High-Density Cobalt Single-Atom Catalysts for Enhanced Oxygen Evolution Reaction

Single atom catalysts (SACs) possess unique catalytic properties due to low-coordination and unsaturated active sites. However, the demonstrated performance of SACs is limited by low SAC loading, poor metal-support interactions, and nonstable performance. Herein, we report a macromolecule-assisted SAC synthesis approach that enabled us to demonstrate high-density Co single atoms (10.6 wt % Co SAC) in a pyridinic N-rich graphenic network. The highly porous carbon network (surface area of ∼186 m² g^-1) with increased conjugation and vicinal Co site decoration in Co SACs significantly enhanced the electrocatalytic oxygen evolution reaction (OER) in 1 M KOH (η₁₀ at 351 mV; mass activity of 2209 mA mg_Co^-1 at 1.65 V) with more than 300 h stability. Operando X-ray absorption near-edge structure demonstrates the formation of electron-deficient Co-O coordination intermediates, accelerating OER kinetics. Density functional theory (DFT) calculations reveal the facile electron transfer from cobalt to oxygen species-accelerated OER.

Scalloped tongue is associated with nocturnal intermittent hypoxia among community-dwelling Japanese: the Toon Health Study

Scalloped tongue is considered as a possible clinical finding of obstructive sleep apnoea (OSA). There are few evidence of the association between scalloped tongue and OSA. To examine the association between scalloped tongue and nocturnal intermittent hypoxia (NIH), a surrogate marker of OSA, among a general Japanese population. Study participants were 398 men and 732 women aged 30-79 years who participated in the Toon Health Study from 2011 to 2014. Scalloped tongue was classified into three categories: none, mild and moderate-to-severe. Moderate-to-severe NIH was defined as the 3% oxygen desaturation index of ≥15 events/h during sleep for one night with pulse oximetry. The multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for moderate-to-severe NIH were calculated according to scalloped tongue categories using a logistic regression model. There were 69 (6·1%) moderate-to-severe NIH cases in this population. The multivariable-adjusted ORs (95% CIs) of moderate-to-severe NIH were 1·59 (0·85-2·95) for mild and 2·39 (1·10-5·17) for the moderate-to-severe scalloped tongue group compared with the group without scalloped tongues. When stratified by overweight status (BMI <25 or ≥25 kg m^-2 ), the respective ORs (95% CIs) were 2·83 (1·06-7·55) and 4·74 (1·28-17·49) among overweight individuals, and 0·94 (0·40-2·70) and 1·52 (0·57-4·05) among non-overweight individuals. Scalloped tongue was associated with higher prevalence of moderate-to-severe NIH among the general Japanese population and this association was more evident in overweight individuals.

Designing Proton Conducting Metal Organic Frameworks

Metal organic frameworks (MOFs) or porous coordination polymers (PCPs) represent a tunable molecular scaffolding that can be adjusted for a breadth of applications. This presentation will concern our efforts towards tailoring MOFs towards making new proton conductors ultimately for fuel cells. A major hurdle in these technologies is an electrolyte capable of conducting protons above 100°C. Higher operating temperatures will enhance electrode kinetics and decrease electrode poisoning among several critical operational benefits. In contrast to the macromolecular approaches typically employed towards these electrolytes, we have used a MOF strategy to generate crystalline networks with acidic pores. These MOFs present options to address higher temperature conduction,1 conduction over 10-2 Scm-1,2 and water stability.3 The emphasis in the talk will concern routes to designing these systems and subsequent challenges in their characterization.

Development of Phosphonate Monoesters Building Units in Metal-Organic Frameworks

The use of predictable coordination geometries and the development of new ligands has allowed supramolecular chemists to design a plethora of new materials. Among these are metal-organic frameworks (MOFs), which are composed of ligands coordinating to metal atoms or clusters to generate a framework with potential porosity. MOFs exemplify supramolecular design strategy as their extended structure and tunable properties allow them to be applied for various applications.1 To date, many MOFs utilize carboxylates as the coordinating group since they have well studied coordination geometries and thus predictable framework topologies. Though there are examples of carboxylate-based MOFs possessing water stability, most do not possess this key feature, hindering their application in industrial settings. Phosphonate monoesters (PMEs) have been investigated as a means to impart water stability to a MOF by kinetically shielding the linker-metal bond with the ester moiety.2 Unfortunately, phosphonate monoesters have relatively unexplored coordination geometries, with most studies focusing on chlodronic acid and its derivatives, which do not typically form porous materials. In an attempt to establish building units based on PMEs, 1,4-benzenediphosphonate monoester ligands have been synthesized, coordinated to Cu(II), and characterized. It was found that while the methyl and ethyl analogues form similar 3-D structures with poor water stability,3 the isopropyl analogue forms a layered material possessing water stability. The isopropyl analogue contains chains of Cu-PME, with the isopropyl esters lying directly above and below the Cu atoms, kinetically shielding this bond from water. This water stable building unit was predicted to generate a porous framework with non-linear ligands. To test this hypothesis, 1,3,5-benzenetriphosphonate monoisopropyl ester was synthesized and coordinated to Cu(II). Unfortunately, no single crystal of sufficient quality has been produced, though a predicted and refined structure matches well to various characterization techniques. As predicted, this material is porous and does not degrade in harsh humid conditions (353K and 90% relative humidity).

