J. Gerard Mudd

Late Patency of the Internal Mammary Artery as a Coronary Bypass Conduit

From January, 1972, through August, 1977, 472 patients had internal mammary artery (IMA) coronary bypass, of which 100 were double-IMA bypasses. We selected those patients having a widely patent IMA one year postoperatively who then had a second catheterization 49 to 105 (mean, 64) months following operation. None of the 93 patients who met these criteria was specifically recalled for this study; they all had follow-up catheterizations for multiple other reasons. All of the 91 left IMA and 22 right IMA bypasses (total, 113) were patent at late catheterization, but 1 right IMA was diffusely narrowed. One left IMA had acute angulation with 50% stenosis proximal to the distal anastomosis, which was unchanged over the follow-up interval. There were 100 patent saphenous vein bypasses at one year and 87 at late catheterization. Late closure of coronary bypass grafts is secondary to progression of coronary disease, atherosclerosis of the bypass conduit, or intimal proliferation. Because we have not encountered the latter two causes of conduit closure, IMA grafts remain our graft of choice for nonemergent operations in patients under 60 years of age having revascularization of the left anterior descending coronary artery system.

Ebstein's anomaly∗

Ebstein’s anomaly is a malformation of the tricuspid valve with myopathy of the right ventricle (RV) that presents with variable anatomic and pathophysiologic characteristics, leading to equally variable clinical scenarios. Medical management and observation is often recommended for asymptomatic patients and may be successful for many years. Tricuspid valve repair is the goal of operative intervention; repair also typically includes RV plication, right atrial reduction, and atrial septal closure or subtotal closure. Postoperative functional assessments generally demonstrate an improvement or relative stability related to degree of RV enlargement, RV dysfunction, RV fractional area change, and tricuspid valve regurgitation. Figure 1. Tricuspid valve displacement highlights rotation of tricuspid annulus towards the right ventricular outflow tract in addition to downward/apical displacement. ARV: atrialized right ventricle; RA: right atrium; TRV: true right ventricle. Copyright

Anomalous inferior vena cava

Abstract Eight patients have been presented with a malformation of the inferior vena cava. The prerenal portion (the portion between the kidney and right atrium) of the inferior vena cava is absent and replaced by the enlarged azygos vein, which opens into the superior vena cava at its usual position. The hepatic venous blood drains directly into the right atrium. This anomaly is referred to in the literature as “absent” inferior vena cava. The embryological development has been described and seems to indicate that the postrenal (lumbar) portion of the inferior vena cava in this entity is more likely normal. Therefore, it is suggested to abandon the term “absent” inferior vena cava in favor of anomalous inferior vena cava with a description of the specific anomaly present. The frequency of this malformation in our laboratory was 1.3 per cent and is attributed to the fact that cardiac catheterization is performed by way of the long saphenous or superficial femoral veins. The diagnosis of an anomalous inferior vena cava might be suspected when the antero-posterior roentgenogram reveals a rounded density in the right superior mediastium representing the enlarged azygos vein as it enters the superior vena cava. When during cardiac catheterization the excursions of the catheter in the area of the right atrium are restricted, an anomalous inferior vena cava should be considered, especially if the oxygen saturations remain identical in what is thought to be the inferior vena cava, right atrium and superior vena cava. The path of the catheter will usually be diagnostic since it cannot enter the right atrium without first passing downward by way of the superior vena cava. Angiocardiography will definitely reveal the presence of this malformation. Open-heart surgery for other cardiac lesions that are usually present with diversion of the venous return to a pump and oxygenator may be extremely difficult. One additional patient has been described with a normal inferior vena cava and a patent azygos vein originating at the renal level and emptying into the superior vena cava at its usual place.

Enhanced transcardiac I-norepinephrine response during cold pressor test in obstructive coronary artery disease

Studies during the past decade have demonstrated that sympathetic nervous activity can play an important role in the regulation of coronary blood flow. It became apparent that alpha adrenergic mediated coronary vasoconstriction can compete with metabolically-induced coronary vasodilatation, particularly in myocardial regions with decreased coronary reserve [1–7]. Recent studies have also emphasized that increased sympathetic nervous activity enhanced ventricular irritability and lowers the threshold to ventricular fibrillation in the ischemic myocardium [8–11]. Since these observations suggest that increases in sympathetic nervous activity could place the patient with obstructive coronary artery disease at increased risk, we measured arterial and coronary sinus 1-norepinephrine contents during relatively mild sympathetic stress in this patient category and compared their response of transcardiac 1-norepinephrine pattern to that in patients with normal coronary arteries. We selected cold pressor stimulation because it is probably similar to the level of sympathetic stress experienced frequently during daily life. Our data indicate that there is a substantially greater increase in coronary sinus 1-norepinephrine concentrations in the patients with obstructive coronary artery disease compared to those without disease.

Late Sequelae of Perioperative Myocardial Infarction

The late suquelae of myocardial injury occurring at the time of direct myocardial revascularization are unknown. Fifty of 500 consecutive patients undergoing aortocoronary bypass grafting developed both electrocardiographic and enzymatic evidence of myocardial injury. They were matched with 50 patients of similar age, sex, history of previous infarction, severity of angina, degree of coronary arteriosclerosis, and level of ventricular function as determined by preoperative angiographic studies. The conduct of the operation was identical in each group except for prolongation of total cross-clamp time in those patients with myocardial injury. The total number of vessels grafted, the conduit used, and the operative mean graft flow were similar. Results of treadmill stress testing at 24 to 36 months were not significantly different between groups. Angina status, long-term survival, graft patency, and ventricular function were not adversely affected by intraoperative myocardial injury. However, postoperative ventricular function and stress test performance were related to graft patency.

