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Biomedical subjects

L Watkins

Publications and source records attributed to L Watkins.

At least 73 records · Page 4Linked to original sources
PubMed1984

Operative intervention for postinfarction angina.

Thirty-four patients (26 men and 8 women) underwent myocardial revascularization following myocardial infarction (MI) at the Johns Hopkins Hospital during 1980 through 1982. Average age was 59 years. Of the 33 patients with unstable angina, 61% had ischemia in the infarct zone and 39% had "ischemia at a distance." Mean time from MI to operation was 16 days. The MIs were equally divided between a transmural and a subendocardial location. Eleven patients had a history of congestive heart failure. Intraaortic balloon pumping was used preoperatively for anginal stabilization in 14 patients. Mean ejection fraction for the group was 52%. There were 3 operative deaths, all 3 due to myocardial failure. Late follow-up (mean, 13.7 months; range, 6 to 35 months) is complete for 28 patients. There was 1 late death, secondary to cardiac failure. There were no late MIs. Angina had recurred in 5 patients, but only 2 were taking antianginal medication. At the time of follow-up, 52% of patients were in New York Heart Association Functional Class I. This experience suggests that operative intervention for postinfarction angina can be accomplished with an acceptable mortality and thereby increase survival, reduce the later occurrence of MI, and relieve angina in this high-risk group.

Aged↗
PubMed1984

The automatic implantable cardioverter-defibrillator.

The automatic implantable cardioverter-defibrillator is an electronic device designed to monitor the heart continuously, to identify malignant ventricular tachyarrhythmias, and then to deliver effective countershock to restore normal rhythm. There are two defibrillating electrodes which are also used for waveform analysis; one is located in the superior vena cava, the other is placed over the cardiac apex. A third bipolar right ventricular electrode serves for rate counting and R-wave synchronization. When ventricular fibrillation occurs, a 25 joule pulse is delivered; when ventricular tachycardia faster than a preset rate is detected, the discharge is R-wave synchronized. The device can recycle three times if required. Special batteries can deliver over 100 shocks or provide a 3-year monitoring life. Implantation of the device is made either through a thoracotomy or by a subxiphoid approach. Thus far, the device has been implanted in 160 patients with a follow-up of 42 months. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation occurred only rarely and is dealt with most successfully through recycling. Actuarial analysis of the initial 52 patients has indicated 22.9% one-year total mortality, a 52% decrease from the 48% mortality that would be expected in the same group of patients without the device; the mortality attributed to arrhythmias was only 8.5%. In conclusion, the automatic cardioverter-defibrillator can reliably identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in survival in properly selected high-risk patients.

Death, Sudden↗
PubMed1984

Automatic implantable cardioverter-defibrillator structural characteristics.

There are a number of equipment options and surgical techniques available for automatic implantable cardioverter-defibrillator implantation. The system can be successfully used even in problem cases where restrictions may be imposed because of physical build or the presence of other implanted devices. The sensing requirements and energy output of the units can be tailored to the exact needs of the particular patient. Battery life and device function are easily monitored periodically following implantation, making possible elective replacement of the pulse generator when the batteries become depleted.

Arrhythmias, Cardiac↗
PubMed1984

Implantable cardioverter-defibrillator: patient selection and implantation protocol.

The experience obtained from the clinical trials with the automatic implantable cardioverter-defibrillator have reemphasized the need for a detailed pathophysiologic evaluation of the patient preoperatively. This evaluation requires careful documentation of the probable cause of the ventricular tachyarrhythmia and evaluation of other surgical needs of the patient, as well as consideration of the interactive effects of pacemakers and concurrent pharmacologic therapy postoperatively.

Adolescent↗
PubMed1984

Clinical performance of the implantable cardioverter-defibrillator.

The automatic implantable cardioverter-defibrillator has been implanted in 276 patients with ventricular tachyarrhythmias refractory to therapy with a follow-up period up to 50 months (average 9.75 months). The functional performance of the device has so far been most encouraging. The risks and complications associated with its use are acceptable and quite similar to those observed in patients with implanted pacemakers. Acceleration of ventricular tachycardia to a faster rhythm or to ventricular fibrillation is dealt with successfully through recycling. Actuarial analysis indicates that the device has a significant impact on the survival rate of the implantees, reducing the one-year mortality rate attributed to arrhythmias to only 2%.

Actuarial Analysis↗
PubMed1984

Surgical techniques for implanting the automatic implantable defibrillator.

Since February 1980, the automatic defibrillator was implanted in 77 survivors of multiple cardiac arrest. The subxiphoid technique was used in 28 patients and the thoracotomy technique was used in 20 patients with previous cardiac surgery. Median sternotomy was used in 29 patients undergoing open heart procedures as well as defibrillator implantation. While the subxiphoid is the most benign procedure employed, all are safe and well tolerated. The method used is determined by the clinical picture. Survival studies indicate improved survival in this high risk population.

Adolescent↗
PubMed1984

Use of the automatic implantable cardioverter-defibrillator in the treatment of malignant ventricular tachyarrhythmias.

