Biomedical subjects

Pierre Abraham

Publications and source records attributed to Pierre Abraham.

At least 19 recordsLinked to original sources

PubMed2006

Estimation of the functional role of arterial pathways to the buttock circulation during treadmill walking in patients with claudication.

The aim of the study was to estimate the functional contribution of the arterial inflow pathways to the pelvic circulation during walking in patients with stage 2 lower extremity arterial disease. Transcutaneous oxygen pressure (Ptc(O(2))) changes during exercise can be used to estimate the severity of regional blood flow impairment while walking. Seventy patients with stable lower limb claudication were studied using a multivariate linear regression model. The relationship between exercise-induced buttock Ptc(O(2)) changes, the ipsilateral calf Ptc(O(2)) changes, and the arterial diameters of the pelvic arteriographic pathways were analyzed. The ipsilateral hypogastric and lumbar pathway, as well as the ipsilateral calf Ptc(O(2)) changes, were the only variables significantly related to buttock Ptc(O(2)) changes (r = 0.47; P < 0.001). Their normalized respective contribution to the regressive model was 39%, 19%, and 18%. None of the contralateral hypogastric, mesenteric, and sacral pathways or pathways stemming from the external iliac artery showed significant correlation to buttock Ptc(O(2)) changes. The ipsilateral hypogastric and ipsilateral lumbar pathways are the major pathways responsible for the functional buttock blood flow supply during walking. The role of contralateral hypogastric, inferior mesenteric, and median sacral pathways and arteries distal to the internal iliac trunk is negligible in the normal or compensatory blood flow supply. Distal Ptc(O(2)) decrease at exercise aggravates proximal Ptc(O(2)) decrease, possibly through the occurrence of a "steal phenomenon" of distal over proximal circulation during walking.

Aged↗

PubMed2006

S-transform applied to laser Doppler flowmetry reactive hyperemia signals.

Laser Doppler flowmetry signals give information about many physiological activities of the cardiovascular system. The activities manifest themselves in rhythmic cycles. In order to explore these activities during the reactive hyperemia phenomenon, a novel time-frequency method, called the S-transform, based on a scalable Gaussian wavelet, is applied. The goal is to have a deeper understanding of reactive hyperemia. This paper focuses on the evaluation of the different activities between a rest signal and an hyperemia signal, both acquired simultaneously on the two forearms of healthy subjects. The results show that after the release of the occlusion, the myogenic, neurogenic, and endothelial related activities clearly increase on the forearm where the occlusion took place. Then, they return progressively to their basal level. However, on the rest forearm, no increase is noted for the three activities. The mechanisms that take place during reactive hyperemia are, therefore, local. The S-transform proves to be a suited time-frequency method, in order to analyze laser Doppler signal underlying mechanisms.

Adult↗

PubMed2006

Simultaneous arterial pressure recordings improve the detection of endofibrosis.

PURPOSE: Exercise improves the diagnostic performance of ankle-to-brachial index (ABI) in the detection of exercise-induced arterial endofibrosis (EIAE). Pressure values for all four limbs are required to calculate ABI, but rapid systemic pressure changes occur during the recovery period from exercise. We checked whether after exercise, ABI calculated from simultaneous measurements was better than from consecutive measurements for differentiating athletes with EIAE from normal athletes. METHODS: We studied 42 normal athletes and 42 athletes suffering from unilateral pain caused by histologically proven EIAE. Bilateral brachial and ankle (ASBP) systolic blood pressure levels were simultaneously measured in the supine position at rest and every minute during the first 4 min of the recovery from incremental maximal exercise. Using receiver operating characteristics curves (ROC), we compared the diagnostic performance of single-leg ASBP and ABI values and between-leg ASBP (DeltaASBP) and ABI (DeltaABI) differences, calculated from simultaneous (simu) versus consecutive (cons) measurements, to discriminate athletes with EIAE from normal athletes. RESULTS: For single-leg postexercise values, ROC curve area was significantly higher for ABIsimu compared with ASBPsimu (P < 0.05, r = 0.91) and ASBPrand (P < 0.05, r = 0.68). Areas (+/- SE of area) of the ROC curves for postexercise Delta ASBPsimu and Delta ABIsimu were 0.97 +/- 0.01 and 0.97 +/- 0.02, respectively, and were higher than areas for postexercise Delta ASBP and Delta ABI calculated from consecutive and random measurements (P < 0.01). Accuracy for postexercise Delta ASBPsimu and Delta ABIsimu in discriminating EIAE from normal athletes was 93% [95% CI; 85-97], with a cutoff point of 22 mm Hg and 0.10, respectively. CONCLUSION: Delta ASBP and/or Delta ABI calculated from simultaneous pressure measurements should be recommended when searching for unilateral EIAE. Whether this result is applicable in the detection of early atherosclerotic lesions in sedentary subjects requires future investigation.

