Myocardial revascularization without extracorporeal circulation in patients over 75 years of age: analysis of immediate results

Abstracts

OBJETIVO: Analisar os resultados imediatos da operação para revascularização do miocárdio sem circulação extracorpórea em pacientes acima de 75 anos. MÉTODOS: De janeiro 2001 a dezembro 2003, 193 pacientes com idade variando de 75 a 94 anos, correspondendo a 100% das operações coronarianas realizadas em pacientes acima de 75 anos, sendo 121 homens e 72 mulheres, foram submetidos a operação para revascularização do miocárdio sem circulação extracorpórea e analisados, retrospectivamente, os dados de internação dos pacientes. RESULTADOS: A hipertensão arterial esteve presente em 174 (90%), seguida de dislipidemia em 115 (59%), tabagismo em 89 (46%) e diabetes em 57 (29%), e 96 (49,7%) com antecedente de infarto do miocárdio. Destes, 53 (27,4%) tinham apresentado evento isquêmico agudo em um período < 30 dias da data da operação. Tinham lesões obstrutivas críticas em três ou mais vasos coronarianos 156 (80,95%) pacientes, enquanto 30 (15%) apresentavam obstrução do tronco da coronária esquerda e 30 (15%) apresentavam fração de ejeção < 30%. A pontuação obtida através do EUROSCORE variou de 3 a 18, com uma mortalidade esperada para o grupo de 7,54±2,69%. O número total de anastomoses distais foi de 639. Houve 7 (3,62%) óbitos, três por broncopneumonia, um por mediastinite, um por causas metabólicas, uma morte súbita após refixação de deiscência de esterno e um choque cardiogênico. Reoperação por sangramento, reintubação orotraqueal e ventilação mecânica prolongada foram fatores associados com aumento da mortalidade. CONCLUSÃO: A operação adotada para revascularização do miocárdio sem circulação extracorpórea foi associada à baixa mortalidade, baixo índice de complicações e curto período de hospitalização.

revascularização do miocárdio; circulação extracorpórea; idoso

ORIGINAL ARTICLE

Myocardial revascularization without extracorporeal circulation in patients over 75 years of age. Analysis of immediate results

Rodrigo Milani; Paulo Brofman; Alexandre Varela; Jose Augusto Souza; Maximiliano Guimarães; Rafael Pantarolli; Alexandre Barbosa; Laura Barbosa; Thaise Sandri; Luiz Gustavo Emed; Fernanda Ceccon; Francisco Maia

Curitiba, PR - Brazil

Serviço de Cirurgia Cardiovascular da Aliança Saúde - Pontifícia Universidade Católica do Paraná

^{Correspondence}

ABSTRACT

OBJECTIVE: To assess the immediate results of myocardial revascularization surgery without extracorporeal circulation in a group of patients over 75 years of age.

METHODS: From January 2001 to December 2003, 193 (121 men and 72 women) patients with ages ranging from 75 to 94 years, corresponding to 100% of the coronary surgeries performed in patients over the age of 75 years, underwent myocardial revascularization without extracorporeal circulation. Their hospitalization data were retrospectively analyzed.

RESULTS: Arterial hypertension was present in 174 (90%), dyslipidemia in 115 (59%), smoking in 89 (46%), and diabetes in 57 (29%). Ninety-six (49.7%) patients had had a previous myocardial infarction, 53 of whom (27.4%) had experienced an acute ischemic event in a period < 30 days after surgery. Critical obstructive lesions in 3 or more coronary vessels were present in 156 (80.95%) patients, while 30 (15%) patients had an important obstruction of the left main coronary artery, and 30 (15%) patients had an ejection fraction < 30%. The score obtained according to the EUROSCORE ranged from 3 to 18, with an expected mortality rate for the group of 7.54±2.69%. The total number of distal anastomoses was 639. Seven (3.62%) patients died, 3 due to bronchopneumonia, 1 due to mediastinitis, 1 due to metabolic causes, 1 due to cardiogenic shock, and another died suddenly after refixation of a sternal dehiscence. Reoperation due to bleeding, orotracheal reintubation, and prolonged mechanical ventilation were factors associated with an increase in mortality.

