Effects of isolated right and left ventricular stretch on regional arteriolar resistance.

In order to evaluate right and left ventricular stretch receptors without concomitantly stimulating those of the contralateral ventricle, 12 dogs were placed on total cardiopulmonary bypass. Balloons connected to compliant reservoirs were introduced into the right and left ventricles. Changes in systemic, gracilis muscle, and paw perfusion pressure at a constant flow were used as indices of systemic, muscle, and cutaneous vascular resistance. To induce left ventricular stretch, the balloon in that chanber was rapidly inflated from a mean pressure of 1.33 kPa (10 mmHg) to a mean pressure of 7.32 kPa (55 mmHg) for 15s (6.00 kPa [45mmHg] increment). For right ventricular stretch, the pressure was increased from 0.67 to 4.00 kPa (5 to 30 mmHg) for 30 s (3.34 kPa [25 mmHg] increment). Both left and right ventricular stretch produced a significant fall in systemic (-4.92 kPa [-37 mmHg], -36%) and gracilis muscle (-5.59 kPa [-42 mmHg], -30%) perfusion pressure, with only minimal changes in cutaneous vascular resistance (-0.80 kPa [-6 mmHg], -4%). This reflex was found to be vagally mediated, to have a low threshold for stimulation (left ventricle, 0.67 kPa [5 mmHg] increment; right ventricle, 1.33 kPa [10 mmHg] increment), and to have a neurogenic sympathetic alpha-adrenergic efferent limb. The low threshold for stimulation suggests that these reflexes may play a physiological role with changes in body position and may be important in such pathological conditions as semilunar valvular stenosis and myocardial infarction.

Considerations in the development of artificial heart valve substitutes for use in infants in small children.

Experimental studies carried out in our laboratory suggest that it is possible to develop a family of stent-supported tissue valve substitutes suitable for use in tissue and annuli of the hearts of small children in tissue annulus sizes ranging from 12 to 22 mm. Either glutaraldehyde-preserved, stent-supported primate tissue aortic valves or tissue leaflet valves constructed from dura mater preserved in 98 per cent glycerine can be used. In both instances, hemodynamics assessment of the valve substitutes in a mock circulation indicated that function was acceptable at the cardiac outputs normal for infants and children during the first few years of life. Stent-supported dura mater valves 16 nm. in diameter have been used to replace the mitral valve in 2 infants 7 and 8 months of age with complete atrioventricular canal defects and mitral regurgitation, one of whom survives with demonstratable satisfactory hemodynamic function of the valve substitute.

Valve failure caused by cusp tears in low-profile Ionescu-Shiley bovine pericardial bioprosthetic valves.

The pathologic findings in two low-profile Ionescu-Shiley bioprostheses that failed because of cusp tears are presented. Both valves were in the mitral position, one in place 28 months and the other 40 months. Observation of the valves and their tears suggests that stress at the cusp alignment stitches may be important in the genesis of the tears.

Long-term clinical results with the Ionescu-Shiley pericardial xenograft.

From 1977 to 1987, 829 Ionescu-Shiley pericardial valves (Shiley, Inc., Irvine, Calif.) were implanted in 766 patients at the University of Ottawa Heart Institute. There were 476 patients who had aortic valve replacement, 234 who had mitral valve replacement, and 44 who had double valve replacement. The standard-profile design was used in 508 patients and the low-profile design in 321 patients. Follow-up was obtained for 97% of patients, with calculation of event-free probabilities. At 10 years the overall probability of freedom from structural failure was 48% +/- 7% after aortic valve replacement, 44% +/- 15% after mitral valve replacement, and 79% +/- 11% after double valve replacement. Although at 5 years the probability of failure was statistically lower with the low-profile design, this favorability was lost by 6 years. Freedom from structural failure was only 47% +/- 7% for the standard-profile valve at 10 years. Thus the probability of freedom from reoperation was only 46% +/- 7% after aortic valve replacement, 39% +/- 6% after mitral valve replacement, and 65% +/- 20% after double valve replacement at 10 years. Thromboembolism occurred in 69 patients, for a predicted freedom from this complication at 10 years of 79% +/- 3% after aortic, 73% +/- 7% after mitral, and 96% +/- 4% after double valve replacement. There were 31 cases of endocarditis. The 10-year predicted freedom from endocarditis, therefore, was 86% +/- 3% after aortic, 98% +/- 1% after mitral, and 97% +/- 1% after double valve replacement. A total of 221 operative and late deaths were recorded in this series. Prosthetic valve failure accounted for 27% of late deaths. The 10-year survival rates were estimated to be 56% +/- 5% (aortic valve replacement), 54% +/- 6% (mitral valve replacement), and 51% +/- 8% (double valve replacement). We concluded that the Ionescu-Shiley pericardial xenograft provides less than optimal clinical performance and its use has been discontinued.

