population-based study and to examine the relationship to demographic and clinical parameters.

METHODS AND RESULTS

The thickness of trabeculation and the compact myocardium were measured in 8 left ventricular regions on long axis cardiac MR steady-state free precession cine images in 1000 participants (551 women; 68.1±8.9 years) of the Multi-Ethnic Study of Atherosclerosis cohort. Of 323 participants without cardiac disease or hypertension and with all regions evaluable, 140 (43%) had a T/M ratio >2.3 in at least 1 region; in 20 of 323 (6%), T/M >2.3 was present in >2 regions. A multivariable linear regression model revealed no association of age, sex, ethnicity, height, and weight with maximum T/M ratio in participants without cardiac disease or hypertension (P>0.05). In the entire cohort (n=1000), left ventricular ejection fraction (β=-0.02/%; P=0.015), left ventricular end-diastolic volume (β=0.01/mL; P<0.0001), and left ventricular end-systolic volume (β=0.01/mL; P<0.001) were associated with maximum T/M ratio in adjusted models, whereas there was no association with hypertension or myocardial infarction (P>0.05). At the apical level, T/M ratios were significantly lower when obtained on short- compared with long-axis images (P=0.017).

CONCLUSIONS

A ratio of T/M of >2.3 is common in a large population-based cohort. These results suggest re-evaluation of the current cardiac MR criteria for left ventricular noncompaction may be necessary.

Modification of the effect of glycemic status on aortic distensibility by age in the multi-ethnic study of atherosclerosis

Elevated serum glucose from diabetes mellitus (DM) or impaired fasting glucose shares many mechanisms with aging that decrease aortic distensibility (AD), such as glycation of the extracellular matrix. However, few data compare the simultaneous effects of elevated serum glucose and aging on AD. To study this, we examined the relationship among fasting glucose status, age, and AD in the Multi-Ethnic Study of Atherosclerosis: a multiethnic cohort of individuals aged 45 to 84 years without clinical cardiovascular disease. In the Multi-Ethnic Study of Atherosclerosis, participants with normal fasting glucose (n=2270), impaired fasting glucose (n=870), and DM (n=412) underwent MRI assessment of proximal thoracic aortic distensibility. This sample was 46% male, 42% white, 30% black, 11% Asian, and 17% Hispanic. The relationship among glucose status, age, and AD was analyzed with general linear models by adjusting for factors influential on AD. An interaction term was used to determine whether age modified the effect of glucose status on AD. AD was lowest among those with DM. The interaction term was significant (P=0.024). Comparing participants <65 years of age, AD was different between normal fasting glucose and DM (P<0.01) and between normal fasting glucose and impaired fasting glucose (P=0.02). In those >65 years of age, the fasting glucose group was no longer a significant predictor of AD. Our data indicate that there are overall differences in AD among DM, impaired fasting glucose, and normal fasting glucose. However, age modified the effect of glucose status such that differences between the groups diminished with advancing age.

Left ventricular aneurysm surgery. Determinants of results

Between 1967 and 1983, 154 patients had reduction of left ventricular aneurysms by resection or plication. Seventy percent of patients had predominant angina; the remainder had predominant dyspnoea. Fifty-eight percent had associated coronary bypass grafting. Within the group, there were included 26 patients who had aneurysm resection for dyspnoea and who were evaluated by radionuclide angiography at a mean follow-up of 17 + 11 months. There was a 20% early mortality; this fell to 5% in the latter half of this experience. Patients whose major symptom was angina had a 5% early mortality. Those whose major symptom was severe dyspnoea had an early mortality of 30%. Patients who had aneurysm reduction alone had an early mortality of 17% and those who had associated bypass grafting had an early mortality of 9%. There was a 48% late mortality, attrition occurring at a steady rate and being predominantly due to cardiovascular causes. Of 95 patients available for review between one and thirteen years after operation, 60% were in New York Heart Association (N.Y.H.A.) functional class I, 36% in functional class II and 4% in classes III and IV. In patients whose predominant symptom was dyspnoea, radionuclide studies showed that global left ventricular performance at rest was not significantly changed by operation, despite clinical improvement. Long-term clinical outcome was determined more by pre-operative global ventricular function than by function of the residual contractile segment. Within the whole group, however, both early mortality and symptomatic improvement were more likely in patients with predominant angina.