Adult↗

PubMed2006

Aldose reductase pathway inhibition improved vascular and C-fiber functions, allowing for pressure-induced vasodilation restoration during severe diabetic neuropathy.

Pressure-induced vasodilation, a neurovascular mechanism relying on the interaction between mechanosensitive C-fibers and vessels, allows skin blood flow to increase in response to locally nonnociceptive applied pressure that in turn may protect against pressure ulcers. We expected that severe neuropathy would dramatically affect pressure-induced vasodilation in diabetic mice, and we aimed to determine whether pressure-induced vasodilation alteration could be reversed in 8-week diabetic mice. Control and diabetic mice received no treatment or sorbinil, an aldose reductase inhibitor, or alagebrium, an advanced glycation end product breaker, the last 2 weeks of diabetes. Laser Doppler flowmetry was used to evaluate pressure-induced vasodilation and endothelium-dependent vasodilation after iontophoretic delivery of acetylcholine (ACh). We assessed the nervous function with measurements of motor nerve conduction velocity (MNCV) as well as the C-fiber-mediated nociception threshold. Pressure-induced vasodilation, endothelial response, C-fiber threshold, and MNCV were all altered in 8-week diabetic mice. None of the treatments had a significant effect on MNCV. Although sorbinil and alagebrium both restored ACh-dependent vasodilation, sorbinil was the sole treatment to restore the C-fiber threshold as well as pressure-induced vasodilation development. Therefore, the inhibition of aldose reductase pathway by sorbinil improved vascular and C-fiber functions that allow pressure-induced vasodilation restoration that could limit neuropathic diabetic cutaneous pressure ulcers.

Acetylcholine↗

PubMed2005

The physiological response of ankle systolic blood pressure and ankle to brachial index after maximal exercise in athletes is dependent on age.

The development of sports activities in the over forties has increased the number of middle-aged patients performing heavy-load exercise. The normal response of ankle systolic blood pressure (ASBP) and ankle to brachial index (ABI) to intense exercise is known in young athletes, but little is known for other age groups. Three groups of 21 athletes: <20 (G1), 20-40 (G2), and >40 (G3) years old, respectively, were studied. ASBP and brachial systolic blood pressure (BSBP) were measured simultaneously before and after an incremental maximal cycle ergometer test. Rest ABI was higher in G3 compared to G1 (P<0.001: ANOVA, Bonferroni). Compared to respective resting values, BSBP, at 1 min of recovery, was increased for the three groups of age (P<0.001) whereas ASBP was unchanged for G1 and G2, and significantly increased for G3 (P<0.001). ASBP was significantly higher in G3 than in G1 and G2, ABI was lower in G1 and G2 compared to G3: 0.70+/-0.11, 0.76+/-0.09 and 0.91+/-0.14, respectively. This age-related ABI increase is consistent with the impaired vasodilator capacity observed in aging normal subjects but not with the decrease observed in ABI resting values in epidemiological studies. ABI is higher in older than in younger athletes at rest and after exercise. In aging athletes, aiming to detect mild to moderate arterial lesions, it is likely that normal limits defined in young athletes are not valid.

Adolescent↗

PubMed2005

Comparison between Hilbert-Huang transform and scalogram methods on non-stationary biomedical signals: application to laser Doppler flowmetry recordings.

