• Journal of Biomedical Engineering Research
• /
• v.23 no.1
• /
• pp.33-38
• /
• 2002

A Ventricular Assist Device(YAD) is used to support the injured natural heart So. when considering a control algorithm for YAD. it is important to reduce a natural heart's load to enhance its recovery condition. To reduce natural heart's load, a counterpulsation algorithm is used commonly. In this study, we developed a counterpulsation control algorithm for moving-actuator type VAD and tested its usefulness using in vitro MOCK circulatory system. To notice a natural heart's Pumping status, electrocardiogram(ECG) signal was used and as a result of test. the counterpulsation effect between YAD and a natural heart was occurred and Automatic Control Mode Transition was occurred properly.

• Journal of Biomedical Engineering Research
• /
• v.27 no.2
• /
• pp.78-82
• /
• 2006

The ventricular assist device(VAD) helps to reduce the overload against the patient's native heart(NH). The pulsatile VAD pumps out the ventricular blood to the aorta with pulsatile flow. If the VAD pulsates simultaneously with the NH, the ventricle of the NH could confronts abnormally elevated aortic pressure, and this could deteriorate the ventricle rather than assist to recover it. Thus counterpulsation algorithms to avoid copulsation have been adopted by many VADs, but these methods utilize electrocardiography or arterial pressure signals, which may have difficulties to acquire consistently for a long period. In this study, the copulsation estimation algorithm for the counterpulsation is developed using the VAD outlet pressure signal. The VAD outlet pressure signal is good to maintain for a long time and the sensor part could be integrated to the VAD as a built-in module. From the VAD outlet pressure signal and its pump rate information calculated with Fast Fourier Transform, pulse peaks by the VAD and the NH were extracted and the next copulsation time at which the VAD and the NH would pulsate simultaneously was estimated. This estimation algorithm was implemented by using PC MATLAB software and tested for various pump rate conditions with mock circulation system. For each condition, the copulsation time was estimated successfully. Consequently, the results showed the possibility to use the outlet cannula pressure signal in the copulsation estimation.

• Journal of Chest Surgery
• /
• v.28 no.9
• /
• pp.857-860
• /
• 1995

In a 53-year old male with post-infarction ventricular septal defect [VSD , owing to an acute exacerbation of pulmonary edema, respiratory failure developed, and the ventilatory support and intraaortic balloon counterpulsation [IABP were applied. At the following day, operation was performed with the aid of IABP. Under the cardioplumonary bypass, he underwent infarctectomy, trimming of VSD margin, patch closure of VSD and infarctectomy site. Left ventricular free wall rupture was detected during operation, which was confined with pericardial adhesion. Post-operative course was uneventful, and he could be discharged with minimal degree of dyspnea [NYHA class II .

• Journal of Chest Surgery
• /
• v.29 no.7
• /
• pp.689-699
• /
• 1996

An animal experiment was designed for the evaluation of in vivo performance of the newly developed electrohydraulic type ventricular assist device and its influence on the left ventricular function during pal- satile left ventricular assist. Eight adult sheep were incorporated into the study and data were collected from seven sheep. Total as- sist time ranged from 69 minutes to 7 days. The performance of the device was satisfactory both in asyn- chr nous and synchronous mode within the range of given native heart rate. More than 4 liters of device output could be reached within the range of normal left atral pressure without development of negative pressure in the left atrium. Moderate to severe degree of hemolysis was noted as evidenced by significant increase of plasma free hemoglobin level after 3 days of left ventricular support along with the presence of the small amount of thrombi around the floating disc type polymer valve apparatus reflecting that further study and refinement of the device need to be done in regard of biocompatibility and thromboresistance. The hemodynamics showed increase in heart rate (p < 0.05), cardiac output and left ventricular minute work (p < 0.05) after placement of the device at the flow rate of 2.0∼2.5 Llmin. The left atrial pressure, left ventricular pressure and LV dpldt were decreased after the device placement(p < 0.05). The endocardial viability ratio and oxygen contents of the mixed ven us blood and coronary venous blood were all increased (p < 0.05) after the device placement suggesting effective unloading of the left ventricle was accomplished. The myocardial perfusion was thought improved in synchronous counterpulsation as suggested by sig- nificant increase in endocardial viability ratio and coronary venous blood oxygen content in synchronous assist mode comparing with asynchronous mode.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1660-1664
• /
• 2008

Extra-corporeal Life Support System (ECLS) is the device used in emergency cases to substitute a extracorporeal circulation in open heart surgery, cardiac arrest or in acute cardiopulmonary failure. To obtain the effect of counter-pulsation on hemodynamic response in the ECLS quantitatively, we developed cardiovascular model which consists of 12 compartment model of heldt et al. and 3 compartment model of Schreiner et al. based on windkessel approximation. We compared coronary perfusion, arterial pulse pressure, cardiac output, and left ventricular pressure-volume diagram according to flow configuration such as counter-pulsation, copulsation, and continous flow. When counter-pulsation was applied, 5% higher coronary perfusion, 26% lower pulse pressure, and 2% higher cardiac output than copulsation condition were calculated. We conclude that counter-pulsation configuration in the ECLS is hemodynamically more stable than copulsation and influences the positive effect to recover ventricles.

