James R. Malm

Electrophysiologic properties and response to pharmacologic agents of fibers from diseased human atria.

SUMMARY We used standard nicroketrode to record action potentials of human right trial fibers obtained during cardiac surgery, and correlated these potential with dinical and preoperative ECG data. Human atrial fibers were classified as follows: Group A (ten patients) had a maximum diastolic potential (MDP) of −71.4 ± 5.1 mV (mea ± SD), and actin potentials that were primarily fast pe These atria were normal or sdghty dilated. In group B (12 patients) MDP was −50.3 ± 5.7 mV; action potentials were slow responses and the atria were moderately to markedly dilated. Atrial arrhythmias occued in four grop B and no group A patients. The ECG revealed a signfcant (P < 0.005) in P wave duration: group A, 89 ± 3.0 nec; B, 111 ± 6.0 msec. Verapamil, 0.1 mg/L, markedly depre roup B action potentials. Verapamil, 0.1–1.0 mg/L, de only the action potential plateau of group -A. Procanamlde 1–100 mg/L had equivalent effects on fibers of both groups A and B, effects whc were small at dosages of less than 40 mg/L. Procalnamide did ot depress slow response automaticity, but verapamil (0.1–1 mg/L) did.

Bypass Grafts for Recurrent or Complex Coarctations of the Aorta

Twenty-three patients aged 5 to 53 years with recurrent or complex coarctations of the aorta were successfully operated upon using bypass grafts. This technique of repair was selected for 5 patients with recurrent coarctation, 11 with long-segment coarctation with or without hypoplasia of the transverse aortic arch, and 7 with inadequate collateral circulation. Nineteen patients had bypass grafts from the left subclavian artery to the distal descending thoracic aorta. The other 4 had a combined approach through a left thoractomy and median sternotomy with grafts between the ascending and descending thoracic aorta. All patients survived the operative procedure. One patient were reexplored for a hemothorax and 5 developed transient postoperative hypertension. There were no instances of abdominal vasculitis or lower extremity paralysis. These patients have been followed from 3 months to 11 years postoperatively, and all but 1 are alive and well. Twenty-two are normotensive, and none have the sequelae of hypertensive disease. Gradients up to only 15 mm Hg exist between upper and lower extremity blood pressures. Five patients have undergone postoperative catheterization and aortography, and all have patent grafts. This procedure is a useful and adjunct in difficult coarctations of the aorta and can be safely performed with excellent reproducible long-term results.

Adjustable Annuloplasty for Tricuspid Insufficiency

De Vega described a technique for tricuspid annuloplasty using synthetic suture to reduce the size of the dilated annulus. We present our experience with an adjustable modification of de Vegas suture annuloplasty technique. The records of 12 patients followed for 15 to 30 months were reviewed. All 10 survivors had a significant drop in right-sided filling pressure (average, 39% decrease) and an associated improvement in clinical status. The 2 deaths in the series were not related to persistent tricuspid insufficiency. This technique represents a reliable, rapid, and readily teachable method for the surgical management of tricuspid insufficiency.

Alpha and beta adrenergic effects on human atrial specialized conducting fibers.

We determined the effects of epinephrine on automaticity and action potential characteristics of right atrial specialized fibers (RAF) from human atria obtained during cardiac surgery. RAF were studied with standard microelectrode techniques during superfusion with Tyrodes solution at 37°C. A biphasic response to epinephrine was seen, rate slowing at low agonist concentrations and increasing at high concentrations. The epinephrine-induced slowing of spontaneous rate was due to a decrease in the slope of phase 4 depolarization. At the high epinephrine concentrations RAF hyperpolarized. The a-adrenergic blocker, phentolamine, shifted the dose-response curve upward and to the left and enhanced the hyperpolarization of RAF. The /3 blocker, propranolol, shifted the curve to the right and decreased the degree of hyperpolarization. Our study suggests the presence of a and, B receptors in RAF. The a response consists of a slowing of rate, the # response of an acceleration of rate and hyperpolarization of RAF.

The Oxygen Cost of Breathing Following Anesthesia and Cardiac Surgery

The amount of oxygen consumed by respiratory muscles during spontaneous respiration was measured in ten patients immediately following mitral valve replacement. The cost of breathing was calculated as the difference (Δ02) between mean &OV0312;02‘s measured during spontaneous and mechanical ventilation. In every patient, mean &OV0312;02 was greater during spontaneous than during mechanical ventilation; 150.5 = 8.1 ml/m2/min (mean = SE) vs. 121.1 = 6.0 ml/m2/min. The mean Δ&OV0312;02, or oxygen cost, was 29.7 = 6.6 ml/m2/min (range 3.8–64.6 ml/m2/min), which represents 18.6 per cent of &OV0312;02 utilized by respiratory muscles, as opposed to the accepted norm of 1–3 per cent. This cost was predictable from preoperative vital capacity; the lower the vital capacity (expressed as per cent predicted vital capacity), the greater the oxygen cost of breathing. The results confirm one beneficial aspect of mechanical ventilation during the immediate postoperative period, in climinaling the oxygen cost of breathing and reducing total &OV0312;02.

