Use of technetium-99m sestamibi ECG-gated single-photon emission tomography for the evaluation of left ventricular function following coronary artery bypass graft: comparison with three-dimensional magnetic resonance imaging.

In patients who had undergone cardiac surgery (coronary artery bypass graft) and whose hearts showed abnormal movement during the cardiac cycle, we studied the accuracy of functional assessment using ECG-gated single-photon emission tomography (SPET) and the automated software developed by Germano et al. by comparing the findings with magnetic resonance (MR) images acquired three-dimensionally. Sixteen patients who had undergone cardiac surgery underwent 99mTc-sestamibi gated SPET (MIBI-g-SPET) and MRI on the same day.

The influence of interleukin-1 receptor antagonist transgene on spiral ganglion neurons.

The cytokine interleukin-1beta (IL-1) has been shown to induce the secretion of NGF and GDNF in several types of neuronal populations. IL-1 has also been shown to mediate immune response following trauma or presence of foreign antigens. We investigated the influence of an IL-1 antagonist on the survival of spiral ganglion neurons in inner ears in which hair cells have been eliminated.

Should the pericardium be closed routinely after heart operations?

Background: Repeat coronary artery bypass grafting is more difficult if the right ventricle is firmly attached to the inner table of the sternum. Closure of the pericardium at the time of the initial procedure may prevent attachment of the right ventricle to the sternum. This study attempts to identify the geometric effects of pericardial closure early after isolated coronary artery bypass grafting.

Reactive oxygen species play an important role in the activation of heat shock factor 1 in ischemic-reperfused heart.

Background: The myocardial protective role of heat shock protein (HSP) has been demonstrated. Recently, we reported that ischemia/reperfusion induced a significant activation of heat shock factor (HSF) 1 and an accumulation of mRNA for HSP70 and HSP90. We examined the role of reactive oxygen species (ROSs) in the induction of stress response in the ischemic-reperfused heart.

Mitral annular size and shape in sheep with annuloplasty rings.

Background: Mitral annuloplasty is an important element of most mitral repairs, yet the effects of various types of annuloplasty rings on mitral annular dynamics are still debated. Recent studies suggest that flexible rings preserve physiologic mitral annular area change during the cardiac cycle, while rigid rings do not.

Methods: To clarify the effects of mitral ring annuloplasty on mitral annular dynamic geometry, we sutured 8 radiopaque markers equidistantly around the mitral anulus in 3 groups of sheep (n = 7 each: no ring, Carpentier-Edwards semi-rigid Physio-Ring [Baxter Healthcare Corp, Edwards Division, Santa Ana, Calif], and Duran flexible ring [Medtronic, Inc, Minneapolis, Minn]).

Bilateral internal thoracic artery grafting may improve outcome of coronary artery surgery. Risk-adjusted survival.

Background: Excellent clinical results of the patients with single left internal thoracic artery (ITA) grafting compared with saphenous vein grafting have prompted surgeons to use both ITAs. However, long-term benefits of the bilateral ITA grafting have not been proven.

Methods And Results: We reviewed our experience of 2826 patients (age 62 +/- 9 years [mean +/- 1 SD], 2350 men, mean follow-up 52 months) who underwent surgery with ITAs, supplemented by saphenous vein grafts when required, between 1985 and 1995.

Estimation of regional left ventricular wall stresses in intact canine hearts.

Left ventricular (LV) wall stress is an important element in the assessment of LV systolic function; however, a reproducible technique to determine instantaneous local or regional wall stress has not been developed. Fourteen dogs underwent placement of twenty-six myocardial markers into the ventricle and septum. One week later, marker images were obtained using high-speed biplane videofluoroscopy under awake, sedated, atrially paced baseline conditions and after inotropic stimulation (calcium).

Results of chronic animal experiments with a new version of a magnetically suspended centrifugal pump.

We have developed a magnetically suspended centrifugal pump (MSCP) for long-term ventricular support. This study reports results of chronic animal experiments using a new version of the MSCP. Three sheep weighing 50-70 kg were used in this study.

[Coronary stenosis and mechanisms of collateral vessel growth].

