Biomedical subjects

Milla Karvonen

Publications and source records attributed to Milla Karvonen.

4 recordsLinked to original sources

PubMed2006

Magnetocardiographic assessment of healed myocardial infarction.

BACKGROUND: We evaluated the capability of multichannel magnetocardiography (MCG) to detect healed myocardial infarction (MI). METHODS: Multichannel MCG over frontal chest was recorded at rest in 21 patients with healed MI, detected by cine- and contrast-enhanced magnetic resonance imaging, and in 26 healthy controls. Of the 21 MI patients, 11 had non-Q wave and 10 Q wave MIs. QRS, ST-segment, T wave and ST-T wave integrals, ST-segment and T wave amplitudes, and QRS and ST-T wave magnetic field map orientations were measured. RESULTS: The MCG repolarization indexes, such as ST segment and ST-T wave integrals, separated the MI group from the controls (ST-T wave integral -1.4 +/- 5.3 vs 1.5 +/- 4.7 pTs, P = 0.034). The abnormalities were more distinct in the Q wave-MI than in the non-Q wave MI subgroup. In the latter, however, a trend similar to the Q wave MI group was found. The relation of QRS area to ST segment and T wave integral improved the detection of healed MIs compared to the ST-T wave indexes alone (QRS-ST-T discordance 14 +/- 10 vs 5.0 +/- 7.1 pTs, P = 0.003). When comparing the MI group to the controls, the orientation of the magnetic field maps differed in the ST-T wave maps (163 +/- 119 degrees vs 58 +/- 17 degrees, P < 0.001) but not in the QRS maps (111 +/- 95 degrees vs 106 +/-93 degrees, P = 0.646). CONCLUSIONS: The MCG repolarization variables can detect healed MI. These ST-T wave abnormalities are more pronounced in patients with Q wave MI than in patients with non-Q wave MIs. Relating the signals of depolarization and repolarization phases improves the detection of healed MI. Repolarization abnormalities are common in healed MI and thus should not always be interpreted as present ongoing ischemia.

Aged↗

PubMed2005

Spatial repolarization abnormalities in old myocardial infarction.

Conventional electrocardiogram criteria for myocardial infarction (MI) rely on QRS features, but ST-T segment is also affected. We recorded body surface potential mapping in 24 patients with prior MI and in 24 controls. T-wave maximum amplitude and QRS and ST-T integrals were automatically determined. Old MI was verified by magnetic resonance imaging. ST-T integral and T-wave maximum amplitude outperformed QRS integral in detecting MI, with area under receiver operating characteristic curve of 94%, 95%, and 83%, respectively. ST-T integral performed better in non-Q-wave than Q-wave MI, with area under receiver operating characteristic curve of 97% and 92%, respectively. QRS integral correlated negatively with ST-T integral in patients with MI (r = -0.58, P < .001) and positively in controls (r = 0.45, P < .001). In conclusion, ST-T integral proved equal to QRS integral in old MI detection. Inclusion of ventricular repolarization phase and development of electrocardiographic analysis over larger chest area may improve the QRS-based diagnosis of old myocardial infarction.

Adult↗

PubMed2004

Temporal analysis of the depolarization wave of healed myocardial infarction in body surface potential mapping.

BACKGROUND: We studied the ability of different time segments of the depolarization wave recorded with body surface potential mapping (BSPM) to detect and localize myocardial infarction (MI). METHODS: BSPM was recorded in 24 patients with remote MI and in 24 healthy controls. Cine and contrast-enhanced magnetic resonance imaging (MRI) was used as a reference method. Patients were grouped according to anatomical location of their MI. The QRS complex was divided into six temporally equal segments, for which time integrals were calculated. RESULTS: The time segments of the QRS complex showed different MI detection capability depending on MI location. For anterior infarction the second segment of the QRS complex was the best in MI detection and the optimal area was on the right inferior quadrant of the thorax (time integral average -1.5 +/- 1.8 mVms patients, 1.0 +/- 1.6 mVms controls, P = 0.002). For lateral infarction the first segment of the QRS complex performed best and the optimal area for MI detection was the left fourth intercostal area (time integral average 1.8 +/- 1.0 mVms patients, 0.7 +/- 0.5 mVms controls, P = 0.024). For inferior and posterior MI the mid-phases of the QRS complex were the best and the optimal area was the mid-inferior area of the thorax (time integral average -6.2 +/- 8.3 mVms patients, 3.3 +/- 4.3 mVms controls, P = 0.002; -9.1 +/- 6.1 mVms patients, 0.6 +/- 7.1 mVms controls, P = 0.001, respectively). CONCLUSIONS: Time segment analysis of the depolarization wave offers potential for improving the detection and localization of healed MI.

Aged↗

PubMed2002

Magnetocardiographic indices of left ventricular hypertrophy.

OBJECTIVE: We tested the hypothesis that multichannel magnetocardiographic (MCG) mapping can detect and quantify the degree of left ventricular hypertrophy (LVH). DESIGN: A cross-sectional study. SETTING: Helsinki University Central Hospital, a tertiary referral center. PARTICIPANTS: Forty-two patients with pressure overload induced LVH by gender-specific echocardiographic criteria (LVH group), and 12 healthy middle-aged controls. MAIN OUTCOME MEASURES: MCG QRS-T area integrals and QRS-T angle in magnetic field maps in relation to echocardiographic LVH as well as left ventricular (LV) mass and structure. Conventional 12-lead electrocardiographic (ECG) LVH indices (Sokolow-Lyon voltage, Cornell voltage, Cornell voltage duration product) were assessed for comparison. RESULTS: MCG QRS- and T-wave integrals provided complementary information of echocardiographic LV mass. Their combination, the QRS-T integral, and the QRS-T angle were increased in patients with LVH and, in those patients, correlated significantly with LV mass indexed to body surface area (r = 0.455;P = 0.002 and r= 0.379; P= 0.013, respectively). A QRS-T integral 16000 fT.s had identical sensitivity of 62% at 92% specificity as the gender-adjusted Cornell voltage duration product of 240 micro V.s for the detection of LVH. CONCLUSIONS: The MCG method can detect patients with LVH and also quantify the degree of LVH in patients with increased LV mass.

Aged↗