Aortic Root Injection Research Articles

Selective Angiographic Flat Detector Computer Tomography Blood Volume Imaging in Pre-Operative Vascular Mapping and Embolization of Hypervascular Intracranial Tumors-Preliminary Clinical Experience.

Pre-operative embolization of hypervascular intracranial tumors can be performed to reduce bleeding complications during resection. Accurate vascular mapping of the tumor is necessary for both the correct indication setting for embolization and for the evaluation of the performed embolization. We prospectively examined the role of whole brain and selective parenchymal blood volume (PBV) flat detector computer tomography perfusion (FD CTP) imaging in pre-operative angiographic mapping and embolization of patients with hypervascular intracranial tumors. Whole brain FD CTP imaging with a contrast injection from the aortic root and selective contrast injection in the dural feeding arteries was performed in five patients referred for tumor resection. Regional relative PBV values were obtained pre- and post-embolization. Total tumor volumes with selective external carotid artery (ECA) supply volumes and post-embolization devascularized tumor volumes were determined as well. In all patients, including four females and one male, with a mean age of 54.2 years (range 44–64 years), the PBV scans were performed without adverse events. The average ECA supply was 54% (range 31.5–91%). The mean embolized tumor volume was 56.5% (range 25–94%). Relative PBV values decreased from 5.75 ± 1.55 before embolization to 2.43 ± 1.70 post-embolization. In one patient, embolization was not performed because of being considered not beneficial for the resection. Angiographic FD CTP imaging of the brain tumor allows 3D identification and quantification of individual tumor feeder arteries. Furthermore, the technique enables monitoring of the efficacy of pre-operative endovascular tumor embolization.

1644 Unusual management of dislodged TAVR prosthesis, Nightmare in Cath lab

Abstract Introduction The Trans aortic valve replacement( TAVR) is well established technique that is basically designed for patient with sever aortic stenosis with high surgical risk. We describe a TAVR procedure was complicated with valve dislodgment and treated without surgical intervention Case report 75 year old Female Patient hypertensive, diabetic, Hypothyroidism and Atrial Fibrillation on oral anticoagulation. Her transthoracic echocardiography(TTE) showed sever critical aortic valve stenosis and calculated aortic valve are was 0.6 cm² and Peak gradient is 68mmhg and mean 46 mmHg , sever Left ventricular dysfunction and estimated EF 25 % . The CT Aortogram showed The aortic annulus maximum transverse diameter measures was 30 mm and the anteroposterior diameter was 25 mm. The sinus of Valsalva measures 37 mm was Sino tubular junction measures 24 mm and the proximal ascending aorta measures 39 mm. There is no evidence of coronary artery disease by the CT coronary angiogram. Because of depressed LV function, it was decided to do the TAVR with ECMO (Extra Corporeal Membrane Oxygenation) support. Based on CT measurements, CoreValve29 was selected The native valve is pre dilated then CoreValve29 was advanced. Unfortunately valve was larger than the aortic annulus and during trial to valve deployment ( Fig A) ,valve jumped into proximal ascending aorta in opining position just few centimeters from coronary ostium ( Fig B). We advance balloon for maximum dilatation of core valve 29 to ensure fixation of valve in ascending aorta and complete opening of valve leaflets. A second smaller valve (coreValve26) was advanced through the dislodged valve and crossing through its leaflet of first core valve (which settled in aorta) and successfully reaches the aortic annulus and confirming proper positioning of the coreValve26 and then deployed safely The coreValve26 was deployed in acceptable position and coreValve29 was hooked and well-fixed to 26 valves in proximal ascending aorta (Fig C). Coronary flow was secured and confirmed by aortic root injection (Fig F). Patient kept supported on ECMO before and during the TAVR procedure. The patient tolerated the procedure and was stable hemodynamically throughout the procedure. Successful ECMO weaning and patient hemodynamically remained stable with Total bypass time on ECMO was 142 minutes. Post procedure chest X ray showed two corValves hooked together in aortic root and ascending aorta in (Fig D). Follow up TTE showed improved EF systolic LV function (EF 39 %). Normal functioning aortic valve prosthesis. Conclusion Up to our knowledge, this is the first case that valve dislodgment was treated percutaneously not required urgent surgical intervention. Although it is one case report, however it could open the ideas for new approach how to manage difficult cases with dislodged valve with percutaneous approach. Abstract 1644 Figure.

