Ying-Fu Chen

Uneven myocardial hypothermia among cardiac chambers during hypothermic myocardial preservation.

During the development of methods to protect the heart from ischaemic injury, attention has been focused on protection of the left ventricle. In an attempt to assess right heart preservation. 55 consecutive patients undergoing open heart surgery were studied. Mean aortic cross-clamp time was 59.3 +/- 29.4 min. Temperature probes were inserted into the right atrium (RA), right ventricle (RV), and left ventricle (LV). During cardioplegia, the mean myocardial temperatures of RA, RV and LV were 19.1 degrees +/- 4.1 degrees C, 12.7 degrees +/- 4.8 degrees C and 7.3 degrees +/- 3.4 degrees C, respectively. Of the LV temperature measurements, 67.2% were 10 degrees C or lower. By contrast, 94.1% of RA measurements and 58.5% of RV measurements were above 10 degrees C. The inhomogeneity of chamber temperatures was observed irrespective of the patients disease or age and whether the atrium or right ventricle were open or not. Hearts with mitral regurgitation (MR), in contrast to mitral stenosis and stenoinsufficiency, had higher LV temperatures, similar to those in the RV. We conclude that there is uneven hypothermia among the three cardiac chambers during hypothermic cardioplegic arrest, regardless of disease states except MR and regardless of age and procedure performed.

Comparison of Blood Cardioplegia to Electrolyte Cardioplegia on the Effectiveness of Preservation of Right Atrial Myocardium: Mitochondrial Morphometric Study

The right atrium differs from the left ventricle in two respects during cardioplegic arrest: a higher proportion of noncoronary collateral flow is delivered to the right atrium, and the atrium is frequently excluded from topical ice cooling because of its higher position relative to the left ventricle. These factors result in early rewarming of atrial myocardium. To the best of our knowledge, the surgical literature contains no reports on whether blood cardioplegia can provide better atrial myocardial preservation than electrolyte cardioplegia. Twenty consecutive patients who underwent cardiac operations were randomly selected to receive blood cardioplegia (Group 1) or electrolyte cardioplegia (Group 2). Hypothermia was achieved by systemic cooling and continuous topical cooling with ice slush. Stereological morphometric study of mitochondria was performed on 40 biopsy specimens taken from the right atrium prior to aortic cross-clamping (preischemia) and at the end of ischemia. In Group 1, total aortic cross-clamp time was 72.8 +/- 32.5 minutes. The mean mitochondrial surface area before ischemia was 0.224 +/- 0.032 mu 2 and after ischemia, 0.336 +/- 0.032 mu 2, a 50.0% increase in mitochondrial size. In Group 2, total aortic cross-clamp time was 69.7 +/- 30.9 minutes. The mean mitochondrial surface area before ischemia was 0.205 +/- 0.025 mu 2 and after ischemia, 0.439 +/- 0.111 mu 2, an average increase in mitochondrial size of 114.2%. There was no significant difference between the two groups in mitochondrial size before ischemia. However, after ischemia the mean mitochondrial surface areas were significantly different (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the effectiveness of myocardial preservation in right atrium and left ventricle.

Ten patients underwent cardiac operations during which myocardial preservation was provided by systemic hypothermia, topical cardiac cooling, and cold blood cardioplegia. The duration of ischemia ranged from 45 to 142 minutes (mean, 84.2 +/- 36.2 minutes). Two serial specimens (preischemic and ischemic) were obtained from the right atrium and the left ventricle, respectively; thus, a total of 40 biopsy specimens was obtained from these 10 patients. A combination of grading of ischemic injury and stereological morphometric measurement of mitochondria was performed to assess the effectiveness of myocardial preservation. Our findings from the mitochondrial score studies (grading of ischemic injury) were as follows. In the right atrium, the average mitochondrial score rose from 0.337 +/- 0.235 in the preischemic stage to 1.969 +/- 0.492 in the ischemic stage. In contrast, the average mitochondrial score for the left ventricle was only elevated from 0.380 +/- 0.161 to 1.353 +/- 0.396. The difference between preischemia of the right atrium and left ventricle is not statistically significant, but the difference between ischemia of these chambers is significant (p less than 0.01). Our stereological morphometric studies revealed that in the left ventricle, the average mitochondrial surface area was 0.316 +/- 0.046 micron 2 in the preischemic stage and 0.347 +/- 0.073 micron 2 in the ischemic stage, a 9.8% increase in mitochondrial size (not significant). In contrast, the mitochondrial surface area of the right atrium showed a mean increase of 65.8%, from 0.231 +/- 0.038 micron 2 in the preischemic stage to 0.383 +/- 0.057 micron 2 in the ischemic stage (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

