Development of a patient-oriented Hololens application to illustrate the function of medication after myocardial infarction

Aims

Statin treatment is one of the hallmarks of secondary prevention after myocardial infarction. Adherence to statins tends to be difficult and can be improved by patient education. Novel technologies such as mixed reality (MR) expand the possibilities to support this process. To assess if an MR medication-application supports patient education focused on function of statins after myocardial infarction.

Methods and results

A human-centred design-approach was used to develop an MR statin tool for Microsoft HoloLens™. Twenty-two myocardial infarction patients were enrolled; 12 tested the application, 10 patients were controls. Clinical, demographic, and qualitative data were obtained. All patients performed a test on statin knowledge. To test if patients with a higher tendency to become involved in virtual environments affected test outcome in the intervention group, validated Presence- and Immersive Tendency Questionnaires (PQ and ITQ) were used. Twenty-two myocardial infarction patients (ST-elevation myocardial infarction, 18/22, 82%) completed the study. Ten out of 12 (83%) patients in the intervention group improved their statin knowledge by using the MR application (median 8 points, IQR 8). Test improvement was mainly the result of increased understanding of statin mechanisms in the body and secondary preventive effects. A high tendency to get involved and focused in virtual environments was moderately positive correlated with better test improvement (r = 0.57, P < 0.05). The median post-test score in the control group was poor (median 6 points, IQR 4).

Conclusions

An MR statin education application can be applied effectively in myocardial infarction patients to explain statin function and importance.

Optical Coherence Tomography: Current Applications for the Assessment of Coronary Artery Disease and Guidance of Percutaneous Coronary Interventions

INTRODUCTION

Coronary angiography (CAG) is the standard modality for assessment of coronary stenoses and intraprocedural guidance of percutaneous coronary interventions (PCI). However, the limitations of CAG are well recognized. Intracoronary imaging (ICI) can potentially overcome these limitations. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are the main ICI techniques utilized in clinical practice.

AIM

This narrative literature review addresses the current clinical applications of OCT in relation to IVUS and CAG in patients with coronary artery disease (CAD). Items reviewed are: technical implications of OCT and IVUS, lesion characterization and decision-making, stent optimization criteria, post-stenting results, safety in terms of procedural complications, clinical outcomes, and indications.

MAIN FINDINGS

OCT is able to reveal more detail than IVUS due to its higher resolution. However, this higher resolution comes at the cost of a lower penetration depth. Pre-stenting OCT results in procedural change in more than 50% of the cases in terms of stent length and diameter. Post-stenting OCT resulting in stent optimization is reported in at least 27% of the cases. Malapposition and under-expansion are treated with post-dilatations, while edge dissections are treated with additional stent placement. Stent expansion, stent apposition, distal stent edge dissections, and reference lumen areas seem to be the most important stent optimization criteria for both decision-making and for reducing the risk of adverse events during follow-up. Both OCT and IVUS are superior in terms of post-stenting results compared with CAG alone. However, there is no consensus about whether OCT guidance results in better stent expansion than IVUS guidance. OCT, IVUS, and CAG are safe procedures with few reported procedural complications. In general, OCT guidance seems to contribute to favorable clinical outcomes compared with CAG guidance only. However, OCT guidance results in similar clinical outcomes as with IVUS guidance. OCT could be considered for lumen assessment and stent-related morphology in more complex cases in which CAG interpretation remains uncertain. Since OCT and IVUS have distinct characteristics, these techniques are complementary and should be considered carefully for each patient case based on the benefits and limitations of both techniques.

Perspectives of Patients and Professionals on Information and Education After Myocardial Infarction With Insight for Mixed Reality Implementation: Cross-Sectional Interview Study

BACKGROUND

Patient education is crucial in the secondary prevention of cardiovascular disease. Novel technologies such as augmented reality or mixed reality expand the possibilities for providing visual support in this process. Mixed reality creates interactive digital three-dimensional (3D) projections overlaying virtual objects on the real-world environment. While augmented reality only overlays objects, mixed reality not just overlays but anchors virtual objects to the real world. However, research on this technology in the patient domain is scarce.

