The conduction system in rheumatoid arthritis with complete atrioventricular block.

Rheumatoid arthritis, of the peripheral type, or the ankylosing spondylitis type, with complete atrioventricular (A-V) block^1–11 or other conduction disturbances^12–18 has been sporadically reported. Very few conduction system studies have been done in these cases.^{3, 7–9, 17, 18} The present report deals with a comprehensive serial section study of the conduction system in a case of the peripheral type of rheumatoid arthritis with complete A-V block.     

Conduction system in systemic lupus erythematosus with atrioventricular block

We describe the clinical course and the postmortem cardiac findings in a 12 year old girl with systemic lupus erythematosus, complete heart block, renal failure and hyperkalemia. The conduction system was examined by serial section. The sinoatrial and atrioventricular nodes were found to be almost completely replaced by granulation tissue; we believe that this finding is related to the systemic lupus. The hyperkalemia is not considered to be the cause of the block, since the block persisted despite the lowering of the blood potassium level and the morphologic findings in this case are not found in hyperkalemia.     

Pathologic correlations in a case of complete heart block with split his potentials resulting from a stab wound of the heart

A 23 year old previously healthy man was stabbed in the anterior chest. This resulted in a ventricular septal defect and complete atrioventricular (A-V) block. The electrocardiogram revealed complete A-V block with a QRS pattern of right bundle branch block. His bundle recordings 26 days later revealed A-V dissociation with split His potentials (P-H₁ interval of 100 msec and H₂-V interval of 40 msec). During the study the escape QRS shifted from right to left bundle branch block with H₂ potentials still preceding each QRS interval with H₂-V intervals of 40 msec. A permanent pacemaker was implanted because of persistent congestive heart failure and bradycardia due to A-V block. The patient subsequently became asymptomatic. He died suddenly 3 $\text{1}\text{2}$ years later.Pathologically there were sizable openings in both the tricuspid and mitral valve substance and a ventricular septal defect involving the pars membranacea and part of the adjacent muscular septum. Serial sections of the conduction system revealed total destruction and fibrous replacement of the bifurcation and beginning of the right and left bundle branches and subtotal fibrous replacement of the branching bundle. Thus, the bifurcation of the bundle of His was totally absent at autopsy despite apparent electrophysiologic evidence of its existence 26 days after the stab wound. A possible explanation for this discrepancy is the subsequent fibrosis of the bifurcation produced by hemodynamic changes at the lower margin of the ventricular septal defect.     

Conduction system in a patient with Prinzmetal's angina and transient atrioventricular block.

His bundle recordings obtained during and between attacks of Prinzmetal's variant angina and transient atrioventricular (A-V) block were followed by a comprehensive serial section study of the conduction system in a 33 year old woman. Recordings between attacks showed normal A-H and H-V intervals. During an attack there was block proximal to the His bundle recording site. Pathologic studies revealed severe narrowing of the right coronary artery. Arteriolosclerosis of the heart was diffuse. Insignificant changes were found in the approaches to the A-V node and the A-V node itself. Major changes found in the left bundle branch had no counterpart in the electrocardiogram; the discordance in these findings is discussed.     

Mahaim and James fibers as a basis for a unique variety of ventricular preexcitation

This report concerns pathologic findings in a 54 year old woman with intermittent preexcitation who died of carcinoma of the breast. Electrocardiograms revealed predominantly normal sinus rhythm with a normal P-R interval and narrow QRS complex. Episodes of sinus rhythm, short P-R interval and QRS widening (with delta wave) were also recorded. During preexcitation QS complexes were noted in leads II, III, aVF, V₁ and V₄ to V₆. Delta waves were negative in leads II, III, aVF and V₁, isoelectric in leads V₄ to V₆ and positive only in leads I, aVL, V₂ and V₃. This case thus defies classification into any known variety of preexcitation.

