Latissimus dorsi breast reconstruction with or without implants: A comparison between outcome and patient satisfaction.

BACKGROUND: The latissimus dorsi (LD) flap is largely used in breast reconstruction. The aim of this study is to evaluate and compare the advantage of the LD flap in association with an implant to that of LD flap in association with lipofilling to add additional volume following breast reconstruction by assessing the number of revision procedures, length of hospitalization, complication rate, and patient satisfaction. METHODS: A retrospective cohort study was performed to evaluate complication rate, number and type of revision procedures required, hospitalization time, and overall duration of the reconstructive process in patients undergoing LD breast reconstruction in our department between January 2012 and March 2015. Patient satisfaction was assessed using BREAST-Q®. RESULTS: Ninety-five breast reconstructions performed on 90 patients were included. In 38 patients, 42 breasts were reconstructed using LD flap in association with lipofilling (Group 1). In the remaining 52 patients, 53 breast reconstructions were performed using LD flap in association with an implant (Group 2). Findings concerning total hospitalization time, overall duration of the reconstructive process, and the distribution of supplementary surgical procedures demonstrated no statistically significant differences between the two groups. However, the surgical complication rate was higher in Group 2 than in Group 1 (14.2% vs. 18.8%, respectively). Regarding BREAST-Q, a detailed analysis of the "satisfaction with breasts" domain showed a higher score for Group 1 than for Group 2. CONCLUSIONS: The association of a breast implant with LD reconstruction does not decrease breast reconstruction time in terms of the number of revision procedures and hospitalization time, exposes patients to a higher complication rate, and does not improve patient satisfaction.

Postoperative complications of male to female sex reassignment surgery: A 10-year French retrospective study.

In primary male to female (MTF) sex reassignment surgery (SRS), the most frequent postoperative functional complications using the penoscrotal skin technique remain neovaginal stenosis, urinary meatal stenosis and secondary revision surgery. We aimed to retrospectively analyze postoperative functional and anatomical complications, as well as secondary procedures required after MTF SRS by penile skin inversion. All patients operated on for MTF SRS, using the inverted technique, from June 2006 to July 2016, were retrospectively reviewed. The minimum follow-up was one year (five-years maximum follow-up). Soft postoperative dilationprotocol was prescribed until complete healing of the vagina. We did not prescribe long-term hard dilation systematically. Possible short-depth neovaginas were primarily treated with further temporary dilation using a hard bougie. Among the 189 included patients, we reported a 2.6% of rectovaginal wall perforations. In 37% of patients we had repeated compressive dressings and 15% of them required blood transfusions. Eighteen percent of patients presented with hematoma and 27% with early infectious complications. Delayed short-depth neovagina occurred in 21% of patients, requiring additional hard dilatation, with a 95.5% success rate. Total secondary vaginoplasty rate was 6.3% (4.7% skin graft and 3.7% bowel plasty). Secondary functional meatoplasty occurred in 1% of cases. Other secondary cosmetic surgery rates ranged between 3 to 20%. A low rate of secondary functional meatoplasty was showed after MTF SRS by penile skin inversion. Hard dilation was prescribed in case of healed short-depth vagina, with good efficiency in most of cases. Secondary vaginoplasty was required in cases of neovagina stenosis or persisting short-depth neovagina after failure of hard dilation protocol.

Rest perfusion abnormalities in hypertrophic cardiomyopathy: correlation with myocardial fibrosis and risk factors for sudden cardiac death.