OBJECTIVE

The aim of this study was to understand how patients perceive information provided after myocardial infarction and examine if mixed reality can be supportive in this process.

METHODS

In total, 12 patients that experienced myocardial infarction and 6 health care professionals were enrolled in the study. Clinical, demographic, and qualitative data were obtained through semistructured interviews, with a main focus on patient experiences within the hospital and the knowledge they gained about their disease. These data were then used to map a susceptible timeframe to identify how mixed reality can contribute to patient information and education.

RESULTS

Knowledge transfer after myocardial infarction was perceived by patients as too extensive, not personal, and inconsistent. Notably, knowledge on anatomy and medication was minimal and was not recognized as crucial by patients, whereas professionals stated the opposite. Patient journey analysis indicated the following four critical phases of knowledge transfer: at hospital discharge, at the first outpatient visit, during rehabilitation, and during all follow-up outpatient visits. Important patient goals were understanding the event in relation to daily life and its implications on resuming daily life. During follow-up, understanding physical limitations and coping with the condition and medication side effects in daily life emerged as the most important patient goals. The professionals' goals were to improve recovery, enhance medication adherence, and offer coping support.

CONCLUSIONS

There is a remarkable difference between patients' and professionals' goals regarding information and education after myocardial infarction. Mixed reality may be a practical tool to unite perspectives of patients and professionals on the disease in a more even manner, and thus optimize knowledge transfer after myocardial infarction. Improving medication knowledge seems to be a feasible target for mixed reality. However, further research is needed to create durable methods for education on medication through mixed reality interventions.

An initial exploration of subtraction electrocardiography to detect myocardial ischemia in the prehospital setting

Background

Methods

Results

Conclusions

Expectations and perceived barriers to widespread implementation of e‑Health in cardiology practice: Results from a national survey in the Netherlands

INTRODUCTION

Expectations of physicians concerning e‑Health and perceived barriers to implementation in clinical practice are scarcely reported in the literature. The purpose of this study was to assess these aspects of cardiovascular e‑Health.

METHODS

A survey was sent to members of the Netherlands Society of Cardiology. In total, the questionnaire contained 30 questions about five topics: personal use of smartphones, digital communication between respondents and patients, current e‑Health implementation in clinical practice, expectations about e‑Health and perceived barriers for e‑Health implementation. Age, personal use of smartphones and professional environment were noted as baseline characteristics.

RESULTS

In total, 255 respondents filled out the questionnaire (response rate 25%); 89.4% of respondents indicated that they considered e‑Health to be clinically beneficial, improving patient satisfaction (90.2%), but also that it will increase the workload (83.9%). Age was a negative predictor and personal use of smartphones was a positive predictor of having high expectations. Lack of reimbursement was identified by 66.7% of respondents as a barrier to e‑Health implementation, as well as a lack of reliable devices (52.9%) and a lack of data integration with electronic medical records (EMRs) (69.4%).

CONCLUSION

Cardiologists are in general positive about the possibilities of e‑Health implementation in routine clinical care; however, they identify deficient data integration into the EMR, reimbursement issues and lack of reliable devices as major barriers. Age and personal use of smartphones are predictors of expectations of e‑Health, but the professional working environment is not.

Long-term outcome after atrial correction for transposition of the great arteries

Objective

This study assessed adult survival and morbidity patterns in patients who underwent atrial correction according to Mustard or Senning for transposition of the great arteries (TGA).

Methods

In 76 adult patients with TGA (59% male) after atrial correction, long-term survival and morbidity were investigated in three periods: early (<15 years postoperatively), midterm (15–30 years postoperatively) and late (>30 years postoperatively).