Complete serial sections, cut through the entire conduction system and both atrioventricular (A-V) rims, totaled 18,600 sections. These revealed no bundle of Kent. Instead, Mahaim fibers histologically identified as His bundle tissue gave off from the A-V bundle to both the right and the left sides of the septum associated with the normal fibers of James. This case reveals that (1) fibers of James can bypass the A-V node, (2) fibers of Mahaim can conduct, and (3) there are types of preexcitation in addition to types A and B.     

Pathologic correlations in three cases of bilateral bundle branch disease with unusual electrophysiologic manifestations in two cases.

Examination of the conduction system in three patients with bifascicular block who had electrophysiologic studies forms the basis for this report. Patients 1 and 2 had left bundle branch block and Patient 3 right bundle branch block and left axis deviation. The H-V interval was prolonged in each case (70, 65 and 60 msec, respectively). Serial section examination of the conduction system revealed sclerodegenerative involvement of both bundle branches in all cases. In Case 1, atrial extrastimulus testing converted left to right bundle branch block; in Case 2, it delineated a sinus echo zone with repetitive sinus nodal reentrance. In the latter case serial section revealed extensive amyloid infiltration of the approaches to the sinoatrial (S-A) node and the atrial preferential pathways. In Case 3, with right bundle branch block and left axis deviation, serial section revealed greater involvement of the anterior part of the main left bundle branch than of the posterior portion as well as involvement of the second part of the right bundle branch. The study revealed excellent correlation between electrophysiologic and pathologic findings in three cases of intraventricular conduction disease and demonstrated an anatomic basis for the electrophysiologic findings resembling alternating bilateral bundle branch block. Sinus nodal reentrance may be related to disease in the approaches to the S-A node thereby causing delay in perinodal tissue allowing sinus reentrance. Finally in Case 3, the anatomic substrate for left axis deviation may lie in a greater involvement of the anterior portion than of the posterior portion of the main left bundle rather than in the corresponding portions of the periphery.     

Lack of connection between the atria and the peripheral conduction system in a case of corrected transposition with congenital atrioventricular block

This is the first documented histologic study of the heart of a patient with corrected transposition of the great vessels and congenital atrioventricular (A–V) block with no connection between the atria and an anterior type of peripheral conduction system. Musculature in the superior (anterior) walls of both atria was absent, as was the anterior A–V node. The peripheral conduction system began with the bundle of His. In place of the absent atrial musculature, fibrosis and calcification were present. The relation of laboratory evidence of connective tissue dyscrasia in the mother to the congenital A–V block in the child is discussed.     

Wenckebach periods with repetitive block: evaluation with His bundle recording

Two patients are reported in whom repetitive block of two consecutive P waves occurred during Wenckebach beating induced by atrial pacing. His bundle recordings revealed block proximal to H in the first case, suggesting inhomogeneous conduction in the A-V node. In the second case, long cycle lengths were produced in the His-Purkinje system due to A-V nodal Wenckebach periods. The long cycles prolonged refractory periods in the His Purkinje system so that subsequent beats (short cycles) were blocked distal to H.The repetitive block of consecutive multiple atrial impulses could result in unexpected degrees of ventricular asystole during usually benign Type I second-degree A-V block.     

Frequency response of fluid-filled catheter-micromanometer systems used for measurement of left ventricular pressure

The resonant frequencies of five commonly used fluid-filled catheters connected to a solidstate microdisplacement pressure gauge were 18 to 33 per cent higher than those obtained with a conventional manometer. Four catheters had a flat amplitude response to 26 Hz. or more at the 10 per cent amplitude distortion level. The dynamic response characteristic of certain fluid-filled catheters used with microdisplacement pressure gauges allows one to record high fidelity left ventricular pressure curves.     

The abnormal heart rate response to a deep breath in borderline labile hypertension: a sign of autonomic nervous system dysfunction

A group of patients with borderline or labile hypertension were prospectively recruited and asked to take a deep breath while lying supine and being monitored by electrocardiography. Their attenuated heart rate responses were sharply abnormal, demonstrating an excessively rapid rate throughout but without quickening on inspiration nor slowing with expiration. It is suggested that this further demonstrates inadequate autonomic control, sympathetic and parasympathetic, of the heart in labile hypertension and even at a moment when the patient's blood pressure is normal.     