Aortic root rupture caused by simultaneous aortic root injection during balloon aortic valvuloplasty in a patient undergoing transcatheter aortic valve implantation.

Aortic root rupture caused by simultaneous aortic root injection during balloon aortic valvuloplasty in a patient undergoing transcatheter aortic valve implantation.

Transthoracic echocardiography is adequate for intraprocedural guidance of transcatheter aortic valve implantation.

BackgroundWhile transcatheter aortic valve implantation (TAVI) has traditionally been supported intraprocedurally by transoesophageal echocardiography (TOE), transthoracic echocardiography (TTE) is increasingly being used. We evaluated echocardiographic imaging characteristics and clinical outcomes in patients who underwent TTE during TAVI (TTE-TAVI).Methods and resultsA select team of dedicated sonographers and interventional echocardiographers performed TTE-TAVI in 278 patients, all of whom underwent TAVI through transfemoral access. We implanted the Medtronic EVOLUT R valve in 258 patients (92.8%). TTE images were acquired immediately pre-procedure by a dedicated sonographer in the cardiac catheterization laboratory with the patient in the supine position. TTE was then performed post deployment of TAVI. In the procedure, TTE image quality was fair or better in 249 (89.6%) cases. Color-flow Doppler was adequate or better in 275 (98.9%) cases. In 2 cases, paravalvular regurgitation (PVL) could not be assessed confidently by echocardiography due to poor image quality; in those cases, PVL was assessed by fluoroscopy, aortic root injection and invasive hemodynamics. Both TTE and invasive hemodynamics were used in the assessment of need for post-deployment stent ballooning (n = 23, 8.3%). TTE adequately recognized new pericardial effusion in 3 cases. No case required TOE conversion for image quality. There was only 1 case of intraprocedural TTE failing to recognize moderate PVL, without clinical implication. In 99% of patients, TTE-TAVI adequately assessed PVL compared with 24-h and 1-month follow-up TTE.ConclusionsWith the current generation of TAVI, TTE-TAVI is adequate intraprocedurally when performed by specialized sonographers and dedicated cardiologists in a highly experienced TAVI center.

Prevalence and characteristics of coronary artery anomalies in children with congenital heart disease diagnosed with coronary angiography.

Aim of the present study was to determine the prevalence of coronary artery anomalies in children with congenital heart disease. Data of 1138 consecutive patients who were referred for cardiac catheterization and angiography for assessment of coronary anomaly between January 2005 and December 2009 were retrospectively analyzed. Total of 515 patients whose coronary arteries could be examined through left ventricle and aortic root injection were included in the study. Of 515 angiograms with visible coronaries, 42 patients (20 males, 22 females; mean age: 5.3±2.0 years) were found to have final diagnosis of coronary anomaly. Prevalence of coronary artery anomalies was 8.16% in this study. It was determined that 38 (90.4%) were anomalies of origination, 2 (4.8%) were anomalies of intrinsic coronary arterial anatomy, and 2 (4.8%) were anomalies of coronary termination. Most common coronary artery abnormality was anomalous origin of the right coronary artery from the left aortic sinus (16 patients; 38.1%), and the most common congenital heart disease was tetralogy of Fallot (18 patients; 42.9%). Recognizing variability of coronary artery anomalies is critical when considering surgical or interventional therapies in children with congenital heart disease.

A rare indication for surgery in acute myocardial infarction: spontaneous aortic thrombus causing left main stem occlusion

A 52-year old man presented with acute anterolateral ST elevation myocardial infarction. At angiography, the left coronary artery was not found. Aortic root injection revealed a large filling defect (Fig. 1A). Emergency surgery identified an adherent aortic mass extending into the left coronary artery (Fig. 1B and C). The macroscopic appearance suggested a tumour (Fig. 1D); however, histology demonstrated only an organized thrombus, apparently spontaneous.