Profound hypothermia in the treatment of intracranial aneurysms

The management of 40 intracranial aneurysms using profound hypothermia and cardiac arrest are reviewed. The technique is described and the reasons for using this procedure are discussed. It is suggested that this technique is of value in the treatment of giant aneurysms, aneurysms which could not be treated by conventional methods, multiple aneurysms, aneurysms in difficult sites and aneurysms complicated by other hazards, such as vascular anomalies.

Heart valve replacement by porcine aortic valve (Hancock prosthesis)

Glutaraldehyde preservation of heterograft valves has increased their durability. Sixty-nine Hancock prostheses have been implanted, 30 in the mitral position and 39 in the aortic position. Anticoagulants have not been administered. There has been one important thromboembolic complication and periprosthetic mitral incompetence has occurred in three instances, but prosthetic incompetence has not developed. Two asymptomatic aortic diastolic murmurs have been noted. After a follow-up ranging between two and 19 months, it appears that the Hancock prosthesis offers a valuable alternative to mechanical valve replacement and anticoagulants are not required as a routine.

Technical considerations in the use of the membrane oxygenator (Lande'-Edwards) for open heart surgery

Experience has shown that successful cardio-pulmonary bypass depends upon an efficient oxygenator which causes minimum blood damage. Experience with 1,600 Lande'-Edwards membrane oxygenators in more than 1,000 patients has led to the development of a simple and safe routine for their use in open heart surgery. The circuitry, method of preparation for perfusion, and management of perfusion are described in detail.

The influence of duration of circulatory arrest at 20 degrees C on cerebral changes

In infants and piglets subjected to periods of circulatory arrest at 20 degrees C there was close correlation between duration of arrest and delay in return of electroencephalographic activity. Post mortem studies demonstrated histological evidence of brain damage in patients after circulatory arrest at 20 degrees C. Similar histological changes were demonstrated in piglets, including some who had complete E.E.G. and clinical recovery from circulatory arrest.

The peri-operative measurement of cardiac output in infancy by the thermodilution technique

Cardiac output has been measured in infants by thermodilution during and after surgery. A method employing commerically available equipment has been developed. An animal model has been devised whereby right heart outputs of 210 ml to 2240 ml, measured by thermodilution, could be compared with left heart outputs measured by an aortic by-pass. The results of this study suggest that thermodilution is a simple, accurate method for measurement of cardiac output in infancy.

Some advantages of the membrane oxygenator for open-heart surgery

The Lande'-Edwards oxygenator has been used for clinical perfusions on 283 patients. Among these patients we have encountered the full range of congenital and acquired defects and a variance in age from 1 day to adulthood. Data are presented concerning the means and methods of perfusion, the defects involved, and the results of treatment. A comparison has been made between two groups of 20 adults each, one group perfused with a bubble oxygenator (Bently) and the other with the Lande'-Edwards membrane lung. This study showed that platelet function is better preserved by the membrane lung, that hemolysis is less severe, and that postoperative bleeding is reduced. Indirect evidence has been accumulated to suggest that pulmonary, cerebral, and renal function is also better preserved when the membrane lung is employed.

Cerebral effects of circulatory arrest at 20 degrees c in the infant pig

Circulatory arrest at 20° C is used during open heart surgery in infants. It has been stated that significant brain damage does not occur.

Piglets between two and six weeks of age were cooled to 20° C using extracorporeal circulation and a membrane oxygenator. After one hour of circulatory arrest the perfusion system was used to rewarm the animals and restore normal circulation. Electroencephalogram was monitored throughout perfusion and surgery, and repeated on surviving animals on the third, fifth, seventh and tenth postoperative days. On the tenth day the animals were killed by injection of pentobarbitone. Other groups were subjected to

Continuous perfusion at 20° C,

Continuous perfusion at 37° C,

Thoracotomy and cannulation,

Ischaemia, and

Hypoxia. The return of E.E.G. activity was delayed after circulatory arrest compared with those continuously perfused. Lesions were found in the cerebral cortex in all the animals which had circulatory arrest and those subjected to ischaemia and hypoxia. The brains of animals of the other groups were indistinguishable from those killed without any experimental procedure.

Despite apparent recovery, brain damage following hypothermic arrest during open heart surgery remains possible.