The pulse wave arrival time (QKd interval) in normal children

Korotkoff sounds dynamically reflect changes in cardiac function based on deep learning methods

Korotkoff sounds (K-sounds) have been around for over 100 years and are considered the gold standard for blood pressure (BP) measurement. K-sounds are also unique for the diagnosis and treatment of cardiovascular diseases; however, their efficacy is limited. The incidences of heart failure (HF) are increasing, which necessitate the development of a rapid and convenient pre-hospital screening method. In this review, we propose a deep learning (DL) method and the possibility of using K-methods to predict cardiac function changes for the detection of cardiac dysfunctions.

Influence of nifedipine coat-core and amlodipine on systemic arterial stiffness modulated by sympathetic and parasympathetic activity in hypertensive patients

The aim of this study was to compare the effects of nifedipine coat-core (once daily formulation) and amlodipine on systemic arterial stiffness in patients with hypertension. Study drugs were assigned by the randomized open-label crossover method. After the blood pressure was maintained below 130/85 mm Hg for 8 months by treatment with either drug in 48 hypertensive patients (aged 63.2+/-6.9 years; 64.5% men), they were switched to the other drug for another 8 months. The blood pressure, heart rate, plasma catecholamine level and brachial-ankle pulse wave velocity were measured before and after a bicycle ergometer testing. Heart rate recovery was calculated from the change of the heart rate after treadmill exercise testing. The high-frequency and low-frequency components of the heart rate variability spectrum were analyzed from 24-h Holter electrocardiograms. The change of blood pressure after exercise testing showed no significant difference between the two medications. However, the increases of heart rate, noradrenalin and branchial-ankle pulse wave velocity after exercise were significantly smaller with nifedipine treatment than with amlodipine (P=0.0472, P=0.006 and P=0.0472, respectively). Heart rate recovery was significantly faster with nifedipine treatment (P=0.0280). The nighttime high-frequency component of heart rate variability was significantly larger after nifedipine treatment than after amlodipine (P=0.0259), while the nighttime low/high-frequency ratio was significantly smaller with nifedipine (P=0.0429). Nifedipine reduced functional arterial stiffness and improved heart rate recovery by altering the autonomic activity balance in hypertensive patients.

Differences in arterial compliance among normotensive adolescent groups: Collins arterial compliance in adolescents

Decreased arterial compliance is an important predictor of cardiovascular risk. Pulse wave velocity correlates well with arterial compliance. Gender and ethnic differences in adult populations have been described. However, few data are available evaluating arterial compliance in adolescent subjects. Using a simple noninvasive oscillometric technique, brachial-ankle pulse wave velocity (baPWV) was measured as an index of arterial stiffness. Measurements were performed on a cross-sectional (65% African American, 52% female) sample of 205 normotensive (blood pressure <95% for gender, height, and age) adolescents with a mean age of 15.9 years (range, 12-21 years). The 205 adolescent subjects include 106 females and 99 males. In these adolescents, the mean baPWV was higher for males (1,096 cm/s) than for females (1,039 cm/s; p < 0.0024; 95% confidence interval [CI], 0.2051-0.9349), and for African Americans (1,080 cm/s) than for whites (1,040 cm/s; p < 0.0438; 95% CI, 0.0112-0.7888). Multiple regression analyses found a three-way interaction among gender, ethnicity, and age. The effect of age on baPWV was greater among African Americans (slope = 18.1 cm/s/year) and males (slope = 21.6) than among whites (slope = 11.0) and females (slope = 11.3), although these differences did not reach statistical significance. Differences in arterial compliance are already present and detectable in normotensive adolescent subjects. Decreased arterial compliance among adolescent groups correlates with the known adult risk for cardiovascular events among the same ethnic and gender groups.

Association of serum albumin and homocysteine levels and cardio-ankle vascular index in patients with continuous ambulatory peritoneal dialysis

BACKGROUND

The cardio-ankle vascular index (CAVI) is a newly developed arteriosclerotic measurement that has been proposed as an alternative to aortic pulse-wave velocity (PWV). The present study used the CAVI to identify the main factors associated with arteriosclerosis in continuous ambulatory peritoneal dialysis (CAPD) patients.