Bentall procedure for adult patient with supravalvular aortic stenosis and coronary aneurysms

We report a complex case of a 35-year-old gentleman who presented with large anterior myocardial infarction. Coronary angiography showed multiple coronary aneurysms of all proximal major coronaries with a total occlusion of the LAD artery. A diffuse form of supravalvular aortic stenosis was discovered incidentally upon aortic root injection and was confirmed with CT aortogram. Echocardiography revealed akinesia of the anterior wall with preserved thickness and depressed left ventricular function (EF = 25%). Aortic valve was competent with normal leaflet structure. The patient underwent Bentall procedure with LIMA to LAD coronary bypass grafting with the use of cardiopulmonary bypass utilizing the right axillary artery for arterial cannulation and routine right atrial venous cannulation. The post-operative course was uneventful. The patient was discharged home after 7 days and came back for follow up after 6 months in good condition.

Left Coronary Artery Occlusion After Percutaneous Pulmonary Valve Implantation

Percutaneous pulmonary valve implantation (PPVI) is an attractive option for patients with pulmonary valve insufficiency or stenotic right ventricular outflow tracts. We present the case of a 26-year-old patient in which PPVI was used to treat d-transposition of the great arteries, uncommon coronary artery anatomy, and conduit stenosis that resulted from multiple operations on the right outflow. Days after discharge to home, she experienced acute chest discomfort correlating with ischemia noted on an electrocardiogram and elevated troponin levels. Coronary angiography confirmed mechanical compression of the left anterior descending coronary artery. The valve was removed in an emergency operation and replaced with a biological conduit.

Optimization of acquisition and contrast injection protocol for C-arm CT imaging in transcatheter aortic valve implantation: initial experience in a swine model

To determine the optimal C-arm computed tomography (CT) protocol for transcatheter aortic valve implantation (TAVI) in swine. In 6 swine, C-arm CT was performed using 5-s ungated acquisition during sinus rhythm with aortic root (Method 1) or peripheral (Method 2) injection, and during rapid ventricular pacing with root injection (Method 3). Additionally, 24-s ECG-gated acquisitions were performed during sinus rhythm with root (Method 4) or peripheral (Method 5) injection. Aortic root enhancement, presence of artifacts and contrast volumes were compared for all methods. Aortic root measurements were also compared between C-arm CT and multidetector-row computed tomography (MDCT). The best C-arm CT image set was identified and used to predict optimal angiographic projection angles during TAVI; predictions were compared to those from MDCT. Methods 1, 3, 4, and 5 yielded sufficient root enhancement with mild or moderate artifacts and aortic annulus, sinotubular junction, and mid-ascending aorta diameters similar to MDCT. Ungated C-arm CT (Methods 1, 3) required less contrast than ECG-gated C-arm CT (Methods 4, 5). Method 3 was optimal yielding images with high attenuation, few artifacts (2.0), and root measurements similar to MDCT using minimal contrast (36 mL). Predicted angiographic projections from Method 3 were similar to MDCT. Ungated C-arm CT during rapid pacing with aortic root injection required minimal contrast, yielded high attenuation and few artifacts, and aortic root measurements and predicted angiographic planes similar to those from MDCT.

Angiographic evaluation of the coronary artery anatomy in patients with hypoplastic left heart syndrome

Evaluation of coronary anatomy in survivors of staged palliation for hypoplastic left heart syndrome might be capable of identifying anomalies and morphologic changes of the coronary arteries that may have implications for outcome. We reviewed coronary angiograms obtained by native aortic root injection of 84 patients (mitral atresia/aortic atresia, n = 39; mitral stenosis/aortic stenosis, n = 25; mitral stenosis/aortic atresia (MS/AA), n = 13 and mitral atresia/aortic stenosis, n = 7). Epicardial course, anomalies, coronary dominance and native ascending aorta dimensions were analysed. Right dominance was present in 51%, left in 37% and balanced type in 12%. Dominance was unrelated to anatomic subtypes (P = 0.16). Ventriculocoronary connections (VCCs) were found in 15 (18%) and tortuosity was seen in 28 (33%) patients. Both occurred more often with MS/AA (tortuosity: 12 of 13 patients, P < 0.001; VCCs: 6 of 13 patients, P = 0.001). Collaterals to extra-cardiac vessels were visualized in 41 (49%) patients. Native ascending aorta dimensions were smaller with aortic atresia [40 (18-107) vs. 127 (32-328) mm(2)/m(2), P < 0.001]. In 18 patients with a relatively large native aorta [106 (36-328) vs. 44 (18-248) mm(2)/m(2), P < 0.001] retention of contrast in the aortic root identified areas of low blood flow. Left coronary dominance was more prevalent compared with the normal population. The impact of observed anomalies is unclear. Most VCCs are small and probably have no impact on coronary perfusion. Native ascending aorta dimensions were larger in patients with aortic stenosis. Larger aortic roots may predispose to thrombus formation and effective anticoagulation might be considered.