CONCLUSION: The surgery adopted for myocardial revascularization was associated with a low mortality rate, a low complication index, and a short length of stay at the hospital.

Keywords: elderly, myocardial revascularization surgery, extracorporeal circulation

The increase in the elderly population in Brazil in recent years has led to a greater number of patients over the age of 70 years requiring myocardial revascularization surgery. However, over the years, advanced age has been considered a risk factor for morbidity and mortality in coronary artery surgeries ^1,2. The recent advances in myocardial revascularization surgeries without extracorporeal circulation, the technique recommended by Buffolo et al ³ and Benetti ⁴ at the beginning of the 1980s, has aroused interest in this type of surgery, especially in high-risk patients ^5-7.

We retrospectively analyzed the immediate results of the myocardial revascularization surgery without extracorporeal circulation in patients over the age of 75 years.

Methods

Data of the present study were prospectively collected from the database used by the Society for Thoracic Surgery ⁸ and according to the risk index developed by the European Association for Cardiothoracic Surgery, EUROSCORE ^9,10. All patients over the age of 75 years, who underwent coronary surgery without extracorporeal circulation from January 2001 to December 2003 were analyzed.

The anesthetic technique used has been standardized and previously described ¹¹. After anesthetic induction and graft obtainment ¹¹, the patients were heparinized with a dose of 2.5 mg/kg. A 2-0 thread stitch fixed to a 3-cm-width cotton band was applied to the pericardial deflexion between the inferior vena cava and the right inferior pulmonary vein ¹² for complete exposure of the heart. The distal anastomoses were performed first, and the artery approached was occluded in its proximal portion to the anastomosis with a 4-0 thread stitch. The area of the anastomosis was exposed and fixed with a suction stabilizer (Octopuss System, Medtronic Corporation, Redmond, WA). At the end of the distal anastomoses, systolic blood pressure was maintained at 100 mm Hg, the aorta was partially clamped, and the proximal anastomoses were performed. When the anastomosing process was finished, 2 mg/kg of heparin were reverted with protamine sulfate and the surgery ended. Whenever possible, the patient was awakened from sedation in the operating room, and orotracheal extubation was performed. Then, the patient was sent to the intensive care unit, where he received continuous infusion of nitroglycerin and electrolyte replacement for 24 hours. Erythrocyte concentrate was administered whenever the hematocrit was below 30%.

Results

The study comprised 193 patients aged 75 to 94 years (mean, 78.5±3.14 years), who underwent myocardial revascularization without extracorporeal circulation, 121 (62.6%) being men and 72 (37.4%) women.

In regard to risk factors and associated diseases (tab. I), the patients were as follows: 29.5% were diabetic; 49.7% were smokers; 59.1% had elevated cholesterol levels; 90.1% were hypertensive; 4.1% had gastrointestinal disorders; 5.1% were chronic renal patients undergoing a dialysis program; 2.0% had had a previous vascular cerebral accident; 15.5% had chronic obstructive pulmonary disease; 15.5% had a peripheral vascular disorder; 1.5% had complete atrioventricular blockage; and 4.6% had chronic atrial fibrillation.

In regard to functional class, the patients were as follows: 15.5%, were in functional class I; 32.1%, in functional class II; 27.4%, in functional class III; and 24.8%, in functional class IV (fig. 1). Ninety-six (49.7%) patients had previous myocardial infarction and 27.4% had had a previous myocardial infarction within the 30 days preceding surgery. The ejection fraction was greater than 50% in 54.5% of the patients, between 30% and 50% in 30% of the patients, and lower than 30% in 15.5% (fig. 2).

