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Biomedical subjects

N T Kouchoukos

Publications and source records attributed to N T Kouchoukos.

At least 181 records · Page 10Linked to original sources
PubMed1977

Sequence of retrograde atrial activation of the human heart. Correlation with P wave polarity.

Studies were performed in 6 patients during open heart surgery to correlate the relative sequence of atrial activation with the polarity of the retrograde P wave in electrocardiographic leads II, III, and aVF. Bipolar atrial electrograms were recorded from selected sites during threshold pacing from sites low on the right side of the atrial septum which when paced resulted in the inscription of either negative or positive P waves in electrocardiograph leads II, III, and aVF. When the atria were paced from a site just anterior to the coronary sinus ostium (negative P waves), the posteroinferior left atrium was activated early and Bachmann's bundle late during the inscription of the P wave. When the atria were paced from a site 2 cm anterior to the coronary sinus ostial site (positive P waves), Bachmann's bundle was activated early during the P wave and the posteroinferior left atrium was activated relatively later. These data from man are consistent with previous studies in the canine heart. Therefore, we deduced that in man during the inscription of negative retrograde P waves in leads II, III, and aVF, atrial activation occurs primarily in a retrograde fashion. However, during the inscription of positive retrograde P waves in man, activation occurs rapidly up the interatrial septum (we believe via the anterior internodal pathway) to Bachmann's bundle, from where it then spreads in a manner similar to that which occurs during normal sinus rhythm.

Adolescent↗
PubMed1977

Entrainment and interruption of atrial flutter with atrial pacing: studies in man following open heart surgery.

To examine the question of why the pacing rate and duration of atrial pacing are crucial factors in the successful interruption of atrial flutter, studies were performed on 30 patients in the period following open heart surgery. In each patient the diagnosis of atrial flutter was made using a pair of wire electrodes placed on the right atrial epicardium at the time of operation and brought out through the anterior chest wall. The same electrodes were used for atrial pacing. Pacing faster than the spontaneous rate of the atrial flutter which failed to interrupt the atrial flutter was associated with transient entrainment of the atrial flutter up to the atrial pacing rate. Atrial flutter was interrupted successfully when the atria were paced at a rate which was too fast for the atrial flutter to follow. This was heralded by the conversion of previously negative flutter waves to positive atrial complexes in ECG lead II. When pacing the atria at a constant rate, 2-22 seconds with a mean of 10 seconds were required to interrupt the atrial flutter.

Adult↗
PubMed1977

Long-term results of the medical treatment of coronary artery disease.

The natural history of patients with ischemic heart disease varies widely depending upon the anatomic lesion and extent of left ventricular dysfunction. Several clinical variables may also be used to help determine the likelihood of long-term survival. Individuals with high-grade isolated disease of the left anterior descending coronary artery, without significant impairment of ventricular function, have little morbidity and mortality for the 2-year period after arteriography. At the other end of the spectrum, medically treated patients with stenosis of the left main coronary artery or three-vessel disease without such involvement have a reduced life expectancy compared with patients treated surgically. Global judgments on long-term results of the medical treatment of coronary artery disease are meaningless. Efforts should be made to delineate optimal treatment for various subgroups of patients under the broad rubric of ischemic heart disease.

Adult↗
PubMed1977

Late results with synthetic valved external conduits from venous ventricle to pulmonary arteries.

Eighty-five patients operated on before January 1976 have survived at least 30 days after insertion of a valved external conduit by the venous ventricle (usually the right) and the pulmonary arteries as a part of the repair of their congenital heart disease. Follow-up information is available on 83 patients, and mean follow-up time has been 27.7 months. Seven patients have required reoperation because of obstructive complications. Actuarial analysis indicates that the proportion of patients requiring reoperation is 4.0 +/- 2.8% at 2 years, 12.9 +/- 5.5% at 3 1/2 years, and 30.4 +/- 12.1% at 5 years. In five patients compression of the conduit between the sternum and heart was the primary cause of the obstruction. The proportion requiring reoperation for conduit compression is 2.0 +/- 2.0% at 2 years, 8.6 +/- 4.9% at 3 1/2 years, and 27 +/- 12.4% at 5 years. Age at operation is not related to the proportion of patients requiring reoperation, nor is the type of conduit. No patients have yet required reoperation for conduit compression whose operation has been done since we began systematically to position the conduit well away from the sternum. By actuarial analysis the proportion of patients surviving 5 years is 76.7%. Of those alive at follow-up examination, 78% were without limitation of activity.

Adolescent↗
PubMed1976

Surgical versus medical treatment in disease of the left main coronary artery.

