Posteroinferior Wall Research Articles

A clinico-anatomic study of the auricular branch of the vagus nerve and arnold's ear-cough reflex

The results of a clinico-anatomic study of the auricular branch of the vagus nerve (ABVN) and Arnold's ear-cough reflex are presented. The frequency of the ear-cough reflex was found to be 2.3% (12 out of 514 patients). It was bilateral in 3 cases (0.6%). The reflex was elicited by palpation of the postero-inferior wall of the external acoustic meatus (EAM) in 11 patients, and by palpation of the antero-inferior wall in one patient (0.2%). The reflex was frequently noticed to occur after a short latent period. The course of the ABVN inside the jugular foramen (JF), and distribution of the terminal branches of the ABVN in the external acoustic meatus were determined in 8 male cadavers (16 sides). In addition, the length of the mastoid canaliculus (MC) and the relationships of the ABVN with the facial nerve and stylomastoid foramen (SMF) were studied in both cadavers and 25 dry skulls (50 sides). High-resolution computed tomography (HRCT) scanning was also performed in all cadavers prior to microdissections. The ABVN emerged from the superior ganglion of the vagus nerve in all the cadavers. It ran between the internal jugular vein (IJV) and the bony wall of the jugular foramen. The ABVN was encased in a partial bony canal during its course from the jugular foramen to mastoid canaliculus in 18% of all specimens. The average length of the mastoid canaliculus was 5.6 mm (4.2-6.5), and it ran transversely towards the tympanomastoid suture 4.5 mm (4-5.1) above the stylomastoid foramen. The mastoid canaliculus was well demonstrated in all the HRCT scans.

Anatomic substrate for idiopathic left ventricular tachycardia.

Idiopathic left ventricular tachycardia (ILVT) characterized by QRS complexes with right bundle-branch block (RBBB) morphology and left axis deviation is a distinct clinical syndrome that also demonstrates a characteristic response to verapamil and inducibility from the atrium in patients without structural heart disease. A false tendon has been described in the left ventricle in a patient with ILVT in whom surgical resection of the false tendon resulted in cure. We hypothesized that the false tendon is responsible for the genesis of similar ventricular tachycardia (VT) in others. We performed transthoracic (TTE) and/or transesophageal (TEE) two-dimensional echocardiograms in 15 patients undergoing catheter ablation for ILVT. There were 12 men and 3 women (mean age, 31 +/- 12 years, with average symptom duration of 11 +/- 9 years). The mean VT cycle length was 360 +/- 70 ms, and all had RBBB morphology with left axis deviation. Cardiac chamber sizes, left ventricular wall thickness, and wall motion were normal in all ILVT patients. TTE and/or TEE demonstrated a false tendon extending from the posteroinferior left ventricular free wall to the left ventricular septum in all ILVT patients. The false tendons were thick (> or = 2 mm maximal thickness) in 5 patients and thin (< 2 mm maximal thickness) in 10 patients. We compared ILVT patients with a control group of 671 consecutive patients referred for echocardiography for other reasons. The mean age for the control group was 42 years. A false tendon was seen in the left ventricle in 34 of 671 (5%). In the control group patients with a false tendon, 2 patients had a history of VT (left bundle-branch block morphology) and 1 had ventricular fibrillation. The false tendons in the control patients were also oriented transversely across the ventricular cavity but were somewhat thinner (< 2 mm maximal thickness in 32 of 34 patients). Catheter ablation with the use of radiofrequency and/or direct current applied to the posteroapical septum resulted in cure in 14 of 15 patients. A false tendon extending from the posteroinferior left ventricle to the septum is a consistent finding in patients with ILVT and probably is responsible for this unique arrhythmia. The mechanism by which the false tendon precipitates tachycardia is speculative, but possibilities include conduction through the false tendon or by producing stretch in the Purkinje fiber network on the interventricular septum.