Since February, 1980 nearly 200 automatic cardioverter - defibrillators have been implanted in patients with malignant ventricular arrhythmias. The currently-employed device weighs 298 grams and occupies a volume of 162 cm3. There are two defibrillation electrodes which also serve as sensors: one, an intravascular catheter placed in the superior vena cava at the level of the right atrium; the other, a flexible rectangular patch placed extrapericardially over the apex of the heart. Additionally, there is a bipolar right ventricular electrode for rate counting and R-wave synchronization which will eventually be used for pacing as well. The unit is powered by lithium batteries with a projected monitoring life of three years, or the capability of discharging approximately 100 times. The arrhythmia detector activates the cardioverter -defibrillator about 15 to 20 seconds after diagnosing a "treatable" arrhythmia, identified on the basis of a striking absence of isoelectric potential segments characteristic of ventricular fibrillation and many ventricular tachycardias. The diagnosis also requires fulfillment of individually-programmed heart rate criteria. If the initial discharge of 25 joules is ineffective, the device will recycle as many as three times with a final pulse of up to 42 joules. Of the twelve nonsurvivors among the initial 52 implantees who underwent implantation through September, 1982, only four deaths were unwitnessed and considered to be sudden and arrhythmic; the other eight deaths were due to heart failure or unrelated causes. Thus, from a predicted mortality of 48% in the same group of patients if the automatic defibrillator had not been implanted, the "sudden death" mortality was reduced to 8.5%.

Electrocardiography↗
PubMed1984

Mediastinal tap as useful method for the early diagnosis of mediastinal infection.

The simple and quick technique of mediastinal aspiration (mediastinal tap) can facilitate the early diagnosis of mediastinitis in the postoperative cardiac surgical patient. This technique offers objective evidence of mediastinal infection before the development of wound drainage or sternal instability, or both.

Bacterial Infections↗
PubMed1983

Clinical evaluation of the internal automatic cardioverter-defibrillator in survivors of sudden cardiac death.

An R-wave synchronous implantable automatic cardioverter-defibrillator (IACD) was evaluated in 12 patients with repeated episodes of cardiac arrest who remained refractory to medical and surgical therapy. Seven men and 5 women, average age 61 years, surgically received a complete IACD system. Coronary artery disease was found in 11 and the prolonged Q-T syndrome in 1. The average ejection fraction was 34%, and 6 patients had severe congestive heart failure (New York Heart Association class III or IV). The IACD is a completely implantable unit consisting of 2 bipolar lead systems. One system uses a lead in the superior vena cava and on the left ventricular apex through which the cardioverting pulse is delivered. The second system employs a close bipolar lead implanted in the ventricle for sensing rate. After the onset of ventricular tachycardia or fibrillation, the IACD automatically delivers approximately 25 J. Postoperative electrophysiologic study in 10 and spontaneous ventricular tachycardia in 1 patient demonstrated appropriate IACD function and successful conversion in all with an average of 18 +/- 4 seconds. The induced arrhythmias were ventricular tachycardia (160 to 300 beats/min) in 9 and ventricular fibrillation in 1. These data demonstrate that ventricular tachycardia, not ventricular fibrillation, was the predominant rhythm induced during programmed ventricular stimulation in these survivors of cardiac arrest and that the IACD effectively responded to a wide range of ventricular tachycardia rates as well as ventricular fibrillation. Use of the IACD offers an effective means of therapy for some patients who otherwise may not have survived.

Aged↗
PubMed1983

Automatic defibrillation in man: is it feasible?

Twenty-eight patients who survived multiple arrhythmic cardiac arrest refractory to medical therapy underwent implantation of the automatic defibrillator without additional antiarrhythmic surgery. Lateral thoracotomy was used for implantation in 14 patients and the subxiphoid technique was used in 14. There was no operative mortality and surgical complications were minimal. The longest follow-up was 29 months and the average was 14 months. The implanted device correctly identified and reverted 50 episodes of spontaneous malignant ventricular tachyarrhythmias in six hospitalized patients. After discharge, 20 episodes of automatic out-of-hospital resuscitations occurred in eight patients. Kaplan-Meier survival curves, based on the assumption that out-of-hospital defibrillations would otherwise have been lethal, indicated an expected 1 year mortality of 60 percent. Seven deaths were in fact observed in this period for an actual mortality rate of 30 percent. We conclude that automatic defibrillation is clearly feasible in man and appears to increase survival in selected high-risk patients.

Actuarial Analysis↗
PubMed1983

Use of alternating current during diagnostic electrophysiologic studies.

When conventional programmed electrical stimulation did not yield ventricular arrhythmias suitable for testing implanted automatic defibrillator function and for mapping the location of arrhythmogenic foci, full-wave rectified alternating current (120 Hz) was used for inducing arrhythmias. Application of alternating current resulted in ventricular tachycardias 31 times; in 27 instances, these tachycardias were similar in rate (216 +/- 37 beats/min) and morphology to those previously induced in the same patient by programmed electrical stimulation (191 +/- 30 beats/min). During endocardial mapping, the origin of the tachycardias induced by both methods was found in the same region. Alternating current produced ventricular fibrillation only four times, twice when it was the patient's spontaneous native arrhythmia and twice after apparently effective endocardial resection. No complications of the technique were observed. The use of alternating current was found to be simple, rapid and safe; it may be especially useful in the operating room during antiarrhythmic surgery because it markedly reduces the cardiopulmonary bypass time required for induction and may also be useful for testing the adequacy of endocardial resection.