Results

The Mustard technique was performed in 41 (54%) patients, and the Senning technique was performed in 35 (46%) patients aged 3.1 (IQR: 2.1–3.8) and 1.0 (IQR: 0.6–3.1; p<0.01) years, respectively. Adult survival was 82% at 39.7 (IQR: 35.9–42.4) years postoperatively and exceeded 50 years in four patients. Supraventricular tachycardia (SVT) occurred in 51% of patients. The incidences of ventricular arrhythmia (0%, 8% and 13%; p<0.01), heart failure (0%, 5% and 19%; p<0.01) and surgical reinterventions (0%, 5% and 11%; p=0.01) increased from early to late follow-up. At last follow-up, RV function was depressed in 31 (46%) patients, and New York Heart Association functional class was ≥2 in 34 (48%) patients. Bradyarrhythmia, SVT and ventricular arrhythmia were associated with depressed RV function (OR: 4.47, 95% CI 1.50 to 13.28, p<0.01; OR: 3.74, 95% CI 1.26 to 11.14, p=0.02; OR: 14.40, 95% CI 2.80 to 74.07, p<0.01, respectively) and worse functional capacity (OR: 2.10, 95% CI 0.75 to 5.82, p=0.16; OR: 2.87, 95% CI 1.06 to 7.81, p=0.04; OR: 8.47, 95% CI 1.70 to 42.10, p<0.01, respectively).

Conclusions

In adult patients with TGA, survival was 82% at 39.7 (IQR: 35.9–42.4) years after atrial correction. Morbidity was high and included SVT as most frequent adverse event. Ventricular arrhythmias, heart failure and surgical reinterventions were common during late follow-up. Adverse events were associated with depressed right ventricle function and reduced functional class.

Short-term career perspectives of young cardiologists in the Netherlands

Background

Since it was anticipated that the need for doctors would increase due to demographic changes, the number of positions for medical specialty training programs has increased from the year 2000 onwards. However, the number of permanent positions for young cardiologists did not follow that trend leading to concerns about future employment. Therefore, the aim of the current study was to assess short-term career perspectives of young cardiologists in the Netherlands.

Methods

All cardiologists who ended their training between 1 January 2011 and 31 December 2014 were invited to fill in a questionnaire about their first employment status and were followed yearly until the participant had a permanent position. The timespan between the end of training and the moment of permanent employment was assessed. Furthermore, the association between professional profile and short-term career perspectives was investigated.

Results

The observed unemployment was 1.6% and lasted less than a year in all cases. Of the participants, 77% started their career with a temporary contract; within four years this was 7%. Of young cardiologists, 46% started their career as a fellow and 24% as an attending physician. A total of 29% of male cardiologists started their career with a permanent contract as compared with 12% of females (p = 0.01). Within two years this difference was no longer observed.

Conclusions

Unemployment is low among young cardiologists. Most cardiologists start their career with a temporary contract. The time to a permanent contract is slightly longer for female cardiologists as compared with males.

Detection of elevated pulmonary pressures by the ECG-derived ventricular gradient: A comparison of conversion matrices in patients with suspected pulmonary hypertension

BACKGROUND

The aim was to assess the diagnostic value of the Inverse Dower (INVD)-derived vectorcardiogram (VCG) and the Kors-derived VCG to detect elevated systolic pulmonary artery pressure (SPAP) in suspected pulmonary hypertension (PH).

METHODS

In 132 patients, morphologic variables were evaluated by comparing the VCG parameters synthesized by INVD and Kors matrix. Comparison of the diagnostic accuracy of detecting SPAP ≥50mmHg between the matrices was performed by ROC curve analysis and logistic regression analysis.

RESULTS

Most VCG parameters differed significantly between INVD and Kors. ROC analysis for detection of SPAP ≥50mmHg by VG projected on the X-axis demonstrated no difference (p=0.99) between INVD (AUC=0.80) and Kors (AUC=0.80). Both the INVD- and Kors-derived VCG provided significant diagnostic information on the presence of SPAP ≥50mmHg (INVD, OR 1.05, 95%CI 1.03-1.07; P<0.001; Kors, OR 1.05, 95%CI 1.03-1.08; P<0.001).