The presence or absence of collateral circulation significantly impacts the natural history of coronary artery disease. Collateral growth involves two different mechanism; capillary collaterals develop by sprouting (angiogenesis) and muscular collaterals develop in situ from preexisting arterioles (arteriogenesis). The process is mediated by various angiogenic growth factors such as VEGF, FGFs, IGF-1 and PDGF.

Auditory pathway and auditory brainstem response in mice lacking NMDA receptor epsilon 1 and epsilon 4 subunits.

There is considerable evidence that the N-methyl-D-aspartate receptor (NMDAR) is a component of excitatory amino acid synapses in the ascending auditory pathway. The availability of mice that are defective in NMDAR epsilon 1 or NMDAR epsilon 4 subunit paves the way for investigations on the role of this receptor in auditory function. Non-radioactive in situ hybridization was used in the parent C57/6J wild strain to determine if these subunits are normally expressed in cochlear nucleus (CN) and superior olivary complex (SOC) and to confirm their absence in the respective mutant mice.

Early systolic mitral leaflet "loitering" during acute ischemic mitral regurgitation.

Background: The mechanism by which incomplete mitral leaflet coaptation develops during ischemic mitral regurgitation is debated, with recent studies suggesting that incomplete mitral leaflet coaptation may be due to apically displaced papillary muscle tips. Yet quantitative in vivo three-dimensional mitral leaflet motion during ischemic mitral regurgitation has never been described.

Methods: Radiopaque markers (sutured around the mitral anulus, to the central free mitral leaflet edges, and to both papillary muscle tips and bases) were imaged with the use of biplane videofluoroscopy in six closed-chest, sedated sheep before (control) and during induction of acute ischemic mitral regurgitation.

Mitral valve opening in the ovine heart.

To study the three-dimensional size, shape, and motion of the mitral leaflets and annulus, we surgically attached radiopaque markers to sites on the mitral annulus and leaflets in seven sheep. After 8 days of recovery, the animals were sedated, and three-dimensional marker positions were measured by computer analysis of biplane videofluorograms (60/s). We found that the oval mitral annulus became most elliptical in middiastole.

The road to complete arterial grafting for coronary artery disease.

In 1984, our department moved to the use of single, and subsequently, bilateral internal thoracic artery grafting which, when reviewed after 12 years, suggest the addition of a second internal thoracic artery is beneficial. The 10-year survival using all-cause mortality was 86.9% for bilateral internal thoracic artery grafting compared with 74.

Geometric determinants of ischemic mitral regurgitation.

Background: The precise geometric determinants of ischemic mitral regurgitation (MR) are incompletely understood, although such knowledge is important to improve mitral valve reparative techniques.

Methods And Results: The three-dimensional geometry of the mitral apparatus was studied using radiopaque markers in eight closed-chest dogs with acute posterior left ventricular wall ischemia either with (MR) or without (no-MR) MR as assessed by using color Doppler. Using a cylindrical coordinate system (origin at the midpoint between the mitral annulus commissures [anterolateral and posteromedial] and z-axis directed toward the left ventricular apex), we measured the distance to the midpoint (z, in millimeters), radial distance from the z-axis (r, in millimeters), and angle from the intercommissural line (theta) of each marker.

Most ovine mitral annular three-dimensional size reduction occurs before ventricular systole and is abolished with ventricular pacing.

Background: Conventional surgical thinking indicates that mitral annular (MA) size reduction plays a key role in mitral valve closure, and most MA size and shape changes are thought to occur during left ventricular (LV) systole. The influences of left atrial (LA) and LV systole on MA size and shape, however, remain debated.

Methods And Results: Eight radiopaque markers were placed equidistantly around the MA and imaged using high-speed simultaneous biplane videofluoroscopy in seven closed-chest, sedated sheep before and during asynchronous LV pacing.

Complete unloading alone may not adequately protect the left ventricle.

Background: The benefit of left ventricular (LV) unloading for preserving LV function is commonly accepted, but its efficacy remains incompletely defined.

Methods: We studied the influence of complete LV unloading on LV systolic and diastolic mechanics using an in situ isovolumic preparation with two different coronary perfusion pressures (CPPs) in 12 dogs during prolonged normothermic cardiopulmonary bypass.

Results: Multivariate analysis of covariance with time as a covariate revealed that a high CPP (143 +/- 36 mm Hg; n = 6) was associated with better preservation of systolic LV function over time as assessed by LV end-systolic elastance (p < 0.

