Echocardiographic characteristics and causal mechanism of physiologic mitral regurgitation in young normal subjects

BACKGROUND

It has become evident that mitral regurgitation (MR) is not uncommon in healthy subjects, and Doppler color flow mapping is a technique that imparts important information relevant to its detection.

HYPOTHESIS

Using transthoracic echocardiography, this study evaluated the mechanism of physiologic MR in young normal subjects using transthoracic echocardiography.

METHODS

The study population consisted of 48 young normal subjects (mean 21 +/- 5 years) with MR (physiologic MR group), 40 age-matched young normal subjects (mean 20 +/- 5 years) without MR (control group), 45 patients (mean 41 +/- 15 years) with mitral valve prolapse with MR (MVP group), and 27 patients (mean 59 +/- 13 years) with ruptured chordae tendineae (rupture group).

RESULTS

Men were predominant in the rupture group, whereas there were no significant gender differences in the other three groups. Left ventricular end-diastolic dimension and left atrial systolic dimension were slightly smaller in the physiologic MR group than in the control group, but were significantly smaller than those in the MVP and rupture groups. The ratio of the maximum anteroposterior diameter to the maximum transverse diameter on chest radiography and the ratio of the short- to long-axis diameter of the left ventricular cavity at end diastole, determined from two-dimensional short-axis echocardiogram, were significantly lower in the physiologic MR group than in the other three groups. Mitral regurgitation occurred more frequently at the posteromedial commissural site in the physiologic MR and MVP groups, whereas there was no preference for location in the rupture group. Early systolic MR was often observed in the physiologic MR group, whereas pansystolic MR was common in the MVP and rupture groups.

CONCLUSION

As a causal mechanism for physiologic MR detected in young normal subjects, "flattening" of the thorax during growth may cause morphologic abnormalities of the left atrial and ventricular cavities, resulting in spatial imbalance of the mitral complex and resulting in malcoaptation of the valve.

[Studies of three-dimensional cardiac late gadolinium enhancement MRI at 3.0 Tesla]

Cardiac late Gadolinium enhancement MR imaging has been shown to allow assessment of myocardial viability in patients with ischemic heart disease. The current standard approach is a 3D inversion recovery sequence at 1.5 Tesla. The aims of this study were to evaluate the technique feasibility and clinical utility of MR viability imaging at 3.0 Tesla in patients with myocardial infarction and cardiomyopathy. In phantom and volunteer studies, the inversion time required to suppress the signal of interests and tissues was prolonged at 3.0 Tesla. In the clinical study, the average inversion time to suppress the signal of myocardium at 3.0 Tesla with respect to MR viability imaging at 1.5 Tesla was at 15 min after the administration of contrast agent (304.0+/-29.2 at 3.0 Tesla vs. 283.9+/-20.9 at 1.5 Tesla). The contrast between infarction and viable myocardium was equal at both field strengths (4.06+/-1.30 at 3.0 Tesla vs. 4.42+/-1.85 at 1.5 Tesla). Even at this early stage, MR viability imaging at 3.0 Tesla provides high quality images in patients with myocardial infarction. The inversion time is significantly prolonged at 3.0 Tesla. The contrast between infarction and viable myocardium at 3.0 Tesla are equal to 1.5 Tesla. Further investigation is needed for this technical improvement, for clinical evaluation, and for limitations.

[Studies of free breathing three-dimensional heart delayed enhancement MRI under resting respiration using KING]

Heart delayed enhancement magnetic resonance imaging(MRI)is an attempt to obtain intense image contrast using the null-point of normal myocardium, which changes with time. Imaging is generally conducted under breath-hold, but, if the retrospective gating method is used, it is necessary to shorten the imaging time and to fill the center of the k-space with the data in the early phase of imaging. In the present study, we examined free breathing three-dimensional heart delayed enhancement MRI(3D/KING method)using k-space inspired navigator gating(KING). In the 3D/KING, since respiratory artifact decreases by combining with the fat suppression technique and the gating window can be set widely, the imaging time was shortened in comparison with the conventional 3D method. In 3D/KING/isotropic(iso), on the other hand, the respiratory artifact was decreased by transverse imaging. The mean end time of imaging by the 3D/KING method(n=10)and the 3D/KING/iso(n=5)was 3.05+/-0.69 and 4.59+/-0.74 minutes, respectively. Moreover, the signal intensity ratio(SIR)of abnormal myocardium versus normal myocardium in the 3D/KING method was low in comparison with that in the breath-hold method. However, the capability to detect lesions was similar, and good images were obtained from the patients showing poor breath-hold. In the 3D/KING/iso, heart delayed enhancement MRI from multiple directions could be conducted in a single imaging by using the image reconstitution method.