Coronary cineangiography (tab. II) showed lesions in 1 vessel in 3% of the patients, in 2 vessels in 16% of the patients, and in 3 or more vessels in 81% of the patients. Twenty-two (17.4%) patients had a lesion in the left main coronary artery.

In regard to other preoperative antecedents, 32.1% of the patients had undergone previous angioplasty, 6.2% had undergone thrombolytic therapy due to acute myocardial infarction, 7.7% had undergone myocardial revascularization surgery, and 1% had definitive pacemaker. In the immediate preoperative period, 31% were using intravenous nitroglycerine for controlling angina, 5.1% were receiving a vasoactive drug due to significant hypotension, and 1% had used preoperative intra-aortic balloon. Nineteen (9.8%) patients underwent surgery on an emergency basis. The EUROSCORE score ranged from 3 to 18, with an expected mean mortality of 7.54±2.69%.

The total number of distal anastomoses was 639, with a mean of 3.26±1.18 per patient. The left internal thoracic artery and the radial artery were used in 132 (68.4%) and 38 (19.6%) patients, respectively. The mechanical ventilation duration ranged from zero to 216 hours, with a mean of 3 hours and 45 minutes. Eleven (5.6%) patients remained under mechanical ventilation for more than 24 hours; 49 (25.3%) were awakened and extubated in the operating room; 5 (2.5%) required orotracheal reintubation, none of whom belonged to the group extubated at the end of anesthesia. Twenty-six (13.4%) patients developed bronchopneumonia, 6 (54.5%) of whom belonged to the group with prolonged ventilation and 3 (60%) of whom belonged to the group that required orotracheal reintubation.

Three (1.5%) patients required reoperation due to bleeding. The mean drainage volume through the thorax and mediastinal drains was 420±155.4 mL (range, 50 to 1450 mL). Sixty-nine (35.7%) patients required no erythrocyte concentrate. Two (1%) patients had mediastinitis, and one had sternal dehiscence on the sixth postoperative day, and the patient was immediately referred for refixation. One (0.5%) patient experienced an ischemic cerebral vascular accident on the third postoperative day after an apparently normal recovery on the first days. Forty-three (22.2%) patients had acute atrial fibrillation in the postoperative period, 4 of whom required electrical cardioversion. Table III shows the major postoperative complications.

In this series, 7 (3.62%) patients died, one due to metabolic causes, one due to mediastinitis, one due to an unidentified cause on the second postoperative day of sternal refixation, one due to cardiogenic shock, and 3 due to bronchopneumonia. Death due to mediastinitis occurred in a patient who required reoperation due to bleeding. The other patient who required reoperation due to bleeding died because of bronchopneumonia on the eighth postoperative day. The third patient who required early reoperation for sternal refixation, died due to an unidentified cause. The other 2 patients who died required prolonged ventilation. The patient who died due to metabolic causes had been operated upon on an emergency basis. Table IV shows the causes of death.

The length of stay in the intensive care unit ranged from 22 to 216 hours; 49 (25.3%) patients stayed less than 24 hours; 102 (52.8%) stayed from 24 to 48 hours; 21 (11%) from 48 to 72 hours; and 21 (11%) stayed longer than 72 hours.

The length of stay at the hospital ranged from 4 to 26 days, and 143 (74%) patients were discharged on the sixth postoperative day.

Discussion

The increase in life expectancy of the population related to improvements in baseline health conditions, as well as the great advances in medicine worldwide in the past 15 years, allows cardiological management of patients over 70, and age has not been considered an obstacle for indicating any type of treatment. Recent studies have shown that life expectancy 10 years from now should be greater than 72 years ¹³.

The statistics have shown that the major cause of mortality in the elderly is cardiovascular disease, coronary artery disease accounting for more than 70% of the deaths in that age group ¹⁴, and congestive heart failure accounting for most hospitalizations ^15,16. Should advanced age be considered a factor of elevated risk for indicating coronary artery surgery?