Force pattern of hypoxic myocardium applied to oxygenated muscle preparations: comparison with effects of regional ischemia on the contraction of non-ischemic myocardium

OBJECTIVE

To examine the basis for local wall motion abnormalities commonly seen in patients with ischemic heart disease, computer-controlled isolated muscle studies were carried out.

METHODS

Force patterns of physiologically sequenced contractions (PSCs) from rat left ventricular muscle preparations under well-oxygenated conditions and during periods of hypoxia and reoxygenation were recorded and stored in a computer. Force patterns of hypoxic-reoxygenating and oxygenated myocardium were applied to oxygenated and hypoxic-reoxygenating myocardium, respectively.

RESULTS

Observed patterns of shortening and lengthening closely resemble those obtained from ischemic and non-ischemic myocardial segments using ultrasonic crystals in intact dog hearts during coronary occlusion and reperfusion, and are similar to findings reported in angiographic studies of humans with coronary artery disease.

CONCLUSION

The current study, demonstrating motions of oxygenated isolated muscle preparations which are similar to those in perfused segments of intact hearts with regional ischemia, supports the concept that the multiple motions of both ischemic and non-ischemic segments seen in regional myocardial disease can be explained by interactions of strongly and weakly contracting muscle during the physiologic cardiac cycle.

Postparturient change in endotoxin levels of ruminal fluid and serum in dairy cows

The changes in the endotoxin levels of ruminal fluid and serum in postparturient cows were evaluated. Five cows were fed hay and concentrates on an individual basis (farm A) and the other 5 cows were given complete feed ad libitum (farm B) after parturition. Ruminal pH levels decreased in both groups after parturition. Subsequently, the ruminal endotoxin levels increased with the declining pH on both of the farms. The ruminal endotoxin levels were slightly higher in cows of farm B than those of farm A. Serum endotoxin levels also showed episodic fluctuations, however, there were no parallel changes between the endotoxin levels of the ruminal fluid and sera.

Empiric determination of the transition from concentric hypertrophy to congestive heart failure in essential hypertension

OBJECTIVES

Our aim was to determine whether there is a final transition from left ventricular hypertrophy to congestive heart failure in the late stage of essential hypertension.

BACKGROUND

A theoretic model using the concept of systolic transmural nonuniform wall thickening was applied to develop a concentric two-shell geometry allowing evaluation of the mechanics of circumferential midwall fibers.

METHODS

We evaluated pressure-volume data from 46 normal control subjects (control group) and 70 patients with hypertension: 33 without hypertrophy (hypertension only group), 14 with hypertrophy (hypertrophy group) and 23 with heart failure in addition to hypertrophy (heart failure group).

RESULTS

End-diastolic volume index was higher in the heart failure group than in the control group (p < 0.01). Although left ventricular wall thickness and mass index were increased in both the hypertrophy and the heart failure group, concentricity indexes as assessed by ratios of left ventricular wall thickness to dimension and mass index to end-diastolic volume index were maximal in the former. Although endocardial and standard midwall fractional shortening did not differ among the control, hypertension only and heart failure groups, that of the modified midwall by concentric two-shell geometry was decreased in the hypertrophy and the heart failure groups (p < 0.05). The Hotelling T2 test and Mahalanobis distance clearly discriminated the latter two groups with end-systolic stress and modified midwall fractional shortening relation.

CONCLUSIONS

A fitting segmented regression model predicted a progression to hypertrophy and identified a transition from hypertrophy to heart failure by a combination of modified midwall fractional shortening and concentricity indexes.

Sclerosing stromal tumour in a cow

A case of sclerosing stromal tumour in an 8-year-old cow is described. The left ovary was entirely replaced by neoplastic tissue, whose features were pseudolobulation of cellular areas, intercellular oedema and calcified plaques. The neoplastic cells varied in morphology and were similar to ovarian stromal cells, theca cells or lutein cells. Immunohistochemically, S-100 protein, oestradiol and testosterone were detected in theca-like or luteinized cells, some of which had ultrastructural features suggestive of steroid hormone synthesis. In contrast, desmin and actin characterized slender spindle cells. This is the first report of a sclerosing stromal tumour in cattle.

