Dependence of the Ventricular Gradient
Beat-to-Beat Variability upon Severity of
Ischemic Heart Disease Syndromes

Liudas Gargasas, Alfonsas Vainoras, Svetlana Kaminskiene, Grazina Urbonaviciene,
Rimtautas Ruseckas, and Vytenis Miskinis

Institute of Cardiology, Kaunas University of Medicine, Kaunas, Lithuania

Correspondence: L Gargasas, Institute of Cardiology, Kaunas University of Medicine, Sukileliu av. 17-106, Kaunas, 3007 Lithuania.
E-mail: liugar@kmu.lt, phone +37037302881, fax +37037302872

1.  Introduction

The early detection of ischemic heart disease (IHD) is superior problem of cardiology, and searching for cost-effective noninvasive methods for diagnosis of IHD is the main task of scientific research in cardiology. In the last decade a beat-to-beat variation of various ECG parameters such as RR interval, late potentials, ventricular repolarisation and ventricular gradient have been investigated in aim to use these parameters for IHD detection [ Horinaka et al., 1995; Coudere et al., 1998; Sornmo et al., 1998; Murabayashi et al., 2002]. The investigation of ventricular gradient variability we started few years ago in aim to enrich the medical knowledge base of expert system for early detection of IHD that is developed in our institution [Gargasas et al., 1996]. The performed study permit to conclude that variability of ventricular gradient is good marker of IHD [Gargasas et al., 2000] and more precise investigation of this parameter must be performed. For this reason the aim of presented article was evaluation of beat-to-beat variation of ventricular gradient for patients with myocardial infarction, stable and unstable angina pectoris and with various degree of narrowing of coronary arteries.

2.  Materials and Methods

The subjects of this study were 44 healthy controls and 220 patients (pts) with IHD, which were distributed into seven groups: Group C - 44 healthy subjects, 28 females (F), 16 males (M), mean age 30±7 years. Group 1 - 63pts with by coronary arteriography excluded narrowing of coronary arteries(CA) : 17 – F, 46 – M; mean age 56±9 years; 28 with unstable angina pectoris(UAP), 27 with stable angina pectoris(SAP) and 8 with X syndrome. Group 2 – 57pts with by coronary arteriography confirmed narrowing (more than 50%) of one CA: 11 – F, 56 – M; mean age 61±9 years; 35 with UAP, 22 with SAP. Group 3 – 45pts with narrowing of three main CA: 11 – F, 34 – M; mean age 61±10 years; 30 with UAP, 16 with SAP. Group 4 – 55pts with MI: 12 – F, 43 – M; mean age 60±11 years; 29 with inferior MI, 23 with anterior MI and 3 with circumflex MI; 31 - MI with Q wave, 24 – MI without Q wave. Group 5 – 40pts from Group 2 and Group 3 with SAP. Group 6 – 62pts from Group 2 and Group 3 with UAP.

The 12 lead high resolution ECGs were recorded 5 minutes and analyzed by ECG computer analysis system and software for ventricular gradient calculation developed in our institution. Since in our cardiologic clinic the standard 12 lead ECG is used, Dower matrix for Frank VCG reconstructing have been used [Edenbrandt and Pahlm, 1988]. The magnitude of ventricular gradient (VGM), its standard deviation (SD), its coefficient of variation (CV) and SD of CV have been determined.

3.  Results and Discussion

The results of study are presented in Table 1. The CV was significantly (p<0.001) larger for patients with damaged CA (Groups 2-6) as compared with healthy subjects (Group C). The CV was also increased (5.6) but not significantly (p³0.1) in patients of Group 1 with slightly or not narrowed CA. The number of damaged CA had also influence to CV, and for patients with three narrowed CA (Group 3) was more prominent (7.1) as compared with cases, when only one CA (Group 2) was narrowed (6.4).

With respect to various IHD syndromes, the ventricular gradient was most variable for patients with MI (7.4), less – for patients with UAP (7.0) and SAP (6.1), but CV difference between UAP and SAP groups was not significant (p³0.1) as well as between MI and UAP groups.     

Table 1.    The values of the ventricular gradient magnitude(VGM) and its coefficient of beat-to-beat variation(CV)
for various IHD syndromes and degree of narrowing of coronary arteries.

The VGM was significantly (p<0.001) larger for healthy persons as compared with patients. There were also significant differences of VGM between other groups, but the value of VGM was not related to severity and syndromes of IHD.

4.  Conclusions

4.1. The coefficient of beat-to-beat variation of magnitude of ventricular gradient was significantly (p<0.001) larger for patients with clinically and arteriographically confirmed ischemic heart disease as compared with healthy persons. The ventricular gradient magnitude was significantly (p<0.001) higher in healthy persons as compared with patients.

4.2. The coefficient of variation of ventricular gradient magnitude was mediocre different in patients with narrowing of one and three coronary arteries – 5.6 and 6.4 respectively.

4.3. The coefficient of variation of ventricular gradient magnitude have tendency to increase with rise of severity of ischemic heart disease syndromes: for patients with stable angina pectoris it was 6.1, with unstable angina pectoris – 7.0 and with myocardial infarction – 7.4.

References

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