Aortic aneurysm in childhood: report of six instances.

Six instances of aortic aneurysm in children have been observed in the past 15 years. Four children with aortic stenosis and coarctation of the aorta had aneurysmal dilatation of the ascending aorta, and two children with coarctation of the aorta had ruptured post-stenotic dilatation of the descending aorta. Our observations suggest that aortic aneurysm can be the result of hemodynamic stress, although developmental anomaly of the aorta associated with aortic stenosis or coarctation could be responsible for the development of the aneurysm.

The natural and postoperative history of 252 patients with proved ventricular septal defects

Abstract In 252 patients the diagnosis of isolated ventricular septal defects was proved by cardiac catheterization and cineangiography. During a period of one to nine years, none of 163 patients with pulmonary systolic pressures below 50 mm. Hg showed any clinical evidence of progressive deterioration. Of the forty in this group undergoing serial catheterization studies, not one showed any evidence of progressive pulmonary hypertension, and two patients had spontaneous closure of the ventricular defect. It is concluded that patients with pulmonary pressures below 50 mm. Hg can be followed safely without surgical intervention, but continued close scrutiny of this group is extremely important and continued serial studies will eventually reveal the true natural history of patients in this category. The natural course of thirty-six patients with pulmonary systolic pressure above 50 mm. Hg is discouraging. Serial studies in thirteen patients showed a reduction in pulmonary pressure in only five, in two right ventricular outflow hypertrophy developed and in one a coarctation of the aorta was repaired; the rest continued to show signs of severe pulmonary hypertension. Eight patients have died. Direct surgical repair of the ventricular defect has been accomplished with varying degrees of success. The early mortality rate fluctuates with the degree of pulmonary hypertension, the changes in atrioventricular conduction damage and the competence of the surgical team. Each Center must therefore recommend surgical repair according to its own particular abilities when the hemodynamic conditions warrant intervention. The long-term results of successful surgical or spontaneous closure of the defect are still unknown, and must be followed closely to establish the eventual life expectancy.

Myocardial revascularization: a rebuttal of the cooperative study.

From January 1972 through December 1974, at Saint Louis University Medical Center (SLU), 345 patients similar to those of the VA Cooperative Coronary Artery Study received CABG. Operative mortality was SLU 2.3%, VA 5.6% (p < 0.05). Perioperative myocardial infarction rate was SLU 8.4%, VA 18% (p < 0.005). One year graft patency was SLU 87%, VA 71%; all grafts patent SLU 76%, VA 54%; at least one graft patent SLU 96%, VA 89%. SLU angina pectoris relief at five years was 90%. SLU patients free of myocardial infarction five years postoperatively was 83%. Comparative cumulative four year survivals were

Revascularization of the right coronary artery

This study was undertaken to evaluate revascularization of the right coronary artery with regard to factors that enter into the decision to graft less significant lesions, such as graft flow, graft patency and progression of proximal disease. The results of grafting the right coronary artery were studied in 23 patients with lesions reducing luminal diameter by less than 50 percent (Group 1), 35 patients with luminal narrowing of 50 to 70 percent (Group 2) and 112 patients with greater than 70 percent luminal narrowing (Group 3). At operation there was no significant difference in saphenous vein graft flows among the three groups. Postoperatively the mean follow-up period was 20, 27 and 26 months, respectively. Graft patency was not significantly different among the three groups. Progression of the proximal lesion was studied and compared with that in 71 ungrafted right coronary arteries, 60 with less than 50 percent stenosis and 11 with more than 50 percent stenosis. Among vessels with less than 50 percent narrowing, the proximal lesion showed progression in 26 percent of the ungrafted vessels and in 83 percent of the grafted vessels (P less than 0.005); progression to total occlusion occurred in 3 percent of the former and in 28 percent of the latter (P less than 0.005). Progression to total occlusion was more frequently associated with a patent than with an occluded graft (P less than 0.05). The occurrence of significant progression in ungrafted vessels and the lack of effect on graft patency of the severity of the proximal disease suggest that revascularization of less significant lesions may be of value. However, the resultant increase in progression of proximal disease makes the patient dependent on the long-term patency of the vein graft.

Metabolic Assessment of Internal Mammary Artery Implantation in the Dog

The metabolic and physiologic contributions of an implanted internal mammary artery have been assessed in five dogs 24 to 34 months following internal mammary artery implantation and concomitant ameroid constrictor application to coronary arteries. All implants were patent angiographically prior to evaluation by right heart bypass and continual autoanalyzer assessment of myocardial oxygen, pyruvate, and lactate extraction. Control internal mammary artery flow averaged 17.5 ml/100 g LV/min. Occlusion of the internal mammary artery failed significantly to alter myocardial extraction of oxygen, pyruvate and lactate or ventricular function, nor did these patent implants prevent significant changes in oxygen, pyruvate, and lactate extraction and ventricular function during and following occlusion of a remaining patent left coronary artery. In only one animal did internal mammary artery flow increase with left coronary artery occlusion, and this only transiently. These results indicate that demonstration of angiographic patency of an internal mammary artery implant does not necessarily indicate significant metabolic or functional contribution of this extracardiac blood supply to the heart.