Cocaine-induced transmural myocardial infarction in a Yorkshire swine with normal coronary arteries: Evidence for microvascular and/or epicardial coronary artery spasm

Cocaine-induced myocardial infarction with normal coronary arteries is well documented in humans. The exact mechanism of action remains speculative. We report one case of cocaine-induced myocardial infarction with normal coronaries in one swine. Systemic hemodynamics and angiographic, electrocardiographic, echocardiographic, and histopathologic data are presented. Intravenous cocaine (1, 3, 10 mg/kg) produced significant decreases in mean arterial pressure, heart rate, stroke volume, coronary blood flow, and coronary reserve, whereas pulmonary artery diastolic pressure and coronary vascular resistances increased. Left anterior descending and left circumflex coronary artery cross-sectional area decreased by 31% and 64%, respectively, without localized vasospasm. Electrocardiographic changes occurred (3 mm ST elevation in leads II, III, AVF). Peak creatine phosphokinase was 17,220 IU/L. The echocardiogram revealed severe hypokinesis of the inferior wall and normal ventricular function. The animal survived the acute phase of the infarction and the swine was restudied 12 weeks later. Upon rechallenge, systemic and coronary hemodynamics shoved changes similar to those in the previous study. The swine developed ventricular fibrillation and expired after the 10 mg/kg cocaine dose. Macroscopic examination of the external surface of the heart revealed marked diffuse fibrosis in the posteroinferior and lateral left ventricular wall. Our data suggest that the infarct induced by cocaine may have resulted from severe vasoconstriction or spasm at the level of the microcirculation, and/or the epicardial coronary arteries, which shoved slight but significant narrowing throughout their lengths.

A possible mechanism for pacemaker-induced T-wave changes.

The genesis and the significance of pacemaker-induced T-wave changes remain unclear. Changes in body surface potential mapping (BSM) were observed and compared with resting thallium-201 myocardial scintigraphy (T1-SC) findings before, during and after ventricular pacing (VP) in 10 patients with various bradyarrhythmias. All studies were performed with the patients taking no medication. In all patients, isoarea QRST maps showed a characteristic abnormal dipolar pattern with positive values distributed over the upper chest and negative values over the lower chest during VP at a physiological rate for 14 days or more. These abnormalities were preserved almost completely after pacing was terminated; and coincided with deep T-wave inversions in leads II, III, aVF and V4-6. In three patients, BSM performed before VP showed normal QRST isoarea maps with positive values distributed over the left lower chest. All patients in whom resting T1-SC was performed during chronic VP showed transient perfusion defects in the posteroinferior (seven cases) or inferolateral (one case) left ventricular wall. In three patients, T1-SC was performed before VP and showed a normal distribution. Both the pacing-induced perfusion defects and the T-wave abnormalities remained unchanged 2 h after ceasing VP, were attenuated 7 days later and disappeared within a month. These findings suggest that chronic ventricular pacing may produce myocardial ischaemia, and that it persists for a certain period after the cessation of pacing, resulting in post-pacing T-wave inversion.

Daño miocárdico secundario a asfixia neonatal grave

Sixteen newborn infants with severe asphyxia were prospectively studied for evidence of secondary myocardial damage and, in that case, their clinical findings. Myocardial damage was diagnosed in three term newborn infants of adequate weight for gestational age (18.7%) by means of serial electrocardiograms taken in the first 72 hours of life. Two of them showed evidence of diffuse subendocardial ischemia and a third one showed electrocardiographic signs suggesting necrosis of the left ventricular posteroinferior wall. Neither creatine-phosphokinase serum activity nor its muscle brain MB isoenzyme were useful in the identification of myocardial damage. All three affected neonates developed respiratory distress syndrome without signs of cardiac failure and one of them died. The histopathological study of this late one showed localized hemorrhage of the papillary muscles and interventricular septum. These finding underscore the need for serial electrocardiographic recordings in newborns with severe asphyxia, since cardiac dysfunction may inadvertently occur under the appearance of respiratory distress syndrome.

Site and Size of Bleeding Peptic Ulcer. Is there any Relation to the Efficacy of Hemostatic Sclerotherapy?

In 78 patients with high-risk bleeding peptic ulcers (either with active bleeding or non-bleeding visible vessel) endoscopic hemostasis by injection of adrenaline and polidocanol was attempted. Sclerotherapy was performed in 70 (90%) patients. Initial hemostasis was achieved in 35 (94.5%) patients with active bleeding, and permanent hemostasis in 61 (87%). Efficacy of injection therapy was significantly lower in ulcers larger than 2 cm (p = 0.001), and in those located on the posteroinferior duodenal wall (p = 0.03). It was not possible to perform endoscopic injection in 8 (10%) patients due to difficulty of access, lesions located mainly high on the lesser gastric curvature and on the posteroinferior duodenal wall. From these results we conclude that endoscopic injection is a very useful technique for the initial treatment of high-risk bleeding peptic ulcer, although the size and anatomical location of the lesions may be a limitation of its use.