AIM: To measure the prevalence of abnormal rest perfusion in a population of consecutive patients with known hypertrophic cardiomyopathy (HCM) referred for cardiovascular MRI (CMR), and to assess any associations between abnormal rest perfusion and the presence, pattern, and severity of myocardial scar and the presence of risk factors for sudden death. MATERIALS AND METHODS: Eighty consecutive patients with known HCM referred for CMR underwent functional imaging, rest first-pass perfusion, and late gadolinium enhancement (LGE). RESULTS: Thirty percent of the patients had abnormal rest perfusion, all of them corresponding to areas of mid-myocardial LGE and to a higher degree of segmental hypertrophy. Rest perfusion abnormalities correlated with more extensive and confluent LGE. The subgroup of patients with myocardial fibrosis and rest perfusion abnormalities (fibrosis+/perfusion+) had more than twice the incidence of episodes of non-sustained ventricular tachycardia on Holter monitoring in comparison to patients with myocardial fibrosis and normal rest perfusion (fibrosis+/perfusion-) and patients with no fibrosis and normal rest perfusion (fibrosis-/perfusion-). CONCLUSIONS: First-pass perfusion CMR identifies abnormal rest perfusion in a significant proportion of patients with HCM. These abnormalities are associated with the presence and distribution of myocardial scar and the degree of hypertrophy. Rest perfusion abnormalities identify patients with increased incidence of episodes of non-sustained ventricular tachycardia on Holter monitoring, independently from the presence of myocardial fibrosis.

Sentinel lymph node biopsy in head and neck melanoma*.

AIM: The purpose of this study is to evaluate prognosis and surgical management of head and neck melanoma (HNM) and the accuracy of sentinel lymph node biopsy (SLNB). PATIENTS AND METHODS: All patients with a primary cutaneous melanoma treated starting from 01/07/1994 to 31/12/2012 in the department of Plastic and Reconstructive Surgery of Bari are included in a electronic clinical medical registry. Within the 90th day from excision of the primary lesion all patients with adverse prognostic features underwent SLNB. All patients with positive findings underwent lymphadenectomy. RESULTS: out of 680 patients affected by melanoma, 84 (12.35%) had HNM. In the HNM cohort lymphoscintigraphy was performed in 57 patients, 15 of which (26.3%) were positive. The percentage of unfound sentinel lymph node was similar both to the HNM group (5,26%) and to patients with melanoma of different sites (OMS 4,92%). There was a recurrence of disease after negative SLNB (false negatives) only in 4 cases. Recurrence-free period and survival rate at 5 years were worse in HNM cohort. CONCLUSION: SLNB of HNM has been for a long time contested due to its complex lymphatic anatomy, but recent studies agreed with this technique. Our experience showed that identification of sentinel lymph node in HNM cohort was possible in 98.25% of cases. Frequency of interval nodes is significantly higher in HNM group. The prognosis of HNM cohort is significantly shorter than OMS one. Finally, this procedure requires a multidisciplinary team in referral centers.

Repair of peripheral nerve with vein wrapping.

OBJECTIVE: The post-traumatic neuro-anastomosis must be protected from the surrounding environment. This barrier must be biologically inert, biodegradable, not compressing but protecting the nerve. Formation of painful neuroma is one of the major issues with neuroanastomosis; currently there is no consensus on post-repair neuroma prevention. Aim of this study is to evaluate the efficacy of neuroanastomosis performed with venous sheath to reduce painful neuromas formation, improve the electrical conductivity of the repaired nerve, and reduce the discrepancies of the sectioned nerve stumps. PATIENTS AND METHODS: From a trauma population of 320 patients treated in a single centre between January 2008 and December 2011, twenty-six patients were identified as having an injury to at least one of the peripheral nerves of the arm and enrolled in the study. Patients were divided into two groups. In the group A (16 patients) the end-to-end nerve suture was wrapped in a vein sheath and compared with the group B (10 patients) in which a simple end-to-end neurorrhaphy was performed. The venous segment used to cover the nerve micro-suture was harvested from the superficial veins of the forearm. The parameters analyzed were: functional recovery of motor nerves, sensitivity and pain. RESULTS. Average follow-up was 14 months (range: 12-24 months). The group A showed a more rapid motor and sensory recovery and a reduction of the painful symptoms compared to the control group (B). CONCLUSIONS: The Authors demonstrated that, in their experience, the venous sheath provides a valid solution to avoid the dispersion of the nerve fibres, to prevent adherent scars and painful neuromas formation. Moreover it can compensate the different size of two nerve stumps, allowing, thereby, a more rapid functional and sensitive recovery without expensive devices.

