Right Axis Deviation Research Articles

Intraventricular conduction time in patients with bundle branch block

Summary His bundle electrograms (HBE) were recorded in 61 patients with various intraventricular conduction abnormalities. Seventeen patients also underwent right atrial pacing at various rates. Forty-six patients had a pattern of right bundle branch block (RBBB) and left axis deviation (LAD) (Group I). Five patients had RBBB with normal frontal plane axis (Group II). Left bundle branch block (LBBB) was the only conduction abnormality in six patients (Group III), and RBBB with right axis deviation (RAD) was present in four patients (Group IV). Intraventricular conduction time (H-Q interval) was recorded in each patient during supraventricular conduction. Eleven patients showed spontaneous Mobitz type II second degree atrioventricular (A-V) block or complete heart block (CHB) either before, during or subsequent to the study. In ten of these the H-Q interval was prolonged during orthograde conduction. Atrial pacing produced second degree A-V block distal to the His bundle potential in three patients with prolonged H-Q interval. Two of these had earlier shown transient CHB while the third developed CHB subsequently. It is concluded that the majority of patients with bundle branch block who show Mobitz type II or CHB have prolonged H-Q interval during supraventricular conduction. Atrial pacing may occasionally produce block distal to the His bundle in patients with prolonged H-Q interval.

Gross anatomy associated with patterns called left posterior hemiblock.

From a compilation of 1411 gross dissections of the hearts from patients who had had recent electrocardiograms prior to death, 62 were found to have frontal QRS axes between +90 and +180°. Thirty-eight exhibited an S 1 Q 3 R 3 pattern-the second screening criterion basic to consideration for the label of left posterior hemiblock (LPH). Twenty-two of these also had right ventricular free wall weights in excess of 70 g. Two others exhibited inferior myocardial infarction only. Of the remaining 14, six afforded mild clinical suspicion of increased hemodynamic loading of the right heart but did not have increased right ventricular weights. Four had right bundle-branch block (RBBB), and only one had a prolonged P-R interval. The S 1 Q 3 R 3 pattern with right-axis deviation thus occurred in patients with or without right ventricular hypertrophy and with or without inferior wall myocardial infarction. Right bundle-branch block was a frequent occurrence in the spectrum of right-axis deviation (RAD) whether S 1 Q 3 R 3 was present or not. The scatter of the frequent associates of RAD-inferior myocardial lesions, right ventricular hypertrophy, a clinical history of right ventricular loading diseases, and RBBB—suggests three alternative ways of viewing the S 1 Q 3 R 3 pattern with RAD: (1) LPH is a cause of S 1 Q 3 R 3 with RAD. It is a manifestation of left ventricular myocardial disease, but it may be a result of overt infarction, or may be mimicked by right ventricular disease. (2) LPH is the cause of S 1 Q 3 R 3 with RAD. It is the means by which diverse etiologies produce a distinctive electrocardiographic pattern (including left ventricular myocardial deficits, right ventricular enlargement, or a small group of unknown causes). (3) LPH is an artifact of convenience. Patients with RAD may or may not have S 1 Q 3 R 3 ; they frequently have inferior wall myocardial infarction, right ventricular overload or enlargement, and RBBB.

Left anterior hemiblock and right bundle branch block before and after surgical repair of tetralogy of Fallot

The preoperative ECG was studied in 217 patients who underwent total surgical correction of uncomplicated tetralogy of Fallot and the effects of surgery were observed in 160 of these cases. Analysis of the incidence of LAH, RBBB, and the combination of these conduction defects revealed that these were universally absent in the preoperative tracings; their presence should therefore suggest the possibility of an unusual variety of VSD or an associated malformation. RBBB was induced surgically in 84 per cent, and the combination of RBBB and LAH was induced surgically in 7 per cent of cases. In LAH the mid-vector was located at −30° or further to the left, and in the majority of cases the 0.02 second vector was located at +120°, producing q waves in Leads I and aV L. Preoperatively, 10 per cent of the tracings showed the presence of small q waves in Leads I and aV L in the presence of right axis deviation (RAD) and it has been previously suggested that this represents a minor degree of LAH. Our data would lend credence to this possibility, because surgically induced LAH occurred in 31 per cent of these cases and in only 4 per cent of the cases where these findings were absent. In the patients with surgically induced LAH, evidence of a minor degree of LAH was present in half of these cases before operation.