Arterial reconstruction in Buerger's disease: by-pass to disease-free collaterals

BACKGROUND

Arterial reconstructions for ischemia in patients with Buerger's disease are technically challenging. This retrospective review was conducted to identify the critical factor for a successful outcome in bypass surgery for Buerger's disease.

METHODS

DESIGN OF STUDY

retrospective review.

SETTING

University hospital, hospitalized patients.

PATIENTS

since 1993, we performed 10 arterial reconstructions in 8 patients with Buerger's disease. There were 8 tibial artery bypasses and 2 collateral artery bypasses. One bypass was performed in the upper extremity.

INTERVENTIONS

bypass surgery with autogenous vein graft.

MAIN OUTCOMES MEASUREMENTS

graft patency.

RESULTS

Over a mean follow-up period of 41.8 months, there were 3 graft occlusions. Of these, 2 were of bypasses to a patent but diseased tibial artery. One graft was occluded due to a toe stenosis which had been previously detected. The 2 collateral artery bypasses were patent at the last follow-up.

CONCLUSIONS

In Buerger's disease, distal arterial reconstruction is frequently necessary to prevent ischemic limb loss. Collateral artery bypass is an option when the main arteries are affected by the disease. A patent but diseased artery should be avoided as a target for reconstruction.

Staged vascular reconstruction along with repeatedly performed angiography to prevent ischemic limb loss with Buerger's disease: report of a case

An aggressive approach to vascular reconstruction should be adopted in patients with Buerger's disease and peripheral ischemia who are often young and otherwise active. A patient with severe Buerger's disease is reported who was treated successfully by complete vascular reconstruction with staged bypass surgery while also performing repeated angiography to preserve the foot function. A 48-year-old man with Buerger's disease presented with necrosis of the foot. Angiography showed occlusion of the right distal external iliac artery and no runoff below the knee. Repeated angiography after performing a lumbar sympathectomy demonstrated patency of the distal portion of the deep femoral artery. Angiography was again performed after a reconstruction of the deep femoral artery and patency of the anterior tibial artery was observed. A staged bypass operation on the tibial artery was therefore able to achieve a prompt healing of both the toe ulcers and plantar wound.

Inflammatory solitary iliac artery aneurysms: a report of two cases

Inflammatory abdominal aortic aneurysms are associated with atherosclerosis, which are characterized by specific clinical manifestation. We treated two patients with unilateral solitary iliac artery aneurysms with perianeurysmal fibrosis which compressed the ureter resulting in ipsilateral hydronephrosis. After the iliac artery aneurysm was repaired with a prosthetic graft, the hydronephrosis resolved. Microscopically, there was clear evidence of atherosclerosis in one case. There was a characteristic inflammatory reaction around the adventitia in both aneurysms. Localized iliac perianeurysmal fibrosis has not been particularly described. The clinicopathologic similarities between these cases and inflammatory abdominal aortic aneurysms suggest the same pathogenesis.

Identification of the critical spinal arteries with F wave-polysynaptic response complex monitoring: an experimental study

PURPOSE

The main cause of paraplegia after surgery for descending thoracic aortic aneurysms and thoracoabdominal aortic aneurysms is spinal cord ischemia caused by ligation of the critical spinal arteries that are associated with the great radicular artery (GRA). In this experimental study, we attempted to identify the critical spinal arteries with F wave-polysynaptic response complex (FPC) monitoring. The FPC, which we are using as a monitor of spinal cord ischemia, is myogenic potentials evoked by the tibial nerve stimulation through the anterior horn cells.

METHOD

In 18 rabbits, infrarenal lumbar arteries were clamped until there was an FPC amplitude reduction (FPCAR) of at least 60%. The rabbits were classified according to the number of arteries clamped to produce the FPCAR (group A, 1 artery; group B, 2 arteries; group C, 3 arteries). Selective angiography of each lumbar artery was performed in all rabbits.

RESULTS

An FPCAR was observed in all 18 rabbits. In all nine rabbits in group A, the FPCAR was caused by the clamping of one particular lumbar artery. The GRA was shown by means of selective angiography to originate directly from this lumbar artery. In the nine rabbits in groups B and C, 11 FPCARs were observed. Of these, nine FPCARs in nine rabbits were caused by the clamping of lumbar arteries that included the vessel from which the GRA originated.

CONCLUSION

Temporary clamping of lumbar arteries with FPC monitoring can be used as a means of detecting the critical spinal arteries from which the GRA originates.