[Acute abdomen due to jejunal perforation secondary to metastatic lung carcinoma]. / Addome acuto da perforazione di metastasi digiunale di carcinoma polmonare operato.

INTRODUCTION: Lung cancer metastases of small bowel are rare (1,1%), often with few or not symptoms. This aspecific onset and the difficult physical-instrumental approach to small bowel, led often to diagnosis at autopsy. This is not true for intestinal metastases that cause complications (haemorrhage, obstruction, perforation); in this cases emergency surgery leds to the diagnosis. CASE REPORT: We describe a case of a male 56 years old patient with acute abdomen due to perforation (X-ray and CT). He refers, about 6 months before, an upper right lobectomy for lung cancer, followed by adjuvant chemo-radiotherapy, because the presence of brain and bone metastases. During the emergency surgery we found out a perforation of the Treitz tract, treated with intestinal resection and immediate end-to-end anastomosis with manual suture. Histological examination shows the perforation of the intestinal wall tract with lung cancer metastases. CONCLUSIONS: Our case shows that any acute abdomen in patient with lung cancer can be considered as expression of intestinal metastases. Negative prognosis of this complication imposes to surgeons only a local treatment.

Cardiovascular autonomic testing in adolescents with type I (insulin-dependent) diabetes mellitus: an 18-month follow-up study.

1. Autonomic abnormalities are frequent in adult patients with diabetes mellitus and progress slowly; little is known about frequency and progression of autonomic abnormalities in childhood. 2. To assess whether autonomic abnormalities are already present in childhood, we evaluated the cardiovascular reflexes, the spectral analysis of spontaneous fluctuations in RR interval and blood pressure (low- and high-frequency), and the baroreflex sensitivity at rest, and after vagal (controlled breathing) and sympathetic activation (tilting) in 25 adolescents with Type I diabetes mellitus, aged 10-17 years, at baseline and after 18 months follow-up, and in 20 age- and sex-matched controls. 3. Cardiovascular reflexes were similar in both patients and controls. Similar significant changes in percentage low- and high-frequency (P < 0.005) from rest to tilting and to control breathing were observed in both patients and controls. The baroreflex sensitivity was also similar in patients and controls. Mild and non-systematic correlations were observed between autonomic tests and disease duration or metabolic control. After 18 months follow-up no changes were observed in any of the measured variables. Correlations with metabolic control remained unchanged. 4. These results indicate a substantial stability of cardiovascular autonomic function in childhood diabetes, and suggest that autonomic abnormalities are likely to develop at an older age.

Origin of respiratory sinus arrhythmia in conscious humans. An important role for arterial carotid baroreceptors.

BACKGROUND: We investigated whether respiratory sinus arrhythmia (RSA) in healthy humans originated from central neuronal oscillations or from peripheral baroreceptors responding to respiratory changes in venous return. METHODS AND RESULTS: During subjects' controlled breathing we used sinusoidal neck suction to influence RSA (spectral analysis of RR interval). In 11 subjects, 20-second apnea greatly reduced RSA, which was restored by neck suction at the frequency of respiration. Counteracting the respiration-induced cycles of carotid blood pressure decreased RSA in 13 subjects (from 2136 +/- 682 to 1372 +/- 561 ms2, P < .01). The critical phase of this neck suction was constant for each subject at around the phase shift (with regard to respiration-related fluctuations of blood pressure) best for smoothing respiratory (mechanical) changes in blood pressure. Suction of a non-baroreceptor area (the thigh) did not affect RSA. In 4 subjects, to separate the effects of peripheral baroreceptor afferents from respiration-entrained central oscillation (15 breaths/min), we cycled the neck suction at 12 cycles/min. Increasing neck suction from -7 to -30 mm Hg increased the ratio of the power of the 12 cycles compared with the 15-cycle RSA oscillation in RR interval spectral analysis from 0.26 to 2.57. A 12-cycle/min suction of an area other than the neck had little effect on the RR interval spectrum. CONCLUSIONS: RSA can be mimicked or reduced by stimulation of arterial baroreceptors with cycles of appropriately phased neck suction at the frequency of respiration. This suggests an important influence of the arterial baroreceptors in the generation of RSA in conscious humans.