A significant transient increase in laser Doppler flowmetry (LDF) signals is observed in response to a local and progressive cutaneous pressure application on healthy subjects. This reflex may be impaired in diabetic patients. The work presents a comparison between two signal processing methods that provide a clarification of this phenomenon. Analyses by the scalogram and the Hilbert-Huang transform (HHT) of LDF signals recorded at rest and during a local and progressive cutaneous pressure application are performed on healthy and type 1 diabetic subjects. Three frequency bands, corresponding to myogenic, neurogenic and endothelial related metabolic activities, are studied at different time intervals in order to take into account the dynamics of the phenomenon. The results show that both the scalogram and the HHT methods lead to the same conclusions concerning the comparisons of the myogenic, neurogenic and endothelial related metabolic activities-during the progressive pressure and at rest-in healthy and diabetic subjects. However, the HHT shows more details that may be obscured by the scalogram. Indeed, the non-locally adaptative limitations of the scalogram can remove some definition from the data. These results may improve knowledge on the above-mentioned reflex as well as on non-stationary biomedical signal processing methods.

Algorithms↗

PubMed2005

Lyapunov exponents of laser Doppler flowmetry signals in healthy and type 1 diabetic subjects.

The skin of diabetic subjects presents abnormalities in capillary blood flow and its regulation, often leading to the generation of plantar ulcers. In order to gain insight into this pathology for type 1 diabetic patients, Lyapunov exponents (LEs) of signals reflecting microvascular perfusion--laser Doppler flowmetry (LDF) signals--are calculated. The algorithm to compute LEs is first validated on simulated data and LDF surrogates. Then, LDF signals recorded at rest and during the application of local and progressive pressure of 11.1 Pa/s are processed. The exponents appear in pairs and are different for healthy and type 1 diabetic subjects at rest; P = 0.0556 for the 7th, 8th, and 9th LEs. Furthermore, progressive pressure has also a distinct effect on LEs. The difference is more pronounced for diabetic patients, for whom P = 0.0625 for the four LEs of highest absolute value. Because these differences arise from abnormalities in microvascular blood flow, they may help to explain the high prevalence of type 1 diabetic patients developing foot ulcers.

Animals↗

PubMed2005

Near-infrared spectroscopy and transcutaneous oxygen pressure during exercise to detect arterial ischemia at the buttock level: comparison with arteriography.

BACKGROUND: Noninvasive tests are required to detect (in both male and female subjects and side by side) arteries toward the hypogastric circulation that are likely to present significant lesions as a cause of buttock claudication. METHODS: We compared the accuracy of near-infrared spectroscopy (NIRS) and transcutaneous oxygen pressure (TCP o 2 ) on both buttocks during walking tests to detect lesions on the arteries toward the hypogastric circulation. NIRS was considered abnormal if recovery time to pre-exercise values was greater than 240 seconds for tissue oxygen saturation (absent data being coded 0), and TCP o 2 was coded abnormal if the minimal value of buttock changes minus chest changes was lower than -15 mm Hg. The study was conducted in a university hospital; there were 30 ambulatory patients with stage 2 claudication of the Fontaine classification. RESULTS: Angiography showed 36 abnormal (stenosis > 75%) and 24 normal arterial axes toward the buttocks circulation. NIRS and TCP o 2 provided respectively 55% (range, 41.6% to 67.9%) and 82% (range, 69.6% to 90.5%) accuracy (95% confidence interval) to predict the presence of arteriographically proven lesions; P < .05. CONCLUSIONS: Using available cut-off points proposed in the literature, NIRS showed a lower diagnostic accuracy than TCP o 2 for the prediction of lesions on the arterial tree to the hypogastric circulation. NIRS is a recent technique as compared with TCP o 2 , and its diagnostic accuracy might improve in the future. Currently, one should carefully weigh the advantages and limits of NIRS and TCP o 2 when a choice is to be made between them to monitor exercise-induced changes resulting from lower limb arterial disease at the proximal level.

Aged↗

PubMed2004

Early vasodilator response to anodal current application in human is not impaired by cyclooxygenase-2 blockade.

