Nan Earle

Spontaneous Ventricular Tachycardia Treated by Antitachycardia Pacing

: The database of the registry for an implantable cardioverter defibrillator was analyzed to determine the efficacy and safety of antitachycardia pacing for the termination of ventricular tachycardia. In 22,339 episodes treated, termination occurred in 94% and acceleration in only 1.4%.

Evolution of Surgical Techniques for Aneurysms of the Descending Thoracic Aorta: Twenty‐Nine Years Experience with 659 Patients

Between 1953 and 1993, 659 patients underwent descending thoracic aneurysm resection. The most common etiology was atherosclerosis. Pain was the main presenting symptom. Perioperative mortality fell from 24.2% between 1953 and 1964 to 14.3% between 1970 and 1993. Paraplegia occurred in 4.1% (27/659) patients overall and was little affected by time of operation or use of atriofemoral bypass. Paraparesis occurred in 5.9% (39/659) patients and was reduced by use of atriofemoral bypass. The low rate of paraparesis in the earlier experience was offset by the higher perioperative mortality from hemorrhage, attributable to the use of systemic heparin. The use of heparin‐free circuits with centrifugal pumps should be considered in patients likely to have a clamp time greater than 30 minutes. The major source of perioperative morbidity and mortality was cardiac causes (48%) followed by perioperative hemorrhage (14.4%), pulmonary complications (14.4%), and rupture of another aneurysmal segment (12.0%). Late mortality occurred most commonly from cardiac causes (30.6% of deaths) and rupture of another aneurysm (16.3% of deaths). Improvement in results was due to general refinements of management in all areas rather than any single factor. These results indicate that complete preoperative assessment of the patient and the entire aorta is essential and that regular life‐long follow‐up is critical in order to avoid unnecessary morbidity and mortality from cardiac, cerebrovascular, or subsequent aneurysmal complications. (J Card Surg 1994;9:648–661)

Long-term results of coronary bypass surgery. Analysis of 1698 patients followed 15 to 20 years.

Between 1968 and 1975, 1698 patients underwent coronary artery bypass with autogenous saphenous vein and were followed for up to 20 years. Age at operation was 53.9 +/- 8.4 years, and 1485 were men (88%). Angina was present in 1637 patients (96%). There was single-vessel disease in 306 patients (18%), double-vessel in 642 (38%), triple-vessel in 550 patients (32%) and left main stenosis in 200 (12%). Preoperative left ventricular quality was good in 1185 (70%), poor in 508 (30%), and unknown in five patients. Survival at 20 years was as follows: for single-vessel disease, 40%; double-vessel, 26%; triple-vessel, 20%; and left main, 25%. At 20 years of follow-up, 67% of surviving patients were asymptomatic and 26% were improved. Antianginal drug therapy consisted of nitrates in 49% of patients and beta-blockers in 26%. Graft patency at 0 to 5 years was 633 of 780 grafts (81%); at 6 to 10 years, 415 of 606 grafts (68%); at 11 to 15 years, 271 of 449 grafts (60%); and at 16 to 20 years, 65 of 140 grafts (46%). Coronary bypass reoperation was performed in 324 patients (19%) and survival of these patients was 62% compared to 37% for nonreoperation patients (p less than 0.05). Cox analysis demonstrated that the major determinants of survival related to age at operation, extent of coronary disease, quality of ventricle, history of stroke, and preoperative congestive heart failure. At 20 years of follow-up of this early experience with coronary bypass, 76% of surviving patients had one or more patent grafts and the probability of freedom from reoperation was 0.62.

Long-term fate of the aortic root and aortic valve after ascending aneurysm surgery.

ObjectiveThe authors determined in which patients tube graft replacement could be used. Summary Background DataTube graft replacement of ascending aortic aneurysms requires no coronary anastomoses and preserves the native aortic valve, but aortic insufficiency or aortic root aneurysms may develop requiring reoperation. Use of Bentall or Cabrol composite valve graft procedures obviates these problems but requires prosthetic valve replacement and coronary reattachment, both of which are associated with complications. These two procedures have been applied increasingly but because of renewed interest in aortic valve preservation and reconstruction, the authors determined in which patients tube replacement could be used. MethodsThe authors analyzed the fate of 277 patients, mean age 49 ± 14 years, operated on between 1953 and 1992 by techniques that preserved the aortic root. The most common pathology was atherosclerosis in 104 patients. Perioperative mortality since 1975 was 14%. ResultsFifteen patients required reoperation on the ascending aorta or aortic root: ascending aneurysm reoperation (6 patients); aortic valve replacement (8 patients), and a combined procedure (1 patient). Of these 15 patients, 8 had Marians syndrome, 10 had dissections, and 5 had medial degeneration/necrosis. ConclusionsSimple tube graft replacement of the ascending aorta was a durable technique in patients without Marfans syndrome or medial degeneration/necrosis and allowed preservation of the native aortic valve in many patients.