METHODS

Fifteen CAPD patients were enrolled in the study. The CAVI is independent of the pressure and vascular reflection between the heart valve and the ankle. Serum albumin, uric acid, total calcium, phosphorus, lipid levels, high-sensitivity C-reactive protein and homocysteine concentrations in CAPD patients were measured using standard methods. Total body fat mass, truncal and non-truncal fat mass and lean body mass were measured using dual energy X-ray absorptiometry with a Lunar DPX-L scanner.

RESULTS

CAPD patients had a mean CAVI of 9.37 +/- 3.16 m/sec, which was higher than the general population. The CAVI was negatively correlated with the serum albumin concentration (r=-0.548; p=0.034). Stepwise regression analysis showed that both the serum albumin concentration (beta=-0.643, p=0.013) and the serum homocysteine level (beta=0.486, p=0.004) were independently associated with the CAVI.

CONCLUSIONS

An increase in CAVI was independently associated with both serum albumin and homocysteine level.

Brachio-ankle pulse wave velocity and cardio-ankle vascular index (CAVI)

In order to diagnose arteriosclerosis in any part of the body, pulse wave velocity (PWV) measurement is a useful approach. However, it is considered that the technique of PWV measurement should be simplified. A new method for measuring PWV has therefore been proposed in Japan. The PWV of the brachial artery (ba) and the ankle was measured by applying air pressure with the aid of a volume plethysmograph. Comparisons between the baPWV measurement method and the conventional method are currently being performed. Since satisfactory results have been obtained to date, baPWV has gained popularity throughout Japan. Since this method measures PWV in the arm and foot, it may be said that aortic PWV is not reflected though a large amount of past PWV measurements. BaPWV is influenced by blood pressure. With the baPWV technique, blood pressure compensation is not carried out. Furthermore, the pulse pressure is measured by air pressure; therefore any stimulus that exerts pressure on an artery may influence these results. Due to these reasons, a cardie-ankle vascular index (CAVI) has been proposed in which the pressure wave form indicating the closing of the aortic valve appears in the form of an arterial pressure wave after a fixed delay time. This delay is the time difference between the actual closing of the aortic valve and the measuring point. Prior to the introduction of baPWV, PWV was measured in the carotid artery and foot. As in traditional PWV, baPWV uses the delay time, but between the brachial artery and the ankle artery. However, the carotid artery differs from the brachial artery, and the measured value differs depending on whether the arteriosclerosis is present in the carotid artery or the brachial artery. CAVI is calculated from the ECG, PCG, brachial artery waveform and ankle artery waveform using a special algorithm. This new method represents a breakthrough in the diagnosis of atherosclerosis.

Intra-aortic balloon pumping in acute mitral regurgitation reduces aortic impedance and regurgitant fraction

Acute mitral regurgitation (MR) is present in 10% of patients presenting with cardiogenic shock. To stabilize these patients, intra-aortic balloon pumping (IABP) is recommended, but the mechanism of IABP support in these patients is unknown. This animal study was designed to describe the hemodynamic effect of intra-aortic balloon pumping during cardiogenic shock induced by acute MR. In eight calves, left ventricular pressure-volume loops, aortic and left atrial pressure, and aortic, carotid artery, and coronary blood flow were recorded. Acute MR (range 36%-79%) was created by placing a metal cage in the mitral valve. Hemodynamic data was obtained at control, during acute MR, and during acute MR with 1:1 IABP support. Acute MR caused a decrease in cardiac output (-32%, P = 0.018), blood pressure, and carotid artery flow, whereas left ventricular output (+127%, P = 0.018), end-diastolic volume, and left atrial pressure all significantly increased. Stroke work, ejection fraction, and coronary blood flow were not significantly changed, and no signs of ischemia were seen on the ECG. The IABP raised average cardiac output by 31% (P = 0.012) and significantly raised blood pressure and flow to the brain while decreasing systemic vascular resistance. Left ventricular function and mean coronary blood flow did not change, but diastolic coronary flow became more important as shown by the increase in diastolic fraction from 64% to 95%. (P = 0.028). Average MR dropped by 7.5% (P = 0.025). In conclusion, application of the IABP during acute MR lowers aortic impedance, resulting in less MR and more output toward the aorta without changing left ventricular function.