Diagnosis of Recent Myocardial Infarction With Quantitative Backscatter Imaging: Preliminary Studies

Acute myocardial ischemia and chronic myocardial infarction may be recognized with ultrasound tissue characterization techniques because of myocardial acoustic changes caused by reduced perfusion and/or collagen deposition. Our purpose was to study the acoustic properties of recent myocardial infarction when the predominating pathologic finding was myocardial edema and leukocytic infiltration. We used a new quantitative backscatter imaging system to study 18 patients 9 +/- 5 days after myocardial infarction (eight patients with anteroseptal myocardial infarction and 10 with inferior myocardial infarction) and 20 normal subjects. The cyclic variation of relative integrated backscatter (end-diastolic minus end-systolic) was calculated from on-line measurements. Standard parasternal long- and short-axis and apical four- and two-chamber views were obtained. In the anteroseptal myocardial infarction group, the cyclic variation of relative integrated backscatter was lower in the septum (1.5 +/- 1.6 dB) than in the posteroinferior wall (3.2 +/- 1.2 dB); however, the sample size of only three patients (of eight patients imaged) in the latter group prevented statistical comparison. The cyclic variation of relative integrated backscatter in the infarcted septum was less than the measurement obtained in the septum of the control group (4.3 +/- 2.4 dB, p less than 0.05). In the inferior infarction group, the cyclic variation of integrated backscatter in the posteroinferior wall (1.8 +/- 1.7 dB) was not significantly different from the measurement obtained in the septum (3.7 +/- 3.6 dB); however, the cyclic variation in the posteroinferior wall was significantly less than that obtained in the control group posteroinferior wall (5.7 +/- 1.7 dB, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study between a new, 50-degree right-semidecubital scanning and usual supine scanning of thallium-201 myocardial tomography for evaluation of coronary artery disease.

Images of thallium-201 cardiac tomography in the 50-degree right-lateral-semidecubital vs. usual supine positions were compared after a single dose of the isotope in 225 patients with or suspected of coronary artery diseases. Compared with the supine position method, the semidecubital position method enabled 25% shortening of the orbital radius (20.0 +/- 0.9 cm to 15.3 +/- 0.6 cm, n = 174, p less than 0.05), higher posteroinferior wall counts in both exercise and 3-hour-delayed images by up to 18%, better image sharpness and contrast, less motion artifact, more marked redistribution in the ischemic walls, and significantly higher specificity (57% vs. 78%, p less than 0.05) and accuracy (63% vs. 79%, p less than 0.05) for inferior wall lesions. The results indicate that the thallium cardiac scan is significantly affected by patient position during scanning, i.e., artifactual inferior wall defects due to photon attenuation in the supine position method. The semidecubital position method is recommended to minimize this artifact. The method is simple, easy to perform, well tolerated, feasible in any 1-headed tomography system, inexpensive, and free of running costs.

外耳道の特発性壊死性骨炎

A 59-year-old man came to our clinic with complaints of itching, otalgia and otorrhea of the left ear for three months. An ulcer was found in the osseous portion of the left external canal. It was located on the postero-inferior wall of the canal about 7-8mm from the ear drum. Fragments of necrotized bone and bloody pus were prescnt in the ulcer. Staphylococcus epidcrmidis was isolated in a culture of the pus. In spite of conservative therapy for one month, nccrotized bone fragments could be removed easily from the ulcer, and the bony defect became larger. Therefore, surgical removal of the necrotized bony external canal was performed, and the wound was covered with a pedicled flap from the temporal muscle. The extracted specimen contained necrotic bone and fibrotic granulation. The diagnosis was benign necrotizing osteitis of the external auditory meatus. There was no recurrence during the 21-month postoperative follow-up. This disease causes ulceration and necrosis of the osseous external auditory meatus. It is clinically rare, and differentiation from cholesteatoma of the external meatus is often difficult.

A new scanning method for thallium-201 myocardial SPECT: semidecubital position method.