Outcomes in single versus bilateral internal thoracic artery grafting in coronary artery bypass surgery.

The authors analyzed the early outcomes in two groups of patients undergoing coronary artery bypass grafting (CABG) with single versus bilateral internal thoracic arteries (ITA) in their institution. One thousand sixty-nine patients underwent CABG with single or bilateral ITAs from 1990 to 2000. Of these patients, 911 (85.2%) had single ITA and 158 had bilateral ITA (14.8%). The incidence of tobacco abuse was 40.3% in the single ITA group and 56.7% in the double ITA group (P = 0.0001). The incidence of perioperative myocardial infarction, renal failure, reoperation for bleeding, stroke, or operative mortality did not differ in the two groups. There was a 4.4% incidence of mediastinitis in the bilateral ITA group versus 2.2% in the single ITA group (P = 0.0602). Early outcomes after bilateral ITA grafting for CABG are similar to single ITA grafting. Careful judgment should be exercised in selecting patients for bilateral ITA grafting, particularly if the patient smokes.

Acute impairment of coronary blood flow by dynamic cardiomyoplasty

The aim of this study was to quantify the effects of three different configurations of cardiomyoplasty on coronary blood flow in an acute dog model. Thirteen dogs had both latissimus dorsi muscles harvested and transposed to the chest. Coronary blood flow was measured using Doppler cuff probes on the left anterior descending and circumflex coronary arteries during each of three cardiomyoplasty configurations: left posterior, right anterior, and double. Multiple beat measures were made of systolic and diastolic flow during a control protocol and a subsequent protocol with the muscle(s) paced. Significant flow reductions during pacing were observed in the left anterior descending coronary artery during left posterior (17%, p = 0.003), right anterior (29%, p < 0.0001), and double (35%, p = 0.0001) myoplasty. Similar reductions occurred in the circumflex artery (14%, p = 0.0009; 20%, p = 0.001; 27%, p = 0.0053). The net flow over an entire pacing cycle also was reduced significantly: left anterior descending artery (11%, p = 0.0035; 23%, p = 0.0001; 23%, p = 0.0047) and circumflex artery (10%, p = 0.0025; 17%, p = 0.0018; 21%, p = 0.0091). Thus, in the acute setting cardiomyoplasty depresses coronary blood flow. A chronic setting will be needed to determine the ultimate significance of these results.

Hemodynamic effects of different pacing ratios in chronic dynamic double cardiomyoplasty

BACKGROUND Dynamic cardiomyoplasty is being used clinically worldwide, and evaluated by a clinical trial (phase III) in the United States. Some centers stimulate the skeletal muscle wrap with every heart beat (1:1 [muscle:heart]), whereas others use every other heart beat (1:2). Recent concern over the possible deleterious effects of too-frequent stimulation of the muscles motivated the attempt to evaluate, in a canine model of chronic, double cardiomyoplasty, the effects of two different pacing ratios on several hemodynamic parameters of interest. METHODS Double cardiomyoplasty was performed using both latissimus dorsi muscles in 11 dogs. Fatigue resistance was achieved using the clinical transformation protocol. At a final experiment, acute cardiac failure was induced by administration of propranolol. Hemodynamic measurements of eight physiologic variables were averaged over complete pacing cycles, including the nonpaced beat at a 1:2 pacing ratio. RESULTS The net effects of latissimus dorsi muscle stimulation at each of two pacing ratios were compared using nonparametric statistics. With the exception of left ventricular pressure (p = 0.0262) and its first derivative, dP/dt (p = 0.0099), there was no significant difference between hemodynamic performance at the two pacing ratios. CONCLUSIONS In this canine model, pacing every other beat produces hemodynamic results that are statistically similar to pacing every beat. Less frequent stimulation of the latissimus dorsi muscle may preserve its function and improve clinical results without compromising hemodynamic benefit.

Late Changes in Saphenous Vein Aorto-Coronary Bypass Grafts: Clinical, Angiographic, Lipid and Pathological Correlations

Coronary bypass surgery has become well established as the most effective form of treatment for relief of angina pectoris and has been shown, in a number of ramdomized studies, to prolong life in certain subsets of patients. Despite the extraordinary success of this operation and its durability in comparison to other forms of operations for atherosclerosis, there is need for enhancement of early and late graft patency and prevention of the late vein graft deterioration which has been observed in a significant portion of patients over a period of 10 to 15 years.