Cardiac Valve Replacement in Children: A Twenty-Year Series

Ninety-four children ranging from 3 months to 19 years of age underwent cardiac valve replacement at Columbia Presbyterian Medical Center from 1965 to 1985. The overall operative mortality was 12%, but mortality was higher among patients less than 2 years of age, patients who had had previous cardiac operations, and patients requiring double-valve replacement. Seven of 11 patients who received mechanical valves and no anticoagulation experienced major thromboembolic events. An episode of gastrointestinal hemorrhage that was easily controlled represents the only bleeding complication in the entire series. Valve replacement in children continues to be a high-risk procedure, and efforts to preserve native valve function should be attempted when technically feasible. Our data also suggest that anticoagulation can be safely accomplished in the pediatric age group and should be employed in patients requiring placement of a mechanical prosthesis, especially in the mitral position.

Muscular ventricular septal defects repaired with left ventriculotomy

Between 1974 and 1979 nine patients, aged 10 months to 4 years, underwent left ventriculotomy for closure of single or multiple defects in the muscular ventricular septum. The vertical incision paralleled the anterior descending branch of the left coronary artery near the apex of the left ventricle and ranged from 2.5 to 3.5 cm in length. Four patients also had a right ventriculotomy with closure of a high perimembranous ventricular defect in two. Serial electrocardiograms indicated changes of myocardial ischemia or necrosis. Left bundle branch block did not develop in any patient. Three patients died in the early postoperative period. The six surviving patients are living and well 2 to 7 years later. There is apparent complete closure of the ventricular defects, which was documented by cardiac catheterization in four cases. Two patients had cardiomegaly and left ventricular dysfunction as assessed with echocardiographic and angiographic study, whereas four displayed good cardiac function. In three of the latter patients, cardioplegia or deep hypothermia techniques were utilized intraoperatively. The observations indicate that left ventriculotomy of limited size is an acceptable approach to the difficult problem of repair of muscular ventricular defects but may involve some risk of compromise of the coronary circulation.

Cor triatriatum sinistrum: one institution's 28-year experience

SummaryTwelve patients with cor triatriatum sinistrum were treated over a 28-year period. Their ages ranged from 1 month to 7.5 years. Congestive heart failure was the most common presentation. Cardiac catheterization was performed on six of the 12 patients and a correct diagnosis of cor triatriatum was made on angiography in only four of the six. Of the remaining six patients, three were diagnosed as having cor triatriatum by echocardiography and three by autopsy. Echocardiography is now considered to be the diagnostic modality of choice in our institution. Seven patients were operated on and five died prior to diagnosis or treatment. Associated cardiac anomalies included persistent left superior vena cava, atrial septal defects, coarctation of the aorta, and total anomalous pulmonary venous drainage. A right atrial, transseptal approach to the common pulmonary chamber and excision of the left atrial membrane was found to be the treatment of choice and was used in six of the seven patients operated on. One patient died in the postoperative period. Thus, cor triatriatum sinistrum, a rare and potentially lethal congential cardiac anomaly, can be diagnosed by echocardiography and successfully treated surgically with a low operative mortality.

Postoperative Hypoxemia: Contribution of the Cardiac Output

When venous admixture and oxygen consumption remain constant, a decrease in cardiac output will necessarily decrease arterial oxygenation. To test this as a cause of postoperative hypoxemia, hemodynamic and respiratory gas exchange measurements were made in 14 patients before and after open repair of acquired cardiac valvular disease. Cardiac output was measured by dye-dilution. True shunt (JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngS/JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngT) breathing 100 per cent O2 and venous admixture (JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngVA/JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngT) breathing air were measured. A relationship between cardiac index (C.I.) and arterial oxygen saturation (SaO2) was established for groups with JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngVA/JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngT 0–10 per cent and 10–20 per cent. A decrease in C.I. produced a decrease in arterial oxygenation with JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngVA/JOURNAL/anet/04.02/00000542-197002000-00011/ENTITY_OV0422/v/2017-07-22T055310Z/r/image-pngT constant.

Surgical repair of congenitally corrected transposition of the great arteries: results and follow-up.

Eighteen patients with congenitally corrected transposition of the great arteries had open heart repair for intracardiac associated defects. Fourteen patients (78%) are alive during the follow-up period (mean 4.5 years). Seventeen (94%) of the 18 patients had ventricular septal defect closure, and 12 (66%) insertion of a pulmonary artery conduit. Surgical repair of the tricuspid valve was required in 6 patients (33%) during the first operation and in 3 additional patients during a second operation (total 50%). When hemodynamic overload or cardiac compromise was detected after surgery it was directly related to identifiable residual defects such as atrioventricular valvular insufficiency, residual ventricular septal defect, or pulmonary conduit stenosis. Repeat open heart operation for residual defects was common during the follow-up period (8 of 18 patients, 44%). No patient showed primary systemic or pulmonary ventricular dysfunction during the follow-up period. None of the last 11 patients developed complete heart block. Postoperative intraventricular conduction defects were common and are presumably caused by surgical injury of the bundle branches. Our observations suggest that surgical repair of congenitally corrected transposition of the great arteries can be currently achieved with acceptable risk. Improved knowledge of the precise location of the specialized conduction system resulted in a marked decrease in the incidence of atrioventricular (A-V) block in patients with congenitally corrected transposition of the great arteries undergoing intracardiac repair. In the absence of postoperative residual defects it can be expected that longevity and quality of life will improve considerably, but many of these patients may require a repeat operation.