Levi Watkins

Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings.

THE development of a clinically applicable, automatic, implantable defibrillator has been described previously.1 This electronic device is designed to monitor cardiac electrical activity, to recogn...

Stroke following coronary artery bypass grafting: A ten-year study

To identify possible risk factors for the occurrence of stroke during coronary artery bypass grafting (CABG), the cases of 3,279 consecutive patients having isolated CABG from 1974 to 1983 were reviewed. During this period, the risk of death fell from 3.9% to 2.6%. The stroke rate, however, fell initially but then rose from 0.57% in 1979 to 2.4% in 1983. Adjustment of these data for age clearly demonstrated that the risk of stroke has increased largely because of an increase in the mean age of patients undergoing CABG procedures. A case-control study involving all 56 stroke victims and 112 control patients was used to identify those risk factors significantly associated with the development of stroke in univariate analysis: increased age (63 versus 57 years in stroke patients and controls, respectively; p less than 0.0001); preexisting cerebrovascular disease (20% versus 8%; p less than 0.03); severe atherosclerosis of the ascending aorta (14% versus 3%; p less than 0.005); protracted cardiopulmonary bypass time (122 minutes versus 105 minutes; p less than 0.005); and severe perioperative hypotension (23% versus 4%; p less than 0.0001). Other variables not found to correlate with postoperative stroke included previous myocardial infarction, hypertension, diabetes mellitus, lower extremity vascular disease, preoperative left ventricular function, and intraoperative perfusion techniques. Elderly patients who have preexisting cerebrovascular disease or severe atherosclerosis of the ascending aorta or who require extensive revascularization procedures have a significantly increased risk of postoperative stroke.

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.

Current indications, risks, and outcome after pericardiectomy

A retrospective analysis of the records of 60 patients who underwent pericardiectomy over a 10-year period (1980 to 1990) at The Johns Hopkins Hospital was performed. Indications for operation were effusive disease in 24 patients and constriction in 36 patients. Six patients (10%) with pericardial effusion had pain as the primary symptom necessitating intervention. The operative approach for pericardiectomy was median sternotomy in 52 patients (4 patients required cardiopulmonary bypass) and left anterior thoracotomy in 8 patients. Nine patients (5 with constriction and 4 with effusion) with a prior limited pericardial procedure required formal pericardiectomy. The operative mortality rate for pericardial effusion and constriction was 4.2% and 5.6%, respectively. Follow-up (median follow-up, 56.9 +/- 38.2 months) was obtained on 56 patients (93.3%). Actuarial survival at 1 year, 5 years, and 10 years for all patients was 82.1% +/- 5.1%, 71.7% +/- 6.7%, and 59.8% +/- 12.2%, respectively. A Cox proportional hazards regression analysis was performed using 20 clinical variables. A history of malignancy, previous pericardial procedure, and preoperative New York Heart Association class IV were found to be predictors of poor survival. All patients who underwent operation primarily for effusion with associated pain are alive and have improved functional capacity without steroid use. We conclude that pericardiectomy can be performed with low mortality and can result in good long-term survival and improved functional capacity. Patients who are seen primarily with pain refractory to steroid therapy can be relieved of symptoms with operation.

Routine use of the left internal mammary artery graft in the elderly

Left internal mammary artery (LIMA) grafts have better long-term patency rates than do saphenous vein grafts and result in improved late survival. The present study was undertaken to assess the results of LIMA grafting in the elderly. From 1980 through 1988, 723 patients 70 years of age or older had isolated coronary artery bypass grafting performed. During the first 5 years, only 11% of the elderly patients received LIMA grafts, whereas 86% having coronary artery bypass grafting since 1985 had LIMA grafts. Since 1986, LIMA use in the elderly has become routine, with 92% of patients receiving internal mammary artery grafts. During the first 5 years, elderly patients had a hospital mortality rate of 9.3%. Since 1985, the hospital mortality rate fell to 5.5%. In addition, the occurrence of major surgical complications was either unchanged or reduced in patients receiving LIMA grafts. Furthermore, late follow-up indicates a significantly improved 4-year survival rate in patients with internal mammary artery grafts compared with those without: 86 +/- 0.02% versus 77 +/- 0.03% (p less than 0.01). Analysis of multiple potential risk factors for early mortality was performed using multiple logistic regression and late survival using the Cox proportional hazards model. Although unmeasured predictor variables may confound retrospective analyses, LIMA grafting appears to be an independent predictor both of improved early and late survival.

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.

Neurologic injury in cardiac surgical patients with a history of stroke.