It is generally acknowledged that cutaneous vasodilatation in response to monopolar galvanic current application would result from an axon reflex in primary afferent fibers and the neurogenic inflammation resulting from neuropeptide release. Previous studies suggested participation of prostaglandin (PG) in anodal current-induced cutaneous vasodilatation. Thus the inducible cyclooxygenase (COX) isoform (COX-2), assumed to play a key role in inflammation, should be involved in the synthesis of the PG that is released. Skin blood flow (SkBF) variations induced by 5 min of 0.1-mA monopolar anodal current application were evaluated with laser-Doppler flowmetry on the forearm of healthy volunteers treated with indomethacin (COX-1 and COX-2 inhibitor), celecoxib (COX-2 inhibitor), or placebo. SkBF was indexed as cutaneous vascular conductance (CVC), expressed as percentage of heat-induced maximal CVC (%MVC). Urinalyses were performed to test celecoxib treatment efficiency. No difference was found in CVC values at rest: 14.3 +/- 4.0, 11.9 +/- 3.2, and 10.9 +/- 2.0% MVC after indomethacin, celecoxib, and placebo treatment, respectively. At 10 min after the onset of anodal current application, CVC values were 22.2 +/- 4.9% MVC (not significantly different from rest) with indomethacin, 85.7 +/- 15.3% MVC (P < 0.001 vs. rest) with celecoxib, and 70.4 +/- 13.1% MVC (P < 0.001 vs. rest) with placebo. Celecoxib significantly depressed the urinary prostacyclin metabolite 6-keto-PGF(1alpha) (P < 0.05 vs. placebo). Indomethacin, but not celecoxib, significantly inhibited the anodal current-induced vasodilatation. Thus, although they are assumed to result from an axon reflex in primary afferent fibers and neurogenic inflammation, these results suggest that the early anodal current-induced vasodilatation is mainly dependent on COX-1-induced PG synthesis.

Adult↗

PubMed2004

Spectral components of laser Doppler flowmetry signals recorded in healthy and type 1 diabetic subjects at rest and during a local and progressive cutaneous pressure application: scalogram analyses.

A significant transient increase in laser Doppler flowmetry (LDF) signals is observed in response to a local and progressive cutaneous pressure application in healthy subjects. This reflex may be impaired in diabetic patients. The work presents a signal processing providing the clarification of this phenomenon. Scalogram analyses of LDF signals recorded at rest and during a local and progressive cutaneous pressure application are performed on healthy and type 1 diabetic subjects. Three frequency bands, corresponding to myogenic, neurogenic and endothelial related metabolic activities, are studied. The results show that, at rest, the scalogram energy of each frequency band is significantly lower for diabetic patients than for healthy subjects, but the scalogram relative energies do not show any statistical difference between the two groups. Moreover, the neurogenic and endothelial related metabolic activities are significantly higher during the progressive pressure than at rest, in healthy and diabetic subjects. However, the relative contribution of the endothelial related metabolic activity is significantly higher during the progressive pressure than at rest, in the interval 200-400 s following the beginning of the pressure application, but only for healthy subjects. These results may improve knowledge on cutaneous microvascular responses to injuries or local pressures initiating diabetic complications.

Adult↗

PubMed2004

Time-frequency analysis of laser Doppler flowmetry signals recorded in response to a progressive pressure applied locally on anaesthetized healthy rats.

The laser Doppler flowmetry technique has recently been used to report a significant transient increase of the cutaneous blood flow signal, in response to a local non-noxious pressure applied progressively on the skin of both healthy humans and rats. This phenomenon is not entirely understood yet. In the present work, a time-frequency analysis is applied to signals recorded on anaesthetized healthy rats, at rest and during a cutaneous pressure-induced vasodilation (PIV). The comparison, at rest and during PIV, of the scalogram relative energies and scalogram relative amplitudes in five bands, corresponding to five characteristic frequencies, shows an increased contribution for the endothelial related metabolic activity in PIV signals, till 400 s after the beginning of the progressive pressure application. The other subsystems (heart, respiration, myogenic and neurogenic activities) contribute relatively less during PIV than at rest. The differences are statistically significant for all the relative activities in the interval 0-200 s following the beginning of the pressure. These results and others obtained on patients, such as diabetics, could increase the understanding of some cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers.

Anesthetics, Local↗

PubMed2004

Low skin temperature impairs the cutaneous vasodilator response to local progressive pressure strain.