Histopathological findings of the digits in dairy cows in Japan

Two hundred and thirty-nine digits of 45 Holstein dairy cows, which were raised in typical Japanese dairy farms and received poor hoof management, were randomly obtained in the slaughterhouses and examined histopathologically. The findings were classified into 5 grades on the basis of the severity of circulatory disturbances and of keratogenesis. The lesions from Grade 1 to 5 were considered as manifestations of serial lesions indicating that subclinical laminitis advanced to other hoof lesions. The incidence of Grade 2, regarded as subclinical laminitis, reached approximately 50% of digits examined. The lesions classified as Grades 3 (23.9%) and 4 (5.4%) were mainly characterized by circulatory disturbances, which were similar to those of chronic laminitis in the previous reports. The incidence of Grade 5, characterized by sole ulcer, was 5.4%. It is suggested that a considerable number of daily cows in Japan suffered from subclinical laminitis, which may be the cause of recent high incidence of hoof diseases in dairy cows.

Left ventricular midwall mechanics in systemic arterial hypertension. Myocardial function is depressed in pressure-overload hypertrophy

BACKGROUND

Left ventricular (LV) midwall geometry has been described conventionally as the sum of the chamber radius and half of the wall thickness; this convention is based on the assumption of uniform transmural thickening during systole. However, theoretical considerations and experimental data indicate that the inner half (inner shell) of the LV wall thickens more than the outer half (outer shell). Thus, an end-diastolic circumferential midwall fiber exhibits a relative migration toward the epicardium during systole. As a result, the conventional method provides an overestimate of the extent of the midwall fiber shortening.

METHODS AND RESULTS

We developed an ellipsoidal model with a concentric two-shell geometry (nonuniform thickening) to assess midwall fiber length transients throughout the cardiac cycle. This modified midwall method was used in the analysis of LV cineangiograms from 15 patients with systemic arterial hypertension and 14 normal subjects. Study groups were classified according to LV mass index (LVMI): 14 normal subjects (group I), eight hypertensive patients with a normal LVMI (group II), and seven hypertensive patients with an increased LVMI (group III). There were no significant differences in LV end-diastolic pressure or volume among the three groups; the ejection fraction was slightly greater in group II (70 +/- 5%) than in groups I (65 +/- 8%) and III (66 +/- 4%), but this trend did not achieve statistical significance. Values for endocardial and conventional midwall fractional shortening (FS) were also similar in the three groups. By contrast, FS by the concentric two-shell geometry (modified midwall method) in group III (16 +/- 2%) was significantly less than that seen in groups I and II (21 +/- 4% and 21 +/- 5%, respectively; both p less than 0.05). This difference achieves greater importance when it is recognized that mean systolic circumferential stress was lower in group III (151 +/- 22 g/cm2) than in groups I and II (244 +/- 37 g/cm2 and 213 +/- 38 g/cm2, respectively; both p less than 0.01). The midwall stress-shortening coordinates in six of the seven group III patients were outside the 95% confidence limits for the normal (group I) subjects. Thus, despite a normal ejection fraction, systolic function is subnormal in hypertensive patients with LV hypertrophy.

CONCLUSIONS

Chamber dynamics provide an overestimate of myocardial function, especially when LV wall thickness is increased. This is due to a relatively greater contribution of inner shell thickening in pressure-overload hypertrophy.

Clinical assessment of left ventricular systolic function by force-length and stress-shortening relationships

Left ventricular (LV) systolic function was assessed in patients with hypertensive heart disease (HHD, n = 30), hypertrophic cardiomyopathy (HCM, n = 27), dilated cardiomyopathy (DCM, n = 25), volume overload heart (VOH, n = 31) and normal subjects (NS, n = 32) in the two-dimensional framework of force-length (end-systolic stress-end-systolic volume index) and stress-shortening (mid-systolic stress-ejection fraction). Quadratic discriminant analysis revealed that the ellipses of confidence of HHD and normal subjects were in the same place with regard to both force-length and stress-shortening, while all other groups were well-discriminated. Three subgroups of patients, those with DCM with mild heart failure and those with VOH (with and without heart failure), were easily distinguishable on the basis of stress-shortening, but not on the basis of force-length measurements. It is concluded that LV systolic function and afterload are maintained within the normal range under pressure and volume overload until symptoms of heart failure appear via the mechanism of compensatory hypertrophy. Stress-shortening appears to be a more useful parameter than force-length for the analysis of LV systolic function in clinical practice.