The Superiority of Blood Ober Electrolyte Cardioplegia in Prevention of Supraventricular Arrhythmias and Conduction Disturbances Following Open Heart Surgery

A total of 111 patients underwent open heart surgery during which myocardial preservation was provided by systemic hypothermia, topical cardiac cooling and cardioplegic solution (blood cardioplegia or electrolyte cardioplegia). The purpose of this study was to determine if the use of the different types of cardioplegia correlated with the occurrence of postoperative supraventricular arrhythmias and conduction disturbances. These partients were retrospectively divided into two groups according to the difference in the infused cardioplegic solutions. The group receiving blood cardioplegia (BCP) comprised 69 patients and the group receiving electrolyte cardioplegia (ECP) had 42 patients. There were a longer ischemic time and bypass time in the BCP group as compared with those of the ECP group (68.4±36.1 minutes v.s. 50.7±37.0 minutes, p＜0.01;93.7±48.9 minutes v.s. 65.5±39.1 minutes, p＜0.005). However, the result shows a significantly lower incidence of supraventricular arrhythmias and conduction disturbances in the BCP group (5.8%) as compared with the ECP group (21.4%; p=0.013). There was no significant difference in incidence of supraventricular arrhythmias and conduction disturbances between the two groups when the ischemic time was less than 60minutes (6.7% v.s. 17.2%, p＞0.05). On the other hand, there was a significant difference between the two groups when the ischemic time was longer than 60minutes (5.1% v.s. 30.8%, p=0.01). Furthermore, the presence or absence of preoperative electrocardiographic right atrial hypertrophy or enlargement had no significant effect on the occurrence of postoperative supraventricular arrhythmias and conduction disturbances (14.3%v.s. 11.3%, p＞0.05). It is concluded that (1) blood cardioplegic solution can afford better protection for preventing postoperative supraventricular arrhythmias and conduction disturbances. (2) No correlation was observed between preoperative electrocardiographic right atrial hypertrophy or enlargement and the incidence of postoperative supraventricular arrhythmias and conduction disturbances.

Open Heart Surgery in a Patient with an Implanted Pacemaker: Case Report

When a patient has a pacemaker and requires operation, surgeons have to consider some possible intraoperative pacemaker complications induced by electrocautery. Electrocautery is commonly used during surgery to achieve hemostasis. However, this very effective tool may introduce innumerable problems in the paced patient, including irreversible damage to the pulse generator, pacemaker reprogramming, induction of a rise in the capture threshold, and ventricular fibrillation. Although electrocautery may be avoided in some surgical procedures, open heart surgery cannot be performed without it. One case is presented to illustrate how to achieve hemostasis while decreasing electric interference and how to protect the permanent pacemaker while avoiding those possible complications during the defibrillation. The purpose of this article is to call attention to potential problems induced by electrocautery and in an effect to facilitate the perioperative management of the paced patient undergoing open heart surgery.

Successful Surgical Correction of Acute Ascending Aortic Dissection: A Case Report

The prognosis of patients with acute aortic dissection is extremely poor, especially when involving the ascending aorta. It has long been recognized as a catastrophic cardiovascular event. Acute dissections involving an ascending aorta have approximately a 90 percent acute mortality rate if left untreated or treated medically. Therefore, nearly all patients with acute ascending aortic dissection should be surgically treated immediately after a diagnosis has been established. A 60-year-old man having an acute ascending aortic dissection was successfully operated on with a resection of the dissecting aorta which was replaced with a Dacron graft. The postoperative course was complicated with a respiratory insufficiency and a disruption of the sternal wound. A 4 years follow-up confirmed the patient was in good condition. This is the first successfully operated case of acute ascending aortic dissection at our hospital.

A simple and rapid method for obliteration of patent ductus arteriosus in the small infant.

There was a 45-day old small baby with 2,650 g of body weight undergoing surgical operation of patent ductus arteriosus because of congestive heart failure and severe pulmonary hypertension. A simple and rapid method as proposed by Traugott et al for obliteration the ductus with two ligaclips (Ethicon LC300) is presented.