Acceleration of tissue ingrowth on materials implanted in the heart.

A technique for accelerating the development of tissue layers on fabrics implanted in the bloodstream has been explored in dogs and monkeys. Endothelial cell seeding of the fabrics with cells derived from the endocardial surface of the atrium together with an autogenous plasma coating was shown to accelerate organization of fabric-covered devices implanted in the bloodstream of adult primates. At the same time, this technique appears simple and rapid enough to be practical in a clinical setting. The results suggest that this approach might be useful in accelerating the development of tissue layers on prosthetic valves implanted in the heart.

Submammary skin incision as a cosmetic approach to median sternotomy.

Median sternotomy is the incision of choice to allow access to the anterior mediastinum, heart, or both lungs. The vertical skin incision leaves an unsightly scar for many female patients. A bilateral submammary horizontal skin incision with dissection of a flap including the subcutaneous tissue and breasts allows exposure of the sternum so that a median sternotomy can be performed. Since November 1981, we have used this incision 40 times in female patients undergoing open heart surgery. The exposure of the mediastinum was excellent, and there were no difficulties in cannulating the ascending aorta for cardiopulmonary bypass. Complications associated with this incision are insignificant if close attention is paid to details.

Causes of death in aortocoronary bypass surgery: experience with 1,000 patients.

Of the first 1,000 consecutive patients in our unit to receive aortocoronary bypass grafts, 108 have died: 32 at operation, 16 in hospital, and 60 late. Of 343 patients who had a normal ventricle, only 1 (0.29%) died at operation, and 2 of the 8 late deaths were noncardiac in cause. Most operative deaths resulted from low cardiac output, and most later deaths were caused by congestive heart failure. A study of the relation of various clinical and operative factors with mortality found that patients with congestive heart failure who underwent valve replacement and bypass grafting had the worst prognosis (73% mortality) while those undergoing bypass grafting with Class III or IV ventricular function (as we define it) and congestive heart failure were next (49% mortality).

Ionescu-Shiley pericardial xenografts: follow-up of up to 6 years.

The results of valve replacement with the Ionescu-Shiley pericardial xenograft compare favorably with results obtained with other bioprostheses. From March, 1977, to July, 1983, 497 Ionescu-Shiley pericardial valves were implanted in 463 patients at the University of Ottawa Heart Institute. There were 292 patients who had aortic valve replacement (AVR), 140 with mitral valve replacement (MVR), 28 with double valve replacement, and 3 with triple valve replacement. The survivors were followed regularly. Actuarial analysis of late results indicates an expected survival of 71% at 6 years for patients who underwent AVR and 72% at 3 years for patients who had MVR. The only valve-related deaths were due to endocarditis, which occurred at a rate of 3.9% per patient-year for aortic valves and 0.6% per patient-year for mitral valves. Despite a low usage of formal anticoagulation, embolic complications occurred at a rate of 1.4% per patient-year for aortic valves and 4.0% per patient-year for mitral valves. Five valves were removed for intrinsic failure after 36 to 72 months of follow-up. New York Heart Association Functional Class improved an average of 1.28 classes per patient.

Persistent hypoxemia occurring as a complication of tricuspid valve endocarditis.

A 33-year-old woman had intravenous drug-associated tricuspid valve infective endocarditis. Despite resolution of septic pulmonary emboli, hypoxemia persisted. We report a case of right-to-left shunting across a previously insignificant patent foramen ovale documented by contrast transesophageal echocardiography. Although a rare complication of tricuspid endocarditis, clinicians should be aware of this potential correctable complication.

Direct drainage of the right pulmonary veins into the coronary sinus with intact interatrial septum: a case report.