Square root sign of left ventricular diastolic pressure curve in atrial septal defect

The square root (dip and plateau) sign was observed in 7 of 21 adult patients with atrial septal defect (ASD). This study evaluated left ventricular (LV) diastolic filling dynamics and hemodynamic findings in 7 patients (Group 1) with, and 14 patients (Group 2) without the square root sign; 10 normal subjects (Group 3) served as controls. No significant differences were observed in LV end-diastolic and end-systolic volumes, ejection fraction, or left to right shunt. In Group 1, 77% of LV filling was completed in the first half of diastole; this percentage was 49% and 53% in Groups 2 and 3, respectively (both p less than 0.01 versus Group 1). Early diastolic filling velocity (at 20% of diastole) in Group 1 was significantly greater, and late diastolic filling velocity (at 80% and 90% of diastole) was reduced in Group 1 compared to those in Groups 2 and 3 (all p less than 0.05). The average values for right and left ventricular end-diastolic pressures were significantly higher in Group 1 (11 +/- 2 and 10 +/- 4 mmHg, p less than 0.05) than Group 2 (7 +/- 2 and 7 +/- 2 mmHg, p less than 0.05). It is suggested that a constrictive pathophysiology due to 4 chambers interaction or right ventricular constraint may play a role in the genesis of the square root sign in ASD.

Spectrum of restrictive cardiomyopathy: report of the national survey in Japan

This report describes clinical profiles and echocardiographic, hemodynamic, and histologic findings in 26 cases of idiopathic RCM based on the diagnostic criteria of (1) heart failure resulting from a stiff left ventricle, (2) normal LV size and systolic function, (3) absence of LV hypertrophy, and (4) cause or association unknown. There were 14 male and 12 female patients ranging in age from 5 to 63 years. Ten patients died during the mean follow-up period of 145 months, and five died of heart failure after 10 years. Three had a family history of HCM. Thromboembolism was observed in eight. Echocardiograms showed normal LV wall thickness and contraction. Hemodynamic characteristics included elevated biventricular filling pressures and a pulmonary wedge pressure that was usually higher than the right atrial pressure. Equalization of biventricular filling pressures was seen, however, in almost all patients with severe tricuspid regurgitation (seven of eight). The square root sign was seen in 50% in RV diastolic pressure tracings and 28% in LV tracings. This sign was observed in patients with elevated filling pressures. Interstitial fibrosis (22 of 23), endocardial thickening (13 of 23), and myofibrillar hypertrophy (10 of 23) were common histologic findings. Severe myocardial fiber disarray consistent with HCM was seen in four patients.

An assessment of left ventricular systolic function in pressure and volume overload heart with two shell compartment model of ellipsoid revolution

Left ventricular (LV) midwall mechanics were evaluated in normal, pressure overload due to hypertension, and volume overload hearts due to aortic (AR) and mitral regurgitations (MR) using a 2 shell compartment model of ellipsoid revolution. While ejection fraction (EF) was in the normal range, midwall fractional shortening (MFS) was depressed with low end-diastolic and end-systolic stress in hypertrophied hearts with pressure overload. Not only LV volumes but also LV systolic pressure and wall thickness were increased in AR. LV end-diastolic pressure was elevated, and EF and MFS were reduced in patients with AR and congestive heart failure (CHF). In patients with MR and CHF, pulmonary capillary wedge pressure was elevated, LV volumes were enlarged and end-systolic stress was high, but LV wall thickness and MFS remained in the normal range. It is concluded from this observation that: 1) myocardial contractility is already depressed with normal systolic function in hypertrophied ventricle with pressure overload. 2) AR can be considered to be the disease of both pressure and volume overload, and symptoms of CHF are the result of depressed myocardial contractility. 3) MR is the disease of pure volume overload. Myocardial contractility is well preserved even with the presence of severe CHF in MR.