Further evidence for supporting cell conversion in the damaged avian basilar papilla.

Two lines of evidence suggested that a process other than supporting cell divisions may give rise to new hair cells in the bird inner ear injured by either noise or ototoxic drugs. This process, supporting cell conversion, occurs when non-dividing supporting cells transdifferentiate into hair cells. First, noise-exposed chicks received zero, one or two daily i.

Septal function during left ventricular unloading.

Background: Left ventricular (LV) unloading with mechanical support devices alters biventricular geometry and impairs right ventricular (RV) contractility, but its effect on septal systolic function remains unknown.

Methods And Results: To evaluate the effects of LV volume and pressure unloading on septal geometry and function, LV preload was abruptly reduced by clamping left atrial pressure between 0 and -2 mm Hg in seven open-chest, anesthetized dogs by use of a pressure-control servomechanism to withdraw blood from the left atrium. With left atrial pressure clamping, maximal LV pressure decreased 30 +/- 12% (mean +/- SD) (P < .

How good is the radial artery as a bypass graft?

The radial artery is being used with increasing frequency to replace the saphenous vein as a coronary artery bypass graft, on the basis of the belief that it will provide improved long-term patency. Innovative techniques in assessing the ulnar collateral circulation to the hand continue to evolve, giving comfort to the surgeon. Several centres have confirmed that the early results of surgery using the radial artery are similar to those using conventional grafts.

Papillary muscle-left ventricular wall "complex".

Objectives: Mitral valve homografts, despite theoretical advantages, are not widely used, in part because of lack of basic information about the three-dimensional geometry of the mitral apparatus.

Methods: Radiopaque markers were used in the study of eight closed-chest dogs under four conditions: (1) baseline, (2) caval occlusion, (3) tachycardia (atrial pacing), and (4) nitroprusside infusion. Using a cylindrical coordinate system.

Gentamicin distribution in the basilar papilla: possible association with regenerated hair cell orientation.

Gentamicin-specific immunolabeling was examined in the regenerating chick basilar papilla following gentamicin treatment. Surviving hair cells were labeled in the infracuticular area, predominantly in the basal body region. Label intensity in short hair cells (SHCs) was greater than tall hair cells (THCs).

Three-dimensional dynamic geometry of the normal canine mitral annulus and papillary muscles.

Background: Despite an incomplete knowledge of the geometry and dynamics of the mitral annulus (MA), papillary muscle (PM), and the chordae tendineac, chordal-sparing MVR is popular.

Methods And Results: The systolic reduction in three-dimensional distance between each PM tip and eight MA sites (DT-A) was measured in nine normal closed-chest dogs by use of surgically implanted radiopaque markers. Three loci (tip, junction, and base) on each PM were also projected onto the MA plane at end diastole and end systole to assess PM dynamics.

Loss of three-dimensional canine mitral annular systolic contraction with reduced left ventricular volumes.

Background: We have recently described an inhomogeneous pattern of systolic contraction of the mitral annulus (MA) in normovolemic dogs: the posterior annulus shortens, and the anterior annulus lengthens. MA dynamics, however, have not been studied in volume-depleted hearts.

Methods And Results: Eight radiopaque markers were placed equidistant from each other around the MA in seven dogs.

Three-dimensional dynamics of the canine mitral annulus during ischemic mitral regurgitation.

Background: It has been suggested that ischemic mitral regurgitation results, at least in part, from generalized end-systolic mitral annulus (MA) dilatation, but the role of the MA is incompletely understood and the segmental dynamics of the MA during left ventricular ischemia have not been described.

Methods: We used radiopaque markers and simultaneous biplane videofluoroscopy to measure three-dimensional in vivo lengths of eight MA segments in 7 sedated dogs before and after induction of ischemic MR (produced by circumflex coronary artery balloon occlusion and verified by Doppler echocardiography). As viewed from the left atrium, the MA segment between markers 1 and 2 (S12) was defined as starting at the posteromedial commissure, and remaining segments were numbered sequentially clockwise around the MA (ie, the posterior MA encompassed S12, S23, S34, S45,; the anterior MA included S56, S67, S78, S81).