[Electrocardiogram readings in different degrees of secondary atrial septal defect]

AIM

To study the electrocardiographic characteristics of secondary atrial septal defect (ASD) depending on its size.

MATERIALS AND METHODS

A total of 80 patients (32 men and 48 women; mean age 23.5±2.7 years) with this defect were examined and divided into three groups according to its size relative to body surface area.

RESULTS

The degree of electrocardiographic changes in secondary ASD depended on its size: a significant positive correlation was established between defect size and P wave amplitude (r=0.8; p<0.005), as well as its duration (r=0.5; p<0.001). A positive correlation was noted between defect size and R wave amplitude in lead V1 (r=0.6; p<0.04), that and S wave amplitude in lead V5 (r=0.3; p<0.02); between the size of the defect and the degree of an increase in the total index RV1+SV5,V6 (r=0.7; p<0.02); and that and the degree of electrical heart axis (EHA) deviation to the right (r=0.3; p<0.03).

CONCLUSION

The degree of electrocardiographic changes in secondary ASD depends on its size. Giant defects are characterized by a frequent EHA deviation to the right, pronounced signs of right ventricular hypertrophy, and a higher prevalence of right bundle branch block.

[ECG changes after transcatheter correction of the secondary defect of the interatrial septum with Amplatzer occluder]

AIM

To study ECG changes after transcatheter correction of the interatrial defect (IAD) with Amplatter occluder.

MATERIAL AND METHODS

Secondary transcatheter IAD correction was made with Amplatzer Septal Occluder (AGA Medical Corporation, U.S.A.) in 33 adults (mean age 33.5 +/- 2.3 years) and 22 children (mean age 11.2 +/- 1.3 years). Short- and long-term outcomes of the defect correction were followed up for 1 to 12 months.

RESULTS

Ectopic atrial rhythm registered initially in 2 adult patients was corrected to 1 month after the operation. Normalization or reduction of the electric axis of the heart (EAH) deviation were achieved in 45.5% adults and 66.7% children who had vertical axis or right shift of the axis. Baseline right ventricular hypertrophy (RV, +SV(5,6) > 10.5 mm) was diagnosed in 10 adults and 9 children. To the end of the first year after IAD correction this hypertrophy was detected in 5 adults and 3 children (50 and 33.3%, respectively). Blockade of the right bundle of His (complete in 5 cases and incomplete in 23 cases) was diagnosed before treatment in 18 adults and 10 children. To month 12 after the defect correction incomplete blockade persisted only in 2 (11.1%) adults and 1 (10%) child. In 6 months P wave amplitude diminished in adults from 1.9 +/- 0.12 to 1.7 +/- 0.10 mm (p<0.01), in children--from 1.8 +/- 0.07 to 1.6 +/- 0.11 mm (p<0.05). QRS complex duration decreased both in adults and children (from 0.10 +/- 0.003 to 0.08 +/- 0.004 s, p<0.01 and from 0.09 +/- 0.003 to 0.08 +/- 0.002 s, p<0.05, respectively). In the latter duration of the interval P-Q reduced significantly in 3 months from 0.18 +/- 0.005 to 0.17 +/- 0.005 s (p<0.05).

CONCLUSION

ECG changes after transcatheter correction of IAD manifest with normalization of the EAH or reduction of its shift to the right, regress of right ventricular hypertrophy, elimination or reduction of the right bundle of His and absence of significant deterioration of cardiac arrhythmia.

[Cardiac function in secondary defect of interatrial septum and effects of its correction by Amplatzer occluder]

AIM

To study with impulse-wave Doppler and impulse-wave tissue Doppler investigation left and right ventricular (LV, RV) function in two age groups of patients suffering from an interatrial septum defect (ISD) before and two years after transcatheter correction.

MATERIAL AND METHODS

34 patients (20 females and 14 males) with secondary ISD aged 5 to 67 years were divided into two groups by age. Group 1 consisted of 11 patients aged under 16 years (mean age 10.4 +/- 0.9 years), group 2--of 23 patients over 16 (mean age 31.8 +/- 2.6 years). 30 controls were matched by age. LV and RV functions were assessed by Doppler index (DI) using impulse-wave Doppler and impulse-wave tissue Doppler investigation before the defect repair and 24 hours, 1, 3, 6, 12 and 24 months after it.