Partial anomalous pulmonary venous connection to the coronary sinus is rare. This anomaly is even more rare in the absence of interatrial communication. Usually, the anomalous right pulmonary veins drain to the right atrium or venae cavae, while the anomalous left veins connect to the coronary sinus or left innominate vein. The present report is the first in the English literature to document a situs solitus case in which all three right pulmonary veins drained directly into the coronary sinus without an atrial septal defect. Closure of the coronary sinus orifice and unroofing of the coronary sinus into the left atrium is a safe and effective way of treating this anomaly.

Aortic dissection: a rare complication of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is an inherited connective tissue disorder, a group that includes Ehlers-Danlos syndrome, Marfan's syndrome and pseudoxanthoma elasticum. OI is a heterogeneous disease of collagen I biosynthesis characterized by variable clinical phenotypes, including skeletal and cardiovascular manifestations. A 65-year-old man with OI who had extensive prior successful cardiac valve surgeries is described. He survived for 18 years after his initial valve surgery, but died of multiorgan failure and sepsis after repair of a spontaneous type A aortic dissection. This is the fourth reported case of aortic dissection secondary to OI and illustrates the extensive cardiovascular pathology associated with OI. Aggressive management of arterial dissection risk factors, such as systemic arterial hypertension, is advocated for patients with OI.

Atypical hepatic vein leiomyoma extending into the right atrium: an unusual cause of the Budd-Chiari syndrome.

A 14-year-old male presented with a one week history of weakness, lightheadedness and vomiting. Bilateral pleural effusions were evident on chest radiography; electrocardiogram revealed decreased voltages. Echocardiogram, abdominal ultrasound and magnetic resonance imaging revealed a mass in an hepatic vein and the inferior vena cava extending up to and filling the right atrium. Under deep hypothermia and extracorporeal circulation the mass was removed en bloc. It originated from the hepatic vein. Pathology revealed a smooth muscle tumour intermediate between benign and malignant (atypical leiomyoma). This is the first reported pediatric primary leiomyoma of the hepatic vein. It caused the Budd-Chiari syndrome, a rare pediatric entity.

Balloon pulmonary valvuloplasty for congenital cyanotic heart defects.

Eight infants with congenital cyanotic heart defects, aged 7 days to 10 months, weighing 2.9 to 10.0 kg, underwent percutaneous balloon pulmonary valvuloplasty as a palliative procedure to improve pulmonary oligemia. The indication for valvuloplasty was cyanotic heart defect not amenable to total surgical correction at the age and size at presentation but at the same time requiring palliation of pulmonary oligemia. After balloon valvuloplasty, there was an increase in the pulmonary blood flow index (1.83 +/- 0.55 to 3.14 +/- 1.38 L/min/m2; p less than 0.05), pulmonary-to-systemic flow ratio (0.55 +/- 0.35 to 1.19 +/- 0.63; p less than 0.05), and pulmonary artery pressure (15.5 +/- 6.6 to 29.1 +/- 12.1 mm Hg; p less than 0.02). Arterial oxygen saturation, although increased from 69.6 +/- 11.5% to 81.4 +/- 12.3%, did not attain statistical significance (p greater than 0.05). Immediate surgical intervention was avoided in all eight patients. At follow-up, 4 to 12 months after balloon valvuloplasty, all infants were thriving with decreased hypoxemia and polycythemia. Follow-up catheterization data were available from six patients, 3 to 10 months after valvuloplasty, and in all of them the immediate postballoon valvuloplasty improvement persisted or further improvement noted. These data suggest that pulmonary valvuloplasty offers excellent palliation of pulmonary oligemia in cyanotic heart defects, thus avoiding the risks of immediate surgical palliation and paving the way for a better result of eventual total surgical correction.

First septal artery: direct or indirect grafting.

We retrospectively analyzed the revascularization of the septal artery achieved either directly through a coronary artery bypass graft (CABG) to the first septal artery (S1), or indirectly through endarterectomy and CABG of the anterior descending coronary artery (LAD). From July 1, 1976 to May 1, 1979, 21 84% (11 of 13). During the same period, 15 patients with a large S1 received endarterectomy and CABG of the LAD. Six of these 15 patients (40%) had an excellent flow into S1 as seen on the postoperative angiogram, whereas nine (60%) showed no improvement. The vein graft was patent and considered normal in 14 patients and the distal flow in the LAD was adequate in 10 patients (66%). We conclude that better revascularization of S1 is achieved by direct CABG. However, endarterectomy of the LAD allows revascularization of arteries that could not be grafted otherwise because of severe diffuse disease.