Possible role of juxtaglomerular apparatus in low cardiac output syndrome and multiple organ failure: modulation by high sodium load.

Sympathetic overdrive in acute low cardiac output syndrome, diverts blood from cutaneous and visceral circulation centripetally. Microcirculation in general, and renal circulation in particular, deteriorates during these circulatory adjustments leading to multi-organ failure (MOF). Decreased afferent glomerular arteriolar blood flow, increased renal sympathetic nerve discharge and a resultant decreased sodium chloride delivery around macula densa stimulates the Juxta-glomerular apparatus (JGA) and triggers renin-angiotensin-aldosterone mechanism. This, along with increased ADH production results in a state of vasoconstriction, increased after-load, and continued fluid retention, further compromising the visceral microcirculation. Initially the fluid retention under the effect of aldosterone and ADH is iso-osmotic, but later under inappropriate ADH action more water than salt is retained, as evidenced by the presence of hyponatraemia and 'water-logging' in the endstage of this condition.The author hypothesizes that: although physiological, the persistent stimulation of the JGA during the low cardiac output state plays an important role in perpetuating a negative cardiovascular vicious cycle and further aggravating it into MOF. Furthermore, by infusing hypertonic saline and hence increasing the sodium chloride delivery to the distal tubules and the macula densa, the JGA could be inhibited. This strategy should work like angiotensin-converting-enzyme-inhibitor drugs in chronic cardiac failure, except by acting at the root cause and inhibiting Renin production at its source. It should further help by stimulating atrial natriuretic peptide secretion.

Long-term results after aortic valve replacement in patients with congestive heart failure. Homografts vs prosthetic valves.

OBJECTIVES: The aim of this study was to assess the influence of valve substitute (homograft vs prosthetic valve) on the long-term survival and late valve-related complication rates following aortic valve replacement in patients with aortic valve disease and congestive heart failure. BACKGROUND: The effect of choice of valve substitute on outcome after aortic valve replacement in patients with pre-operative heart failure is unknown. The superior haemodynamic profile of homografts may be of particular benefit. METHODS: We retrospectively analysed pre-operative, operative and follow-up data on 518 adults in functional classes III and IV, who, over the 25 years 1969-1993, had their initial aortic valve replacement at Harefield hospital. Follow-up conducted during 1996 to April 1997 and totalling 4439 patient-years was 96.1% complete. Using multivariate analysis, independent risk factors for different complications and mortality were defined. RESULTS: Overall 5-, 10- and 20-year survival was 80+/-2%, 62+/-2% and 30+/-3%, respectively, with no significant difference between valve types. However, homografts (n=381) independently reduced the rate of serious complications and cardiac death, whereas mechanical valves were an independent adverse risk factor for late mortality. The rates of anticoagulant-related bleeding and thromboembolism were increased by mechanical valves, whereas primary tissue failure was the main complication of homografts. CONCLUSIONS: Long-term outcome of homograft aortic valve replacement in patients with congestive heart failure is acceptable, with a reduced rate of serious complications and cardiac death. Further improvements would be expected if the rate of primary tissue failure could be reduced.

Iatrogenic main pulmonary artery-left atrial fistula in a child.

A 14-month-old boy who underwent operation for ventricular septal defect patch closure and debanding of the pulmonary artery presented with arterial desaturation in the early postoperative period. Angiography confirmed the echocardiographic findings of hemodynamically significant main pulmonary artery-left atrial fistula. This communication was successfully closed surgically.

Primary aortic valve replacement with allografts over twenty-five years: valve-related and procedure-related determinants of outcome.

OBJECTIVES: Allografts offer many advantages over prosthetic valves, but allograft durability varies considerably. METHODS: From 1969 through 1993, 618 patients aged 15 to 84 years underwent their first aortic valve replacement with an aortic allograft. Concomitant surgery included aortic root tailoring (n = 58), replacement or tailoring of the ascending aorta (n = 56), and coronary artery bypass grafting (n = 87). Allograft implantation was done by means of a "freehand" subcoronary technique (n = 551) or total root replacement (n = 67). The allografts were antibiotic sterilized (n = 479), cryopreserved (n = 12), or viable (unprocessed, harvested from brain-dead multiorgan donors or heart transplant recipients, n = 127). Maximum follow-up was 27.1 years. RESULTS: Thirty-day mortality was 5.0%, and crude survival was 67% and 35% at 10 and 20 years. Ten- and 20-year rates of freedom from complications were as follows: endocarditis, 93% and 89%; primary tissue failure, 62% and 18%; and redo aortic valve replacement, 81% and 35%. Multivariable Cox analyses identified several valve- and procedure-related determinants: rising allograft donor age and antibiotic-sterilized allograft for mortality; donor more than 10 years older than patient for endocarditis; rising donor age minus patient age, rising implantation time (from harvest to aortic valve replacement), and donor age more than 65 years for tissue failure; and rising donor age minus patient age, young patient age, rising implantation time, and subcoronary implantation preceded by aortic root tailoring for redo aortic valve replacement. Estimated 10- and 20-year rates of freedom from tissue failure for a 70-year-old patient with a viable valve from a 30-year-old donor and no other risk factors were 91% and 64%; the figures were 71% and 20% if the donor age was 65 years. The rates of freedom from tissue failure for a 30-year-old patient with a 30-year-old donor were 82% and 39%; the figures were 49% and 3% with a 65-year-old donor. Beneficial influences of a viable valve were largely covered by short harvest time (no delay for allografts from brain dead organ donors or heart transplant recipients) and short implantation time. CONCLUSIONS: Primary allograft aortic valve replacement can give acceptable results for up to 25 years. The late results can be improved by the use of a viable allograft, by matching patient and donor age, and by more liberal use of free root replacement with re-implantation of the coronary arteries rather than tailoring the root to accommodate a subcoronary implantation.

