Canad. Med. Ass. J. 1340 Chabot and others: Vectorcardiographic Evaluation Dec. 25,1965, vol. 9J Vectorcardiographic Evaluation of Postoperative Changes in Patients with Interatrial Septal Defect: A Review of 55 Cases M. CHABOT, M.D.,* A. KARAMEHMET, M.D.,t M. BOURASSA, M.D. and P. DAVID, M.D.,$ Montreal ABSTRACT SOMMAIRE The pre- and post-operative vectorcardio- Nous avons etudie les vectocardiogrammes of 55 with atrial septal defect de 55 patients souffrant d'un defaut de la grams patients avant et l'o¬ (ASD) are discussed. Forty-nine were of cloison interauriculaire, apres ostium secundum type and six of ostium peration. Quarante-neuf cas etaient des primum type. The criteria used to study defauts de type ostium secundum et six cas the of ventricular de type ostium primum. Dans le plan hori¬ regression right hyper¬ des forces trophy were: in the horizontal plane, the zontal les rapports anterieures/ ratio of anterior-over-posterior forces, the posterieures et droites/gauches, ainsi que right-over-left forces and the rotation of les variations du sens de rotation nous ont the body of the QRS loop; in the frontal servi de criteres pour apprecier la regression plane, the direction of half-area vector. Us¬ de Thypertrophie droite. Dans le plan fron¬ ing these criteria, 46 out of 49 patients with tal, la direction du vecteur de demi-surface defects of the ostium secundum type had fut le critere utilise. vectorcardiographic evidence of regression Chez les 49 malades porteurs d'une ano- of right ventricular hypertrophy. Marked malie de type secundum, 46 montrerent clinical improvement was also demonstrated une regression de Thypertrophie ventri¬ in all these patients. The three patients in culaire droite au vectocardiogramme. A ces whom was not demonstrated donnees vectorielles correspondait une ame- improvement Chez trois on the vectorcardiogram had persistence of lioration clinique significative. non il a cardiac defect. Following surgery two patients ameliores vectoriellement, y children with ostium defects avait persistance d'anomalie cardiaque. primum d'un de showed no change in the frontal plane, Chez deux enfants porteurs defaut whereas in the horizontal plane a normali- type ostium primum, nous avons observe zation of vectorial forces was observed. peu de changement dans le plan frontal malgre une normalisation du plan hori¬ zontal. and vectorcardio¬ ELECTROCARDIOGRAPHICgraphic studies of the depolarization process of the heart clues to the cardiovascular dynamics tend to return to normal, may provide important the anatomic due to IASD ven¬ diagnosis of the anatomical lesion underlying many changes (right cardiac defects. Cardiac catheterization tricular hypertrophy or dilatation) are also ex¬ congenital to toward normal.1' 3 The VCG has and corrective surgery have also afforded the op- pected regress portunity for correlation of the electric, hemody¬ been advocated as a simple method to determine namic and anatomic findings in patients with these the adequacy of closure of the defect. defects. The of the electrical The purpose of this report is to evaluate the cor¬ diagnostic importance relation of with phenomena, especially in cases of interatrial septal the vectorcardiographic changes defect (IASD) of both the secundum and primum the clinical improvement observed after surgical a with has been demonstrated by many authors. In correction in group of patients interatrial types, defect studied at the Montreal Heart In¬ a recent publication, the vectorcardiogram (VCG) septal was reported to give more information than the stitute. standard 12-lead electrocardiogram (ECG): in some cases of IASD in which the ECG was con¬ Material sidered, on reasonable grounds, to be within normal The files of patients who had had a vector¬ limits, the presence of the lesion was suggested by cardiogram before and after surgical correction of the VCG.11 After surgical correction, when the IASD were reviewed. There were 55 such cases, and in all the diagnosis was confirmed by hemo¬ From the Montreal Heart Institute, 5415 Blvd. de TAssomp¬ tion, Montreal 36, P.Q. dynamic studies and at surgery. Patients with ac- ?Chief. Department of Electrocardiography and Vector- cardiography, Montreal Heart Institute. companying defects such as coarctation of the tPresent address: Hacettepe Medical Center, Ankara, interventricular aortic valve Turkey. aorta, septal defect, $Director, Montreal Heart Institute. disease, patent ductus arteriosus or pulmonic ste- Canad. Med. Ass. J. AND OTHERS: VECTORCARDIOGRAPHIC EVALUATION 1341 Dec. 25, 1965, vol. 93 CHABOT nosis were excluded. Forty-nine patients had de¬ fects of the "secundum" type and six had defects of the "primum" type. Thirty-six cases of ostium secundum were