The authors have developed a new scanning method for Tl-201 myocardial SPECT using a rotating gamma camera with 180-degree data collection. This requires a new type of imaging table on which the patient is placed in a 50-degree right semidecubital position to allow close proximity to the camera-collimator system. Using this method, attenuation by the imaging table is completely avoidable because the projected views in the left oblique directions are not obstructed by the table. In addition, the radius of camera rotation is about 25% shorter than in the conventional method. Phantom and 16 clinical studies were performed to compare the performance of conventional and semidecubital position methods. In phantom studies, tomographic images produced using the new method showed better lesion contrast and more counts in the posteroinferior wall of the heart than those produced using the conventional method. Clinically, 12 of the 16 studies showed more counts in the posteroinferior wall of the heart with the semidecubital position method than with the conventional method. The semidecubital position method is useful for Tl-201 myocardial SPECT, especially for evaluation of posteroinferior wall hypoperfusion.

Recurrent Sustained Ventricular Tachycardia Solely Responsive to Verapamil in a Patient with a Remote Myocardial Infarction

A 49-year-old man with a silent remote postero-inferior wall myocardial infarction exhibited recurrent episodes of sustained ventricular tachycardia which was hemodynamically well tolerated. Ventricular tachycardia was neither terminated nor prevented by therapy with multiple class I and class III antiarrhythmic drugs. In contrast, ventricular tachycardia was repeatedly terminated within a few minutes following intravenous administration of 10 mg verapamil and did not recur during oral therapy with verapamil (360 mg daily). Electrophysiologic study suggested that ventricular tachycardia was due to a reentrant mechanism rather than to triggered or abnormal automaticity. Thus, in contrast to previous reports, findings in this patient indicate that verapamil may be very effective and safe in certain types of ventricular tachycardia occurring late after a myocardial infarction.

Echocardiographic evaluation of left ventricular function during coronary artery angioplasty

Balloon occlusion of a stenotic coronary artery during percutaneous coronary artery angioplasty provides a unique opportunity to study the effect of acute myocardial ischemia on left ventricular (LV) function. Simultaneous M-mode and 2-dimensional (2-D) echocardiograms and a 6-lead electrocardiogram were recorded during 20 episodes of coronary artery occlusion and release in 12 patients. No patient had previous myocardial infarction and all had normal LV function by angiography. All patients had isolated single coronary artery disease, with left anterior descending stenosis in 8 and right coronary stenosis in 4. In 18 of 20 episodes (90%), M-mode echocardiography during balloon occlusion revealed a significant (p <0.001) decrease in LV systolic, diastolic and percent systolic wall thickness; systolic excursion; systolic and diastolic endocardial velocities; and fractional shortening. These changes were observed in the area of the ventricular septum in patients with left anterior descending occlusion and posteroinferior wall in those with right coronary artery occlusion. Two-dimensional echocardiography revealed varying degrees of hypokinesia, akinesia and dyskinesia during balloon occlusion in 18 instances. The echocardiogaphy changes were observed within 15 to 20 seconds of balloon occlusion and resolved 10 to 20 seconds after balloon deflation. All patients who had echocardogaphy changes during balloon occlusion also had concomitant electrocardiographic (ECG) ST-segment elevation, whereas 2 patients with normal LV function had no ECG changes. Both of these patients had profuse collateral blood supply to the stenotic coronary artery. The echocardiographic and ECG abnormalities increased proportionately to the length of balloon occlusion. This study confirms previous animal and recent human studies of transient LV dysfunction during coronary occlusion. Echocardiography during balloon angioplasty provides a unique model to study the effects of myocardial ischemia in humans.

Acute Posteroinferior Wall Myocardial Infarction Secondary to Football Chest Trauma

Myocardial infarction secondary to nonpenetrating chest trauma is rare. We present the case of a sportsman who developed an acute transmural posteroinferior wall myocardial infarction due to chest trauma by a football. The angiographic study revealed total obstruction of the proximal right coronary artery.

Effects of progressive reduction in coronary blood flow on regional and global left ventricular contraction and relaxation during normal and increased afterload: a roentgen videometric study.