Ambulatory measurement of the QKD interval normalized to heart rate and systolic blood pressure to assess arterial distensibility--value of QKD(100-60)

BACKGROUND

Reduced distensibility of large arteries plays an important role in cardiovascular risk. Determination of the QKD interval during the ambulatory measurement of blood pressure enables calculation of an index of arterial distensibility. This index, the QKD(100-60), is the theoretical value of QKD at systolic blood pressure of 100mmHg and heart rate of 60bpm obtained from the linear bivariate relationship linking QKD, systolic blood pressure and heart rate on a hundred successive values measured over 24h. This study was designed to examine the relationship between QKD and QKD(100-60) on heart rate and systolic function of the left ventricle, the two parameters governing the pre-ejection time which is part of the QKD interval.

METHODS AND RESULTS

In a population of 203 untreated hypertensive patients having benefited from an ambulatory measurement of blood pressure over 24h with QKD monitoring and an M-mode echocardiographic recording of the left ventricle, we found that although mean QKD was linked to heart rate and systolic function of the left ventricle, QKD(100-60) was not. It fell significantly with age, and to a greater extent in the sustained hypertensives than in white-coat hypertensives.

CONCLUSION

QKD(100-60) constitutes an index of arterial distensibility independent of the pre-ejection time. As an adjunct to the ambulatory measurement of blood pressure, its determination is simple and completely automatic, thus eliminating observer bias.

Extended Willis circle model to explain clinical observations in periorbital arterial flow

A fluid-dynamic model of the circle of Willis and its periorbital links with the external carotid arteries has been established and tested. It is based on anatomic data and takes Doppler measurements as flow input conditions. The model explains, on fluid-dynamic grounds, the clinical observations of periorbital reverse flow and arrival pulse time delay. It also obtains the velocity and pressure pulse at any point of the studied area. This allows the comparison between the normal or healthy condition and the flow distribution when an internal carotid is externally or pathologically occluded. Several combinations of the communicating artery sizes are explored to obtain the reduced cerebral flow. The combination of the communicating diameters can lead to insufficient irrigation which can be hydrodynamically assessed. No other physiological response is included, and the results must be considered as a minimum assured. These results show the need for a common evaluation of the alternative paths and explain some paradoxes found in literature.

A base mutation of the C-erbA beta thyroid hormone receptor in a kindred with generalized thyroid hormone resistance. Molecular heterogeneity in two other kindreds

Generalized thyroid hormone resistance (GTHR) is a disorder of thyroid hormone action that we have previously shown to be tightly linked to one of the two thyroid hormone receptor genes, c-erbA beta, in a single kindred, A. We now show that in two other kindreds, B and D, with differing phenotypes, there is also linkage between c-erbA beta and GTHR. The combined maximum logarithm of the odds score for all three kindreds at a recombination fraction of 0 was 5.77. In vivo studies had shown a triiodothyronine (T3)-binding affinity abnormality in nuclear receptors of kindred A, and we therefore investigated the defect in c-erbA beta in this kindred by sequencing a major portion of the T3-binding domain in the 3'-region of fibroblast c-erbA beta cDNA and leukocyte c-erbA beta genomic DNA. A base substitution, cytosine to adenine, was found at cDNA position 1643 which altered the proline codon at position 448 to a histidine. By allelic-specific hybridization, this base substitution was found in only one allele of seven affected members, and not found in 10 unaffected members of kindred A, as expected for a dominant disease. Also, this altered base was not found in kindreds B or D, or in 92 random c-erbA beta alleles. These results and the fact that the mutation is predicted to alter the secondary structure of the crucial T3-binding domain of the c-erbA beta receptor suggest this mutation is an excellent candidate for the genetic cause of GTHR in kindred A. Different mutations in the c-erbA beta gene are likely responsible for the variant phenotypes of thyroid hormone resistance in kindreds B and D.