uncomplicated; nine also had par¬ tial anomalous pulmonary venous return, one mitral stenosis, two minimal mitral insufficiency and one an unruptured aneurysm of the sinus of Valsalva. The ostium secundum group consisted of 40 females and nine males. There were two females and four males in the ostium primum group. The age of the patients ranged from 4 to 44 years when the first (preoperative) VCG was taken (Fig. 1). A FORCES T0 THE RIGHT NUMBER B FORCES T0 THE LEFT OF CASES C ANTERIOR FORCES D POSTERIOR FORCES Fig. 2..Measure of the anterior, posterior, right and left forces (see text for detail.) the postoperative VCG a decrease of more than 20% over the initial value of this ratio is considered as indicative of improvement. 2. The X axis (right-left) is also determined on the horizontal plane. From two points most an¬ teriorly and posteriorly on the QRS loop, perpen¬ 4-9 10-19 20-29 30-39 >40 years diculars are drawn to the X axis. Anterior and OSTIUM SECUNDUM OSTIUM PRIMUM posterior forces and their ratio are calculated in the Fig. 1..Distribution of patients according" to age. same way. A decrease of more than 20% over the preoperative value is considered indicative of im¬ The VCG's were recorded between provement. postoperative 3. With to the direction of of two weeks and six after most of respect inscription years surgery, a from them taken between six months and the loop in the horizontal plane, change (49) being clockwise to or from two 15 had more figure-of-eight configuration, years postoperatively; patients figure-of-eight to counterclockwise, is considered than one postoperative VCG study. indicative of were taken with a Sanborn vector improvement. The VCG's 4. In the frontal the half-area vector is and and recorded with a plane amplifier visoscope, measured. A shift to the left of more than 30° Technica camera on Kodak Super Panchro-press is considered indicative of 4 x 5 inch film. The cube reference improvement. (This type B, system criterion was suitable in cases of ostium secundum of Grishman was utilized. The beam was inter¬ 400 times the rounded end of only.) rupted per second, these four we classified the tear drops indicating the direction of inscription Using criteria, degree of the of improvement shown in the postoperative VCG's loop. as or under vision was 0, +, ++, +++, ++++. Surgical correction direct per¬ of the inferior and forces did formed in all cases by Drs. Pierre Grondin, Gilles Study superior Lepage and Jean-Louis Lamy. not show any significant change; the maximum vector in the frontal plane had a large scatter, and Methods the deviation after surgery was also not significant. Though they were measured in each case, these Four criteria were used to determine the re¬ parameters were not included in the study. gression of the right ventricular hypertrophy: 1. The Z axis (anteroposterior) is determined on Results the horizontal From two situated maxi¬ plane. points Ostium Secundum mum to the right and maximum to the left on the QRS loop, perpendiculars to this axis are drawn 1. The average of right over left forces decreased (Fig. 2). Forces to the right and forces to the left from 0.93 to 0.32 (Table I) after surgery. Forty- are measured (in mv.) and the ratio of forces two of 49 cases presented a decrease of more than to the right to forces to the left is calculated. In 20%; six showed no change or a change of less than Canad. Med. Ass. J. 1342 Chabot and others: Vectorcardiographic Evaluation Dec. 25, 1965, vol. 93 TABLE I..Ostium Secundum 4. The mean of half-area vectors in the frontal Forces to right (mr.) Forces to left (mv.) Right/left plane was 97° before surgery (15-220°). Following Before After Before After Before After the was the Average. 0.59 0.25 0.91 1.01 0.93 0.32 surgery, average 38°, range varying Range.0.15-2.70 0.03-0.50 0.27-2.10 0.56-2.14 0.16-3.84 0.03-1.83 from 335° to 105° (Fig. 5). In 32 patients the half- Anterior forces (mv.) Posterior forces (mv.) Ant./post. area vector had shifted to the left more than 30°. Before After Before After Before AfUr There was no shift to the right after surgery (Fig. Average. 0.73 0.44 0.14 0.17 3.96 2.64 4). Range.0.12-2.12 0.06-1.40 0-0.87 0-0.68 0.47-9.30 0.40-9.50 oo in 19 °° in 7 cases cases 20% ; and only one patient presented a negative re¬ sult, i.e. augmentation of the forces to the right after surgery. He was noted to have a systolic murmur at the left sternal border during the early post¬ operative period. Unfortunately he was lost to follow-up, and a further control study could not be obtained. 2. The average of anterior over posterior forces decreased from 3.96 to 2.64 after surgery. The ratio of anterior forces was equal to infinity in 19 cases before surgery and in seven after surgery.