Optimal timing for valve replacement in chronic aortic regurgitation: analysis based on the myocardial contractility and postoperative prognosis

Left ventricular (LV) function was evaluated considering force-velocity and stress-shortening relationships in 14 asymptomatic (Group 1), 18 symptomatic patients (Group 2), and 53 normal subjects (Group 3) to determine the optimal time for valve replacement in patients with chronic aortic regurgitation (AR). Valve replacement was recommended for all Group 2 patients and for one patient in Group 1, who had sustained ventricular tachycardia. There was one operative death and five deaths remote from surgery; one patient in Group 1 died suddenly of undetermined cause, and four patients in Group 2 died of congestive heart failure (CHF). The LV end-systolic volume index (ESVI) was greater than 100 ml/m2 in the five patients whose death was unrelated to surgery (remote deaths). ESVI was less than 50 ml/m2 in all but two patients in Group 1, and more than 40 ml/m2 in all cases in Group 2. The index of preload, end-diastolic stress (sigma ed), was increased in Groups 1 and 2 as compared with Group 3. A significant positive correlation was observed between end-systolic stress (sigma es) and ESVI (r = 0.71, p less than 0.001) in patients with AR, and this linear line was not as steep as that of Group 3. Afterload (sigma es) and ejection fraction (EF) in Group 1 were within normal range, afterload was normal but EF was reduced in mildly symptomatic patients in Group 2, and severely symptomatic patients had markedly reduced EF and elevated afterload. There was a close correlation between ESVI and end-diastolic volume index (EDVI), and this was expressed as an exponential curve (Y = 21.69e0.006x, r = 0.88, p less than 0.001). This indicates that the rate of shortening of the muscle fiber deteriorates exponentially with enlargement of the ventricle. These observations suggest that in AR patients: 1) afterload and contractility of the ventricle remain normal in the majority of asymptomatic patients by means of compensatory hypertrophy and preload elevation (preload reserve), 2) deterioration of contractility seems to be the factor initiating CHF, and 3) progression of CHF is due to further deterioration of contractility in addition to elevation of afterload (afterload mismatch). It is concluded that careful observations are necessary when ESVI exceeds 50 ml/m2 in asymptomatic patients. Valve replacement is recommended when such patients develop symptoms of CHF, or either when EF falls to less than 50% or ESVI exceeds 100 ml/m2, even if patients remain asymptomatic.

Depressed myocardial contractility in mitral stenosis--an analysis by force-length and stress-shortening relationships

To determine whether low ejection fraction (EF) in mitral stenosis (MS) is the result of depressed contractility or is mediated by other factors, left ventricular (LV) function was analyzed by force-length and stress-shortening relationships. Thirty patients without heart disease served as normal controls (Group 1). Forty-three patients with MS were divided into 2 subgroups: Group 2 (n = 19) had EF within one standard deviation of the mean of Group 1, and Group 3 (n = 24) had EF below it. Normal EF (Group 2) was associated with low preload (end-diastolic stress) and low afterload (end-systolic stress), and preload and afterload were in the normal range in patients with low EF (Group 3). A significant negative correlation was observed in the whole group of patients with MS between EF and end-systolic stress (Y = -0.14X + 72.8, r = -0.61, p less than 0.001), and a positive correlation between end-systolic stress and volume (Y = 1.39X + 65.4, r = 0.45, p less than 0.01). These observations suggest that systolic shortening and end-systolic volume of the left ventricle are in part governed by afterload in this disease. It is concluded that low EF of MS is not mediated by reduced preload or inappropriately elevated afterload, and contractility of the ventricle is mildly depressed in MS.

Right ventricular pacing reduces the rate of left ventricular relaxation and filling

Right ventricular pacing alters left ventricular synchrony and loading conditions, each of which may independently influence left ventricular relaxation. Addition of a properly timed atrial contraction by using sequential atrioventricular (AV) pacing minimizes changes in left ventricular loading conditions, but ventricular asynchrony persists. To separate the effects of altered loading from those of asynchrony, the effects of right ventricular pacing and sequential AV pacing on the rate of isovolumic pressure decline (relaxation time constant), myocardial (segment) lengthening rate and chamber (minor axis dimension) filling rate were examined. In 12 open chest anesthetized dogs, left ventricular pressure (micromanometer) and either left ventricular free wall segment length transients (n = 6) or minor axis dimension transients (n = 6) were measured during right atrial, right ventricular and sequential AV pacing; length and dimension were measured using ultrasonic crystals. Compared with right atrial pacing, right ventricular pacing produced a decrease in systolic pressure, a reduction in fractional shortening, a prolongation of the relaxation time constant (23.5 +/- 0.7 to 29.8 +/- 0.8 ms, p less than 0.05), slower peak segment lengthening rate (6.2 +/- 0.6 to 4.6 +/- 0.8 s-1, p less than 0.05) and a slower rate of increase in chamber dimension (3.5 +/- 0.1 to 2.7 +/- 0.1 s-1, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Functional and histopathologic correlation in patients with dilated cardiomyopathy: an integrated evaluation by multivariate analysis

