Aortic End Research Articles

Novel Technique for Proximal Anastomosis of Vein Graft to Right Coronary Artery

A novel technique for anastomosis of the proximal (aortic) end of the saphenous vein conduit to the right coronary territory is described. This has proved to be an excellent technique that can be performed expeditiously with minimal assistance. It is easily reproducible with consistent results, even for surgeons in the initial stages of their learning curves.

Hemodynamic effects of methadone and dihydrocodeine in overdose

Background. Opioid overdose is an increasing health problem worldwide. The cardiovascular toxicity of opioids contributes to morbidity and mortality in overdose but the hemodynamic effects of opioids reported in animal and human studies are contradictory. Methods. We performed a prospective observational study of patients admitted to hospital following an overdose of methadone, dihydrocodeine, or low dose paracetamol (10 each). Basic cardiovascular indices including peripheral blood pressure, pulse rate, radial augmentation index and derived measures of aortic systolic, diastolic, pulse, and mean and end systolic pressures were measured every six hours for up to 18–23 hours after exposure or until hospital discharge. Results. Dihydrocodeine and methadone significantly reduced peripheral and aortic systolic, mean and end systolic pressures. Both opioids significantly decreased peripheral pulse pressure, but only methadone decreased aortic blood pressure. Dihydrocodeine reduced systemic and aortic diastolic blood pressure, an effect not induced by methadone. Methadone significantly reduced peripheral pulse pressure. Augmentation index and heart rate, however, did not change. Both opioids decreased arterial oxygen saturation. Conclusion. These results suggest that dihydrocodeine and methadone in overdose both have a significant effect on central and peripheral hemodynamics. These effects might be expected to reduce cardiac afterload, providing a pharmacological explanation for the apparent benefit of opioids in cardiovascular diseases.

Patent Ductus Arteriosus

The patent ductus arteriosus (PDA) is a vascular structure that connects the proximal descending aorta to the roof of the main pulmonary artery near the origin of the left branch pulmonary artery. This essential fetal structure normally closes spontaneously after birth. After the first few weeks of life, persistence of ductal patency is abnormal. The physiological impact and clinical significance of the PDA depend largely on its size and the underlying cardiovascular status of the patient. The PDA may be “silent” (not evident clinically but diagnosed incidentally by echocardiography done for a different reason), small, moderate, or large. Regardless of the size, complications may arise, and it is important for both pediatric and adult cardiologists to have an understanding of the pathophysiology, clinical implications, and management of PDA. The ductus arteriosus is a normal and essential fetal structure that becomes abnormal if it remains patent after the neonatal period. In normal cardiovascular development, the proximal portions of the sixth pair of embryonic aortic arches persist as the proximal branch pulmonary arteries, and the distal portion of the left sixth arch persists as the ductus arteriosus, connecting the left pulmonary artery with the left dorsal aorta (Figure 1). Normally, the distal right sixth aortic arch loses its connection to the dorsal aorta and degenerates. This transformation is complete by 8 weeks of fetal life. Figure 1. Schematic of embryonic aortic arch system. The 6 pairs of embryonic aortic arches are demonstrated (left-sided arches are numbered). The portions that normally involute are indicated by broken lines. The distal left sixth embryonic arch normally persists and becomes the PDA, connecting the left pulmonary artery to the proximal descending aorta. The right distal sixth arch normally involutes, as does the eighth segment of the right dorsal aorta (*), which results in a leftward aortic …

Typical echocardiographic appearance of a ruptured sinus of Valsalva aneurysm in a previously healthy 30-year-old man

Fig. 1. Transverse midesophageal plane at 458, demonstrating the short axis of the aortic valve in diastole. The ruptured aneurysm of the right coronary sinus protrudes into the right atrium just above the tricuspid valve producing the characteristic ‘windsock’ appearance described in textbooks. Colour-flow Successful surgical repair of a ruptured sinus of Valsalva aneurysm was performed in a 30-year-old man, presenting with acute onset dyspnoea. Transoesophageal echocardiography demonstrated the characteristic ‘windsock’ appearance of the aneurysm described in textbooks and the continuous flow between the aorta and the right atrium corresponding to a continuous murmur. During surgery an 8 mm opening was identified in the right coronary sinus leading into the right atrium, the aneurysm tissue in the right atrium was excised and the base oversewn, whilst a patch of pericardium was used to close the defect from the aortic end (Figs. 1 and 2). Doppler demonstrates continuous blood flow through the ruptured aneurysm between the aorta and the right atrium, corresponding to the continuous murmur. RA (right atrium), LA (left atrium), RV (right ventricle), TV (tricuspid valve), PV (pulmonary valve), PA (pulmonary artery), LCC (left coronary cusp), NCC (non-coronary cusp), RCC (right coronary cusp). Appendix. Supplementary material