Long-Term Cardiac-Targeted RNA Interference for the Treatment of Heart Failure Restores Cardiac Function and Reduces Pathological Hypertrophy

RNA interference (RNAi) has the potential to be a novel therapeutic strategy in diverse areas of medicine. Here, we report on targeted RNAi for the treatment of heart failure, an important disorder in humans that results from multiple causes. Successful treatment of heart failure is demonstrated in a rat model of transaortic banding by RNAi targeting of phospholamban, a key regulator of cardiac Ca(2+) homeostasis. Whereas gene therapy rests on recombinant protein expression as its basic principle, RNAi therapy uses regulatory RNAs to achieve its effect. We describe structural requirements to obtain high RNAi activity from adenoviral and adeno-associated virus (AAV9) vectors and show that an adenoviral short hairpin RNA vector (AdV-shRNA) silenced phospholamban in cardiomyocytes (primary neonatal rat cardiomyocytes) and improved hemodynamics in heart-failure rats 1 month after aortic root injection. For simplified long-term therapy, we developed a dimeric cardiotropic adeno-associated virus vector (rAAV9-shPLB) to deliver RNAi activity to the heart via intravenous injection. Cardiac phospholamban protein was reduced to 25%, and suppression of sacroplasmic reticulum Ca(2+) ATPase in the HF groups was rescued. In contrast to traditional vectors, rAAV9 showed high affinity for myocardium but low affinity for liver and other organs. rAAV9-shPLB therapy restored diastolic (left ventricular end-diastolic pressure, dp/dt(min), and tau) and systolic (fractional shortening) functional parameters to normal ranges. The massive cardiac dilation was normalized, and cardiac hypertrophy, cardiomyocyte diameter, and cardiac fibrosis were reduced significantly. Importantly, no evidence was found of microRNA deregulation or hepatotoxicity during these RNAi therapies. Our data show for the first time the high efficacy of an RNAi therapeutic strategy in a cardiac disease.

Interventional Electrophysiology in Patients With Congenital Heart Disease

“The treatment of congenital heart disease is unsatisfactory. As a rule, nothing can be done to improve patients symptomatically; in some instances digitalis may be of help.” — —L. Emmett Holt, MD, 1933 On August 26, 1938, Dr Robert Gross performed the first successful surgery for a congenital heart defect by closing a patent ductus arteriosus in a 7-year-old girl. The event marked the beginning of an interventional approach to congenital heart disease (CHD) that forever banished the sort of pessimism expressed by Dr Holt in his classic pediatric textbook only 5 years earlier.1 Subsequent diagnostic and operative innovations ultimately led to surgical solutions for nearly all anatomic heart defects, allowing the vast majority of infants born with CHD in the modern era to survive into adulthood. However, improved hemodynamic longevity has exposed alternate sources of morbidity and mortality for this population, central among which are cardiac rhythm disorders. In some instances, arrhythmias are intrinsic to the CHD lesion itself, but in most cases, they arise as an unintended consequence of prior corrective surgery whenever patches and suture lines function in conjunction with hypertrophy and fibrosis to create the substrate for reentrant tachycardias. It is fortunate that improved understanding of rhythm abnormalities in CHD has coincided with the emergence of interventional electrophysiological techniques. Catheter ablation, arrhythmia surgery, pacemakers, and implantable defibrillators have now become indispensable treatment options for this group. It is the purpose of this article to review the application of these tools to CHD with an emphasis on unique technical challenges. Congenital heart defects occur in roughly 0.8% of live births, and in 30% to 50% of cases, the malformations are severe enough to warrant ≥1 surgical procedures during early childhood.2 Arrhythmia mechanisms vary according to the underlying anatomic defect and method of surgical repair. The …