Reduction of 0.1 Hz microcirculatory fluctuations as evidence of sympathetic dysfunction in insulin-dependent diabetes.

OBJECTIVE: Loss of spontaneous fluctuations in resting microcirculatory flow has been described in diabetes mellitus, but its mechanism remains unexplained. METHODS: The autonomic control of forearm skin microcirculation was investigated in 23 insulin-dependent diabetic human subjects (median age 39 years, range 27-50) and in 23 age-matched controls (median age 38 years, range 20-57), by laser-Doppler flowmetry. Using spectral analysis of spontaneous microvascular fluctuations, we measured the power of 0.1 Hz ('10-second rhythm') fluctuations, dependent on sympathetic control, and of respiration-related, high-frequency fluctuations, due to the transmission of mechanical chest activity. Autonomic function abnormalities were assessed by 5 tests of cardiovascular reflexes. RESULTS: Abnormalities in cardiovascular autonomic tests were present in 7/23 patients: deep breathing was abnormal 4 in patients, standing in 2, handgrip in 3, cross-correlation in 4, and Valsalva ratio in 0. The power of 0.1 Hz microcirculatory fluctuations was significantly lower in diabetic than in control subjects (2.57 +/- 0.16 vs 3.48 +/- 0.09 In-mV2, mean +/- s.e.m., P < 0.001), whereas that of respiratory fluctuations was similar (2.60 +/- 0.24 vs 2.56 +/- 0.19 In-mV2, P = n.s.). The 0.1 Hz power was 2 standard deviations below the mean of controls (P < 0.05) in 13/23 diabetic patients; this abnormality was significantly more frequent than abnormalities in any other autonomic test (P < 0.001). CONCLUSIONS: Since the observed reduction was confined to those microvascular fluctuations under autonomic control, but not to those dependent on passive mechanical transmission, the reduction in spontaneous microcirculatory vasomotion appears to be determined mainly by sympathetic dysfunction. Sympathetic impairment of skin microvascular control seems to be a common finding, and is probably an early index of autonomic dysfunction in insulin-dependent diabetes.

Lack of peripheral modulation of cardiovascular central oscillatory autonomic activity during apnea in humans.

Respiratory sinus arrhythmia (RSA) high-frequency oscillations (HF) and slow fluctuations in heart rate (LF) are thought to result from entrainment of a medullary oscillator, from the baroreflex, or from a combination of both central and baroreflex mechanisms. We sought to distinguish between the alternatives by examining with spectral analysis the behavior of heart rate (R-R interval) and blood pressure in 10 healthy subjects (mean age 27 +/- 1 yr) during apnea, altering the rate of preapnea entrainment stimuli by changing the frequency either of respiration (controlled at 0.1 or 0.25 Hz) or of baroreceptor stimulation by sinusoidal neck suction (0 to -30 mmHg, 0.1 or 0.2 Hz). During apnea the RSA-EF power decreased (from 6.73 +/- 0.15 to 3.67 +/- 0.10 In ms2: P < 0.0001), regardless of preapnea conditions, whereas LF power was reduced only if preceded by 0.1-Hz respiration or neck suction [from 8.71 +/- 0.18 to 6.52 +/- 0.11 In ms2 (P < 0.001) and from 8.31 +/- 0.23 to 6.90 +/- 0.38 In ms2 (P < 0.01), respectively]. The LF frequency seen in the R-R interval during apnea was slower than the spontaneous LF during 0.25-Hz breathing (0.082 +/- 0.01 vs. 0.112 +/- 0.001 Hz, P < 0.001), but the maneuvers during preapnea had no influence on the observed frequency or other characteristics of the slow oscillations during apnea. Moreover, we found no evidence of a progressive decrease in the power of the oscillation during apnea. The same behavior was observed on the mean blood pressure signal. In conclusion, a slow rhythm is present during apnea. In healthy subjects at rest the characteristics of this oscillation indicate that it could be generated by a central oscillator this may thus contribute to the origin of LF present during normal respiration, in addition to the baroreflex.