Data from 179 patients with a significant lesion of the left main coronary artery were reviewed to compare survival with and without bypass graft surgery. 149 patients were treated with bypass grafting. Of 38 patients treated medically, 24 were suitable for surgery but either had been evaluated before the widespread use of bypass grafting procedures or preferred medical treatment. Major prognostic factors in this group were comparable to the surgical patients. The survival-rate was consistently higher for the surgically treated group and differed significantly (P less than 0-02) for the total duration of follow-up. At twelve months, 89% of the surgical group were alive, but only 73% of the comparable medical group; at twenty-four months, survival-rates were 86% and 65% respectively. These findings, corroborated by other data, suggest that surgery prolongs life for these patients.

Aged↗
PubMed1976

Early risks of open heart surgery for mitral valve disease.

During 1972 and 1973, a total of 235 patients had open heart surgery for mitral valve disease unassociated with significant aortic or rheumatic tricuspid valve disease. Thirty-one underwent closed heart mitral commissurotomy, without mortality. Of the 204 patients undergoing open operation, 125 had sequential measurement of cardiac output and mixed venous oxygen pressure. The hospital mortality rate was 6.4 percent in the larger group of 204 patients and in the 125 with cardiac output measurements. The rate was greater in those with class IV disability (New York Heart Association criteria) preoperatively than in those with class III or II disability. The mean +/- standard deviation of the average cardiac index early postoperatively was 2.05 +/- 0.579 liters-min--1-m--2. Cardiac index was lower in the patients who died early postoperatively than in those who did not. The probability of hospital death was a significant function of cardiac index. The predicted probability of death was 10 percent with an average cardiac index of 1.42 liters-min--1-m--2 and increased sharply with lower indexes. Cardiac index was lower early postoperatively than preoperatively, and was lower in patients in class IV than in those in class III. There was no significant difference in cardiac index between patients with mitral valve replacement and those in repair. A history of closed commissurotomy, age, duration of cardiopulmonary bypass, duration of cardiac ischemia and method of myocardial preservation did not significantly influence cardiac index or hospital mortality rate. There was no significant relation between mixed venous oxygen pressure and hospital death. Further improvement in results of mitral valve surgery requires adequate preservation of left ventricular performance before, during and after operation.

Adolescent↗
PubMed1976

Indications for and resluts of tricuspid valve replacement.

A review of our experience with tricuspid valve replacement over a 7.5-year period is presented. Isolated disease of the tricuspid valve was encountered infrequently [8 of 87 patients] and was due to a variety of causes. In the remaining cases, the tricuspid disease was associated with rheumatic valvular disease of the mitral and/or aortic valves. The hospital mortality for the entire group of patients was 22%, and the late mortality during a mean follow-up of 32 months was 16%. Operative and late mortality were clearly affected by the severity of myocardial dysfunction present preoperativley. Problems related to the prosthetic valves and to anticoagulant therapy were relatively few. Our present indications for replacement of the tricuspid valve and presented. Earlier operative intervention in patients with tricuspid valvular disease should improve the early and long-term results.

Adolescent↗
PubMed1976

Debate on valvular heart disease. Con: early surgical intervention in valvular heart disease.

Patients with valvular heart disease, particularly aortic and mitral incompetence, may have significant derangement of myocardial function, often in the absence of significant symptoms, which directly affects early and late survival and functional status following valve replacement. With declining hospital mortiality rates and improved valvular prostheses, consideration must be given to valve replacement in patients of this type in order to preserve myocardial function. This should improve long-term survival and the functional results following valve replacement. Attention should be directed to identifying and closely observing patients of this type, perhaps with noninvasive techniques, and proceeding with valve replacement before irreversible myocardial damage has occured.

Aortic Valve Insufficiency↗
PubMed1976

Continuous rapid atrial pacing to control recurrent or sustained supraventricular tachycardias following open heart surgery.

A technique is described to control recurrent or sustained supraventricular tachycardia associated with rapid ventricular rates following open heart surgery. The technique utilizes a pair of temporarily implanted atrial epicardial wire electrodes to pace the heart. In one group of patients with recurrent atrial flutter and 2:1 A-V conduction, continuous rapid atrial pacing at 450 beats/min produced and sustained atrial fibrillation. The ventricular response rate immediately slowed when compared to that during atrial flutter, and if further slowing was required, it was easily accomplished by the administration of digitalis. Another group of patients with different arrhythmias (recurrent paroxysmal atrial tachycardia, sustained ectopic atrial tachycardia, or sinus rhythm with premature atrial beats which precipitated runs of atrial fibrillation) was treated with continuous rapid atrial pacing to produce 2:1 A-V block. In all instances, the continuous rapid atrial pacing suppressed the supraventricular tachycardia and maintained the ventricular response rate in a therapeutically desirable range. It was demonstrated that the technique is safe, effective, and reliable.