Familial generalized resistance to thyroid hormones: report of three kindreds and correlation of patterns of affected tissues with the binding of [125I] triiodothyronine to fibroblast nuclei

We here report three kindreds with a total of 19 persons affected with central and peripheral resistance to thyroid hormones: one kindred with 10 affected persons is the largest reported to date. Male to male transmission of the syndrome was evident in two kindreds, consistent with an autosomal dominant mode of inheritance. During several years of follow up, the degree of resistance to thyroid hormones did not ameliorate. Within a given kindred, a given tissue or tissues was consistently more resistant to thyroid hormone than other tissues. The pattern of tissues most affected in one kindred differed from that of another kindred, perhaps reflecting the inherited underlying molecular defects. Members of kindred A frequently had bone involvement, and several had learning disabilities and recurring infections, while most members of kindreds B and C had little bone involvement, but marked hepatic and cardiac resistance to thyroid hormones. Kinetic studies of the binding of [125I] triiodo-L-thyronine to nuclei from skin fibroblasts from affected patients from each of the kindreds demonstrated decreased maximum binding as compared to normal fibroblasts, but there was no correlation between this parameter and other features of the disease. Four of the 19 patients had previously been treated inappropriately with antithyroid therapies, demonstrating how the syndrome may be readily confused with Graves' disease by some clinicians. Behavior or school performance improved in all children treated with thyroid hormones, and a growth spurt was documented in six children, but objective improvement in IQ scores was not demonstrated, suggesting that initiation of hormone therapy at an early age may be important for maximum benefit.

Effects of aging on changing arterial compliance and left ventricular load in a northern Chinese urban community

Pulse wave velocity (PWV) was measured by means of transcutaneous Doppler techniques in the aorta, right arm, and right leg of 480 normal subjects of both sexes in urban Beijing, China (age range 3 to 89 years, mean age 41 +/- 20.8 SD); supine blood pressure was recorded in the brachial artery of each subject with standard sphygmomanometric procedures. Serum cholesterol was determined in a subgroup of 79 subjects (age 17 to 85 years, mean 47 +/- 26 SD). PWV (y in cm/sec) was found to vary with age (x, years) at each of the three locations according to the following regression equations: aorta, y = 9.2x + 615, r = .673 (p less than .001); right arm, y = 4.8x + 998, r = .453 (p less than .001); right leg, y = 5.6x + 791, r = .630 (p less than .001). Systolic, diastolic, mean, and pulse pressures were found to increase with age. PWV also increased with mean supine blood pressure but was not related to serum cholesterol (average 4.49 +/- 0.11 [SEM], mmol/l). Compared with that of Western populations, serum cholesterol tended to be lower at all age groups, systolic pressure higher at ages over 35 years, and PWV higher at all ages. Because change in PWV is directly related to change in arterial compliance, these results indicate that aging and not concomitant atherosclerosis (known to be rare in Asian populations) is the dominant factor associated with reduced arterial compliance and increased left ventricular load in these subjects.

Euthyroid familial hyperthyroxinemia due to abnormal thyroid hormone-binding protein

A family is described in which three members had an elevated total serum thyroxine level and free thyroxine index. Each affected subject was clinically euthyroid and had a normal pulse wave arrival time (QKd), serum triiodothyronine and free thyroxine levels, and a normal serum thyroxine-binding globulin (TBG) concentration. Electrophoresis of their serum with 125I-labeled thyroxine revealed increased thyroxine binding in the albumin region. In addition, this abnormal protein, like thyroxine-binding globulin, bound 125I-labeled triiodothyronine and 125I-labeled reverse triiodothyronine. However, electrophoresis of serum treated by sialidase (neuraminidase) digestion suggested that this abnormal protein is not an anomalous form of thyroxine-binding globulin "buried" in the albumin area. These cases of euthyroid familial hyperthyroxinemia due to an abnormal thyroid hormone-binding protein show that an elevated serum thyroxine level or free thyroxine index is not always sufficient to confirm the presence of thyrotoxicosis.