A pressure-induced vasodilation (PIV) was recently reported as a putative protective response in human skin. Therefore, we examined the influence of skin temperatures on cutaneous blood flow responses to local progressive pressure strain. Ten healthy volunteers were studied at different ambient temperatures leading to low (29.0 +/- 0.3 degrees C), intermediate (32.6 +/- 0.1 degrees C), high (33.9 +/- 0.1 degrees C) and very high (36.0 +/- 0.1 degrees C) skin temperatures. We measured cutaneous blood flow using laser Doppler flowmetry on the foot in response to a local progressive pressure increase of 5.0 mm Hg min(-1). Progressive pressure strain led to an almost linear cutaneous laser Doppler flow decrease at both low and intermediate skin temperatures (-40.1 +/- 6.6% and -31.2 +/- 6.5% from baseline at 30 +/- 1.25 mm Hg), whereas at both high and very high skin temperatures, subjects responded with a transient cutaneous vasodilation (+33.6 +/- 10.6% and +50.6 +/- 15.4% from baseline at 30 +/- 1.25 mm Hg). These findings suggest that high skin temperatures are required for the PIV to develop.

Acclimatization↗

PubMed2004

Pain description in patients with isolated proximal (without distal) exercise-related lower limb arterial ischemia.

Among the last 250 claudicants referred to the laboratory for transcutaneous oxygen pressure recording at exercise, we analyzed the symptoms reported by the 36 patients who showed isolated proximal (without distal) ischemia. Among the symptomatic proximal sites cited by these patients, the hip and thigh represent 60%, whereas the buttock is cited in fewer than 25% of cases. Buttock symptoms are reported in only 31% of symptomatic patients. 'Buttock' claudication is probably not the dominant symptom in isolated proximal vascular ischemia. Assessing proximal lower limb ischemia through the sole detection of 'buttock pain' could contribute to the underestimation of proximal vascular ischemia.

Aged↗

PubMed2004

Past, present and future of arterial endofibrosis in athletes: a point of view.

Exercise-induced arterial endofibrosis (EIAE) is now a 20-year-old concept. Initially observed in highly trained cyclists, it has been found in many other male and female endurance athletes. Most stenoses are located on the first centimetres of the external iliac artery but other localisation may be found. The disease is defined by specific histological findings showing fibrosis of the intimal and medial wall of the artery. Ankle pressure measurement plays a key role in the diagnosis of EIAE provided that the exercise tests reproduce symptoms and are performed with the subject being highly trained, and that pressure measurements are performed early following exercise. Various cut-off values have been proposed in the literature. Magnetic resonance imaging or arteriography or ultrasound imaging should be performed by trained operators only. Surgical 'endofibrosectomy' is preferable in young cyclists generally associated with a saphenous enlargement patch. We do not recommend angioplasty. Athletes are generally allowed to return to competition within 3-4 months following surgery. Many unanswered questions remain, specifically about the pathophysiology of this disease. Mechanical and pressure strain play a central role in the development of EIEA, but nutritional and haemorrheological factors, hormonal changes and a genetic predisposition are likely to contribute. New techniques could facilitate the diagnosis of EIAE.

Angiography↗

PubMed2004

Impaired pressure-induced vasodilation at the foot in young adults with type 1 diabetes.

Vascular and neurological mechanisms are both likely to be involved in foot ulcer. We recently reported a pressure-induced vasodilation (PIV), relying on unmyelinated afferent excitation. We previously found that cutaneous blood flow in response to locally applied pressure might be impaired in diabetic patients because of the combined effects of low cutaneous temperature and alterations in microcirculatory function. Therefore, we aimed to analyze whether, at a relatively high cutaneous temperature, PIV is present in type 1 diabetes and to assess endothelial-dependent vasodilation and endothelium-independent vasodilation. We measured cutaneous blood flow using laser Doppler flowmetry on the head of the first metatarsus in response to applied pressure at 5.0 mmHg/min in warm conditions (29.5 +/- 0.2 degrees C). Responses to iontophoresis of acetylcholine (endothelium dependent) and sodium nitroprusside (endothelium independent) were measured using laser Doppler flowmetry in the forearm. The data indicate that PIV exists at the foot level in normal subjects, whereas it was not found in diabetic patients. In diabetic patients, the nonendothelial-mediated response to sodium nitroprusside was preserved, whereas the endothelial-mediated response to acetylcholine was impaired. These findings might be relevant to the high prevalence of foot ulcer that occurs in diabetic patients.

Adult↗

PubMed2004

Early endothelial dysfunction severely impairs skin blood flow response to local pressure application in streptozotocin-induced diabetic mice.