To correlate left ventricular function and histologic features in patients with dilated cardiomyopathy, precise indexes of hemodynamics and semiquantitative histologic data were combined for multivariate analysis. Right endomyocardial biopsy was performed at the time of cardiac catheterization. Five hemodynamic indexes were used for functional assessment: ejection fraction, ratio of end-systolic stress to volume index, end-diastolic stress, time constant (T) of left ventricular pressure fall, and end-systolic stress. Six histologic findings (disarray of myofibers, hypertrophy of myofibers, scarcity of myofibrils, nuclear changes of myofibers, vacuolization of myofibers and proliferation of collagen fibers) were graded from (-) to (4+). Each finding was assigned to category (-) or (+) according to the absence or presence of significant abnormality. Ordinary statistical analysis revealed that, although ejection fraction was lower in category (+) for proliferation of collagen fibers, ratio of end-systolic to volume index was reduced for category (+) of hypertrophy of myofibers. A significant correlation was present between hypertrophy of myofibers and proliferation of collagen fibers by Spearman rank correlation. When principal component analysis was applied to the hemodynamic data, two principal components could be extracted. Fisher's discriminant analysis could clearly differentiate two categories (-) and (+) in the semiquantitative histologic finding of proliferation of collagen fibers. The analysis indicated that contractility was reduced with elevated afterload in that category (+). Thus, proliferation of collagen fibers may play a pivotal role in deteriorating contractility in patients with dilated cardiomyopathy.

Evaluation of left ventricular contractility in hypertrophic cardiomyopathy from end-systolic pressure-volume relation

To evaluate myocardial contractility in hypertrophic cardiomyopathy (HC), we obtained the end-systolic pressure-volume relation (ESPVR) and the end-systolic stress-volume relation (ESSVR) by changing loading conditions with Angiotensin II. The left ventricular (LV) stress-shortening relation was also analyzed in order to assess myocardial contractility. LV end-systolic pressure, end-systolic volume, end-systolic stress, and ejection fraction were obtained at rest and during Angiotensin II infusion with simultaneous recordings of pressure and volume in 9 patients with hypertrophic cardiomyopathy and 9 normal subjects (N). The slopes of ESPVR, Emax, showed no significant difference (HC: 3.1 +/- 2.3 vs N: 2.6 +/- 1.4 mmHg/ml, ns). The slopes of ESSVR were statistically similar (HC: 5.2 +/- 2.1 vs N: 6.0 +/- 2.8 g/cm2 ml, ns). The slopes of end-systolic stress-ejection fraction relation were also in the same range in both groups (HC: -0.09 +/- 0.05 vs N: -0.10 +/- 0.05, ns). From these two different analyses of LV contractility, we conclude that myocardial contractility is normal in hypertrophic cardiomyopathy and not supernormal, at both chamber and muscle levels. Considering the increased muscle mass in hypertrophic cardiomyopathy (HC: 134 +/- 46 vs N: 74 +/- 19 g/m2, p less than 0.01), the presence of increased numbers of contractile units does not result in enhanced overall chamber contractility.

Phase-plane analysis of left ventricular chamber filling and midwall fiber lengthening in patients with left ventricular hypertrophy

Echocardiographic measurements of the left ventricle were used to define rates of circumferential fiber lengthening at the endocardium and midwall in 12 normal subjects and six patients with concentric left ventricular hypertrophy (wall thickness 11 to 16 mm). There was no difference in chamber size and systolic shortening in the two groups, but peak normalized lengthening rate [endocardial (+) VCF] was less than normal in the group with hypertrophy (4.8 +/- 1.4 and 3.1 +/- 0.9 sec-1, respectively, p less than .05). These results were contrasted with midwall (+) VCF data derived from two models that take into account nonuniform thickening across the left ventricular wall. Both models assume a constant left ventricular mass. The first allows changes in long axis and muscle cross-sectional area; the second assumes a constant cross-sectional area. Peak midwall (+) VCF with the first model was 2.1 +/- 0.5 sec-1 in the normal group and 1.4 +/- 0.3 sec-1 in the group with hypertrophy (p less than .01); with the second model peak midwall VCF was 2.8 +/- 0.6 and 1.4 +/- 0.4 sec-1 (p less than .01) in the two groups. The time to peak VCF and the dimension at the instant of peak (+) VCF were similar in the two groups. Phase-plane plots of length and velocity (dimension vs dD/dt) allow visual inspection and quantification of the relationships between instantaneous dimension, rate of change of dimension, and time in normal and hypertrophic hearts. These plots indicate abnormal filling of the left ventricular chamber and lengthening of midwall fibers in left ventricular hypertrophy.