Kindling of the midbrain periaqueductal gray in rats

We investigated the role of midbrain periaqueductal gray matter (PAG) in the manifestation of generalized seizures by administering electrical stimulation to this area in rats. Electrical stimulation of 60 Hz biphasic square pulses of a 1-s duration administered to the PAG-induced convulsive responses in the following order: (1) Type I, running (stimulus intensity; range 50--200 microA, mean 73.1 microA) without afterdischarge (AD), (2) Type IIa, running (stimulus intensity; range 50--300 microA, mean 111.8 microA) with AD at the PAG and the amygdala (AMY), and (3) Type IIb, generalized tonic--clonic seizures (GTCS) (stimulus intensity; range 50--250 microA, mean 182.1 microA) with AD at the PAG and AMY. Twenty daily PAG stimulations at the non-GTCS inducing threshold failed to produce kindling. However, 20 daily PAG stimulations at the GTCS threshold produced progressive AD spread involving the motor cortex, and progressive changes in the behavioral seizure pattern. These findings indicate that the PAG can be effectively kindled. However, PAG kindling has no apparent influence on subsequent AMY kindling.

HET0016, a potent and selective inhibitor of 20-HETE synthesizing enzyme

The present study examined the inhibitory effects of N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016) on the renal metabolism of arachidonic acid by cytochrome P450 (CYP) enzymes. HET0016 exhibited a high degree of selectivity in inhibiting the formation of 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) in rat renal microsomes. The IC(50) value averaged 35+/-4 nM, whereas the IC(50) value for inhibition of the formation of epoxyeicosatrienoic acids by HET0016 averaged 2800+/-300 nM. In human renal microsomes, HET0016 potently inhibited the formation of 20-HETE with an IC(50) value of 8.9+/-2.7 nM. Higher concentrations of HET0016 also inhibited the CYP2C9, CYP2D6 and CYP3A4-catalysed substrates oxidation with IC(50) values of 3300, 83,900 and 71,000 nM. The IC(50) value for HET0016 on cyclo-oxygenase activity was 2300 nM. These results indicate that HET0016 is a potent and selective inhibitor of CYP enzymes responsible for the formation of 20-HETE in man and rat.

Causes of late mortality in patients with disabling intermittent claudication

The long-term prognosis of patients suffering from intermittent ischemic claudication is reportedly worse than that of the normal population. The outcome of patients with ischemic claudication admitted to hospital was reviewed retrospectively to identify the causes of late death. The cumulative survival rates for patients with claudication were 94.6% at 1 year, 79.4% at 3 years, 67.3% at 5 years and 37.4% at 10 years. The 3 major causes of death, that is, ischemic heart disease, malignancy, and cerebrovascular accident, were equally common. The younger patients tended to die of ischemic heart disease, whereas the older patients died of cerebrovascular accidents. Malignancies caused a similar number of late deaths in all age groups. These results suggest that specific care should be given to patients with intermittent claudication based on the age-related causes of death.

Convulsive seizures induced by N-methyl-D-aspartate microinjection into the mesencephalic reticular formation in rats

Effects of microinjections of a single 2 or 10 nmol dose of N-methyl-D-aspartate (NMDA) into the unilateral mesencephalic reticular formation (MRF) on behavior and electroencephalogram were examined in rats (n=18) during a 15 min period (Exp. 1), and subsequent effects of sound stimulation with key jingling applied at 15, 30, and 45 min after the injections were observed (Exp. 2). The microinjections of 2 nmol dose of NMDA (n=10) induced hyperactivity (9 of 10 rats) and running/circling (8 of 10 rats) in Exp. 1, and hyperactivity (3 of 10 rats) in Exp. 2. Moreover, the microinjections of 10 nmol dose of NMDA (n=8) induced not only hyperactivity (8 of 8 rats) and running/circling (7 of 8 rats) but also generalized tonic-clonic seizures (GTCS) (5 of 8 rats) in Exp. 1; these seizure patterns were also elicited by sound stimulation in Exp. 2. The seizure patterns were accompanied by electroencephalographic seizure discharges in the MRF and the motor cortex. In contrast, the control group rats (n=10) which received a single dose of saline microinjection into the unilateral MRF showed no behavioral or electroencephalographic changes in both Exp. 1 and 2. These findings suggest that the MRF has an important role in the development of GTCS, which follows hyperactivity and running/circling, and that potentiation of excitatory neurotransmission in the MRF participates in the development of audiogenic seizures as well as GTCS.

Anomalies of inferior vena cava and left renal vein: risks in aortic surgery

Although most aortic surgery is now routinely performed without incident, major venous anomalies can cause unexpected bleeding. In the last 6 years, 4 of 166 patients undergoing abdominal aortic surgery at our institution were found to have a major venous anomaly, including a double inferior vena cava (2), a preaortic iliac vein confluence (1), and a circumaortic renal collar (1). The 3 men and 1 woman had a mean age of 62.3 years (range, 56 to 68 years). All four patients underwent surgery for an abdominal aortic aneurysm. Preoperative imaging revealed all of the venous anomalies except for the renal collar. Unexpected venous injuries complicated the operation in one patient who had a double inferior vena cava and an inflammatory abdominal aortic aneurysm and in the patient with the circumaortic renal collar. Major venous anomalies are rarely encountered in patients undergoing aortic surgery. Preoperative assessment and intraoperative awareness are important to prevent unexpected venous injuries. Patients with an anomaly of the left renal vein and an inflammatory abdominal aortic aneurysm are at a particularly high risk.

