Dual left anterior descending coronary artery: Angiographic description of important variants and surgical implications

Twenty-three cases of an anatomic variant of the left anterior descending artery (LAD) are described. This variant is termed “dual LAD” and consists of two branches which supply the usual distribution of the LAD. One branch (short LAD) terminates in the proximal aspect of the anterior interventricular sulcus (AIVS). A second, longer branch has a variable course outside the AIVS and returns to the AIVS distally. The long LAD arose from the LAD proper in 21 cases and from the RCA in two cases. The initial course of the long LAD was on the epicardial surface of the left ventricle (17 cases), right ventricle (three cases), or within the interventricular septum (three cases). Recognition of these variants is important for correct surgical identification of the short and long LADs.     

Bacterial endocarditis presenting as complete heart block with paradoxical (left-to-right) pulmonary emboli

The patient described presented with fever, heart block, negative blood cultures, and clinical evidence of aortic insufficiency. He was unresponsive to antibiotic therapy. Cardiac catheterization demonstrated an acquired left-to-right shunt which was probably the source of paradoxical pulmonary emboli. Surgical replacement of the infected aortic valve and closure of the demonstrated ruptured mycotic sinus of Valsalva aneurysm was curative. It is suggested that evolving intraventricular or atrioventricular conduction disturbances during the course of endocarditis indicate the presence of myocardial abscess or sinus of Valsalva aneurysm and should be taken as strong indications for prompt surgical intervention.     

Cardiac pacing and pacemakers II. Serial electrophysiologic-pharmacologic testing for control of recurrent tachyarrhythmias.

The place of pacemakers in the treatment of tachyarrhythmias has expanded far beyond the initial role in the brady-tachy syndrome, of providing a "minimum guaranteed rate" while medications suppress the tachycardia. Techniques have been developed for prevention, termination, and duplication of a patient's spontaneous tachycardia under safe catheterization laboratory conditions. Combined with accumulating information about the normal responses to electrophysiologic stresses, these techniques have led to a new dimension in arrhythmia control. Most tachycardias previously felt to be refractory can be controlled after serial electrophysiologic-pharmacologic testing, during which sequential pharmacologic and pacer regimens are tested until a combination is found which prevents induction of tachycardias, and/or a pace mode is found which reliably terminates the tachycardia. Use of such an approach reduces hospital admissions and referral for surgery, and eliminates prolonged hospitalization for assessment of therapy in patients with infrequent but potentially lethal spontaneous tachycardias.     

Significance of isolated H-V interval prolongation in symptomatic patients without documented heart block

Paced and unpaced control groups were followed to establish the roles of pacers and infranodal (H-V) conduction in 59 patients with symptoms consistent with intermittent heart block (HB). To reduce the number of variables compared with previous studies, patients were included only when (1) prior ECG monitoring and medical-neurologic evaluation failed to document HB or other cause for symptoms; (2) His bundle studies were normal or showed only H-V prolongation, and (3) there was no history of a recent myocardial infarction. Of 35 patients with prolonged H-V interval, 18 received permanent pacers, while 17 remained unpaced. Eighteen unpaced patients constituted the normal H-V Group (after two were lost to follow-up and four received pacers). All groups were similar in types of heart diseases, NYHA classification, general medical condition, age and sex, thus providing adequate controls.All patients with normal H-V intervals remained stable (no deaths or progression to HB) for a mean follow-up period of 22 months. Among 18 patients with prolonged H-V intervals who received pacers, there were three deaths, none sudden, during a mean of 23 months; four patients developed HB unaccompanied by symptoms. Among 17 patients with prolonged H-V intervals who were not paced, eight died (three suddenly) and three progressed to HB with symptoms, leaving only six stable after six months follow-up. All these parameters were significantly worse in the unpaced patients with prolonged H-V intervals.These results suggest that patients with intermittent symptoms consistent with heart block, whose H-V interval is ≥ 60 msec. should receive a permanent pacer even if intermittent HB cannot be documented before implant.     