Patterns of atrioventricular conduction in children.

In this study, intracardiac electrograms were performed in 20 children--ranging in age from eight months to 18 years and without evidence of conduction disturbances on the scalar electrocardiogram--to determine the normal conduction patterns, response to atrial pacing, and values of refractory periods. Atrial pacing--18 cases--induced a prolongation al AH on increasing heart rates in all; 11 developed Wenckebach block proximal to the bundle of His at the mean pacing rate of 224 per minute +/- 45 (1 S.D.). Refractory periods were shorter than in adults. Study of the pattern of A-V conduction revealed three types of response: (1) the atrium was the limiting structure in 11 cases; (2) the delay occurred in the A-V node only in four cases; and (3) the delay occurred both in the A-V node and His-Purkinje system. This response was observed in one case only.     

Electrocardiographic changes simulating acute myocardial infarction caused by hyperkalemia: report of a patient with normal coronary arteriograms.

A patient is described with severe diabetic ketoacidosis and hyperkalemia who presented with an ECG resembling an acute anterior wall myocardial infarction. Treatment of hyperkalemia resulted in prompt return of the ECG towards normal. Subsequent work-up including exercise testing and selective coronary arteriography ruled out any significant coronary artery disease suggesting that the ECG changes were probably caused by hyperkalemia. While similar changes have rarely been described in the past, this would appear to be the first such case in whom coronary artery disease was ruled out by a negative exercise testing and coronary arteriography.     

Pathologic measurements in aortic atresia

Detailed autopsy measurements were performed in 13 infants with hypoplastic left ventricle and aortic atresia. Emphasis was placed on the evaluation of changes in the right ventricle, since its function may be important in determining surgical survival. Other important aspects were the ascending aortic and transverse aortic arch diameter, the presence of left atrial obstruction, and the size of the left atrium. The development of improved 2DE and Doppler imaging will permit preoperative and sequential evaluation of these parameters. Measurements performed in this study may serve as a basis for selection of infants for palliative surgery; these procedures are being undertaken more frequently in this hitherto fatal lesion. The measurements may also serve as a basis for noninvasive serial studies of these infants postoperatively.     

Bundle branch block. Demonstration of the incomplete nature of some "complete" bundle branch and fascicular blocks by the extrastimulus technique

The incomplete nature of some electrocardiographic “complete” bundle branch and fasclcular blocks is demonstrated using the atrial extrastimulus technique. Patient 1, with a QRS pattern of “complete” left bundle branch block, manifested a QRS pattern of right bundle branch block at a shorter coupling interval, indicating that the left bundle could conduct. Patient 2, with a QRS pattern of right bundle branch block and “complete” left anterior hemiblock, manifested a pattern of left posterior hemiblock at a shorter coupling interval, indicating that the left anterior fascicle could conduct. Patient 3, with a normal QRS complex, showed left bundle branch block at shorter coupling intervals and then a pattern of right bundle branch block as the coupling interval was further decreased, indicating that functional left bundle branch block was incomplete. This demonstration of partial bundle branch block depends on a discordance of conduction time and refractory period, the bundle or fascicle with depressed conduction (incomplete block) having a shorter refractory period than the more normally conducting bundle or fascicle. This discordance may be related to the development of trifascicular block in patients with bifascicular block and a normal H-V interval. It is a predisposing factor in the complex patterns of aberrant conduction seen during supraventricular tachyarrhythmias with varying cycle lengths.     

Estimation of central venous pressure by examination of jugular veins

Attempts were made in 39 seriously ill patients to estimate the central venous pressure (measured through an intrathoracic venous catheter) by clinical examination of the jugular veins. Internal jugular veins were usually not visible. Inspection of the external jugular veins resulted in 103 measurements. These correlated poorly with the actual CVP, since only 47 per cent of the pooled observations were within 2 cm. of the recorded value. To obtain a 90 per cent coincidence, an error of up to 4 cm. had to be allowed. Moreover, large discrepancies were noted in individual cases. The central venous pressure cannot be reliably estimated by inspection of the jugular veins.