Determinants of heart rate variability in heart transplanted subjects during physical exercise.

Respiratory sinus arrhythmia has been described in heart transplanted subjects. In order to investigate the mechanisms involved in the generation of this condition in the transplanted heart and its evolution after surgery, graded exercise was performed (0-75 W in 25 W steps) on a cycle ergometer by 41 subjects (mean age 44 years) who had undergone heart transplantation 28 months (range 3-60) earlier and by six age matched-control subjects. R-R interval, respiratory signal, O2 consumption (VO2) and CO2 production (VCO2) were measured. Respiratory sinus arrhythmia was assessed by the autoregressive power spectrum of the R-R interval and respiration. All subjects reached the anaerobic threshold (heart transplants: 60% at 50 W, 40% at 75 W Controls: 150 W). In control subjects, the respiratory sinus arrhythmia was higher than in heart transplanted subjects (5.80 +/- 0.30 vs 1.45 +/- 0.16 1n ms2) and it decreased significantly (4.66 +/- 0.30 1n ms2, P < 0.05) during exercise, despite the increase in breathing rate and depth. When, the group of heart transplanted subjects was considered as a whole, respiratory sinus arrhythmia was found to be present in all conditions. It significantly increased at 25 W (from 1.45 +/- 0.16 to 2.00 +/- 0.17 1n ms2, P < 0.01), then significantly fell below baseline during recovery (to 0.97 +/- 0.23 1n ms2, P < 0.01). Multiple regression analysis showed that a linear combination of heart rate (inverse correlation) and VO2 (direct correlation) together with months having passed since transplantation surgery, could explain the observed changes in heart rate during exercise (multiple regression: r = 0.658, P < 0.0001). In five long-term transplanted subjects, non respiratory-related low frequency (0.1 Hz) waves were present on the R-R spectrum, but respiratory sinus arrhythmia is also present in the recently transplanted heart and depends on the opposing effects of ventilation and heart rate. In a few cases, sympathetic modulation (re-innervation) could not be excluded.

Effect of different interventions on heart rate variability after heart transplantation: non-autonomic vs autonomic factors.

1. The human transplanted heart is initially denervated, hence any fluctuation present in the RR interval variability can be either due to reacquired innervation, or to the effect of some non autonomic activity, such as a direct effect of respiration on atrial (sinus node) stretch. 2. In order to distinguish between sympathetic, vagal and non autonomic factors we examined the effects of various physical and pharmacologic manoeuvres on the respiratory and non-respiratory components of heart rate variability. 3. We found that sinusoidal neck suction appears a useful, noninvasive tool to characterise the relative importance of the different factors, which can influence heart rate variability in the transplanted heart.

Cardiovascular reflex changes preceding episodes of vasovagal syncope in paediatric subjects.

1. The cardiovascular reflex changes preceding episodes of vasovagal syncope (VVS) in paediatric age were investigated in 12 subjects and in 20 controls, supine and upright, by spectral analysis of RR interval, respiration, systolic and diastolic blood pressure. 2. The sympatho-vagal control on the heart and blood pressure was assessed by the power of the low- (LF: index of sympathetic activity) and high-frequency oscillations (index of vagal activity to the heart). 3. In VVS group the supine blood pressure was lower than in controls and fell after tilt, while remained unchanged in controls. The blood pressure LF increased in control group during early and prolonged orthostasis, whereas in the VVS group the LF tended to decrease after early orthostasis and were not significantly greater than supine before VVS. 4. In the VVS group the sympathetic control of blood pressure appears reduced or ineffective, and progressively worsens before the VVS episode.

Physical training enhances sympathetic and parasympathetic control of heart rate and peripheral vessels in chronic heart failure.