Catheter contrast-enhanced coronary CT-angiography using an aortic root injection- preliminary technical development in four patients

The feasibility of performing coronary computed tomographic angiography (CTA) with an intra-aortic injection of iodinated contrast was tested in four patients immediately following diagnostic cardiac catheterization and placement of a 6-french pigtail catheter into the aortic root. A diluted contrast mixture [75 cc Omnipaque 350 mixed with 125 cc normal saline (4-slice scanner) vs. 40 cc Omnipaque 350 mixed with 60 cc normal saline (16-slice scanner)] was injected at a rate of 6 to 7.7 cc/sec at the onset of breath-hold and helical (4 slice, n=3, and 16-slice, n=1) retrospective ECG-triggered acquisition. The proximal and distal coronary vasculature including small tributaries were depicted with high signal-to-noise (S/N) and free from underlying blood pool enhancement. The right coronary artery was sub optimally enhanced in two patients. No significant disease was found on CTA or XRA in two patients; however, severe multivessel disease was demonstrated on both modalities in two patients. Catheter contrast-enhanced coronary CTA is feasible utilizing low injection rates and low iodinated contrast volumes, however, catheter modifications are required for consistent and homogeneous opacification of the aortic root.

First selective coronary arteriogram.

To the Editor: I enjoyed reading Dr Ryan’s superb recount of the historical development of coronary arteriography,1 but I wish to make a comment on its chronology. Dr F. Mason Sones, Jr, of the Cleveland Clinic performed the first selective coronary arteriogram on October 30, 1958.2 The selective right coronary arteriogram photographed by Sones on October 30, 1958, was inadvertently obtained during an aortic root injection in a 26-year-old patient with rheumatic heart disease,3 when the catheter whiplashed into the ostium of the right coronary artery. Although the performance of this selective coronary arteriogram was unintentional, it was the first direct injection of a contrast agent into a coronary artery (Figure). Cine frame from the first selective coronary arteriogram recorded by F. Mason Sones, Jr, on October 30, 1958. …

A Novel Technique While on Extracorporeal Membrane Oxygenation to Rule Out Anomalous Left Coronary Artery

The authors present an infant who required extracorporeal membrane oxygenation (ECMO) for treatment of cardiac failure. Echocardiography could not conclusively demonstrate the origin of the left coronary artery. To rule out anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) as the etiology of the cardiac failure, angiography was deemed necessary. Given the logistic issues involved in moving a patient to the cardiac catheterization suite while receiving ECMO, a method was developed to allow for aortic root injection while on ECMO. The technique involved momentary cessation of ECMO flow to the patient and clamping of the arterial and venous lines followed by injection into the aortic inflow cannula. A chest x-ray demonstrated adequate filling of the aortic arch and adequate visualization of the left coronary artery. While other therapeutic procedures and diagnostic studies have been performed during ECMO, the authors report for the first time a novel technique to allow for aortic arch/coronary artery angiography and provide definitive delineation of the coronary artery anatomy to rule out ALCAPA.

ANOMALOUS CORONARY ARTERIES OF AORTIC ORIGIN

SUMMARYAnomalous coronary arteries cause only uncharacteristic symptoms and are therefore often an incidental finding during conventional coronary angiography, with an incidence of 0.3‐0.8%. The commonest anomaly is an aberrant origin of the main left or right coronary artery from the wrong sinus of Valsalva. Rarely there is a fistula draining into one of the cardiac cavities (right ventricle, right atrium, left ventricle or, rarely, superior vena cava) or displaced connection, as seen in anomalous origin of coronary artery from the pulmonary artery, resulting in a left‐to‐right shunt. In congenital heart disease, especially Fallot's tetralogy, the incidence of abnormal coronary arteries may be 2% or more. The proximal course in the former category may be misdiagnosed in up to 50% of cases. Aortic root injection with subtraction angiography, further detailed investigation with transoesophageal echocardiography or magnetic resonance angiography are therefore required as these have potential implications on subsequent surgery. Because of the abnormal course between aorta and pulmonary artery/outflow tract of the right ventricle and acute angulation there is a risk of angina, acute myocardial infarction or sudden death during or after exercise. It is therefore important to identify the exact cardiac anatomy, particularly in patients undergoing angioplasty, stenting or cardiac surgery. (Int J Clin Pract 2000; 54(6): 390‐394)

Expression of coxsackie adenovirus receptor and alphav-integrin does not correlate with adenovector targeting in vivo indicating anatomical vector barriers.