• Journal of Chest Surgery
• /
• v.48 no.6
• /
• pp.381-386
• /
• 2015

Background: Postinfarction ventricular septal defects (pVSDs) are a serious complication of acute myocardial infarctions. The aim of this study was to analyze the clinical outcomes of the surgical treatment of pVSDs. Methods: The medical records of 23 patients who underwent operations (infarct exclusion in 21 patients and patch closure in two patients) to treat acute pVSDs from 2001 to 2011 were analyzed. Intra-aortic balloon counterpulsation was performed in 19 patients (82.6%), one of whom required extracorporeal membrane support due to cardiogenic shock. The mean follow-up duration was $26.2{\pm}18.6months$. Results: The in-hospital mortality rate was 4.3% (1/23). Residual shunts were found in seven patients and three patients required reoperation. One patient needed reoperation due to the transformation of an intracardiac hematoma into an abscess. No patients required reoperation due to recurrence of a ventricular septal defect during the follow-up period. The cumulative survival rate was 95.5% at one year, 82.0% at five years, and 65.6% at seven years. Conclusion: The use of a multiple-patch technique with sealants appears to be a reliable method of reducing early mortality and the risk of significant residual shunting in patients with pVSDs.

• Journal of Yeungnam Medical Science
• /
• v.17 no.1
• /
• pp.31-38
• /
• 2000

Background: We sought to examine the use and outcomes of early intraaortic balloon counterpulsation(IABP) combined with early reperfusion therapy in patients presenting cardiogenic shock complicated acute myocardial infarction. The usc of IABP in patients with cardiogenic shock is widely accepted. However there is not ample information on the use of this technique in patients with cardiogenic shock who arc treated with reperfusion therapy in Korea. Materials and Methods: Twenty-eight patients presented with cardiogenic shock were classified into two groups: the early IABP group (insertion within 12 hours after AMI onset time) and the late IABP group (insertion after 12 hours). We compared In-hospital mortality between the two groups (early IABP group vs late IABP group). Results: Two groups showed no significant difference in clinical feature and coronary angiographic results. Among total 28 patients, 7 patients were treated with thrombolytic therapy and 21 patients with PTCA. Insertion site bleeding, fever, thrombocytopenia were reported as some of the complications of IABP insertion. In-hospital mortalities in the early IABP group and late IABP group were 4 patients(25%) and 8 patients(66%), respectively(p<0.05). Early IABP insertion and early PTCA showed lower hospital mortality rates. There was significant difference in the time to PTCA after AMI onset between the two groups(p<0.05). Conclusion: IABP appears to be useful in patients presenting cardiogenic shock unresponsive medical therapy. Early IABP insertion and early reperfusion therapy may reduce in-hospital mortality rates of post-MI cardiogenic shock patients.

• Journal of Chest Surgery
• /
• v.34 no.12
• /
• pp.901-908
• /
• 2001

Background : Coronary artery bypass graft(CABG) in patients with advanced left ventricular dysfunction has often been regarded as having high mortality rate, despite the great improvement in operative result of CABG. With recent advances in surgical technique and myocardial protection, surgical revascularization improved the symptom and long-term survival of these high risk patients more than the medical conservative treatment. Material and Methold : Clinical data of 31(4.1％) patients with preoperative ejection fraction less than 30% among 864 CABGs performed between January 1995 and March 1999 were retrospectively analyzed and pre- and postoperative changes of the ejection fraction on echocardiography were analyzed. There were 26 men and 5 women. The mean age was 60.7 years(range 41 to 72 years). History of myocardial infarction(30 cases, 98％) was the most common preoperative risk factor. There were seven irreversible myocardial infarction on thallium scan. Most patients had triple vessel diseases(26 cases, 84％) and first degree of Rentrop classification(16 cases, 52％) on coronary angiography. The mean number of distal anastomosis during CABG was per patient was 4.9${\pm}$0.8 sites in each patient. In addition to long saphenous veins, the internal mammary artery was used in 20 patients. Total bypass time was 244.7${\pm}$3.7 minutes(range, 117 to 567 minutes), and mean aortic cross-clamp time was 77.9 ${\pm}$ 1.6 minutes(range, 30 to 178 minutes). There were five other reparative procedures such as two left ventricular aneurysrmectomy, two mitral repair, and one aortic valve replacement. There were twelve postoperative complications such as three cardiac arrhythmia, two bleeding(re-operation), one delayed sternal closure, eleven usage of intra-aortic balloon counterpulsation for low cardiac output. Two patients died, postoperative mortality was 6.5% . Twenty-nine patients were relieved of chest pain and left ventricular ejection fraction after operation was significantly higher(38.5${\pm}$11.6%, p 0.001) as compared with preoperative left ventricular ejection fraction(25.3${\pm}$2.3%). The follow up period of out patient was 25. 3 months. Conclusion: In patients with coronary artery disease and advanced left ventricular dysfunction, coronary artery bypass grafting can be performed relatively safely with improvement in left ventricular function, but it will be necessary to study long term results.