1. Physical training has been proposed to increase vagal control of heart rate in chronic heart failure. We studied the effects of physical training on cardiovascular control in 6 moderate to severe heart failure (NYHA II-III) patients and 6 age matched normal controls in a randomized controlled cross over trial (Training vs Detraining). 2. Five weeks training (20 min/day, 5 days/week bicycle exercise) increased peak VO2 in both C (from 31.2 +/- 1.4 to 37.7 +/- 2.4 ml/kg/min p < 0.01) and CHF patients (from 12.16 +/- 2.2 to 14.13 +/- 2 ml/kg/min p < 0.05). The sympathovagal control of heart rate and sympathetic control of the resistance vessels was assessed by the power of the oscillations (LF:0.03-0.15 Hz index of sympathetic activity, HF: 0.18-0.35 Hz index of vagal activity) in RR interval, blood pressure (systolic and diastolic by Finapres) and respiration by autoregressive spectral analysis, during free and controlled breathing (15b/min), in order to increase vagal activity. 3. T increased heart rate vagal control both in C (LF/HF ratio fb to cb: (D) 1.73 +/- 0.35 to 1.19 +/- 0.43 p = NS: (T) 2.9 +/- 1.2 to 1.13 +/- 0.3 p < 0.05) and in CHF patients (LF/HF ratio fb to cb: (D) 2.05 +/- 0.56 to 1.24 +/- 0.21 p = NS; (T) 2.6 +/- 0.89 to 0.87 +/- 0.15 p < 0.05; and in cb HF%: 36.2 +/- 2.7 (D) to 46.2 +/- 4.8 (T) p < 0.05). Before T, the sympathetic modulation of peripheral vessels (% LF compared to total variability) was depressed in CHF vs C (SBP: 9 +/- 2 vs 42 +/- 12% p < 0.05; DBP: 29 +/- 7 vs 55 +/- 31%, p < 0.05), and increased significantly after T in CHF (SBP from 9 +/- 2 (D) to 19 +/- 5% (T) p < 0.05; DBP from 29 +/- 7 to 41 +/- 11% (T) p < 0.05). This suggests an overall increase of autonomic control, both vagal on the heart and sympathetic on the peripheral vessels, in CHF by physical training.

Demonstrable cardiac reinnervation after human heart transplantation by carotid baroreflex modulation of RR interval.

BACKGROUND: After heart transplantation, respiration-synchronous fluctuations (0.18 to 0.35 Hz, high frequency [HF]) in RR interval may result from atrial stretch caused by changes in venous return, but slower fluctuations (0.03 to 0.15 Hz, low frequency [LF]) not due to respiration suggest reinnervation. In normal subjects, sinusoidal neck suction selectively stimulates carotid baroreceptors and causes reflex oscillations of RR interval. METHODS AND RESULTS: To evaluate the presence of reinnervation, we measured the power of RR-LF and RR-HF in 26 heart transplant recipients and 16 control subjects before and during sinusoidal neck suction at 0.1 Hz and 0.20 Hz (similar to but distinct from that of controlled respiration, 0.25 Hz) and before and during administration of atropine or beta-blocker (esmolol hydrochloride) by spectral analysis. All transplant recipients showed small respiratory HF fluctuations. Nonrespiratory LF fluctuations were present in 13 of 26 transplant recipients and increased with months since transplantation (r = .53, P < .01). HF neck suction induced a 0.20-Hz component in all 16 control subjects and none of the 26 transplant subjects. LF neck suction increased RR-LF (from 0.73 +/- 0.20 to 1.30 +/- 0.26 ln ms2, P < .001), similar to but less than in control subjects (from 6.12 +/- 0.21 to 8.27 +/- 0.21 ln ms2, P < .001). Atropine reduced all fluctuations in control subjects and blocked the HF increase caused by 0.20-Hz neck suction but not the LF increase during 0.10-Hz stimulation. Neck suction-induced changes in LF fluctuations persisted after administration of atropine in transplant recipients but were attenuated by esmolol hydrochloride, suggesting sympathetic rather than vagal reinnervation. CONCLUSIONS: The presence of baroreceptor-induced RR oscillations is evidence of functional, although incomplete, autonomic reinnervation.