Recombinant adenoviral vectors are broadly applied in gene therapy protocols. However, adenovector-mediated gene transfer has limitations in vivo. One of these is the low gene transfer rate into organs other than the liver after systemic intravenous vector injection. Local direct injection into the target organ has been used as one possible solution, but increases necessary equipment and methodology and is traumatic to the target. Wild-type adenovirus infection as well as adenovector-mediated gene transfer depends on virus interaction with the Coxsackie adenovirus receptor (CAR) mediating virus attachment to the cell surface, and on interaction with alphavbeta3 and alphavbeta5 integrins mediating virus entry into the cell. In order to assess the receptor-associated potential of different tissues to act as adenovector targets, we have therefore determined CAR and alphav-integrin expression in multiple organs from different species. In addition, we have newly determined several human, rat, pig and dog CAR-mRNA sequences. Sequence comparison and structural analyses of known and of newly determined sequences suggests a potential adenovirus binding site between amino acids 29 and 128 of the CAR. With respect to the virus receptor expression patterns we found that CAR-mRNA expression was extremely variable between different tissues, with the highest levels in the liver, whereas alphav-integrin expression was far more homogenous among different organs. Both CAR and alphav-integrin showed similar expression patterns among different species. There was no correlation, however, between the adenovector expression patterns after intravenous, intracardiac and aortic root injection, respectively, and the virus receptor patterns. In summary, many organs carry both receptors required to make them potential adenovector targets. In sharp contrast, their actual targeting clearly indicates that adenovirus receptor expression is necessary but not sufficient for vector transfer after systemic injection. The apparently very important role of anatomical barriers, in particular the endothelium, requires close attention when developing non-traumatic, organ-specific gene therapy protocols.

Importance of neurokinin-1 receptors in the nucleus tractus solitarii of mice for the integration of cardiac vagal inputs.

Unmyelinated vagal afferents from the heart terminate within the nucleus tractus solitarii (NTS) located in the dorsomedial medulla. The neurotransmitter and postsynaptic receptors mediating information from cardiac vagal receptors to the NTS are unknown. This study determined the effects of neurokinin-1 (NK1) receptor blockade on: (i) the reflex response evoked following aortic root injection of either veratridine (1-3 microg/kg) or bradykinin (80-300 ng/kg) to stimulate cardiac receptors in in vivo anaesthetized mice; and (ii) the evoked synaptic response of cardioreceptive NTS neurons following both intraleft-ventricular injection of veratridine or bradykinin, and electrical stimulation of the ipsilateral vagus nerve in an arterially perfused working heart-brainstem preparation of mouse. Administration of CP-99,994 (0.75-1.5 mg/kg i.v.), a specific NK1 antagonist, attenuated significantly the evoked reflex bradycardia and depressor response following cardiac receptor (n = 6), but not pulmonary chemoreflex stimulation in vivo. From extracellular recordings of cardioreceptive NTS neurons, CP-99,994 reduced reversibly the total number of evoked spikes, peak firing frequency and response duration evoked by intraventricular injections of veratridine (n = 5) or bradykinin (n = 5). The number of evoked action potentials following electrical stimulation of the vagus nerve was also reduced. In five whole cell recordings of NTS neurons, both the evoked depolarization following cardiac receptor stimulation, and the peak amplitude and duration of vagus nerve-evoked EPSPs were reduced by CP-99,994; synaptic inputs from both peripheral chemoreceptors or pulmonary C-fibres were unaffected. These data support a selective involvement of NK1 receptors in the transmission of cardiac vagal afferent inputs to NTS neurons integrating cardiorespiratory information.

Convergence properties of solitary tract neurons responsive to cardiac receptor stimulation in the anesthetized cat.