Effects of intravenous injection of isosorbide dinitrate on the cardiovascular system

An assessment of the acute hemodynamic effect of intravenous isosorbide dinitrate (ISDN) was performed with a Mikro-tip angiocatheter in 10 patients during the diagnostic cardiac catheterization. Both left ventricular (LV) systolic pressure (SP) and end-diastolic pressure (EDP) were decreased by 2 mg of ISDN. Cardiac index, stroke work index and heart rate did not change significantly, and neither systemic vascular resistance nor pulmonary arteriolar resistance was reduced. Isovolumic phase and ejection phase indices of contractility were not altered. End-diastolic stress, an accurate index of preload, was reduced significantly (47.0 +/- 27.6 to 28.7 +/- 24.6 g/cm2, p less than 0.01), and mid-systolic stress, an index of afterload, was also reduced (371 +/- 102 to 332 +/- 85 g/cm2, p less than 0.05). No undesirable side effects were noted during this study. We concluded that bolus intravenous (IV) ISDN safely reduced both preload and afterload. As 2 mg of IV ISDN had no significant change on SVR, a larger dose of ISDN bolus injection might be needed for a significant arterial vasodilating effect. Bolus IV ISDN seems to be very effective in cases in which rapid reduction of LV filling pressure is mandatory.

Left ventricular chamber filling and midwall fiber lengthening in patients with left ventricular hypertrophy: overestimation of fiber velocities by conventional midwall measurements

Observations that the inner (subendocardial) half of the left ventricular wall contributes more to total left ventricular wall thickening than the outer (subepicardial) half may have important implications in the analysis of myocardial fiber length transients. Accordingly, we measured endocardial and midwall shortening and lengthening rates in normal and hypertrophic heart and compared the results obtained with conventional methods of measurement with those obtained with a modified model that does not depend on use of conventional assumptions about the midwall. This modified (two-shell) cylindrical model) method considers the substantial contribution of inner wall thickening and thus does not require the assumption of a theoretical midwall fiber that remains at the midwall throughout the cardiac cycle. Echocardiographic data from six normal subjects and six patients with concentric left ventricular hypertrophy (LVH) were examined; left ventricular wall thickness ranged from 8 to 10 mm in normal subjects and from 11 to 16 mm in the patients with LVH. By design, the standard measurements of left ventricular size (diastolic and systolic dimensions) and systolic function (fractional shortening and endocardial fiber shortening velocities) were equal in the two groups. Endocardial, conventional midwall, and modified midwall methods all indicate reduced fiber lengthening rates in patients with LVH; peak fiber lengthening rates for normal and LVH groups were 4.5 +/- 0.7 vs 3.1 +/- 0.8 sec-1 (p less than .02) at the endocardium, 2.3 +/- 0.4 vs 1.6 +/- 0.4 sec-1 (p less than .02) at the midwall (conventional method), and 2.1 +/- 0.3 vs 1.4 +/- 0.3 sec-1 (p less than .01) at the midwall (modified method).(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of compensation and decompensation in dilated cardiomyopathy

Left ventricular (LV) function was evaluated in 32 patients with dilated cardiomyopathy (DC) who underwent cardiac catheterization during the past 6 years (group 4), and the results were compared with the data of 30 normal subjects (group 1). The patients were divided into mildly (group 2, 12 patients) and severely symptomatic subgroups (group 3, 20 patients). DC was characterized by dilated and poorly contracting left ventricle with increased muscle mass, reduced cardiac output and elevated systemic vascular resistance. LV volume was larger, ejection fraction was lower, and end-diastolic and end-systolic stresses were higher in group 3 than in groups 1 and 2. No significant differences were seen in LV muscle mass and wall thickness between groups 2 and 3. A significant inverse correlation was seen between ejection fraction and end-systolic stress in patients with DC (Y = -0.05x + 48.7, r = 0.57, p less than 0.01). The slope of the correlation line between end-systolic stress and volume in DC (Y = 1.20x + 135, r = 0.52, p less than 0.02) was less steep than that of normal subjects (Y = 3.68x + 40, r = 0.64, p less than 0.001). These observations indicate that the primary problem of DC is depressed contractility.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential changes of left ventricular function after cineangiography in normal heart and coronary artery disease