CONCLUSION

Although there were significant differences in measures of vector morphology, both INVD- and Kors-derived VCG demonstrated equal clinical performance in case of elevated SPAP.

Follow-up after tricuspid valve surgery in adult patients with systemic right ventricles

OBJECTIVES

In patients with congenitally corrected transposition of the great arteries (ccTGA) or after atrial (Mustard or Senning) correction for transposition of the great arteries (acTGA), the right ventricle (RV) supports the systemic circulation. The tricuspid valve (TV) (systemic atrioventricular valve) is prone to regurgitation in these patients and this is associated with impending RV failure and decreased survival. This study evaluates mid-term functional improvements, echocardiographic findings and survival after TV surgery in this patient group.

METHODS

From July 1999 to November 2014, 26 patients (mean age 37.1 ± 12.3 years, 14 females) with ccTGA (n = 15) or acTGA (n = 11) had TV surgery. All patients had RV dysfunction and more-than-moderate TV regurgitation (TR); 14 underwent TV replacement (TVR) and 12 had valvuloplasty (TVP). Main outcomes were New York Heart Association (NYHA) functional class, TR and RV dysfunction at 1 year postoperatively and at latest follow-up. Complications and freedom from the composite end-point of death or recurrent TR were analysed.

RESULTS

The median follow-up time was 5.9 years (range, 0-16.1 years). Mean NYHA functional class significantly improved to 1.7 [95% confidence interval (CI): 1.3-2.1] at 1 year (P= 0.004) and was 2.1 (95% CI: 1.7-2.6) at latest follow-up (P= 0.14). TV competence significantly improved to a mean TR grade of 1.1 (95% CI: 0.5-1.7) at latest follow-up (P< 0.001). The mean grade for RV function at latest follow-up was 2.7 (95% CI: 2.3-3.0). Most encountered postoperative complications were arrhythmias and temporary haemodynamic instability due to low cardiac output. Early mortality was 11.5% (n = 3); late mortality was 15.4% (n = 4). Estimated freedom from the composite end-point of death or recurrent TR was 76.9% (95% CI: 55.7-88.9%) at 1 year and 64.8% (95% CI: 43.2-79.9%) at 5 years. In TVP patients, TV function at 1 year and at latest follow-up was significantly worse than in TVR patients (P< 0.001 and P= 0.003, respectively). Also, TVP patients had a significantly lower composite end-point survival curve compared with TVR patients (P= 0.018).

CONCLUSIONS

In this patient group, TV surgery showed stabilization of RV function and improvement of NYHA functional class for at least several years. In this series, TVR appears superior to TVP with respect to occurrence of recurrent TR. Early and late mortality after TV surgery is substantial, and we believe that patients with significant TR should be referred earlier for surgery for better outcome.

Electrocardiographic detection of pulmonary hypertension in patients with systemic sclerosis using the ventricular gradient

BACKGROUND

Pulmonary hypertension (PH) is a leading cause of death in systemic sclerosis (SSc) patients. The current study assessed the ability of the ECG-derived ventricular gradient (VG-RVPO) to detect PH and predict all-cause mortality in PH patients with subtypes of SSc differing in the extent of multi-organ involvement.

METHODS

ECGs were obtained from 196 patients with limited and 77 patients with diffuse SSc included from our screening programme on cardiac complications. The association of the VG-RVPO with (1) the presence of PH, (2) conventional screening parameters and (3) survival in PH patients was assessed.