Physiology and pathophysiology of heart rate and blood pressure variability in humans: is power spectral analysis largely an index of baroreflex gain?

1. It is often assumed that the power in the low- (around 0.10 Hz) and high-frequency (around 0.25 Hz) bands obtained by power spectral analysis of cardiovascular variables reflects sympathetic and vagal tone [corrected] respectively. An alternative model attributes the low-frequency band to a resonance in the control system that is produced by the inefficiently slow time constant of the reflex response to beat-to-beat changes in blood pressure effected by the sympathetic (with or without the parasympathetic) arm(s) of the baroreflex (De Boer model). 2. We have applied the De Boer model of circulatory variability to patients with varying baroreflex sensitivity to patients with varying baroreflex sensitivity and one normal subject, and have shown that the main differences in spectral power (for both low and high frequency) between and within subjects are caused by changes in the arterial baroreflex gain, particularly for vagal control of heart rate (R-R interval) and left ventricular stroke output. We have computed the power spectrum at rest and during neck suction (to stimulate carotid baroreceptors). We stimulated the baroreceptors at two frequencies (0.1 and 0.2 Hz), which were both distinct from the controlled respiration rate (0.25 Hz), in both normal subjects and heart failure patients with either sensitive or poor baroreflex control. 3. The data broadly confirm the De Boer model. The low-frequency (0.1 Hz) peak in either R-R or blood pressure variability) was spontaneously generated only if the baroreflex control of the autonomic outflow was relatively intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Low-frequency spontaneous fluctuations of R-R interval and blood pressure in conscious humans: a baroreceptor or central phenomenon?

1. We have tested the hypothesis that the non-respiratory, low-frequency (around 0.1 Hz) fluctuations of heart rate variability are generated by the baroreflexes, but with a delay caused by the slower response of the efferent sympathetic arm, (compared with the vagus), in 11 healthy subjects (mean age +/- SD 27 +/- 5 years). 2. In random order, at the onset of 20 s of apnoea starting at end expiration, we applied either 600 ms neck suction (-40 mmHg) to the carotid sinus region, or no stimulus (anticipation control), or a loud whistle (alerting control), every 60 s, for 30 min. (i.e. 10 of each 'stimulus'). We recorded neck pressure, blood pressure (Finapres), R-R interval (ECG), infra-red plethysmographic skin blood flow and respiration (impedance). By subtracting the alerting response from the neck suction response we obtained the responses caused purely by baroreceptor stimulation. 3. The initial reflex bradycardia and hypotension was followed by arteriolar vasoconstriction, presumably due to recompensation by the baroreflex, and then by a further reflex bradycardia-producing a decaying oscillation of the R-R interval about the control R-R. The period of this damped oscillation was 0.103 +/- 0.024 Hz, similar to the frequency of the low-frequency peak obtained by power spectral analysis of heart rate variability (0.093 +/- 0.016 Hz, not significant) at rest. These two values were significantly correlated in individual subjects (r = 0.715, P < 0.025). 4. These findings support the hypothesis that the low-frequency waves of heart rate variability can be generated from baroreceptor sensed blood pressure fluctuations.

[The noninvasive demonstration of functional reinnervation after heart transplantation]. / Dimostrazione non invasiva di reinnervazione funzionale dopo trapianto cardiaco.