Comparison of effects of uncomplicated canine babesiosis and canine normovolaemic anaemia on abdominal splanchnic Doppler characteristics - a preliminary investigation

A preliminary study was conducted to compare uncomplicated canine babesiosis (CB) and experimentally induced normovolaemic anaemia (EA) using Doppler ultrasonography of abdominal splanchnic vessels. Fourteen dogs with uncomplicated CB were investigated together with 11 healthy Beagles during severe EA, moderate EA and the physiological state as a control group. Canine babesiosis was compared with severe EA, moderate EA and the physiological state using Doppler variables of the abdominal aorta, cranial mesenteric artery (CMA), coeliac, left renal and interlobar, and hilar splenic arteries, and the main portal vein. Patterns of haemodynamic changes during CB and EA were broadly similar and were characterised by elevations in velocities and reductions in resistance indices in all vessels except the renal arteries when compared with the physiological state. Aortic and CMA peak systolic velocities and CMA end diastolic and time-averaged mean velocities in CB were significantly lower (P < 0.023) than those in severe EA. Patterns of renal haemodynamic changes during CB and EA were similar. However, the renal patterns differed from those of aortic and gastrointestinal arteries, having elevations in vascular resistance indices, a reduction in end diastolic velocity and unchanged time-averaged mean velocity. The left renal artery resistive index in CB was significantly higher (P < 0.025) than those in EA and the physiological state. Renal interlobar artery resistive and pulsatility indices in CB were significantly higher (P < 0.016) than those of moderate EA and the physiological state. The similar haemodynamic patterns in CB and EA are attributable to anaemia, while significant differences may additionally be attributed to pathophysiological factors peculiar to CB.

Fetal echocardiographic diagnosis of isolated ductus arteriosus aneurysm: a longitudinal study from 32 weeks of gestation to term

To investigate the echocardiographic characteristics of isolated fetal ductus arteriosus aneurysm (DAA) and the factors influencing its development. Fetal echocardiograms for 509 low-risk singleton pregnancies were performed longitudinally from 32 weeks of gestation. The ventricular outflow tracts and great vessels were visualized, focusing on changes in the ductus arteriosus (DA), and fetuses with DAA or ductus arteriosus dilatation (DAD) were identified. Prenatal and perinatal findings were compared between those infants diagnosed postnatally with and those without neonatal DAA. Forty-one of the 509 fetuses (8.1%) studied had neonatal DAA; 2.2% (11/509) had DAA and 5.9% (30/509) DAD before delivery. The mean gestational age at the time of diagnosis of fetal DAA/DAD was 36.9 +/- 1.7 weeks. The mean maximal internal diameter of DAA/DAD was 8.0 +/- 0.8 mm at initial diagnosis, increasing to 10.8 +/- 1.6 mm before delivery. All cases originated from the aortic end of the DA. Compared with fetuses without neonatal DAA, the affected cases had a markedly more curved DA prior to diagnosis, and higher peak velocities at the aortic end of the DA (P < 0.05). Newborns with fetal DAA/DAD had a larger placental weight to birth body weight (BBW) ratio and were less likely to have a BBW appropriate for gestational age (P < 0.05). All cases of fetal DAA/DAD regressed spontaneously. Isolated neonatal DAA is a continuity of fetal DAA/DAD. The development of fetal DAA/DAD is likely to be related to the higher peak velocities in the more markedly curved DA occurring in the latter part of the third trimester. Fetal DAA/DAD usually initiates at the aortic end of the DA, followed by progression towards the pulmonary end.