Dendritic translocation of the rat ferritin H chain mRNA

To elucidate the mechanism regulating the selective transport of mRNAs to synaptic sites, we compared the synaptosomal mRNAs with those from the forebrain using the differential display method. The ferritin H chain mRNA was found to be highly enriched in the synaptosomes. In situ hybridization for the ferritin H chain mRNA in the cultured dissociated neurons and in the hippocampal brain slices demonstrated its existence in the dendritic region. These data clearly indicate the selective translocation of the ferritin H chain mRNA into the dendrites and suggested the local expression of ferritin at the synapse.

Rupture of infected pseudoaneurysms in patients with implantable ports for intra-arterial infusion chemotherapy

Intra-arterial hepatic chemotherapy via implantable reservoirs is being used increasingly. In our department, five patients have undergone emergency surgery since 1991 because of rupture of an infected pseudo-aneurysm at the site of entry of the catheter. Surgical procedures included removal of the catheter and the reservoir, and closure of the affected artery with or without reconstruction. Of these patients, three (60%) died from uncontrollable sepsis. The poor prognosis emphasizes the need, in patients with carcinoma, for strict aseptic technique and hemostasis at the time of catheter placement, and for careful device maintenance.

Simultaneous repair of arch and abdominal aortic aneurysms. A simple new technique using a temporary bypass graft

OBJECTIVE

Atherosclerotic aneurysms in the aortic arch are associated with abdominal aortic aneurysms in up to 37% of cases. We have developed a single-stage approach to the repair of both aneurysms using a temporary bypass.

SUBJECTS

Since November 1996, 5 patients underwent simultaneous repair of aneurysms in the aortic arch and in the infrarenal abdominal aorta, using a new temporary bypass graft technique. Entire arch replacement with simultaneous abdominal aortic aneurysmectomy was performed in one patient. The other 4 patients underwent distal hemi-arch replacement distal from the orifice of the brachiocephalic artery with simultaneous repair of the abdominal aortic aneurysm.

METHOD

For the entire arch replacement procedure, blood flow to all major branches of the aortic arch was established using a bifurcated graft. This graft anastomosed to the ascending aorta was used as the proximal inflow of the temporary bypass graft. For the hemi-arch replacement procedure, the proximal inflow segment of the temporary bypass graft was anastomosed to the brachiocephalic artery. In both cases, the distal outflow segment of the temporary bypass graft was the graft used for repair of the abdominal aortic aneurysm. In order to prevent any clamp injury, Teflon felt was tightly wrapped around the aorta before the clamp was applied.

RESULTS

Evaluation of the hemodynamic parameters measured during cross-clamping of the aortic arch revealed stable distal perfusion to the visceral organs and no excessive increase in cardiac afterload. All patients had an uneventful postoperative course and were discharged within 1 month of surgery.

CONCLUSION

Our temporary bypass method is recommended for simultaneous replacement of aneurysms in the aortic arch and the abdominal aorta.

Retrocaval ureter and preaortic iliac venous confluence in a patient with an abdominal aortic aneurysm

Anomalous anatomic location of a large venous system poses a potential hazard in aortic operations. We encountered a patient with an infrarenal abdominal aortic aneurysm who was also found at preoperative contrast-enhanced computed tomography to have a retrocaval right ureter and a preaortic iliac vein confluence. This combined anomaly has not previously been reported except for one postmortem case. As abdominal aortic surgery is currently performed routinely, care must be taken to avoid injury to surrounding organs due to rare anatomic anomalies.

Molecular typing of methicillin-resistant Staphylococcus aureus in a university teaching hospital

Plasmid analysis and pulsed-field gel electrophoresis (PFGE) were used to study the epidemiologic relationship among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated at Tokyo Medical and Dental University Hospital. We found that 263 of 276 MRSA isolates had plasmids, which could be classified into 30 different patterns according to the number and plasmid molecular weight. Strains which harboured a single plasmid of approximately 13.4 Mds in molecular weight were the most numerous (55.7% of the isolates). These strains were isolated from 14 of 17 hospital wards. The largest number of strains with this plasmid pattern (33 strains) were isolated from a single ward. PFGE typing was then performed to further confirm the relationships among these 33 strains. The PFGE banding patterns of these strains were highly similar. The antibiogram profiles of these strains were also correlated with the PFGE pattern. Thus, the results suggest that these strains are epidemiologically related and spread throughout the ward. Combined plasmid analysis and PFGE were effective for discriminating the various MRSA isolates.