To evaluate the effect of contrast material on left ventricular (LV) function, LV pressure and its first derivative were continuously monitored during and after LV cineangiography with Mikro-tip angiocatheters in 15 normal subjects (Group 1) and patients with coronary artery disease (CAD) without LV asynergy (Group 2, n = 10), with mild asynergy (Group 3, n = 12) and severe asynergy (Group 4, n = 13). In all 4 groups, systolic hypotension, decrease of negative dP/dt, and prolonged time constant of LV pressure fall (T) were observed in 30 seconds after dye injection, and all these parameters returned to the control value in 2 minutes. LV end-diastolic pressure (EDP) began to elevate at one minute, reached its peak at 2 minutes, and stayed elevated for 7 minutes. Although significant decrease in LV systolic pressure was seen, indexes of LV contractility, peak positive dP/dt and (dP/dt)/DP40, showed increase in all groups. No different directional changes of these parameters were observed among 4 groups. The degree of LVEDP elevation was parallel to the diastolic elastic stiffness constant (K) in Group 1 (r = 0.64, (p less than 0.05). It is concluded that systolic hypotension and prolonged relaxation are only transient, and elevation of LVEDP after the contrast material injection seems to be the effect of only acute volume overload.

Hypertrophic nonobstructive cardiomyopathy: a precise assessment of hemodynamic characteristics and clinical implications

A precise assessment of left ventricular function was performed in 20 patients with hypertrophic nonobstructive cardiomyopathy to elucidate the basic pathophysiology, and the data were compared with those in 22 normal subjects. Whereas end-diastolic pressure was high in those with cardiomyopathy, a more accurate index of preload, end-diastolic stress, did not differ from normal value. Afterload was about half the normal value. Both isovolumic indexes [peak positive dP/dt and (dP/dt)/DP40] and ejection phase indexes of contractility (ejection fraction) were in the normal range; however, the end-systolic stress volume ratio was significantly reduced (43% of the normal value). Although the left ventricular minute work index was in the normal range, the unit muscle performance (minute work/mass) was very low (49%). An abnormality of left ventricular relaxation was demonstrated by low peak negative dP/dt (56%) and prolonged time constant T (191%), and a stiff left ventricle was demonstrated by a high diastolic elastic stiffness constant (129%). These observations suggest that the contraction of a unit muscle is inappropriate to produce an adequate contraction of the whole ventricle, and that hypertrophy might be an adaptive process to maintain normal systolic function by increasing mass and reducing afterload.

[Pathophysiology of hypertrophic and congestive cardiomyopathies: a guide of fundamental therapeutic approach (author's transl)]

A precise assessment of left ventricular (LV) function was performed in 20 patients with hypertrophic cardiomyopathy (HCM) and 14 patients with congestive cardiomyopathy (CCM) to elucidate the pathophysiology of these diseases, expecting to establish a fundamental therapeutic approach of them. Twenty-two patients who underwent cardiac catheterization and were found to have normal LV function served as normal control. LV preload, defined as LV end-diastolic stress, was normal in HCM, and it was elevated in patients with CCM and congestive heart failure (CHF). While an index of afterload, defined as mid-systolic stress, was markedly reduced in HCM, it was elevated in CCM and CHF. Although three indices of LV contractility including the rate of LV pressure rise divided by developed pressure of 40 mmHg ((dp/dt)/DP40), ejection fraction (EF) and LV minute work index, were all in a normal range in HCM, they were very low in CCM. This observation indicates that the systolic function of HCM is normal as a pump, and that it is markedly reduced in CCM. One index of LV relaxation, which was the peak rate of LV pressure fall (peak negative dp/dt) was reduced in both HCM and CCM, and the other index, which was the time constant of LV pressure fall (the time constant T) was prolonged in both of these diseases. An index of compliance, defined as diastolic elastic stiffness constant (K) was high in HCM and normal in CCM, and the other index, defined as end-diastolic elastic stiffness was normal in HCM and high in patients with CCM and CHF. This observation suggests that chamber compliance is low in HCM, and that muscle compliance begins to decline with the appearance of CHF in CCM. Although poor systolic function is evident in CCM, poor contractility or inadequate contraction of a unit muscle is also suspected in HCM since 1) normal EF was maintained with very low afterload, 2) LV end-systolic volume index was normal with very low end-systolic stress, and 3) LV unit muscle minute work about one half of normal value with normal preload. Several important therapeutic guidelines can be derived from this study: As CCM is a disease of reduced LV contractility, the main therapy for this disease is to enhance the contractility. Elevation of preload and afterload are associated with the appearance of CHF, and this coincides with New York Heart Association functional class III. Therefore, the indication of preload and/or afterload reducing agents, such as diuretics and vasodilators, is considered for such patients. Although preload and/or afterload reducing agents are well known to be contraindicated in obstructive type of HCM, since they increase the intracardiac pressure gradient, these agents must be used with great precaution in nonobstructive type, as they reduce preload suddenly, and life-threatening low cardiac output might take place. For the same reason, strenuous exercise must be prohibited in HCM...