Comparison of Pulsatile With Nonpulsatile Mechanical Support in a Porcine Model of Profound Cardiogenic Shock

The aim of this study was to examine whether pulsatility by intraaortic balloon counterpulsation (IABP) is an important adjunct to the treatment of profound cardiogenic shock (CS) with a widely used, nonpulsatile centrifugal pump (CP). In each of 18 anesthetized, open chest pigs, the outflow cannula of the CP was inserted in the aortic arch through the right external carotid artery, and the inflow cannula of the CP was placed in the left atrium. A 40 cc IABP was subsequently placed in the descending aorta through the left external carotid artery. CS was induced by occlusion of coronary arteries and the infusion of propranolol and crystalloid fluid. Mean aortic pressure, pulse pressure, aortic end diastolic pressure, left ventricular end diastolic pressure, right atrial pressure, and heart rate were monitored. Cardiac output and left anterior descending artery flow were measured with a transit time ultrasound flowmeter. During profound CS, life sustaining hemodynamics were maintained only with the support of the assist devices. Hemodynamic support with the CP was associated with a nearly nonpulsatile flow and a pulse pressure of 7 +/- 4 mm Hg, which increased to 33 +/- 10 mm Hg (p = 0.000) after combining the CP with the IABP. Compared with the hemodynamic support offered by the CP alone, addition of the IABP increased mean aortic pressure from 40 +/- 15 to 50 +/- 16 mm Hg (p = 0.000), cardiac output from 810 +/- 194 to 1,200 +/- 234 ml/min (p = 0.003), and left anterior descending artery flow from 26 +/- 10 to 39 +/- 14 ml/min (p = 0.001). In profound CS, mechanical support provided by a continuous flow CP is enhanced by the added pulsatility of the IABP.

Left ventricular form and function: scientific priorities and strategic planning for development of new views of disease.

Heart failure continues to be one of the most costly and prevalent medical problems. The increasing age of our population and the increased survival of patients with diseases that lead to heart failure will no doubt further magnify this very serious health problem at a staggering cost, both monetary and human. To address this public health concern, a fuller understanding of what constitutes normal cardiac function is essential to recognize optimal goals for restoration after disease disrupts stability. From micro to macro, our limited understanding of the heart’s function continues to represent an obstacle to our ability to design strategies for effective treatment of heart failure. Thus, there is a critical need to address the existing and emerging issues in this area to develop new safe and effective strategies to address the clinical challenges facing cardiologists and cardiothoracic surgeons. As a result of this need, the National Heart, Lung, and Blood Institute convened a workshop entitled “Form and Function: New Views on Development, Diseases, and Therapies for the Heart” on April 25 to 26, 2002, in Bethesda, Maryland. The objective was an effort to understand the importance of structure/function relationships of the intact ventricles from both the basic science and clinical perspectives, to define where progress is most urgently needed, and to plan research programs that will most effectively integrate understanding of functional geometry into therapy of human heart disease.

Aortico–left ventricular tunnel: 35-year experience

ObjectivesThe purpose of this study was to review our 35 years of experience with aortico–left ventricular tunnel (ALVT), with emphasis on diagnosis, surgical details, and follow-up. BackgroundAortico–left ventricular tunnel is a rare congenital anomaly. Neonatal surgery has been advocated in all due to long-term concern of valvar aortic regurgitation (AR). MethodsWe identified 11 patients from 1963 to August 2002. Clinical, echocardiographic, catheterization, and surgical details were reviewed. ResultsEight of 11 patients presented at less than six months old (six with congestive heart failure) and three later with a murmur, all with clinical evidence of AR. Associated lesions, most commonly aortic valve and coronary artery anomalies, were present in 45%. Catheter occlusion was considered but not performed in five. Spontaneous occlusion was documented in one. Ten had surgery (nine in our institution), seven with direct suture and two by patch closure of the aortic end of the AVLT. At follow-up (median, 5 years; 1 month to 35 years), all were asymptomatic; three had residual ALVT (one moderate, two small/trivial), with at most mild AR. ConclusionsAortico–left ventricular tunnel is a rare cardiac malformation with a good post-operative long-term outcome. Associated lesions occurred in 45%. Catheterization should be reserved for patients with unclear non-invasive findings or transcatheter closure. We recommend surgery for most patients. We report spontaneous closure in one patient, prompting consideration of conservative follow-up in rare small, asymptomatic AVLT.