RESULTS

In limited SSc patients an elevated VG-RVPO corresponded with the presence of PH (-5±12 mV.ms vs -22±16 mV.ms, P<0.01), correlated significantly with conventional screening parameters and had a better diagnostic performance than the presence of a right heart axis (AUC 0.81 vs 0.60; P=0.04). These differences were not observed in patients with diffuse SSc. An elevated VG-RVPO was associated with decreased survival in all SSc patients with PH (3 year survival 30% vs 64%, P=0.02).

CONCLUSION

An elevated VG-RVPO is associated with PH in limited SSc patients and with decreased survival in all SSc patients with PH.

Prognostic value of right ventricular longitudinal peak systolic strain in patients with pulmonary hypertension

BACKGROUND

Right ventricular (RV) function is an important prognostic marker in patients with pulmonary hypertension. The present evaluation assessed the prognostic value of RV longitudinal peak systolic strain (LPSS) in patients with pulmonary hypertension.

METHODS AND RESULTS

A total of 150 patients with pulmonary hypertension of different etiologies (mean age, 59±15 years; 37.3% male) were evaluated. RV fractional area change and tricuspid annular plane systolic excursion index were evaluated with 2-dimensional echocardiography. RV LPSS was assessed with speckle-tracking echocardiography. The patient population was categorized according to a RV LPSS value of -19%. Among several clinical and echocardiographic parameters, the significant determinants of all-cause mortality were evaluated. There were no significant differences in age, sex, pulmonary hypertension cause and left ventricular ejection fraction between patients with RV LPSS <-19% and patients with RV LPSS ≥-19%. However, patients with RV LPSS ≥-19% had significantly worse New York Heart Association functional class (2.7±0.6 versus 2.3±0.8; P=0.003) and lower tricuspid annular plane systolic excursion (16±4 mm versus 18±3 mm; P<0.001) than their counterparts. During a median follow-up of 2.6 years, 37 patients died. RV LPSS was a significant determinant of all-cause mortality (HR, 3.40; 95% CI, 1.19-9.72; P=0.02).

CONCLUSIONS

In patients with pulmonary hypertension, RV LPSS is significantly associated with all-cause mortality. RV LPSS may be a valuable parameter for risk stratification of these patients. Future studies are needed to confirm these results in the pulmonary hypertension subgroups.

Morphogenesis of outflow tract rotation during cardiac development: the pulmonary push concept

BACKGROUND

Understanding of cardiac outflow tract (OFT) remodeling is essential to explain repositioning of the aorta and pulmonary orifice. In wild type embryos (E9.5-14.5), second heart field contribution (SHF) to the OFT was studied using expression patterns of Islet 1, Nkx2.5, MLC-2a, WT-1, and 3D-reconstructions. Abnormal remodeling was studied in VEGF120/120 embryos.

RESULTS

In wild type, Islet 1 and Nkx2.5 positive myocardial precursors formed an asymmetric elongated column almost exclusively at the pulmonary side of the OFT up to the pulmonary orifice. In VEGF120/120 embryos, the Nkx2.5-positive mesenchymal population was disorganized with a short extension along the pulmonary OFT.

CONCLUSIONS

We postulate that normally the pulmonary trunk and orifice are pushed in a higher and more frontal position relative to the aortic orifice by asymmetric addition of SHF-myocardium. Deficient or disorganized right ventricular OFT expansion might explain cardiac malformations with abnormal position of the great arteries, such as double outlet right ventricle.

Diagnosis and mortality prediction in pulmonary hypertension: the value of the electrocardiogram-derived ventricular gradient

PURPOSE

The aim of this study was to investigate the use of the electrocardiogram-derived ventricular gradient, projected on the x-axis (VGx), for detection of pulmonary hypertension (PH) and for prediction of all-cause mortality in PH patients.

METHODS

In patients referred for PH screening (n = 216), the VGx was calculated semiautomatically from the electrocardiogram and was defined as abnormal when less than 24 mV · ms. The VGx of PH patients was compared with the VGx of patients without PH. The association between a reduced VGx and mortality was investigated in PH patients.