Embolization of Gianturco coil into the pulmonary artery requiring emergency surgical intervention.

We report the case of a 20-month-old girl who underwent Gianturco coil embolization to a patent ductus arteriosus in May 1997. The coil migrated to the pulmonary artery. After unsuccessful attempts to retrieve it with snares and forceps, we engaged the coil with an end-hole balloon catheter and pulled it down to the right ventricle. There it became entangled in the tricuspid valvular apparatus and could not be moved farther. Due to concerns about sequelae, the patient was referred for surgery. Following a mid-sternotomy under cardiopulmonary bypass, we removed the coil and ligated the patent ductus arteriosus. The patient made an uneventful recovery. A brief review of the literature is presented.

Coronary artery fistula and atrial septal defect: a case report and brief review of the literature.

We present a case of a 25-year-old male with a large secondum atrial septal defect (ASD) associated with a coronary artery fistula (CAF) between the right coronary artery and the right atrium. The ASD was diagnosed preoperatively by transesophageal echocardio-graphy (TEE). The fistula was found at surgery. The ASD and fistula were closed successfully without any complication. The case highlights the common presenting features of the two conditions as well as the low sensitivity of pre-operative TEE in diagnosing CAF in the setting of an ASD.

Cardiopulmonary effects of 7.2% saline solution compared with gelatin infusion in the early postoperative period after coronary artery bypass grafting.

OBJECTIVE: We report a clinical study on the use of 7.2%, 2400 mOsm/L, hypertonic saline solution compared with gelatin in early postoperative period after coronary artery bypass surgery. METHODS: Two groups (n = 10 each) received 5 ml/kg of either saline solution or gelatin over 1 hour. Cardiac index, central venous pressure, pulmonary capillary wedge pressure, systemic and pulmonary vascular resistance indices, arterial oxygen tension, plasma osmolarity, electrolytes, and urinary output were recorded before starting the infusion and subsequently at 10, 30, 60, 90, 120, 240 and 600 minutes. Plasma creatinine, urea, electrolytes, urinary volume, and sodium excretion were measured at 12 and 24 hours. RESULTS: There were no significant demographic or operative difference between the groups. Patients receiving saline solution had a larger diuresis at 12 (p = 0.0008) and 24 hours (p = 0.002), with less positive balance at 12 hours (p = 0.0008). The group receiving saline solution had better cardiorespiratory recovery with shorter extubation time (p = 0.033), and earlier increase in cardiac index with a positive correlation between plasma sodium content and cardiac index. Maximum increase in cardiac index (+31%) occurred at 60 minutes (p = 0.025) associated with 8% increase in plasma sodium content (r = 0.51, p = 0.01), without a concomitant rise in pulmonary capillary wedge pressure. The group receiving gelatin had a linear increase in cardiac index with increasing pulmonary capillary wedge pressure, reaching +16% from baseline by 90 minutes. Compared with the gelatin-treated group, patients receiving saline solution had unchanged systemic vascular resistance index but a significantly lower pulmonary vascular resistance index with a negative correlation to plasma sodium content. There was no difference in levels of urea and creatinine. No side-effect attributable to the use of saline solution was observed.

Coronary steal through anomalous internal mammary artery graft. Treated by ligation without sternotomy.

A patient who had undergone adequate coronary revascularization with a left internal mammary artery graft to the left anterior descending coronary artery and with saphenous vein grafts to the right coronary artery and to the 1st and 2nd obtuse marginal branches presented with early-onset recurrent angina. A repeat angiogram showed an abnormally large branch arising from the very proximal segment of the left internal mammary artery and supplying the whole lateral chest wall via many intercostal tributaries. Relief of symptoms was achieved by ligation of this branch, and the patient remains symptom free more than 6 years after the procedure.

Gestational diabetes in a developing country, experience of screening at the Aga Khan University Medical Centre, Karachi.

In order to determine the prevalence of glucose intolerance in pregnancy, 1267 consecutive women attending the antenatal clinic of the Aga Khan University Medical Centre were subjected to a 75 g glucose challenge followed 2 hr later by plasma glucose determination irrespective of gestation on the first antenatal visit. The test was repeated at 28-32 weeks of gestation if the patients had an abnormal initial screen at less than 28 weeks gestation and a normal glucose tolerance test on diagnostic follow-up and for those who had a risk factor for gestational diabetes and a normal initial screen at less than 28 weeks gestation. The glucose challenge test was abnormal (2 hr plasma glucose greater than 140 mg%) in 8.6% of the screened population. Follow-up oral glucose tolerance test on these patients revealed a prevalence of 3.2% of gestational diabetes and 1.9% of impaired glucose tolerance test based on the modified O'Sullivan criteria. Improvement in cost effectiveness of screening programmes was adjudged possible by avoiding glucose tolerance tests in patients with 2 hr plasma glucose value of greater than 170 mg% after a 75 g oral glucose challenge for screening.