Right bundle branch block with normal, left or right axis deviation: Analysis by his bundle recordings

His bundle (BH) electrograms were recorded in 123 patients. The electrocardiogram showed only left axis deviation (LAD) in ten, right bundle branch block (RBBB) with a normal axis in thirty, RBBB and LAD with or without old myocardial infarction in sixty-eight and RBBB with right axis deviation (RAD) in fifteen. Thirteen of these patients were restudied at intervals of six months to two years. The conduction times through the atrioventricular (A-V) node (A-H) and His-Purkinje system (H-V) were measured during normal sinus rhythm and atrial pacing. In all but four patients with sinus rhythm in whom second degree A-V block developed only during atrial pacing at rapid rates (range 100 to 180/minute) the block was localized in the A-H interval (A-V node). In the other four with sinus rhythm the second degree block was localized distal to the BH deflection (H-V). Most of the patients with RBBB (normal axis) and first degree A-V block had a normal H-V time with delay localized in the A-V node (A-H), indicating that this combination in the electrocardiogram does not necessarily mean bilateral bundle branch block. In none of the ten patients with only LAD was the H-V time abnormal (normal range = 35 to 45 msec). In seven (23 per cent) of the thirty patients with RBBB (normal axis) the H-V time was abnormal. Forty-nine (72 per cent) of the sixty-eight patients with RBBB and LAD with or without myocardial infarction had an abnormal H-V time. Furthermore, patients with similar electrocardiographic patterns (RBBB and LAD) may or may not have an abnormal H-V time. All fifteen patients (100 per cent) with RBBB and RAD had abnormal H-V times. This study demonstrates that (1) the surface electrocardiographic criteria for assessing quantitative damage in the His-Purkinje system are frequently of limited value, and (2) the majority of the patients (72 per cent) with RBBB and LAD, besides RBBB and anterior hemiblock, have additional damage in the remaining fascicles of the His-Purkinje system. This would suggest partial bilateral bundle branch block or trifascicular block.

Histological studies on the conduction system in 14 cases of right bundle branch block associated with left axis deviation.

Sixteen cases (10 men and 6 women of 71 to 88 years of age) of complete right bundle branch block (RBBB) with right axis deviation (RAD) were examined for the conduction system. There were 7 cases of hypertension, 2 myocardial infarction and 6 pulmonary disease. The electrical axis was from +90°to +150°with an average of +113°, and small q waves in leads II, III, and aVF were present in 11 cases. Duration of RBBB with RAD was within 2 months in 4 cases and over 1 year in 12. There was only 1 case who developed complete atrioventricular (AV) block.Heart weight was from 220 to 445Gm with an average of 306Gm. Severe coronary sclerosis was found in 6 cases and myocardial infarction in 2. The AV node and the penetrating portion of the AV bundle showed only slight fibrosis, but the branching portion of the AV bundle showed moderate degeneration and fibrosis. Right bundle branch (RBB) was interrupted with fibrosis at the 1st portion in 7, 2nd portion in 8 and 3rd portion in 1. Complete interruption was found in 57 to 100% (average 87%) of the left posterior fascicles (LPF) and in 0 to 100% (average 28%) of the left anterior fascicles (LAF). It was concluded that the RBBB with RAD was produced by interruption of RBB and LPF.

Congenital Deficiency of the Pericardium

Deficiency of the parietal pericardium was demonstrated in seven patients at the Mayo Clinic. The defect was left-sided in all seven and large in five of the six patients who underwent thoracotomy. Diagnosis was established in one case by the demonstration of pneumopericardium after artificial pneumothorax was made for that purpose. Six of the group were male. In five patients without heart disease, the electrocardiogram revealed right-axis deviation and late development of the R deflection in precordial leads. The electrocardiogram may be of value in the diagnosis of congenital pericardial deficiency.