Unsuspected meningioma in a patient with pituitary gigantism. Case report with autopsy findings

A unique example of a clinically unsuspected large parasellar meningioma is described in a 36-yr-old pituitary giant who had been treated initially with conventional irradiation, subsequently by surgical excision of an acidophil adenoma, and ultimately with medroxyprogesterone acetate (MPA) prior to his demise. The patient died of increased intracranial pressure resulting from a combined mass effect of the meningioma and recurrent tumor. The relationship between radiation and the development of the meningioma is discussed, as well as the fine ultrastructure of a highly functioning acidophil adenoma.     

Stability of AV conduction in sick sinus node syndrome patients with implanted atrial pacemakers

Single-chamber atrial pacing is effective in the management of sinus node dysfunction, subject to the uncertainty of long-term atrioventricular conduction. Despite the accepted observation that many patients with sinus node dysfunction also have atrioventricular conduction disease, data do not exist on the development of atrioventricular block in those patients with permanent single-chamber atrial pacing. Of 70 patients who received single-chamber atrial pacing from 1967 to 1982 (mean duration of pacing was 33 months), only two patients of 58 (3.4%) of those with sinus node dysfunction developed atrioventricular (AV) block—after 14 months in one patient and after 23 months of successful atrial pacing in the other. None of the 12 patients paced for tachyarrhythmia management developed AV block. Of the 70 patients, 37 had assessment of AV conduction by incremental atrial pacing at the time of implant and 20 patients underwent atrial pacing on the basis of surface ECG and clinical judgment. Electrophysiologic studies were conducted only in those patients being paced for control of supraventricular arrhythmias. Only 5 of the 70 patients required conversion to ventricular pacing for technical difficulties; three of these conversions occurred in the early 1970's before the advent of atrial tined or J leads; one was for irreparable lead fracture and only one occurred in a patient with a newer design atrial lead. In conclusion, progression to AV block in patients with permanent atrial pacing is uncommon; formal electrophysiologic studies are necessary mainly in patients with supraventricular arrhythmias; and in the majority of patients, AV conduction can be assessed at the time of implant. Continued improvement in atrial leads should make atrial pacing even more successful.     

Coronary steal: Its role in detrimental effect of isoproterenol after acute coronary occlusion in dogs

Using epicardial electrograms others have established that infusion of isoproterenol increases myocardial injury after acute coronary occlusion. To define the contribution of alterations in collateral blood flow to this increased ischemia, isoproterenol was administered to 10 dogs. After pretreatment with practolol in doses that successfully block inotropic but not vascular effects of beta adrenergic stimulants, intracoronary isoproterenol continued to enhance the magnitude of S-T segment elevation in ischemic areas. Thus, vasodilation induced by isoproterenol appears to divert flow from the ischemic area. To test this hypothesis, intracoronary adenosine was given to cause coronary vasodilation without enhancing inotropy. S-T segment elevation at ischemic and adjacent sites was significantly increased. Neither agent had systemic effects, but each increased coronary blood flow while concomitantly decreasing collateral flow as evidenced by a reduction in retrograde coronary flow and peripheral coronary pressure. In addition, adenosine significantly diminished the rate of xenon-133 clearance from the ischemic myocardium. Thus, isoproterenol, in addition to its positive inotropic effect, increases myocardial injury by its vascular action. Collateral blood flow to acutely ischemic myocardium is diminished by the production of a coronary steal. Intravenously administered isoproterenol additionally diminishes collateral flow by decreasing coronary perfusion pressure. It is postulated that any agent that causes either a primary or secondary coronary vasodilation may cause a coronary steal and subsequently enhance myocardial injury.     

Abnormal mitral valve motion associated with ventricular septal defect following acute myocardial infarction.

It is often difficult to make the clinical distinction between acute mitral regurgitation caused by papillary muscle dysfunction or rupture and ventricular septal defect complicating an acute myocardial infarction. A case of a patient with rapidly progressive congestive heart failure and a loud murmur is presented. Echocardiography strongly suggested the presence of a flail posterior mitral leaflet. However, the patient was subsequently found to have rupture of the interventricular septum. This diagnosis was made with bedside right heart catheterization and was later confirmed by left ventriculography and direct inspection at the time of surgery. The mitral valve apparatus was completely normal. Thus this case demonstrates the apparent lack of specificity of the accepted echocardiographic criteria for flail mitral leaflet and acutely ruptured interventricular septum, and the potential necessity of cardiac catheterization to distinguish between these entities.