The effects of step-wise reduction in left circumflex coronary blood flow on: 1) posteroinferior wall dynamics; 2) normally-perfused anterior wall dynamics; and 3) cavity function were assessed simultaneously by roentgen videometric analysis of left ventricular angiograms in open-chest dogs during normal and increased afterload. At control coronary flow with normal afterload, peak rates of systolic thickening and diastolic thinning of the posteroinferior and anterior walls were similar. Step-wise reduction in circumflex coronary flow resulted in a progressive fall in systolic and diastolic posteroinferior wall dynamics. Increased LV afterload resulted in a decrease in posteroinferior wall dynamics even at control coronary flow, and reduction in flow resulted in even greater deterioration than occurred with normal afterload. The decrease in posteroinferior wall dynamics with reduction in circumflex coronary flow was accompanied by an increase in peak rates of systolic thickening and diastolic thinning of the normally perfused anterior wall. The level of coronary blood flow at which this increase in anterior wall dynamics occurred, varied with LV loading conditions, occurring earlier when afterload was increased. There was no earlier or greater decrease in diastolic than systolic wall dynamics with progressive reduction in coronary flow with either normal or increased afterload. Left ventricular end-diastolic volume, end-diastolic pressure and ejection fraction changed little until coronary blood flow was reduced to 50% of control; by contrast, stroke-work was exquisitely sensitive to changes in coronary flow. There was no correlation between changes in regional and cavity systolic or diastolic function. The delay in onset of LV cavity dysfunction with ischemia may have been partly due to the "compensatory increase" in anterior wall dynamics, counterbalancing the impaired posteroinferior wall dynamics.

Detection and assessment of severity of regional ischemic left ventricular dysfunction by digital fluoroscopy

Digital intravenous ventriculography (DIV) was used to detect and assess the severity of regional and global left ventricular (LV) function in the presence of graded levels of coronary stenosis. DIV was performed on six anesthetized dogs with a coronary blood flow probe and micrometer controlled occluder on the circumflex coronary artery (CXA) and pairs of sonic dimension crystals in the posterointerior (ischemic area) and anterior (control area) walls of the LV in the control state, with subtotal occlusion of the CXA (STEN), and with CXA occlusion (OCL). Global analysis at each stage included area-length calculation of end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF). Regional analysis included calculation of area displaced by anterior wall (AA), and posteroinferior wall (IA), average amplitude of excursion of the anterior wall (AE), and posteroinferior wall (IE). STEN caused significant increase in AA (14.4 ± 2.2%) and decreases in EF (−19.7 ± 2.5%), IA (−36.6 ± 4.2%), and IE (−30.8 ± 5.3%) ( p < 0.05). With OCL, there were significant increases in EDV (78.7 ± 7.6%), ESV (225 ± 20.6%), AA (42.6 ± 10.3%), and AE (25.5 ± 4.3%); with further fall in EF (−42.4 ± 2.1%), IA (−94.3 ± 6.6%), and IE (−84.7 ± 9.4%) ( p < 0.01). Regional functional indices derived from DIV detected regional wall motion abnormalities, when these were shown to be present by sonocardiometer measurements of myocardial segment length and extent of shortening in the ischemic region of the LV. We conclude that DIV is a sensitive technique for the detection and assessment of severity of regional and global LV dysfunction in ischemic heart disease.

The suspensory mechanism of the uterus

At rest the uterovaginal tube presents three angles in the sagittal plane: anteflexion, anteversion and the vaginal cap. The most important, from the functional point of view, is the angle of anteversion because it places the uterus perpendicularly in relation to the vagina. This arrangement may be explained by the erect posture of the human being and commences with the toddler as she begins to stand on her feet. The uterus is tethered on each side to the pelvic wall by a bulky neurovascular pedicle composed of uterine and vaginal vessies, the hypogastric plexus and connective tissue in continuity with that of the retroperitoneal space. This pedicle, in passive fashion, maintains the position and direction of the uterus and thanks to its elasticity allows it to mould itself to the variations in volume of the bladder and rectum and take up its normal position once these organs are emptied. The histological structure of this pedicle cannot account for its effectiveness as a suspensory ligament. Support for the uterus in fact derives from the posterior part of the levator muscles of the anus. At rest the uterus lies behind the urogenital fissure. During effort it gains support by the intermediary of the rectum on the posterior part of the anal elevators and the anococcygeal ligament; it thus closes off the pouch of Douglas. The vaginal orifice, which represents a weakness in the muscular diaphragm of the pelvis, is closed during effort by abutment of the anterosuperior wall of the vagina onto the posteroinferior wall. The vagina, almost in the horizontal position, traverses the muscular diaphragm of the pelvis obliquely from above downwards and is thus situated almost perpendicular to the forces of rectal emptying. Contraction of the muscular diaphragm of the pelvis, on account of its bony attachments being diametically opposed, does not close off the urogenital fissure which in the living subject lies very anteriorly in a subpubic position. Contraction results in the anal levators becoming horizontal and displacing the pelvic viscera upwards.