BACKGROUND Controversy still exists as to whether patients with previous stroke are at increased risk for neurologic complications after heart operations. METHODS We performed a prospective analysis of 1,000 consecutive patients undergoing cardiac operations requiring cardiopulmonary bypass, without hypothermic circulatory arrest. Of the 1,000 patients, 71 had previously documented stroke (study group); 2 control patients with no history of stroke were selected for each of these patients (control group, n = 142). There were no significant differences between the study and control patients with respect to established risk factors for neurologic complications. RESULTS Compared with controls, study patients took longer to awaken (12.6 +/- 10.9 versus 3.5 +/- 2.1 hours; p < 0.0001) and longer to extubate (29.5 +/- 29.3 versus 9.1 +/- 5.2 hours; p < 0.001), and had a greater incidence of reintubation (7 of 71, 9.9% versus 2 of 142, 1.4%; p < 0.01) and postoperative confusion (26 of 71, 36.6% versus 7 of 142, 4.9%; p < 0.001). There was a higher incidence of focal neurologic deficit among study patients (31 of 71, 43.7% versus 2 of 142, 1.4%; p < 0.001). These deficits included new stroke (6 of 71, 8.5%) as well as the reappearance of previous deficits (19 of 71, 26.8%) or worsening of previous deficits (6 of 71, 8.5%), without new abnormalities on head computed tomography or magnetic resonance imaging. Study patients with neurologic deficit had longer cardiopulmonary bypass times than did study patients without deficit (146 +/- 48.5 versus 110 +/- 43.3 minutes; p < 0.001). The 30-day mortality rate was greater in study patients than in controls (5 of 71, 7% versus 1 of 142, 0.7%; p < 0.02), with four deaths among the 6 study patients with a new stroke (66.7%). CONCLUSION This analysis identifies a group of patients at high risk for neurologic sequelae and confirms the vulnerability of the previously injured brain to cardiopulmonary bypass, as evidenced by reappearance or exacerbation of focal deficits in such patients.

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.

Aortic valve replacement in the elderly. Risk factors and long-term results.

OBJECTIVE The current study was undertaken to determine long-term results of aortic valve replacement (AVR) in the elderly, to ascertain predictors of poor outcome, and to assess quality of life. SUMMARY BACKGROUND DATA Aortic valve replacement is the procedure of choice for elderly patients with aortic valve disease. The number of patients aged 70 and older requiring AVR continues to increase. However, controversy exists as to whether surgery devoted to this subset reflect a cost-effective approach to attaining a meaningful quality of life. METHODS This study reviews data on 247 patients aged 70 to 89 years who underwent isolated AVR between 1980 and 1995; there were 126 men (51%) and 121 women (49%). Follow-up was 97% complete (239/247 patients) for a total of 974.9 patient-years. Mean age was 76.2 +/- 4.8 years. Operative mortality and actuarial survival were determined. Patient age, gender, symptoms, associated diseases, prior conditions, New York Health Association class congestive heart failure, native valve disease, prosthetic valve type, preoperative catheterization data, and early postoperative conditions were analyzed as possible predictors of outcome. Functional recovery was evaluated using the SF-36 quality assessment tool. RESULTS Operative mortality was 6.1% (15/247). Multivariate logistic regression showed that poor left ventricular function and preoperative pacemaker insertion were independent predictors of early mortality. After surgery, infection was predictive of early mortality. Overall actuarial survival at 1, 5, and 10 years was 89.5 +/- 2% (198 patients at risk), 69.3 +/- 3.4% (89 patients at risk), and 41.2 +/- 6% (13 patients at risk), respectively. Cox proportional hazards model showed that chronic obstructive pulmonary disease and urgency of operation were independent predictors of poor long-term survival. Postoperative renal failure also was predictive of poor outcome. Using the SF-36 quality assessment tool, elderly patients who underwent AVR scored comparably to their age-matched population norms in seven of eight dimensions of overall health. The exception is mental health. CONCLUSIONS Aortic valve replacement in the elderly can be performed with acceptable mortality. Significant preoperative risk factors for early mortality include poor left ventricular function and preoperative pacemaker insertion. Predictors of late mortality include chronic obstructive pulmonary disease and urgency of operation. These results stress the importance of operating on the elderly with aortic valve disease; both long-term survival and functional recovery are excellent.

Implantation of the Automatic Defibrillator: The Subxiphoid Approach

The automatic implantable defibrillator is an electronic device capable of diagnosing and correcting malignant venticular arrhythmias. While major thoracic surgery was required in the original 24 implants, a new technique for implanting the device has been developed. The first subxiphoid implantations have been accomplished with the defibrillatory function successfully tested intraoperatively. The advantages and indications of the subxiphoid technique are reviewed.