RESULTS

Patients with PH (n = 117) had a significantly reduced VGx: 14 ± 27 vs 45 ± 23 mV · ms, P < .001. Furthermore, a severely reduced VGx (<0 mV · ms) was associated with increased mortality in PH patients: hazard ratio, 1.025 (95% confidence interval, 1.006-1.045; P = .012) per mV·ms VGx decrease.

CONCLUSION

Reduced VGx is associated with the presence of PH and, more importantly, within PH patients, a severely reduced VGx predicts mortality.

Biventricular performance in patients with marfan syndrome without significant valvular disease: comparison to normal subjects and longitudinal follow-up

BACKGROUND

The presence and progressive nature of primary myocardial involvement in Marfan syndrome are debated. The aim of this study was to evaluate the clinical relevance of left ventricular (LV) and right ventricular (RV) strain in adult patients with Marfan syndrome without significant valvular disease.

METHODS

Adult patients with Marfan syndrome (n = 50; mean age, 35.2 ± 12.9 years) were followed prospectively. Echocardiography was performed annually and consisted of comprehensive assessment of ventricular and valvular function. Using speckle-tracking imaging, the baseline strain values of the Marfan population were calculated and compared with the values of normal controls. The follow-up evaluations were used to assess changes in ventricular strain. The association between the incidence of adverse events (heart failure, [supra]ventricular arrhythmias, and proximal aorta surgery) and baseline strain values was investigated.

RESULTS

Compared with controls, patients with Marfan syndrome had significantly lower peak longitudinal LV strain (-18.9 ± 2.3% vs -20.1 ± 1.9%, P < .01) and RV strain (±26.9 ± 5.2% vs ±29.3 ± 4.25%, P < .01). The absolute changes in LV longitudinal, radial, and circumferential strain and RV longitudinal strain during a median 4 years of follow-up were 0.1 ± 2.8%, 1.12 ± 7.6%, 0.3 ± 3.7%, and 0.9 ± 5.5%, respectively, which was not statistically significant. Cox regression demonstrated that reduced LV or RV strain was not associated with adverse outcome (supraventricular arrhythmias, n = 3; proximal aorta surgery, n = 4).

CONCLUSIONS

This study suggests that patients with Marfan syndrome show lower ventricular strain and strain rate values compared with healthy controls. However, no relevant changes in LV and RV function occurred during midterm follow-up in patients with Marfan syndrome without valvular disease at baseline. Although ventricular strain and strain rate were mildly reduced in patients with Marfan syndrome, this did not affect outcomes negatively in the present study.

Clinical value of myocardial perfusion scintigraphy as a screening tool in liver transplant candidates

A cardiac evaluation before orthotopic liver transplantation (OLT) is imperative. Previous investigations have demonstrated that mild to moderate reversible perfusion defects on myocardial perfusion scintigraphy (MPS) in general are associated with a low risk for perioperative cardiac events. The objective of this study was to assess any perfusion defects in consecutive patients with chronic liver disease who were undergoing OLT. OLT candidates underwent extensive cardiovascular screening that included, among other methods, MPS. Patients who had no contraindications for surgery and underwent OLT were followed up. The occurrence and risk of complications and mortality were compared in 3 groups of patients: patients with normal MPS results, patients with any reversible defect, and patients with a fixed perfusion defect on MPS. In all, 156 subsequent patients underwent OLT. One or more reversible segmental perfusion defects on MPS were present in 14 patients (<3 segments, n = 12; 3 segments without obstructive coronary artery disease, n = 2). The risk of complications did not differ significantly between patients with normal MPS findings and patients with a reversible perfusion defect (odds ratio = 3.04, 95% confidence interval = 0.65-14.26, P = 0.16), although the study was not sufficiently powered to show a difference. The presence of 1 or more reversible defects on MPS was significantly associated with an increased incidence of all-cause 1-year mortality (hazard ratio = 3.17, 95% confidence interval = 1.02-9.83, P = 0.046). No significant difference in the outcomes of patients with normal MPS findings and patients with a fixed defect on MPS was found; the study was, however, not adequately powered to do so. In conclusion, the results of this small cohort study indicate that patients with mild to moderate reversible perfusion defects on MPS may have inferior survival characteristics in comparison with patients with normal MPS results. A prospective, adequately powered study is required to confirm the results of this study.