Adolescent↗
PubMed1983

Mortality in patients with implanted automatic defibrillators.

Fifty-two patients who survived several arrhythmic cardiac arrests had implantation of an automatic defibrillator along with additional cardiovascular surgery as indicated. The mean follow-up was 14.4 months and the longest was 3 years. In the hospital, the implanted devices identified and reverted 82 episodes of spontaneous and 81 of 99 episodes of induced malignant tachyarrhythmias. There were 62 automatic resuscitations in 17 patients outside the hospital. Twelve patients died; four of the deaths were not witnessed. These deaths represent a 22.9% total and 8.5% sudden-death 1-year mortality rate. Because the expected 1-year mortality in patients without the automatic defibrillator was calculated to be 48%, there was an estimated 52% decrease in anticipated total deaths. The automatic implantable defibrillator can identify and correct potentially lethal ventricular tachyarrhythmias, leading to a substantial increase in 1-year survival in properly selected high-risk patients.

Adolescent↗
PubMed1983

Coronary heart disease and bypass surgery in urban blacks.

Myocardial revascularization was reviewed in 56 urban black patients (41 men, 15 women). The age range was 33 to 70 with a mean of 53. Fifty percent presented with class III angina and 50 percent had progressed to severe unstable angina. Cardiac catheterization revealed severe triple-vessel disease in 75 percent of the patients while 15 percent had double-vessel disease and only 9 percent had single-vessel disease.At surgery the average number of bypass grafts performed was 2.3. The operative mortality was 3.4 percent for the group with stable angina and 15 percent for the unstable group.At follow-up, 73 percent of the patients had no angina. Sixteen percent were improved and 11 percent continued to have angina. In spite of the presence of advanced coronary artery disease, myocardial revascularization can be accomplished with acceptable operative risks and good results in symptomatic urban blacks. The risk, however, is higher in patients who have already progressed to unstable angina. It is therefore imperative that operative intervention be carried out at an earlier stage of the disease if satisfactory results are to be realized in this group.

Adult↗
PubMed1983

Left ventricular aneurysmectomy. Factors influencing postoperative results.

One hundred consecutive patients who underwent resection of aneurysms of the left ventricle were reviewed. Eighty-four of these patients had resection or plication of an aneurysm of the anterior left ventricular wall either alone or in combination with coronary artery bypass grafting. In 27 patients who had little or no congestive heart failure, the primary indication for operation was disabling angina pectoris. In them the early mortality was 4% and late mortality, 4%. In nine other patients the primary indication for operation was life-threatening ventricular arrhythmias. In this group the early mortality was 56% and late mortality, 0%. Severe congestive heart failure was the primary indication for aneurysmectomy in 48 patients. In these patients the early mortality was 21% and late mortality, 34%. When the primary indication for operation was severe congestive heart failure, overall survival and postoperative results were best in patients in whom the nonaneurysmal left ventricle had good function preoperatively and was supplied by coronary arteries either unobstructed or favorable for bypass grafting; results were poorest in those patients with three-vessel coronary artery disease who had impaired motion of the lateral left ventricular wall and distal lateral wall vessels that were unfavorable for bypass grafting. It is concluded that patients with left ventricular aneurysms form a heterogeneous group in which the prognosis varies markedly. The probability of a good postoperative result can be predicted by careful preoperative analysis of a patient's symptoms, ventricular function, and coronary artery anatomy.

Adult↗
PubMed1983

Trials of the automatic implantable defibrillator in man. A three-year program report.

Since February, 1980, 65 survivors of multiple arrhythmic cardiac arrests unresponsive to therapy were referred for implantation of the automatic defibrillator. In 37 patients (Group I), automatic defibrillator implantation alone was performed by subxiphoid insertion (20 patients) or thoracotomy (17 patients). In another 28 patients (Group II), implantation was combined with definitive cardiac procedures--coronary artery bypass grafting in seven patients, bypass grafting and mitral valve replacement in four patients, and left ventricular aneurysmectomy with endocardial resection in 17 patients. There were no surgical deaths in Group I; four operative deaths occurred in Group II. The longest follow-up has been 34 months, average 15.6 months. Following hospital discharge, 44 episodes of automatic out-of-hospital resuscitation were observed in 11 Group I patients. Similarly, four resuscitations were observed in two Group II patients. Hypothetical survival curves based on the assumption that these out-of-hospital resuscitations were lifesaving indicated expected 1 year survivals rates of 45% in Group I and 85% in Group II. Excluding the perioperative deaths that were unrelated to the defibrillator, the actual 1 year survival rates observed were 75% and 95% in Groups I and II, respectively. Although definitive operation markedly reduced the number of out-of-hospital arrhythmic episodes, the automatic defibrillator appears to increase survival both when implanted alone and when used in combination with cardiac procedures.

Adolescent↗