The first consistent reports about the effectiveness of myocardial revascularization surgeries without extracorporeal circulation date back to the 1980s, when Buffolo et al ³ and Benetti ⁴, working in parallel with each other, reported the results in significant groups of patients. These authors showed that, with the aid of some surgical maneuvers and the use of drugs to reduce heart rate and oxygen consumption, the surgeries without extracorporeal circulation were safe, effective, and reproducible, and had low mortality, low morbidity, low cost, and, mainly, were highly effective in high-risk patients.

With those results and the new ones reported by both groups with a large number of patients over the entire decade, the interest in myocardial revascularization surgeries without extracorporeal circulation has gradually increased. In addition, the development of new instruments has gradually increased the applicability of the technique; for example, intraluminal shunt developed by Rivetti and Gandra ¹⁷ allows the performance of anastomoses without the need for occluding the vessel. Still, the great number of tissue stabilizers available on the market has also contributed to the increased interest in that type of surgery, making it increasingly reproducible. In our case series, we did not routinely use the intraluminal shunt, reserving it for the great arteries, especially the right coronary artery.

The Brazilian surgeon Gandra Lima ¹⁸ contributed by proposing maneuvers for presenting the vessels of the lateral and posterior wall of the heart, which provide less hemodynamic instability. By using a stitch applied between the inferior vena cava and the right inferior pulmonary vein, the author showed that any vessel in the heart could be approached; therefore, interest increased in myocardial revascularization surgeries without extracorporeal circulation. Studies carried out during the 1990s responded positively to the 2 questions posed by the critics to this type of surgery, ie, the quality of the anastomosis and incomplete revascularization when performed without extracorporeal circulation.

Confirming that myocardial revascularization surgery without extracorporeal circulation has lower morbidity, especially in high-risk patients, several studies have shown its applicability in patients over the age of 70 years with better results than those expected according to the predictive mortality indices ^19-23.

However, some aspects should be considered when the elderly undergo coronary artery surgery. In our case series, in agreement with observations of other authors^24-26, the incidence of complications was relatively low, but the tolerance to complications of a patient older than 75 years is lower than that observed in younger patients. Three factors were important in this series in regard to mortality: prolonged mechanical ventilation, orotracheal reintubation, and early reoperation.

Of the 193 patients assessed, 4 (2%) required reoperation, one due to sternal dehiscence and 3 due to bleeding. Three of them died. The incidence of bronchopneumonia was elevated among the patients who remained under prolonged ventilation (54%) or those who required reintubation (60%). The complication rate was low, considering that the incidence of complications, such as renal failure, myocardial infarction, cerebral vascular accidents, mediastinitis, and bleeding, common in this type of procedure, either were not observed or were observed in a small number of patients (less than 2%). However, these complications, when occurring, had a less favorable evolution than usual.

Myocardial revascularization surgery without extracorporeal circulation has gained a large number of enthusiasts, reaching 28% of the cases operated on in the United States. That figure is expected to increase to 50% by 2005. The applicability of the technique in 100% of the cases became possible with the aid of new stabilizers and the use of the technique reported by Lima et al ¹⁸ standardizing the exposure of the vessels of the lateral and posterior walls of the heart. As new results are reported in the literature, we believe that the number of surgeries without extracorporeal circulation will increase, reaching 100%.

In conclusion, patients older than 75 years present for surgery with less favorable clinical conditions than younger patients do, due to associated diseases. The myocardial revascularization surgery without extracorporeal circulation, once again, proved to be safe and effective, resulting in its greater indication in this specific population. The occurrence of postoperative complications has led to a significant increase in mortality; therefore, their presence should be detected early and treated aggressively.

References

Received for publication: 03/26/2003

Accepted for publication: 05/19/2004

English version by Stela Maris Costalonga

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Publication Dates

• Publication in this collection
  14 Feb 2005
• Date of issue
  Jan 2005

History

• Accepted
  19 May 2004
• Received
  26 Mar 2003