Pure right ventricular infarction

The case is reported of a patient with chronic emphysema and cor pulmonale who developed the signs of acute myocardial infarction which were initially interpreted as being localized in the postero-inferior wall of the left ventricle. The patient rapidly developed the features of massive right heart failure in the absence of pulmonary congestion, a condition thought to be due to pulmonary emboli. The autopsy, however, revealed a pure right ventricular infarct, which covered more than half of the pre-existent right ventricular myocardium, in the setting of marked right ventricular hypertrophy infraction. The case furthermore shows that the possibility of pure right ventricular infarction should be evaluated in all patients with puzzling right heart failure, in the course of what initially is thought to be an acute left ventricular infraction, is important since therapy with plasma volume expanders should be used with great caution in such patients

New approaches to resolving diagnostic problems in patients with angina pectoris.

Several new noninvasive techniques are now available to evaluate the patient with chest pain to determine if myocardial ischemia is present. Continuous ambulatory ECG monitoring can detect myocardial ischemia in some patients who have normal ECG responses to graded exercise tests. Defects in myocardial perfusion can be visualized by radionuclide imaging at rest and after exercise. Also, abnormal left ventricular wall motion due to myocardial ischemia can be detected by gated blood pool scanning at the same time. Other techniques can olso be valuable in evaluating wall motion. Standard M-mode echocardiography can detect anteroseptal and posteroinferior wall motion abnormalities with remarkable anatomic detail, and newer echo techniques are promising for delineating the motion of other parts of the left ventricle. Finally, abnormal contractile areas can be assessed by videotracking the fluoroscopic cardiac silhouette and by a new noninvasive technique, the displacement cardiograph, which does not involve radiation exposure. Although none of these tests are both highly sensitive and highly specific for myocardial ischemia, their combined application in a symptomatic patient may provide considerable useful information which will help to determine who should be subjected to the risk and expense of coronary arteriography.

The treatment of malignant ventricular tachycardia by aorto-coronary saphenous vein bypass graft

Summary A 61-year-old man with a previous cardiac infarction had at least fifteen attacks of ventricular tachycardia which finally did not respond to either drug or electrical therapy. Angiography showed a blocked right coronary artery and a non-contractile portion of postero-inferior left ventricular wall. An aorto to right coronary saphenous vein bypass graft was inserted, and although attacks of tachycardia occurred following the operation these were of short duration and reverted spontaneously. He has been free of tachycardia for 5 weeks, with a greatly improved effort tolerance.

Transient left posterior hemiblock. Report of four cases induced by exercise test.

Four cases with transient electrocardiographic features which have been attributed to left posterior hemiblock (LPH) are reported. These features were induced by the exercise test in patients with severe coronary artery disease. In all of them the following exercise-induced changes were noted: (1) A shift of the main QRS forces inferiorly and to the right (between +90° and +120°). (2) A definite shift of the initial 0.02 QRS vectors superiorly and to the left, causing a small Q wave to appear in leads II, III, and aV F and/or to disappear from leads I and aV L . (3) A S I Q III pattern. (4) A leftward displacement of the precordial transition zone. (5) An increase of QRS duration in about 0.02 sec. Gradual disappearance of the exercise-induced axis shift was observed in all four cases and these findings were compatible with multiple degrees of "incomplete" LPH. The occurrence of transient LPH patterns was related to the development of acute, transient injury in the posteroinferior wall of the left ventricle in the presence of segmental or widespread coronary artery disease and chronic posteroinferior damage. Before the exercise test, two patients had electrocardiographic patterns suggesting old myocardial infarction and the other two had repolarization changes related to inferior myocardial ischemia according to the angiographic findings.