Long-term durability of resection and end-to-end anastomosis for ascending aortic aneurysms

Background Ascending aortic aneurysms with normal sized sinotubular junction are generally treated by resection of the dilated aorta and replacement with tubular graft. Aortic resection and direct end-to-end anastomosis has been applied to repair aortic coarctation, interrupted aortic arch, and traumatic aortic rupture. No data exist regarding the long-term durability of this approach in ascending aortic aneurysms. The aim of this case-control study was to illustrate the durability of this operation by presenting our entire experience and the long-term follow up of a cohort of 34 patients who underwent ascending aortic aneurysm resection and primary end-to-end anastomosis between January 1990 and March 2003 in Caen University Hospital (Caen, France). Methods The mean age of patients was 61.5 ± 12.5 years, and there were 18 male and 16 female patients. The operative technique included extensive mobilization of the arch, supra-aortic trunks, and inferior vena cava to enable approximation of the aortic ends, thus avoiding tension on the suture lines. Associated aortic valve replacement was performed in 27 patients; mechanical valves were used in 19. A bicuspid aortic valve was present in 9 patients; in 3 cases the valve was regurgitant. Aortic valve regurgitation was present in a total of 7 patients. Patients were followed up at regular intervals; total follow-up was 2187 patient-months, with a median follow-up time of 72 months per patient (25th-75th percentile 10.5-102.7 months). Results One patient died 10 days after the operation of aortic rupture related to suture infection caused by mediastinitis. Late deaths occurred in 3 patients, who died 12, 62, and 71 months after the operation, but none of these deaths were attributable to late aortic repair failure. No patient in this series required reoperation, including patients with aortic regurgitation or bicuspid aortic valve. Follow-up was 91.1% complete at the closing date of April 1, 2003. The Kaplan-Meier estimate of survival for all patients was 120.4 months (95% confidence interval 105.1-135.7 months). The median of preoperative maximal aortic diameter was 55.1 mm (range 50.3 to 67.5 mm, 25th-75th percentile 50.5-56.8 mm). The median immediate postoperative diameter was 40.3 mm (range 33.4-46.4 mm, 25th-75th percentile 37.2-42.0 mm, P < .0001 relative to preoperative diameter), and the median length of the resected aortic segment was 52 mm (range 48-76 mm, 25th-75th percentile 50.1-66.4 mm). The median decrease of aortic diameter was 24.9 mm (range 8.9-32.6 mm, 25th-75th percentile 18.2-26.6 mm).The median aortic diameter at the end of the follow-up was 41.0 mm (range 34.6-46.1 mm, 25th-75th percentile 37.0-43.2 mm, P = .6 relative to immediate postoperative diameter). Conclusions Ascending aorta aneurysm resection and primary end-to-end anastomosis provides effective long-term outcome and in selected cases represents a good alternative to aortic interposition grafting. Aortic regurgitation and bicuspid aortic valve do not represent a contraindication for this treatment

The unrecognized physiological and clinical significance of the fetal aortic isthmus

An undisputed feature of fetal circulatory dynamics is that the two ventricular pumps perfuse the same systemic circulation in a parallel fashion. Under normal conditions, the blood ejected by the right ventricle (RV) perfuses the subdiaphragmatic organs and carcass, with approximately 10–15% going into the pulmonary circulation, while the cephalic part of the fetus receives blood exclusively from the left ventricle (LV)1,2. Another generally accepted characteristic of the fetal circulation is the presence of intracardiac and extracardiac shunts; among the latter is the ductus arteriosus (DA). Although the fetal DA is actually part of the normal vascular outlet of the RV forming ‘the pulmonary arch’ with the main pulmonary artery (MPA) and descending thoracic aorta (DAo), its recognition as a vascular shunt has never been an issue for physiologists and perinatologists. Yet, a shunt, as defined in an electrical circuit, joins two points of the network and ‘serves to divert part of the current’3. In postnatal life, where the ventricles are disposed in series, a patent DA does indeed divert blood from either the systemic or the pulmonary circulation, depending on the downstream impedances of the two circulatory systems. In fetal life, if blood flow going through the pulmonary arch down into the DAo had to be considered as a right-to-left shunt taking blood away from the lungs, then the two ventricles would have to be regarded as disposed in series as in postnatal life; the classical description of the parallel ventricular arrangement would then become irrational. The concept of a fetal circulation based on two circulatory systems arranged in parallel fashion (a concept which is fully justified) is incompatible with the identification of the DA as a shunt. In utero, the arterial vascular segment that conforms to the definition of, and behaves like, a shunt is the aortic isthmus. Indeed, the isthmus, located between the origin of the left subclavian artery and the aortic end of the DA, establishes communication between the two arterial outlets that perfuse in parallel the upper and lower body of the fetus (Figure 1a). This logical approach bears not only physiological significances but could have many clinical implications, especially with the advent of Doppler ultrasound in fetal monitoring.