Although RR interval variability appears to be an ideal method for assessing reinnervation after heart transplantation, it has been shown that respiratory sinus arrhythmia is caused by the mechanical effect of respiration on the right atrium. The neck-suction induces heart rate changes only by means of nervous reflex and its hemodynamic effect is local and hence appears as a useful method for assessing reinnervation. We tested the presence of autonomic reinnervation in 18 heart transplant recipients, compared to 12 donor-age-matched controls. We measured the power of RR interval low- (LF, around 0.1 Hz) and respiratory fluctuations (HF) before and during rhythmic neck-suction stimulation at 0.1 Hz and at a frequency (0.20 Hz) similar to, but distinct from, that of respiration (controlled at 0.25 Hz), before and during 0.04 mg/kg atropine infusion, using autoregressive spectral analysis of RR interval, respiration and neck pressure signals. The relationship between pairs of signals at each frequency was quantitatively assessed by bivariate coherence function. All transplanted subjects showed low-amplitude HF, related to respiration. Detectable LF (whose power was lower than in controls: 1.15 +/- 0.39 versus 6.08 +/- 0.27 1n-ms2, p < 0.001), non coherent with respiration, were present in 11/18 transplanted subjects, and correlated with months since transplantation (r = +0.59, p < 0.05). HF neck suction induced the presence of a 0.20 Hz fluctuation in 12/12 controls, distinct from and greater than the 0.25 Hz respiratory component (7.28 +/- 0.26 versus 6.69 +/- 0.74 1n-ms2, p < 0.01); this was not seen in any of the transplanted subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular autonomic modulation in essential hypertension. Effect of tilting.

To better understand the role played by the autonomic nervous system in essential hypertension, we used autoregressive power spectrum analysis to study the noncasual oscillations in RR interval, blood pressure, and skin blood flow in 40 subjects with mild to moderate hypertension and in 25 age-matched control subjects at low frequency (index of sympathetic activity to the heart and the peripheral circulation) and high frequency, respiratory related (index of vagal tone to the heart). RR interval, respiration, noninvasive systolic blood pressure, and skin arteriolar blood flow were simultaneously and continuously recorded with subjects in the supine position and immediately after tilting. The low-frequency component was not significantly different in the two groups either at the cardiac level (control versus hypertensive subjects: 39.1 +/- 4.3 versus 39.9 +/- 3.7 normalized units [NU]) or at the vascular level (1.52 +/- 0.17 versus 1.69 +/- 0.13 ln mm Hg2). After head-up tilting, the RR interval fluctuations were less in hypertensive subjects (low-frequency components from 39.9 +/- 3.7 to 48.4 +/- 4.1 NU, P < .05; high-frequency components from 53.9 +/- 3.7 to 44 +/- 4 NU, P < .05) than in control subjects (low-frequency components from 39.1 +/- 4.3 to 64.4 +/- 4.9 NU, P < .001; high-frequency components from 56.0 +/- 4.5 to 31.2 +/- 4.6 NU, P < .001); the low-frequency components in systolic blood pressure increased similarly in hypertensive subjects (to 2.43 +/- 0.17 ln mm Hg2, P < .0001) and in control subjects (to 2.44 +/- 0.21 ln mm Hg2, P < .01), but the low-frequency components in skin blood flow increased only in control subjects (from 5.34 +/- 0.45 to 6.55 +/- 0.53 mm Hg2, P < .01), not in hypertensive subjects (from 5.55 +/- 0.34 to 5.60 +/- 0.35 ln mm Hg2). In hypertensive subjects with left ventricular hypertrophy, the low-frequency components in systolic blood pressure did not increase after tilting (from 1.75 +/- 0.33 to 2.05 +/- 0.41 ln mm Hg2). Baroreflex sensitivity, as assessed by spectrum analysis, was significantly lower in hypertensive than in control subjects (5.17 +/- 0.49 versus 13.18 +/- 2.44 ms/mm Hg, P < .001. Power spectrum analysis did not reveal an increased sympathetic activity or reactivity either at the cardiac or at the vascular level. The decreased baroreceptor sensitivity in hypertensive subjects could explain the reduced change in sympathovagal balance in the tilt position at the cardiac level. In hypertensive subjects without left ventricular hypertrophy, cardiopulmonary reflex deactivation induced by tilting and/or amplification of sympathetic nervous tone by arteriolar structural change could have preserved the sympathetic activation at the vascular level.