The convergence pattern of cardiac receptors, pulmonary C-fibers, carotid chemoreceptor, and baroreceptor afferents onto neurons within the nucleus of the solitary tract (NTS) was studied in the anesthetized (pentobarbitone sodium, 40 mg/kg,) paralyzed and artificially ventilated cat. Extra- and intracellular recordings were made from NTS neurons while stimulating both cardiac receptors by aortic root injections of veratridine (1-3 micrograms/kg) and pulmonary C-fibers by a right atrial injection of phenylbiguanide (10-20 micrograms/kg). The ipsilateral carotid body was stimulated by using arterial injection of CO2-saturated bicarbonate solution, whereas inflation of the ipsilateral carotid sinus was used to activate baroreceptors. The ipsilateral cardiac vagal branch, cervical vagus, and carotid sinus nerves were stimulated electrically (1 Hz, 0.2-1 ms, 1-35 V). In 78 NTS neurons recorded either extracellularly (n = 47) or intracellularly (n = 31), electrical stimulation of the cardiac branch of the vagus nerve evoked synaptic potentials (spikes and/or excitatory postsynaptic potentials) with an onset latency between 4 and 220 ms. Some neurons displayed both short and long latency inputs(15.5 +/- 1.8 and 160.0 +/- 8.5 ms; n = 14). Of these 78 neurons, 24 responded to veratridine stimulation of cardiac receptors (i.e., cardioreceptive neurons) by exhibiting an augmenting-decrementing discharge of 37 +/- 4 s in duration with a peak frequency of 30 +/- 5 Hz. Convergence from other cardiorespiratory receptors was noted involving either carotid chemoreceptors (n = 7) or pulmonary C-fibers (n = 4) or from both carotid chemoreceptors and pulmonary C-fibers (n = 6). In contrast, only one cardioreceptive NTS neuron was activated by distension of the carotid sinus. Recording sites recovered were confined to the medial NTS at the level of the area postrema and extended caudally into the commissural subnucleus. Our results indicate a convergence of carotid chemoreceptor and pulmonary C-fiber afferent inputs to cardioreceptive NTS neurons. With the paucity of baroreceptor inputs to these neurons it is suggested that sensory integration within the NTS may reflect regulatory versus defensive or protective reflex control.

Combination of Dobutamine and Myocardial Contrast Echocardiography to Differentiate Postischemic From Infarcted Myocardium

Objectives. This study tested whether the combination of dobutamine echocardiography (DE) and myocardial contrast echocardiography (MCE) was superior to either technique alone in identifying postischemic myocardium and in differentiating it from necrotic myocardium.Background. Wall motion abnormalities at rest occur in postischemic myocardium in the presence of infarction, stunning or hibernation, alone or in combination. Various investigators have suggested that either DE or MCE can be used to identify the presence of myocardial viability.Methods. We studied a total of 53 mongrel dogs in an open chest model of coronary occlusion of various durations followed by reperfusion and dobutamine administration (10 μg/kg body weight per min). MCE with aortic root injections of Albunex (area under the curve) and DE (percent thickening fraction) were performed at the different stages. Postmortem triphenyltetrazolium chloride (TTC) staining was used to identify myocardial necrosis.Results. Thirteen dogs underwent brief (15 min) occlusions and developed no necrosis (Group I). Of 40 dogs that underwent prolonged (30 to 360 min) occlusions, 14 had no infarction (Group II), whereas 26 did (Group III: 12 papillary muscle, 7 subendocardial, 7 transmural). MCE (expressed as percent change from baseline) demonstrated changes that paralleled the blood flow changes observed by radiolabeled microspheres at all interventions (r = 0.67, p < 0.0001). Regional ventricular function improved with dobutamine administration in the ischemic region in all three groups. The sensitivity (88%) for detecting myocardial viability was superior when the two techniques were combined; however, a poor specificity (61%) was observed.Conclusions. Contractile reserve and perfusion data are complementary when assessing regional wall motion abnormalities in postischemic myocardium. DE alone cannot differentiate postischemic from infarcted myocardium; simultaneous data on myocardial perfusion are required. The combination of DE and MCE is superior to either technique alone for identifying the absence of myocardial necrosis.(J Am Coll Cardiol 1997;29:974–84)© 1997 by the American College of Cardiology