Comprehensive assessment of patent ductus arteriosus by echocardiography before transcatheter closure

Background: Anatomic type and angiographic measurements of patent ductus arteriosus (PDA) are used to determine the suitability of transcatheter closure (TCC). The purpose of this study is to evaluate whether these PDA features can be obtained by 2-dimensional echocardiography (2DE). Methods: We retrospectively compared PDA measurements and type from 36 patients submitted to TCC between November 1995 and October 2000. Results: The patient age ranged between 2 months to 10.5 years (median = 1.2 years). A significant correlation was found between measurements of PDA minimal diameter ( R 2 = 0.88) and diameter at aortic ostium ( R 2 = 0.72); whereas a poor correlation existed between measurements of the ampulla length. The 2DE and angiographic PDA classification were concordant in 31 of 36 (86%) patients. Conclusion: Our data support the use of 2DE measurements of PDA minimal diameter and PDA diameter at the aortic end to assess suitability for TCC. In the majority of cases, PDA type can be diagnosed by 2DE. (J Am Soc Echocardiogr 2002;15:1154-9.)

Successful two patch repair of the aortico-left ventricular tunnel

A 7-month-old boy with aortico-left ventricular tunnel arising from the right coronary sinus underwent surgical correction using the two patch technique. The diagnosis was confirmed by 2D and Doppler echocardiogram alone. Patch closure of both the aortic and ventricular ends of the tunnel is recommended in order to prevent postoperative aortic regurgitation and recurrence of the lesion.

A preliminary study of the application of the transductal velocity ratio for assessing persistent ductus arteriosus

OBJECTIVETo compare the transductal velocity ratio (TVR) of the persistent ductus arteriosus (PDA) with other echocardiographic criteria for haemodynamic significance of a PDA.METHODSThis was a prospective study (from January 1997...

Congenital Heart Surgery Nomenclature and Database Project: aortico-left ventricular tunnel

The extant nomenclature for aortico-left ventricular tunnel is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. Efforts were made to include all relevant nomenclature categories using synonyms where appropriate. The Hovaguimian classification appears most useful to surgeons: type 1, a simple tunnel with a slit-like opening at the aortic end, no aortic valve distortion; type II, a large extracardiac aortic wall aneurysm of the tunnel with an oval opening at the aortic end, with or without ventricular distortion; type III, intracardiac aneurysm of the septal portion of the tunnel, with or without right ventricular outflow tract obstruction; and type IV, a combination of type II and III. A comprehensive database set is presented, which is based on a hierarchical scheme. Data are entered at various levels of complexity and detail, which can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented which will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Endothelialization of the Coils Used to Occlude a Persistent Ductus Arteriosus

To assess the endothelialization of the coils used to close a persistent ductus arteriosus (PDA), the present study comprised a review of the follow-up aortograms and pulmonary angiograms in 25 patients who underwent coil occlusion. The minimal diameter and the length of the PDA were measured prior to the procedure, and the shortest distance between the aortic end of the deployed coil and the aortic end of the PDA was measured after coil deployment. Evidence of endothelial coverage of the coil was sought on follow-up angiograms performed 6-24 (15+/-5) months later and the factors that determined the thickness of the endothelial coverage on the aortic end were investigated. Separation of the coil and the contrast column were detected at the aortic end in all cases and at the pulmonary end in 18 of 25 cases. The thickness of the separation ranged from 0.4 to 1.3 (0.7+/-0.2) mm at the aortic end and 0.3 to 0.8 (0.6+/-0.2) mm at the pulmonary end. The length of the ductus and of the ampulla had a significant positive correlation with the thickness of the aortic end separation. Apparent endothelial coverage of the coil was completed by 6 months after coil occlusion. Infective endocarditis or thromboembolism is an unlikely complication once endothelium covers the implanted coil.

Aortic input impedance and ventriculoarterial coupling following cardioversion/defibrillation.