RESULTS

Indexed stretch-diameter of the defect in group 1 was 13.1 +/- 1.7 mm/m2, in group 2--11.7 +/- 0.8 mm/m2 (p > 0.05). Size of the occluder to body surface area was larger in group 1 patients (15.2 +/- 1.7 and 14.6 +/- 0.98 mm/m2, respectively; p > 0.05). There was initial LV and RV dysfunction in patients of both the groups. After transcatheter correction of ISD, RV DI normalized after 3 months after the defect correction in group 1, in group 2--only in 24 months. By linear RV function examination, after ISD correction DI reached control level in group 1 12 months, in group 2--24 months after surgery. LV DI in both groups did not differ from that of healthy controls 24 months after surgery. Lateral wall LV linear function examination after the defect correction discovered DI change after 1 month in group 1 (a 12% decrease; p < 0.01); control values were achieved only 2 years after surgery. In patients of group 2 DI reduced only 6 months after correction (by 14.5+ACUAOw- p +ADw- 0.01) and reached control values in 24 months. Tissue Doppler investigation of the mitral valve fibrous ring on the side of the interventricular septum after the occluder implantation showed that DI significantly decreased in group 1 in 1 month (by 9%). In group 2--in 6 months by 10% (p < 0.05). In 24 months DI achieved control values in both the groups.

CONCLUSION

Patients with ISD have LV and RV dysfunction. Recovery of LV and RV functional activity after transcatheter repair of the defect with Amplatzer occluder takes place later (for 12-24 months), in children recovery is faster than in adults.

[Remodeling of the heart after transcatheter repair of the secondary interatrial defect with amplatzer occluder]

AIM

To ascertain the effects of transcatheter repair of the secondary interatrial defect (IAD) with Amplatzer occluder on heart remodeling in respect to the patient's age.

MATERIAL AND METHODS

Transcatheter repair of the secondary IAD was made in 64 patients. Two groups were formed by the patients' age: group 1--age under 16 years (mean age 9 +/- 0.6 years) and group 2--age over 16 years (mean age 32 +/- 1.8 years). The control group consisted of 30 healthy subjects matched by age. Echocardiography measured size and volumes of the heart chambers, intracardiac hemodynamics before treatment of the defect and 24 hours, 1, 3, 6, 12 and 24 months after it.

RESULTS

The indexed diameter of the defect in group 1 was 16.5 +/- 1.6 mm/m2, in group 2--13.7 +/- 0.7 mm/m2 (p > 0.05). The size of the occluder, in relation to the surface area, was 20 +/- 1.5 and 16 +/- 0.8 mm/m2, respectively (p < 0.05). 24 hours after the defect repair the right ventricle volume reduced by 29% in group 1 and by 21%--in group 2. The right atrium volume reduced significantly also. Mean pulmonary arterial pressure (PAP) in both groups diminished from 22 +/- 0.7 to 19 +/- 0.7 mmHg and from 24 +/- 1.0 to 20 +/- 0,8 mmHg, respectively. The left atrium decreased by 34 and 32%, respectively (p < 0.001). Remodeling reduced RV-LV in both groups by 22 and 23% (p < 0.001), respectively. 3 months after the defect repair all the indices reached control values. 12 months after the correction hemodynamics in the patients was the same with the healthy examinees. The time and degree of reduction of the right heart were similar in the groups, the volumes diminished by about 50%. 12 months after the repair in 4 of 18 patients of group 2 (22%) the right atrium and ventricle were larger than in healthy subjects though less than before the repair.

CONCLUSION

Transcatheter repair of the secondary IAD with Amplatzer catheter leads to early noticeable reduction of the right heart. The type of the changes is similar in both age groups and does not depend on the size of the implanted occluder. Not all the patients over 16 years of age achieve normal sizes of the RV and RA 12 months after the defect correction.

Prevalence of cardiac beta-myosin heavy chain gene mutations in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a frequent, autosomal-dominant cardiac disease and manifests predominantly as left ventricular hypertrophy. Mutations in the cardiac beta-myosin heavy chain gene (MYH7) are responsible for the disease in about 30% of cases where mutations were identified. We clinically evaluated a large group of 147 consecutive HCM patients from three cardiology centers in Germany, Poland, and Kyrgyzstan according to the same protocol. The DNA of the patients was systematically analyzed in the whole coding region of the MYH7 gene using PCR, single-strand conformation polymorphism analysis, and automated sequencing. Eleven different missense mutations (including seven novel ones) in 11 unrelated patients were identified, showing a mutation frequency of 7.5% in the study population. We further examined the families of five patients (three of German, one of Polish, and one of Kyrgyz origin) with 32 individuals in total. We observed a clear, age-dependent penetrance with onset of disease symptoms in the fourth decade of life. Genotype-phenotype correlations were different for each mutation, whereas the majority was associated with an intermediate/malign phenotype. In conclusion, we report a systematic molecular screening of the complete MYH7 gene in a large group of consecutive HCM patients, leading to a genetic diagnosis in 38 individuals. Information about the genotype in an individual from one family could be very useful for the clinician, especially when dealing with healthy relatives in doubt of their risk about developing HCM. The increasing application of genetic screening and the increasing knowledge about genotype-phenotype correlations will hopefully lead to an improved clinical management of HCM patients.