Tricuspid valve surgery in adults with a dysfunctional systemic right ventricle: repair or replace?

BACKGROUND

In patients with a right ventricle (RV) in the systemic position, tricuspid valve surgery for regurgitation beyond adolescence is a subject of debate. The aim of the present study was to evaluate the complications, survival, and benefit of tricuspid surgery in adult patients with an atrium-level correction for transposition of the great arteries or congenitally corrected transposition of the great arteries.

METHODS AND RESULTS

All adult patients (n=16; 7 men, 9 women; age 35+/-11 years) who underwent tricuspid valvuloplasty (n=8) or replacement (n=8) in the period 1999 to 2008 were included. Complications and survival were analyzed, and postoperative changes in RV function and functional class were evaluated. Tricuspid regurgitation was graded 1 to 4 according to its severity, RV dysfunction was graded as 1 to 4 (1=no dysfunction to 4=severe dysfunction), and functional status was determined according to New York Heart Association class. Although complications occurred in 11 patients, all could be managed adequately. Three patients died 109, 180, and 659 days after surgery, respectively, the first patient after tricuspid valve replacement and the latter 2 after tricuspid valvuloplasty. Overall, tricuspid valve function improved (from grade 3.1+/-0.8 to 0.9+/-1.0; P=0.001) and functional class improved (from 2.7+/-0.6 to 2.1+/-0.8; P=0.007), whereas RV function remained unchanged. After tricuspid valvuloplasty, however, recurrent moderate tricuspid valve regurgitation was observed frequently (n=3; 37%).

CONCLUSIONS

Mortality is rather low after tricuspid surgery in adult patients with mild to moderate RV dysfunction. In general, tricuspid valve function and functional class improve significantly after surgery, and systemic RV function is preserved. Tricuspid valvuloplasty, however, is associated with a high rate of recurrence of regurgitation.

Normal limits of the spatial QRS-T angle and ventricular gradient in 12-lead electrocardiograms of young adults: dependence on sex and heart rate

BACKGROUND AND PURPOSE

Normal limits of the spatial QRS-T angle and spatial ventricular gradient (SVG) are only available from Frank vectorcardiograms (VCGs) of male subjects. We determined normal limits for these variables derived from standard 12-lead electrocardiograms (ECGs) of 660 male and female students aged 18 to 29 years.

METHODS

A computer algorithm was used that constructed approximated VCG leads by inverse Dower matrix transformation of the 12-lead ECG and subsequently calculated the spatial QRS-T angle, SVG magnitude, and orientation.

RESULTS

In female subjects, the QRS-T angle was more acute (females, 66 degrees +/- 23 degrees; normal, 20 degrees-116 degrees; males, 80 degrees +/- 24 degrees; normal, 30 degrees-130 degrees; P < .001), and the SVG magnitude was smaller (females, 81 +/- 23 mV x ms; normal, 39-143 mV x ms; males, 110 +/- 29 mV x ms; normal, 59-187 mV x ms; P < .001) than in male subjects. The male SVG magnitude in our study was larger than that computed in Frank VCGs (79 +/- 28 mV.ms; P < .001).

CONCLUSIONS

The spatial QRS-T angle and SVG depend strongly on sex. Furthermore, normal limits of SVG derived from Frank VCGs differ markedly from those derived from VCGs synthesized from the standard ECG. As nowadays, VCGs are usually synthesized from the 12-lead ECG; normal limits derived from the standard ECG should preferably be used.