Defibrillation shocks are commonly used after cardiac surgery or during defibrillator implantation. The hemodynamic consequences of countershocks on circulatory dynamics are not completely understood, and there is a lack of information concerning the effects on ventriculoarterial interaction. The study presented here was performed to assess the influence of defibrillation shocks on arterial hemodynamics and ventriculoarterial coupling. Eight mongrel dogs (weight 15-18 kg) were anesthetized and median thoracotomy was performed. Pressure in the ascending aorta and the left ventricle and flow in the ascending aorta were continuously monitored. After induction of atrial or ventricular fibrillation, termination was achieved by epicardial low energy shocks (atrium, 3J; ventricle, 51). In an additional attempt ventricular fibrillation was terminated by a high energy shock (34J). Aortic input impedance was calculated by fast-Fourier-transformation of aortic flow and pressure signals, while ventriculoarterial coupling was expressed by the ratio of aortic and ventricular end systolic elastance (Ea/Ees). Defibrillation by low energy shocks of atrial or ventricular fibrillation did not result in changes of the aortic impedance spectrum, and ventriculoarterial coupling remained unaltered compared to control conditions. High energy defibrillation, however, resulted in a marked rise in total peripheral resistance (P < 0.03). The ratio of Ea/Ees increased significantly (P < 0.005). These effects were reversible within 15 minutes. Low energy defibrillation does not alter arterial hemodynamics and ventriculoarterial coupling in this experimental setup. High energy defibrillation, however, results in a temporary increase of ventricular load. This finding may be of particular interest in patients with poor left ventricular function.

Repair of Aortico–Left Ventricular Tunnel Originating From the Left Aortic Sinus

We report on a case of an 11-year-old asymptomatic child with aortico–left ventricular tunnel arising from the left aortic sinus. Preoperative transesophageal echocardiography showed a dilated aortic root with mild aortic valve incompetence and demonstrated the course of the tunnel, which originated from the left coronary sinus entering the outlet portion of the left ventricular outflow tract. Patch closure of the aortic end of the tunnel eliminated left ventricular volume overload with immediate marked reduction of cardiomegaly. At 10-month follow-up the child is asymptomatic and receiving no oral medications. Control two-dimensional Doppler echocardiography shows trivial central aortic valve incompetence.

New-generation valved conduit: An experimental study

Objective: An ideal valved conduit to repair complex congenital heart defects is yet to be developed. In this study we have evaluated the merits of our newly developed calcification-free biologic valve incorporated in a compatible conduit of biologic origin in an animal model. Methods: Porcine aortic valves and main pulmonary arteries were cross-linked in glutaraldehyde, followed by coupling to partially degraded heparin through an intermediate surface-bound substrate containing amino groups. Because commercially available valves are treated only with glutaraldehyde, control aortic valves and main pulmonary arteries were cross-linked in 0.625% glutaraldehyde. Valved conduits were fabricated from main pulmonary arteries, which were sewn to the aortic and ventricular ends of aortic valves. Valved conduits were examined for calcification and other pathologic changes after being implanted in the descending thoracic aorta in juvenile sheep for 5 months. Results: Severe calcification was noticed in all layers of cusps (calcium, 231.86 ± 17.90 mg/gm) and aortic wall (calcium, 123.24 ± 24.72 mg/gm) of aortic valves and main pulmonary arteries (calcium, 135.43 ± 26.63 mg/gm) of valved conduits treated with 0.625% glutaraldehyde. Cusps (calcium, 1.28 ± 0.22 mg/gm) of the aortic valve of heparin-bonded conduits did not calcify at all. Only sparse calcific deposits were noticed in the medial layer of the aortic wall (calcium, 25.90 ± 22.79 mg/gm) of aortic valves and main pulmonary arteries (calcium, 9.64 ± 10.79 mg/gm) of the valved conduits coupled to heparin. Conclusion: Heparin coupling is effective in preventing calcification of glutaraldehyde cross-linked valved conduits implanted in the systemic circulation of juvenile sheep. J Thorac Cardiovasc Surg 1997;114:218-23

Dependence of aortic pulse wave assessments on behavioural state in normal term fetus.

To investigate any influence of behavioural states on the pulse waves in the descending aorta, 21 human fetuses were studied in utero in uncomplicated gestation at the age of 36-41 weeks. The fetal behavioural states were identified using two real-time scanners and one cardiotocograph. The aortic waveform data and pulse wave velocity (PWV) were recorded by means of two double phase-locking echo-trackers. The PWV of the fetal aorta was significantly lower in fetal behavioural state (FBS) 2F than in FBS 1F, when the fetus was apnoeic, and was also reduced in both states during fetal breathing. The calculated pulse pressure showed the same trend as the PWV. The fetal aortic end diastolic diameter and the pulse amplitude did not alter, when the two states changed. Our data suggest that the central haemodynamics in term fetuses are independently influenced by their behavioural state as well as by fetal breathing. The study of pulse waves in the fetal aorta should preferably be performed during apnoea in state 1F, when neither gross body movements nor breathing movements disturb the recording.