Effects of Intermittent Exposure to High Altitude on Pulmonary Hemodynamics: A Prospective Study

Chronic alveolar hypoxia due to disease or low atmospheric pressure at high altitude results in the development of hypoxic pulmonary hypertension. The effects of intermittent hypoxia on pulmonary hemodynamics in healthy men have not been studied. We aimed to investigate, prospectively, pulmonary hemodynamics in workers commuting between an elevation of 3700 and 4200 m (4-week working shift) and lowland, below 500 m (4 weeks of holiday). Pulmonary hemodynamics has been investigated by Doppler echocardiography in 26 healthy Caucasian males, mean age 42 +/- 9 yr. First at lowland (760 m) and next during the fourth week of work at high altitude. Investigations were repeated in 21 subjects 1 year later at the end of the high-altitude exposure. The third series of investigations was performed 2 yr after the initial ones in 10 subjects who earlier had shown the strongest hypoxic vasoconstriction. At lowland, subjects presented with normal pulmonary hemodynamics. At high altitude, mean pulmonary artery pressure (PAPm) rose from 14.7 +/- 2.7 mmHg to 25.8 +/- 8.3 mmHg. One year later the PAPm remained unchanged in hypoxic conditions (25.0 +/- 7.3 mmHg). At the end of a 2-year follow-up of 10 "hyperreactors," PAPm measured at the end of the hypoxic exposure was the same as at the initial investigation, averaging 28 +/- 4.0, 28 +/- 3.5, and 29 +/- 2.5 mmHg at the beginning and at 1 and after 2 yr of intermittent exposure to high altitude. We concluded that intermittent exposure to 4000 m lasting 3 yr does not lead to development of permanent pulmonary hypertension.

[Three week stay at a height of 3700-4200 m. causes mild pulmonary hypertension in healthy men]

High altitude hypoxia leads to development of hypoxic pulmonary hypertension. We studied 27 healthy caucasian subjects aged 24 to 59 years, mean 41.6 +/- 9 y, working on 4 week shifts at the Kumtor gold mines at the altitude of 3700-4200 m. Pulmonary circulation was studied twice by Echo-Doppler using Toshiba SSD-160. The first investigation was performed at the level of 730 m at the end of 4 week holiday spent in the lowland, the second investigation on the 23rd day at altitude. Pulmonary artery acceleration time decreased from 131 +/- 14 ms to 105 +/- 14 ms (p < 0.001). Calculated pulmonary arterial mean pressure increased from 15.1 +/- 2 to 25.4 +/- 8 mmHg (p < 0.001). Right ventricular preejection period increased from 93 +/- 14 to 102 +/- 19 ms (p < 0.05). Other echo variable did not change. We conclude that healthy subjects submitted to 3 week exposure to high altitude hypoxia (oxygen pressure in the inspired air 82-88 mmHg), developed mild pulmonary hypertension, regressing after recovery at the lowland.

[Quality of sleep and periodic breathing in healthy individuals working at an altitude of 3700 meters]

We performed full polysomnography (PSG) in 7 healthy miners of Kyrghyz origin (mean age 25 +/- 6 years) working in 2 weeks shifts at Kumtor gold mines at the elevation of 4200 m. They slept in comfortable dormitories situated at 3700 m. To avoid acute mountain sickness all subjects received acetazolamide 3 x 0.25 daily during 2 days preceding ascent and during 2 days at altitude: PSG was performed three times: at 760 m (1) and on the 1st (2) and 7th night (3) after rapid ascent (aircraft) to high altitude using SomnoTrac 4250 sleep laboratory. We found that sleep efficiency was good at lowland and in the mountains averaging 81.79% and 84% respectively. Although there were no significant differences in percentage of sleep stages and of total sleep time between lowland and both nights at high altitude, arousals and awakenings were more frequent in the mountains. Episodes of periodic breathing (PB) appeared at high altitude. There was a large individual variability in PB on both nights at altitude. The time spent in PB ranged from 4 to 30 minutes during the first night at altitude and from 3 to 17 minutes during the second one. PB appeared mainly during non-REM sleep and aggravated arterial blood desaturation.