Adult↗
PubMed1975

Surgical versus medical treatment of occlusive disease confined to the left anterior descending coronary artery.

The results of saphenous vein bypass grafting and medical treatment were compared in 53 patients with stable angina pectoris, high grade occlusive disease confined to the left anterior descending coronary artery and normal or minimally impaired left ventricular function. Survival, incidence of myocardial infarction, relief of angina and response to exercise testing were evaluated. In the 29 surgically treated patients, followed up a mean of 24 months, there were two late deaths (7 percent) and five myocardial infarctions (17 percent). Twelve patients (41 percent) were free of angina and the majority had increased exercise performance when tested up to 18 months postoperatively. In the 24 medically treated patients, there were no deaths and one myocardial infarction (4 percent) in a mean follow-up period of 37 months. Six patients (25 percent) were free of angina. Less improvement in exercise performance was observed than in the surgically treated group. This subset of patients with isolated left anterior descending coronary artery disease has a favorable prognosis that is not enhanced by bypass grafting. Surgical treatment is more effective than medical treatment in relieving angina and improving exercise performance in the early years after coronary arteriography.

Angina Pectoris↗
PubMed1975

Late stenosis of Starr-Edwards cloth-covered prostheses.

During a two-year period (August, 1971, to July, 1973) 1 Starr-Edwards Model 2400 and 135 Starr-Edwards Model 2320 aortic prostheses were inserted without postoperative antiocagulant therapy. Seven of these valves (including the Model 2400 prosthesis) have been replaced because of substantial transvalvular gradients resulting from fibrous overgrowth of the valve orifice. Symptoms associated with aortic stenosis occurred an average of nine months after the initial operation. Six patients had severe anemia (packed cell volume less than 30%) and hemolysis (serum lactic dehydrogenase greater than 900 units). Gradients across the prostheses ranged from 66 to 105 mm Hg with a mean of 87 mm Hg. One valve was size 8A, 3 were 10A, and 1 was 12A. Fibrous ingrowth was not observed in an earlier group of 23 patients receiving the Model 2310 or Model 2320 prosthesis who were placed on long-term anticoagulant therapy. These findings, coupled with a 9% incidence of thromboembolism at one year, indicate that patients having these prostheses inserted should receive long-term anticoagulant therapy.

Adult↗
PubMed1975

P waves during ectopic atrial rhythms in man: a study utilizing atrial pacing with fixed electrodes.

Threshold bipolar pacing was performed from one of 12 selected atrial sites with temporary implanted electrodes in 69 patients following open-heart surgery in order to study P wave polarity and morphology and the P-R interval during paced ectopic atrial rhythms. A negative P wave was recorded in lead I only with pacing the left atrium and only when pacing near the left pulmonary veins. A positive bifid P wave in V1 was recorded only with left atrial pacing and only when pacing was near the inferior pulmonary veins and coronary sinus. P wave polarity and morphology were otherwise of no use in localization of the origin of the impulse in these studies. The pacing stimulus to P wave interval was found to vary between 10 and 54 msec, making the duration of the P-R interval an unreliable indicator of the site of origin of the paced impulse. Although the relation of these paced rhythms to spontaneously occurring ectopic rhythms is unclear, the previously published criteria for localizing ectopic atrial rhythms are again demonstrated to be unreliable. P wave polarity and morphology and the P-R interval are of limited value in ascertaining the origin of ectopic atrial rhythms in man.

Adult↗
PubMed1975

Valve replacement and myocardial revascularization. Results of combined operation in 59 patients.

Fifty-nine patients (mean age 57 years) underwent aortic valve replacement or mitral valve replacement combined with saphenous vein bypass grafting (39 single, 19 double, 1 triple) between May, 1970 and January, 1974. The hospital mortality for aortic valve replacement was 4.7% (2 of 43 patients) and for mitral valve replacement 6.3% (1 of 16 patients). There was a 21% incidence of postoperative myocardial injury in the patients with aortic valve replacement and a 6.2% incidence in the patients with mitral valve replacement. Variations in operative technique and in the methods of intraoperative myocardial preservation (coronary perfusion or profound hypothermic ischemic arrest) did not affect hospital mortality or the incidence of myocardial injury. Prolonged periods of ischemic arrest (greater than 50 minutes) were not used. The late mortality for aortic valve replacement was 16.3% (seven patients) and for mitral valve replacement 25% (four patients). There was symptomatic improvement in the majority of survivors. Operative mortality rates for the combined procedures are comparable to those from our institution for valve replacement alone.

Adult↗