Pressure-induced vasodilation (PIV) is a mechanism whereby skin blood flow increases in response to progressive locally applied pressure. Skin blood flow in response to applied pressure decreased early in diabetic patients as a result of vascular and/or neural impairment. This study was designed to determine the effect of vascular changes on PIV in 1-week streptozotocin-induced diabetic mice. We assessed cutaneous microvascular response to local increasing pressure application measured by laser Doppler flowmetry (LDF) and endothelium-dependent and -independent vasodilation by iontophoretic delivery of acetylcholine and sodium nitroprusside and sciatic motor nerve conduction velocity and morphometry. In control mice, LDF increased 34% from baseline to 0.2 kPa external pressure, showing PIV response. In contrast, diabetic mice had no LDF increase in response to progressive external pressure. Moreover, after iontophoretic delivery of acetylcholine, endothelium-dependent vasodilation was largely attenuated in diabetic mice (25%) compared with control mice (81%), whereas vasodilation to sodium nitroprusside was not different between groups. Nerve function as assessed by sciatic nerve conduction velocity and morphometry did not differ between groups. These findings suggest that endothelial impairment is sufficient to severely alter PIV response, which seems to be highly sensitive to endothelial nitric oxide levels. PIV suppression could favor diabetes complications such as diabetic foot ulcers.

Animals↗

PubMed2003

Transcutaneous oxygen pressure measurements on the buttocks during exercise to detect proximal arterial ischemia: comparison with arteriography.

BACKGROUND: We sought to identify whether transcutaneous oxygen tension (tcPo2) measurements could be used to noninvasively detect lesions in the arterial network supplying blood flow to the hypogastric circulation. METHODS AND RESULTS: A study was undertaken in vascular patients with suspected (PC, n=43) and not with suspected (NPC, n=34) proximal ischemia. TcPo2 was measured on both buttocks and with a chest reference electrode. Arteriography on the right or left side was positive for stenoses (> or =75%) or occlusion of one or more of the following arteries: the aorta, the common iliac arteries, or the internal iliac arteries. The arteriography was compared with the resting tcPo2 values (REST) and with the minimal value (MIN) and maximal change from rest normalized to eventual chest changes (DROP) recorded during or after a treadmill test. REST, MIN, and DROP were, respectively, as follows in positive versus negative arteriograms (mean+/-SD; in mm Hg): 80.2+/-10.9 versus 78.6+/-11.5 (P>0.05), 55.2+/-20.0 versus 69.9+/-15.8 (P<0.001), and -31.8+/-17.6 versus -9.5+/-6.4 (P<0.0001) in PC and 78.9+/-14.0 versus 80.5+/-14.3 (P>0.05), 64.4+/-21.0 versus 75.1+/-14.6 (P<0.02), and -24.1+/-13.5 versus -8.7+/-4.8 (P<0.0001) in NPC. In PC and NPC respectively, with a cutoff point of -16 and -15 mm Hg, DROP showed, respectively, 83%/82% and 79%/86% sensitivity/specificity in the diagnosis of positive arteriograms. CONCLUSIONS: Proximal ischemia is a frequent finding in vascular patients. TcPo2 measurement on the buttocks during exercise is a sensitive and specific indicator for lesions in the arterial tree toward the hypogastric circulation. Potentially it could objectively assess the response to endovascular or surgical approaches to iliac lesions.

Angiography↗

PubMed2002

Holter changes resulting from right-sided and bilateral infrastellate upper thoracic sympathectomy.

BACKGROUND: We tested the hypothesis that no right-sided dominance exists after infrastellate surgical upper-thoracic sympathectomy. We aimed to confirm whether a significant bradycardia was constant and only dependent on the right side. METHODS: We performed 24-hour Holter electrocardiographic recordings in 12 patients referred for bilateral sympathectomy. Surgery was performed at two distinct times allowing for the study of the consequences of unilateral right and bilateral sympathectomy. RESULTS: Heart rate was 77 +/- 8 beats per minute before surgery on the 24-hour recording and significantly decreased after bilateral (67.8 +/- 6.5 beats per minute; p < 0.05) but not after unilateral right sympathectomy. Consistently spectral analysis variables significantly changed after bilateral surgery but showed no right-sided dominance. Little effect of sympathectomy was found on the QT interval, which tended to decrease after bilateral sympathectomy. CONCLUSIONS: Patients should be informed of the bradycardia resulting from sympathectomy. No right-sided dominance can be found consistently with the random distribution of substellate cardiac fibers reported in anatomic studies.

Adult↗